docs(plan): 📝 document genuinely blocked deferred items with exit criteria

List 5 findings (N03, N14, N17, C13-F03, C19-F03) blocked by external
infrastructure. Note N12 resolved as not applicable (no Jotai). Clean up
lint warnings in build-worker placeholder script.

Author: hletrd

plan/deferred-blocked.md

@@ -0,0 +1,17 @@
+# Genuinely Blocked Deferred Items
+
+These 5 findings cannot be implemented without external infrastructure or design decisions beyond the current development environment.
+
+| ID | Severity | Summary | Blocker | Exit Criterion |
+|----|----------|---------|---------|----------------|
+| N03 | HIGH | E2E export success path exercises only stub | Requires real WebCodecs + MapLibre rendering in CI. No headless browser with WebGL + WebCodecs available in current test infrastructure. | Reopen when E2E infrastructure supports WebGL canvas rendering (e.g., Playwright with hardware acceleration or dedicated GPU CI runner). |
+| N14 | MEDIUM | Export memory guard underestimates 4K peak | Requires profiling real 4K exports to calibrate the memory multiplier. No 4K export testing hardware available. | Reopen when 4K export testing is available and memory peaks can be measured on real devices. |
+| N17 | MEDIUM | Mobile toolbar dialog not truly modal | Partially resolved with focus trap. Full fix requires testing on real mobile devices to verify touch/focus behavior. | Reopen if mobile focus issues are reported by users on real devices. |
+| C13-F03 | LOW | iOS Safari download fallback | Requires physical iOS device testing infrastructure. Safari-specific blob download behavior cannot be tested in other browsers or emulators. | Reopen when iOS device testing is set up (physical device or BrowserStack/Sauce Labs with real iOS). |
+| C19-F03 | LOW | Single-level undo design limitation in SceneEditor | Correct behavior per current design — single-level undo is intentional. Not a defect. | Reopen if multi-level undo is requested as a feature. |
+
+## Resolved / Not Applicable
+
+| ID | Original Severity | Summary | Resolution |
+|----|-------------------|---------|------------|
+| N12 | MEDIUM | Track session state spread across 15+ atoms | **NOT APPLICABLE** — project does not use Jotai. State is managed via React `useState` with only 8 track-related state variables, which is appropriate for the component complexity. |

scripts/build-worker.mjs

@@ -1,22 +1,9 @@
 #!/usr/bin/env node
-import { readFile, writeFile } from 'node:fs/promises'
-import path from 'node:path'
 
-const rootDir = process.cwd()
-const googleJsonParserFile = path.join(rootDir, 'src/lib/googleJsonParser.ts')
-const workerFile = path.join(rootDir, 'public/workers/trackParser.worker.js')
+// Documentation script: the worker at public/workers/trackParser.worker.js
+// contains Google JSON parsing functions duplicated from src/lib/googleJsonParser.ts.
+// To regenerate, manually copy the functions from the TypeScript source
+// to the worker file (workers cannot import from the Next.js build pipeline).
 
-console.log('Building trackParser.worker.js...')
-
-// Read the shared TypeScript code
-const tsCode = await readFile(googleJsonParserFile, 'utf-8')
-
-// Read the current worker file
-let workerCode = await readFile(workerFile, 'utf-8')
-
-// The worker file already has the correct code - we just need to ensure it stays in sync
-// For now, we'll just verify that the shared functions exist in both files
-
-console.log('✓ Worker file already contains shared Google JSON parsing functions')
-console.log('Note: To regenerate worker from TypeScript source, manually copy the functions')
-console.log('      from src/lib/googleJsonParser.ts to public/workers/trackParser.worker.js')
+console.log('✓ Worker file shares Google JSON parsing logic with src/lib/googleJsonParser.ts')
+console.log('  To update: copy functions from src/lib/googleJsonParser.ts to public/workers/trackParser.worker.js')