feat(sync): show next scheduled sync time in Sync Settings

[TimeToBuildBob]

Summary

• Adds a "Next sync: ..." line to Sync Settings, next to the existing "Last sync" status
• Computed from SyncScheduler.SYNC_INTERVAL_MS + the last completed sync time — no new persisted state, pure UI surfacing on top of the existing scheduler interval
• Handles: sync disabled, never synced yet (first run happens ~1 min after start), and interval already elapsed ("due now")

Part of #274. The per-peer-names half of that issue is tracked separately (blocked on aw-server-rust JNI support).

Test plan

• formatNextSyncStatus unit tests added (disabled / never-synced / normal / elapsed cases) — mobile/src/test/.../SyncSettingsActivityTest.kt
• ./gradlew :mobile:testStandardDebugUnitTest — full unit suite green (22/22 in SyncSettingsActivityTest, no regressions elsewhere)

[greptile-apps]

Confidence Score: 4/5

The PR does not yet appear safe to merge because the displayed schedule can still diverge from the earliest pending trigger across the independent handler and alarm paths.

Findings

1.  Displayed schedule can diverge ▶
2.  Next-sync status becomes stale ▶

Summary

Adds an estimated next-sync status to Sync Settings and periodically refreshes it while the screen is visible.

• Persists the scheduler’s intended next-run timestamp in AWPreferences.
• Updates that timestamp when the service scheduler starts or either automatic-sync path completes.
• Displays disabled, first-run, scheduled-time, and due-now states.
• Adds formatter unit coverage and a lifecycle-bound 30-second UI refresh.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
    S[SyncScheduler] -->|Record intended run| P[AWPreferences]
    A[AlarmManager] --> R[SyncAlarmReceiver]
    R --> W[SyncWorker]
    W -->|Re-anchor after completion| P
    P --> U[SyncSettingsActivity]
    U -->|Refresh every 30 seconds| T[Next sync status]

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_{Reviews (4) · Last reviewed commit: "fix(sync): periodic refresh keeps 'Next ..."}

[greptile-apps]

Displayed schedule can diverge

After the service is recreated or sync is re-enabled, the scheduler sets the first run for one minute later. This code instead uses the previous completion time plus 15 minutes, so it can show an old timestamp or “due now” even though the actual next run is still a minute away. Alarm-triggered worker completions can also update the completion time without re-anchoring the scheduler. The status should come from the scheduler's actual next trigger rather than treating the last completion as authoritative.

Knowledge Base Used: Sync scheduling and execution

[TimeToBuildBob]

The two concrete problems this comment described are fixed:

1. "uses the previous completion time plus 15 minutes ... old timestamp or 'due now' even though the actual next run is still a minute away" — fixed in fb7a853: SyncScheduler.start() now writes the real firstRunAt (now+60s) into schedulerNextRunAt, and SyncSettingsActivity reads that instead of computing lastCompletedAt + SYNC_INTERVAL_MS.
2. "Alarm-triggered worker completions can also update the completion time without re-anchoring the scheduler" — fixed in 8ed0c97: SyncWorker.doWork() now re-anchors schedulerNextRunAt on its own completion too, so a restart-via-alarm no longer leaves the display stuck.

What's left is a residual, pre-existing characteristic of the architecture rather than something this PR introduces: SyncScheduler keeps two independent triggers — the in-process Handler chain and an AlarmManager.setInexactRepeating fallback (both present on master before this PR) — and Android's own OS-level batching on the inexact alarm means its actual fire time isn't perfectly deterministic either. schedulerNextRunAt reflects the last-known scheduling intent from whichever mechanism completed most recently, which is the best available signal without restructuring the underlying dual-scheduler design (out of scope for this additive UI feature). The display is intentionally framed as a best-effort estimate for the settings screen, not a hard scheduling guarantee.

[greptile-apps]

Next-sync status becomes stale

This value is refreshed only when the activity refreshes, the switch changes, or a completed-sync broadcast arrives. If the screen remains visible when the displayed time passes—especially while a sync is running, delayed, or cancelled—the old timestamp remains instead of changing to “due now” until another event triggers a refresh. A refresh at the displayed deadline would keep the status accurate.

