🛡️ Sentinel: [MEDIUM] CSP Hash 적용 방식 보안 강화

[seonghobae]

🚨 Severity: MEDIUM
💡 Vulnerability: 정적 리소스용 CSP 생성 시 해시 불일치
🎯 Impact: 브라우저가 스타일을 차단하여 화면이 깨지거나 CSP 우회가 가능해짐
🔧 Fix: <style> 태그 내부 내용을 정확하게 맞추기 위해 trimIndent()를 사용하고 공백 없이 주입함
✅ Verification: ./gradlew test 통과 및 생성된 HTML 내의 스타일과 해시가 정확히 일치함

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PR created automatically by Jules for task 12596847652619187529 started by @seonghobae

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[Copilot]

Pull request overview

This PR hardens html4tree’s generated index.html Content Security Policy (CSP) by ensuring the style-src SHA-256 hash is computed from the exact inline <style> content that is emitted into the HTML, preventing browser style blocking and avoiding hash/markup mismatches.

Changes:

• Normalize the CSS multiline string with trimIndent() and compute the CSP sha256-... hash from that normalized value.
• Emit the <style> tag as a single string (<style>${content}</style>) to avoid template-introduced whitespace differences.
• Document the CSP hash mismatch lesson/prevention guidance in the Jules Sentinel log.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/main/kotlin/html4tree/main.kt	Aligns CSP hash input with emitted <style> text by normalizing and injecting the exact same string.
.jules/sentinel.md	Records the security learning/prevention note related to CSP hash mismatches from multiline string injection.

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[seonghobae]

Closing as superseded by canonical #363. Both repair the inline-style CSP hash mismatch, but #363 additionally verifies the exact emitted UTF-8 style bytes from a real generated page, hoists the immutable source and hash, adds APA 7 doctoring and changelog, and has fresh current-head CI/JaCoCo/Security/Semgrep evidence. No result from this duplicate head is reused.

[google-labs-jules]

Closing as superseded by canonical #363. Both repair the inline-style CSP hash mismatch, but #363 additionally verifies the exact emitted UTF-8 style bytes from a real generated page, hoists the immutable source and hash, adds APA 7 doctoring and changelog, and has fresh current-head CI/JaCoCo/Security/Semgrep evidence. No result from this duplicate head is reused.

Understood. Acknowledging that this work is now obsolete and superseded by canonical #363, and stopping work on this task.