[lilyshen0722]

Unblocks the merge queue. Every PR's backend shard 3, and the queue's own runs (the #3107 group, for one), have been red since 00:00Z on 11-01 on a single test:

dailyDigestService.membership.test.js › "a scheduled run takes only the people for whom it is the hour"

Cause: the test built laEight as 15:01 UTC on the current date and asserted that this is 08:00 in America/Los_Angeles. That holds only under PDT (UTC-7). Daylight saving ended at 09:00Z on 2026-11-01, so from that UTC date on, 15:01Z is 07:01 PST and the assert fails. It would have stayed red until 2027-03-14. The service isn't involved.

Fix (test only): the case now runs on fixed instants, never today's date. generateAllDailyDigests takes at and reads no other clock on the scheduled path. So pinning at, and deriving lastActive from it, fixes the test for good, with no fake timers. It's now three cases:

• 2026-10-17T15:01Z, 08:01 PDT: Los Angeles is due.
• 2026-12-15T15:01Z, 07:01 PST: Los Angeles is not due. This is the reverse case.
• 2026-12-15T16:01Z, 08:01 PST: Los Angeles is due.

The no-zone person is never due at any of them, because its hour is 06:00 UTC.

Tests:

• The whole file passes, 26 of 26, on Node 22 in a container with in-memory Mongo.
• Mutation check: with dueAt hard-coded to 15 UTC for any zone, both winter cases fail.
• The only other Los Angeles test in the backend (timeZone.test.js) already uses a fixed date.

Tier 1, test only. Its one review round is the writer's subagent review, then CodeRabbit and CI.

🤖 Generated with Claude Code

https://claude.ai/code/session_015AKgpQmb6BbxDrAtw45bgN

[coderabbitai]

No actionable comments were generated in the recent review.

Recent review info

Run configuration

• Source mode: Auto
• Repository: Team-Commonly/commonly
• Branch: stack/digest-hour-dst-test
• File: .coderabbit.yaml
• Commit: f23cb04
• Layers: Repository YAML
• Review profile: QUIET
• Plan: Advanced
• Run ID: d4be11a2-3f0e-4e0e-980b-b9a17874504f

Commits

Reviewing files that changed from the base of the PR and between 5ecd7b3 and f23cb04.

Files selected for processing: 1

• backend/__tests__/unit/services/dailyDigestService.membership.test.js

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 1 remain after this review.

Walkthrough

The daily digest membership test now uses fixed summer and winter instants to check due-hour selection for Los Angeles and no-timezone users.

Changes: Daily digest timezone test

Layer / File(s)	Summary
Scheduled-run timezone assertions backend/__tests__/unit/services/dailyDigestService.membership.test.js	The test checks Los Angeles selection at 15:01 UTC in summer and 16:01 UTC in winter. It also checks no-timezone user selection at 06:01 UTC in winter. The comment notes that Los Angeles’s 08:00 UTC offset depends on the date.

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Other

Possibly related PRs

• Team-Commonly/commonly#2618: Adds watcher-driven users to the scheduled candidate query and tests scheduled task-only delivery.

Merge Risk: Minimal · up to f23cb

This test-only change provides reliable coverage for summer, winter, and no-timezone digest scheduling behavior.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title names the changed test and the fix: it pins the digest-hour case to fixed summer and winter instants, which matches the test-only change in dailyDigestService.membership.test.js. It also sta…
Description check		The description states the failing test, the root cause (a fixed UTC-to-Los Angeles assumption that breaks after DST ended on 2026-11-01), and the test-only fix with three fixed-instant cases. It also…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Title check

Explanation

The title names the changed test and the fix: it pins the digest-hour case to fixed summer and winter instants, which matches the test-only change in dailyDigestService.membership.test.js. It also states the CI-unblocking purpose. The title is specific and accurate, so it passes.

Full details: Description check

Explanation

The description states the failing test, the root cause (a fixed UTC-to-Los Angeles assumption that breaks after DST ended on 2026-11-01), and the test-only fix with three fixed-instant cases. It also lists the test results and a mutation check. It directly describes the changeset, so it passes.

Finishing Touches

Generate docstrings

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• Create a new PR

Generate unit tests (beta)

• Commit to this branch
• Create a new PR

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

[lilyshen0722]

One review round (D218), recorded at f23cb04: the writer's own subagent review, then CodeRabbit and CI.

• Subagent review: 0 blocking, 4 non-blocking. It verified the 2026 DST dates, checked that generateAllDailyDigests reads only at on the scheduled path, and found no other today-dependent zone test in backend/__tests__. Two nits are fixed in f23cb04: a stale comment, and a no-zone 06:01Z row so the no-zone assertion isn't vacuous. The other two (a redundant helper check, the assertion shape) were folded in.
• CodeRabbit: passed, with no threads.
• CI: Test & Coverage passed, and Backend tests 3/3 is green again, which is the shard this fixes. E2E Tests hit its 30-minute limit. It isn't a required check, and this PR changes one backend unit-test file.

GATE: PASS