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+/**
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+ * Versionless, JSON-lines wire protocol between the Node host and the CPython subprocess. Frames
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+ * travel on the child's fd 3 (one JSON object per line), leaving stdout/stderr free for the
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+ * program's own output. Host treats every inbound frame as hostile because model code can post
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+ * anything through the same fd; the Python bootstrap trusts host replies.
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+ * @module @deepseek-ai/dsh-code-runtime-python/src/protocol
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+ */
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+
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+// The protocol channel is fd 3 from the child's perspective — the host pins it
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+// positionally via `stdio: ['pipe','pipe','pipe','pipe']` (index.ts), and the
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+// Python bootstrap reads the same constant from its own protocol.py.
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+
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+/**
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+ * What the host sends immediately after spawn, as the first line on fd 3. The
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+ * Python bootstrap reads this, applies resource limits, then waits for the
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+ * subsequent run frame. Separated from the run so the run message stays
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+ * pure model input.
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+ */
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+export interface BootMessage {
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+ type: 'boot'
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+ /** RLIMIT_CPU seconds; the Python bootstrap sets this on itself before executing model code. */
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+ cpuSeconds: number
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+ /** RLIMIT_AS bytes; caps address space so a runaway allocation fails cleanly. */
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+ addressSpaceBytes: number
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+ /** Shared byte budget for captured log text (Python-side ledger). */
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+ maxLogBytes: number
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+ /** Byte cap for the rendered completion value. */
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+ maxValueBytes: number
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+ /**
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+ * The namespaces to materialize inside the program (globals + names;
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+ * functions stay host-side). `errorClass` asks the bootstrap to mint a
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+ * program-visible exception class under that global: rejected calls raise
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+ * its instances carrying the member name on `memberNameProperty`.
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+ */
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+ namespaces: { global: string; names: string[]; errorClass?: { name: string; memberNameProperty: string } }[]
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+}
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+
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+// The run request `{ type: 'run', program }` follows BootMessage once the
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+// child acknowledges with `boot-ack`; the host sends it as an inline literal
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+// (it carries only the model's program body — caps and bindings crossed on boot).
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+
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+/** Python → host: acknowledges boot completed and resource limits are in place. */
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+interface BootAckMessage {
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+ type: 'boot-ack'
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+}
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+
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+/** Python → host: one bridged binding call (`await tools.name(args)` inside the program). */
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+interface CallMessage {
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+ type: 'call'
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+ /** Python-issued correlation id; the host answers each id at most once and ignores duplicates. */
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+ id: number
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+ /** The namespace global the call targets. */
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+ global: string
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+ /** The function name within the namespace. */
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+ name: string
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+ /** The JSON-safe argument the model program passed. */
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+ args: unknown
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+}
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+
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+/**
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+ * Python → host: captured text, streamed eagerly so output survives a
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+ * mid-run termination (RLIMIT_CPU, SIGTERM/SIGKILL, host wall-timeout).
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+ */
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+interface LogMessage {
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+ type: 'log'
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+ text: string
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+ /**
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+ * Set when this frame IS the child ledger's truncation marker rather than
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+ * program output. The two ledgers can exhaust at different points — one
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+ * child entry larger than `maxLogBytes` sends only the marker while the host
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+ * ledger is still nearly empty — so the host cannot infer the child's state
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+ * from its own budget, and comparing the text against the marker string
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+ * would also honour a program that printed that string itself. Carrying it
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+ * as a field lets the host stop capturing at the same point the child did
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+ * and keeps exactly one marker in `logs`.
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+ */
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+ truncated?: boolean
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+}
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+
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+/**
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+ * Python → host: the program settled. `error` carries a program exception
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+ * (traceback text), an `invalid-output` (completion value was not lossless
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+ * JSON), or an `output-limit` (serialized completion exceeded the configured
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+ * cap); wall/CPU budgets, aborts, and substrate death are observed host-side.
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+ * `value` is present only on a clean completion that produced one, and crosses
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+ * as exact lossless JSON — never substituted or truncated.
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+ */
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+interface DoneMessage {
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+ type: 'done'
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+ value?: unknown
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+ error?: { kind: 'exception' | 'invalid-output' | 'output-limit'; message: string }
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+}
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+
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+/**
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+ * Every message the Python side sends. The member interfaces stay module-
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+ * private: consumers match on the union's discriminant; the host sends the
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+ * boot and run frames as inline literals.
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+ */
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+export type ChildToHost = BootAckMessage | CallMessage | LogMessage | DoneMessage
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+
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+/** Host → Python: the answer to one {@link CallMessage}. */
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+export type ReplyMessage =
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+ | { type: 'reply'; id: number; ok: true; value: unknown }
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+ | { type: 'reply'; id: number; ok: false; message: string }
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+
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+/**
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+ * The in-band marker text announcing that log capture stopped at the byte
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+ * budget. Shared wire vocabulary: the Python-side LogBuffer emits it when ITS
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+ * ledger exhausts, and the host emits identical text when its own ledger drops
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+ * a frame first (forged fd-3 traffic, stray stdout bytes) — a truncated run
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+ * reads the same however the cap was hit.
