Pi generated extension should default-export its factory function

[musichen]

Summary

The generated Pi extension currently exports a named register(pi) function, but Pi expects an extension file to default-export a factory function.

This makes Pi fail on startup whenever the generated extension is present.

Environment

• codebase-memory-mcp: 0.10.1
• Pi coding agent: 0.84.1
• macOS arm64

Repro

After installing codebase-memory-mcp with Pi integration, the generated file at:

~/.pi/agent/extensions/cbmem.ts

contained:

export function register(pi) {
  pi.registerTool({ name: 'index_repository', run: (args, ctx) => call('index_repository', args, ctx?.signal) });
  // ...
}

Running any Pi command with extensions enabled then failed:

pi doctor

with:

Error: Failed to load extension "/Users/musichen/.pi/agent/extensions/cbmem.ts": Extension does not export a valid factory function: /Users/musichen/.pi/agent/extensions/cbmem.ts
Hint: Start without extensions using "pi -ne".

Local fix verified

Changing the generated export to a default factory fixed Pi startup:

-export function register(pi) {
+export default function (pi) {

After this change, both commands worked with extensions enabled:

pi doctor
pi -p 'reply exactly: pi-ok'

Expected generator output

The Pi extension generator should emit:

export default function (pi) {
  pi.registerTool({ name: 'index_repository', run: (args, ctx) => call('index_repository', args, ctx?.signal) });
}

Related

I also opened a Pi issue asking for a clearer loader diagnostic when the default export is missing:

earendil-works/pi#7985

[DeusData]

Confirmed, and thank you @musichen — this is our bug, introduced when the Pi extension started being generated from the tool registry (#1392, shipped in v0.10.0). src/cli/client_adapter.c emits export function register(pi), and Pi wants a default-exported factory.

What makes it worse than a cbm-only failure: a broken extension file makes every Pi command fail to load, not just ours — pi doctor included, exactly as you saw. So this is queued for the next patch release.

Immediate unblock if you need Pi working right now: delete ~/.pi/agent/extensions/cbmem.ts (cbm keeps working through its MCP server registration; only the extension surface goes away), or edit it to export default function (pi) { ... } with the same body.

[musichen]

A test-backed fix is available in #1553.