fix: use configured Location for all schedule evaluations #2312

[four-bytes-robby]

Closes #2312

Problem

The scheduler had a timezone asymmetry: start schedules and one-off schedules used raw now (system clock time) while stop/restart schedules converted now to the configured cfg.Location. When DAGU_TZ is configured to a different timezone than the server's local time, start schedules, one-off schedules, and catchup computations fire at the wrong wall-clock time.

Root Cause

The misleading comment in tick_planner.go claimed robfig/cron applies the schedule's timezone internally — but the 5-field standard parser has no timezone support (no CRON_TZ=).

Additionally, os.Setenv("TZ", cfg.TZ) partially masks the bug by making time.Local == cfg.Location, but any code path that creates times without going through time.Now() (persisted watermarks, replay times, concurrent access) carries the wrong location.

Fix

Use now.In(tp.cfg.Location) consistently for ALL schedule evaluations:

Location	Change
Plan() start schedules	now → evalTime (now.In(cfg.Location))
Plan() one-off schedules	now → evalTime
Init() one-off reconciliation	tp.cfg.Clock() → tp.cfg.Clock().In(tp.cfg.Location)
recomputeBuffer() catchup	tp.cfg.Clock() → tp.cfg.Clock().In(tp.cfg.Location)

evalTime is now computed once at the top of Plan() and used in all four schedule loops (start, stop, restart, one-off).

Impact

• Remote DAGs with timezone-aware schedules now evaluate correctly
• Consistent with existing stop/restart behavior
• No behavior change when cfg.Location == time.Local
• All existing scheduler tests pass

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Summary by cubic

Fix a timezone mismatch in the scheduler. All schedules now use the configured location, so triggers fire at the expected wall-clock time when DAGU_TZ differs from the server timezone. Fixes #2312.

• Bug Fixes
  • Use a single evalTime := now.In(tp.cfg.Location) for all checks in Plan() (cron start and one-off).
  • Convert tp.cfg.Clock() to tp.cfg.Location in Init() reconciliation and recomputeBuffer() catchup.
  • Avoid relying on robfig/cron 5-field parser for timezone handling; no change when cfg.Location == time.Local.

^{Written for commit 7249a67. Summary will update on new commits.}

Summary by CodeRabbit

• Bug Fixes
  • Fixed scheduler timing evaluation to consistently apply configured timezone settings across all schedule due-time checks. Resolves potential timing misalignment issues when using non-UTC timezones for schedule execution.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: b88fc414-5d0a-4276-9546-3cdd63bff569

📥 Commits

Reviewing files that changed from the base of the PR and between 9b6a7ff and 7249a67.

📒 Files selected for processing (1)

• internal/service/scheduler/tick_planner.go

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📝 Walkthrough

Walkthrough

All schedule evaluation points in tick_planner.go are updated to use tp.cfg.Clock().In(tp.cfg.Location) or now.In(tp.cfg.Location) consistently. Previously, start schedules, one-off schedules, and catchup recomputation used raw clock time while stop/restart schedules already used the configured location.

Changes

Scheduler Location Consistency Fix

Layer / File(s)	Summary
Init and recomputeBuffer location normalization internal/service/scheduler/tick_planner.go	Init computes observedAt via tp.cfg.Clock().In(tp.cfg.Location) and recomputeBuffer computes its local now the same way, replacing raw clock references in both.
Plan: unified evalTime across all schedule types internal/service/scheduler/tick_planner.go	Plan introduces evalTime := now.In(tp.cfg.Location) and applies it to one-off readiness checks, cron scheduleDueAt calls, and stop/restart evaluation, removing the prior in-block re-localization in the stop/restart block.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main fix: applying the configured Location consistently across all schedule evaluations in the scheduler.
Description check	✅ Passed	The description comprehensively covers the problem, root cause, fix, and impact with clear detail and issue reference, though formal checklist items are absent.
Linked Issues check	✅ Passed	The PR fully addresses issue #2312 by applying configured Location consistently across all four schedule evaluation contexts (start, one-off, init reconciliation, and catchup).
Out of Scope Changes check	✅ Passed	All code changes in tick_planner.go are directly aligned with fixing the timezone asymmetry issue; no unrelated modifications are present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[yohamta0]

LGTM, thanks !