52 lines
7.3 KiB
Markdown
52 lines
7.3 KiB
Markdown
# @deepseek-ai/dsh-code-runtime-worker
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Worker-thread implementation of the [`@deepseek-ai/dsh-code-runtime`](../code-runtime/README.md) seam: `WorkerCodeRuntime` runs each program in ONE fresh Node `worker_threads.Worker` — TypeScript in, type-stripped host-side, bindings bridged over the message port, `{ value, logs, error? }` out. **Containment, not a security boundary**: trust posture is bash-equivalent by design (the [Code Mode Agent Note](../../../.agents/notes/implemented/feature/2026-06-15-code-mode.md) § Trust posture), with containment bash does not have — separate isolate, empty environment, heap cap, hard termination.
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## Config
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```yaml
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- id: code-runtime
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name: '@deepseek-ai/dsh-code-runtime-worker'
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config:
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computeMs: 60000 # busy-time budget (measured event-loop active time)
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maxWallMs: 600000 # wall-clock ceiling; never pauses for anything
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maxOutputBytes: 67108864 # combined serialized outer-output cap (64 MiB)
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maxOldGenerationSizeMb: 512 # worker heap cap (resourceLimits)
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```
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Every field is validated and defaulted; `maxOutputBytes` is a safe integer of at least four bytes, the remaining fields are positive finite numbers, and there are no other tunables.
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## Design
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- **One fresh worker per run, no pooling** — a program's world dies with its worker: no cross-run state to log, state bleed unrepresentable, runs reconstructable from the session log alone.
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- **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.
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- **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 validates every binding resolution and completion as lossless JSON. Forged `log`/`done` messages cannot bypass the outer cap: the host repeats validation and accounts every admitted log plus the completion or diagnostic. Worker-side namespaces are null-prototype with `defineProperty`, so `__proto__`-shaped binding names are ordinary keys.
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- **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'`).
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- **Intermediate binding values are complete JSON** — binding arguments and resolutions undergo iterative lossless-JSON validation, flatten into a bounded-depth pre-order wire value for structured clone, and rebuild iteratively on the other side. They have no byte, JavaScript call-stack, or nested structured-clone depth cap. They never enter the outer-output ledger or model context; provider/executor acquisition bounds and process/worker memory remain the limits.
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- **Logs stream eagerly into one outer ledger** — console/stdout/stderr text crosses the port in emission order, so a timed-out or killed program still shows what it printed. Native writes that bypass the patched stream slots arrive on pipes independent of the completion port; settlement therefore continues bounded pipe capture until worker termination completes before materializing the result. `maxOutputBytes` accounts the JSON serialization of the outer `logs` array plus the completion value or failure-message payload; fixed `CodeRunResult` field names, braces, the bounded error-kind tag, and later presentation whitespace are outside that variable-payload ledger. At or below the cap the exact value returns; a lossy completion is `invalid-output`, and a combined overflow is `output-limit` rather than a substituted inspected string. The failure retains the fitting captured prefix and later follows the normal outer `run_code` spill policy.
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- **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.
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- **Dispose to quiescence** — teardown fails in-flight runs as `abort` and AWAITS each worker's exit before resolving.
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## The worker entry, unbuilt and built
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Source mode loads erasable-only `src/worker.ts` through Node's native type stripping. Its transitive runtime closure contains only Node built-ins and relative source modules, so a fresh checkout never requires a sibling workspace package's unbuilt `lib/` export. The worker-local JSON snapshotter is parity-tested against the session-owned canonical boundary; both sides flatten and rebuild validated values around the message port so application nesting never reaches structured clone. Built mode passes the sibling `lib/worker.cjs` as a filesystem path because pkg's VFS Worker hook expects CommonJS; the same path works under ordinary Node. `tests/built-lib.e2e.ts` pins the real load path required by [docs/testing.md](../../../docs/testing.md).
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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.
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## Model Experience
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Indirectly, through Code Mode in [`dsh-tools`](../../core/tools/README.md), which renders the exact outer value when it fits or an explicit `invalid-output` / `output-limit` failure. Only the outer `run_code` result enters model context and its ordinary spill policy; binding traffic and intermediate values remain execution-local.
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#### KV Cache effect
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No direct invalidation; the named consumer owns any request-prefix changes.
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## Known Limitations and Deferred Work
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- **OS processes a program spawns survive termination** — `worker.terminate()` ends the thread only, weaker than bash-local's process-group kill; orphan cleanup is a deployment concern until a container backend exists.
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- **Type-strip rides Node's experimental `stripTypeScriptTypes` API** — the relied-on behavior is pinned by unit tests, with amaro/sucrase as named drop-in replacements if it shifts.
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- **`computeMs` expiry can overshoot by up to one poll interval** — busy time is sampled every 25 ms (an internal constant, deliberately not config).
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- **Programs get a five-method `console` shim** (`log`/`info`/`warn`/`error`/`debug`) — deliberately not Node's full console surface.
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- **Intermediate binding values have no byte cap** — a program can exhaust process or worker memory with a value that never becomes outer output.
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- **The 64 MiB default is a rejection boundary, not recoverable storage** — outer spill can save only the bounded logs and diagnostic returned after `output-limit`; bytes rejected beyond the runtime cap never reach the spill layer.
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