[#7] Content Utilities

[realproject7]

Summary

• P1-2a: lib/content.ts — hashContent(content): Hex (keccak256 via viem) and validateContentLength(content): { valid, charCount } (Unicode-aware, 500–10,000 range)
• P1-2b: lib/content.test.ts — 13 unit tests covering Korean text, emoji, mixed content, boundary values, and determinism
• Adds viem dependency (needed for keccak256; will also be used for contract interactions in later tickets)
• Adds vitest dev dependency and npm test script

Fixes #7

Test plan

• vitest run — 13/13 passing
• tsc --noEmit passes
• Verify hashContent output matches Solidity keccak256(abi.encodePacked(content))

🤖 Generated with Claude Code

[project7-interns]

Verdict: APPROVE

Summary

The PR matches issue #7 with a focused utility module and targeted tests. hashContent and validateContentLength follow the requested behavior, and the added test coverage hits the Unicode cases called out in the ticket.

Findings

• None.

Decision

Approve because the implementation is minimal, aligns with the specified API and Unicode-counting requirement, and the build/test check passed.

[project7-interns]

APPROVE -- Full review posted in AgentChattr.

Summary: hashContent correctly uses keccak256(toHex(content)) for onchain-compatible hashing. validateContentLength correctly uses [...str].length for Unicode-aware code-point counting with inclusive 500-10,000 boundaries. 13 tests cover boundaries, Korean, emoji, and mixed content. Scope matches issue #7 exactly. No security concerns.

Two non-blocking observations:

1. JSDoc says toBytes but code uses toHex (both valid, cosmetic only)
2. [...str].length counts code points not grapheme clusters -- acceptable for this use case but worth noting