babymonitor/plan.md

Investigation Plan: Bedtime Graph Issue

Objective

Investigate why the "Bedtime" graph shows unexpected times when a specific bedtime_ref is set.

Current Understanding

• The BedtimePlot.tsx component displays a graph where the Y-axis (or values) are formatted using formatMinutesAfter(value, bedtime_ref).
• The data comes from the /api/stats/wake-sleep-times endpoint.
• The backend calculates bedtime_minutes based on sessions that started on or before the bedtime_ref.

Investigation Steps

Step 1: Analyze Backend Logic

• Examine get_wake_sleep_times in backend/app/routers/stats.py to understand how bedtime_minutes is calculated.
• Verify if the logic correctly identifies "bedtime" for various sleep session scenarios (e.g., sessions crossing midnight).
• Identify potential edge cases where the s.start_time.time() <= b_ref_time condition might be problematic.

Step 2: Analyze Frontend Logic

• Examine BedtimePlot.tsx and useStats.ts to see how the data is consumed and formatted.
• Understand how formatMinutesAfter interacts with the values returned by the backend.

Step 3: Data Simulation & Verification

• Create a set of test cases (mocked data) representing different sleep scenarios.
• Manually calculate the expected bedtime_minutes for these scenarios using the current logic.
• Compare with what the user reported to confirm the bug's nature.

Step 4: Propose and Implement Fixes

• Refine the backend logic to better represent "bedtime" if current logic is insufficient.
• Ensure the frontend correctly displays the intended time.
• Verify that changes do not break other parts of the stats page (e.g., Wakeup times).

Future Tasks

• Run tests to ensure correctness after implementation.
• Finalize documentation/explanation of the fix.