e1e3dc5c81
Builds on the merged A-only proposal. Broadens the capability: - breakdown now on routes AND activities; - Path 1 (sync) unchanged: BRouter waytags → breakdown at Planner save; - Path 2 (async): a `surface-backfill` pg-boss job map-matches geometry to OSM via Overpass for imports/uploads/older rows, stores the breakdown, and pushes a `surface_breakdown` SSE event so an open detail page fills in live; - privacy note: backfill sends geometry to Overpass → route via the proxy / self-hostable Overpass; documented in the manifest. Validates with `openspec validate --strict`. Specs only; no code. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
90 lines
4.6 KiB
Markdown
90 lines
4.6 KiB
Markdown
## Context
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The Planner computes accurate per-coordinate surface/highway from BRouter's
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`WayTags` (`apps/planner/.../route-merge.ts` → `EnrichedRoute`) and colours the
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line with it, but it's session-only: `api.save-to-journal` POSTs only `{ gpx }`,
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`routes` has no surface column, GPX carries no surface tags. The repo already
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has a typed pg-boss job system (`apps/journal/app/jobs/payloads.ts`,
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`@trails-cool/jobs`), an SSE broker (`/api/events` + EventSource hooks, e.g.
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`useUnreadNotifications`), and an Overpass proxy used for Planner POIs
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(`apps/planner/.../overpass.ts`, `/api/overpass`).
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## Goals / Non-Goals
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**Goals**
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- Surface + waytype bars on route **and** activity detail.
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- Two derivation paths: free/accurate for Planner routes; async backfill for
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everything else, with a live SSE update.
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**Non-Goals (v1)**
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- Colouring the Journal **map line** by surface (needs per-segment data, not the
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summary; a clean follow-up).
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- Re-backfilling on every geometry edit (backfill is one-shot per row unless
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re-triggered).
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## Decisions
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### D1: Two derivation paths into one stored summary
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Both paths produce the same compact, distance-weighted summary —
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`{ surface: { asphalt: <m>, gravel: <m>, … }, highway: { … } }` (metres per
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category) — stored as nullable `surface_breakdown` jsonb on `routes` and
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`activities`. The bars need proportions, not geometry, so we store a summary,
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not per-segment data (per-segment is a future map-colouring concern).
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- **Path 1 — synchronous, Planner routes (accurate, free).** The Planner has
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100%-accurate per-segment tags; compute the summary at save and persist via an
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extra optional `surfaceBreakdown` field in the handoff. No external call.
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- **Path 2 — async backfill, everything else (best-effort).** For a row with
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geometry but no summary, a job map-matches to OSM and computes it (D2).
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### D2: The async backfill job
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A typed `surface-backfill` pg-boss job keyed by `{ kind: "route" | "activity",
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id }`:
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1. Load the geometry; bail if absent or already has a summary.
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2. Query Overpass for `way[highway]` within the route bbox (a journal-side
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client mirroring the Planner's `buildQuery`/`parseResponse` + rate-limit
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handling).
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3. **Map-match**: for each route segment, find the nearest OSM way and read its
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`surface`/`highway`; bucket the segment's length. Unmatched/untagged →
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`unknown`.
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4. Store the summary; emit the SSE event (D3).
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- **Triggers:** enqueued after a GPX import (Komoot/Garmin) and after a manual
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upload; plus a one-off sweep job to backfill pre-existing rows. Optionally
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enqueued on-demand when a detail page without a summary is opened.
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- **Resilience:** pg-boss retries cover Overpass rate-limits/outages; the job is
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idempotent (skips if a summary already exists) and best-effort (failure leaves
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the row with no bars, not an error).
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### D3: SSE live update
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On backfill completion the job publishes a `surface_breakdown` SSE event
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(payload: `{ kind, id }`) via the existing broker. The detail page subscribes
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(EventSource hook) and, when the event matches the row it's showing, re-fetches
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the breakdown and fills the bars — so a user who opened the page before the job
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finished sees it appear without reloading. While a backfill is known to be
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in-flight, the page may show a small "computing…" affordance.
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### D4: Rendering
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A `SurfaceBreakdown` component: one horizontal stacked bar per dimension
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(surface, then waytype), segments sized by percentage and coloured via
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`SURFACE_COLORS`/`HIGHWAY_COLORS` (`DEFAULT_*` for unknown), with a legend
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(category · km · %, largest first). Unknown/unmapped tags collapse into "other".
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Hidden when the summary is null/empty. Labels via i18n; distances via `stats.ts`.
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### D5: Privacy (backfill sends geometry to Overpass)
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Path 1 sends nothing externally. Path 2's Overpass query exposes a route's
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bounding box to the Overpass endpoint — a real consideration for a privacy-first
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app. Mitigations: route the backfill through the **proxied / self-hostable**
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Overpass (the parked `self-host-overpass` idea removes the third-party entirely),
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and only the bbox + geometry needed for matching is sent. We document the
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backfill's external lookup in the privacy manifest; a self-hosted Overpass is the
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clean long-term answer.
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## Risks / Trade-offs
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- **Map-matching is approximate** — nearest-way snapping mismatches at junctions
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/ parallel ways; acceptable for a proportional overview, and Path 1 (exact) is
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preferred whenever available.
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- **Overpass cost/limits** — bounded by the async queue + retries; the sweep
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should throttle. A self-hosted Overpass removes the ceiling.
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- **Two code paths** — both converge on one stored summary + one renderer, so
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only the *derivation* differs.
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