fix(providers/pi): install PI_PACKAGE_DIR shim so Pi workflows run in a compiled binary

[Wirasm]

Summary

v0.3.9 made Pi boot-safe (lazy-load moved the crash out of archon startup) but not runtime-safe: the moment PiProvider.sendQuery() triggers the dynamic import, Pi's `config.js` fires its own module-init `readFileSync(getPackageJsonPath())` and we hit the exact same ENOENT the lazy-load was supposed to prevent. Discovered today by running an actual Pi workflow against a locally-compiled 0.3.9 binary; `/test-release` missed this because it only exercised `archon-assist` (Claude).

Boot-safe ≠ runtime-safe. The `provider-lazy-load.test.ts` regression test I added in #1355 covers only the former — this PR covers the latter.

Change

Before the dynamic `import('@mariozechner/pi-coding-agent')` in `sendQuery()`, install a `PI_PACKAGE_DIR` shim. Pi's `config.js` short-circuits the `dirname(process.execPath)` walk when that env var is set, so it reads from our stub instead. The stub is a minimal `{name, version, piConfig:{}}` JSON written once to `tmpdir()/archon-pi-shim/package.json` (idempotent existsSync check). Pi only reads `piConfig.name`, `piConfig.configDir`, and `version` from that file — all optional — so the surface is genuinely minimal.

Localized to `PiProvider`. No global state, no upstream fork, no mutation of shared config. Claude and Codex providers are unaffected (their SDKs don't have this class of init-time side effect).

E2E verification

Before patch, on a compiled 0.3.9 binary:
```
[main] Failed: ENOENT: no such file or directory,
open '/private/tmp/package.json'
at readFileSync (unknown)
at init_config
```

After patch, same compiled binary running `archon workflow run test-pi --no-worktree` against a workflow with `provider: pi` + `model: anthropic/claude-haiku-4-5`:
```
{"module":"provider.pi","piProvider":"anthropic","modelId":"claude-haiku-4-5","msg":"pi.session_started"}
hi
Workflow completed successfully.
```

Regression test

Added a unit test that deletes `process.env.PI_PACKAGE_DIR`, calls `sendQuery()` via the fast-fail "no model" path (returns before any Pi SDK work), and asserts the shim still ran and set the env var. Paired with the existing boot-safety test, both halves of the bug are now covered.

Test plan

• `bun run validate` green
• Manual: `bun build --compile --minify --target=bun-darwin-arm64` + `archon workflow run ` returns a response
• Before cutting next release: `/test-release` should run a Pi workflow end-to-end, not just Claude (separate follow-up)

Summary by CodeRabbit

• Bug Fixes

  • Fixed Pi provider initialization by ensuring proper package directory configuration before dynamic imports in compiled environments.

• Tests

  • Added regression test to verify Pi provider's package directory setup occurs before SDK initialization.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 51ecb0e9-2644-4abc-9f8d-a1e8eb1e3d39

📥 Commits

Reviewing files that changed from the base of the PR and between 6f86402 and 00f416f.

📒 Files selected for processing (2)

• packages/providers/src/community/pi/provider.test.ts
• packages/providers/src/community/pi/provider.ts

---

📝 Walkthrough

Walkthrough

The changes introduce a shim directory mechanism that initializes process.env.PI_PACKAGE_DIR before Pi SDK dynamic imports occur, enabling proper package.json resolution in compiled environments. A regression test validates this initialization ordering.

Changes

Cohort / File(s)	Summary
Pi Provider Implementation packages/providers/src/community/pi/provider.ts	Added Node.js filesystem/os/path imports and ensurePiPackageDirShim() helper function that creates a temporary archon-pi-shim directory with a minimal package.json stub and sets PI_PACKAGE_DIR environment variable. Updated sendQuery() to invoke this helper before dynamic Pi SDK imports.
Pi Provider Tests packages/providers/src/community/pi/provider.test.ts	Added regression test that verifies PI_PACKAGE_DIR environment variable is initialized and includes archon-pi-shim when sendQuery() is invoked, ensuring the shim setup occurs before Pi SDK dynamic imports.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• feat(providers/pi): best-effort structured output via prompt engineering #1297: Modifies PiProvider.sendQuery() with additional logic changes including prompt augmentation and schema handling.
• fix(providers/pi): lazy-load Pi SDK to unbreak compiled archon binary #1355: Refactors Pi provider startup behavior through lazy-loading of the Pi SDK to avoid top-level imports.
• feat(providers): add Pi community provider (@mariozechner/pi-coding-agent) #1270: Modifies packages/providers/src/community/pi/provider.ts implementation and import/resolution behavior.

Poem

🐰 A shim appears, cozy and small,
In temp directories standing tall,
Package paths now have a home,
No more imports left to roam,
Pi SDK hops with glee! 🥕

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/pi-runtime-shim

---

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