/add-tool — add a new Forge tool

Adding a tool touches four places. Do all four in one change, or the tool is half-registered.

Tool name: $ARGUMENTS (kebab-case, e.g. read-manifest).

1. Implementation — src/tools/$ARGUMENTS.ts

• Import Tool from ../types and ForgeRuntimeError from ../types/errors.
• Define a zod schema for input and output.
• Declare both metadata fields on the tool schema:
  • sideEffect: none | read | write | network | exec
  • risk: low | medium | high | critical
• Route every filesystem access through src/sandbox/fs.ts helpers.
• Route every shell command through src/sandbox/shell.ts + classifyCommandRisk.
• Request permission via requestPermission from src/permissions/manager.ts before the side-effecting call, not after.
• Return { ok: true, data } / { ok: false, error }. Throw only for programmer errors.

2. Registration — src/tools/registry.ts (indirectly)

Follow the existing pattern used by sibling tools: export a register helper or a tool constant and wire it up wherever registerTool is called at startup. Read one existing tool (e.g. src/tools/read-file.ts) before writing yours.

3. Unit test — test/unit/$ARGUMENTS.test.ts

At minimum, cover:

• happy path with valid input
• invalid input (zod rejection)
• permission denied → structured error, not throw
• path-escape attempt is refused by the sandbox
• (if shell) critical command is hard-blocked

Use vi.mock for the permission manager and sandbox boundaries. No real filesystem writes outside os.tmpdir().

4. Documentation

If the tool is user-visible, add a row to the tools table in docs/ARCHITECTURE.md (it lists all 18 tools today). Update the count in README.md "At a glance" if it changed.

Verification

Run /verify when you're done. The test count should increase by the number of tests you added.