OUT-4066: service-branch tests for sync error-shape edges

[SandipBajracharya]

What & why

Adds integration tests for the residual defensive / error-shape branches that a happy-path flow never hits — precise external-error handling, create-vs-update dead-ends, webhook controller guards, and resync-helper edges. Real Postgres + MSW, single service, no task orchestration. Test-only: no production changes.

Linear: OUT-4066

Coverage (10 new tests)

Dropbox create + quiet-delete (sync-error-shape.integration.test.ts, new)

• createAndUploadFileInDropbox dead-ends — existing item with an unexpected tag, and out-of-range file type — surface as a throw via completePendingDropboxCreate.
• deleteDropboxFileQuietly swallows a 409 path_lookup/not_found, rethrows any other error (→ markFailure + rethrow).
• deleteAssemblyFileQuietly swallows a Copilot 404, rethrows others.

Assembly webhook controller (+2)

• 800ms ping-pong guard runs before processing (asserted even on a skipped event).
• A create for an already soft-deleted file is skipped — the existingFile lookup intentionally omits the deletedAt IS NULL filter.

Resync sweep (+2)

• retryFailedSyncsForPortal returns early (no rows touched) when the portal has no Dropbox connection.
• An unrecognised (action, target) combo is caught per-row and recorded as a failure rather than aborting the sweep.

Harness

One shared change: the delete MSW mocks (mockDropboxDeleteFile / mockCopilotDeleteFile) now optionally return an error response (backward-compatible — existing callers pass no args).

Scoped out (per design)

Branches already covered by the flow tests (not_found→create, webhook status/eventType/create-gate/update/delete guards, resync per-row isolation). No extraction — these are I/O error branches tested through public entry points.

Testing

• pnpm typecheck ✅ · pnpm lint ✅ · pnpm test → 197 passed ✅
• pnpm test:integration → 141 passed ✅ (was 131; +10 new)

🤖 Generated with Claude Code

[linear-code]

OUT-4066

[vercel]

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Project	Deployment	Actions	Updated (UTC)
dropbox-integration	Ready	Preview	Aug 17, 2026 12:45pm

[greptile-apps]

Greptile Summary

Adds integration coverage for defensive synchronization branches without changing production code.

• Covers Dropbox and Copilot deletion error handling and create dead ends.
• Verifies webhook delay and soft-deleted-file guards.
• Exercises resync behavior for missing connections and unsupported action-target combinations.
• Extends MSW deletion helpers with optional error responses.

Confidence Score: 5/5

The PR appears safe to merge with no actionable defects identified.

The changes are test-only, and the new fixtures, mocks, seeded states, public entry points, and assertions align with the production branches they are intended to cover.

Important Files Changed

Filename	Overview
test/flows/assembly-webhook-controller.integration.test.ts	Adds correctly targeted coverage for the unconditional webhook delay and tombstoned-file create guard.
test/flows/resync-sweep.integration.test.ts	Adds deterministic coverage for missing-connection early return and per-row handling of an unsupported dispatch target.
test/flows/sync-error-shape.integration.test.ts	Adds integration tests that reach the intended create dead ends and distinguish swallowed not-found responses from rethrown deletion errors.
test/msw/write.ts	Extends existing delete mocks with backward-compatible optional error responses while retaining attempted-operation recording.

_{Reviews (1): Last reviewed commit: "test(OUT-4066): cover resync missing-con..." | Re-trigger Greptile}

[priosshrsth]

lgtm