# 01. Extension scaffolding and project structure

meta:
  id: pygienium-01
  feature: pygienium
  priority: P1
  depends_on: []
  tags: [infrastructure, setup]

objective:

- Establish the pygienium extension directory, package.json, tsconfig, and a minimal index.ts that loads without error and surfaces a startup notification.

deliverables:

- `pygienium/package.json` with pi package manifest (`pi.extensions`, keywords, peer deps echoing piolium)
- `pygienium/tsconfig.json` (extends the repo tsconfig)
- `pygienium/src/index.ts` default-export factory registering a `session_start` notify + a stub `/pygienium-help`
- `pygienium/` subdirectories: `src/`, `src/modes/`, `src/checks/`, `agents/`, `skills/` (empty, with `.gitkeep`)
- Verified load: `pi -e ./pygienium/src/index.ts -p "/pygienium-help"` runs without throwing

steps:

- Create the `pygienium/` tree and empty subdirectories
- Author `package.json`: name `pygienium`, type module, `pi.extensions: ["./src/index.ts"]`, peerDeps mirroring piolium (`@earendil-works/pi-coding-agent`, `typebox`, etc.), engines bun >=1.1.0
- Author `tsconfig.json` referencing the parent `tsconfig.json`
- Author `src/index.ts`: import `ExtensionAPI`, default-export factory that registers a `session_start` notify ("Pygienium loaded. Run /pygienium-help.") and a `/pygienium-help` command printing a placeholder line
- Confirm the extension auto-discovers from `~/.pi/agent/extensions/pygienium/src/index.ts` (per docs, subdir `index.ts`); if discovery prefers `pygienium/index.ts`, adjust entry path in package.json

tests:

- Manual: run `pi -e ./pygienium/src/index.ts -p "/pygienium-help"`; confirm the placeholder help renders
- Manual: start pi in `~/.pi/agent/extensions` and confirm the startup notify appears without `session_start` errors

acceptance_criteria:

- The directory tree and package.json exist with valid JSON
- `pi` loads the extension via auto-discovery with no load errors
- `/pygienium-help` responds with a non-empty line

validation:

- `node -e "JSON.parse(require('fs').readFileSync('pygienium/package.json','utf8'))"` exits 0
- `pi -e ./pygienium/src/index.ts -p "/pygienium-help"` prints the placeholder

notes:

- Place the extension in `~/.pi/agent/extensions/pygienium/` so it auto-discovers and hot-reloads with `/reload`
- Do NOT add backward-compat shims or migration paths (engineering rule)
- Keep index.ts minimal here; full command wiring lands in task 06