OUT-4083: cover untested error and guard branches in sync + webhook

[SandipBajracharya]

What & why

A coverage pass found a few defensive branches the existing tests never reached. This adds integration tests for them. Test-only — no production changes, and it fits the existing harness.

Linear: OUT-4083

Coverage (9 new tests)

Sync.service create / root-path guards

• Assembly → Dropbox create returns the existing folder's id without re-uploading when the folder already exists.
• handleChannelMap records the Dropbox root folder id for a valid folder, and rejects a non-folder root path with a 400.
• The leaf create stamps the Assembly file id before uploading, so a "file created" echo dedupes against the row (asserted by reading the row at upload time).

Channel map

• updateChannelMap only updates when the root path matches exactly; a moved/stale root path matches nothing and leaves the row unchanged.

Webhook debounce + fetch

• handleDropboxEvents skips an account with no active connection (asserts the sync is never triggered), and skips when a webhook is already pending even past the debounce window.
• fetchDropBoxChanges returns early when the connection is missing or has no refresh token.

Notes

• Each test targets the exact branch: the "existing folder" and "not-a-folder" tests register no move/upload mocks, so a stray call trips onUnhandledRequest:'error'; the stamp-before-upload and no-active-connection tests use call-time reads / trigger spies so they fail if the guard regresses.

Testing

• pnpm typecheck ✅ · pnpm lint ✅ · pnpm test → 192 passed ✅
• pnpm test:integration → 179 passed ✅ (was 170; +9)

🤖 Generated with Claude Code

[linear-code]

OUT-4083

[vercel]

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Project	Deployment	Actions	Updated (UTC)
dropbox-integration	Ready	Preview	Aug 20, 2026 1:11pm

[greptile-apps]

Greptile Summary

This test-only PR expands integration coverage for defensive sync, channel-map, and Dropbox webhook behavior.

• Verifies exact root-path matching, root-folder validation, and existing-folder handling.
• Verifies Assembly file IDs are persisted before content upload.
• Covers inactive, pending, missing-connection, and missing-refresh-token webhook guards.
• Adds assertions for error propagation and cleanup behavior in synchronization flows.

Confidence Score: 5/5

The PR appears safe to merge because it only adds focused integration tests and no actionable defects were identified.

The added fixtures, mocks, and assertions reach the intended production guard and ordering branches while remaining consistent with the repository’s test isolation and request-handler conventions.

Important Files Changed

Filename	Overview
test/flows/channel-map-resync-guards.integration.test.ts	Adds deterministic database-backed coverage for exact channel-map path matching alongside connection and resync cleanup guards.
test/flows/dropbox-to-assembly.initial-sync.integration.test.ts	Adds an MSW-backed ordering test confirming the Assembly file ID is persisted before the upload request occurs.
test/flows/dropbox-webhook-debounce.integration.test.ts	Adds isolated coverage for inactive connections and already-pending webhook events without changing production behavior.
test/flows/dropbox-webhook-internals.integration.test.ts	Adds early-return coverage for missing or unusable Dropbox connections.
test/flows/sync-error-shape.integration.test.ts	Adds coverage for existing-folder reuse and Dropbox root-path folder validation.

_{Reviews (1): Last reviewed commit: "test(OUT-4083): cover webhook debounce +..." | Re-trigger Greptile}

[priosshrsth]

Lgtm