⚡ Bolt: CSS 해시 및 문자열 할당을 Top-level로 추출하여 성능 최적화

[seonghobae]

💡 What: process_dir 함수 내에서 매 디렉토리 순회마다 수행되던 SHA-256 연산과 긴 CSS 문자열 할당을 파일 최상위 레벨로 이동하여 단 한 번만 초기화되도록 수정했습니다.
🎯 Why: 디렉토리 트리가 깊거나 파일이 많은 경우, 동일한 고정 CSS 문자열을 반복해서 메모리에 할당하고 무거운 암호화 해시 연산(MessageDigest.getInstance("SHA-256").digest(...))을 매번 수행하는 것은 심각한 CPU 및 메모리 낭비를 초래하는 성능 병목이었습니다.
📊 Impact: 디렉토리 개수에 비례하던 불필요한 메모리 할당 및 해시 연산 오버헤드를 O(N)에서 O(1)로 줄여, 파일 트리가 클수록 생성 속도가 크게 단축됩니다.
🔬 Measurement: ./gradlew test jacocoTestReport를 통해 100% 테스트 커버리지가 유지되는지(특히 암묵적 getter 테스트 추가)와 기존 생성 로직이 깨지지 않았는지 확인했습니다.

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PR created automatically by Jules for task 3767992703028400518 started by @seonghobae

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[Copilot]

Pull request overview

This PR optimizes the html4tree Kotlin CLI by hoisting the per-directory inline CSS string and its SHA-256 CSP hash computation out of process_dir into top-level properties so they are initialized only once per process run.

Changes:

• Move the fixed inline CSS (cssContent), CSP style hash (styleHash), and <style> block (css) from inside process_dir to top-level properties.
• Add a unit test intended to exercise the new top-level properties to preserve JaCoCo coverage.
• Add a new performance-learning entry to .jules/bolt.md.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
src/main/kotlin/html4tree/main.kt	Hoists CSS string + SHA-256 CSP hash to top-level to avoid repeated per-directory allocation/hash work.
src/test/kotlin/html4tree/MainTest.kt	Adds coverage for the newly introduced top-level properties.
.jules/bolt.md	Documents the performance optimization as a “Bolt” learning entry.

Comments suppressed due to low confidence (1)

src/test/kotlin/html4tree/MainTest.kt:717

• assertNotNull(...) on non-nullable top-level vals is redundant and doesn’t validate that the CSP hash actually matches the inline style content. This test can be stronger (and still hit the getters for coverage) by asserting the expected SHA-256/Base64 hash for cssContent.

        assertNotNull(styleHash)
        assertNotNull(css)
        assertTrue(styleHash.startsWith("sha256-"))
        assertTrue(css.contains(cssContent))
    }

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