fix: let subagents see asynchronously-registered extension tools (MCP)#141
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fix: let subagents see asynchronously-registered extension tools (MCP)#141philipmw wants to merge 1 commit into
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Subagents could not use tools provided by MCP extensions (e.g. pi-mcp-extension), even though those tools work in the main agent. pi-mcp registers its tools asynchronously from its session_start handler, after connecting to MCP servers — never during synchronous extension load. runAgent, however, snapshotted extension.tools.keys() into a static `tools:` allowlist right after loader.reload() and before bindExtensions() fires session_start. In pi-mono that allowlist (allowedToolNames) is frozen at construction and gates the tool *registry* itself, so MCP tools — registered later — were dropped permanently, not just deactivated. Scope extension tools via the session's live denylist instead of a frozen allowlist, matching how the main agent stays in sync. When extensions load and there is no `ext:` narrowing, pass `tools: undefined` (allowlist unset, so the live isAllowedTool gate admits tools whenever they register) and express scope as `excludeTools` = this extension's own orchestration tools + built-ins the agent didn't ask for + disallowedTools. Because an unset allowlist only activates pi's four default built-ins at turn 1, repair the active set post-bind via setActiveToolsByName(getAllTools()); tools registered later (lazy MCP servers) auto-activate through pi's refresh path. The static-allowlist path is retained unchanged for noExtensions/isolated and for `ext:` narrowing, where the exact set is known up front. May solve issue tintinweb#125. I (the human) tested this manually by setting my local checkout of pi-subagents as the extension, then asking the LLM to spawn a subagent and use a search tool. Previously, it couldn't -- and now it can. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Subagents could not use tools provided by MCP extensions (e.g. pi-mcp-extension), even though those tools work in the main agent. pi-mcp registers its tools asynchronously from its session_start handler, after connecting to MCP servers — never during synchronous extension load. runAgent, however, snapshotted extension.tools.keys() into a static
tools:allowlist right after loader.reload() and before bindExtensions() fires session_start. In pi-mono that allowlist (allowedToolNames) is frozen at construction and gates the tool registry itself, so MCP tools — registered later — were dropped permanently, not just deactivated.Scope extension tools via the session's live denylist instead of a frozen allowlist, matching how the main agent stays in sync. When extensions load and there is no
ext:narrowing, passtools: undefined(allowlist unset, so the live isAllowedTool gate admits tools whenever they register) and express scope asexcludeTools= this extension's own orchestration tools + built-ins the agent didn't ask for + disallowedTools. Because an unset allowlist only activates pi's four default built-ins at turn 1, repair the active set post-bind via setActiveToolsByName(getAllTools()); tools registered later (lazy MCP servers) auto-activate through pi's refresh path. The static-allowlist path is retained unchanged for noExtensions/isolated and forext:narrowing, where the exact set is known up front.May solve issue #125.
I (the human) tested this manually by setting my local checkout of pi-subagents as the extension, then asking the LLM to spawn a subagent and use a search tool. Previously, it couldn't -- and now it can.