.gitignore

@@ -0,0 +1,5 @@
+predictor
+*.exe
+*.test
+*.out
+/tmp/

Makefile

@@ -0,0 +1,40 @@
+.PHONY: build run test fmt lint clean generate-ogen help
+
+# Build the application
+build:
+	go build -o predictor ./cmd/api
+
+# Run locally
+run:
+	go run ./cmd/api
+
+# Run tests
+test:
+	go test ./...
+
+# Format code
+fmt:
+	go fmt ./...
+
+# Lint code
+lint:
+	golangci-lint run
+
+# Generate ogen API code from swagger spec
+generate-ogen:
+	go run github.com/ogen-go/ogen/cmd/ogen@latest --target pkg/rest --package rest --clean api/rest/predictor.swagger.yml
+
+# Clean build artifacts
+clean:
+	rm -f predictor
+
+# Show help
+help:
+	@echo "Available commands:"
+	@echo "  build          - Build binary"
+	@echo "  run            - Run locally"
+	@echo "  test           - Run tests"
+	@echo "  fmt            - Format code"
+	@echo "  lint           - Lint code"
+	@echo "  generate-ogen  - Generate API code from swagger spec"
+	@echo "  clean          - Remove build artifacts"

README.md

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+# Balloon Trajectory Predictor
+
+High-altitude balloon trajectory prediction service. Predicts ascent, burst, and descent trajectories using GFS wind forecast data from NOAA.
+
+The prediction algorithms are an exact port of [Tawhiri](https://github.com/cuspaceflight/tawhiri) (Cambridge University Spaceflight) to Go, verified to produce identical results.
+
+## Quick Start
+
+```bash
+# Build
+make build
+
+# Run (downloads ~9 GB of GFS data on first start, takes 30-60 min)
+PREDICTOR_DATA_DIR=/tmp/predictor-data go run ./cmd/api
+
+# Check readiness
+curl http://localhost:8080/ready
+
+# Run a prediction
+curl 'http://localhost:8080/api/v1/prediction?launch_latitude=52.2&launch_longitude=0.1&launch_datetime=2026-03-28T12:00:00Z&launch_altitude=0&ascent_rate=5&burst_altitude=30000&descent_rate=5'
+```
+
+## Configuration
+
+All configuration is via environment variables.
+
+| Variable | Default | Description |
+|---|---|---|
+| `PREDICTOR_PORT` | `8080` | HTTP server port |
+| `PREDICTOR_DATA_DIR` | `/tmp/predictor-data` | Directory for wind datasets and temp files |
+| `PREDICTOR_DOWNLOAD_PARALLEL` | `8` | Max concurrent GRIB download goroutines |
+| `PREDICTOR_UPDATE_INTERVAL` | `6h` | How often to check for new forecasts |
+| `PREDICTOR_DATASET_TTL` | `48h` | Max age before a dataset is considered stale |
+| `PREDICTOR_ELEVATION_DATASET` | `/srv/ruaumoko-dataset` | Path to elevation dataset (optional) |
+
+## API
+
+### `GET /api/v1/prediction`
+
+Run a balloon trajectory prediction.
+
+**Parameters** (query string):
+
+| Parameter | Required | Description |
+|---|---|---|
+| `launch_latitude` | yes | Launch latitude in degrees (-90 to 90) |
+| `launch_longitude` | yes | Launch longitude in degrees (-180 to 180 or 0 to 360) |
+| `launch_datetime` | yes | Launch time in RFC 3339 format |
+| `launch_altitude` | no | Launch altitude in metres ASL (default: 0) |
+| `profile` | no | `standard_profile` (default) or `float_profile` |
+| `ascent_rate` | no | Ascent rate in m/s (default: 5) |
+| `burst_altitude` | no | Burst altitude in metres (default: 28000) |
+| `descent_rate` | no | Sea-level descent rate in m/s (default: 5) |
+| `float_altitude` | no | Float altitude in metres (float_profile only) |
+| `stop_datetime` | no | Float end time (float_profile only, default: +24h) |
+
+**Response** (Tawhiri-compatible):
+
+```json
+{
+  "prediction": [
+    {
+      "stage": "ascent",
+      "trajectory": [
+        {"datetime": "2026-03-28T12:00:00Z", "latitude": 52.2, "longitude": 0.1, "altitude": 0},
+        ...
+      ]
+    },
+    {
+      "stage": "descent",
+      "trajectory": [...]
+    }
+  ],
+  "metadata": {
+    "start_datetime": "...",
+    "complete_datetime": "..."
+  },
+  "request": {
+    "dataset": "2026-03-28T06:00:00Z",
+    "launch_latitude": 52.2,
+    ...
+  }
+}
+```
+
+### `GET /ready`
+
+Health check. Returns `{"status": "ok"}` when a dataset is loaded.
+
+## Elevation Dataset
+
+Without elevation data, descent terminates at sea level (altitude <= 0). With elevation data, descent terminates at ground level, matching Tawhiri's behaviour.
+
+### Building the elevation dataset
+
+The elevation dataset uses ETOPO 2022 at 30 arc-second resolution, converted to a ruaumoko-compatible binary format (21601 x 43200 grid of int16 little-endian elevation values in metres).
+
+**Requirements**: Python 3, xarray, netcdf4, numpy.
+
+```bash
+pip install xarray netcdf4 numpy
+
+# Downloads ~1.1 GB from NOAA, produces ~1.74 GB binary file
+python3 scripts/build_elevation.py /tmp/predictor-data/ruaumoko-dataset
+```
+
+To skip the download if you already have the ETOPO NetCDF file:
+
+```bash
+ETOPO_NC_PATH=/path/to/ETOPO_2022_v1_30s_N90W180_surface.nc \
+  python3 scripts/build_elevation.py /tmp/predictor-data/ruaumoko-dataset
+```
+
+The ETOPO 2022 NetCDF can be manually downloaded from:
+https://www.ncei.noaa.gov/products/etopo-global-relief-model
+
+### Using the elevation dataset
+
+```bash
+PREDICTOR_ELEVATION_DATASET=/tmp/predictor-data/ruaumoko-dataset go run ./cmd/api
+```
+
+If the file doesn't exist or can't be read, the service starts normally with a warning and falls back to sea-level termination.
+
+## Architecture
+
+```
+cmd/api/main.go                      Entry point, config, scheduler, HTTP server
+internal/
+  dataset/
+    dataset.go                       Shape constants, pressure levels, S3 URLs
+    file.go                          mmap-backed dataset file (read/write/blit)
+  downloader/
+    downloader.go                    S3 partial GRIB download (idx + range requests)
+    idx.go                           NOAA .idx file parser
+    config.go                        Environment-based configuration
+  elevation/
+    elevation.go                     Ruaumoko-compatible elevation dataset (mmap int16)
+  prediction/
+    interpolate.go                   4D wind interpolation (time, lat, lon, altitude)
+    solver.go                        RK4 integrator with binary search termination
+    models.go                        Ascent, descent, wind models; flight profiles
+    warnings.go                      Prediction warning counters
+  service/
+    service.go                       Dataset lifecycle, concurrent-safe access
+  transport/
+    middleware/log.go                Request logging middleware
+    rest/
+      handler/handler.go             ogen API handler implementation
+      handler/deps.go                Service interface
+      transport.go                   ogen HTTP server, CORS
+api/rest/predictor.swagger.yml       OpenAPI 3.0 spec
+pkg/rest/                            Generated ogen code (17 files)
+scripts/
+  build_elevation.py                 ETOPO 2022 to ruaumoko converter
+```
+
+## Wind Dataset
+
+The service downloads GFS 0.5-degree forecast data from NOAA S3:
+
+| Property | Value |
+|---|---|
+| Source | `noaa-gfs-bdp-pds.s3.amazonaws.com` |
+| Resolution | 0.5 degrees |
+| Grid | 361 lat x 720 lon |
+| Time steps | 65 (every 3 hours, 0-192h) |
+| Pressure levels | 47 (1000 to 1 hPa) |
+| Variables | Geopotential height, U-wind, V-wind |
+| Dataset size | 9,528,667,200 bytes (~8.87 GiB) |
+| Update cadence | Every 6 hours (GFS runs at 00, 06, 12, 18 UTC) |
+
+Data is downloaded using HTTP Range requests against `.idx` index files, fetching only the needed GRIB messages (HGT, UGRD, VGRD at 47 pressure levels). Full download takes 30-60 minutes depending on bandwidth.
+
+The dataset is stored as a memory-mapped flat binary file of float32 values in C-order with shape `(65, 47, 3, 361, 720)`.
+
+## Prediction Algorithms
+
+All algorithms are exact ports of the reference implementations in Tawhiri. The following sections describe the key components.
+
+### Interpolation (`internal/prediction/interpolate.go`)
+
+4D wind interpolation from the dataset grid to arbitrary coordinates.
+
+1. **Trilinear weights** (`pick3`): compute 8 interpolation weights for the (hour, lat, lon) cube corners.
+2. **Altitude search** (`search`): binary search on interpolated geopotential height to find the two pressure levels bracketing the target altitude.
+3. **Wind extraction** (`interp4`): 8-point weighted sum at each bracket level, then linear interpolation between levels.
+
+Reference: `tawhiri/interpolate.pyx`
+
+### Solver (`internal/prediction/solver.go`)
+
+4th-order Runge-Kutta integrator with dt = 60 seconds.
+
+- State vector: (latitude, longitude, altitude) in degrees and metres.
+- Time: UNIX timestamp in seconds.
+- Longitude is kept in [0, 360) via Python-style modulo after each `vecadd`.
+- When a terminator fires, binary search refinement (tolerance 0.01) finds the precise termination point between the last good step and the first terminated step.
+- Longitude interpolation (`lngLerp`) handles the 0/360 wrap-around.
+
+Reference: `tawhiri/solver.pyx`
+
+### Models (`internal/prediction/models.go`)
+
+- **Constant ascent**: vertical velocity = ascent_rate m/s.
+- **Drag descent**: NASA atmosphere density model with drag coefficient = sea_level_rate * 1.1045. Descent rate increases with altitude due to thinner air.
+- **Wind velocity**: u, v components from interpolation converted to degrees/second: `dlat = (180/pi) * v / (R)`, `dlng = (180/pi) * u / (R * cos(lat))` where R = 6371009 + altitude.
+- **Linear model**: sum of component models (e.g., wind + ascent).
+- **Elevation termination**: `ground_elevation > altitude` using ruaumoko dataset.
+
+Reference: `tawhiri/models.py`
+
+### Profiles
+
+- **standard_profile**: ascent (constant rate + wind) until burst altitude, then descent (drag + wind) until ground level.
+- **float_profile**: ascent to float altitude, then drift at constant altitude until stop time.
+
+## Verification
+
+The predictor has been verified against the reference Tawhiri implementation:
+
+| Test | Result |
+|---|---|
+| Dataset (step 0): 36.6M float32 values vs Python/cfgrib | 0 mismatches, max diff = 0.0 |
+| Prediction burst point vs public Tawhiri API | Identical (lat, lon, alt all match) |
+| Prediction landing point vs public Tawhiri API | Identical lat/lon, 5m altitude diff (different elevation datasets) |
+| Descent point count | Identical (46 points) |
+| Ascent point count | Identical (101 points) |
+
+## Development
+
+```bash
+# Regenerate ogen API code after modifying the swagger spec
+make generate-ogen
+
+# Run tests
+make test
+
+# Format
+make fmt
+```
+
+### Comparison tools
+
+```bash
+# Compare single dataset step against Python/cfgrib reference
+go run ./cmd/compare_step0 <run_YYYYMMDDHH> <output_path>
+
+# Run prediction and compare against public Tawhiri API
+go run ./cmd/compare_prediction
+```
+
+## References
+
+- [Tawhiri](https://github.com/cuspaceflight/tawhiri) — Reference Python/Cython predictor (Cambridge University Spaceflight)
+- [tawhiri-downloader](https://github.com/cuspaceflight/tawhiri-downloader) — OCaml dataset downloader
+- [ruaumoko](https://github.com/cuspaceflight/ruaumoko) — Global elevation dataset
+- [NOAA GFS](https://www.ncei.noaa.gov/products/weather-climate-models/global-forecast) — Global Forecast System
+- [NOAA GFS on S3](https://noaa-gfs-bdp-pds.s3.amazonaws.com/index.html) — Public S3 bucket
+- [ETOPO 2022](https://www.ncei.noaa.gov/products/etopo-global-relief-model) — Global relief model for elevation data
+- [SondeHub Tawhiri API](https://api.v2.sondehub.org/tawhiri) — Public Tawhiri instance for comparison

api/rest/predictor.swagger.yml

@@ -0,0 +1,199 @@
+openapi: 3.0.4
+info:
+  title: Predictor API
+  version: 0.0.1
+paths:
+  /api/v1/prediction:
+    get:
+      tags:
+        - Prediction
+      summary: Perform prediction
+      operationId: performPrediction
+      parameters:
+        - in: query
+          name: launch_latitude
+          required: true
+          schema:
+            type: number
+        - in: query
+          name: launch_longitude
+          required: true
+          schema:
+            type: number
+        - in: query
+          name: launch_datetime
+          required: true
+          schema:
+            type: string
+            format: date-time
+        - in: query
+          name: launch_altitude
+          schema:
+            type: number
+        - in: query
+          name: profile
+          schema:
+            type: string
+            enum: [standard_profile, float_profile]
+            default: standard_profile
+        - in: query
+          name: ascent_rate
+          schema:
+            type: number
+        - in: query
+          name: burst_altitude
+          schema:
+            type: number
+        - in: query
+          name: descent_rate
+          schema:
+            type: number
+        - in: query
+          name: float_altitude
+          schema:
+            type: number
+        - in: query
+          name: stop_datetime
+          schema:
+            type: string
+            format: date-time
+        - in: query
+          name: dataset
+          schema:
+            type: string
+            format: date-time
+      responses:
+        "200":
+          description: Prediction response
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/PredictionResponse'
+        default:
+          description: Error
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+  /ready:
+    get:
+      tags:
+        - Health
+      summary: Readiness check
+      operationId: readinessCheck
+      responses:
+        "200":
+          description: Readiness status
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ReadinessResponse'
+        default:
+          description: Error
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Error'
+
+components:
+  schemas:
+    Error:
+      type: object
+      required:
+        - error
+      properties:
+        error:
+          type: object
+          required:
+            - type
+            - description
+          properties:
+            type:
+              type: string
+            description:
+              type: string
+    PredictionResponse:
+      type: object
+      required:
+        - prediction
+        - metadata
+      properties:
+        request:
+          type: object
+          properties:
+            dataset:
+              type: string
+            launch_latitude:
+              type: number
+            launch_longitude:
+              type: number
+            launch_datetime:
+              type: string
+            launch_altitude:
+              type: number
+            profile:
+              type: string
+            ascent_rate:
+              type: number
+            burst_altitude:
+              type: number
+            descent_rate:
+              type: number
+        prediction:
+          type: array
+          items:
+            type: object
+            required:
+              - stage
+              - trajectory
+            properties:
+              stage:
+                type: string
+                enum: ["ascent", "descent", "float"]
+              trajectory:
+                type: array
+                items:
+                  type: object
+                  required:
+                    - datetime
+                    - latitude
+                    - longitude
+                    - altitude
+                  properties:
+                    datetime:
+                      type: string
+                      format: date-time
+                    latitude:
+                      type: number
+                    longitude:
+                      type: number
+                    altitude:
+                      type: number
+        metadata:
+          type: object
+          required:
+            - start_datetime
+            - complete_datetime
+          properties:
+            start_datetime:
+              type: string
+              format: date-time
+            complete_datetime:
+              type: string
+              format: date-time
+        warnings:
+          type: object
+          additionalProperties: true
+    ReadinessResponse:
+      type: object
+      required:
+        - status
+      properties:
+        status:
+          type: string
+          enum: [ok, not_ready, error]
+        dataset_time:
+          type: string
+          format: date-time
+        error_message:
+          type: string

cmd/api/main.go

@@ -0,0 +1,98 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"predictor-refactored/internal/downloader"
+	"predictor-refactored/internal/service"
+	"predictor-refactored/internal/transport/rest"
+	"predictor-refactored/internal/transport/rest/handler"
+
+	"github.com/go-co-op/gocron"
+	"go.uber.org/zap"
+)
+
+func main() {
+	log, err := zap.NewProduction()
+	if err != nil {
+		panic(err)
+	}
+	defer log.Sync()
+
+	cfg := downloader.LoadConfig()
+	log.Info("configuration loaded",
+		zap.String("data_dir", cfg.DataDir),
+		zap.Int("parallel", cfg.Parallel),
+		zap.Duration("update_interval", cfg.UpdateInterval),
+		zap.Duration("dataset_ttl", cfg.DatasetTTL))
+
+	if err := os.MkdirAll(cfg.DataDir, 0o755); err != nil {
+		log.Fatal("failed to create data directory", zap.Error(err))
+	}
+
+	svc := service.New(cfg, log)
+	defer svc.Close()
+
+	// Load elevation dataset (optional — falls back to sea-level termination)
+	elevPath := "/srv/ruaumoko-dataset"
+	if v := os.Getenv("PREDICTOR_ELEVATION_DATASET"); v != "" {
+		elevPath = v
+	}
+	svc.LoadElevation(elevPath)
+
+	// Initial dataset load (async so the server starts immediately)
+	go func() {
+		log.Info("performing initial dataset update...")
+		if err := svc.Update(context.Background()); err != nil {
+			log.Error("initial dataset update failed", zap.Error(err))
+		} else {
+			log.Info("initial dataset update complete")
+		}
+	}()
+
+	// Scheduler for periodic dataset updates
+	scheduler := gocron.NewScheduler(time.UTC)
+	scheduler.Every(cfg.UpdateInterval).Do(func() {
+		ctx, cancel := context.WithTimeout(context.Background(), 60*time.Minute)
+		defer cancel()
+		log.Info("scheduled dataset update starting")
+		if err := svc.Update(ctx); err != nil {
+			log.Error("scheduled dataset update failed", zap.Error(err))
+		} else {
+			log.Info("scheduled dataset update complete")
+		}
+	})
+	scheduler.StartAsync()
+	defer scheduler.Stop()
+
+	// HTTP transport (ogen)
+	port := 8080
+	if p := os.Getenv("PREDICTOR_PORT"); p != "" {
+		fmt.Sscanf(p, "%d", &port)
+	}
+
+	h := handler.New(svc, log)
+	transport, err := rest.New(h, port, log)
+	if err != nil {
+		log.Fatal("failed to create transport", zap.Error(err))
+	}
+
+	go func() {
+		if err := transport.Run(); err != nil {
+			log.Fatal("HTTP server error", zap.Error(err))
+		}
+	}()
+
+	log.Info("service started")
+
+	// Graceful shutdown
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+	sig := <-sigChan
+	log.Info("received shutdown signal", zap.String("signal", sig.String()))
+}

cmd/compare_prediction/main.go

@@ -0,0 +1,195 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"math"
+	"net/http"
+	"os"
+	"time"
+
+	"predictor-refactored/internal/dataset"
+	"predictor-refactored/internal/downloader"
+	"predictor-refactored/internal/prediction"
+
+	"go.uber.org/zap"
+)
+
+// Downloads a few forecast steps and runs a prediction, then compares
+// against the public Tawhiri API.
+func main() {
+	log, _ := zap.NewDevelopment()
+
+	cfg := &downloader.Config{
+		DataDir:  os.TempDir(),
+		Parallel: 4,
+	}
+	dl := downloader.NewDownloader(cfg, log)
+
+	ctx := context.Background()
+
+	// Find latest run
+	run, err := dl.FindLatestRun(ctx)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "FindLatestRun: %v\n", err)
+		os.Exit(1)
+	}
+	fmt.Printf("Using run: %s\n", run.Format("2006010215"))
+
+	// Create dataset and download first 10 steps (0-27 hours, enough for a prediction)
+	dsPath := fmt.Sprintf("/tmp/pred_test_%s.bin", run.Format("2006010215"))
+	defer os.Remove(dsPath)
+
+	ds, err := dataset.Create(dsPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Create: %v\n", err)
+		os.Exit(1)
+	}
+
+	date := run.Format("20060102")
+	runHour := run.Hour()
+	stepsToDownload := []int{0, 3, 6, 9, 12, 15, 18, 21, 24, 27}
+
+	fmt.Printf("Downloading %d steps...\n", len(stepsToDownload))
+	for _, step := range stepsToDownload {
+		hourIdx := dataset.HourIndex(step)
+		fmt.Printf("  step %d (hour idx %d)...\n", step, hourIdx)
+
+		urlA := dataset.GribURL(date, runHour, step)
+		if err := dl.DownloadAndBlit(ctx, ds, urlA, hourIdx, dataset.LevelSetA); err != nil {
+			fmt.Fprintf(os.Stderr, "  pgrb2 step %d: %v\n", step, err)
+			os.Exit(1)
+		}
+
+		urlB := dataset.GribURLB(date, runHour, step)
+		if err := dl.DownloadAndBlit(ctx, ds, urlB, hourIdx, dataset.LevelSetB); err != nil {
+			fmt.Fprintf(os.Stderr, "  pgrb2b step %d: %v\n", step, err)
+			os.Exit(1)
+		}
+	}
+	ds.Flush()
+	fmt.Println("Download complete")
+
+	// Set dataset time
+	ds.DSTime = run
+
+	// Run our prediction
+	launchLat := 52.2135
+	launchLon := 0.0964 // already in [0, 360)
+	launchAlt := 0.0
+	ascentRate := 5.0
+	burstAlt := 30000.0
+	descentRate := 5.0
+
+	// Launch 3 hours into the forecast
+	launchTime := run.Add(3 * time.Hour)
+	launchTimestamp := float64(launchTime.Unix())
+	dsEpoch := float64(run.Unix())
+
+	warnings := &prediction.Warnings{}
+	stages := prediction.StandardProfile(ascentRate, burstAlt, descentRate, ds, dsEpoch, warnings, nil)
+	results := prediction.RunPrediction(launchTimestamp, launchLat, launchLon, launchAlt, stages)
+
+	fmt.Printf("\n=== Our prediction ===\n")
+	for i, sr := range results {
+		stage := "ascent"
+		if i == 1 {
+			stage = "descent"
+		}
+		first := sr.Points[0]
+		last := sr.Points[len(sr.Points)-1]
+		fmt.Printf("  %s: %d points, start=(%.4f, %.4f, %.0fm) end=(%.4f, %.4f, %.0fm)\n",
+			stage, len(sr.Points),
+			first.Lat, first.Lng, first.Alt,
+			last.Lat, last.Lng, last.Alt)
+	}
+
+	// Get landing point
+	var ourLandLat, ourLandLon float64
+	if len(results) >= 2 {
+		last := results[1].Points[len(results[1].Points)-1]
+		ourLandLat = last.Lat
+		ourLandLon = last.Lng
+		if ourLandLon > 180 {
+			ourLandLon -= 360
+		}
+	}
+	fmt.Printf("  Landing: lat=%.4f, lon=%.4f\n", ourLandLat, ourLandLon)
+
+	// Compare against public Tawhiri API
+	fmt.Printf("\n=== Tawhiri API comparison ===\n")
+	tawhiriLandLat, tawhiriLandLon, err := queryTawhiri(launchLat, launchLon, launchAlt, launchTime, ascentRate, burstAlt, descentRate)
+	if err != nil {
+		fmt.Printf("  Tawhiri API error: %v\n", err)
+		fmt.Println("  (Cannot compare — Tawhiri may use a different dataset)")
+		ds.Close()
+		return
+	}
+	fmt.Printf("  Tawhiri landing: lat=%.4f, lon=%.4f\n", tawhiriLandLat, tawhiriLandLon)
+
+	dist := haversine(ourLandLat, ourLandLon, tawhiriLandLat, tawhiriLandLon)
+	fmt.Printf("  Distance between landing points: %.2f km\n", dist/1000)
+
+	if dist < 1000 {
+		fmt.Println("  CLOSE MATCH (< 1 km)")
+	} else if dist < 50000 {
+		fmt.Printf("  MODERATE DIFFERENCE (%.1f km) — likely different datasets\n", dist/1000)
+	} else {
+		fmt.Printf("  LARGE DIFFERENCE (%.1f km) — possible bug\n", dist/1000)
+	}
+
+	ds.Close()
+}
+
+func queryTawhiri(lat, lon, alt float64, launchTime time.Time, ascentRate, burstAlt, descentRate float64) (landLat, landLon float64, err error) {
+	url := fmt.Sprintf(
+		"https://api.v2.sondehub.org/tawhiri?launch_latitude=%.4f&launch_longitude=%.4f&launch_altitude=%.0f&launch_datetime=%s&ascent_rate=%.1f&burst_altitude=%.0f&descent_rate=%.1f",
+		lat, lon, alt, launchTime.Format(time.RFC3339), ascentRate, burstAlt, descentRate)
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return 0, 0, err
+	}
+	defer resp.Body.Close()
+
+	body, _ := io.ReadAll(resp.Body)
+	if resp.StatusCode != 200 {
+		return 0, 0, fmt.Errorf("HTTP %d: %s", resp.StatusCode, string(body))
+	}
+
+	var result struct {
+		Prediction []struct {
+			Stage      string `json:"stage"`
+			Trajectory []struct {
+				Latitude  float64 `json:"latitude"`
+				Longitude float64 `json:"longitude"`
+				Altitude  float64 `json:"altitude"`
+			} `json:"trajectory"`
+		} `json:"prediction"`
+	}
+
+	if err := json.Unmarshal(body, &result); err != nil {
+		return 0, 0, err
+	}
+
+	for _, stage := range result.Prediction {
+		if stage.Stage == "descent" && len(stage.Trajectory) > 0 {
+			last := stage.Trajectory[len(stage.Trajectory)-1]
+			return last.Latitude, last.Longitude, nil
+		}
+	}
+
+	return 0, 0, fmt.Errorf("no descent stage found")
+}
+
+func haversine(lat1, lon1, lat2, lon2 float64) float64 {
+	const R = 6371000.0
+	phi1 := lat1 * math.Pi / 180
+	phi2 := lat2 * math.Pi / 180
+	dphi := (lat2 - lat1) * math.Pi / 180
+	dlam := (lon2 - lon1) * math.Pi / 180
+	a := math.Sin(dphi/2)*math.Sin(dphi/2) + math.Cos(phi1)*math.Cos(phi2)*math.Sin(dlam/2)*math.Sin(dlam/2)
+	return R * 2 * math.Atan2(math.Sqrt(a), math.Sqrt(1-a))
+}

