docs: add TODO for remaining test coverage gaps

Document areas that still need test coverage improvement,
prioritized by impact and risk.

https://claude.ai/code/session_01WbLkUVQ5yi1bnSvGZErC3C

issues/todo-test-coverage-gaps.md

@@ -0,0 +1,123 @@
+# TODO: Improve Test Coverage for Untested Areas
+
+**Source:** Test coverage analysis (Feb 2026)
+
+**Context:**
+Several areas of the codebase lack unit test coverage. This document tracks the remaining gaps after the initial test coverage expansion.
+
+---
+
+## High Priority
+
+### Storage Layer
+Files with no tests that handle critical upload/storage functionality:
+
+- [ ] `js/storage/s3-multipart.js` - Multipart upload logic, bucket management
+- [ ] `js/storage/s3-client.js` - S3 client wrapper, SDK loading
+- [ ] `js/storage/r2-mgmt.js` - R2 bucket management operations
+- [ ] `js/storage/r2-s3.js` - R2/S3 integration layer
+- [ ] `js/services/s3UploadService.js` - Upload orchestration and progress tracking
+
+**Why:** These are user-facing upload paths. Failures here directly impact content creators.
+
+---
+
+## Medium Priority
+
+### DM Components
+The `js/ui/dm/` directory lacks unit tests:
+
+- [ ] `ConversationList.js` - Conversation list rendering
+- [ ] `MessageThread.js` - Message thread display
+- [ ] `MessageBubble.js` - Individual message rendering
+- [ ] `Composer.js` - Message composition UI
+- [ ] `ZapInterface.js` - Zap sending interface
+- [ ] `NotificationCenter.js` - DM notification handling
+- [ ] `Avatar.js` - Profile avatar display
+- [ ] `ContactRow.js` - Contact list item
+- [ ] `DMPrivacySettings.js` - Privacy settings UI
+- [ ] `AppShell.js` - DM app shell layout
+
+**Why:** Growing feature area with complex state management.
+
+### Video Utilities
+- [ ] `js/utils/videoTimestamps.js` - Timestamp parsing and formatting
+- [ ] `js/utils/videoPointer.js` - Video pointer utilities
+- [ ] `js/utils/torrentHash.js` - Torrent hash utilities
+
+**Why:** Core video functionality used throughout the app.
+
+---
+
+## Low-Medium Priority
+
+### Kids Mode Features
+Safety-critical filtering that should have thorough test coverage:
+
+- [ ] `js/feedEngine/kidsAudienceFilterStage.js` - Kids mode content filtering
+- [ ] `js/feedEngine/kidsScoring.js` - Kids-appropriate content scoring
+
+**Why:** Safety-critical filtering for younger audiences.
+
+### Application Bootstrap
+- [ ] `js/app.js` - Main application orchestrator
+- [ ] `js/bootstrap.js` - Application initialization
+- [ ] `js/applicationContext.js` - Application context management
+
+**Why:** Complex initialization logic that's difficult to test but important for reliability.
+
+---
+
+## Low Priority
+
+### Miscellaneous Utilities
+- [ ] `js/utils/domUtils.js` - DOM helper functions
+- [ ] `js/utils/hex.js` - Hex encoding utilities
+- [ ] `js/utils/qrcode.js` - QR code generation
+- [ ] `js/utils/linkPreviewSettings.js` - Link preview configuration
+- [ ] `js/utils/storage.js` - Local storage utilities
+- [ ] `js/utils/storagePointer.js` - Storage pointer helpers
+- [ ] `js/utils/profileMedia.js` - Profile media handling
+
+### UI Components
+- [ ] `js/ui/ModalManager.js` - Modal lifecycle management
+- [ ] `js/ui/initEditModal.js` - Edit modal initialization
+- [ ] `js/ui/initDeleteModal.js` - Delete modal initialization
+- [ ] `js/ui/watchHistoryController.js` - Watch history UI
+- [ ] `js/ui/profileIdentityController.js` - Profile identity display
+- [ ] `js/ui/ambientBackground.js` - Ambient background effects
+- [ ] `js/ui/components/DeleteModal.js` - Delete confirmation modal
+- [ ] `js/ui/components/FeedInfoPopover.js` - Feed information popover
+- [ ] `js/ui/components/EventDetailsModal.js` - Event details display
+- [ ] `js/ui/components/EmbedVideoModal.js` - Video embed modal
+
+### Nostr Internals
+- [ ] `js/nostr/dmDecryptWorker.js` - DM decryption web worker
+- [ ] `js/nostr/dmDecryptWorkerClient.js` - Worker client interface
+- [ ] `js/nostr/nip04Worker.js` - NIP-04 web worker
+- [ ] `js/nostr/nip04WorkerClient.js` - NIP-04 worker client
+- [ ] `js/nostr/countDiagnostics.js` - Count query diagnostics
+- [ ] `js/nostr/maxListenerDiagnostics.js` - Event listener diagnostics
+
+---
+
+## E2E Test Gaps
+
+Only 6 E2E tests exist. Consider adding:
+
+- [ ] Full upload flow (video file -> published note)
+- [ ] Video playback fallback scenarios (URL -> magnet)
+- [ ] Authentication flows (NIP-07, NIP-46 connection)
+- [ ] Relay switching behavior under failure conditions
+- [ ] Watch history persistence and sync
+- [ ] DM conversation flow
+
+---
+
+## Notes
+
+- When adding tests, follow existing patterns in `tests/` directory
+- Use `node:test` and `node:assert/strict` for unit tests
+- Use Playwright for E2E tests
+- Mock external dependencies (nostr-tools, relays) appropriately
+- Run `npm run test:unit` to verify new tests pass