STUDYU-95: feat(app): complete Fitbit tasks offline

[johannesvedder]

Description

Related Jira issue: STUDYU-95

Stack 3 of 3 · Previous: #955

The deferred Fitbit engine from #955 must be connected to the visible participant flow. Participants also need durable Fitbit authorization before leaving the online kickoff so Fitbit tasks can be completed without connectivity.

This PR:

• requires durable Fitbit authorization during kickoff only for studies containing Fitbit questions;
• keeps participants in setup with retry when authorization is cancelled or storage fails;
• completes Fitbit questionnaire tasks locally while connectivity is degraded;
• queues the original Fitbit acquisition window instead of invoking immediate synchronization;
• keeps the normal online Fitbit path unchanged;
• resolves queued Fitbit data after reconnecting, including after the study has ended;
• handles calendar-day Fitbit acquisition windows without creating placeholder answers.

This completes the three-PR advanced offline participation stack built on #936.

Testing Steps

1. Start a Fitbit study online and verify kickoff cannot complete until authorization is durably stored.
2. Disconnect, complete ordinary, media, and Fitbit tasks, then reload while still offline.
3. Reconnect after the study ends and verify pending media, Fitbit data, and ordinary progress synchronize once.
4. Verify non-Fitbit studies and online Fitbit completion retain their existing behavior.
5. Automated verification completed:
   • 61 integrated recovery, cleanup, cache, offline-task, and Fitbit tests;
   • scripts/pre-commit-check;
   • git diff --check.

Manual Fitbit OAuth, token refresh/revocation, rate limits, and real multi-day sleep responses remain device/API verification items.

PR Checklist

• I tested the changes and affected user flows.
• I reviewed the full diff and checked for unintended changes.

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[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis ✅ 955 - PR Code Verified Compliant requirements: Connect deferred Fitbit completion to the participant questionnaire flow. Queue Fitbit completion while connectivity is degraded. Preserve the normal online Fitbit synchronization path. Require Fitbit authorization during kickoff for Fitbit studies. Requires further human verification: Verify historical acquisition after the study end date with real Fitbit data. Verify pending media ordering, retry behavior, and destructive-operation barriers across the complete stacked implementation. Verify OAuth cancellation, token refresh, revocation, rate limits, and multi-day sleep responses on real devices and APIs. 936 - PR Code Verified Compliant requirements: Preserve the existing offline task-completion integration by delegating deferred Fitbit completion through handleTaskCompletion. Requires further human verification: Verify the complete stacked cache-recovery, cleanup, authentication, and destructive-operation behavior from the earlier PRs. Verify offline completion and synchronization across ordinary, media, and Fitbit tasks in the participant UI.

⏱️ Estimated effort to review: 3 🔵🔵🔵⚪⚪

🏅 Score: 91

🧪 PR contains tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ No major issues detected

[github-actions]

Visit the preview URL for this PR (updated for commit 71c468b):

• https://studyu-dev-app--pr956-feat-studyu-906-offl-ncw2979v.web.app
• https://studyu-dev-designer--pr956-feat-studyu-906-offl-nossqyr4.web.app

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