FE-843: Toolchain profile expansion — TS runtimes + live profile selection

[kostandinang]

Stack Context

Expands the FE-829 toolchain contract so brunch cook can build on more technologies than bun, and so the profile selection path actually works.

What?

• Data-driven profile registry (project-profile.ts) -- profiles are data literals (path templates + argv template + conventions prose) compiled into the unchanged Toolchain interface. Adds node-vitest, node-test, node-jest, deno alongside bun/brunch; registry invariants pinned enumerably over every entry. Adding a runtime = one data entry.
• Live + strict selection -- brunch plan --profile=<id> (validated); the emitter resolves the chain once (--profile flag >> spec profile >> architect-classified >> bun) and stamps the resolved id into plan.yaml on both the authored and fallback paths, so cook always reads the profile the emitter used (I130-K). resolveToolchain now throws UnknownProfileError on a typo'd id instead of silently running bun; absent stays lenient for hand-authored fixtures.
• Architect classifies the stack from spec prose -- optional profile enum on the architectPlan schema (null when the spec is silent); a hallucinated id fails schema parse and rides the existing deterministic fallback. No host introspection (D160-K intact).

Why?

Before this branch both implemented profiles were TypeScript and the selection path was dead -- nothing populated snapshot.profile, so every cook run silently resolved to bun, and a typo'd profile id silently defaulted rather than erroring. Adding profiles without live selection changes nothing at runtime; live selection without strictness hides real misconfiguration.

Deliberately not included (recorded in PLAN as follow-ons): a harness install verb (the cook agent scaffolds + installs per A98), fail/infra test-outcome split, brownfield drift-check at cook open, brunch detect. Outer-loop validation outstanding: a greenfield cook smoke with --profile=node-vitest as the conventions-prose oracle.

[kostandinang]

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• FE-864: Plan orchestrator brownfield enhancements #212 : 2 dependent PRs (#213 , #223 )
• FE-843: Toolchain profile expansion — TS runtimes + live profile selection #198 👈 (View in Graphite)
• FE-841: Embed pi as an in-process SDK to drop the external pi CLI dependency #194 : 1 other dependent PR (#211 )
• main

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PR Summary

Low Risk
Plan/cook CLI and profile registry changes with broad unit test coverage; behavior change is mainly failing fast on bad profile ids instead of silently using bun.

Overview
FE-843 expands cook/plan toolchain support beyond implicit bun defaults: profiles become data literals compiled into the existing Toolchain interface, with new ids node-vitest, node-test, node-jest, and deno (plus existing bun / brunch).

Live selection wires brunch plan --profile=<id> through parseProfileId → plan-runner → emitPlanFromSnapshot. The emitter resolves the profile once with precedence --profile ≫ snapshot.profile ≫ architect-classified ≫ bun, stamps it on plan.yaml on both success and architect-fallback paths, and derives verification targets from that toolchain.

Strict vs lenient: resolveToolchain(undefined) still defaults to bun for hand-authored fixtures; any present but unknown id throws UnknownProfileError (replacing silent bun fallback)—so typos in emitted plans fail loudly when brunch cook loads them.

The build architect gains an optional profile field in its Zod schema and prompt (classify from spec prose only; invalid/hallucinated ids fail parse and trigger deterministic projection fallback). memory/PLAN.md documents the completed toolchain-profile-expansion frontier.

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[kostandinang]

Follow-on work tracked in FE-864 — Orchestrator enhancements: brownfield feature delivery from spec. This branch's deferred items (structured spec-profile field, outstanding --profile=node-vitest greenfield cook smoke, install-verb / fail-infra split / brownfield drift-check / brunch detect) will be evolved there.

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