feat(pi): inject first-party local MCP tools

[jonathanlab]

Summary

• expose the shared posthog-code-tools MCP server to Pi cloud runs through Pi runtime capabilities
• move the local-tools MCP server out of the Codex adapter and reuse it from Pi
• remove the redundant Pi runtime factory and centralize capability-to-MCP resolution in createPiRpcClient
• package the MCP child with the Electron main build and resolve it from the Vite runtime

Testing

• pnpm --filter agent build
• pnpm --filter code typecheck
• targeted agent, harness, workspace-server, and desktop Pi tests

upload_artifact remains cloud-only; normal desktop Pi sessions retain local capabilities.

[trunk-io]

🚫 This pull request was removed from the merge queue because it was canceled by Jonathan Mieloo (a GitHub user). See more details here.

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[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 0573a01.}

[greptile-apps]

MCP child remains inside ASAR

When a packaged desktop Pi session enables a first-party local tool, the app launches .vite/build/mcp-server.js as a standalone Node script, but this new asset is not included in asarUnpack alongside rpc-host.js, causing the MCP child and its tools to fail at startup.

Knowledge Base Used: PostHog Code Desktop App (apps/code)

Prompt To Fix With AI

This is a comment left during a code review.
Path: apps/code/vite-main-plugins.mts
Line: 175-179

Comment:
**MCP child remains inside ASAR**

When a packaged desktop Pi session enables a first-party local tool, the app launches `.vite/build/mcp-server.js` as a standalone Node script, but this new asset is not included in `asarUnpack` alongside `rpc-host.js`, causing the MCP child and its tools to fail at startup.

**Knowledge Base Used:** [PostHog Code Desktop App (`apps/code`)](https://app.greptile.com/posthog-org-19734/-/custom-context/knowledge-base/posthog/code/-/docs/apps-code-desktop.md)

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

[greptile-apps]

Comments Outside Diff (1)

1. packages/harness/src/extensions/mcp/extension.ts, line 3497-3513 (link)

   Config errors drop runtime tools

   When the global or project mcp.json is malformed or unreadable, this handler returns before mergeRuntimeServers runs, causing the trusted posthog-code-tools server and its cloud Pi tools to be absent for the session.

   Knowledge Base Used:

   • Harness (hog/harness CLI)
   • Agent SDK (packages/agent)
   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: packages/harness/src/extensions/mcp/extension.ts
   Line: 3497-3513
   
   Comment:
   **Config errors drop runtime tools**
   
   When the global or project `mcp.json` is malformed or unreadable, this handler returns before `mergeRuntimeServers` runs, causing the trusted `posthog-code-tools` server and its cloud Pi tools to be absent for the session.
   
   **Knowledge Base Used:**
   - [Harness (`hog`/`harness` CLI)](https://app.greptile.com/posthog-org-19734/-/custom-context/knowledge-base/posthog/code/-/docs/harness-cli.md)
   - [Agent SDK (`packages/agent`)](https://app.greptile.com/posthog-org-19734/-/custom-context/knowledge-base/posthog/code/-/docs/agent-sdk.md)
   
   ---
   
   For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Prompt To Fix All With AI

### Issue 1
apps/code/vite-main-plugins.mts:175-179
**MCP child remains inside ASAR**

When a packaged desktop Pi session enables a first-party local tool, the app launches `.vite/build/mcp-server.js` as a standalone Node script, but this new asset is not included in `asarUnpack` alongside `rpc-host.js`, causing the MCP child and its tools to fail at startup.

### Issue 2
packages/harness/src/extensions/mcp/extension.ts:3497-3513
**Config errors drop runtime tools**

When the global or project `mcp.json` is malformed or unreadable, this handler returns before `mergeRuntimeServers` runs, causing the trusted `posthog-code-tools` server and its cloud Pi tools to be absent for the session.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "feat(pi): inject local MCP tools" | Re-trigger Greptile}

[jonathanlab]

/merge stop

[jonathanlab]

/trunk stop

[veria-ai]

PR overview

All previously flagged issues have been addressed. No open security concerns remain on this pull request.

Security review

No open security issues remain on this pull request.

Fixed/addressed: 1 · PR risk: 0/10