fix: smart_edit — add required output field + Claude-style diff formatting + normalization typo

[four-bytes-robby]

Bugs Found

1. Missing output field: smart_edit.execute() returns { changed, line, matches, method } — but the plugin ToolResult contract requires { title, output: string, metadata? }. The missing output causes h.split error when opencode's truncation layer tries to process undefined.

2. Normalization typo (line 96): normalizedSlice === normalizedSlice compares the same variable — always true. Should be normalizedSlice === normalizedOld. This made the bottom-up replacement loop run on every slice, not just matching ones.

3. No diff output: Tool returns only metadata — no human-readable/LLM-readable diff showing what changed.

Fix

• Return proper ToolResult with { title, output, metadata }
• Add formatDiff() helper that produces Claude-style diff blocks:

  ● Update(src/file.ts)
    ⎿  Added X lines, removed Y lines
        <lineNum>  <context>
        <lineNum> -<removed>
        <lineNum> +<added>
  

• Fix typo to correctly compare against normalizedOld
• Update tests to match new return format

[coderabbitai]

🔗 Related PRs

#15 - feat/14 append file tool [merged]
#19 - fix: include bodyless reviews in gh-pr-review output #18 [merged]
#20 - fix: correct after_line=-1 prepend position in append_file #16 [merged]
#24 - fix: align @typescript-eslint packages to 8.61.0 [merged]
#25 - feat: add gh_bot_review tool to parse AI bot findings #22 [merged]

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