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⚡ Bolt: [성능 개선] String.format 기반 16진수 변환을 HexFormat으로 대체 #66

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⚡ Bolt: [성능 개선] String.format 기반 16진수 변환을 HexFormat으로 대체 #66

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3 changes: 3 additions & 0 deletions .jules/bolt.md
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## 2024-06-30 - Hex Format Optimization

@opencode-agent opencode-agent Bot Jun 30, 2026

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HIGH OpenCode could not establish approval sufficiency

  • Problem: the model pool exhausted without a valid current-head review control block, so this changed line cannot be approved from deterministic check state alone.
  • Impact: PR-intent mismatches, missing files, robustness bugs, UX/DX regressions, and CodeGraph-backed flow changes could be missed.
  • Fix: rerun OpenCode after model availability recovers, or add the missing source/test/docs/generated verification evidence needed for a source-backed approval.
  • Verification: rerun the OpenCode Review workflow and confirm it emits APPROVE or source-backed REQUEST_CHANGES for this head SHA.

**Learning:** Using String.format() in a loop to convert byte arrays to hex strings allocates many temporary objects (String, Object[] for varargs) and performs poorly. The application's DefaultDocumentConversionService previously used this pattern for hashing uploads, impacting memory and CPU heavily.
**Action:** Always prefer java.util.HexFormat.of().formatHex(bytes) introduced in Java 17 for byte-to-hex conversion to improve performance, minimize object allocation, and make the code cleaner.
8 changes: 2 additions & 6 deletions src/main/java/com/clearfolio/viewer/service/DefaultDocumentConversionService.java
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import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.HexFormat;

import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;
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}

byte[] raw = digest.digest();
StringBuilder hex = new StringBuilder(raw.length * 2);
for (byte b : raw) {
hex.append(String.format("%02x", b));
}

return hex.toString();
return HexFormat.of().formatHex(raw);
} catch (NoSuchAlgorithmException ex) {
throw new IllegalStateException("SHA-256 digest unavailable", ex);
} catch (IOException ex) {
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