feat(reader-core): add parser timeouts for EPUB content parsing

[d-oit]

Summary

• Adds withTimeout/checkDeadline/createDeadline utilities in @do-epub-studio/shared for parser timeout enforcement
• Integrates timeouts across all EPUB parsing entry points (archive validation, DOMPurify, OPF/XML, accessibility, reanchor)
• Forwards AbortSignal through epub-loader for proper cancellation
• Delegates worker-side validation to shared validateArchive (removes 78 lines of duplicated code)
• Adds 26 new tests across 3 test files

Motivation

Satisfies TIER-1 AGENTS.md requirement: "MUST apply parser timeouts to EPUB content parsing to prevent infinite loops on malformed input."

Default Timeout Budget

Operation	Default	Rationale
Archive validation	10s	CPU-bound, normal <1s
DOMPurify sanitize	5s	Per-chapter, normal <100ms
OPF/XML regex parsing	2s	Regex-only, normal <50ms
Accessibility parsing	2s	Regex-only, normal <50ms
Reanchor (all chapters)	15s	I/O-bound, normal <2s
Total load pipeline	30s	Existing worker-side timeout

Files Changed

• packages/shared/src/timeout.ts — new — core timeout utilities
• packages/shared/src/errors.ts — added TimeoutError class
• packages/shared/src/index.ts — barrel export
• packages/shared/src/__tests__/timeout.test.ts — new — 10 tests
• packages/reader-core/src/archive-validator.ts — timeout wrapper
• packages/reader-core/src/sanitizer.ts — deadline checks between DOMPurify passes
• packages/reader-core/src/fixed-layout.ts — deadline checks in OPF parsing
• packages/reader-core/src/epub-accessibility.ts — deadline checks in accessibility parsing
• packages/reader-core/src/epub-loader.ts — top-level withTimeout + signal forwarding
• packages/reader-core/src/reanchor.ts — deadline checks in reanchor loops
• packages/reader-core/src/epub-parser.worker.ts — delegated to shared validateArchive
• packages/reader-core/src/epub-parser-worker.ts — timeout options for fallback path
• packages/reader-core/src/__tests__/archive-validator-timeout.test.ts — new — 6 tests
• packages/reader-core/src/__tests__/sanitizer-timeout.test.ts — new — 5 tests

Test Results

All 1,840 tests pass across 7 packages. Quality gate (lint + typecheck) passes.

Design Decisions

• Synchronous checkDeadline() for sync code paths — DOMPurify and regex loops must remain synchronous for epubjs hook compatibility; uses performance.now() deadline checks every N iterations
• Async withTimeout() for async code paths — Uses AbortController/AbortSignal pattern for archive validation, reanchor, and top-level load pipeline
• All new parameters are optional — Full backward compatibility with existing callers

[cloudflare-workers-and-pages]

Deploying do-epub-studio with    Cloudflare Pages

Latest commit:	f6657ca
Status:	✅  Deploy successful!
Preview URL:	https://d4854f64.do-epub-studio.pages.dev
Branch Preview URL:	https://feat-parser-timeouts.do-epub-studio.pages.dev

View logs

[github-actions]

🚀 Performance Report

⚡ Startup & Interaction

Metric	Value (ms)	Limit (ms)	Trend	Status
First Contentful Paint	272.00	1500	-	✅
Chapter Switch Latency	0.00	300	-	✅
Offline Rehydrate Time	210.40	800	-	✅
DOM Interactive	37.50	-	-	-
Load Event End	190.80	-	-	-

🛠️ CI & Workflow

Metric	Value	Limit	Status
Total CI Duration	5.77 min	15.00 min	✅
Pnpm Cache Hit	Hit	-	✅

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

View in Codacy

🟢 Metrics 69 complexity · -14 duplication

Metric	Results
Complexity	69
Duplication	-14

View in Codacy

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