---
phase: 02-flexible-sets
plan: "02"
subsystem: api
tags: [express, postgres, react, fetch, delete, workout-logs]

# Dependency graph
requires:
  - phase: 02-flexible-sets
    plan: "01"
    provides: ExerciseCard with handleDeleteSet calling optional onDeleteSet prop (stub — wired here)
provides:
  - DELETE /api/logs endpoint in backend/src/index.js
  - deleteLog function in App.jsx calling DELETE /api/logs
  - onDeleteSet prop wired from App.jsx -> WorkoutPage -> ExerciseCard
affects: [03-custom-workouts, backend-logging]

# Tech tracking
tech-stack:
  added: []
  patterns: [DELETE endpoint with composite key (user_id, program_exercise_id, date, set_number), optimistic local state removal mirrors DB delete]

key-files:
  created: []
  modified:
    - backend/src/index.js
    - frontend/src/App.jsx
    - frontend/src/pages/WorkoutPage.jsx

key-decisions:
  - "No authMiddleware on DELETE /api/logs — consistent with existing POST /api/logs which also passes user_id in body"
  - "deleteLog silently ignores 404 responses — backend handles non-existent row gracefully (unlogged sets deleted mid-session)"
  - "Local logs state updated optimistically after DELETE regardless of 404 — ensures UI stays consistent even for never-logged sets"

patterns-established:
  - "Composite-key delete: (user_id, program_exercise_id, date, set_number) is the unique identifier for a workout set log row"
  - "Prop threading: deleteLog lives in App.jsx, flows as onDeleteSet -> WorkoutPage -> ExerciseCard without intermediate handlers"

# Metrics
duration: 2min
completed: 2026-02-21
---

# Phase 2 Plan 02: Flexible Sets — Backend DELETE Endpoint and Frontend Wiring Summary

**DELETE /api/logs endpoint deletes workout_logs rows by composite key; deleteLog in App.jsx propagates through WorkoutPage to ExerciseCard, removing orphaned set rows from DB when user deletes a set**

## Performance

- **Duration:** ~2 min
- **Started:** 2026-02-21T17:44:02Z
- **Completed:** 2026-02-21T17:45:45Z
- **Tasks:** 2
- **Files modified:** 3

## Accomplishments

- Backend DELETE /api/logs endpoint: deletes matching workout_logs row by composite key (user_id, program_exercise_id, date, set_number), returns 200+id on success, 404 if not found
- deleteLog async function added to App.jsx alongside logSet: sends DELETE fetch, removes entry from local logs state on success
- Full prop chain wired: App.jsx onDeleteSet={deleteLog} -> WorkoutPage signature updated to accept onDeleteSet -> ExerciseCard receives onDeleteSet prop (was already calling it if provided from plan 01)
- Frontend build passes cleanly after changes

## Task Commits

Each task was committed atomically:

1. **Task 1: Add DELETE /api/logs endpoint to backend** - `f9eb6cc` (feat)
2. **Task 2: Wire deleteLog through App.jsx and WorkoutPage to ExerciseCard** - `175434f` (feat)

**Plan metadata:** committed with docs commit (docs)

## Files Created/Modified

- `backend/src/index.js` - Added DELETE /api/logs route (21 lines) after POST /api/logs, same composite key pattern
- `frontend/src/App.jsx` - Added deleteLog function (20 lines), added onDeleteSet={deleteLog} prop to WorkoutPage render
- `frontend/src/pages/WorkoutPage.jsx` - Updated function signature to accept onDeleteSet, passed onDeleteSet to each ExerciseCard

## Decisions Made

- **No auth on DELETE /api/logs:** POST /api/logs has no authMiddleware — DELETE matches that pattern for consistency; user_id from body provides identity
- **Silent 404 handling:** If a set was never logged (user added then immediately deleted without completing), the DELETE returns 404. deleteLog catches silently — the row never existed, no cleanup needed
- **Optimistic state update:** Local logs state is always updated (filter out the set_number) regardless of whether the DELETE returned 200 or 404, since in both cases the set should not appear in the UI

## Deviations from Plan

None — plan executed exactly as written.

## Issues Encountered

None — build passed cleanly after both tasks. Backend syntax verified with `node --check`.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness

- Phase 2 (Flexible Sets) is now complete: ExerciseCard supports dynamic set lists (plan 01), and deleting a logged set removes it from the database (plan 02)
- Ghost sets can no longer reappear after page reload — deleted sets are removed from both frontend state and backend DB
- Phase 3 (Custom Workouts) requires new DB tables (custom_workouts, custom_workout_exercises) and a source_type column on workout_logs — schema migration needed before Phase 3 planning

## Self-Check: PASSED

- backend/src/index.js: FOUND
- frontend/src/App.jsx: FOUND
- frontend/src/pages/WorkoutPage.jsx: FOUND
- 02-02-SUMMARY.md: FOUND
- Commit f9eb6cc (Task 1): FOUND
- Commit 175434f (Task 2): FOUND
- DELETE /api/logs in backend: FOUND
- deleteLog in App.jsx: FOUND
- onDeleteSet prop wired through WorkoutPage: FOUND

---
*Phase: 02-flexible-sets*
*Completed: 2026-02-21*