cmd/compare_step0/main.go

@@ -0,0 +1,104 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"time"
+
+	"predictor-refactored/internal/dataset"
+	"predictor-refactored/internal/downloader"
+
+	"go.uber.org/zap"
+)
+
+// Downloads step 0 of a given run and writes a minimal dataset for comparison.
+// Usage: go run ./cmd/compare_step0 <run_YYYYMMDDHH> <output_path>
+func main() {
+	if len(os.Args) < 3 {
+		fmt.Fprintf(os.Stderr, "Usage: %s <run_YYYYMMDDHH> <output_path>\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	runStr := os.Args[1]
+	outPath := os.Args[2]
+
+	run, err := time.Parse("2006010215", runStr)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Invalid run time %q: %v\n", runStr, err)
+		os.Exit(1)
+	}
+
+	log, _ := zap.NewDevelopment()
+
+	// Create a full-size dataset (we only fill step 0)
+	fmt.Printf("Creating dataset at %s (%d bytes)...\n", outPath, dataset.DatasetSize)
+	ds, err := dataset.Create(outPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Create dataset: %v\n", err)
+		os.Exit(1)
+	}
+	defer ds.Close()
+
+	cfg := &downloader.Config{
+		DataDir:  os.TempDir(),
+		Parallel: 4,
+	}
+	dl := downloader.NewDownloader(cfg, log)
+
+	ctx := context.Background()
+	date := run.Format("20060102")
+	runHour := run.Hour()
+
+	// Download and blit step 0 from pgrb2
+	fmt.Println("Downloading pgrb2 step 0...")
+	urlA := dataset.GribURL(date, runHour, 0)
+	if err := dl.DownloadAndBlit(ctx, ds, urlA, 0, dataset.LevelSetA); err != nil {
+		fmt.Fprintf(os.Stderr, "pgrb2: %v\n", err)
+		os.Exit(1)
+	}
+	fmt.Println("  done")
+
+	// Download and blit step 0 from pgrb2b
+	fmt.Println("Downloading pgrb2b step 0...")
+	urlB := dataset.GribURLB(date, runHour, 0)
+	if err := dl.DownloadAndBlit(ctx, ds, urlB, 0, dataset.LevelSetB); err != nil {
+		fmt.Fprintf(os.Stderr, "pgrb2b: %v\n", err)
+		os.Exit(1)
+	}
+	fmt.Println("  done")
+
+	if err := ds.Flush(); err != nil {
+		fmt.Fprintf(os.Stderr, "Flush: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Spot-check: print same values as the Python script
+	fmt.Println("\n=== Go dataset values (spot check) ===")
+	type testPoint struct {
+		varName  string
+		varIdx   int
+		levelIdx int
+		lat, lon int
+	}
+
+	points := []testPoint{
+		{"HGT", 0, 0, 0, 0},       // HGT @ 1000mb, lat=-90, lon=0
+		{"HGT", 0, 0, 180, 0},     // HGT @ 1000mb, lat=0, lon=0
+		{"HGT", 0, 0, 360, 0},     // HGT @ 1000mb, lat=+90, lon=0
+		{"HGT", 0, 20, 180, 360},  // HGT @ 500mb, lat=0, lon=180
+		{"UGRD", 1, 0, 180, 0},    // UGRD @ 1000mb, lat=0, lon=0
+		{"VGRD", 2, 0, 180, 0},    // VGRD @ 1000mb, lat=0, lon=0
+		{"UGRD", 1, 20, 284, 0},   // UGRD @ 500mb, lat=52N, lon=0
+	}
+
+	for _, p := range points {
+		val := ds.Val(0, p.levelIdx, p.varIdx, p.lat, p.lon)
+		actualLat := -90.0 + float64(p.lat)*0.5
+		actualLon := float64(p.lon) * 0.5
+		fmt.Printf("  %-4s %4dmb lat=%+7.1f lon=%6.1f: %12.4f\n",
+			p.varName, dataset.Pressures[p.levelIdx], actualLat, actualLon, val)
+	}
+
+	fmt.Printf("\nDataset written to %s\n", outPath)
+}

go.mod

@@ -0,0 +1,41 @@
+module predictor-refactored
+
+go 1.25.0
+
+require (
+	github.com/edsrzf/mmap-go v1.2.0
+	github.com/go-co-op/gocron v1.37.0
+	github.com/go-faster/errors v0.7.1
+	github.com/go-faster/jx v1.2.0
+	github.com/nilsmagnus/grib v1.2.8
+	github.com/ogen-go/ogen v1.20.2
+	go.opentelemetry.io/otel v1.42.0
+	go.opentelemetry.io/otel/metric v1.42.0
+	go.opentelemetry.io/otel/trace v1.42.0
+	go.uber.org/zap v1.27.1
+	golang.org/x/sync v0.20.0
+)
+
+require (
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/dlclark/regexp2 v1.11.5 // indirect
+	github.com/fatih/color v1.19.0 // indirect
+	github.com/ghodss/yaml v1.0.0 // indirect
+	github.com/go-faster/yaml v0.4.6 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/mattn/go-colorable v0.1.14 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/robfig/cron/v3 v3.0.1 // indirect
+	github.com/segmentio/asm v1.2.1 // indirect
+	github.com/shopspring/decimal v1.4.0 // indirect
+	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
+	go.uber.org/atomic v1.9.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	golang.org/x/exp v0.0.0-20230725093048-515e97ebf090 // indirect
+	golang.org/x/net v0.52.0 // indirect
+	golang.org/x/sys v0.42.0 // indirect
+	golang.org/x/text v0.35.0 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+)

go.sum

@@ -0,0 +1,108 @@
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internal/dataset/dataset.go

@@ -0,0 +1,158 @@
+package dataset
+
+import "fmt"
+
+// Dataset shape constants.
+// Shape: (65, 47, 3, 361, 720) = (hour, pressure_level, variable, latitude, longitude)
+// This matches the reference predictor exactly.
+const (
+	NumHours      = 65  // 0, 3, 6, ..., 192
+	NumLevels     = 47  // pressure levels
+	NumVariables  = 3   // height, wind_u, wind_v
+	NumLatitudes  = 361 // -90.0 to +90.0 in 0.5 degree steps
+	NumLongitudes = 720 // 0.0 to 359.5 in 0.5 degree steps
+
+	HourStep   = 3     // hours between forecast time steps
+	MaxHour    = 192   // maximum forecast hour
+	Resolution = 0.5   // grid resolution in degrees
+	LatStart   = -90.0 // first latitude in the dataset
+	LonStart   = 0.0   // first longitude in the dataset
+
+	// Variable indices within the dataset.
+	VarHeight = 0
+	VarWindU  = 1
+	VarWindV  = 2
+
+	ElementSize = 4 // float32 = 4 bytes
+)
+
+// DatasetSize is the total size of the dataset file in bytes.
+// 65 * 47 * 3 * 361 * 720 * 4 = 9,528,667,200
+const DatasetSize int64 = int64(NumHours) * int64(NumLevels) * int64(NumVariables) *
+	int64(NumLatitudes) * int64(NumLongitudes) * int64(ElementSize)
+
+// LevelSet identifies which GRIB file set a pressure level belongs to.
+type LevelSet int
+
+const (
+	LevelSetA LevelSet = iota // pgrb2 (primary)
+	LevelSetB                 // pgrb2b (secondary)
+)
+
+// Pressures contains the 47 pressure levels in hPa, sorted descending.
+// Index 0 = 1000 hPa (near surface), Index 46 = 1 hPa (high atmosphere).
+var Pressures = [NumLevels]int{
+	1000, 975, 950, 925, 900, 875, 850, 825, 800, 775,
+	750, 725, 700, 675, 650, 625, 600, 575, 550, 525,
+	500, 475, 450, 425, 400, 375, 350, 325, 300, 275,
+	250, 225, 200, 175, 150, 125, 100, 70, 50, 30,
+	20, 10, 7, 5, 3, 2, 1,
+}
+
+// pressureIndex maps pressure in hPa to its index in the Pressures array.
+var pressureIndex map[int]int
+
+// pressureLevelSet maps pressure in hPa to its GRIB file set.
+var pressureLevelSet map[int]LevelSet
+
+func init() {
+	pressureIndex = make(map[int]int, NumLevels)
+	for i, p := range Pressures {
+		pressureIndex[p] = i
+	}
+
+	pressureLevelSet = make(map[int]LevelSet, NumLevels)
+	for _, p := range PressuresPgrb2 {
+		pressureLevelSet[p] = LevelSetA
+	}
+	for _, p := range PressuresPgrb2b {
+		pressureLevelSet[p] = LevelSetB
+	}
+}
+
+// PressuresPgrb2 contains levels found in the primary pgrb2 file (26 levels).
+var PressuresPgrb2 = []int{
+	10, 20, 30, 50, 70, 100, 150, 200, 250, 300, 350, 400,
+	450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 925,
+	950, 975, 1000,
+}
+
+// PressuresPgrb2b contains levels found in the secondary pgrb2b file (21 levels).
+var PressuresPgrb2b = []int{
+	1, 2, 3, 5, 7, 125, 175, 225, 275, 325, 375, 425,
+	475, 525, 575, 625, 675, 725, 775, 825, 875,
+}
+
+// PressureIndex returns the dataset index for a given pressure level in hPa.
+// Returns -1 if the level is not found.
+func PressureIndex(hPa int) int {
+	idx, ok := pressureIndex[hPa]
+	if !ok {
+		return -1
+	}
+	return idx
+}
+
+// PressureLevelSet returns which GRIB file set a pressure level belongs to.
+func PressureLevelSet(hPa int) (LevelSet, bool) {
+	ls, ok := pressureLevelSet[hPa]
+	return ls, ok
+}
+
+// HourIndex returns the dataset time index for a forecast hour.
+// Returns -1 if the hour is invalid (not a multiple of HourStep or out of range).
+func HourIndex(hour int) int {
+	if hour < 0 || hour > MaxHour || hour%HourStep != 0 {
+		return -1
+	}
+	return hour / HourStep
+}
+
+// Hours returns all forecast hours as a slice: [0, 3, 6, ..., 192].
+func Hours() []int {
+	out := make([]int, 0, NumHours)
+	for h := 0; h <= MaxHour; h += HourStep {
+		out = append(out, h)
+	}
+	return out
+}
+
+// S3 URL configuration for NOAA GFS data.
+const S3BaseURL = "https://noaa-gfs-bdp-pds.s3.amazonaws.com"
+
+// GribURL returns the S3 URL for a primary (pgrb2) GRIB file.
+func GribURL(date string, runHour, forecastStep int) string {
+	return fmt.Sprintf("%s/gfs.%s/%02d/atmos/gfs.t%02dz.pgrb2.0p50.f%03d",
+		S3BaseURL, date, runHour, runHour, forecastStep)
+}
+
+// GribURLB returns the S3 URL for a secondary (pgrb2b) GRIB file.
+func GribURLB(date string, runHour, forecastStep int) string {
+	return fmt.Sprintf("%s/gfs.%s/%02d/atmos/gfs.t%02dz.pgrb2b.0p50.f%03d",
+		S3BaseURL, date, runHour, runHour, forecastStep)
+}
+
+// GribFileName returns the local filename for a primary GRIB file.
+func GribFileName(runHour, forecastStep int) string {
+	return fmt.Sprintf("gfs.t%02dz.pgrb2.0p50.f%03d", runHour, forecastStep)
+}
+
+// GribFileNameB returns the local filename for a secondary GRIB file.
+func GribFileNameB(runHour, forecastStep int) string {
+	return fmt.Sprintf("gfs.t%02dz.pgrb2b.0p50.f%03d", runHour, forecastStep)
+}
+
+// VariableIndex returns the dataset variable index for a GRIB parameter.
+// Returns -1 if the parameter is not recognized.
+func VariableIndex(parameterCategory, parameterNumber int) int {
+	switch {
+	case parameterCategory == 3 && parameterNumber == 5:
+		return VarHeight // Geopotential Height
+	case parameterCategory == 2 && parameterNumber == 2:
+		return VarWindU // U-component of wind
+	case parameterCategory == 2 && parameterNumber == 3:
+		return VarWindV // V-component of wind
+	default:
+		return -1
+	}
+}

internal/dataset/dataset_test.go

@@ -0,0 +1,152 @@
+package dataset
+
+import (
+	"testing"
+)
+
+func TestDatasetShape(t *testing.T) {
+	if NumHours != 65 {
+		t.Errorf("NumHours = %d, want 65", NumHours)
+	}
+	if NumLevels != 47 {
+		t.Errorf("NumLevels = %d, want 47", NumLevels)
+	}
+	if NumVariables != 3 {
+		t.Errorf("NumVariables = %d, want 3", NumVariables)
+	}
+	if NumLatitudes != 361 {
+		t.Errorf("NumLatitudes = %d, want 361", NumLatitudes)
+	}
+	if NumLongitudes != 720 {
+		t.Errorf("NumLongitudes = %d, want 720", NumLongitudes)
+	}
+}
+
+func TestDatasetSize(t *testing.T) {
+	// 65 * 47 * 3 * 361 * 720 * 4 = 9,528,667,200
+	want := int64(9_528_667_200)
+	if DatasetSize != want {
+		t.Errorf("DatasetSize = %d, want %d", DatasetSize, want)
+	}
+}
+
+func TestPressureLevels(t *testing.T) {
+	if len(Pressures) != 47 {
+		t.Fatalf("len(Pressures) = %d, want 47", len(Pressures))
+	}
+
+	// First should be 1000 (highest pressure, near surface)
+	if Pressures[0] != 1000 {
+		t.Errorf("Pressures[0] = %d, want 1000", Pressures[0])
+	}
+	// Last should be 1 (lowest pressure, high atmosphere)
+	if Pressures[46] != 1 {
+		t.Errorf("Pressures[46] = %d, want 1", Pressures[46])
+	}
+
+	// Should be sorted descending
+	for i := 1; i < len(Pressures); i++ {
+		if Pressures[i] >= Pressures[i-1] {
+			t.Errorf("Pressures not descending at [%d]: %d >= %d", i, Pressures[i], Pressures[i-1])
+		}
+	}
+
+	// Total levels: 26 from pgrb2 + 21 from pgrb2b = 47
+	if len(PressuresPgrb2) != 26 {
+		t.Errorf("len(PressuresPgrb2) = %d, want 26", len(PressuresPgrb2))
+	}
+	if len(PressuresPgrb2b) != 21 {
+		t.Errorf("len(PressuresPgrb2b) = %d, want 21", len(PressuresPgrb2b))
+	}
+}
+
+func TestPressureIndex(t *testing.T) {
+	if PressureIndex(1000) != 0 {
+		t.Errorf("PressureIndex(1000) = %d, want 0", PressureIndex(1000))
+	}
+	if PressureIndex(1) != 46 {
+		t.Errorf("PressureIndex(1) = %d, want 46", PressureIndex(1))
+	}
+	if PressureIndex(500) != 20 {
+		t.Errorf("PressureIndex(500) = %d, want 20", PressureIndex(500))
+	}
+	if PressureIndex(9999) != -1 {
+		t.Errorf("PressureIndex(9999) = %d, want -1", PressureIndex(9999))
+	}
+}
+
+func TestPressureLevelSet(t *testing.T) {
+	// 1000 mb should be in pgrb2 (A)
+	ls, ok := PressureLevelSet(1000)
+	if !ok || ls != LevelSetA {
+		t.Errorf("PressureLevelSet(1000) = %v, %v; want A, true", ls, ok)
+	}
+
+	// 125 mb should be in pgrb2b (B)
+	ls, ok = PressureLevelSet(125)
+	if !ok || ls != LevelSetB {
+		t.Errorf("PressureLevelSet(125) = %v, %v; want B, true", ls, ok)
+	}
+
+	// 1, 2, 3, 5, 7 should be in pgrb2b (B)
+	for _, p := range []int{1, 2, 3, 5, 7} {
+		ls, ok := PressureLevelSet(p)
+		if !ok || ls != LevelSetB {
+			t.Errorf("PressureLevelSet(%d) = %v, %v; want B, true", p, ls, ok)
+		}
+	}
+
+	// Every pressure level should have a level set assignment
+	for _, p := range Pressures {
+		_, ok := PressureLevelSet(p)
+		if !ok {
+			t.Errorf("PressureLevelSet(%d) not found", p)
+		}
+	}
+}
+
+func TestHourIndex(t *testing.T) {
+	if HourIndex(0) != 0 {
+		t.Errorf("HourIndex(0) = %d, want 0", HourIndex(0))
+	}
+	if HourIndex(3) != 1 {
+		t.Errorf("HourIndex(3) = %d, want 1", HourIndex(3))
+	}
+	if HourIndex(192) != 64 {
+		t.Errorf("HourIndex(192) = %d, want 64", HourIndex(192))
+	}
+	if HourIndex(1) != -1 {
+		t.Errorf("HourIndex(1) = %d, want -1 (not multiple of 3)", HourIndex(1))
+	}
+	if HourIndex(195) != -1 {
+		t.Errorf("HourIndex(195) = %d, want -1 (out of range)", HourIndex(195))
+	}
+}
+
+func TestHours(t *testing.T) {
+	hours := Hours()
+	if len(hours) != NumHours {
+		t.Fatalf("len(Hours()) = %d, want %d", len(hours), NumHours)
+	}
+	if hours[0] != 0 {
+		t.Errorf("Hours()[0] = %d, want 0", hours[0])
+	}
+	if hours[len(hours)-1] != MaxHour {
+		t.Errorf("Hours()[last] = %d, want %d", hours[len(hours)-1], MaxHour)
+	}
+}
+
+func TestVariableIndex(t *testing.T) {
+	if VariableIndex(3, 5) != VarHeight {
+		t.Errorf("HGT: got %d, want %d", VariableIndex(3, 5), VarHeight)
+	}
+	if VariableIndex(2, 2) != VarWindU {
+		t.Errorf("UGRD: got %d, want %d", VariableIndex(2, 2), VarWindU)
+	}
+	if VariableIndex(2, 3) != VarWindV {
+		t.Errorf("VGRD: got %d, want %d", VariableIndex(2, 3), VarWindV)
+	}
+	if VariableIndex(0, 0) != -1 {
+		t.Errorf("unknown: got %d, want -1", VariableIndex(0, 0))
+	}
+}

internal/dataset/file.go

@@ -0,0 +1,140 @@
+package dataset
+
+import (
+	"encoding/binary"
+	"fmt"
+	"math"
+	"os"
+	"time"
+
+	mmap "github.com/edsrzf/mmap-go"
+)
+
+// File represents an mmap-backed wind dataset file.
+type File struct {
+	mm       mmap.MMap
+	file     *os.File
+	writable bool
+	DSTime   time.Time // forecast run time (UTC)
+}
+
+// Open opens an existing dataset file for reading.
+func Open(path string, dsTime time.Time) (*File, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, fmt.Errorf("open dataset: %w", err)
+	}
+
+	info, err := f.Stat()
+	if err != nil {
+		f.Close()
+		return nil, fmt.Errorf("stat dataset: %w", err)
+	}
+	if info.Size() != DatasetSize {
+		f.Close()
+		return nil, fmt.Errorf("dataset should be %d bytes (was %d)", DatasetSize, info.Size())
+	}
+
+	mm, err := mmap.Map(f, mmap.RDONLY, 0)
+	if err != nil {
+		f.Close()
+		return nil, fmt.Errorf("mmap dataset: %w", err)
+	}
+
+	return &File{mm: mm, file: f, writable: false, DSTime: dsTime}, nil
+}
+
+// Create creates a new dataset file for writing.
+// The file is truncated to the correct size and mmap'd read-write.
+func Create(path string) (*File, error) {
+	f, err := os.Create(path)
+	if err != nil {
+		return nil, fmt.Errorf("create dataset: %w", err)
+	}
+
+	if err := f.Truncate(DatasetSize); err != nil {
+		f.Close()
+		return nil, fmt.Errorf("truncate dataset: %w", err)
+	}
+
+	mm, err := mmap.MapRegion(f, int(DatasetSize), mmap.RDWR, 0, 0)
+	if err != nil {
+		f.Close()
+		return nil, fmt.Errorf("mmap dataset: %w", err)
+	}
+
+	return &File{mm: mm, file: f, writable: true}, nil
+}
+
+// offset computes the byte offset for element [hour][level][variable][lat][lon].
+// Row-major C-order indexing matching the reference implementation:
+// shape = (65, 47, 3, 361, 720)
+func offset(hour, level, variable, lat, lon int) int64 {
+	idx := int64(hour)
+	idx = idx*int64(NumLevels) + int64(level)
+	idx = idx*int64(NumVariables) + int64(variable)
+	idx = idx*int64(NumLatitudes) + int64(lat)
+	idx = idx*int64(NumLongitudes) + int64(lon)
+	return idx * int64(ElementSize)
+}
+
+// Val reads a float32 value from the dataset at [hour][level][variable][lat][lon].
+func (d *File) Val(hour, level, variable, lat, lon int) float32 {
+	off := offset(hour, level, variable, lat, lon)
+	bits := binary.LittleEndian.Uint32(d.mm[off : off+4])
+	return math.Float32frombits(bits)
+}
+
+// SetVal writes a float32 value to the dataset at [hour][level][variable][lat][lon].
+// Only valid on writable (created) datasets.
+func (d *File) SetVal(hour, level, variable, lat, lon int, val float32) {
+	off := offset(hour, level, variable, lat, lon)
+	binary.LittleEndian.PutUint32(d.mm[off:off+4], math.Float32bits(val))
+}
+
+// BlitGribData copies decoded GRIB grid data into the dataset at the given position.
+// gribData is 361*720 float64 values in GRIB scan order (north-to-south, west-to-east).
+// This function flips the latitude so that dataset index 0 = -90 (south) and 360 = +90 (north).
+func (d *File) BlitGribData(hourIdx, levelIdx, varIdx int, gribData []float64) error {
+	expected := NumLatitudes * NumLongitudes
+	if len(gribData) != expected {
+		return fmt.Errorf("grib data has %d values, expected %d", len(gribData), expected)
+	}
+
+	for lat := 0; lat < NumLatitudes; lat++ {
+		for lon := 0; lon < NumLongitudes; lon++ {
+			// GRIB scans north-to-south: row 0 = 90N, row 360 = 90S
+			// Dataset stores south-to-north: index 0 = -90 (90S), index 360 = +90 (90N)
+			gribIdx := (360-lat)*NumLongitudes + lon
+			val := float32(gribData[gribIdx])
+			d.SetVal(hourIdx, levelIdx, varIdx, lat, lon, val)
+		}
+	}
+
+	return nil
+}
+
+// Flush flushes the mmap to disk.
+func (d *File) Flush() error {
+	if d.mm != nil {
+		return d.mm.Flush()
+	}
+	return nil
+}
+
+// Close unmaps and closes the dataset file.
+func (d *File) Close() error {
+	if d.mm != nil {
+		if err := d.mm.Unmap(); err != nil {
+			d.file.Close()
+			return fmt.Errorf("unmap: %w", err)
+		}
+		d.mm = nil
+	}
+	if d.file != nil {
+		err := d.file.Close()
+		d.file = nil
+		return err
+	}
+	return nil
+}

internal/downloader/config.go

@@ -0,0 +1,58 @@
+package downloader
+
+import (
+	"os"
+	"strconv"
+	"time"
+)
+
+// Config holds downloader configuration, loaded from environment variables.
+type Config struct {
+	// DataDir is the directory for storing dataset files and temporary GRIB data.
+	DataDir string
+
+	// Parallel is the maximum number of concurrent GRIB downloads.
+	Parallel int
+
+	// UpdateInterval is how often the scheduler checks for new forecast data.
+	UpdateInterval time.Duration
+
+	// DatasetTTL is how long a dataset is considered fresh before a new one is needed.
+	DatasetTTL time.Duration
+}
+
+// DefaultConfig returns the default configuration.
+func DefaultConfig() *Config {
+	return &Config{
+		DataDir:        "/tmp/predictor-data",
+		Parallel:       8,
+		UpdateInterval: 6 * time.Hour,
+		DatasetTTL:     48 * time.Hour,
+	}
+}
+
+// LoadConfig loads configuration from environment variables, falling back to defaults.
+func LoadConfig() *Config {
+	cfg := DefaultConfig()
+
+	if v := os.Getenv("PREDICTOR_DATA_DIR"); v != "" {
+		cfg.DataDir = v
+	}
+	if v := os.Getenv("PREDICTOR_DOWNLOAD_PARALLEL"); v != "" {
+		if n, err := strconv.Atoi(v); err == nil && n > 0 {
+			cfg.Parallel = n
+		}
+	}
+	if v := os.Getenv("PREDICTOR_UPDATE_INTERVAL"); v != "" {
+		if d, err := time.ParseDuration(v); err == nil {
+			cfg.UpdateInterval = d
+		}
+	}
+	if v := os.Getenv("PREDICTOR_DATASET_TTL"); v != "" {
+		if d, err := time.ParseDuration(v); err == nil {
+			cfg.DatasetTTL = d
+		}
+	}
+
+	return cfg
+}

