fix(hooks): handle todowrite todos passed as string instead of array

[SJY0917032]

Summary

• Fix todowrite tool failing with "expected array, received string" error when LLMs pass todos as a JSON string instead of an array
• Update tool.execute.before hook to parse string input before Zod validation

Problem

When invoking the todowrite tool, some LLM tool-calling interfaces pass the todos parameter as a JSON string instead of an array. This caused failures like:

Error: The todowrite tool was called with invalid arguments: [
  {
    "expected": "array",
    "code": "invalid_type",
    "path": ["todos"],
    "message": "Invalid input: expected array, received string"
  }
]

The root cause: OpenCode's TodoWriteTool uses Zod schema z.array(...) for validation, but the LLM sometimes sends the array as a stringified JSON.

Solution

Add a pre-validation check in tool.execute.before hook that detects when todos is a string and parses it to an array before the tool execution.

This is similar to the fix in #532 which handled skill_mcp arguments passed as object instead of string (opposite direction).

Test Plan

• bun run typecheck passes
• bun run build succeeds
• Manually verified todowrite works after the fix (tested in local OpenCode session)

---

Summary by cubic

Fixes todowrite failures when LLMs send todos as a JSON string. The before-execute hook now parses string todos to an array (with success/error logs) before Zod validation so the tool runs correctly.

^{Written for commit f105ceb. Summary will update on new commits.}

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[SJY0917032]

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[cubic-dev-ai]

1 issue found across 1 file

Confidence score: 3/5

• src/hooks/claude-code-hooks/index.ts assumes the parsed LLM response is always an array, so a valid JSON scalar like 'null' or '{}' would slip through and likely break downstream logic.
• Because this is a concrete parsing/validation gap, there’s a moderate chance of user-facing errors if an LLM returns unexpected JSON.
• Pay close attention to src/hooks/claude-code-hooks/index.ts - add post-parse validation to ensure the value is actually an array.

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="src/hooks/claude-code-hooks/index.ts">

<violation number="1" location="src/hooks/claude-code-hooks/index.ts:207">
P2: After `JSON.parse`, the result should be validated as an array. If an LLM sends a non-array JSON string (e.g., `'null'`, `'{}'`), parsing succeeds but produces a non-array value. The log message "parsed todos string to array" would be misleading, and it's inconsistent with the pattern in `todo.ts` which uses `Array.isArray()` after parsing.</violation>
</file>

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[kdcokenny]

Closing in favor of #726. The original approach used silent logging which doesn't follow our fail-fast philosophy. #726 throws agent-friendly errors instead. Thanks for the initial contribution!