trails/openspec/changes/archive/2026-07-16-fit-parsing-hardening/tasks.md

1. Fixtures first

• 1.1 Collect fixture FIT files — adapted: per the chosen approach, cases are driven by mocked fit-file-parser output in fit.test.ts (pause, multisession, indoor no-GPS, corrupt coords/missing-timestamp) rather than binary files. Real device binaries can be added later without changing the converter.
• 1.2 Parser events/sessions shapes captured as the FitEvent/FitSession types + code comments in fit.ts, and exercised by the mocked-parser tests.

2. Converter

• 2.1 Segmentation: split on timer stop/start event pairs, fallback on record gaps > 5 min (named constants)
• 2.2 Session slicing: records windowed per session, one-or-more segments per session, single-session unchanged
• 2.3 Validation gates: finite/in-range coordinates, timestamp required, non-finite altitude → undefined; prefer enhanced_altitude (speed isn't emitted to GPX so its preference is moot)
• 2.4 Return { gpx, sport } with the FIT→SportType mapping table; update call sites (Wahoo importer + webhook, Garmin importer) — provider-explicit type wins, FIT sport is fallback
• 2.5 Unit tests over the fixtures: segment counts (pause becomes a segment boundary, which is what keeps moving time honest), corrupt-record drops, enhanced-altitude preference, sport mapping, no-GPS returns null gpx

3. Verification

• 3.1 Re-run the Wahoo importer test suite; confirm existing single-session imports produce identical stats (14 pass; mock updated to the {gpx, sport} shape)
• 3.2 Run pnpm typecheck && pnpm lint && pnpm test — all green