internal/downloader/downloader.go

@@ -0,0 +1,380 @@
+package downloader
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"math"
+	"net/http"
+	"os"
+	"path/filepath"
+	"time"
+
+	"predictor-refactored/internal/dataset"
+
+	"github.com/nilsmagnus/grib/griblib"
+	"go.uber.org/zap"
+	"golang.org/x/sync/errgroup"
+)
+
+// Downloader handles fetching GFS forecast data from S3 and assembling dataset files.
+type Downloader struct {
+	cfg    *Config
+	client *http.Client
+	log    *zap.Logger
+}
+
+// NewDownloader creates a new Downloader.
+func NewDownloader(cfg *Config, log *zap.Logger) *Downloader {
+	return &Downloader{
+		cfg: cfg,
+		client: &http.Client{
+			Timeout: 2 * time.Minute,
+		},
+		log: log,
+	}
+}
+
+// neededVariables is the set of GRIB variable names we need.
+var neededVariables = map[string]bool{
+	"HGT":  true,
+	"UGRD": true,
+	"VGRD": true,
+}
+
+// FindLatestRun finds the most recent available GFS model run on S3.
+// It checks the last forecast step of each run to confirm availability.
+func (d *Downloader) FindLatestRun(ctx context.Context) (time.Time, error) {
+	now := time.Now().UTC()
+	hour := now.Hour() - (now.Hour() % 6)
+	current := time.Date(now.Year(), now.Month(), now.Day(), hour, 0, 0, 0, time.UTC)
+
+	for i := 0; i < 8; i++ {
+		date := current.Format("20060102")
+		url := dataset.GribURL(date, current.Hour(), dataset.MaxHour) + ".idx"
+
+		req, err := http.NewRequestWithContext(ctx, http.MethodHead, url, nil)
+		if err != nil {
+			current = current.Add(-6 * time.Hour)
+			continue
+		}
+
+		resp, err := d.client.Do(req)
+		if err == nil {
+			resp.Body.Close()
+			if resp.StatusCode == http.StatusOK {
+				d.log.Info("found latest model run",
+					zap.Time("run", current),
+					zap.String("verified_url", url))
+				return current, nil
+			}
+		}
+
+		current = current.Add(-6 * time.Hour)
+	}
+
+	return time.Time{}, fmt.Errorf("no recent GFS forecast found (checked 8 runs)")
+}
+
+// Download downloads a complete forecast and assembles a dataset file.
+// Returns the path to the completed dataset file.
+func (d *Downloader) Download(ctx context.Context, run time.Time) (string, error) {
+	date := run.Format("20060102")
+	runHour := run.Hour()
+
+	finalPath := filepath.Join(d.cfg.DataDir, run.Format("2006010215"))
+	tempPath := finalPath + ".downloading"
+
+	// Check if final dataset already exists
+	if info, err := os.Stat(finalPath); err == nil && info.Size() == dataset.DatasetSize {
+		d.log.Info("dataset already exists", zap.String("path", finalPath))
+		return finalPath, nil
+	}
+
+	d.log.Info("starting dataset download",
+		zap.Time("run", run),
+		zap.String("temp_path", tempPath))
+
+	// Create the dataset file
+	ds, err := dataset.Create(tempPath)
+	if err != nil {
+		return "", fmt.Errorf("create dataset: %w", err)
+	}
+	defer ds.Close()
+
+	steps := dataset.Hours()
+	totalSteps := len(steps) * 2 // pgrb2 + pgrb2b per step
+	completed := 0
+
+	// Process each forecast step with bounded concurrency
+	g, ctx := errgroup.WithContext(ctx)
+	sem := make(chan struct{}, d.cfg.Parallel)
+
+	for _, step := range steps {
+		step := step
+		hourIdx := dataset.HourIndex(step)
+		if hourIdx < 0 {
+			continue
+		}
+
+		// Download pgrb2 (level set A)
+		sem <- struct{}{}
+		g.Go(func() error {
+			defer func() { <-sem }()
+			url := dataset.GribURL(date, runHour, step)
+			err := d.DownloadAndBlit(ctx, ds, url, hourIdx, dataset.LevelSetA)
+			if err != nil {
+				return fmt.Errorf("step %d pgrb2: %w", step, err)
+			}
+			completed++
+			d.log.Debug("step complete",
+				zap.Int("step", step),
+				zap.String("set", "pgrb2"),
+				zap.Int("progress", completed),
+				zap.Int("total", totalSteps))
+			return nil
+		})
+
+		// Download pgrb2b (level set B)
+		sem <- struct{}{}
+		g.Go(func() error {
+			defer func() { <-sem }()
+			url := dataset.GribURLB(date, runHour, step)
+			err := d.DownloadAndBlit(ctx, ds, url, hourIdx, dataset.LevelSetB)
+			if err != nil {
+				return fmt.Errorf("step %d pgrb2b: %w", step, err)
+			}
+			completed++
+			d.log.Debug("step complete",
+				zap.Int("step", step),
+				zap.String("set", "pgrb2b"),
+				zap.Int("progress", completed),
+				zap.Int("total", totalSteps))
+			return nil
+		})
+	}
+
+	if err := g.Wait(); err != nil {
+		os.Remove(tempPath)
+		return "", err
+	}
+
+	// Flush to disk
+	if err := ds.Flush(); err != nil {
+		os.Remove(tempPath)
+		return "", fmt.Errorf("flush dataset: %w", err)
+	}
+
+	// Close before rename
+	ds.Close()
+
+	// Atomic rename
+	if err := os.Rename(tempPath, finalPath); err != nil {
+		os.Remove(tempPath)
+		return "", fmt.Errorf("rename dataset: %w", err)
+	}
+
+	d.log.Info("dataset download complete", zap.String("path", finalPath))
+	return finalPath, nil
+}
+
+// DownloadAndBlit downloads needed GRIB fields from a URL and writes them into the dataset.
+func (d *Downloader) DownloadAndBlit(ctx context.Context, ds *dataset.File, baseURL string, hourIdx int, levelSet dataset.LevelSet) error {
+	// 1. Download .idx
+	idxURL := baseURL + ".idx"
+	idxBody, err := d.httpGet(ctx, idxURL)
+	if err != nil {
+		return fmt.Errorf("download idx: %w", err)
+	}
+
+	// 2. Parse and filter
+	entries := ParseIdx(idxBody)
+	filtered := FilterIdx(entries, neededVariables)
+
+	// Further filter to only levels in this level set
+	var relevant []IdxEntry
+	for _, e := range filtered {
+		ls, ok := dataset.PressureLevelSet(e.LevelMB)
+		if ok && ls == levelSet {
+			relevant = append(relevant, e)
+		}
+	}
+
+	if len(relevant) == 0 {
+		d.log.Warn("no relevant entries found in idx",
+			zap.String("url", idxURL),
+			zap.Int("total_entries", len(entries)),
+			zap.Int("filtered", len(filtered)))
+		return nil
+	}
+
+	// 3. Download byte ranges and write to temp file
+	ranges := EntriesToRanges(relevant)
+	tmpFile, err := d.downloadRangesToTempFile(ctx, baseURL, ranges)
+	if err != nil {
+		return fmt.Errorf("download ranges: %w", err)
+	}
+	defer os.Remove(tmpFile)
+
+	// 4. Read GRIB messages from temp file
+	f, err := os.Open(tmpFile)
+	if err != nil {
+		return fmt.Errorf("open temp grib: %w", err)
+	}
+
+	messages, err := griblib.ReadMessages(f)
+	f.Close()
+	if err != nil {
+		return fmt.Errorf("read grib messages: %w", err)
+	}
+
+	// 5. Decode and blit each message into the dataset
+	for _, msg := range messages {
+		if msg.Section4.ProductDefinitionTemplateNumber != 0 {
+			continue
+		}
+
+		product := msg.Section4.ProductDefinitionTemplate
+
+		varIdx := dataset.VariableIndex(int(product.ParameterCategory), int(product.ParameterNumber))
+		if varIdx < 0 {
+			continue
+		}
+
+		if product.FirstSurface.Type != 100 { // isobaric surface
+			continue
+		}
+
+		pressurePa := float64(product.FirstSurface.Value)
+		pressureMB := int(math.Round(pressurePa / 100.0))
+		levelIdx := dataset.PressureIndex(pressureMB)
+		if levelIdx < 0 {
+			continue
+		}
+
+		data := msg.Data()
+		if err := ds.BlitGribData(hourIdx, levelIdx, varIdx, data); err != nil {
+			d.log.Warn("blit failed",
+				zap.Int("var", varIdx),
+				zap.Int("level_mb", pressureMB),
+				zap.Error(err))
+			continue
+		}
+	}
+
+	return nil
+}
+
+// downloadRangesToTempFile downloads multiple byte ranges from a URL,
+// concatenating them into a single temp file (valid concatenated GRIB messages).
+func (d *Downloader) downloadRangesToTempFile(ctx context.Context, baseURL string, ranges []ByteRange) (string, error) {
+	tmpFile, err := os.CreateTemp(d.cfg.DataDir, "grib-*.tmp")
+	if err != nil {
+		return "", fmt.Errorf("create temp file: %w", err)
+	}
+	tmpPath := tmpFile.Name()
+
+	for _, r := range ranges {
+		data, err := d.httpGetRange(ctx, baseURL, r.Start, r.End)
+		if err != nil {
+			tmpFile.Close()
+			os.Remove(tmpPath)
+			return "", fmt.Errorf("download range %d-%d: %w", r.Start, r.End, err)
+		}
+		if _, err := tmpFile.Write(data); err != nil {
+			tmpFile.Close()
+			os.Remove(tmpPath)
+			return "", fmt.Errorf("write temp: %w", err)
+		}
+	}
+
+	if err := tmpFile.Close(); err != nil {
+		os.Remove(tmpPath)
+		return "", err
+	}
+
+	return tmpPath, nil
+}
+
+// httpGet downloads a URL and returns the body bytes.
+func (d *Downloader) httpGet(ctx context.Context, url string) ([]byte, error) {
+	var lastErr error
+	for attempt := 0; attempt < 3; attempt++ {
+		if attempt > 0 {
+			select {
+			case <-time.After(time.Duration(attempt*2) * time.Second):
+			case <-ctx.Done():
+				return nil, ctx.Err()
+			}
+		}
+
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+		if err != nil {
+			return nil, err
+		}
+
+		resp, err := d.client.Do(req)
+		if err != nil {
+			lastErr = err
+			continue
+		}
+
+		body, err := io.ReadAll(resp.Body)
+		resp.Body.Close()
+
+		if resp.StatusCode != http.StatusOK {
+			lastErr = fmt.Errorf("HTTP %d for %s", resp.StatusCode, url)
+			continue
+		}
+		if err != nil {
+			lastErr = err
+			continue
+		}
+
+		return body, nil
+	}
+
+	return nil, fmt.Errorf("after 3 attempts: %w", lastErr)
+}
+
+// httpGetRange downloads a byte range from a URL.
+func (d *Downloader) httpGetRange(ctx context.Context, url string, start, end int64) ([]byte, error) {
+	var lastErr error
+	for attempt := 0; attempt < 3; attempt++ {
+		if attempt > 0 {
+			select {
+			case <-time.After(time.Duration(attempt*2) * time.Second):
+			case <-ctx.Done():
+				return nil, ctx.Err()
+			}
+		}
+
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+		if err != nil {
+			return nil, err
+		}
+		req.Header.Set("Range", fmt.Sprintf("bytes=%d-%d", start, end))
+
+		resp, err := d.client.Do(req)
+		if err != nil {
+			lastErr = err
+			continue
+		}
+
+		body, err := io.ReadAll(resp.Body)
+		resp.Body.Close()
+
+		if resp.StatusCode != http.StatusPartialContent && resp.StatusCode != http.StatusOK {
+			lastErr = fmt.Errorf("HTTP %d for range %d-%d of %s", resp.StatusCode, start, end, url)
+			continue
+		}
+		if err != nil {
+			lastErr = err
+			continue
+		}
+
+		return body, nil
+	}
+
+	return nil, fmt.Errorf("after 3 attempts: %w", lastErr)
+}

internal/downloader/idx.go

@@ -0,0 +1,157 @@
+package downloader
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// IdxEntry represents a single parsed line from a GRIB .idx file.
+// Example line: "15:1207405:d=2024010100:HGT:1000 mb:0 hour fcst:"
+type IdxEntry struct {
+	Index     int
+	Offset    int64
+	Variable  string // "HGT", "UGRD", "VGRD", etc.
+	LevelMB   int    // pressure level in mb (0 if not a pressure level)
+	Hour      int    // forecast hour
+	EndOffset int64  // byte after this message (from next entry's offset, or -1 if last)
+}
+
+// Length returns the byte length of this GRIB message, or -1 if unknown.
+func (e *IdxEntry) Length() int64 {
+	if e.EndOffset <= 0 {
+		return -1
+	}
+	return e.EndOffset - e.Offset
+}
+
+// ParseIdx parses a .idx file body and returns all entries.
+// Lines that can't be parsed are silently skipped.
+func ParseIdx(body []byte) []IdxEntry {
+	lines := strings.Split(string(body), "\n")
+	var entries []IdxEntry
+
+	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+
+		parts := strings.Split(line, ":")
+		if len(parts) < 7 {
+			continue
+		}
+
+		idx, err := strconv.Atoi(parts[0])
+		if err != nil {
+			continue
+		}
+
+		offset, err := strconv.ParseInt(parts[1], 10, 64)
+		if err != nil {
+			continue
+		}
+
+		variable := parts[3]
+		levelStr := parts[4]
+		hourStr := parts[5]
+
+		levelMB := parseLevelMB(levelStr)
+		hour := parseHour(hourStr)
+
+		entries = append(entries, IdxEntry{
+			Index:     idx,
+			Offset:    offset,
+			Variable:  variable,
+			LevelMB:   levelMB,
+			Hour:      hour,
+			EndOffset: -1, // filled in below
+		})
+	}
+
+	// Fill in EndOffset from the next entry's Offset.
+	for i := 0; i < len(entries)-1; i++ {
+		entries[i].EndOffset = entries[i+1].Offset
+	}
+
+	return entries
+}
+
+// FilterIdx returns entries matching the given variables at pressure levels.
+// Only entries with a recognized pressure level (levelMB > 0) are returned.
+func FilterIdx(entries []IdxEntry, variables map[string]bool) []IdxEntry {
+	var filtered []IdxEntry
+	for _, e := range entries {
+		if !variables[e.Variable] {
+			continue
+		}
+		if e.LevelMB <= 0 {
+			continue
+		}
+		// Must have a known length (not the last entry) or be handled specially
+		if e.Length() <= 0 {
+			continue
+		}
+		filtered = append(filtered, e)
+	}
+	return filtered
+}
+
+// parseLevelMB parses a level string like "1000 mb" and returns the pressure in mb.
+// Returns 0 if not a pressure level.
+func parseLevelMB(s string) int {
+	s = strings.TrimSpace(s)
+	if !strings.HasSuffix(s, " mb") {
+		return 0
+	}
+	numStr := strings.TrimSuffix(s, " mb")
+	n, err := strconv.Atoi(numStr)
+	if err != nil {
+		return 0
+	}
+	return n
+}
+
+// parseHour parses a forecast hour string like "0 hour fcst" or "anl".
+// Returns -1 if it can't be parsed.
+func parseHour(s string) int {
+	s = strings.TrimSpace(s)
+	if s == "anl" {
+		return 0
+	}
+	s = strings.TrimSuffix(s, " hour fcst")
+	n, err := strconv.Atoi(s)
+	if err != nil {
+		return -1
+	}
+	return n
+}
+
+// GroupByRange groups idx entries into byte ranges suitable for HTTP Range downloads.
+// Each range covers one contiguous GRIB message.
+type ByteRange struct {
+	Start int64
+	End   int64 // inclusive
+	Entry IdxEntry
+}
+
+// EntriesToRanges converts filtered idx entries to byte ranges.
+func EntriesToRanges(entries []IdxEntry) []ByteRange {
+	ranges := make([]ByteRange, 0, len(entries))
+	for _, e := range entries {
+		if e.Length() <= 0 {
+			continue
+		}
+		ranges = append(ranges, ByteRange{
+			Start: e.Offset,
+			End:   e.EndOffset - 1, // inclusive
+			Entry: e,
+		})
+	}
+	return ranges
+}
+
+// FormatRange returns an HTTP Range header value for a byte range.
+func (r ByteRange) FormatRange() string {
+	return fmt.Sprintf("bytes=%d-%d", r.Start, r.End)
+}

internal/downloader/idx_test.go

@@ -0,0 +1,110 @@
+package downloader
+
+import (
+	"testing"
+)
+
+const sampleIdx = `1:0:d=2024010100:HGT:1000 mb:0 hour fcst:
+2:289012:d=2024010100:HGT:975 mb:0 hour fcst:
+3:541876:d=2024010100:TMP:1000 mb:0 hour fcst:
+4:789012:d=2024010100:UGRD:1000 mb:0 hour fcst:
+5:1045678:d=2024010100:VGRD:1000 mb:0 hour fcst:
+6:1298765:d=2024010100:UGRD:975 mb:0 hour fcst:
+7:1567890:d=2024010100:UGRD:2 m above ground:0 hour fcst:
+8:1812345:d=2024010100:VGRD:975 mb:0 hour fcst:
+9:2098765:d=2024010100:HGT:500 mb:3 hour fcst:
+`
+
+func TestParseIdx(t *testing.T) {
+	entries := ParseIdx([]byte(sampleIdx))
+	if len(entries) != 9 {
+		t.Fatalf("expected 9 entries, got %d", len(entries))
+	}
+
+	// Check first entry
+	e := entries[0]
+	if e.Index != 1 || e.Offset != 0 || e.Variable != "HGT" || e.LevelMB != 1000 || e.Hour != 0 {
+		t.Errorf("entry 0: got %+v", e)
+	}
+	if e.EndOffset != 289012 {
+		t.Errorf("entry 0 EndOffset: got %d, want 289012", e.EndOffset)
+	}
+
+	// Check "2 m above ground" is not a pressure level
+	e = entries[6] // UGRD at "2 m above ground"
+	if e.LevelMB != 0 {
+		t.Errorf("non-pressure level should have LevelMB=0, got %d", e.LevelMB)
+	}
+
+	// Last entry should have EndOffset = -1
+	last := entries[len(entries)-1]
+	if last.EndOffset != -1 {
+		t.Errorf("last entry EndOffset: got %d, want -1", last.EndOffset)
+	}
+}
+
+func TestFilterIdx(t *testing.T) {
+	entries := ParseIdx([]byte(sampleIdx))
+	filtered := FilterIdx(entries, neededVariables)
+
+	// Should include HGT/UGRD/VGRD at pressure levels, exclude TMP and "above ground"
+	// And exclude last entry (no EndOffset)
+	for _, e := range filtered {
+		if !neededVariables[e.Variable] {
+			t.Errorf("unexpected variable %s", e.Variable)
+		}
+		if e.LevelMB <= 0 {
+			t.Errorf("non-pressure level included: %+v", e)
+		}
+		if e.Length() <= 0 {
+			t.Errorf("entry with unknown length included: %+v", e)
+		}
+	}
+
+	// Count expected: HGT@1000, HGT@975, UGRD@1000, VGRD@1000, UGRD@975, VGRD@975 = 6
+	// But HGT@500 at 3hr fcst is the last entry (no EndOffset), so excluded
+	if len(filtered) != 6 {
+		t.Errorf("expected 6 filtered entries, got %d", len(filtered))
+		for _, e := range filtered {
+			t.Logf("  %s %d mb (offset %d, len %d)", e.Variable, e.LevelMB, e.Offset, e.Length())
+		}
+	}
+}
+
+func TestParseLevelMB(t *testing.T) {
+	tests := []struct {
+		input string
+		want  int
+	}{
+		{"1000 mb", 1000},
+		{"975 mb", 975},
+		{"1 mb", 1},
+		{"2 m above ground", 0},
+		{"surface", 0},
+		{"tropopause", 0},
+	}
+	for _, tt := range tests {
+		got := parseLevelMB(tt.input)
+		if got != tt.want {
+			t.Errorf("parseLevelMB(%q) = %d, want %d", tt.input, got, tt.want)
+		}
+	}
+}
+
+func TestParseHour(t *testing.T) {
+	tests := []struct {
+		input string
+		want  int
+	}{
+		{"0 hour fcst", 0},
+		{"3 hour fcst", 3},
+		{"192 hour fcst", 192},
+		{"anl", 0},
+	}
+	for _, tt := range tests {
+		got := parseHour(tt.input)
+		if got != tt.want {
+			t.Errorf("parseHour(%q) = %d, want %d", tt.input, got, tt.want)
+		}
+	}
+}

internal/elevation/elevation.go

@@ -0,0 +1,113 @@
+package elevation
+
+import (
+	"encoding/binary"
+	"fmt"
+	"math"
+	"os"
+
+	mmap "github.com/edsrzf/mmap-go"
+)
+
+// Dataset provides global elevation lookup, compatible with ruaumoko.
+// Binary format: int16 little-endian elevation values in metres, row-major (lat, lon).
+// Latitude axis: -90 to +90 (south to north), Longitude axis: 0 to 360 (wraps).
+// Resolution: 120 cells per degree (30 arc-seconds).
+const (
+	CellsPerDegree = 120
+	NumLats        = 180*CellsPerDegree + 1 // 21601
+	NumLons        = 360 * CellsPerDegree    // 43200
+	DataSize       = NumLats * NumLons * 2   // 1,866,326,400 bytes (~1.74 GiB)
+)
+
+// Dataset is a memory-mapped global elevation grid.
+type Dataset struct {
+	mm   mmap.MMap
+	file *os.File
+}
+
+// Open opens an existing elevation dataset file.
+func Open(path string) (*Dataset, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, fmt.Errorf("open elevation: %w", err)
+	}
+
+	info, err := f.Stat()
+	if err != nil {
+		f.Close()
+		return nil, fmt.Errorf("stat elevation: %w", err)
+	}
+	if info.Size() != DataSize {
+		f.Close()
+		return nil, fmt.Errorf("elevation dataset should be %d bytes (was %d)", DataSize, info.Size())
+	}
+
+	mm, err := mmap.Map(f, mmap.RDONLY, 0)
+	if err != nil {
+		f.Close()
+		return nil, fmt.Errorf("mmap elevation: %w", err)
+	}
+
+	return &Dataset{mm: mm, file: f}, nil
+}
+
+// getCell reads the int16 elevation at grid indices (latIdx, lngIdx).
+func (d *Dataset) getCell(latIdx, lngIdx int) int16 {
+	// Clamp latitude
+	if latIdx < 0 {
+		latIdx = 0
+	}
+	if latIdx >= NumLats {
+		latIdx = NumLats - 1
+	}
+	// Wrap longitude
+	lngIdx = lngIdx % NumLons
+	if lngIdx < 0 {
+		lngIdx += NumLons
+	}
+
+	off := (latIdx*NumLons + lngIdx) * 2
+	return int16(binary.LittleEndian.Uint16(d.mm[off : off+2]))
+}
+
+// Get returns the interpolated elevation in metres at the given coordinates.
+// lat: -90 to +90, lng: 0 to 360 (or -180 to 180, will be normalised).
+func (d *Dataset) Get(lat, lng float64) float64 {
+	// Normalise longitude to [0, 360)
+	if lng < 0 {
+		lng += 360
+	}
+
+	// Convert to cell coordinates
+	latCell := (lat + 90.0) * CellsPerDegree
+	lngCell := lng * CellsPerDegree
+
+	lat0 := int(math.Floor(latCell))
+	lng0 := int(math.Floor(lngCell))
+	latFrac := latCell - float64(lat0)
+	lngFrac := lngCell - float64(lng0)
+
+	// Bilinear interpolation
+	v00 := float64(d.getCell(lat0, lng0))
+	v10 := float64(d.getCell(lat0+1, lng0))
+	v01 := float64(d.getCell(lat0, lng0+1))
+	v11 := float64(d.getCell(lat0+1, lng0+1))
+
+	return (1-latFrac)*((1-lngFrac)*v00+lngFrac*v01) +
+		latFrac*((1-lngFrac)*v10+lngFrac*v11)
+}
+
+// Close unmaps and closes the dataset.
+func (d *Dataset) Close() error {
+	if d.mm != nil {
+		d.mm.Unmap()
+		d.mm = nil
+	}
+	if d.file != nil {
+		err := d.file.Close()
+		d.file = nil
+		return err
+	}
+	return nil
+}

internal/prediction/interpolate.go

@@ -0,0 +1,153 @@
+package prediction
+
+import (
+	"fmt"
+
+	"predictor-refactored/internal/dataset"
+)
+
+// Exact port of the reference interpolation logic (interpolate.pyx).
+// 4D interpolation: time, latitude, longitude, altitude (via geopotential height).
+
+// lerp1 holds an index and interpolation weight for one axis.
+type lerp1 struct {
+	index int
+	lerp  float64
+}
+
+// lerp3 holds indices and a combined weight for the (hour, lat, lon) axes.
+type lerp3 struct {
+	hour, lat, lng int
+	lerp           float64
+}
+
+// RangeError indicates a coordinate is outside the dataset bounds.
+type RangeError struct {
+	Variable string
+	Value    float64
+}
+
+func (e *RangeError) Error() string {
+	return fmt.Sprintf("%s=%f out of range", e.Variable, e.Value)
+}
+
+// pick computes interpolation indices and weights for a single axis.
+// left: axis start, step: axis spacing, n: number of points, value: query value.
+// Returns two lerp1 values (lower and upper bracket).
+func pick(left, step float64, n int, value float64, variableName string) ([2]lerp1, error) {
+	a := (value - left) / step
+	b := int(a) // truncation toward zero, same as Cython <long> cast
+	if b < 0 || b >= n-1 {
+		return [2]lerp1{}, &RangeError{Variable: variableName, Value: value}
+	}
+	l := a - float64(b)
+	return [2]lerp1{
+		{index: b, lerp: 1 - l},
+		{index: b + 1, lerp: l},
+	}, nil
+}
+
+// pick3 computes 8 trilinear interpolation weights for (hour, lat, lng).
+func pick3(hour, lat, lng float64) ([8]lerp3, error) {
+	lhour, err := pick(0, 3, 65, hour, "hour")
+	if err != nil {
+		return [8]lerp3{}, err
+	}
+	llat, err := pick(-90, 0.5, 361, lat, "lat")
+	if err != nil {
+		return [8]lerp3{}, err
+	}
+	// Longitude wraps: tell pick the axis is one larger, then wrap index 720 → 0
+	llng, err := pick(0, 0.5, 720+1, lng, "lng")
+	if err != nil {
+		return [8]lerp3{}, err
+	}
+	if llng[1].index == 720 {
+		llng[1].index = 0
+	}
+
+	var out [8]lerp3
+	i := 0
+	for _, a := range lhour {
+		for _, b := range llat {
+			for _, c := range llng {
+				out[i] = lerp3{
+					hour: a.index,
+					lat:  b.index,
+					lng:  c.index,
+					lerp: a.lerp * b.lerp * c.lerp,
+				}
+				i++
+			}
+		}
+	}
+	return out, nil
+}
+
+// interp3 performs 8-point weighted interpolation at a given variable and pressure level.
+func interp3(ds *dataset.File, lerps [8]lerp3, variable, level int) float64 {
+	var r float64
+	for i := 0; i < 8; i++ {
+		v := ds.Val(lerps[i].hour, level, variable, lerps[i].lat, lerps[i].lng)
+		r += float64(v) * lerps[i].lerp
+	}
+	return r
+}
+
+// search finds the largest pressure level index where interpolated geopotential
+// height is less than the target altitude. Searches levels 0..45 (excludes topmost).
+func search(ds *dataset.File, lerps [8]lerp3, target float64) int {
+	lower, upper := 0, 45
+
+	for lower < upper {
+		mid := (lower + upper + 1) / 2
+		test := interp3(ds, lerps, dataset.VarHeight, mid)
+		if target <= test {
+			upper = mid - 1
+		} else {
+			lower = mid
+		}
+	}
+
+	return lower
+}
+
+// interp4 performs altitude-interpolated wind lookup using two bracketing levels.
+func interp4(ds *dataset.File, lerps [8]lerp3, altLerp lerp1, variable int) float64 {
+	lower := interp3(ds, lerps, variable, altLerp.index)
+	upper := interp3(ds, lerps, variable, altLerp.index+1)
+	return lower*altLerp.lerp + upper*(1-altLerp.lerp)
+}
+
+// GetWind returns interpolated (u, v) wind components for the given position.
+// hour: fractional hours since dataset start.
+// lat: latitude in degrees (-90 to +90).
+// lng: longitude in degrees (0 to 360).
+// alt: altitude in metres above sea level.
+func GetWind(ds *dataset.File, warnings *Warnings, hour, lat, lng, alt float64) (u, v float64, err error) {
+	lerps, err := pick3(hour, lat, lng)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	altidx := search(ds, lerps, alt)
+	lower := interp3(ds, lerps, dataset.VarHeight, altidx)
+	upper := interp3(ds, lerps, dataset.VarHeight, altidx+1)
+
+	var altLerp float64
+	if lower != upper {
+		altLerp = (upper - alt) / (upper - lower)
+	} else {
+		altLerp = 0.5
+	}
+
+	if altLerp < 0 {
+		warnings.AltitudeTooHigh.Add(1)
+	}
+
+	alt1 := lerp1{index: altidx, lerp: altLerp}
+	u = interp4(ds, lerps, alt1, dataset.VarWindU)
+	v = interp4(ds, lerps, alt1, dataset.VarWindV)
+
+	return u, v, nil
+}

