fix(agent): unbreak the codex local-tools MCP server ESM bundle

[tatoalo]

Problem

Cloud tasks running on a Codex model cannot commit or open PRs: the model reports that git_signed_commit is not available, even though the session config injects the posthog-code-tools MCP server and the agent-server logs hasLocalTools: true.

Root cause: the bundled dist/adapters/codex-app-server/local-tools-mcp-server.js crashes at import time with Dynamic require of "fs" is not supported. noExternal inlines @posthog/git's CJS dependencies (simple-git → @kwsites/file-exists) into the ESM bundle, where esbuild's require shim throws. Codex spawns the server, the process dies before answering initialize, codex emits mcpServer/startupStatus/updated {status: "failed"} (which the adapter ignored), and the signed-git tools silently never reach the model. The Claude adapter is unaffected because it registers these tools in-process; only the Codex path uses this standalone bundle.

Changes

• Add a createRequire banner to the ESM tsup config so inlined CJS require(...) calls resolve when an entry runs directly under node.
• Add a post-build smoke check (build/verify-local-tools-mcp-server.mjs, wired into pnpm build) that boots the dist server exactly like codex does and asserts tools/list includes the signed-git tools — this fails the build on any future bundling regression.
• Log a warning when codex reports an MCP server startup failure instead of dropping the notification, so this class of failure is diagnosable from agent logs.

[trunk-io]

Merging to main in this repository is managed by Trunk.

• To merge this pull request, check the box to the left or comment /trunk merge below.

After your PR is submitted to the merge queue, this comment will be automatically updated with its status. If the PR fails, failure details will also be posted here

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 9860a3d.}

[stamphog]

Gates denied this PR because it modifies build toolchain files (tsup.config.ts and the package.json build script), which require human review. These are non-trivial bundler changes — adding a banner shim to inject require into ESM output affects how all entries in that tsup config are bundled, not just the MCP server.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "fix(agent): unbreak the codex local-tool..." | Re-trigger Greptile}

[stamphog]

Gates denied this PR because it modifies build toolchain files (tsup.config.ts and package.json build script), which are on the deny-list and require human review. The bundler banner shim injected into ESM output affects all entries in that tsup config, not just the MCP server fix.