# Tasks: enterprise-tides

**Change ID**: enterprise-tides
**Package**: `@suaveplan/tides`
**Target path**: `universal/geo/tides`
**Prerequisite packages on Verdaccio**: `@suaveplan/error`, `@suaveplan/types`, `@suaveplan/geo`

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## 1. Scaffold

- [ ] Create `universal/geo/tides/` with `src/`, `tests/`, `src/__benchmarks__/` and all feature subdirectories per the layout in `proposal.md`.
- [ ] Write `package.json` at version `0.1.0` with `"type": "module"`, `"sideEffects": false`, correct `exports` map, `dependencies`, and `devDependencies`.
- [ ] Write `tsconfig.json` extending `@suaveplan/typescript-config/library.json`.
- [ ] Write `vitest.config.ts` using `createTestConfig()` from `@suaveplan/testing/config`.
- [ ] Add `lint`, `typecheck`, `test`, `test:coverage`, `build`, `docs:check` scripts.

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## 2. Types + errors

- [ ] `src/types/common.ts` — `TidalPort`, `TidalConstituent`, `TidePrediction`, `TideTable`, `TidePredictorOptions`.
- [ ] `src/types/common.md` (≥200 words, both examples, API reference).
- [ ] `src/error-codes.ts` — `TidesErrorCode` (5 codes), metadata, register, eager call.
- [ ] `src/constants/index.ts` — `DEGREES_PER_HOUR`, `EPOCH_1900` (for ADMIRALTY-style time base).
- [ ] `src/types/schemas.ts` + `schemas.md` — Zod schemas.

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## 3. Core modules

- [ ] **`src/core/harmonic-engine/`** — `harmonicHeight(constituents, time): number`: for each constituent compute `amplitude * cos(speed * t + phase)` where `t` is hours since a reference epoch; sum all constituents. Tests: known published tide heights at 3 reference ports at known times (deterministic); result in `[-maxAmplitude, +maxAmplitude]`.
- [ ] **`src/core/extrema-finder/`** — `findExtrema(predictor, portId, from, to): TidePrediction[]`: samples at 15-minute intervals, applies 3-point peak/trough detection, refines each extremum to 1-minute resolution via golden-section search. Tests: at least one high and one low in a 24-hour window; alternating high/low ordering; extrema `height` is a local maximum/minimum relative to neighbours.
- [ ] **`src/data/ticon-loader/`** — `parseTiconData(raw): TidalPort[]`: parses a structured text format (space-delimited columns: port code, name, lat, lng, constituent rows). `loadBuiltinPorts()`: imports `builtin-ports.json` (bundled data for ≥30 UK ports). Tests: round-trip parse for 3 manually constructed port entries.
- [ ] **`src/core/tide-predictor/`** — `TidePredictor`: `loadPort`, `listPorts`, `predict(portId, time)`, `predictRange`, `findExtrema`, `generateTable`, `generateTables`, `stream(portId, from, to, interval)`. `stream` is an `AsyncGenerator<TidePrediction>`. `generateTable` includes `highWaters`, `lowWaters`, `range`, `meanLevel`. Tests: predict at known time matches `harmonicHeight` directly; generateTable for 24h has ≥2 extrema; stream yields predictions in order; stream abort exits.
- [ ] **`src/data/builtin-ports.json`** — bundled TICON-format data for ≥30 UK ports (curated from publicly available harmonic constituent data).

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## 4. OTel instrumentation

- [ ] Span `tides.predict_range` with attributes `tides.port_id`, `tides.interval_minutes`; counter `tides.table_generate_total`; histogram `tides.predict_duration_ms`.

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## 5. Property-based tests (`tests/property.test.ts`)

- [ ] Harmonic height bounds: for arbitrary constituent arrays with amplitudes ≤5 m, result is always in `[-sum(amplitudes), +sum(amplitudes)]`.
- [ ] Extrema ordering: `findExtrema` always returns alternating `high`/`low` types.
- [ ] Prediction continuity: for any two adjacent predictions 1 minute apart, `|height_t+1 - height_t| < 0.5` (no discontinuities).

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## 6. Benchmarks (`src/__benchmarks__/tides.bench.ts`)

- [ ] `predictRange` for 7-day window at 1-minute resolution for one port.
- [ ] `findExtrema` for 30-day window.

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## 7. Docs + verify

- [ ] One `.md` per implementation file (≥200 words, both examples, API reference). Root `README.md`.
- [ ] `bunx turbo lint typecheck test --filter=@suaveplan/tides` — green.
- [ ] `bunx turbo test:coverage --filter=@suaveplan/tides` — 100%.
- [ ] `bun scripts/publish.ts --package @suaveplan/tides`.
- [ ] Archive: `openspec/archive/2026-04-24-enterprise-tides/`.