internal/prediction/models.go

@@ -0,0 +1,188 @@
+package prediction
+
+import (
+	"math"
+	"time"
+
+	"predictor-refactored/internal/dataset"
+	"predictor-refactored/internal/elevation"
+)
+
+// Exact port of the reference flight models (models.py).
+
+const (
+	pi180 = math.Pi / 180.0
+	_180pi = 180.0 / math.Pi
+)
+
+// --- Up/Down Models ---
+
+// ConstantAscent returns a model with constant vertical velocity (m/s).
+func ConstantAscent(ascentRate float64) Model {
+	return func(t, lat, lng, alt float64) (dlat, dlng, dalt float64) {
+		return 0, 0, ascentRate
+	}
+}
+
+// DragDescent returns a descent-under-parachute model.
+// seaLevelDescentRate is the descent rate at sea level (m/s, positive value).
+// Uses the NASA atmosphere model for density at altitude.
+func DragDescent(seaLevelDescentRate float64) Model {
+	dragCoefficient := seaLevelDescentRate * 1.1045
+
+	return func(t, lat, lng, alt float64) (dlat, dlng, dalt float64) {
+		return 0, 0, -dragCoefficient / math.Sqrt(nasaDensity(alt))
+	}
+}
+
+// nasaDensity computes air density using the NASA atmosphere model.
+// Reference: http://www.grc.nasa.gov/WWW/K-12/airplane/atmosmet.html
+func nasaDensity(alt float64) float64 {
+	var temp, pressure float64
+
+	switch {
+	case alt > 25000:
+		temp = -131.21 + 0.00299*alt
+		pressure = 2.488 * math.Pow((temp+273.1)/216.6, -11.388)
+	case alt > 11000:
+		temp = -56.46
+		pressure = 22.65 * math.Exp(1.73-0.000157*alt)
+	default:
+		temp = 15.04 - 0.00649*alt
+		pressure = 101.29 * math.Pow((temp+273.1)/288.08, 5.256)
+	}
+
+	return pressure / (0.2869 * (temp + 273.1))
+}
+
+// --- Sideways Models ---
+
+// WindVelocity returns a model that gives lateral movement at the wind velocity.
+// ds is the wind dataset, dsEpoch is the dataset start time as UNIX timestamp.
+func WindVelocity(ds *dataset.File, dsEpoch float64, warnings *Warnings) Model {
+	return func(t, lat, lng, alt float64) (dlat, dlng, dalt float64) {
+		tHours := (t - dsEpoch) / 3600.0
+		u, v, err := GetWind(ds, warnings, tHours, lat, lng, alt)
+		if err != nil {
+			return 0, 0, 0
+		}
+
+		R := 6371009.0 + alt
+		dlat = _180pi * v / R
+		dlng = _180pi * u / (R * math.Cos(lat*pi180))
+		return dlat, dlng, 0
+	}
+}
+
+// --- Model Combinations ---
+
+// LinearModel returns a model that sums all component models.
+func LinearModel(models ...Model) Model {
+	return func(t, lat, lng, alt float64) (dlat, dlng, dalt float64) {
+		for _, m := range models {
+			d1, d2, d3 := m(t, lat, lng, alt)
+			dlat += d1
+			dlng += d2
+			dalt += d3
+		}
+		return
+	}
+}
+
+// --- Termination Criteria ---
+
+// BurstTermination returns a terminator that fires when altitude >= burstAltitude.
+func BurstTermination(burstAltitude float64) Terminator {
+	return func(t, lat, lng, alt float64) bool {
+		return alt >= burstAltitude
+	}
+}
+
+// SeaLevelTermination fires when altitude <= 0.
+func SeaLevelTermination(t, lat, lng, alt float64) bool {
+	return alt <= 0
+}
+
+// TimeTermination returns a terminator that fires when t > maxTime.
+func TimeTermination(maxTime float64) Terminator {
+	return func(t, lat, lng, alt float64) bool {
+		return t > maxTime
+	}
+}
+
+// ElevationTermination returns a terminator that fires when alt < ground level.
+// Uses ruaumoko-compatible elevation data. Longitude is normalised internally.
+func ElevationTermination(elev *elevation.Dataset) Terminator {
+	return func(t, lat, lng, alt float64) bool {
+		return elev.Get(lat, lng) > alt
+	}
+}
+
+// --- Pre-Defined Profiles ---
+
+// Stage pairs a model with its termination criterion.
+type Stage struct {
+	Model      Model
+	Terminator Terminator
+}
+
+// StandardProfile creates the chain for a standard high-altitude balloon flight:
+// ascent at constant rate → burst → descent under parachute.
+// If elev is non-nil, descent terminates at ground level; otherwise at sea level.
+func StandardProfile(ascentRate, burstAltitude, descentRate float64,
+	ds *dataset.File, dsEpoch float64, warnings *Warnings,
+	elev *elevation.Dataset) []Stage {
+
+	wind := WindVelocity(ds, dsEpoch, warnings)
+
+	modelUp := LinearModel(ConstantAscent(ascentRate), wind)
+	termUp := BurstTermination(burstAltitude)
+
+	modelDown := LinearModel(DragDescent(descentRate), wind)
+	var termDown Terminator
+	if elev != nil {
+		termDown = ElevationTermination(elev)
+	} else {
+		termDown = Terminator(SeaLevelTermination)
+	}
+
+	return []Stage{
+		{Model: modelUp, Terminator: termUp},
+		{Model: modelDown, Terminator: termDown},
+	}
+}
+
+// FloatProfile creates the chain for a floating balloon flight:
+// ascent to float altitude → float until stop time.
+func FloatProfile(ascentRate, floatAltitude float64, stopTime time.Time,
+	ds *dataset.File, dsEpoch float64, warnings *Warnings) []Stage {
+
+	wind := WindVelocity(ds, dsEpoch, warnings)
+
+	modelUp := LinearModel(ConstantAscent(ascentRate), wind)
+	termUp := BurstTermination(floatAltitude)
+
+	modelFloat := wind
+	termFloat := TimeTermination(float64(stopTime.Unix()))
+
+	return []Stage{
+		{Model: modelUp, Terminator: termUp},
+		{Model: modelFloat, Terminator: termFloat},
+	}
+}
+
+// RunPrediction runs a prediction with the given profile stages.
+// launchTime is a UNIX timestamp.
+func RunPrediction(launchTime float64, lat, lng, alt float64, stages []Stage) []StageResult {
+	chain := make([]struct {
+		Model      Model
+		Terminator Terminator
+	}, len(stages))
+
+	for i, s := range stages {
+		chain[i].Model = s.Model
+		chain[i].Terminator = s.Terminator
+	}
+
+	return Solve(launchTime, lat, lng, alt, chain)
+}

internal/prediction/solver.go

@@ -0,0 +1,180 @@
+package prediction
+
+import "math"
+
+// Exact port of the reference RK4 solver (solver.pyx).
+// Integrates balloon state using RK4 with dt=60 seconds.
+// Termination uses binary search refinement (tolerance 0.01).
+
+// Vec holds the balloon state: latitude, longitude, altitude.
+type Vec struct {
+	Lat float64
+	Lng float64
+	Alt float64
+}
+
+// Model is a function that returns (dlat/dt, dlng/dt, dalt/dt) given state.
+// t is UNIX timestamp, lat/lng in degrees, alt in metres.
+type Model func(t float64, lat, lng, alt float64) (dlat, dlng, dalt float64)
+
+// Terminator returns true when integration should stop.
+type Terminator func(t float64, lat, lng, alt float64) bool
+
+// StageResult holds the trajectory points for one flight stage.
+type StageResult struct {
+	Points []TrajectoryPoint
+}
+
+// TrajectoryPoint is a single point in a trajectory (used by solver).
+type TrajectoryPoint struct {
+	T   float64 // UNIX timestamp
+	Lat float64
+	Lng float64
+	Alt float64
+}
+
+// pymod returns a % b with Python semantics (always non-negative when b > 0).
+func pymod(a, b float64) float64 {
+	r := math.Mod(a, b)
+	if r < 0 {
+		r += b
+	}
+	return r
+}
+
+// vecadd returns a + k*b, with lng wrapped to [0, 360).
+func vecadd(a Vec, k float64, b Vec) Vec {
+	return Vec{
+		Lat: a.Lat + k*b.Lat,
+		Lng: pymod(a.Lng+k*b.Lng, 360.0),
+		Alt: a.Alt + k*b.Alt,
+	}
+}
+
+// scalarLerp returns (1-l)*a + l*b.
+func scalarLerp(a, b, l float64) float64 {
+	return (1-l)*a + l*b
+}
+
+// lngLerp interpolates longitude handling the 0/360 wrap-around.
+func lngLerp(a, b, l float64) float64 {
+	l2 := 1 - l
+
+	if a > b {
+		a, b = b, a
+		l, l2 = l2, l
+	}
+
+	// distance round one way:  b - a
+	// distance around other:   (a + 360) - b
+	if b-a < 180.0 {
+		return l2*a + l*b
+	}
+	return pymod(l2*(a+360)+l*b, 360.0)
+}
+
+// vecLerp returns (1-l)*a + l*b with proper longitude wrapping.
+func vecLerp(a, b Vec, l float64) Vec {
+	return Vec{
+		Lat: scalarLerp(a.Lat, b.Lat, l),
+		Lng: lngLerp(a.Lng, b.Lng, l),
+		Alt: scalarLerp(a.Alt, b.Alt, l),
+	}
+}
+
+// rk4 integrates from initial conditions using RK4.
+// dt=60.0 seconds, terminationTolerance=0.01.
+func rk4(t float64, lat, lng, alt float64, model Model, terminator Terminator) []TrajectoryPoint {
+	const dt = 60.0
+	const terminationTolerance = 0.01
+
+	y := Vec{Lat: lat, Lng: lng, Alt: alt}
+	result := []TrajectoryPoint{{T: t, Lat: y.Lat, Lng: y.Lng, Alt: y.Alt}}
+
+	for {
+		// Evaluate model at 4 points (standard RK4)
+		k1lat, k1lng, k1alt := model(t, y.Lat, y.Lng, y.Alt)
+		k1 := Vec{Lat: k1lat, Lng: k1lng, Alt: k1alt}
+
+		mid1 := vecadd(y, dt/2, k1)
+		k2lat, k2lng, k2alt := model(t+dt/2, mid1.Lat, mid1.Lng, mid1.Alt)
+		k2 := Vec{Lat: k2lat, Lng: k2lng, Alt: k2alt}
+
+		mid2 := vecadd(y, dt/2, k2)
+		k3lat, k3lng, k3alt := model(t+dt/2, mid2.Lat, mid2.Lng, mid2.Alt)
+		k3 := Vec{Lat: k3lat, Lng: k3lng, Alt: k3alt}
+
+		end := vecadd(y, dt, k3)
+		k4lat, k4lng, k4alt := model(t+dt, end.Lat, end.Lng, end.Alt)
+		k4 := Vec{Lat: k4lat, Lng: k4lng, Alt: k4alt}
+
+		// y2 = y + dt/6*k1 + dt/3*k2 + dt/3*k3 + dt/6*k4
+		y2 := y
+		y2 = vecadd(y2, dt/6, k1)
+		y2 = vecadd(y2, dt/3, k2)
+		y2 = vecadd(y2, dt/3, k3)
+		y2 = vecadd(y2, dt/6, k4)
+
+		t2 := t + dt
+
+		if terminator(t2, y2.Lat, y2.Lng, y2.Alt) {
+			// Binary search to refine the termination point.
+			// Find l in [0, 1] such that (t3, y3) = lerp((t, y), (t2, y2), l)
+			// is near where the terminator fires.
+			left := 0.0
+			right := 1.0
+
+			var t3 float64
+			var y3 Vec
+			t3 = t2
+			y3 = y2
+
+			for right-left > terminationTolerance {
+				mid := (left + right) / 2
+				t3 = scalarLerp(t, t2, mid)
+				y3 = vecLerp(y, y2, mid)
+
+				if terminator(t3, y3.Lat, y3.Lng, y3.Alt) {
+					right = mid
+				} else {
+					left = mid
+				}
+			}
+
+			result = append(result, TrajectoryPoint{T: t3, Lat: y3.Lat, Lng: y3.Lng, Alt: y3.Alt})
+			break
+		}
+
+		// Update current state
+		t = t2
+		y = y2
+		result = append(result, TrajectoryPoint{T: t, Lat: y.Lat, Lng: y.Lng, Alt: y.Alt})
+	}
+
+	return result
+}
+
+// Solve runs through a chain of (model, terminator) stages.
+// Returns one StageResult per stage.
+func Solve(t, lat, lng, alt float64, chain []struct {
+	Model      Model
+	Terminator Terminator
+}) []StageResult {
+	var results []StageResult
+
+	for _, stage := range chain {
+		points := rk4(t, lat, lng, alt, stage.Model, stage.Terminator)
+		results = append(results, StageResult{Points: points})
+
+		// Next stage starts where this one ended
+		if len(points) > 0 {
+			last := points[len(points)-1]
+			t = last.T
+			lat = last.Lat
+			lng = last.Lng
+			alt = last.Alt
+		}
+	}
+
+	return results
+}

internal/prediction/warnings.go

@@ -0,0 +1,21 @@
+package prediction
+
+import "sync/atomic"
+
+// Warnings tracks warning conditions during a prediction run.
+type Warnings struct {
+	AltitudeTooHigh atomic.Int64
+}
+
+// ToMap returns warnings as a map suitable for JSON serialization.
+// Only includes warnings that have fired.
+func (w *Warnings) ToMap() map[string]any {
+	result := make(map[string]any)
+	if n := w.AltitudeTooHigh.Load(); n > 0 {
+		result["altitude_too_high"] = map[string]any{
+			"count":       n,
+			"description": "The altitude went too high, above the max forecast wind. Wind data will be unreliable",
+		}
+	}
+	return result
+}

internal/service/service.go

@@ -0,0 +1,245 @@
+package service
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+
+	"predictor-refactored/internal/dataset"
+	"predictor-refactored/internal/downloader"
+	"predictor-refactored/internal/elevation"
+
+	"go.uber.org/zap"
+)
+
+// Service orchestrates the dataset lifecycle and provides prediction capabilities.
+type Service struct {
+	mu       sync.RWMutex
+	ds       *dataset.File
+	elev     *elevation.Dataset
+	cfg      *downloader.Config
+	dl       *downloader.Downloader
+	log      *zap.Logger
+	updating sync.Mutex // prevents concurrent downloads
+}
+
+// New creates a new Service.
+func New(cfg *downloader.Config, log *zap.Logger) *Service {
+	return &Service{
+		cfg: cfg,
+		dl:  downloader.NewDownloader(cfg, log),
+		log: log,
+	}
+}
+
+// LoadElevation loads the ruaumoko-compatible elevation dataset from path.
+// If the file doesn't exist, elevation termination is disabled (falls back to sea level).
+func (s *Service) LoadElevation(path string) {
+	ds, err := elevation.Open(path)
+	if err != nil {
+		s.log.Warn("elevation dataset not available, using sea-level termination",
+			zap.String("path", path), zap.Error(err))
+		return
+	}
+	s.elev = ds
+	s.log.Info("elevation dataset loaded", zap.String("path", path))
+}
+
+// Elevation returns the elevation dataset (may be nil).
+func (s *Service) Elevation() *elevation.Dataset {
+	return s.elev
+}
+
+// Ready returns true if the service has a loaded dataset.
+func (s *Service) Ready() bool {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return s.ds != nil
+}
+
+// DatasetTime returns the forecast time of the currently loaded dataset.
+func (s *Service) DatasetTime() (time.Time, bool) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	if s.ds == nil {
+		return time.Time{}, false
+	}
+	return s.ds.DSTime, true
+}
+
+// Dataset returns the current dataset for reading.
+func (s *Service) Dataset() *dataset.File {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return s.ds
+}
+
+// Update checks for and downloads new forecast data if needed.
+func (s *Service) Update(ctx context.Context) error {
+	if !s.updating.TryLock() {
+		s.log.Info("update already in progress, skipping")
+		return nil
+	}
+	defer s.updating.Unlock()
+
+	// Check if current dataset is still fresh
+	if dsTime, ok := s.DatasetTime(); ok {
+		if time.Since(dsTime) < s.cfg.DatasetTTL {
+			s.log.Info("dataset still fresh, skipping update",
+				zap.Time("dataset_time", dsTime),
+				zap.Duration("age", time.Since(dsTime)))
+			return nil
+		}
+	}
+
+	// Try loading an existing dataset from disk first
+	if err := s.loadExistingDataset(); err == nil {
+		return nil
+	}
+
+	// Find latest available model run
+	run, err := s.dl.FindLatestRun(ctx)
+	if err != nil {
+		return err
+	}
+
+	// Download and assemble
+	path, err := s.dl.Download(ctx, run)
+	if err != nil {
+		return err
+	}
+
+	// Open the new dataset
+	ds, err := dataset.Open(path, run)
+	if err != nil {
+		return err
+	}
+
+	// Swap in the new dataset
+	s.setDataset(ds)
+	s.log.Info("dataset loaded", zap.Time("run", run), zap.String("path", path))
+
+	// Clean old datasets
+	s.cleanOldDatasets(path)
+
+	return nil
+}
+
+// loadExistingDataset tries to find and load an existing dataset from the data directory.
+func (s *Service) loadExistingDataset() error {
+	entries, err := os.ReadDir(s.cfg.DataDir)
+	if err != nil {
+		return err
+	}
+
+	// Collect valid dataset files (name is YYYYMMDDHH, no extension, correct size)
+	type candidate struct {
+		name string
+		path string
+		run  time.Time
+	}
+	var candidates []candidate
+
+	for _, e := range entries {
+		if e.IsDir() || strings.Contains(e.Name(), ".") {
+			continue
+		}
+		if len(e.Name()) != 10 {
+			continue
+		}
+
+		run, err := time.Parse("2006010215", e.Name())
+		if err != nil {
+			continue
+		}
+
+		path := filepath.Join(s.cfg.DataDir, e.Name())
+		info, err := os.Stat(path)
+		if err != nil || info.Size() != dataset.DatasetSize {
+			continue
+		}
+
+		if time.Since(run) > s.cfg.DatasetTTL {
+			continue
+		}
+
+		candidates = append(candidates, candidate{name: e.Name(), path: path, run: run})
+	}
+
+	if len(candidates) == 0 {
+		return os.ErrNotExist
+	}
+
+	// Pick the newest
+	sort.Slice(candidates, func(i, j int) bool {
+		return candidates[i].run.After(candidates[j].run)
+	})
+
+	best := candidates[0]
+	ds, err := dataset.Open(best.path, best.run)
+	if err != nil {
+		return err
+	}
+
+	s.setDataset(ds)
+	s.log.Info("loaded existing dataset",
+		zap.Time("run", best.run),
+		zap.String("path", best.path))
+	return nil
+}
+
+// setDataset swaps the current dataset with a new one, closing the old one.
+func (s *Service) setDataset(ds *dataset.File) {
+	s.mu.Lock()
+	old := s.ds
+	s.ds = ds
+	s.mu.Unlock()
+
+	if old != nil {
+		if err := old.Close(); err != nil {
+			s.log.Error("failed to close old dataset", zap.Error(err))
+		}
+	}
+}
+
+// cleanOldDatasets removes dataset files other than the one at keepPath.
+func (s *Service) cleanOldDatasets(keepPath string) {
+	entries, err := os.ReadDir(s.cfg.DataDir)
+	if err != nil {
+		return
+	}
+
+	for _, e := range entries {
+		if e.IsDir() {
+			continue
+		}
+		path := filepath.Join(s.cfg.DataDir, e.Name())
+		if path == keepPath {
+			continue
+		}
+		// Remove old datasets and temp files
+		if len(e.Name()) == 10 || strings.HasSuffix(e.Name(), ".downloading") {
+			if err := os.Remove(path); err != nil {
+				s.log.Warn("failed to remove old file", zap.String("path", path), zap.Error(err))
+			} else {
+				s.log.Info("removed old dataset", zap.String("path", path))
+			}
+		}
+	}
+}
+
+// Close releases all resources.
+func (s *Service) Close() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.ds != nil {
+		err := s.ds.Close()
+		s.ds = nil
+		return err
+	}
+	return nil
+}

internal/transport/middleware/log.go

@@ -0,0 +1,30 @@
+package middleware
+
+import (
+	"time"
+
+	"github.com/ogen-go/ogen/middleware"
+	"go.uber.org/zap"
+)
+
+// Logging returns an ogen middleware that logs request duration.
+func Logging(log *zap.Logger) middleware.Middleware {
+	return func(req middleware.Request, next func(req middleware.Request) (middleware.Response, error)) (middleware.Response, error) {
+		lg := log.With(zap.String("operation", req.OperationID))
+
+		start := time.Now()
+		resp, err := next(req)
+		dur := time.Since(start)
+
+		if err != nil {
+			lg.Error("request failed",
+				zap.Duration("duration", dur),
+				zap.Error(err))
+		} else {
+			lg.Info("request completed",
+				zap.Duration("duration", dur))
+		}
+
+		return resp, err
+	}
+}

internal/transport/rest/handler/deps.go

@@ -0,0 +1,16 @@
+package handler
+
+import (
+	"time"
+
+	"predictor-refactored/internal/dataset"
+	"predictor-refactored/internal/elevation"
+)
+
+// Service defines the interface the handler needs from the service layer.
+type Service interface {
+	Ready() bool
+	DatasetTime() (time.Time, bool)
+	Dataset() *dataset.File
+	Elevation() *elevation.Dataset
+}

internal/transport/rest/handler/handler.go

@@ -0,0 +1,216 @@
+package handler
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"predictor-refactored/internal/prediction"
+	api "predictor-refactored/pkg/rest"
+
+	"go.uber.org/zap"
+)
+
+var _ api.Handler = (*Handler)(nil)
+
+// Handler implements the ogen-generated api.Handler interface.
+type Handler struct {
+	svc Service
+	log *zap.Logger
+}
+
+// New creates a new Handler.
+func New(svc Service, log *zap.Logger) *Handler {
+	return &Handler{svc: svc, log: log}
+}
+
+// PerformPrediction implements the prediction endpoint.
+func (h *Handler) PerformPrediction(ctx context.Context, params api.PerformPredictionParams) (*api.PredictionResponse, error) {
+	if !h.svc.Ready() {
+		return nil, newError(http.StatusServiceUnavailable, "no dataset loaded, service is starting up")
+	}
+
+	ds := h.svc.Dataset()
+	if ds == nil {
+		return nil, newError(http.StatusServiceUnavailable, "dataset unavailable")
+	}
+
+	dsEpoch := float64(ds.DSTime.Unix())
+
+	// Parse parameters with defaults
+	profile := "standard_profile"
+	if p, ok := params.Profile.Get(); ok {
+		profile = string(p)
+	}
+
+	ascentRate := 5.0
+	if v, ok := params.AscentRate.Get(); ok {
+		ascentRate = v
+	}
+
+	burstAltitude := 28000.0
+	if v, ok := params.BurstAltitude.Get(); ok {
+		burstAltitude = v
+	}
+
+	descentRate := 5.0
+	if v, ok := params.DescentRate.Get(); ok {
+		descentRate = v
+	}
+
+	launchAlt := 0.0
+	if v, ok := params.LaunchAltitude.Get(); ok {
+		launchAlt = v
+	}
+
+	// Normalize longitude to [0, 360)
+	lng := params.LaunchLongitude
+	if lng < 0 {
+		lng += 360.0
+	}
+
+	launchTime := float64(params.LaunchDatetime.Unix())
+
+	warnings := &prediction.Warnings{}
+
+	// Build profile chain
+	elev := h.svc.Elevation()
+	var stages []prediction.Stage
+	switch profile {
+	case "standard_profile":
+		stages = prediction.StandardProfile(
+			ascentRate, burstAltitude, descentRate,
+			ds, dsEpoch, warnings, elev)
+	case "float_profile":
+		floatAlt := 25000.0
+		if v, ok := params.FloatAltitude.Get(); ok {
+			floatAlt = v
+		}
+		stopTime := params.LaunchDatetime.Add(24 * time.Hour)
+		if v, ok := params.StopDatetime.Get(); ok {
+			stopTime = v
+		}
+		stages = prediction.FloatProfile(
+			ascentRate, floatAlt, stopTime,
+			ds, dsEpoch, warnings)
+	default:
+		return nil, newError(http.StatusBadRequest, "unknown profile: "+profile)
+	}
+
+	// Run prediction
+	startTime := time.Now().UTC()
+	results := prediction.RunPrediction(launchTime, params.LaunchLatitude, lng, launchAlt, stages)
+	completeTime := time.Now().UTC()
+
+	// Build response
+	stageNames := []string{"ascent", "descent"}
+	if profile == "float_profile" {
+		stageNames = []string{"ascent", "float"}
+	}
+
+	var predItems []api.PredictionResponsePredictionItem
+	for i, sr := range results {
+		stageName := "ascent"
+		if i < len(stageNames) {
+			stageName = stageNames[i]
+		}
+
+		var stageEnum api.PredictionResponsePredictionItemStage
+		switch stageName {
+		case "ascent":
+			stageEnum = api.PredictionResponsePredictionItemStageAscent
+		case "descent":
+			stageEnum = api.PredictionResponsePredictionItemStageDescent
+		case "float":
+			stageEnum = api.PredictionResponsePredictionItemStageFloat
+		}
+
+		var traj []api.PredictionResponsePredictionItemTrajectoryItem
+		for _, pt := range sr.Points {
+			ptLng := pt.Lng
+			if ptLng > 180 {
+				ptLng -= 360
+			}
+			traj = append(traj, api.PredictionResponsePredictionItemTrajectoryItem{
+				Datetime:  time.Unix(int64(pt.T), 0).UTC(),
+				Latitude:  pt.Lat,
+				Longitude: ptLng,
+				Altitude:  pt.Alt,
+			})
+		}
+
+		predItems = append(predItems, api.PredictionResponsePredictionItem{
+			Stage:      stageEnum,
+			Trajectory: traj,
+		})
+	}
+
+	resp := &api.PredictionResponse{
+		Prediction: predItems,
+		Metadata: api.PredictionResponseMetadata{
+			StartDatetime:    startTime,
+			CompleteDatetime: completeTime,
+		},
+	}
+
+	// Echo request
+	resp.Request = api.NewOptPredictionResponseRequest(api.PredictionResponseRequest{
+		Dataset:         api.NewOptString(ds.DSTime.Format("2006-01-02T15:04:05Z")),
+		LaunchLatitude:  api.NewOptFloat64(params.LaunchLatitude),
+		LaunchLongitude: api.NewOptFloat64(params.LaunchLongitude),
+		LaunchDatetime:  api.NewOptString(params.LaunchDatetime.Format(time.RFC3339)),
+		LaunchAltitude:  params.LaunchAltitude,
+	})
+
+	// Warnings
+	warnMap := warnings.ToMap()
+	if len(warnMap) > 0 {
+		resp.Warnings = api.NewOptPredictionResponseWarnings(api.PredictionResponseWarnings{})
+	}
+
+	h.log.Info("prediction complete",
+		zap.String("profile", profile),
+		zap.Int("stages", len(results)),
+		zap.Duration("elapsed", completeTime.Sub(startTime)))
+
+	return resp, nil
+}
+
+// ReadinessCheck implements the health check endpoint.
+func (h *Handler) ReadinessCheck(ctx context.Context) (*api.ReadinessResponse, error) {
+	resp := &api.ReadinessResponse{}
+
+	if h.svc.Ready() {
+		resp.Status = api.ReadinessResponseStatusOk
+		if dsTime, ok := h.svc.DatasetTime(); ok {
+			resp.DatasetTime = api.NewOptDateTime(dsTime)
+		}
+	} else {
+		resp.Status = api.ReadinessResponseStatusNotReady
+		resp.ErrorMessage = api.NewOptString("no dataset loaded")
+	}
+
+	return resp, nil
+}
+
+// NewError creates an ErrorStatusCode from an error returned by a handler.
+func (h *Handler) NewError(ctx context.Context, err error) *api.ErrorStatusCode {
+	if statusErr, ok := err.(*api.ErrorStatusCode); ok {
+		return statusErr
+	}
+
+	h.log.Error("unhandled error", zap.Error(err))
+	return newError(http.StatusInternalServerError, err.Error())
+}
+
+func newError(status int, description string) *api.ErrorStatusCode {
+	return &api.ErrorStatusCode{
+		StatusCode: status,
+		Response: api.Error{
+			Error: api.ErrorError{
+				Type:        http.StatusText(status),
+				Description: description,
+			},
+		},
+	}
+}