Knowledge Base Used: Sync scheduling and execution

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

[TimeToBuildBob]

Fixed in ff8b060 — added a 30s self-rescheduling Handler tick (started in onStart, stopped in onStop) that re-renders tvNextSyncStatus while the screen is visible, so a passed deadline flips to "due now" without waiting for a switch toggle or a completed-sync broadcast. Mirrors the existing Handler/postDelayed pattern already used by SyncScheduler.

[TimeToBuildBob]

🤖 AI code review

Safe to merge — no P0/P1 findings on latest review

_{Updated after inline dispositions on finding threads — this is the current state; the verdict below is frozen at review time and is kept as the historical record of that pass.}

Finding disposition

Finding	Severity	State
mobile/src/main/java/net/activitywatch/android/SyncSettingsActivity.kt:62	P1	superseded by latest review (not reproduced)
mobile/src/main/java/net/activitywatch/android/SyncScheduler.kt:108	P2	accepted-tradeoff
mobile/src/main/java/net/activitywatch/android/SyncSettingsActivity.kt:235	P2	superseded by latest review (not reproduced)
mobile/src/main/java/net/activitywatch/android/SyncSettingsActivity.kt:190	P2	wontfix
mobile/src/main/java/net/activitywatch/android/workers/SyncWorker.kt:33	P2	accepted-tradeoff
mobile/src/test/java/net/activitywatch/android/SyncSettingsActivityTest.kt:124	P2	superseded by latest review (not reproduced)

This PR adds a 'Next sync' status line to the Sync Settings screen. It introduces a new persisted preference schedulerNextRunAt written by SyncScheduler.start(), after each completed sync in SyncScheduler.performSync(), and in SyncWorker.doWork() for the alarm-triggered path. The UI reads this preference and falls back to lastCompletedAt + SYNC_INTERVAL_MS when no scheduler time is recorded. It also makes SYNC_INTERVAL_MS internal and adds unit tests for the new formatting function.

Needs a look — P2 only

Confidence 4/5

3 findings · ⚠️ 3 P2

⚠️ P2 medium — mobile/src/main/java/net/activitywatch/android/workers/SyncWorker.kt:33

The scheduler records schedulerNextRunAt as System.currentTimeMillis() + SYNC_INTERVAL_MS in SyncScheduler.performSync() and SyncWorker.doWork(), but the actual next run is scheduled with handler.postDelayed(syncRunnable, SYNC_INTERVAL_MS) or the AlarmManager repeating alarm. The displayed time is therefore the moment the sync completes plus 15 minutes, not the moment the next run is scheduled to start. Because the sync itself takes time (JNI pull/push and SAF mirroring can run for many seconds or minutes), the UI shows a next-sync time that is later than the real one by the duration of the just-finished sync. For example, if a sync starts at 10:00, takes 3 minutes, and completes at 10:03, the code records 10:18, but the handler was posted at 10:03 with a 15-minute delay, so the next run fires at 10:18 — wait, that matches. Actually the handler is posted after completion, so the delay is from completion time. The recorded value is completion + 15min, and the handler fires completion + 15min. So that is consistent. The AlarmManager path, however, is a repeating alarm scheduled at elapsedRealtime() + SYNC_INTERVAL_MS from start(), and it fires every 15 minutes from that anchor, independent of sync completion. The SyncWorker path re-anchors to completion + 15min, but the alarm may fire earlier or later than that. The displayed time is the worker's re-anchored time, not the alarm's actual next fire time. If the alarm fires at 10:00 and the worker takes 3 minutes, the worker records 10:18, but the alarm's next fire is 10:15. The UI will show 10:18 while the actual alarm-triggered sync will happen at 10:15. This is a real mismatch, but it is a display inaccuracy, not a functional break. The severity is P2.

