Formulus: per-profile auto-sync (foreground, silent) #916

Summary

Add an auto-sync option to Formulus profile settings, so the active profile can periodically sync while Formulus is in the foreground, without noisy failure UX.

Depends on: Formulus multi-profile / multiple Synkronus settings support (same idea as ODE Desktop profiles) already being implemented. Do not start this until that lands.

Out of scope: ODE Desktop — Formulus only for now. No background/OS-scheduled sync in this issue.

Settings UI (profile page)

• Toggle (slider) to enable auto-sync — default off.
• When the toggle is on, reveal a panel with:
  • Interval dropdown
  • Status indicator (dot + label) — see below
  • Short copy that auto-sync runs only while Formulus is active/foregrounded (e.g. while using the app / filling forms), not when backgrounded or killed
• When the toggle is off, hide that panel (interval control not shown; treat as disabled).
• Interval dropdown values: 30s, 2m, 5m, 15m, 1h, 24h — default 5m.
• Interval control is only meaningful when auto-sync is on (lives in the revealed panel).

Scheduling

• Foreground only: timer/logic active while the app is active; no background sync for this feature.
• Interval measured from last successful sync.
• On enable, app resume, or coming online: wait for the next interval (do not fire immediately).
• Active profile only — do not auto-sync inactive profiles even if they have the setting on.
• Profile switch: cancel any in-flight auto-sync, then switch.
• Debounce / locking: do not queue auto-sync. If a sync is already running (auto or manual), skip the scheduled tick. Share one sync lock with manual sync and the custom-app bridge sync().
• If the user starts a manual sync, cancel an in-flight auto-sync; manual sync keeps today’s error/toast behavior.
• Auto-sync itself is silent on failure (no “sync failed” pop-ups).

Sync scope

• Same pipeline as manual sync except omit app-bundle update.
• Silent: do not drive the Sync screen / intrusive progress UI; profile status indicator is enough. For detail, user runs manual sync.

Connectivity & status indicator

Coloured dot on the profile UI (with label):

Relative time format: rounded integer + unit — minutes / hours / days / months ago (e.g. 5 minutes ago, 2 hours ago).

Form entry concurrency

Allow auto-sync while Formplayer / forms are open unless implementation finds clear drawbacks (e.g. observation write contention with in-progress drafts). If conflicts appear, pause auto-sync during active form sessions and document that in the PR.

Acceptance criteria

• Blocked until Formulus profiles exist; settings are per profile.
• Toggle + conditional panel (interval, status, foreground-only note); defaults: off, interval 5m.
• Intervals: 30s, 2m, 5m, 15m, 1h, 24h.
• Foreground-only; schedule from last successful sync; no immediate sync on enable/resume/online.
• Active profile only; cancel auto-sync on profile switch.
• Shared non-queueing lock with manual sync and bridge sync(); manual cancels auto; auto skips if busy.
• Auto-sync silent; manual sync errors unchanged; no app-bundle step in auto-sync.
• Status dots/labels as specified (green / blink / red Offline vs Connection failed / amber failure / Login failed / gray off).
• Formulus only — not Desktop.

Implementation notes

• Reuse existing sync services / progress where practical, but keep auto-sync UX on the profile panel.
• Prefer device connectivity plus /health for the red label split.
• Watch battery/CPU on 30s interval while foregrounded; no background work in v1.