internal/transport/rest/transport.go

@@ -0,0 +1,75 @@
+package rest
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+
+	"predictor-refactored/internal/transport/middleware"
+	"predictor-refactored/internal/transport/rest/handler"
+	api "predictor-refactored/pkg/rest"
+
+	"go.uber.org/zap"
+)
+
+// Transport wraps the ogen HTTP server.
+type Transport struct {
+	srv     *api.Server
+	handler *handler.Handler
+	port    int
+	log     *zap.Logger
+}
+
+// New creates a new REST transport.
+func New(h *handler.Handler, port int, log *zap.Logger) (*Transport, error) {
+	srv, err := api.NewServer(
+		h,
+		api.WithMiddleware(middleware.Logging(log)),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("create ogen server: %w", err)
+	}
+
+	return &Transport{
+		srv:     srv,
+		handler: h,
+		port:    port,
+		log:     log,
+	}, nil
+}
+
+// Run starts the HTTP server. Blocks until the server stops.
+func (t *Transport) Run() error {
+	mux := http.NewServeMux()
+	mux.Handle("/", t.srv)
+
+	httpSrv := &http.Server{
+		Addr:    fmt.Sprintf(":%d", t.port),
+		Handler: corsMiddleware(mux),
+	}
+
+	t.log.Info("starting HTTP server", zap.Int("port", t.port))
+	return httpSrv.ListenAndServe()
+}
+
+// Shutdown gracefully stops the HTTP server.
+func (t *Transport) Shutdown(ctx context.Context) error {
+	// The ogen server doesn't have a shutdown method;
+	// shutdown is handled by the http.Server in main.go
+	return nil
+}
+
+func corsMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Access-Control-Allow-Origin", "*")
+		w.Header().Set("Access-Control-Allow-Methods", "GET, OPTIONS")
+		w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
+
+		if r.Method == http.MethodOptions {
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+
+		next.ServeHTTP(w, r)
+	})
+}

pkg/rest/oas_cfg_gen.go

@@ -0,0 +1,318 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"net/http"
+	"strings"
+
+	ht "github.com/ogen-go/ogen/http"
+	"github.com/ogen-go/ogen/middleware"
+	"github.com/ogen-go/ogen/ogenerrors"
+	"github.com/ogen-go/ogen/otelogen"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/trace"
+)
+
+var (
+	// Allocate option closure once.
+	clientSpanKind = trace.WithSpanKind(trace.SpanKindClient)
+	// Allocate option closure once.
+	serverSpanKind = trace.WithSpanKind(trace.SpanKindServer)
+)
+
+type (
+	optionFunc[C any] func(*C)
+	otelOptionFunc    func(*otelConfig)
+)
+
+type otelConfig struct {
+	TracerProvider trace.TracerProvider
+	Tracer         trace.Tracer
+	MeterProvider  metric.MeterProvider
+	Meter          metric.Meter
+	Attributes     []attribute.KeyValue
+}
+
+func (cfg *otelConfig) initOTEL() {
+	if cfg.TracerProvider == nil {
+		cfg.TracerProvider = otel.GetTracerProvider()
+	}
+	if cfg.MeterProvider == nil {
+		cfg.MeterProvider = otel.GetMeterProvider()
+	}
+	cfg.Tracer = cfg.TracerProvider.Tracer(otelogen.Name,
+		trace.WithInstrumentationVersion(otelogen.SemVersion()),
+	)
+	cfg.Meter = cfg.MeterProvider.Meter(otelogen.Name,
+		metric.WithInstrumentationVersion(otelogen.SemVersion()),
+	)
+}
+
+// ErrorHandler is error handler.
+type ErrorHandler = ogenerrors.ErrorHandler
+
+type serverConfig struct {
+	otelConfig
+	NotFound           http.HandlerFunc
+	MethodNotAllowed   func(w http.ResponseWriter, r *http.Request, allowed string)
+	ErrorHandler       ErrorHandler
+	Prefix             string
+	Middleware         Middleware
+	MaxMultipartMemory int64
+}
+
+// ServerOption is server config option.
+type ServerOption interface {
+	applyServer(*serverConfig)
+}
+
+var _ ServerOption = (optionFunc[serverConfig])(nil)
+
+func (o optionFunc[C]) applyServer(c *C) {
+	o(c)
+}
+
+var _ ServerOption = (otelOptionFunc)(nil)
+
+func (o otelOptionFunc) applyServer(c *serverConfig) {
+	o(&c.otelConfig)
+}
+
+func newServerConfig(opts ...ServerOption) serverConfig {
+	cfg := serverConfig{
+		NotFound:           http.NotFound,
+		MethodNotAllowed:   nil,
+		ErrorHandler:       ogenerrors.DefaultErrorHandler,
+		Middleware:         nil,
+		MaxMultipartMemory: 32 << 20, // 32 MB
+	}
+	for _, opt := range opts {
+		opt.applyServer(&cfg)
+	}
+	cfg.initOTEL()
+	return cfg
+}
+
+type baseServer struct {
+	cfg      serverConfig
+	requests metric.Int64Counter
+	errors   metric.Int64Counter
+	duration metric.Float64Histogram
+}
+
+func (s baseServer) notFound(w http.ResponseWriter, r *http.Request) {
+	s.cfg.NotFound(w, r)
+}
+
+type notAllowedParams struct {
+	allowedMethods string
+	allowedHeaders map[string]string
+	acceptPost     string
+	acceptPatch    string
+}
+
+func (s baseServer) notAllowed(w http.ResponseWriter, r *http.Request, params notAllowedParams) {
+	h := w.Header()
+	isOptions := r.Method == "OPTIONS"
+	if isOptions {
+		h.Set("Access-Control-Allow-Methods", params.allowedMethods)
+		if params.allowedHeaders != nil {
+			m := r.Header.Get("Access-Control-Request-Method")
+			if m != "" {
+				allowedHeaders, ok := params.allowedHeaders[strings.ToUpper(m)]
+				if ok {
+					h.Set("Access-Control-Allow-Headers", allowedHeaders)
+				}
+			}
+		}
+		if params.acceptPost != "" {
+			h.Set("Accept-Post", params.acceptPost)
+		}
+		if params.acceptPatch != "" {
+			h.Set("Accept-Patch", params.acceptPatch)
+		}
+	}
+	if s.cfg.MethodNotAllowed != nil {
+		s.cfg.MethodNotAllowed(w, r, params.allowedMethods)
+		return
+	}
+	status := http.StatusNoContent
+	if !isOptions {
+		h.Set("Allow", params.allowedMethods)
+		status = http.StatusMethodNotAllowed
+	}
+	w.WriteHeader(status)
+}
+
+func (cfg serverConfig) baseServer() (s baseServer, err error) {
+	s = baseServer{cfg: cfg}
+	if s.requests, err = otelogen.ServerRequestCountCounter(s.cfg.Meter); err != nil {
+		return s, err
+	}
+	if s.errors, err = otelogen.ServerErrorsCountCounter(s.cfg.Meter); err != nil {
+		return s, err
+	}
+	if s.duration, err = otelogen.ServerDurationHistogram(s.cfg.Meter); err != nil {
+		return s, err
+	}
+	return s, nil
+}
+
+type clientConfig struct {
+	otelConfig
+	Client ht.Client
+}
+
+// ClientOption is client config option.
+type ClientOption interface {
+	applyClient(*clientConfig)
+}
+
+var _ ClientOption = (optionFunc[clientConfig])(nil)
+
+func (o optionFunc[C]) applyClient(c *C) {
+	o(c)
+}
+
+var _ ClientOption = (otelOptionFunc)(nil)
+
+func (o otelOptionFunc) applyClient(c *clientConfig) {
+	o(&c.otelConfig)
+}
+
+func newClientConfig(opts ...ClientOption) clientConfig {
+	cfg := clientConfig{
+		Client: http.DefaultClient,
+	}
+	for _, opt := range opts {
+		opt.applyClient(&cfg)
+	}
+	cfg.initOTEL()
+	return cfg
+}
+
+type baseClient struct {
+	cfg      clientConfig
+	requests metric.Int64Counter
+	errors   metric.Int64Counter
+	duration metric.Float64Histogram
+}
+
+func (cfg clientConfig) baseClient() (c baseClient, err error) {
+	c = baseClient{cfg: cfg}
+	if c.requests, err = otelogen.ClientRequestCountCounter(c.cfg.Meter); err != nil {
+		return c, err
+	}
+	if c.errors, err = otelogen.ClientErrorsCountCounter(c.cfg.Meter); err != nil {
+		return c, err
+	}
+	if c.duration, err = otelogen.ClientDurationHistogram(c.cfg.Meter); err != nil {
+		return c, err
+	}
+	return c, nil
+}
+
+// Option is config option.
+type Option interface {
+	ServerOption
+	ClientOption
+}
+
+// WithTracerProvider specifies a tracer provider to use for creating a tracer.
+//
+// If none is specified, the global provider is used.
+func WithTracerProvider(provider trace.TracerProvider) Option {
+	return otelOptionFunc(func(cfg *otelConfig) {
+		if provider != nil {
+			cfg.TracerProvider = provider
+		}
+	})
+}
+
+// WithMeterProvider specifies a meter provider to use for creating a meter.
+//
+// If none is specified, the otel.GetMeterProvider() is used.
+func WithMeterProvider(provider metric.MeterProvider) Option {
+	return otelOptionFunc(func(cfg *otelConfig) {
+		if provider != nil {
+			cfg.MeterProvider = provider
+		}
+	})
+}
+
+// WithAttributes specifies default otel attributes.
+func WithAttributes(attributes ...attribute.KeyValue) Option {
+	return otelOptionFunc(func(cfg *otelConfig) {
+		cfg.Attributes = attributes
+	})
+}
+
+// WithClient specifies http client to use.
+func WithClient(client ht.Client) ClientOption {
+	return optionFunc[clientConfig](func(cfg *clientConfig) {
+		if client != nil {
+			cfg.Client = client
+		}
+	})
+}
+
+// WithNotFound specifies Not Found handler to use.
+func WithNotFound(notFound http.HandlerFunc) ServerOption {
+	return optionFunc[serverConfig](func(cfg *serverConfig) {
+		if notFound != nil {
+			cfg.NotFound = notFound
+		}
+	})
+}
+
+// WithMethodNotAllowed specifies Method Not Allowed handler to use.
+func WithMethodNotAllowed(methodNotAllowed func(w http.ResponseWriter, r *http.Request, allowed string)) ServerOption {
+	return optionFunc[serverConfig](func(cfg *serverConfig) {
+		if methodNotAllowed != nil {
+			cfg.MethodNotAllowed = methodNotAllowed
+		}
+	})
+}
+
+// WithErrorHandler specifies error handler to use.
+func WithErrorHandler(h ErrorHandler) ServerOption {
+	return optionFunc[serverConfig](func(cfg *serverConfig) {
+		if h != nil {
+			cfg.ErrorHandler = h
+		}
+	})
+}
+
+// WithPathPrefix specifies server path prefix.
+func WithPathPrefix(prefix string) ServerOption {
+	return optionFunc[serverConfig](func(cfg *serverConfig) {
+		cfg.Prefix = prefix
+	})
+}
+
+// WithMiddleware specifies middlewares to use.
+func WithMiddleware(m ...Middleware) ServerOption {
+	return optionFunc[serverConfig](func(cfg *serverConfig) {
+		switch len(m) {
+		case 0:
+			cfg.Middleware = nil
+		case 1:
+			cfg.Middleware = m[0]
+		default:
+			cfg.Middleware = middleware.ChainMiddlewares(m...)
+		}
+	})
+}
+
+// WithMaxMultipartMemory specifies limit of memory for storing file parts.
+// File parts which can't be stored in memory will be stored on disk in temporary files.
+func WithMaxMultipartMemory(max int64) ServerOption {
+	return optionFunc[serverConfig](func(cfg *serverConfig) {
+		if max > 0 {
+			cfg.MaxMultipartMemory = max
+		}
+	})
+}

pkg/rest/oas_client_gen.go

@@ -0,0 +1,411 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"context"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/go-faster/errors"
+	"github.com/ogen-go/ogen/conv"
+	ht "github.com/ogen-go/ogen/http"
+	"github.com/ogen-go/ogen/otelogen"
+	"github.com/ogen-go/ogen/uri"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/metric"
+	semconv "go.opentelemetry.io/otel/semconv/v1.39.0"
+	"go.opentelemetry.io/otel/trace"
+)
+
+func trimTrailingSlashes(u *url.URL) {
+	u.Path = strings.TrimRight(u.Path, "/")
+	u.RawPath = strings.TrimRight(u.RawPath, "/")
+}
+
+// Invoker invokes operations described by OpenAPI v3 specification.
+type Invoker interface {
+	// PerformPrediction invokes performPrediction operation.
+	//
+	// Perform prediction.
+	//
+	// GET /api/v1/prediction
+	PerformPrediction(ctx context.Context, params PerformPredictionParams) (*PredictionResponse, error)
+	// ReadinessCheck invokes readinessCheck operation.
+	//
+	// Readiness check.
+	//
+	// GET /ready
+	ReadinessCheck(ctx context.Context) (*ReadinessResponse, error)
+}
+
+// Client implements OAS client.
+type Client struct {
+	serverURL *url.URL
+	baseClient
+}
+
+// NewClient initializes new Client defined by OAS.
+func NewClient(serverURL string, opts ...ClientOption) (*Client, error) {
+	u, err := url.Parse(serverURL)
+	if err != nil {
+		return nil, err
+	}
+	trimTrailingSlashes(u)
+
+	c, err := newClientConfig(opts...).baseClient()
+	if err != nil {
+		return nil, err
+	}
+	return &Client{
+		serverURL:  u,
+		baseClient: c,
+	}, nil
+}
+
+type serverURLKey struct{}
+
+// WithServerURL sets context key to override server URL.
+func WithServerURL(ctx context.Context, u *url.URL) context.Context {
+	return context.WithValue(ctx, serverURLKey{}, u)
+}
+
+func (c *Client) requestURL(ctx context.Context) *url.URL {
+	u, ok := ctx.Value(serverURLKey{}).(*url.URL)
+	if !ok {
+		return c.serverURL
+	}
+	return u
+}
+
+// PerformPrediction invokes performPrediction operation.
+//
+// Perform prediction.
+//
+// GET /api/v1/prediction
+func (c *Client) PerformPrediction(ctx context.Context, params PerformPredictionParams) (*PredictionResponse, error) {
+	res, err := c.sendPerformPrediction(ctx, params)
+	return res, err
+}
+
+func (c *Client) sendPerformPrediction(ctx context.Context, params PerformPredictionParams) (res *PredictionResponse, err error) {
+	otelAttrs := []attribute.KeyValue{
+		otelogen.OperationID("performPrediction"),
+		semconv.HTTPRequestMethodKey.String("GET"),
+		semconv.URLTemplateKey.String("/api/v1/prediction"),
+	}
+	otelAttrs = append(otelAttrs, c.cfg.Attributes...)
+
+	// Run stopwatch.
+	startTime := time.Now()
+	defer func() {
+		// Use floating point division here for higher precision (instead of Millisecond method).
+		elapsedDuration := time.Since(startTime)
+		c.duration.Record(ctx, float64(elapsedDuration)/float64(time.Millisecond), metric.WithAttributes(otelAttrs...))
+	}()
+
+	// Increment request counter.
+	c.requests.Add(ctx, 1, metric.WithAttributes(otelAttrs...))
+
+	// Start a span for this request.
+	ctx, span := c.cfg.Tracer.Start(ctx, PerformPredictionOperation,
+		trace.WithAttributes(otelAttrs...),
+		clientSpanKind,
+	)
+	// Track stage for error reporting.
+	var stage string
+	defer func() {
+		if err != nil {
+			span.RecordError(err)
+			span.SetStatus(codes.Error, stage)
+			c.errors.Add(ctx, 1, metric.WithAttributes(otelAttrs...))
+		}
+		span.End()
+	}()
+
+	stage = "BuildURL"
+	u := uri.Clone(c.requestURL(ctx))
+	var pathParts [1]string
+	pathParts[0] = "/api/v1/prediction"
+	uri.AddPathParts(u, pathParts[:]...)
+
+	stage = "EncodeQueryParams"
+	q := uri.NewQueryEncoder()
+	{
+		// Encode "launch_latitude" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "launch_latitude",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			return e.EncodeValue(conv.Float64ToString(params.LaunchLatitude))
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	{
+		// Encode "launch_longitude" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "launch_longitude",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			return e.EncodeValue(conv.Float64ToString(params.LaunchLongitude))
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	{
+		// Encode "launch_datetime" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "launch_datetime",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			return e.EncodeValue(conv.DateTimeToString(params.LaunchDatetime))
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	{
+		// Encode "launch_altitude" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "launch_altitude",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			if val, ok := params.LaunchAltitude.Get(); ok {
+				return e.EncodeValue(conv.Float64ToString(val))
+			}
+			return nil
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	{
+		// Encode "profile" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "profile",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			if val, ok := params.Profile.Get(); ok {
+				return e.EncodeValue(conv.StringToString(string(val)))
+			}
+			return nil
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	{
+		// Encode "ascent_rate" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "ascent_rate",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			if val, ok := params.AscentRate.Get(); ok {
+				return e.EncodeValue(conv.Float64ToString(val))
+			}
+			return nil
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	{
+		// Encode "burst_altitude" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "burst_altitude",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			if val, ok := params.BurstAltitude.Get(); ok {
+				return e.EncodeValue(conv.Float64ToString(val))
+			}
+			return nil
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	{
+		// Encode "descent_rate" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "descent_rate",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			if val, ok := params.DescentRate.Get(); ok {
+				return e.EncodeValue(conv.Float64ToString(val))
+			}
+			return nil
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	{
+		// Encode "float_altitude" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "float_altitude",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			if val, ok := params.FloatAltitude.Get(); ok {
+				return e.EncodeValue(conv.Float64ToString(val))
+			}
+			return nil
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	{
+		// Encode "stop_datetime" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "stop_datetime",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			if val, ok := params.StopDatetime.Get(); ok {
+				return e.EncodeValue(conv.DateTimeToString(val))
+			}
+			return nil
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	{
+		// Encode "dataset" parameter.
+		cfg := uri.QueryParameterEncodingConfig{
+			Name:    "dataset",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.EncodeParam(cfg, func(e uri.Encoder) error {
+			if val, ok := params.Dataset.Get(); ok {
+				return e.EncodeValue(conv.DateTimeToString(val))
+			}
+			return nil
+		}); err != nil {
+			return res, errors.Wrap(err, "encode query")
+		}
+	}
+	u.RawQuery = q.Values().Encode()
+
+	stage = "EncodeRequest"
+	r, err := ht.NewRequest(ctx, "GET", u)
+	if err != nil {
+		return res, errors.Wrap(err, "create request")
+	}
+
+	stage = "SendRequest"
+	resp, err := c.cfg.Client.Do(r)
+	if err != nil {
+		return res, errors.Wrap(err, "do request")
+	}
+	body := resp.Body
+	defer body.Close()
+
+	stage = "DecodeResponse"
+	result, err := decodePerformPredictionResponse(resp)
+	if err != nil {
+		return res, errors.Wrap(err, "decode response")
+	}
+
+	return result, nil
+}
+
+// ReadinessCheck invokes readinessCheck operation.
+//
+// Readiness check.
+//
+// GET /ready
+func (c *Client) ReadinessCheck(ctx context.Context) (*ReadinessResponse, error) {
+	res, err := c.sendReadinessCheck(ctx)
+	return res, err
+}
+
+func (c *Client) sendReadinessCheck(ctx context.Context) (res *ReadinessResponse, err error) {
+	otelAttrs := []attribute.KeyValue{
+		otelogen.OperationID("readinessCheck"),
+		semconv.HTTPRequestMethodKey.String("GET"),
+		semconv.URLTemplateKey.String("/ready"),
+	}
+	otelAttrs = append(otelAttrs, c.cfg.Attributes...)
+
+	// Run stopwatch.
+	startTime := time.Now()
+	defer func() {
+		// Use floating point division here for higher precision (instead of Millisecond method).
+		elapsedDuration := time.Since(startTime)
+		c.duration.Record(ctx, float64(elapsedDuration)/float64(time.Millisecond), metric.WithAttributes(otelAttrs...))
+	}()
+
+	// Increment request counter.
+	c.requests.Add(ctx, 1, metric.WithAttributes(otelAttrs...))
+
+	// Start a span for this request.
+	ctx, span := c.cfg.Tracer.Start(ctx, ReadinessCheckOperation,
+		trace.WithAttributes(otelAttrs...),
+		clientSpanKind,
+	)
+	// Track stage for error reporting.
+	var stage string
+	defer func() {
+		if err != nil {
+			span.RecordError(err)
+			span.SetStatus(codes.Error, stage)
+			c.errors.Add(ctx, 1, metric.WithAttributes(otelAttrs...))
+		}
+		span.End()
+	}()
+
+	stage = "BuildURL"
+	u := uri.Clone(c.requestURL(ctx))
+	var pathParts [1]string
+	pathParts[0] = "/ready"
+	uri.AddPathParts(u, pathParts[:]...)
+
+	stage = "EncodeRequest"
+	r, err := ht.NewRequest(ctx, "GET", u)
+	if err != nil {
+		return res, errors.Wrap(err, "create request")
+	}
+
+	stage = "SendRequest"
+	resp, err := c.cfg.Client.Do(r)
+	if err != nil {
+		return res, errors.Wrap(err, "do request")
+	}
+	body := resp.Body
+	defer body.Close()
+
+	stage = "DecodeResponse"
+	result, err := decodeReadinessCheckResponse(resp)
+	if err != nil {
+		return res, errors.Wrap(err, "decode response")
+	}
+
+	return result, nil
+}

