refactor: prune code runtime surface

packages/code-runtime/code-runtime-worker/README.md

@@ -23,10 +23,12 @@ Every field is validated (positive numbers) and defaulted; there are no other tu
 - **Type-strip host-side, in execution context** — the program is wrapped in an async-function shell, stripped with `node:module`'s `stripTypeScriptTypes` (erasable syntax only — `enum`/namespaces are rejected as a program `exception` and no worker spawns), and sliced back out byte-positioned; it then executes as the body of an `AsyncFunction`, so top-level `await`/`return` work.
 - **The port assumes a hostile peer** — model code can reach `parentPort` and forge traffic, so every inbound message is shape-validated and REBUILT before anything reads it (`null`, primitives, junk types, and malformed payloads drop without a throw; forged extra fields never ride along), the host answers each call id at most once, resolves binding names as OWN properties only (a forged `constructor` cannot walk a prototype chain), drops post-settlement replies, and converts a non-cloneable binding resolution into an error reply. Forged `log`/`done` messages cannot bypass the caps: one host-side ledger bounds everything that lands in `logs`, and the completion value is re-capped host-side. Worker-side namespaces are null-prototype with `defineProperty`, so `__proto__`-shaped binding names are ordinary keys.
 - **Two independent budgets, because the peer is hostile** — `computeMs` meters the worker's MEASURED busy time (`worker.performance.eventLoopUtilization()` polling): a hot loop cannot hide behind a pending decoy dispatch, and a program awaiting a slow tool accrues nothing. `maxWallMs` backstops what busy time cannot see (awaiting a promise nobody resolves). Both funnel into `worker.terminate()`, which ends hot synchronous loops too; heap overflow surfaces as the worker's OOM exit (`kind: 'worker-exit'`).
-- **Logs stream eagerly** — console/stdout/stderr entries cross the port as they happen, so a timed-out or killed program still shows what it printed. ONE shared `maxLogBytes` ledger bounds everything: streamed entries, forged port traffic, and pipe bytes that bypass the patched streams (appended after), with the overflow marked in-band once.
+- **Logs stream eagerly** — console/stdout/stderr text crosses the port in emission order, so a timed-out or killed program still shows what it printed. ONE shared `maxLogBytes` ledger bounds everything: streamed text, forged port traffic, and pipe bytes that bypass the patched streams (appended after), with the overflow marked in-band once.
 - **Empty environment** — the worker gets `env: {}` and `execArgv: []`: no ambient credentials (stronger than the scrubbed-env rule for spawned commands) and no inherited loader flags.
 - **Dispose to quiescence** — teardown fails in-flight runs as `abort` and AWAITS each worker's exit before resolving.
 
 ## The worker entry, unbuilt and built
 
 `worker.ts` is deliberately erasable-only TypeScript with type-only cross-package imports: unbuilt (vitest/tsx), the host spawns `src/worker.ts` directly and Node's native type stripping loads it; built, the entry ships as the sibling CommonJS bundle `lib/worker.cjs` (its own tsdown entry). The CommonJS format is required because pkg's VFS Worker hook compiles filesystem-string entries as CommonJS. The host converts either entry URL to a filesystem string before constructing `Worker`, which works through both ordinary Node resolution and that pkg hook. The built path is pinned by `tests/built-lib.e2e.ts`, the real-load-path guard from [docs/testing.md](../../../docs/testing.md).
+
+The SDK surface is the default/named `WorkerCodeRuntime` class plus `Config`. The operational `./worker` subpath exists only as the packaged spawn entry; the wire protocol and bootstrap helpers are source-private implementation details.