Integration: Microsoft To Do

[desimpson]

Parent tracker: #64
Phase: 1
Complexity: L1

User Value

Users on Microsoft 365 can process To Do tasks from a single Syncer inbox in Obsidian without manually copying items between systems.

In Scope

• Connect/disconnect Microsoft To Do account(s) from Syncer.
• Let users choose which To Do lists are included in sync.
• Surface synced To Do items in the configured Syncer target location with source attribution and working links.
• Define clear completion and removal behavior consistent with the shared integration contract.

Out of Scope

• Implementation design and technical architecture details.
• Non-To Do Microsoft integrations and unrelated refactors.

Sync Model and Directionality

• Sync model: periodic pull
• Directionality: bidirectional for completion where supported; document any exceptions

Identity Strategy

Canonical identity target: {source, externalItemId} using stable To Do task IDs. Document fallback only if provider constraints require it.

Acceptance Criteria

• User can connect and disconnect the account and see current connection state.
• User can choose which provider content is included in sync.
• Included items appear in the configured Syncer destination with source attribution and valid links.
• Completion behavior is explicitly defined and behaves consistently with Syncer expectations for this integration.
• Deselection/removal behavior is explicitly defined and user-safe (no surprise destructive behavior).
• Disabling or disconnecting the integration does not corrupt existing Syncer state or create duplicates.
• Error handling is actionable and categorized for authentication/authorization failure, provider sync/read failure, and provider limitation/constraint.
• Release note and documentation updates required for this integration are identified.

AC Testability Checks

• Every AC is verifiable via UI observation or an observable product state change.
• No AC requires logs, console output, or developer tooling to validate.
• AC statements avoid implementation language.

Open Questions

Blocking:

• What is the user-visible completion behavior when a task is completed in To Do outside Obsidian?

Non-blocking:

• Should initial rollout support list selection only before advanced filters?

Dependencies / Follow-ups

• Multi-account support as a cross-cutting capability.
• Per-source target heading support for better multi-integration workflows.
• Any overlap with other integrations must be explicitly justified in the parent tracker.

Implementation-Readiness Gate

Mark this issue ready only when:

• Contract alignment is explicit (identity, lifecycle, directionality, sync model).
• Scope boundaries are clear.
• Blocking question(s) are resolved.
• Phase and complexity tier are assigned.

[desimpson]

Locked product decisions (implementation starting)

External completion semantics — mirroring Google Tasks:

• Incoming feed is incomplete tasks only from selected lists.
• Completing a task in Microsoft To Do removes it from the feed → the unchecked Obsidian line is removed on the next sync.
• [x] lines are preserved via shouldPreserveCompletedDeletes.
• With syncCompletionStatus enabled, unchecking in Obsidian can restore a To Do-completed task (job also fetches completed tasks to build taskId → listId for PATCH).

Accepted UX tradeoff: Syncer does not flip the checkbox to [x] when a task is completed remotely. The line disappears instead. This matches the Google Tasks incomplete-feed model and is deliberate — not an accidental omission.

Other locked choices: separate microsoftToDo credentials (Tasks scopes, not shared with Outlook mail token); list selection only; deep links via unofficial to-do.live.com / to-do.office.com patterns with list-level fallback; 429 → notice + abort (no in-job retry/sleep).

[desimpson]

PR + test evidence

PR: #122 (Closes #54)

Automated

• npm test: all suites passed (286+ tests; includes To Do unit tests + reconcile file-wide identity regression)

Manual (dev vault)

• Connect / list select / sync incomplete To Do tasks under heading with source: microsoft-to-do
• Completion write-back with Sync completion status on (Obsidian check → Graph PATCH 200 → completed in To Do)
• Kanban column moves + re-sync no longer recreate duplicates after file-wide reconcile fix
• Auth-expired modal names Syncer + Microsoft To Do

Still for merge checklist

• Sequential Outlook vs To Do account-kind switch; To Do disconnect leaves Outlook alone
• Confirm Entra app has delegated Tasks.ReadWrite on the existing Syncer client ID