code-reviewer

Adds a code_reviewer subagent tool that adapts The Last Harness code-reviewer prompt into a standalone pi extension.

Use it when you want an isolated second-pass review of a proposed change against the local checkout. The subagent uses read-only built-in tools plus any configured MCP tools, checks ticket fit and scope first, then looks for diff mismatches, correctness bugs, security/safety issues, unnecessary complexity, and missing validation.

Install

Standalone npm package

pi install npm:@diegopetrucci/pi-code-reviewer

Collection package

pi install npm:@diegopetrucci/pi-extensions

GitHub package

pi install git:github.com/diegopetrucci/pi-extensions

Then reload pi:

/reload

code_reviewer tool behavior

The tool accepts:

• task — required review target and success criteria
• diff — optional diff, patch, or change summary
• context — optional extra constraints or known risks

When called, it launches an isolated in-memory child agent with:

• no inherited extensions, skills, prompt templates, themes, context files, or agents files;
• an auto-selected review model that prefers contrarian-style opposite-provider and opposite-family candidates before same-provider fallbacks;
• automatic model candidates constrained to the current Pi session's model scope when that scope is non-empty;
• requested thinking taken from the active session when available, otherwise defaulting to high for reasoning models and off for non-reasoning models, then clamped to the selected model's supported level;
• read-only built-in tools: read, grep, find, ls, and guarded bash;
• configured MCP tools (run without confirmation in the subagent; may have side effects; use for evidence gathering only; requires host Pi >=1.0.4; older hosts degrade to no MCP, no error); the global mcp.json always applies; a project .pi/mcp.json is loaded only when the host session has already trusted the project;
• a local-checkout path guard for file inspection;
• a bash guard that allows only direct read-only git, gh, or pwd invocations.

The review prompt prioritizes:

1. ticket fit and scope
2. diff accuracy
3. correctness and regressions
4. security and safety
5. simplicity and maintainability
6. tests and validation gaps

The model report is concise and includes a verdict, findings, validation notes, and a scope check. The tool appends a run-details suffix with the final selected model, effective thinking level, turn count, tool calls, duration, working directory, and tools used.

Read-only guarantees

• The subagent is explicitly instructed not to implement changes.
• Runtime guards block write/edit tools, shell control operators, pipelines, redirection, path traversal outside the checkout, mutating git/gh commands, npm/publish commands, and other filesystem mutation.
• Runtime guards apply to built-in tools only; configured MCP tools pass the guard, run without confirmation, and are limited only by prompt guidance.
• Built-in file-inspection tools are preferred over shell commands for local files.

Example

Use code_reviewer on this task before merging:

{
  "task": "Review ticket pe-7lpt implementation for scope fit and correctness.",
  "context": "Focus on whether the new extension stays runtime-only and keeps tools read-only."
}

Limitations

• The subagent has an 8-turn and 8-minute budget.
• The review quality depends on the local checkout matching the change being reviewed.
• gh-based inspection is available only when GitHub CLI is installed and authenticated, but the tool can still review local changes without it.