Steward Nix packaging

The flake exposes packages.steward-pi-runtime and includes it in packages.default (steward). The runtime owns bin/pi, bin/steward-pi-helper, and lib/steward/{runtime,node_modules,package.json}. pi starts the official unbundled @earendil-works/pi-coding-agent/dist/cli.js with Node 24; it is not the npm bundled CLI.

The runtime prepares the locked package graph before copying it: the Pi SDK, AI, TUI, and pi-subagents 0.19.0 resolve from one physical graph. Its evaluated extensionRoot and nodeModules passthru paths identify that graph. The Pi wrapper PATH contains its helper plus steward, rg, and fd; the helper is an absolute Node 24 wrapper.

Build and run the isolated packaged smoke probe from a checkout:

runtime=$(nix build .#steward-pi-runtime --no-link --print-out-paths)
package=$(nix build .#default --no-link --print-out-paths)
node runtime/package-smoke.mjs --package-root "$package" --runtime-root "$runtime"

The smoke probe requires the default package itself to provide the helper, Pi wrapper, runtime assets, and SDK/AI/TUI/subagents manifests. It compares their resolved file paths with the explicit paired runtime, then runs the default package's bin/pi --version. A test-only NODE_OPTIONS --import observer records the actual CLI entry and Node executable: the entry must be the runtime's unbundled dist/cli.js, never dist/bundle/cli.js, and the recorded Node must be version 24. That recorded packaged Node runs the physical graph identity check and the real generic-child construction probe with an isolated offline home and blocked network APIs.

The real default packaged helper wrapper is exercised for both composition and quota with test-only Node registerHooks model fixtures. The composition fixture records one controlled model call and validates its exact result. The quota fixture drives one public getAuth resolution and one fixed usage fetch, then validates the strict result and that its synthetic credential sentinel is absent from helper argv and output. The package smoke does not create or inspect the quota cache; the source integration test separately proves the cache omits the credential sentinel. No live model, authentication, provider, ntfy, external network, or deployment service is contacted. Existing negative controls still prove copied/bypassed extensions and an independent SDK accessor fail physical-graph classification.

Consumer configuration does not yet replace its existing Pi package. That coordinated cutover remains responsible for pointing Pi at the runtime's evaluated extension root and for user-level wiring.