fix(hooks): throw agent-friendly errors when todowrite receives invalid input

[kdcokenny]

Summary

Throw descriptive, agent-friendly errors when todowrite receives malformed input instead of silently continuing.

Problem

When LLMs pass todos as a JSON string instead of an array, the original fix silently parsed and continued. This doesn't help the agent correct its behavior.

Solution

Throw errors with the [todowrite ERROR] prefix that include:

• What was received
• What was expected
• How to fix it

Follows fail fast, fail loud and the OpenCode agent-friendly error pattern.

Changes

• src/hooks/claude-code-hooks/index.ts: Refactored todowrite string parsing to throw agent-friendly errors

Testing

Manual verification with ocx ghost:

# Valid input - creates todo
ocx ghost opencode run "Create a todo list with one item" --profile omo-dev
# ✅ Todo created successfully

# Invalid input - agent-friendly error
ocx ghost opencode run "Call todowrite with todos as '{\"id\": \"1\"}'" --profile omo-dev  
# ✅ [todowrite ERROR] Parsed JSON is not an array. Received type: object...

Closes #625

[greptile-apps]

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[cubic-dev-ai]

1 issue found across 1 file

Confidence score: 4/5

• Appending ... unconditionally in src/hooks/claude-code-hooks/index.ts can mislead the agent about true input length, so trimming logic should only add the ellipsis when the string actually exceeds 100 characters.
• Overall change is still low risk and easy to adjust, so this PR looks safe to merge once that display detail is corrected.
• Pay close attention to src/hooks/claude-code-hooks/index.ts - ensure ... only appears when truncation occurs.

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:195">
P2: Ellipsis is always appended even when string isn't truncated, which misleads the agent about the actual input. Only show `...` when the string exceeds 100 characters.</violation>
</file>

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