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trails/openspec/changes/elevation-profile-hardening/tasks.md
Ullrich Schäfer 29be9cbe5f
feat(gpx): apply elevation cleaning to totals + profile chart 
Task group 2 (part a) of elevation-profile-hardening — wire the group-1
primitives into the headline stat and the chart.

- computeElevation (parse.ts): despike each segment's elevation sequence,
  then take filteredTotals; gain/loss are now noise-filtered (no more
  20–50% inflation from per-point jitter), the profile is built from the
  despiked data, and additive gainRaw/lossRaw expose the unfiltered sums.
- elevationSeries: despike per segment (no cross-trkseg interpolation)
  before downsampling, so the chart and the headline totals derive from
  the same cleaned data.
- types.ts: GpxData.elevation gains gainRaw/lossRaw (additive).

Well-formed monotonic climbs are unchanged (steps exceed the 5 m
threshold → filtered == raw); a shared noisy-track test proves jitter is
filtered and a 300 m single-point spike is interpolated out of both the
totals and the chart.

Verified: gpx 111/111; full pnpm typecheck 13/13, lint 13/13, test 11/11
(journal + planner compile with the additive fields).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-14 00:56:36 +02:00

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1. Cleaning primitives

  • 1.1 Create packages/gpx/src/elevation-clean.ts with despike(points, opts?) — opposite-sign slope-outlier detection (default MAX_SLOPE_PERCENT = 100) with linear interpolation, operating per segment on { distance, elevation } sequences
  • 1.2 Add filteredTotals(points, opts?) to the same module — hysteresis accumulator (default NOISE_THRESHOLD_M = 5) returning { gain, loss, gainRaw, lossRaw } with the raw-fallback rule (filtered zero + raw non-zero → report raw)
  • 1.3 Add cumulativeFilteredTotals(points, opts?) returning per-point running filtered ascent/descent arrays (for per-day splits)
  • 1.4 Write elevation-clean.test.ts: isolated spike interpolated; steep monotonic climb untouched; no cross-segment interpolation; ±2 m jitter → 0 totals; multi-leg climb counted fully; near-flat raw fallback; cumulative arrays sum to totals

2. Wire into existing computations

  • 2.1 Update computeElevation in packages/gpx/src/parse.ts to despike per segment, then use filteredTotals; keep gain/loss/profile shape and expose gainRaw/lossRaw as additional fields (profile built from despiked data)
  • 2.2 Update elevationSeries in packages/gpx/src/elevation-series.ts to build from despiked points (despike per segment before flattening)
  • 2.3 Update compute-days.ts to build its cumulative ascent/descent arrays via cumulativeFilteredTotals over the despiked track
  • 2.4 Update/extend existing tests (parse.test.ts, elevation-series.test.ts, compute-days.test.ts) with a shared noisy-track fixture; assert chart series, totals, and day sums agree

3. Verification

  • 3.1 Confirm no consumer changes needed: typecheck journal + planner; spot-check gpx-save.server.ts, detail loaders, and planner computeDays usage compile and behave
  • 3.2 Manual sanity check: parse a real noisy activity GPX (e.g. an existing import fixture) and compare gain before/after — filtered value should drop noticeably and match the chart
  • 3.3 Run pnpm typecheck && pnpm lint && pnpm test and the journal/planner e2e suites