[danielededo]

Step 2. Stacked on #28 (the sport catalogue), so this PR targets that branch and its diff shows only step 2. GitHub retargets it to main when #28 is merged.

Garmin records a strength session as FIT sport training, sub-sport strength_training. Until now it was stored as other and shown with the few metres of drift a wrist logs in a gym, plus a pace for it.

What changes

Catalogue (app/services/sports.py)

• New has_distance (default True) and fit_sub (FIT sub-sport aliases) on every sport.
• New strength entry: has_distance=False, fit_sub=("strength_training",).
• sport_from_file("fit", sport, sub_sport): a sub-sport the catalogue lists wins over the sport. Unlisted sub-sports change nothing, so indoor_rowing under fitness_equipment is still other, and road under cycling is still cycling.
• GET /api/sports now includes has_distance.

FIT parser

• Reads the sub-sport from the session, or from the sport message if the session has none, as it already did for the sport.
• Keeps the declared sport in raw_data.declared_sport beside sub_sport. TCX and GPX already kept theirs.

New scripts/backfill_sports.py

• Re-applies the catalogue to activities already stored, using what each file declared. FIT rows stored before declared_sport existed can still be moved by sub-sport.
• Renames an activity only if it still has the generated name (Other 2026-06-24 becomes Strength 2026-06-24). A name from the file, or one you chose, stays.
• Has --dry-run, and is safe to re-run.

Dashboard, for a sport without distance

• Hidden: distance, pace and climb (detail, table, records), the route panel, comparison along a distance axis, and the bar in the per-sport breakdown.
• Kept: time, heart rate, zones and load.
• formatPaceOrSpeed answers — for such a sport, so every place that shows pace is covered.
• The figures are still stored as the file wrote them.

Docs: README (feature list, a backfill step under "Updating", "Adding a sport", test counts) and three new paragraphs in docs/DESIGN.md.

Verified

• Backend: pytest 389 passed (15 new: parser, catalogue and backfill), coverage 96.8%, ruff lint and format.
• On PostgreSQL 16, using the scratch database from the import tests:
  • A synthetic Garmin strength FIT (sport 10, sub-sport 20, no GPS) is stored as strength / Strength 2026-06-24, with declared_sport: training and sub_sport: strength_training.
  • With that row reset to other, the backfill moves it back and renames it.
  • A dry run over the 300 running and cycling activities moves nothing.
• Frontend: vitest 252 passed (6 new in tests/strength.test.jsx), eslint and build. All 6 new tests fail when run against the components without this change.

Not covered

• A real strength FIT file. No public one exists (the Garmin SDK samples and the fixtures of python-fitparse and fitdecode have none), so this follows Garmin's documented sport and sub-sport values, tested on files built from the format spec.
• Sets, reps and weights: that's step 3.