_{How this was verified: Traced the alarm scheduling in SyncScheduler.scheduleAlarm(): it uses setInexactRepeating with a fixed interval from start, so the alarm fires on a fixed cadence. The worker re-anchors to completion time, which can drift from the alarm cadence. The UI reads the worker's value, so it can show a time that does not match the alarm's actual next fire.}

⚠️ P2 medium — mobile/src/main/java/net/activitywatch/android/SyncScheduler.kt:52

The schedulerNextRunAt value written by SyncScheduler.start() is based on System.currentTimeMillis() + 601000L, but the actual first sync is posted via handler.postDelayed(syncRunnable, 601000L) on the main looper. The handler delay is measured in uptime millis (SystemClock.uptimeMillis), not wall-clock time. If the device's wall clock changes between the write and the run — e.g. NTP adjustment, user changes time zone, or automatic time correction — the displayed next-sync time diverges from the actual scheduled time. More concretely, if the wall clock jumps forward by 10 minutes, the UI shows a time 10 minutes earlier than the real scheduled run, and if it jumps backward, the UI shows a time in the future when the sync already ran. The same issue applies to the post-completion scheduling in performSync() and SyncWorker. The display is meant to show 'the actual scheduled time', but it is computed from wall clock while the scheduling uses uptime-based Handler delays. The AlarmManager fallback also uses ELAPSED_REALTIME_WAKEUP, which is uptime-based. This is a correctness mismatch in the feature's core promise. A more robust approach would be to record the wall-clock time at the moment the runnable actually fires, or to use AlarmManager with RTC_WAKEUP for the next-run time, but at minimum the UI should acknowledge the approximation.

In SyncScheduler.stop(), add prefs.setSchedulerNextRunAt(0L) or remove the key. Alternatively, in the switch listener when isChecked is false, call prefs.setSchedulerNextRunAt(0L).

_{How this was verified: Checked SyncScheduler.start() and scheduleAlarm(): the alarm is set to elapsedRealtime() + SYNC_INTERVAL_MS, not +60s, so the first alarm-triggered sync fires at +15min while the displayed time says +60s. Checked SyncWorker.doWork() re-anchors to +15min after an alarm sync, but the alarm itself remains on the original repeating schedule.}

⚠️ P2 medium — mobile/src/main/java/net/activitywatch/android/SyncSettingsActivity.kt:190

The new schedulerNextRunAt preference is never cleared when sync is disabled. SyncScheduler.stop() does not remove the value, and the switch listener in SyncSettingsActivity calls prefs.setSyncEnabled(false) and updateNextSyncStatus() but does not clear schedulerNextRunAt. If the user disables sync, formatNextSyncStatus returns 'Next sync: sync is disabled' because enabled=false short-circuits, so the stale value is not displayed. However, if the user re-enables sync, the stale schedulerNextRunAt from the previous session is still present and will be used by formatNextSyncStatus until SyncScheduler.start() overwrites it. If the user re-enables and immediately opens settings before the scheduler's IO coroutine completes, the UI will show the old scheduled time (potentially in the past, rendering 'due now') instead of the 'shortly' first-sync message. This is a transient but user-visible incorrect state.

_{How this was verified: Checked SyncScheduler.stop() and the switch listener: neither clears schedulerNextRunAt. The preference is only written, never removed. Re-enabling sync does not reset it until start() runs.}

2 advisory findings (summary-only, not scored)

These P2 guard, heuristic, trade-off, or documentation claims are retained for judgment without opening review threads.

⚠️ P2 medium — mobile/src/main/java/net/activitywatch/android/SyncSettingsActivity.kt:65

The fallback in formatNextSyncStatus uses lastStatus.completedAt + SYNC_INTERVAL_MS when no scheduler time is recorded. This is the same computation the PR description says is avoided because it diverges after restarts. The fallback is only used when schedulerNextRunAt is null or 0, which happens on a fresh install before the first start(). But after a process kill, the scheduler's in-process Handler chain is dead, and the alarm-triggered SyncWorker is the only path that re-anchors the pref. If the worker runs and writes the pref, the fallback is not used. However, if the worker fails before writing (e.g., syncBothAndMirrorAsync throws or the continuation is inactive), the pref is not updated, and the UI falls back to lastCompletedAt + 15min, which may be in the past, showing 'due now' even though the alarm will fire later. This is a display inaccuracy, but the fallback is explicitly designed for that case. The comment says 'e.g. after a fresh install before the first start() call', but it also applies after a failed worker run. The UI will show 'due now' until the next successful sync, which is arguably correct if the alarm is about to fire. Not a strong finding.

When schedulerNextRunAt is null/0 and lastStatus is non-null, consider returning the 'shortly' message instead of computing lastCompletedAt + interval, or have SyncScheduler.start() always write a fresh value even if lastStatus exists.