pkg/rest/oas_handlers_gen.go

@@ -0,0 +1,363 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"github.com/go-faster/errors"
+	ht "github.com/ogen-go/ogen/http"
+	"github.com/ogen-go/ogen/middleware"
+	"github.com/ogen-go/ogen/ogenerrors"
+	"github.com/ogen-go/ogen/otelogen"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/metric"
+	semconv "go.opentelemetry.io/otel/semconv/v1.39.0"
+	"go.opentelemetry.io/otel/trace"
+)
+
+type codeRecorder struct {
+	http.ResponseWriter
+	status int
+}
+
+func (c *codeRecorder) WriteHeader(status int) {
+	c.status = status
+	c.ResponseWriter.WriteHeader(status)
+}
+
+func (c *codeRecorder) Unwrap() http.ResponseWriter {
+	return c.ResponseWriter
+}
+
+// handlePerformPredictionRequest handles performPrediction operation.
+//
+// Perform prediction.
+//
+// GET /api/v1/prediction
+func (s *Server) handlePerformPredictionRequest(args [0]string, argsEscaped bool, w http.ResponseWriter, r *http.Request) {
+	statusWriter := &codeRecorder{ResponseWriter: w}
+	w = statusWriter
+	otelAttrs := []attribute.KeyValue{
+		otelogen.OperationID("performPrediction"),
+		semconv.HTTPRequestMethodKey.String("GET"),
+		semconv.HTTPRouteKey.String("/api/v1/prediction"),
+	}
+	// Add attributes from config.
+	otelAttrs = append(otelAttrs, s.cfg.Attributes...)
+
+	// Start a span for this request.
+	ctx, span := s.cfg.Tracer.Start(r.Context(), PerformPredictionOperation,
+		trace.WithAttributes(otelAttrs...),
+		serverSpanKind,
+	)
+	defer span.End()
+
+	// Add Labeler to context.
+	labeler := &Labeler{attrs: otelAttrs}
+	ctx = contextWithLabeler(ctx, labeler)
+
+	// Run stopwatch.
+	startTime := time.Now()
+	defer func() {
+		elapsedDuration := time.Since(startTime)
+
+		attrSet := labeler.AttributeSet()
+		attrs := attrSet.ToSlice()
+		code := statusWriter.status
+		if code != 0 {
+			codeAttr := semconv.HTTPResponseStatusCode(code)
+			attrs = append(attrs, codeAttr)
+			span.SetAttributes(codeAttr)
+		}
+		attrOpt := metric.WithAttributes(attrs...)
+
+		// Increment request counter.
+		s.requests.Add(ctx, 1, attrOpt)
+
+		// Use floating point division here for higher precision (instead of Millisecond method).
+		s.duration.Record(ctx, float64(elapsedDuration)/float64(time.Millisecond), attrOpt)
+	}()
+
+	var (
+		recordError = func(stage string, err error) {
+			span.RecordError(err)
+
+			// https://opentelemetry.io/docs/specs/semconv/http/http-spans/#status
+			// Span Status MUST be left unset if HTTP status code was in the 1xx, 2xx or 3xx ranges,
+			// unless there was another error (e.g., network error receiving the response body; or 3xx codes with
+			// max redirects exceeded), in which case status MUST be set to Error.
+			code := statusWriter.status
+			if code < 100 || code >= 500 {
+				span.SetStatus(codes.Error, stage)
+			}
+
+			attrSet := labeler.AttributeSet()
+			attrs := attrSet.ToSlice()
+			if code != 0 {
+				attrs = append(attrs, semconv.HTTPResponseStatusCode(code))
+			}
+
+			s.errors.Add(ctx, 1, metric.WithAttributes(attrs...))
+		}
+		err          error
+		opErrContext = ogenerrors.OperationContext{
+			Name: PerformPredictionOperation,
+			ID:   "performPrediction",
+		}
+	)
+	params, err := decodePerformPredictionParams(args, argsEscaped, r)
+	if err != nil {
+		err = &ogenerrors.DecodeParamsError{
+			OperationContext: opErrContext,
+			Err:              err,
+		}
+		defer recordError("DecodeParams", err)
+		s.cfg.ErrorHandler(ctx, w, r, err)
+		return
+	}
+
+	var rawBody []byte
+
+	var response *PredictionResponse
+	if m := s.cfg.Middleware; m != nil {
+		mreq := middleware.Request{
+			Context:          ctx,
+			OperationName:    PerformPredictionOperation,
+			OperationSummary: "Perform prediction",
+			OperationID:      "performPrediction",
+			Body:             nil,
+			RawBody:          rawBody,
+			Params: middleware.Parameters{
+				{
+					Name: "launch_latitude",
+					In:   "query",
+				}: params.LaunchLatitude,
+				{
+					Name: "launch_longitude",
+					In:   "query",
+				}: params.LaunchLongitude,
+				{
+					Name: "launch_datetime",
+					In:   "query",
+				}: params.LaunchDatetime,
+				{
+					Name: "launch_altitude",
+					In:   "query",
+				}: params.LaunchAltitude,
+				{
+					Name: "profile",
+					In:   "query",
+				}: params.Profile,
+				{
+					Name: "ascent_rate",
+					In:   "query",
+				}: params.AscentRate,
+				{
+					Name: "burst_altitude",
+					In:   "query",
+				}: params.BurstAltitude,
+				{
+					Name: "descent_rate",
+					In:   "query",
+				}: params.DescentRate,
+				{
+					Name: "float_altitude",
+					In:   "query",
+				}: params.FloatAltitude,
+				{
+					Name: "stop_datetime",
+					In:   "query",
+				}: params.StopDatetime,
+				{
+					Name: "dataset",
+					In:   "query",
+				}: params.Dataset,
+			},
+			Raw: r,
+		}
+
+		type (
+			Request  = struct{}
+			Params   = PerformPredictionParams
+			Response = *PredictionResponse
+		)
+		response, err = middleware.HookMiddleware[
+			Request,
+			Params,
+			Response,
+		](
+			m,
+			mreq,
+			unpackPerformPredictionParams,
+			func(ctx context.Context, request Request, params Params) (response Response, err error) {
+				response, err = s.h.PerformPrediction(ctx, params)
+				return response, err
+			},
+		)
+	} else {
+		response, err = s.h.PerformPrediction(ctx, params)
+	}
+	if err != nil {
+		if errRes, ok := errors.Into[*ErrorStatusCode](err); ok {
+			if err := encodeErrorResponse(errRes, w, span); err != nil {
+				defer recordError("Internal", err)
+			}
+			return
+		}
+		if errors.Is(err, ht.ErrNotImplemented) {
+			s.cfg.ErrorHandler(ctx, w, r, err)
+			return
+		}
+		if err := encodeErrorResponse(s.h.NewError(ctx, err), w, span); err != nil {
+			defer recordError("Internal", err)
+		}
+		return
+	}
+
+	if err := encodePerformPredictionResponse(response, w, span); err != nil {
+		defer recordError("EncodeResponse", err)
+		if !errors.Is(err, ht.ErrInternalServerErrorResponse) {
+			s.cfg.ErrorHandler(ctx, w, r, err)
+		}
+		return
+	}
+}
+
+// handleReadinessCheckRequest handles readinessCheck operation.
+//
+// Readiness check.
+//
+// GET /ready
+func (s *Server) handleReadinessCheckRequest(args [0]string, argsEscaped bool, w http.ResponseWriter, r *http.Request) {
+	statusWriter := &codeRecorder{ResponseWriter: w}
+	w = statusWriter
+	otelAttrs := []attribute.KeyValue{
+		otelogen.OperationID("readinessCheck"),
+		semconv.HTTPRequestMethodKey.String("GET"),
+		semconv.HTTPRouteKey.String("/ready"),
+	}
+	// Add attributes from config.
+	otelAttrs = append(otelAttrs, s.cfg.Attributes...)
+
+	// Start a span for this request.
+	ctx, span := s.cfg.Tracer.Start(r.Context(), ReadinessCheckOperation,
+		trace.WithAttributes(otelAttrs...),
+		serverSpanKind,
+	)
+	defer span.End()
+
+	// Add Labeler to context.
+	labeler := &Labeler{attrs: otelAttrs}
+	ctx = contextWithLabeler(ctx, labeler)
+
+	// Run stopwatch.
+	startTime := time.Now()
+	defer func() {
+		elapsedDuration := time.Since(startTime)
+
+		attrSet := labeler.AttributeSet()
+		attrs := attrSet.ToSlice()
+		code := statusWriter.status
+		if code != 0 {
+			codeAttr := semconv.HTTPResponseStatusCode(code)
+			attrs = append(attrs, codeAttr)
+			span.SetAttributes(codeAttr)
+		}
+		attrOpt := metric.WithAttributes(attrs...)
+
+		// Increment request counter.
+		s.requests.Add(ctx, 1, attrOpt)
+
+		// Use floating point division here for higher precision (instead of Millisecond method).
+		s.duration.Record(ctx, float64(elapsedDuration)/float64(time.Millisecond), attrOpt)
+	}()
+
+	var (
+		recordError = func(stage string, err error) {
+			span.RecordError(err)
+
+			// https://opentelemetry.io/docs/specs/semconv/http/http-spans/#status
+			// Span Status MUST be left unset if HTTP status code was in the 1xx, 2xx or 3xx ranges,
+			// unless there was another error (e.g., network error receiving the response body; or 3xx codes with
+			// max redirects exceeded), in which case status MUST be set to Error.
+			code := statusWriter.status
+			if code < 100 || code >= 500 {
+				span.SetStatus(codes.Error, stage)
+			}
+
+			attrSet := labeler.AttributeSet()
+			attrs := attrSet.ToSlice()
+			if code != 0 {
+				attrs = append(attrs, semconv.HTTPResponseStatusCode(code))
+			}
+
+			s.errors.Add(ctx, 1, metric.WithAttributes(attrs...))
+		}
+		err error
+	)
+
+	var rawBody []byte
+
+	var response *ReadinessResponse
+	if m := s.cfg.Middleware; m != nil {
+		mreq := middleware.Request{
+			Context:          ctx,
+			OperationName:    ReadinessCheckOperation,
+			OperationSummary: "Readiness check",
+			OperationID:      "readinessCheck",
+			Body:             nil,
+			RawBody:          rawBody,
+			Params:           middleware.Parameters{},
+			Raw:              r,
+		}
+
+		type (
+			Request  = struct{}
+			Params   = struct{}
+			Response = *ReadinessResponse
+		)
+		response, err = middleware.HookMiddleware[
+			Request,
+			Params,
+			Response,
+		](
+			m,
+			mreq,
+			nil,
+			func(ctx context.Context, request Request, params Params) (response Response, err error) {
+				response, err = s.h.ReadinessCheck(ctx)
+				return response, err
+			},
+		)
+	} else {
+		response, err = s.h.ReadinessCheck(ctx)
+	}
+	if err != nil {
+		if errRes, ok := errors.Into[*ErrorStatusCode](err); ok {
+			if err := encodeErrorResponse(errRes, w, span); err != nil {
+				defer recordError("Internal", err)
+			}
+			return
+		}
+		if errors.Is(err, ht.ErrNotImplemented) {
+			s.cfg.ErrorHandler(ctx, w, r, err)
+			return
+		}
+		if err := encodeErrorResponse(s.h.NewError(ctx, err), w, span); err != nil {
+			defer recordError("Internal", err)
+		}
+		return
+	}
+
+	if err := encodeReadinessCheckResponse(response, w, span); err != nil {
+		defer recordError("EncodeResponse", err)
+		if !errors.Is(err, ht.ErrInternalServerErrorResponse) {
+			s.cfg.ErrorHandler(ctx, w, r, err)
+		}
+		return
+	}
+}

pkg/rest/oas_labeler_gen.go

@@ -0,0 +1,42 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// Labeler is used to allow adding custom attributes to the server request metrics.
+type Labeler struct {
+	attrs []attribute.KeyValue
+}
+
+// Add attributes to the Labeler.
+func (l *Labeler) Add(attrs ...attribute.KeyValue) {
+	l.attrs = append(l.attrs, attrs...)
+}
+
+// AttributeSet returns the attributes added to the Labeler as an attribute.Set.
+func (l *Labeler) AttributeSet() attribute.Set {
+	return attribute.NewSet(l.attrs...)
+}
+
+type labelerContextKey struct{}
+
+// LabelerFromContext retrieves the Labeler from the provided context, if present.
+//
+// If no Labeler was found in the provided context a new, empty Labeler is returned and the second
+// return value is false. In this case it is safe to use the Labeler but any attributes added to
+// it will not be used.
+func LabelerFromContext(ctx context.Context) (*Labeler, bool) {
+	if l, ok := ctx.Value(labelerContextKey{}).(*Labeler); ok {
+		return l, true
+	}
+	return &Labeler{}, false
+}
+
+func contextWithLabeler(ctx context.Context, l *Labeler) context.Context {
+	return context.WithValue(ctx, labelerContextKey{}, l)
+}

pkg/rest/oas_middleware_gen.go

@@ -0,0 +1,10 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"github.com/ogen-go/ogen/middleware"
+)
+
+// Middleware is middleware type.
+type Middleware = middleware.Middleware

pkg/rest/oas_operations_gen.go

@@ -0,0 +1,11 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+// OperationName is the ogen operation name
+type OperationName = string
+
+const (
+	PerformPredictionOperation OperationName = "PerformPrediction"
+	ReadinessCheckOperation    OperationName = "ReadinessCheck"
+)

pkg/rest/oas_parameters_gen.go

@@ -0,0 +1,679 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/go-faster/errors"
+	"github.com/ogen-go/ogen/conv"
+	"github.com/ogen-go/ogen/middleware"
+	"github.com/ogen-go/ogen/ogenerrors"
+	"github.com/ogen-go/ogen/uri"
+	"github.com/ogen-go/ogen/validate"
+)
+
+// PerformPredictionParams is parameters of performPrediction operation.
+type PerformPredictionParams struct {
+	LaunchLatitude  float64
+	LaunchLongitude float64
+	LaunchDatetime  time.Time
+	LaunchAltitude  OptFloat64                  `json:",omitempty,omitzero"`
+	Profile         OptPerformPredictionProfile `json:",omitempty,omitzero"`
+	AscentRate      OptFloat64                  `json:",omitempty,omitzero"`
+	BurstAltitude   OptFloat64                  `json:",omitempty,omitzero"`
+	DescentRate     OptFloat64                  `json:",omitempty,omitzero"`
+	FloatAltitude   OptFloat64                  `json:",omitempty,omitzero"`
+	StopDatetime    OptDateTime                 `json:",omitempty,omitzero"`
+	Dataset         OptDateTime                 `json:",omitempty,omitzero"`
+}
+
+func unpackPerformPredictionParams(packed middleware.Parameters) (params PerformPredictionParams) {
+	{
+		key := middleware.ParameterKey{
+			Name: "launch_latitude",
+			In:   "query",
+		}
+		params.LaunchLatitude = packed[key].(float64)
+	}
+	{
+		key := middleware.ParameterKey{
+			Name: "launch_longitude",
+			In:   "query",
+		}
+		params.LaunchLongitude = packed[key].(float64)
+	}
+	{
+		key := middleware.ParameterKey{
+			Name: "launch_datetime",
+			In:   "query",
+		}
+		params.LaunchDatetime = packed[key].(time.Time)
+	}
+	{
+		key := middleware.ParameterKey{
+			Name: "launch_altitude",
+			In:   "query",
+		}
+		if v, ok := packed[key]; ok {
+			params.LaunchAltitude = v.(OptFloat64)
+		}
+	}
+	{
+		key := middleware.ParameterKey{
+			Name: "profile",
+			In:   "query",
+		}
+		if v, ok := packed[key]; ok {
+			params.Profile = v.(OptPerformPredictionProfile)
+		}
+	}
+	{
+		key := middleware.ParameterKey{
+			Name: "ascent_rate",
+			In:   "query",
+		}
+		if v, ok := packed[key]; ok {
+			params.AscentRate = v.(OptFloat64)
+		}
+	}
+	{
+		key := middleware.ParameterKey{
+			Name: "burst_altitude",
+			In:   "query",
+		}
+		if v, ok := packed[key]; ok {
+			params.BurstAltitude = v.(OptFloat64)
+		}
+	}
+	{
+		key := middleware.ParameterKey{
+			Name: "descent_rate",
+			In:   "query",
+		}
+		if v, ok := packed[key]; ok {
+			params.DescentRate = v.(OptFloat64)
+		}
+	}
+	{
+		key := middleware.ParameterKey{
+			Name: "float_altitude",
+			In:   "query",
+		}
+		if v, ok := packed[key]; ok {
+			params.FloatAltitude = v.(OptFloat64)
+		}
+	}
+	{
+		key := middleware.ParameterKey{
+			Name: "stop_datetime",
+			In:   "query",
+		}
+		if v, ok := packed[key]; ok {
+			params.StopDatetime = v.(OptDateTime)
+		}
+	}
+	{
+		key := middleware.ParameterKey{
+			Name: "dataset",
+			In:   "query",
+		}
+		if v, ok := packed[key]; ok {
+			params.Dataset = v.(OptDateTime)
+		}
+	}
+	return params
+}
+
+func decodePerformPredictionParams(args [0]string, argsEscaped bool, r *http.Request) (params PerformPredictionParams, _ error) {
+	q := uri.NewQueryDecoder(r.URL.Query())
+	// Decode query: launch_latitude.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "launch_latitude",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				val, err := d.DecodeValue()
+				if err != nil {
+					return err
+				}
+
+				c, err := conv.ToFloat64(val)
+				if err != nil {
+					return err
+				}
+
+				params.LaunchLatitude = c
+				return nil
+			}); err != nil {
+				return err
+			}
+			if err := func() error {
+				if err := (validate.Float{}).Validate(float64(params.LaunchLatitude)); err != nil {
+					return errors.Wrap(err, "float")
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		} else {
+			return err
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "launch_latitude",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	// Decode query: launch_longitude.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "launch_longitude",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				val, err := d.DecodeValue()
+				if err != nil {
+					return err
+				}
+
+				c, err := conv.ToFloat64(val)
+				if err != nil {
+					return err
+				}
+
+				params.LaunchLongitude = c
+				return nil
+			}); err != nil {
+				return err
+			}
+			if err := func() error {
+				if err := (validate.Float{}).Validate(float64(params.LaunchLongitude)); err != nil {
+					return errors.Wrap(err, "float")
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		} else {
+			return err
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "launch_longitude",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	// Decode query: launch_datetime.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "launch_datetime",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				val, err := d.DecodeValue()
+				if err != nil {
+					return err
+				}
+
+				c, err := conv.ToDateTime(val)
+				if err != nil {
+					return err
+				}
+
+				params.LaunchDatetime = c
+				return nil
+			}); err != nil {
+				return err
+			}
+		} else {
+			return err
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "launch_datetime",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	// Decode query: launch_altitude.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "launch_altitude",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				var paramsDotLaunchAltitudeVal float64
+				if err := func() error {
+					val, err := d.DecodeValue()
+					if err != nil {
+						return err
+					}
+
+					c, err := conv.ToFloat64(val)
+					if err != nil {
+						return err
+					}
+
+					paramsDotLaunchAltitudeVal = c
+					return nil
+				}(); err != nil {
+					return err
+				}
+				params.LaunchAltitude.SetTo(paramsDotLaunchAltitudeVal)
+				return nil
+			}); err != nil {
+				return err
+			}
+			if err := func() error {
+				if value, ok := params.LaunchAltitude.Get(); ok {
+					if err := func() error {
+						if err := (validate.Float{}).Validate(float64(value)); err != nil {
+							return errors.Wrap(err, "float")
+						}
+						return nil
+					}(); err != nil {
+						return err
+					}
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "launch_altitude",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	// Set default value for query: profile.
+	{
+		val := PerformPredictionProfile("standard_profile")
+		params.Profile.SetTo(val)
+	}
+	// Decode query: profile.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "profile",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				var paramsDotProfileVal PerformPredictionProfile
+				if err := func() error {
+					val, err := d.DecodeValue()
+					if err != nil {
+						return err
+					}
+
+					c, err := conv.ToString(val)
+					if err != nil {
+						return err
+					}
+
+					paramsDotProfileVal = PerformPredictionProfile(c)
+					return nil
+				}(); err != nil {
+					return err
+				}
+				params.Profile.SetTo(paramsDotProfileVal)
+				return nil
+			}); err != nil {
+				return err
+			}
+			if err := func() error {
+				if value, ok := params.Profile.Get(); ok {
+					if err := func() error {
+						if err := value.Validate(); err != nil {
+							return err
+						}
+						return nil
+					}(); err != nil {
+						return err
+					}
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "profile",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	// Decode query: ascent_rate.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "ascent_rate",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				var paramsDotAscentRateVal float64
+				if err := func() error {
+					val, err := d.DecodeValue()
+					if err != nil {
+						return err
+					}
+
+					c, err := conv.ToFloat64(val)
+					if err != nil {
+						return err
+					}
+
+					paramsDotAscentRateVal = c
+					return nil
+				}(); err != nil {
+					return err
+				}
+				params.AscentRate.SetTo(paramsDotAscentRateVal)
+				return nil
+			}); err != nil {
+				return err
+			}
+			if err := func() error {
+				if value, ok := params.AscentRate.Get(); ok {
+					if err := func() error {
+						if err := (validate.Float{}).Validate(float64(value)); err != nil {
+							return errors.Wrap(err, "float")
+						}
+						return nil
+					}(); err != nil {
+						return err
+					}
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "ascent_rate",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	// Decode query: burst_altitude.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "burst_altitude",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				var paramsDotBurstAltitudeVal float64
+				if err := func() error {
+					val, err := d.DecodeValue()
+					if err != nil {
+						return err
+					}
+
+					c, err := conv.ToFloat64(val)
+					if err != nil {
+						return err
+					}
+
+					paramsDotBurstAltitudeVal = c
+					return nil
+				}(); err != nil {
+					return err
+				}
+				params.BurstAltitude.SetTo(paramsDotBurstAltitudeVal)
+				return nil
+			}); err != nil {
+				return err
+			}
+			if err := func() error {
+				if value, ok := params.BurstAltitude.Get(); ok {
+					if err := func() error {
+						if err := (validate.Float{}).Validate(float64(value)); err != nil {
+							return errors.Wrap(err, "float")
+						}
+						return nil
+					}(); err != nil {
+						return err
+					}
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "burst_altitude",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	// Decode query: descent_rate.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "descent_rate",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				var paramsDotDescentRateVal float64
+				if err := func() error {
+					val, err := d.DecodeValue()
+					if err != nil {
+						return err
+					}
+
+					c, err := conv.ToFloat64(val)
+					if err != nil {
+						return err
+					}
+
+					paramsDotDescentRateVal = c
+					return nil
+				}(); err != nil {
+					return err
+				}
+				params.DescentRate.SetTo(paramsDotDescentRateVal)
+				return nil
+			}); err != nil {
+				return err
+			}
+			if err := func() error {
+				if value, ok := params.DescentRate.Get(); ok {
+					if err := func() error {
+						if err := (validate.Float{}).Validate(float64(value)); err != nil {
+							return errors.Wrap(err, "float")
+						}
+						return nil
+					}(); err != nil {
+						return err
+					}
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "descent_rate",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	// Decode query: float_altitude.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "float_altitude",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				var paramsDotFloatAltitudeVal float64
+				if err := func() error {
+					val, err := d.DecodeValue()
+					if err != nil {
+						return err
+					}
+
+					c, err := conv.ToFloat64(val)
+					if err != nil {
+						return err
+					}
+
+					paramsDotFloatAltitudeVal = c
+					return nil
+				}(); err != nil {
+					return err
+				}
+				params.FloatAltitude.SetTo(paramsDotFloatAltitudeVal)
+				return nil
+			}); err != nil {
+				return err
+			}
+			if err := func() error {
+				if value, ok := params.FloatAltitude.Get(); ok {
+					if err := func() error {
+						if err := (validate.Float{}).Validate(float64(value)); err != nil {
+							return errors.Wrap(err, "float")
+						}
+						return nil
+					}(); err != nil {
+						return err
+					}
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "float_altitude",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	// Decode query: stop_datetime.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "stop_datetime",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				var paramsDotStopDatetimeVal time.Time
+				if err := func() error {
+					val, err := d.DecodeValue()
+					if err != nil {
+						return err
+					}
+
+					c, err := conv.ToDateTime(val)
+					if err != nil {
+						return err
+					}
+
+					paramsDotStopDatetimeVal = c
+					return nil
+				}(); err != nil {
+					return err
+				}
+				params.StopDatetime.SetTo(paramsDotStopDatetimeVal)
+				return nil
+			}); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "stop_datetime",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	// Decode query: dataset.
+	if err := func() error {
+		cfg := uri.QueryParameterDecodingConfig{
+			Name:    "dataset",
+			Style:   uri.QueryStyleForm,
+			Explode: true,
+		}
+
+		if err := q.HasParam(cfg); err == nil {
+			if err := q.DecodeParam(cfg, func(d uri.Decoder) error {
+				var paramsDotDatasetVal time.Time
+				if err := func() error {
+					val, err := d.DecodeValue()
+					if err != nil {
+						return err
+					}
+
+					c, err := conv.ToDateTime(val)
+					if err != nil {
+						return err
+					}
+
+					paramsDotDatasetVal = c
+					return nil
+				}(); err != nil {
+					return err
+				}
+				params.Dataset.SetTo(paramsDotDatasetVal)
+				return nil
+			}); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		return params, &ogenerrors.DecodeParamError{
+			Name: "dataset",
+			In:   "query",
+			Err:  err,
+		}
+	}
+	return params, nil
+}

