fix(test): resolve flaky test_midnight_heartbeats boundary condition

[TimeToBuildBob]

Summary

Fixes the intermittently failing test_midnight_heartbeats test (seen in ActivityWatch/activitywatch#1211 CI as assert 9 == 8).

Root cause: The test creates events spanning midnight, then queries events "after midnight." Two issues caused non-deterministic results:

1. midnight retained residual microseconds from datetime.now(), making the exact boundary non-deterministic across runs
2. Event 9 (at 23:59 with 1-min duration) has endtime exactly at midnight, and the server's endtime >= start_query SQL condition sometimes includes it

Fix:

• Zero out seconds/microseconds on the start timestamp for deterministic boundaries
• Add a 1ms offset to the query start to avoid the ambiguous boundary where events ending exactly at midnight could be included by the >= condition

Test plan

• Existing test_midnight_heartbeats passes consistently (no more flaky failures)
• Other midnight tests unaffected

---

Important

Fixes flaky test_midnight_heartbeats by ensuring deterministic timestamp boundaries and adding a 1ms offset to avoid boundary ambiguity.

• Behavior:
  • Fixes flaky test_midnight_heartbeats in test_client.py by ensuring deterministic timestamp boundaries.
  • Zeroes out seconds/microseconds in midnight to prevent non-deterministic boundary matching.
  • Adds 1ms offset to query_start to avoid including events ending exactly at midnight.
• Test Plan:
  • Ensures test_midnight_heartbeats passes consistently.
  • Confirms other midnight tests remain unaffected.

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[ellipsis-dev]

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[greptile-apps]

Greptile Summary

Fixes intermittent test failures in test_midnight_heartbeats by addressing timing precision issues around midnight boundaries.

The fix applies two changes:

• Zeros out seconds and microseconds when creating the midnight boundary timestamp to ensure deterministic test behavior across runs
• Adds a 1ms offset to the query start time to avoid the ambiguous boundary condition where events ending exactly at midnight could be included or excluded based on the >= SQL condition

The root cause was non-deterministic microsecond values from datetime.now() being retained in the midnight calculation, causing the test to sometimes see 8 events and sometimes 9 events after midnight depending on whether event 9 (ending exactly at midnight) was included in the query results.

Confidence Score: 5/5

• This PR is safe to merge with no risk
• The changes are minimal, well-documented, and directly address a specific flaky test issue. The fix adds deterministic timestamp handling by zeroing out seconds/microseconds and includes a 1ms offset to avoid boundary ambiguity. This is a standard approach for fixing timing-related test flakiness and does not affect production code.
• No files require special attention

Important Files Changed

Filename	Overview
tests/test_client.py	Fixes flaky test by zeroing seconds/microseconds and adding 1ms offset to avoid boundary ambiguity

_{Last reviewed commit: 7eeec25}

[greptile-apps]

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[TimeToBuildBob]

Fixed Black formatting failure — collapsed the multi-line get_events() call to a single line in 61f046d. CI should be green now.