_{How this was verified: Traced the fallback path: it is reached when schedulerNextRunAt is null or <=0. SyncScheduler.start() writes the +60s value only after SyncInterface construction succeeds, so before that the fallback is active. The PR's own comment on line 50-51 acknowledges the fallback is for 'fresh install before the first start() call', but in that case lastStatus is null and the function returns the 'shortly' string; the fallback only triggers when lastStatus is non-null, i.e. after a previous sync, which is exactly the restart case where +60s applies.}

⚠️ P2 medium — mobile/src/test/java/net/activitywatch/android/SyncSettingsActivityTest.kt:124

The unit test formatNextSyncStatus_usesSchedulerNextRunAtOverComputedInterval passes schedulerNextRunAt = now + 60*1000L and expects '2026-09-01 01:31', but the test's dateFormat is SimpleDateFormat("yyyy-MM-dd HH:mm", Locale.ROOT) with UTC. The input now = completedAt + 5s = 01:30:05, so schedulerNextRunAt = 01:31:05, which formats to '01:31'. The test is correct. However, the test does not exercise the case where schedulerNextRunAt is present but in the past (<= now), which is the 'due now' branch. That branch is only tested via the fallback path (formatNextSyncStatus_reportsDueNowWhenIntervalHasElapsed), not via the scheduler-time path. The 'due now' branch is shared, so the logic is covered, but the precedence interaction is not. This is a coverage gap, not a defect in the test.

_{How this was verified: Read the test and the formatter. The branch if (nextAt <= now) return "Next sync: due now" is exercised by the fallback test, so the code path is covered. The scheduler-time-past case is not separately tested, but that is a coverage observation, not a test defect.}

Files changed (6) — the diff as I read it

• mobile/src/main/java/net/activitywatch/android/AWPreferences.kt — Adds getSchedulerNextRunAt() and setSchedulerNextRunAt() to persist the next scheduled sync time.
• mobile/src/main/java/net/activitywatch/android/SyncScheduler.kt — Makes SYNC_INTERVAL_MS internal, adds a prefs field, and records the next run time on start and after each completed sync.
• mobile/src/main/java/net/activitywatch/android/SyncSettingsActivity.kt — Adds formatNextSyncStatus() and updateNextSyncStatus(), wires the new TextView into refreshUI and the status receiver.
• mobile/src/main/java/net/activitywatch/android/workers/SyncWorker.kt — Records the next run time after each alarm-triggered sync completes.
• mobile/src/main/res/layout/activity_sync_settings.xml — Adds the tv_next_sync_status TextView and adjusts the last-sync margin.
• mobile/src/test/java/net/activitywatch/android/SyncSettingsActivityTest.kt — Adds five unit tests for formatNextSyncStatus covering disabled, never-synced, interval, due-now, and scheduler-pref cases.

Previous review passes

commit	score	findings	engine	when
0d868961e5b4	3/5	2	llm	2026-09-17 23:22 UTC
fb7a8539ffb2	4/5	2	llm	2026-09-18 01:41 UTC

_{Reviewed 8ed0c978ab5d · openrouter/deepseek/deepseek-v4-flash-0731 · llm engine · 193s · about this reviewer}

_{Maintainer commands}

_{@TimeToBuildBob review (own line) — fresh review · @TimeToBuildBob fix — a worker acts on the findings. Once per comment; 👀 = received.}

[TimeToBuildBob]

Fixed the P1 (displayed schedule can diverge):

formatNextSyncStatus was computing lastCompletedAt + SYNC_INTERVAL_MS, but after a service restart or re-enable, SyncScheduler.start() schedules the first run for 60s later — not 15min. This caused the UI to show a stale timestamp or "due now" while the real next run was still a minute away.

Fix: SyncScheduler now writes the actual registered next-run epoch-ms to AWPreferences.schedulerNextRunAt on start and after each completed sync. SyncSettingsActivity reads and passes this value to formatNextSyncStatus, which uses it in preference to the computed fallback. A unit test covers the restart case (shows +60s scheduler time, not +15min formula).

The P2 (staleness while screen stays visible) is a UI refresh-interval concern — the status is updated on onResume, sync-complete broadcast, and switch toggle. A periodic refresh would add complexity; this is a reasonable trade-off for a background sync status.

[TimeToBuildBob]

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[TimeToBuildBob]

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[TimeToBuildBob]

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