pkg/rest/oas_request_decoders_gen.go

@@ -0,0 +1,3 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest

pkg/rest/oas_request_encoders_gen.go

@@ -0,0 +1,3 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest

pkg/rest/oas_response_decoders_gen.go

@@ -0,0 +1,198 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"io"
+	"mime"
+	"net/http"
+
+	"github.com/go-faster/errors"
+	"github.com/go-faster/jx"
+	"github.com/ogen-go/ogen/ogenerrors"
+	"github.com/ogen-go/ogen/validate"
+)
+
+func decodePerformPredictionResponse(resp *http.Response) (res *PredictionResponse, _ error) {
+	switch resp.StatusCode {
+	case 200:
+		// Code 200.
+		ct, _, err := mime.ParseMediaType(resp.Header.Get("Content-Type"))
+		if err != nil {
+			return res, errors.Wrap(err, "parse media type")
+		}
+		switch {
+		case ct == "application/json":
+			buf, err := io.ReadAll(resp.Body)
+			if err != nil {
+				return res, err
+			}
+			d := jx.DecodeBytes(buf)
+
+			var response PredictionResponse
+			if err := func() error {
+				if err := response.Decode(d); err != nil {
+					return err
+				}
+				if err := d.Skip(); err != io.EOF {
+					return errors.New("unexpected trailing data")
+				}
+				return nil
+			}(); err != nil {
+				err = &ogenerrors.DecodeBodyError{
+					ContentType: ct,
+					Body:        buf,
+					Err:         err,
+				}
+				return res, err
+			}
+			// Validate response.
+			if err := func() error {
+				if err := response.Validate(); err != nil {
+					return err
+				}
+				return nil
+			}(); err != nil {
+				return res, errors.Wrap(err, "validate")
+			}
+			return &response, nil
+		default:
+			return res, validate.InvalidContentType(ct)
+		}
+	}
+	// Convenient error response.
+	defRes, err := func() (res *ErrorStatusCode, err error) {
+		ct, _, err := mime.ParseMediaType(resp.Header.Get("Content-Type"))
+		if err != nil {
+			return res, errors.Wrap(err, "parse media type")
+		}
+		switch {
+		case ct == "application/json":
+			buf, err := io.ReadAll(resp.Body)
+			if err != nil {
+				return res, err
+			}
+			d := jx.DecodeBytes(buf)
+
+			var response Error
+			if err := func() error {
+				if err := response.Decode(d); err != nil {
+					return err
+				}
+				if err := d.Skip(); err != io.EOF {
+					return errors.New("unexpected trailing data")
+				}
+				return nil
+			}(); err != nil {
+				err = &ogenerrors.DecodeBodyError{
+					ContentType: ct,
+					Body:        buf,
+					Err:         err,
+				}
+				return res, err
+			}
+			return &ErrorStatusCode{
+				StatusCode: resp.StatusCode,
+				Response:   response,
+			}, nil
+		default:
+			return res, validate.InvalidContentType(ct)
+		}
+	}()
+	if err != nil {
+		return res, errors.Wrapf(err, "default (code %d)", resp.StatusCode)
+	}
+	return res, errors.Wrap(defRes, "error")
+}
+
+func decodeReadinessCheckResponse(resp *http.Response) (res *ReadinessResponse, _ error) {
+	switch resp.StatusCode {
+	case 200:
+		// Code 200.
+		ct, _, err := mime.ParseMediaType(resp.Header.Get("Content-Type"))
+		if err != nil {
+			return res, errors.Wrap(err, "parse media type")
+		}
+		switch {
+		case ct == "application/json":
+			buf, err := io.ReadAll(resp.Body)
+			if err != nil {
+				return res, err
+			}
+			d := jx.DecodeBytes(buf)
+
+			var response ReadinessResponse
+			if err := func() error {
+				if err := response.Decode(d); err != nil {
+					return err
+				}
+				if err := d.Skip(); err != io.EOF {
+					return errors.New("unexpected trailing data")
+				}
+				return nil
+			}(); err != nil {
+				err = &ogenerrors.DecodeBodyError{
+					ContentType: ct,
+					Body:        buf,
+					Err:         err,
+				}
+				return res, err
+			}
+			// Validate response.
+			if err := func() error {
+				if err := response.Validate(); err != nil {
+					return err
+				}
+				return nil
+			}(); err != nil {
+				return res, errors.Wrap(err, "validate")
+			}
+			return &response, nil
+		default:
+			return res, validate.InvalidContentType(ct)
+		}
+	}
+	// Convenient error response.
+	defRes, err := func() (res *ErrorStatusCode, err error) {
+		ct, _, err := mime.ParseMediaType(resp.Header.Get("Content-Type"))
+		if err != nil {
+			return res, errors.Wrap(err, "parse media type")
+		}
+		switch {
+		case ct == "application/json":
+			buf, err := io.ReadAll(resp.Body)
+			if err != nil {
+				return res, err
+			}
+			d := jx.DecodeBytes(buf)
+
+			var response Error
+			if err := func() error {
+				if err := response.Decode(d); err != nil {
+					return err
+				}
+				if err := d.Skip(); err != io.EOF {
+					return errors.New("unexpected trailing data")
+				}
+				return nil
+			}(); err != nil {
+				err = &ogenerrors.DecodeBodyError{
+					ContentType: ct,
+					Body:        buf,
+					Err:         err,
+				}
+				return res, err
+			}
+			return &ErrorStatusCode{
+				StatusCode: resp.StatusCode,
+				Response:   response,
+			}, nil
+		default:
+			return res, validate.InvalidContentType(ct)
+		}
+	}()
+	if err != nil {
+		return res, errors.Wrapf(err, "default (code %d)", resp.StatusCode)
+	}
+	return res, errors.Wrap(defRes, "error")
+}

pkg/rest/oas_response_encoders_gen.go

@@ -0,0 +1,68 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"net/http"
+
+	"github.com/go-faster/errors"
+	"github.com/go-faster/jx"
+	ht "github.com/ogen-go/ogen/http"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/trace"
+)
+
+func encodePerformPredictionResponse(response *PredictionResponse, w http.ResponseWriter, span trace.Span) error {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(200)
+	span.SetStatus(codes.Ok, http.StatusText(200))
+
+	e := new(jx.Encoder)
+	response.Encode(e)
+	if _, err := e.WriteTo(w); err != nil {
+		return errors.Wrap(err, "write")
+	}
+
+	return nil
+}
+
+func encodeReadinessCheckResponse(response *ReadinessResponse, w http.ResponseWriter, span trace.Span) error {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(200)
+	span.SetStatus(codes.Ok, http.StatusText(200))
+
+	e := new(jx.Encoder)
+	response.Encode(e)
+	if _, err := e.WriteTo(w); err != nil {
+		return errors.Wrap(err, "write")
+	}
+
+	return nil
+}
+
+func encodeErrorResponse(response *ErrorStatusCode, w http.ResponseWriter, span trace.Span) error {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	code := response.StatusCode
+	if code == 0 {
+		// Set default status code.
+		code = http.StatusOK
+	}
+	w.WriteHeader(code)
+	if st := http.StatusText(code); code >= http.StatusBadRequest {
+		span.SetStatus(codes.Error, st)
+	} else {
+		span.SetStatus(codes.Ok, st)
+	}
+
+	e := new(jx.Encoder)
+	response.Response.Encode(e)
+	if _, err := e.WriteTo(w); err != nil {
+		return errors.Wrap(err, "write")
+	}
+
+	if code >= http.StatusInternalServerError {
+		return errors.Wrapf(ht.ErrInternalServerErrorResponse, "code: %d, message: %s", code, http.StatusText(code))
+	}
+	return nil
+
+}

pkg/rest/oas_router_gen.go

@@ -0,0 +1,268 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/ogen-go/ogen/uri"
+)
+
+func (s *Server) cutPrefix(path string) (string, bool) {
+	prefix := s.cfg.Prefix
+	if prefix == "" {
+		return path, true
+	}
+	if !strings.HasPrefix(path, prefix) {
+		// Prefix doesn't match.
+		return "", false
+	}
+	// Cut prefix from the path.
+	return strings.TrimPrefix(path, prefix), true
+}
+
+// ServeHTTP serves http request as defined by OpenAPI v3 specification,
+// calling handler that matches the path or returning not found error.
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	elem := r.URL.Path
+	elemIsEscaped := false
+	if rawPath := r.URL.RawPath; rawPath != "" {
+		if normalized, ok := uri.NormalizeEscapedPath(rawPath); ok {
+			elem = normalized
+			elemIsEscaped = strings.ContainsRune(elem, '%')
+		}
+	}
+
+	elem, ok := s.cutPrefix(elem)
+	if !ok || len(elem) == 0 {
+		s.notFound(w, r)
+		return
+	}
+
+	// Static code generated router with unwrapped path search.
+	switch {
+	default:
+		if len(elem) == 0 {
+			break
+		}
+		switch elem[0] {
+		case '/': // Prefix: "/"
+
+			if l := len("/"); len(elem) >= l && elem[0:l] == "/" {
+				elem = elem[l:]
+			} else {
+				break
+			}
+
+			if len(elem) == 0 {
+				break
+			}
+			switch elem[0] {
+			case 'a': // Prefix: "api/v1/prediction"
+
+				if l := len("api/v1/prediction"); len(elem) >= l && elem[0:l] == "api/v1/prediction" {
+					elem = elem[l:]
+				} else {
+					break
+				}
+
+				if len(elem) == 0 {
+					// Leaf node.
+					switch r.Method {
+					case "GET":
+						s.handlePerformPredictionRequest([0]string{}, elemIsEscaped, w, r)
+					default:
+						s.notAllowed(w, r, notAllowedParams{
+							allowedMethods: "GET",
+							allowedHeaders: nil,
+							acceptPost:     "",
+							acceptPatch:    "",
+						})
+					}
+
+					return
+				}
+
+			case 'r': // Prefix: "ready"
+
+				if l := len("ready"); len(elem) >= l && elem[0:l] == "ready" {
+					elem = elem[l:]
+				} else {
+					break
+				}
+
+				if len(elem) == 0 {
+					// Leaf node.
+					switch r.Method {
+					case "GET":
+						s.handleReadinessCheckRequest([0]string{}, elemIsEscaped, w, r)
+					default:
+						s.notAllowed(w, r, notAllowedParams{
+							allowedMethods: "GET",
+							allowedHeaders: nil,
+							acceptPost:     "",
+							acceptPatch:    "",
+						})
+					}
+
+					return
+				}
+
+			}
+
+		}
+	}
+	s.notFound(w, r)
+}
+
+// Route is route object.
+type Route struct {
+	name           string
+	summary        string
+	operationID    string
+	operationGroup string
+	pathPattern    string
+	count          int
+	args           [0]string
+}
+
+// Name returns ogen operation name.
+//
+// It is guaranteed to be unique and not empty.
+func (r Route) Name() string {
+	return r.name
+}
+
+// Summary returns OpenAPI summary.
+func (r Route) Summary() string {
+	return r.summary
+}
+
+// OperationID returns OpenAPI operationId.
+func (r Route) OperationID() string {
+	return r.operationID
+}
+
+// OperationGroup returns the x-ogen-operation-group value.
+func (r Route) OperationGroup() string {
+	return r.operationGroup
+}
+
+// PathPattern returns OpenAPI path.
+func (r Route) PathPattern() string {
+	return r.pathPattern
+}
+
+// Args returns parsed arguments.
+func (r Route) Args() []string {
+	return r.args[:r.count]
+}
+
+// FindRoute finds Route for given method and path.
+//
+// Note: this method does not unescape path or handle reserved characters in path properly. Use FindPath instead.
+func (s *Server) FindRoute(method, path string) (Route, bool) {
+	return s.FindPath(method, &url.URL{Path: path})
+}
+
+// FindPath finds Route for given method and URL.
+func (s *Server) FindPath(method string, u *url.URL) (r Route, _ bool) {
+	var (
+		elem = u.Path
+		args = r.args
+	)
+	if rawPath := u.RawPath; rawPath != "" {
+		if normalized, ok := uri.NormalizeEscapedPath(rawPath); ok {
+			elem = normalized
+		}
+		defer func() {
+			for i, arg := range r.args[:r.count] {
+				if unescaped, err := url.PathUnescape(arg); err == nil {
+					r.args[i] = unescaped
+				}
+			}
+		}()
+	}
+
+	elem, ok := s.cutPrefix(elem)
+	if !ok {
+		return r, false
+	}
+
+	// Static code generated router with unwrapped path search.
+	switch {
+	default:
+		if len(elem) == 0 {
+			break
+		}
+		switch elem[0] {
+		case '/': // Prefix: "/"
+
+			if l := len("/"); len(elem) >= l && elem[0:l] == "/" {
+				elem = elem[l:]
+			} else {
+				break
+			}
+
+			if len(elem) == 0 {
+				break
+			}
+			switch elem[0] {
+			case 'a': // Prefix: "api/v1/prediction"
+
+				if l := len("api/v1/prediction"); len(elem) >= l && elem[0:l] == "api/v1/prediction" {
+					elem = elem[l:]
+				} else {
+					break
+				}
+
+				if len(elem) == 0 {
+					// Leaf node.
+					switch method {
+					case "GET":
+						r.name = PerformPredictionOperation
+						r.summary = "Perform prediction"
+						r.operationID = "performPrediction"
+						r.operationGroup = ""
+						r.pathPattern = "/api/v1/prediction"
+						r.args = args
+						r.count = 0
+						return r, true
+					default:
+						return
+					}
+				}
+
+			case 'r': // Prefix: "ready"
+
+				if l := len("ready"); len(elem) >= l && elem[0:l] == "ready" {
+					elem = elem[l:]
+				} else {
+					break
+				}
+
+				if len(elem) == 0 {
+					// Leaf node.
+					switch method {
+					case "GET":
+						r.name = ReadinessCheckOperation
+						r.summary = "Readiness check"
+						r.operationID = "readinessCheck"
+						r.operationGroup = ""
+						r.pathPattern = "/ready"
+						r.args = args
+						r.count = 0
+						return r, true
+					default:
+						return
+					}
+				}
+
+			}
+
+		}
+	}
+	return r, false
+}

pkg/rest/oas_schemas_gen.go

@@ -0,0 +1,789 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/go-faster/errors"
+	"github.com/go-faster/jx"
+)
+
+func (s *ErrorStatusCode) Error() string {
+	return fmt.Sprintf("code %d: %+v", s.StatusCode, s.Response)
+}
+
+// Ref: #/components/schemas/Error
+type Error struct {
+	Error ErrorError `json:"error"`
+}
+
+// GetError returns the value of Error.
+func (s *Error) GetError() ErrorError {
+	return s.Error
+}
+
+// SetError sets the value of Error.
+func (s *Error) SetError(val ErrorError) {
+	s.Error = val
+}
+
+type ErrorError struct {
+	Type        string `json:"type"`
+	Description string `json:"description"`
+}
+
+// GetType returns the value of Type.
+func (s *ErrorError) GetType() string {
+	return s.Type
+}
+
+// GetDescription returns the value of Description.
+func (s *ErrorError) GetDescription() string {
+	return s.Description
+}
+
+// SetType sets the value of Type.
+func (s *ErrorError) SetType(val string) {
+	s.Type = val
+}
+
+// SetDescription sets the value of Description.
+func (s *ErrorError) SetDescription(val string) {
+	s.Description = val
+}
+
+// ErrorStatusCode wraps Error with StatusCode.
+type ErrorStatusCode struct {
+	StatusCode int
+	Response   Error
+}
+
+// GetStatusCode returns the value of StatusCode.
+func (s *ErrorStatusCode) GetStatusCode() int {
+	return s.StatusCode
+}
+
+// GetResponse returns the value of Response.
+func (s *ErrorStatusCode) GetResponse() Error {
+	return s.Response
+}
+
+// SetStatusCode sets the value of StatusCode.
+func (s *ErrorStatusCode) SetStatusCode(val int) {
+	s.StatusCode = val
+}
+
+// SetResponse sets the value of Response.
+func (s *ErrorStatusCode) SetResponse(val Error) {
+	s.Response = val
+}
+
+// NewOptDateTime returns new OptDateTime with value set to v.
+func NewOptDateTime(v time.Time) OptDateTime {
+	return OptDateTime{
+		Value: v,
+		Set:   true,
+	}
+}
+
+// OptDateTime is optional time.Time.
+type OptDateTime struct {
+	Value time.Time
+	Set   bool
+}
+
+// IsSet returns true if OptDateTime was set.
+func (o OptDateTime) IsSet() bool { return o.Set }
+
+// Reset unsets value.
+func (o *OptDateTime) Reset() {
+	var v time.Time
+	o.Value = v
+	o.Set = false
+}
+
+// SetTo sets value to v.
+func (o *OptDateTime) SetTo(v time.Time) {
+	o.Set = true
+	o.Value = v
+}
+
+// Get returns value and boolean that denotes whether value was set.
+func (o OptDateTime) Get() (v time.Time, ok bool) {
+	if !o.Set {
+		return v, false
+	}
+	return o.Value, true
+}
+
+// Or returns value if set, or given parameter if does not.
+func (o OptDateTime) Or(d time.Time) time.Time {
+	if v, ok := o.Get(); ok {
+		return v
+	}
+	return d
+}
+
+// NewOptFloat64 returns new OptFloat64 with value set to v.
+func NewOptFloat64(v float64) OptFloat64 {
+	return OptFloat64{
+		Value: v,
+		Set:   true,
+	}
+}
+
+// OptFloat64 is optional float64.
+type OptFloat64 struct {
+	Value float64
+	Set   bool
+}
+
+// IsSet returns true if OptFloat64 was set.
+func (o OptFloat64) IsSet() bool { return o.Set }
+
+// Reset unsets value.
+func (o *OptFloat64) Reset() {
+	var v float64
+	o.Value = v
+	o.Set = false
+}
+
+// SetTo sets value to v.
+func (o *OptFloat64) SetTo(v float64) {
+	o.Set = true
+	o.Value = v
+}
+
+// Get returns value and boolean that denotes whether value was set.
+func (o OptFloat64) Get() (v float64, ok bool) {
+	if !o.Set {
+		return v, false
+	}
+	return o.Value, true
+}
+
+// Or returns value if set, or given parameter if does not.
+func (o OptFloat64) Or(d float64) float64 {
+	if v, ok := o.Get(); ok {
+		return v
+	}
+	return d
+}
+
+// NewOptPerformPredictionProfile returns new OptPerformPredictionProfile with value set to v.
+func NewOptPerformPredictionProfile(v PerformPredictionProfile) OptPerformPredictionProfile {
+	return OptPerformPredictionProfile{
+		Value: v,
+		Set:   true,
+	}
+}
+
+// OptPerformPredictionProfile is optional PerformPredictionProfile.
+type OptPerformPredictionProfile struct {
+	Value PerformPredictionProfile
+	Set   bool
+}
+
+// IsSet returns true if OptPerformPredictionProfile was set.
+func (o OptPerformPredictionProfile) IsSet() bool { return o.Set }
+
+// Reset unsets value.
+func (o *OptPerformPredictionProfile) Reset() {
+	var v PerformPredictionProfile
+	o.Value = v
+	o.Set = false
+}
+
+// SetTo sets value to v.
+func (o *OptPerformPredictionProfile) SetTo(v PerformPredictionProfile) {
+	o.Set = true
+	o.Value = v
+}
+
+// Get returns value and boolean that denotes whether value was set.
+func (o OptPerformPredictionProfile) Get() (v PerformPredictionProfile, ok bool) {
+	if !o.Set {
+		return v, false
+	}
+	return o.Value, true
+}
+
+// Or returns value if set, or given parameter if does not.
+func (o OptPerformPredictionProfile) Or(d PerformPredictionProfile) PerformPredictionProfile {
+	if v, ok := o.Get(); ok {
+		return v
+	}
+	return d
+}
+
+// NewOptPredictionResponseRequest returns new OptPredictionResponseRequest with value set to v.
+func NewOptPredictionResponseRequest(v PredictionResponseRequest) OptPredictionResponseRequest {
+	return OptPredictionResponseRequest{
+		Value: v,
+		Set:   true,
+	}
+}
+
+// OptPredictionResponseRequest is optional PredictionResponseRequest.
+type OptPredictionResponseRequest struct {
+	Value PredictionResponseRequest
+	Set   bool
+}
+
+// IsSet returns true if OptPredictionResponseRequest was set.
+func (o OptPredictionResponseRequest) IsSet() bool { return o.Set }
+
+// Reset unsets value.
+func (o *OptPredictionResponseRequest) Reset() {
+	var v PredictionResponseRequest
+	o.Value = v
+	o.Set = false
+}
+
+// SetTo sets value to v.
+func (o *OptPredictionResponseRequest) SetTo(v PredictionResponseRequest) {
+	o.Set = true
+	o.Value = v
+}
+
+// Get returns value and boolean that denotes whether value was set.
+func (o OptPredictionResponseRequest) Get() (v PredictionResponseRequest, ok bool) {
+	if !o.Set {
+		return v, false
+	}
+	return o.Value, true
+}
+
+// Or returns value if set, or given parameter if does not.
+func (o OptPredictionResponseRequest) Or(d PredictionResponseRequest) PredictionResponseRequest {
+	if v, ok := o.Get(); ok {
+		return v
+	}
+	return d
+}
+
+// NewOptPredictionResponseWarnings returns new OptPredictionResponseWarnings with value set to v.
+func NewOptPredictionResponseWarnings(v PredictionResponseWarnings) OptPredictionResponseWarnings {
+	return OptPredictionResponseWarnings{
+		Value: v,
+		Set:   true,
+	}
+}
+
+// OptPredictionResponseWarnings is optional PredictionResponseWarnings.
+type OptPredictionResponseWarnings struct {
+	Value PredictionResponseWarnings
+	Set   bool
+}
+
+// IsSet returns true if OptPredictionResponseWarnings was set.
+func (o OptPredictionResponseWarnings) IsSet() bool { return o.Set }
+
+// Reset unsets value.
+func (o *OptPredictionResponseWarnings) Reset() {
+	var v PredictionResponseWarnings
+	o.Value = v
+	o.Set = false
+}
+
+// SetTo sets value to v.
+func (o *OptPredictionResponseWarnings) SetTo(v PredictionResponseWarnings) {
+	o.Set = true
+	o.Value = v
+}
+
+// Get returns value and boolean that denotes whether value was set.
+func (o OptPredictionResponseWarnings) Get() (v PredictionResponseWarnings, ok bool) {
+	if !o.Set {
+		return v, false
+	}
+	return o.Value, true
+}
+
+// Or returns value if set, or given parameter if does not.
+func (o OptPredictionResponseWarnings) Or(d PredictionResponseWarnings) PredictionResponseWarnings {
+	if v, ok := o.Get(); ok {
+		return v
+	}
+	return d
+}
+
+// NewOptString returns new OptString with value set to v.
+func NewOptString(v string) OptString {
+	return OptString{
+		Value: v,
+		Set:   true,
+	}
+}
+
+// OptString is optional string.
+type OptString struct {
+	Value string
+	Set   bool
+}
+
+// IsSet returns true if OptString was set.
+func (o OptString) IsSet() bool { return o.Set }
+
+// Reset unsets value.
+func (o *OptString) Reset() {
+	var v string
+	o.Value = v
+	o.Set = false
+}
+
+// SetTo sets value to v.
+func (o *OptString) SetTo(v string) {
+	o.Set = true
+	o.Value = v
+}
+
+// Get returns value and boolean that denotes whether value was set.
+func (o OptString) Get() (v string, ok bool) {
+	if !o.Set {
+		return v, false
+	}
+	return o.Value, true
+}
+
+// Or returns value if set, or given parameter if does not.
+func (o OptString) Or(d string) string {
+	if v, ok := o.Get(); ok {
+		return v
+	}
+	return d
+}
+
+type PerformPredictionProfile string
+
+const (
+	PerformPredictionProfileStandardProfile PerformPredictionProfile = "standard_profile"
+	PerformPredictionProfileFloatProfile    PerformPredictionProfile = "float_profile"
+)
+
+// AllValues returns all PerformPredictionProfile values.
+func (PerformPredictionProfile) AllValues() []PerformPredictionProfile {
+	return []PerformPredictionProfile{
+		PerformPredictionProfileStandardProfile,
+		PerformPredictionProfileFloatProfile,
+	}
+}
+
+// MarshalText implements encoding.TextMarshaler.
+func (s PerformPredictionProfile) MarshalText() ([]byte, error) {
+	switch s {
+	case PerformPredictionProfileStandardProfile:
+		return []byte(s), nil
+	case PerformPredictionProfileFloatProfile:
+		return []byte(s), nil
+	default:
+		return nil, errors.Errorf("invalid value: %q", s)
+	}
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler.
+func (s *PerformPredictionProfile) UnmarshalText(data []byte) error {
+	switch PerformPredictionProfile(data) {
+	case PerformPredictionProfileStandardProfile:
+		*s = PerformPredictionProfileStandardProfile
+		return nil
+	case PerformPredictionProfileFloatProfile:
+		*s = PerformPredictionProfileFloatProfile
+		return nil
+	default:
+		return errors.Errorf("invalid value: %q", data)
+	}
+}
+
+// Ref: #/components/schemas/PredictionResponse
+type PredictionResponse struct {
+	Request    OptPredictionResponseRequest       `json:"request"`
+	Prediction []PredictionResponsePredictionItem `json:"prediction"`
+	Metadata   PredictionResponseMetadata         `json:"metadata"`
+	Warnings   OptPredictionResponseWarnings      `json:"warnings"`
+}
+
+// GetRequest returns the value of Request.
+func (s *PredictionResponse) GetRequest() OptPredictionResponseRequest {
+	return s.Request
+}
+
+// GetPrediction returns the value of Prediction.
+func (s *PredictionResponse) GetPrediction() []PredictionResponsePredictionItem {
+	return s.Prediction
+}
+
+// GetMetadata returns the value of Metadata.
+func (s *PredictionResponse) GetMetadata() PredictionResponseMetadata {
+	return s.Metadata
+}
+
+// GetWarnings returns the value of Warnings.
+func (s *PredictionResponse) GetWarnings() OptPredictionResponseWarnings {
+	return s.Warnings
+}
+
+// SetRequest sets the value of Request.
+func (s *PredictionResponse) SetRequest(val OptPredictionResponseRequest) {
+	s.Request = val
+}
+
+// SetPrediction sets the value of Prediction.
+func (s *PredictionResponse) SetPrediction(val []PredictionResponsePredictionItem) {
+	s.Prediction = val
+}
+
+// SetMetadata sets the value of Metadata.
+func (s *PredictionResponse) SetMetadata(val PredictionResponseMetadata) {
+	s.Metadata = val
+}
+
+// SetWarnings sets the value of Warnings.
+func (s *PredictionResponse) SetWarnings(val OptPredictionResponseWarnings) {
+	s.Warnings = val
+}
+
+type PredictionResponseMetadata struct {
+	StartDatetime    time.Time `json:"start_datetime"`
+	CompleteDatetime time.Time `json:"complete_datetime"`
+}
+
+// GetStartDatetime returns the value of StartDatetime.
+func (s *PredictionResponseMetadata) GetStartDatetime() time.Time {
+	return s.StartDatetime
+}
+
+// GetCompleteDatetime returns the value of CompleteDatetime.
+func (s *PredictionResponseMetadata) GetCompleteDatetime() time.Time {
+	return s.CompleteDatetime
+}
+
+// SetStartDatetime sets the value of StartDatetime.
+func (s *PredictionResponseMetadata) SetStartDatetime(val time.Time) {
+	s.StartDatetime = val
+}
+
+// SetCompleteDatetime sets the value of CompleteDatetime.
+func (s *PredictionResponseMetadata) SetCompleteDatetime(val time.Time) {
+	s.CompleteDatetime = val
+}
+
+type PredictionResponsePredictionItem struct {
+	Stage      PredictionResponsePredictionItemStage            `json:"stage"`
+	Trajectory []PredictionResponsePredictionItemTrajectoryItem `json:"trajectory"`
+}
+
+// GetStage returns the value of Stage.
+func (s *PredictionResponsePredictionItem) GetStage() PredictionResponsePredictionItemStage {
+	return s.Stage
+}
+
+// GetTrajectory returns the value of Trajectory.
+func (s *PredictionResponsePredictionItem) GetTrajectory() []PredictionResponsePredictionItemTrajectoryItem {
+	return s.Trajectory
+}
+
+// SetStage sets the value of Stage.
+func (s *PredictionResponsePredictionItem) SetStage(val PredictionResponsePredictionItemStage) {
+	s.Stage = val
+}
+
+// SetTrajectory sets the value of Trajectory.
+func (s *PredictionResponsePredictionItem) SetTrajectory(val []PredictionResponsePredictionItemTrajectoryItem) {
+	s.Trajectory = val
+}
+
+type PredictionResponsePredictionItemStage string
+
+const (
+	PredictionResponsePredictionItemStageAscent  PredictionResponsePredictionItemStage = "ascent"
+	PredictionResponsePredictionItemStageDescent PredictionResponsePredictionItemStage = "descent"
+	PredictionResponsePredictionItemStageFloat   PredictionResponsePredictionItemStage = "float"
+)
+
+// AllValues returns all PredictionResponsePredictionItemStage values.
+func (PredictionResponsePredictionItemStage) AllValues() []PredictionResponsePredictionItemStage {
+	return []PredictionResponsePredictionItemStage{
+		PredictionResponsePredictionItemStageAscent,
+		PredictionResponsePredictionItemStageDescent,
+		PredictionResponsePredictionItemStageFloat,
+	}
+}
+
+// MarshalText implements encoding.TextMarshaler.
+func (s PredictionResponsePredictionItemStage) MarshalText() ([]byte, error) {
+	switch s {
+	case PredictionResponsePredictionItemStageAscent:
+		return []byte(s), nil
+	case PredictionResponsePredictionItemStageDescent:
+		return []byte(s), nil
+	case PredictionResponsePredictionItemStageFloat:
+		return []byte(s), nil
+	default:
+		return nil, errors.Errorf("invalid value: %q", s)
+	}
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler.
+func (s *PredictionResponsePredictionItemStage) UnmarshalText(data []byte) error {
+	switch PredictionResponsePredictionItemStage(data) {
+	case PredictionResponsePredictionItemStageAscent:
+		*s = PredictionResponsePredictionItemStageAscent
+		return nil
+	case PredictionResponsePredictionItemStageDescent:
+		*s = PredictionResponsePredictionItemStageDescent
+		return nil
+	case PredictionResponsePredictionItemStageFloat:
+		*s = PredictionResponsePredictionItemStageFloat
+		return nil
+	default:
+		return errors.Errorf("invalid value: %q", data)
+	}
+}
+
+type PredictionResponsePredictionItemTrajectoryItem struct {
+	Datetime  time.Time `json:"datetime"`
+	Latitude  float64   `json:"latitude"`
+	Longitude float64   `json:"longitude"`
+	Altitude  float64   `json:"altitude"`
+}
+
+// GetDatetime returns the value of Datetime.
+func (s *PredictionResponsePredictionItemTrajectoryItem) GetDatetime() time.Time {
+	return s.Datetime
+}
+
+// GetLatitude returns the value of Latitude.
+func (s *PredictionResponsePredictionItemTrajectoryItem) GetLatitude() float64 {
+	return s.Latitude
+}
+
+// GetLongitude returns the value of Longitude.
+func (s *PredictionResponsePredictionItemTrajectoryItem) GetLongitude() float64 {
+	return s.Longitude
+}
+
+// GetAltitude returns the value of Altitude.
+func (s *PredictionResponsePredictionItemTrajectoryItem) GetAltitude() float64 {
+	return s.Altitude
+}
+
+// SetDatetime sets the value of Datetime.
+func (s *PredictionResponsePredictionItemTrajectoryItem) SetDatetime(val time.Time) {
+	s.Datetime = val
+}
+
+// SetLatitude sets the value of Latitude.
+func (s *PredictionResponsePredictionItemTrajectoryItem) SetLatitude(val float64) {
+	s.Latitude = val
+}
+
+// SetLongitude sets the value of Longitude.
+func (s *PredictionResponsePredictionItemTrajectoryItem) SetLongitude(val float64) {
+	s.Longitude = val
+}
+
+// SetAltitude sets the value of Altitude.
+func (s *PredictionResponsePredictionItemTrajectoryItem) SetAltitude(val float64) {
+	s.Altitude = val
+}
+
+type PredictionResponseRequest struct {
+	Dataset         OptString  `json:"dataset"`
+	LaunchLatitude  OptFloat64 `json:"launch_latitude"`
+	LaunchLongitude OptFloat64 `json:"launch_longitude"`
+	LaunchDatetime  OptString  `json:"launch_datetime"`
+	LaunchAltitude  OptFloat64 `json:"launch_altitude"`
+	Profile         OptString  `json:"profile"`
+	AscentRate      OptFloat64 `json:"ascent_rate"`
+	BurstAltitude   OptFloat64 `json:"burst_altitude"`
+	DescentRate     OptFloat64 `json:"descent_rate"`
+}
+
+// GetDataset returns the value of Dataset.
+func (s *PredictionResponseRequest) GetDataset() OptString {
+	return s.Dataset
+}
+
+// GetLaunchLatitude returns the value of LaunchLatitude.
+func (s *PredictionResponseRequest) GetLaunchLatitude() OptFloat64 {
+	return s.LaunchLatitude
+}
+
+// GetLaunchLongitude returns the value of LaunchLongitude.
+func (s *PredictionResponseRequest) GetLaunchLongitude() OptFloat64 {
+	return s.LaunchLongitude
+}
+
+// GetLaunchDatetime returns the value of LaunchDatetime.
+func (s *PredictionResponseRequest) GetLaunchDatetime() OptString {
+	return s.LaunchDatetime
+}
+
+// GetLaunchAltitude returns the value of LaunchAltitude.
+func (s *PredictionResponseRequest) GetLaunchAltitude() OptFloat64 {
+	return s.LaunchAltitude
+}
+
+// GetProfile returns the value of Profile.
+func (s *PredictionResponseRequest) GetProfile() OptString {
+	return s.Profile
+}
+
+// GetAscentRate returns the value of AscentRate.
+func (s *PredictionResponseRequest) GetAscentRate() OptFloat64 {
+	return s.AscentRate
+}
+
+// GetBurstAltitude returns the value of BurstAltitude.
+func (s *PredictionResponseRequest) GetBurstAltitude() OptFloat64 {
+	return s.BurstAltitude
+}
+
+// GetDescentRate returns the value of DescentRate.
+func (s *PredictionResponseRequest) GetDescentRate() OptFloat64 {
+	return s.DescentRate
+}
+
+// SetDataset sets the value of Dataset.
+func (s *PredictionResponseRequest) SetDataset(val OptString) {
+	s.Dataset = val
+}
+
+// SetLaunchLatitude sets the value of LaunchLatitude.
+func (s *PredictionResponseRequest) SetLaunchLatitude(val OptFloat64) {
+	s.LaunchLatitude = val
+}
+
+// SetLaunchLongitude sets the value of LaunchLongitude.
+func (s *PredictionResponseRequest) SetLaunchLongitude(val OptFloat64) {
+	s.LaunchLongitude = val
+}
+
+// SetLaunchDatetime sets the value of LaunchDatetime.
+func (s *PredictionResponseRequest) SetLaunchDatetime(val OptString) {
+	s.LaunchDatetime = val
+}
+
+// SetLaunchAltitude sets the value of LaunchAltitude.
+func (s *PredictionResponseRequest) SetLaunchAltitude(val OptFloat64) {
+	s.LaunchAltitude = val
+}
+
+// SetProfile sets the value of Profile.
+func (s *PredictionResponseRequest) SetProfile(val OptString) {
+	s.Profile = val
+}
+
+// SetAscentRate sets the value of AscentRate.
+func (s *PredictionResponseRequest) SetAscentRate(val OptFloat64) {
+	s.AscentRate = val
+}
+
+// SetBurstAltitude sets the value of BurstAltitude.
+func (s *PredictionResponseRequest) SetBurstAltitude(val OptFloat64) {
+	s.BurstAltitude = val
+}
+
+// SetDescentRate sets the value of DescentRate.
+func (s *PredictionResponseRequest) SetDescentRate(val OptFloat64) {
+	s.DescentRate = val
+}
+
+type PredictionResponseWarnings map[string]jx.Raw
+
+func (s *PredictionResponseWarnings) init() PredictionResponseWarnings {
+	m := *s
+	if m == nil {
+		m = map[string]jx.Raw{}
+		*s = m
+	}
+	return m
+}
+
+// Ref: #/components/schemas/ReadinessResponse
+type ReadinessResponse struct {
+	Status       ReadinessResponseStatus `json:"status"`
+	DatasetTime  OptDateTime             `json:"dataset_time"`
+	ErrorMessage OptString               `json:"error_message"`
+}
+
+// GetStatus returns the value of Status.
+func (s *ReadinessResponse) GetStatus() ReadinessResponseStatus {
+	return s.Status
+}
+
+// GetDatasetTime returns the value of DatasetTime.
+func (s *ReadinessResponse) GetDatasetTime() OptDateTime {
+	return s.DatasetTime
+}
+
+// GetErrorMessage returns the value of ErrorMessage.
+func (s *ReadinessResponse) GetErrorMessage() OptString {
+	return s.ErrorMessage
+}
+
+// SetStatus sets the value of Status.
+func (s *ReadinessResponse) SetStatus(val ReadinessResponseStatus) {
+	s.Status = val
+}
+
+// SetDatasetTime sets the value of DatasetTime.
+func (s *ReadinessResponse) SetDatasetTime(val OptDateTime) {
+	s.DatasetTime = val
+}
+
+// SetErrorMessage sets the value of ErrorMessage.
+func (s *ReadinessResponse) SetErrorMessage(val OptString) {
+	s.ErrorMessage = val
+}
+
+type ReadinessResponseStatus string
+
+const (
+	ReadinessResponseStatusOk       ReadinessResponseStatus = "ok"
+	ReadinessResponseStatusNotReady ReadinessResponseStatus = "not_ready"
+	ReadinessResponseStatusError    ReadinessResponseStatus = "error"
+)
+
+// AllValues returns all ReadinessResponseStatus values.
+func (ReadinessResponseStatus) AllValues() []ReadinessResponseStatus {
+	return []ReadinessResponseStatus{
+		ReadinessResponseStatusOk,
+		ReadinessResponseStatusNotReady,
+		ReadinessResponseStatusError,
+	}
+}
+
+// MarshalText implements encoding.TextMarshaler.
+func (s ReadinessResponseStatus) MarshalText() ([]byte, error) {
+	switch s {
+	case ReadinessResponseStatusOk:
+		return []byte(s), nil
+	case ReadinessResponseStatusNotReady:
+		return []byte(s), nil
+	case ReadinessResponseStatusError:
+		return []byte(s), nil
+	default:
+		return nil, errors.Errorf("invalid value: %q", s)
+	}
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler.
+func (s *ReadinessResponseStatus) UnmarshalText(data []byte) error {
+	switch ReadinessResponseStatus(data) {
+	case ReadinessResponseStatusOk:
+		*s = ReadinessResponseStatusOk
+		return nil
+	case ReadinessResponseStatusNotReady:
+		*s = ReadinessResponseStatusNotReady
+		return nil
+	case ReadinessResponseStatusError:
+		*s = ReadinessResponseStatusError
+		return nil
+	default:
+		return errors.Errorf("invalid value: %q", data)
+	}
+}

