feat(hooks): wire mcp_tool + agent hook dispatchers in the agent loop#114
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The HookDispatcher already had mcp_tool + agent handler cases, but nothing
supplied their dispatchers, so those hook types no-op'd with "no dispatcher
wired". The host CLI can't supply them at HookDispatcher construction time:
mcp_tool needs the live tool registry (MCP tools are registered as
`mcp__<server>__<tool>`) and `agent` needs the sub-agent runner — both only
exist once the agent loop starts. So the loop wires them itself.
- HookDispatcher: mcpToolDispatcher/agentDispatcher are now settable via
setMcpToolDispatcher()/setAgentDispatcher() (+ hasX() probes). Setters
no-op if a dispatcher was already supplied, so explicit/plugin wiring wins.
- agent.ts: after building runSubAgent, wires:
· mcp_tool → resolves `mcp__<server>__<tool>` from the registry and runs it
in the live ToolContext (maps isError → exitCode).
· agent → runs the named sub-agent via runSubAgent, with a re-entrancy guard
(the dispatcher is shared with the sub-agent loop, so a hook firing during
the sub-agent run is skipped rather than cascading). Only wired below the
sub-agent recursion cap.
Tests: +4 dispatcher (set/has, late-wired invocation for both types,
constructor-wins) +2 agent (mcp_tool hook runs a registered MCP tool
end-to-end through the loop; unregistered tool reported without throwing).
Core suite 564 green.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
Activates two hook handler types that were implemented but inert. The
HookDispatcheralready hadmcp_toolandagentcases, but nothing supplied their dispatchers — so configuring those hooks just produced"no mcpToolDispatcher wired"/"no agentDispatcher wired"on stderr.They can't be wired at the host's
HookDispatcherconstruction site (the "ordering" problem):mcp_toolneeds the live tool registry (MCP tools are registered asmcp__<server>__<tool>) andagentneeds the sub-agent runner — both only exist once the agent loop has started. So the agent loop wires them itself, which is the correct layer and needs no changes torepl.ts/headless.ts.Changes
hooks/dispatcher.ts—mcpToolDispatcher/agentDispatcherbecome settable:setMcpToolDispatcher(fn)/setAgentDispatcher(fn)+hasMcpToolDispatcher()/hasAgentDispatcher()probes.agent.ts— after buildingrunSubAgent, the loop wires:mcp__<server>__<tool>fromopts.toolsand executes it in the liveToolContext(isError→ non-zero exit code; missing tool → descriptive stderr, no throw).runSubAgent, guarded by:Tests
dispatcher.test.ts):set/hasround-trip, late-wired invocation for bothmcp_toolandagent, and constructor-wins-over-setter.agent.test.ts): aPostToolUsemcp_toolhook resolves + runs a registeredmcp__test__echotool end-to-end through the real agent loop (asserts both dispatchers got wired and the tool ran exactly once); an unregistered MCP tool is reported without throwing.Core suite 564 green (+6); full repo suite green via pre-commit.
Notes
🤖 Generated with Claude Code