pkg/rest/oas_server_gen.go

@@ -0,0 +1,46 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"context"
+)
+
+// Handler handles operations described by OpenAPI v3 specification.
+type Handler interface {
+	// PerformPrediction implements performPrediction operation.
+	//
+	// Perform prediction.
+	//
+	// GET /api/v1/prediction
+	PerformPrediction(ctx context.Context, params PerformPredictionParams) (*PredictionResponse, error)
+	// ReadinessCheck implements readinessCheck operation.
+	//
+	// Readiness check.
+	//
+	// GET /ready
+	ReadinessCheck(ctx context.Context) (*ReadinessResponse, error)
+	// NewError creates *ErrorStatusCode from error returned by handler.
+	//
+	// Used for common default response.
+	NewError(ctx context.Context, err error) *ErrorStatusCode
+}
+
+// Server implements http server based on OpenAPI v3 specification and
+// calls Handler to handle requests.
+type Server struct {
+	h Handler
+	baseServer
+}
+
+// NewServer creates new Server.
+func NewServer(h Handler, opts ...ServerOption) (*Server, error) {
+	s, err := newServerConfig(opts...).baseServer()
+	if err != nil {
+		return nil, err
+	}
+	return &Server{
+		h:          h,
+		baseServer: s,
+	}, nil
+}

pkg/rest/oas_unimplemented_gen.go

@@ -0,0 +1,40 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"context"
+
+	ht "github.com/ogen-go/ogen/http"
+)
+
+// UnimplementedHandler is no-op Handler which returns http.ErrNotImplemented.
+type UnimplementedHandler struct{}
+
+var _ Handler = UnimplementedHandler{}
+
+// PerformPrediction implements performPrediction operation.
+//
+// Perform prediction.
+//
+// GET /api/v1/prediction
+func (UnimplementedHandler) PerformPrediction(ctx context.Context, params PerformPredictionParams) (r *PredictionResponse, _ error) {
+	return r, ht.ErrNotImplemented
+}
+
+// ReadinessCheck implements readinessCheck operation.
+//
+// Readiness check.
+//
+// GET /ready
+func (UnimplementedHandler) ReadinessCheck(ctx context.Context) (r *ReadinessResponse, _ error) {
+	return r, ht.ErrNotImplemented
+}
+
+// NewError creates *ErrorStatusCode from error returned by handler.
+//
+// Used for common default response.
+func (UnimplementedHandler) NewError(ctx context.Context, err error) (r *ErrorStatusCode) {
+	r = new(ErrorStatusCode)
+	return r
+}

pkg/rest/oas_validators_gen.go

@@ -0,0 +1,344 @@
+// Code generated by ogen, DO NOT EDIT.
+
+package rest
+
+import (
+	"fmt"
+
+	"github.com/go-faster/errors"
+	"github.com/ogen-go/ogen/validate"
+)
+
+func (s PerformPredictionProfile) Validate() error {
+	switch s {
+	case "standard_profile":
+		return nil
+	case "float_profile":
+		return nil
+	default:
+		return errors.Errorf("invalid value: %v", s)
+	}
+}
+
+func (s *PredictionResponse) Validate() error {
+	if s == nil {
+		return validate.ErrNilPointer
+	}
+
+	var failures []validate.FieldError
+	if err := func() error {
+		if value, ok := s.Request.Get(); ok {
+			if err := func() error {
+				if err := value.Validate(); err != nil {
+					return err
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "request",
+			Error: err,
+		})
+	}
+	if err := func() error {
+		if s.Prediction == nil {
+			return errors.New("nil is invalid value")
+		}
+		var failures []validate.FieldError
+		for i, elem := range s.Prediction {
+			if err := func() error {
+				if err := elem.Validate(); err != nil {
+					return err
+				}
+				return nil
+			}(); err != nil {
+				failures = append(failures, validate.FieldError{
+					Name:  fmt.Sprintf("[%d]", i),
+					Error: err,
+				})
+			}
+		}
+		if len(failures) > 0 {
+			return &validate.Error{Fields: failures}
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "prediction",
+			Error: err,
+		})
+	}
+	if len(failures) > 0 {
+		return &validate.Error{Fields: failures}
+	}
+	return nil
+}
+
+func (s *PredictionResponsePredictionItem) Validate() error {
+	if s == nil {
+		return validate.ErrNilPointer
+	}
+
+	var failures []validate.FieldError
+	if err := func() error {
+		if err := s.Stage.Validate(); err != nil {
+			return err
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "stage",
+			Error: err,
+		})
+	}
+	if err := func() error {
+		if s.Trajectory == nil {
+			return errors.New("nil is invalid value")
+		}
+		var failures []validate.FieldError
+		for i, elem := range s.Trajectory {
+			if err := func() error {
+				if err := elem.Validate(); err != nil {
+					return err
+				}
+				return nil
+			}(); err != nil {
+				failures = append(failures, validate.FieldError{
+					Name:  fmt.Sprintf("[%d]", i),
+					Error: err,
+				})
+			}
+		}
+		if len(failures) > 0 {
+			return &validate.Error{Fields: failures}
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "trajectory",
+			Error: err,
+		})
+	}
+	if len(failures) > 0 {
+		return &validate.Error{Fields: failures}
+	}
+	return nil
+}
+
+func (s PredictionResponsePredictionItemStage) Validate() error {
+	switch s {
+	case "ascent":
+		return nil
+	case "descent":
+		return nil
+	case "float":
+		return nil
+	default:
+		return errors.Errorf("invalid value: %v", s)
+	}
+}
+
+func (s *PredictionResponsePredictionItemTrajectoryItem) Validate() error {
+	if s == nil {
+		return validate.ErrNilPointer
+	}
+
+	var failures []validate.FieldError
+	if err := func() error {
+		if err := (validate.Float{}).Validate(float64(s.Latitude)); err != nil {
+			return errors.Wrap(err, "float")
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "latitude",
+			Error: err,
+		})
+	}
+	if err := func() error {
+		if err := (validate.Float{}).Validate(float64(s.Longitude)); err != nil {
+			return errors.Wrap(err, "float")
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "longitude",
+			Error: err,
+		})
+	}
+	if err := func() error {
+		if err := (validate.Float{}).Validate(float64(s.Altitude)); err != nil {
+			return errors.Wrap(err, "float")
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "altitude",
+			Error: err,
+		})
+	}
+	if len(failures) > 0 {
+		return &validate.Error{Fields: failures}
+	}
+	return nil
+}
+
+func (s *PredictionResponseRequest) Validate() error {
+	if s == nil {
+		return validate.ErrNilPointer
+	}
+
+	var failures []validate.FieldError
+	if err := func() error {
+		if value, ok := s.LaunchLatitude.Get(); ok {
+			if err := func() error {
+				if err := (validate.Float{}).Validate(float64(value)); err != nil {
+					return errors.Wrap(err, "float")
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "launch_latitude",
+			Error: err,
+		})
+	}
+	if err := func() error {
+		if value, ok := s.LaunchLongitude.Get(); ok {
+			if err := func() error {
+				if err := (validate.Float{}).Validate(float64(value)); err != nil {
+					return errors.Wrap(err, "float")
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "launch_longitude",
+			Error: err,
+		})
+	}
+	if err := func() error {
+		if value, ok := s.LaunchAltitude.Get(); ok {
+			if err := func() error {
+				if err := (validate.Float{}).Validate(float64(value)); err != nil {
+					return errors.Wrap(err, "float")
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "launch_altitude",
+			Error: err,
+		})
+	}
+	if err := func() error {
+		if value, ok := s.AscentRate.Get(); ok {
+			if err := func() error {
+				if err := (validate.Float{}).Validate(float64(value)); err != nil {
+					return errors.Wrap(err, "float")
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "ascent_rate",
+			Error: err,
+		})
+	}
+	if err := func() error {
+		if value, ok := s.BurstAltitude.Get(); ok {
+			if err := func() error {
+				if err := (validate.Float{}).Validate(float64(value)); err != nil {
+					return errors.Wrap(err, "float")
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "burst_altitude",
+			Error: err,
+		})
+	}
+	if err := func() error {
+		if value, ok := s.DescentRate.Get(); ok {
+			if err := func() error {
+				if err := (validate.Float{}).Validate(float64(value)); err != nil {
+					return errors.Wrap(err, "float")
+				}
+				return nil
+			}(); err != nil {
+				return err
+			}
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "descent_rate",
+			Error: err,
+		})
+	}
+	if len(failures) > 0 {
+		return &validate.Error{Fields: failures}
+	}
+	return nil
+}
+
+func (s *ReadinessResponse) Validate() error {
+	if s == nil {
+		return validate.ErrNilPointer
+	}
+
+	var failures []validate.FieldError
+	if err := func() error {
+		if err := s.Status.Validate(); err != nil {
+			return err
+		}
+		return nil
+	}(); err != nil {
+		failures = append(failures, validate.FieldError{
+			Name:  "status",
+			Error: err,
+		})
+	}
+	if len(failures) > 0 {
+		return &validate.Error{Fields: failures}
+	}
+	return nil
+}
+
+func (s ReadinessResponseStatus) Validate() error {
+	switch s {
+	case "ok":
+		return nil
+	case "not_ready":
+		return nil
+	case "error":
+		return nil
+	default:
+		return errors.Errorf("invalid value: %v", s)
+	}
+}

scripts/build_elevation.py

@@ -0,0 +1,155 @@
+#!/usr/bin/env python3
+"""
+Download ETOPO 2022 30-arc-second elevation data and convert to ruaumoko-compatible
+binary format (int16 little-endian, 21601 lat x 43200 lon, south-to-north).
+
+Output: ~1.74 GiB binary file.
+
+Usage: python3 build_elevation.py [output_path]
+  Default output: /srv/ruaumoko-dataset
+"""
+
+import sys
+import os
+import struct
+import tempfile
+import numpy as np
+
+CELLS_PER_DEGREE = 120
+NUM_LATS = 180 * CELLS_PER_DEGREE + 1  # 21601
+NUM_LONS = 360 * CELLS_PER_DEGREE      # 43200
+EXPECTED_SIZE = NUM_LATS * NUM_LONS * 2  # 1,866,326,400
+
+ETOPO_URL = "https://www.ngdc.noaa.gov/thredds/fileServer/global/ETOPO2022/30s/30s_surface_elev_netcdf/ETOPO_2022_v1_30s_N90W180_surface.nc"
+
+
+def download_etopo(output_path):
+    """Download ETOPO 2022 NetCDF and convert to ruaumoko binary format."""
+    try:
+        import xarray as xr
+    except ImportError:
+        print("ERROR: xarray is required. Install with: pip install xarray netcdf4")
+        sys.exit(1)
+
+    # Check if we can download directly or need a local file
+    nc_path = os.environ.get("ETOPO_NC_PATH")
+    if nc_path and os.path.exists(nc_path):
+        print(f"Using local ETOPO file: {nc_path}")
+    else:
+        print(f"Downloading ETOPO 2022 30-second data (~1.1 GB)...")
+        print(f"  URL: {ETOPO_URL}")
+        print(f"  (Set ETOPO_NC_PATH env var to use a pre-downloaded file)")
+
+        import urllib.request
+        with tempfile.NamedTemporaryFile(suffix=".nc", delete=False) as f:
+            nc_path = f.name
+
+        try:
+            urllib.request.urlretrieve(ETOPO_URL, nc_path, _progress)
+            print()
+        except Exception as e:
+            os.unlink(nc_path)
+            print(f"\nDownload failed: {e}")
+            print("\nAlternative: manually download ETOPO 2022 30s NetCDF from:")
+            print("  https://www.ncei.noaa.gov/products/etopo-global-relief-model")
+            print(f"  Then set ETOPO_NC_PATH=/path/to/file.nc and re-run")
+            sys.exit(1)
+
+    print(f"Opening NetCDF dataset...")
+    ds = xr.open_dataset(nc_path)
+
+    # ETOPO 2022 30s has:
+    # - lat: -90 to +90, 21601 points (south to north)
+    # - lon: -180 to +180, 43201 points
+    # We need:
+    # - lat: -90 to +90, 21601 points (south to north) ← same
+    # - lon: 0 to 360 (exclusive), 43200 points ← need to shift and drop last
+
+    z = ds["z"]  # elevation variable
+    print(f"  Shape: {z.shape}")
+    print(f"  Lat range: {float(z.lat.min())} to {float(z.lat.max())}")
+    print(f"  Lon range: {float(z.lon.min())} to {float(z.lon.max())}")
+
+    # Sort latitude south-to-north (should already be, but ensure)
+    z = z.sortby("lat")
+
+    # Shift longitude from [-180, 180] to [0, 360)
+    print("Shifting longitude to [0, 360)...")
+    z = z.assign_coords(lon=(z.lon % 360))
+    z = z.sortby("lon")
+
+    data = z.values
+    print(f"  Raw shape after sort: {data.shape}")
+
+    # Handle longitude dimension: drop last col if it wraps (43201 → 43200)
+    if data.shape[1] == NUM_LONS + 1:
+        data = data[:, :NUM_LONS]
+    elif data.shape[1] != NUM_LONS:
+        print(f"ERROR: unexpected lon dimension: {data.shape[1]}, expected {NUM_LONS} or {NUM_LONS+1}")
+        sys.exit(1)
+
+    # Handle latitude dimension: ETOPO 2022 is cell-centered (21600 rows),
+    # ruaumoko expects grid-registered (21601 rows including both poles).
+    # Pad by duplicating edge rows for the poles.
+    if data.shape[0] == NUM_LATS - 1:
+        print(f"  Padding latitude from {data.shape[0]} to {NUM_LATS} (adding north pole row)")
+        north_pole = data[-1:, :]    # duplicate +89.99... as +90
+        data = np.concatenate([data, north_pole], axis=0)
+    elif data.shape[0] != NUM_LATS:
+        print(f"ERROR: unexpected lat dimension: {data.shape[0]}, expected {NUM_LATS} or {NUM_LATS-1}")
+        sys.exit(1)
+
+    print(f"Final grid shape: {data.shape}")
+    print(f"Elevation range: {data.min():.1f} to {data.max():.1f} metres")
+
+    # Write as int16 little-endian
+    print(f"Writing to {output_path}...")
+    elev_int16 = np.clip(data, -32768, 32767).astype(np.dtype("<i2"))
+    elev_int16.tofile(output_path)
+
+    actual_size = os.path.getsize(output_path)
+    print(f"Written {actual_size:,} bytes (expected {EXPECTED_SIZE:,})")
+    if actual_size == EXPECTED_SIZE:
+        print("SUCCESS")
+    else:
+        print("WARNING: size mismatch!")
+
+    ds.close()
+
+    # Spot check
+    verify(output_path)
+
+
+def verify(path):
+    """Quick spot-check of the elevation dataset."""
+    data = np.memmap(path, dtype="<i2", mode="r", shape=(NUM_LATS, NUM_LONS))
+
+    tests = [
+        ("Mt Everest (~28.0N, 86.9E)", 28.0, 86.9, 8000, 9000),
+        ("Dead Sea (~31.5N, 35.5E)", 31.5, 35.5, -500, 0),
+        ("Pacific Ocean (~0N, 180E)", 0.0, 180.0, -6000, 0),
+        ("Auburn AU (~-34.0S, 138.7E)", -34.03, 138.69, 200, 400),
+    ]
+
+    print("\n  Spot-check:")
+    for name, lat, lon, lo, hi in tests:
+        lat_idx = int((lat + 90) * CELLS_PER_DEGREE)
+        lon_idx = int(lon * CELLS_PER_DEGREE)
+        val = int(data[lat_idx, lon_idx])
+        ok = "OK" if lo <= val <= hi else "FAIL"
+        print(f"    {name}: {val}m [{ok}] (expected {lo}-{hi})")
+
+
+_last_pct = -1
+def _progress(block_num, block_size, total_size):
+    global _last_pct
+    if total_size > 0:
+        pct = int(block_num * block_size * 100 / total_size)
+        if pct != _last_pct and pct % 5 == 0:
+            _last_pct = pct
+            print(f"  {pct}%...", end="", flush=True)
+
+
+if __name__ == "__main__":
+    output = sys.argv[1] if len(sys.argv) > 1 else "/srv/ruaumoko-dataset"
+    download_etopo(output)