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+ * @param maxBytes - the configured `maxLogBytes` the marker names.
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+ * @returns the marker line.
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+ */
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+export function logTruncationMarker(maxBytes: number): string {
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+ return `[dsh-code-runtime-python] log capture truncated at ${maxBytes} bytes`
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+}
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+
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+/**
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+ * Serialize one JSON-parse-produced value without recursion. `JSON.stringify`
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+ * recurses per nesting level and throws `RangeError` a few thousand levels
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+ * deep, but the seam's `CodeJsonValue` has no depth limit — an honest deep
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+ * completion or binding resolution below the byte budget must cross intact
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+ * (the worker backend's wire is equally stack-safe). Callers must pass a value
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+ * produced by `JSON.parse` (or equally JSON-plain): only `null`, finite
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+ * numbers, booleans, strings, dense arrays, and plain objects — this encoder
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+ * validates nothing. Output is byte-identical to compact `JSON.stringify`.
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+ * @param value - a JSON-plain value (e.g. straight from `JSON.parse`).
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+ * @returns the compact JSON encoding.
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+ */
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+export function encodeJsonPlain(value: unknown): string {
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+ type Task = { text: string } | { value: unknown }
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+ const chunks: string[] = []
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+ const tasks: Task[] = [{ value }]
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+ for (let task = tasks.pop(); task !== undefined; task = tasks.pop()) {
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+ if ('text' in task) {
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+ chunks.push(task.text)
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+ continue
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+ }
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+ const current = task.value
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+ if (typeof current === 'string') {
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+ chunks.push(JSON.stringify(current))
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+ } else if (Array.isArray(current)) {
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+ chunks.push('[')
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+ tasks.push({ text: ']' })
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+ for (let index = current.length - 1; index >= 0; index--) {
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+ if (index < current.length - 1) tasks.push({ text: ',' })
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+ tasks.push({ value: current[index] })
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+ }
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+ } else if (typeof current === 'object' && current !== null) {
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+ const record = current as Record<string, unknown>
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+ chunks.push('{')
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+ tasks.push({ text: '}' })
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+ const keys = Object.keys(record)
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+ for (let index = keys.length - 1; index >= 0; index--) {
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+ const key = keys[index] as string
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+ if (index < keys.length - 1) tasks.push({ text: ',' })
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+ tasks.push({ value: record[key] })
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+ tasks.push({ text: `${JSON.stringify(key)}:` })
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+ }
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+ } else {
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+ chunks.push(scalarJson(current))
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+ }
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+ }
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+ return chunks.join('')
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+}
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+
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+/**
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+ * One scalar (null, boolean, finite number) as JSON text. A beyond-safe-range
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+ * integral double needs BigInt digits: `String(2 ** 60)` emits the ROUNDED
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+ * `...847000` form, and echoing that to the child would silently change the
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+ * integer the seam promised to carry losslessly — `BigInt(2 ** 60)` prints the
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+ * exact `...846976` the double actually holds.
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+ * @param current - a JSON-plain scalar (JSON.parse emits nothing else).
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+ * @returns its JSON encoding.
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+ */
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+function scalarJson(current: unknown): string {
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+ if (typeof current === 'number' && Number.isInteger(current) && !Number.isSafeInteger(current)) {
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+ return BigInt(current).toString()
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+ }
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+ return String(current)
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+}
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+
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+/**
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+ * Meter a forged done value's compact-JSON byte length AND its number
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+ * losslessness in one bounded traversal, stopping the instant `maxBytes` is
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+ * crossed. A forged `done.value` arrives straight off fd 3 and can sit anywhere
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+ * below the 256 MiB frame ceiling while `maxValueBytes` defaults to 32 KiB. The
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+ * previous split — an unbounded `hasNonLosslessNumber` scan in
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+ * {@link validateChildFrame} followed by a separate byte meter — pushed every
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+ * member of a wide flat payload onto a scan stack before any cap check ran, so
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+ * a below-ceiling forgery could still force a hundreds-of-megabytes host
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+ * allocation. Folding both jobs here rejects over-budget BEFORE enqueuing an
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+ * array's or object's children, keeping the traversal O(cap). A non-lossless
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+ * number (non-finite, negative zero) is caught only when the value fits the
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+ * budget — an over-budget value is rejected regardless, so the distinction is
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+ * moot. Same JSON-plain precondition and traversal shape as
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+ * {@link encodeJsonPlain}; per-scalar encoding delegates to `JSON.stringify`.
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+ * @param value - a JSON-plain value (e.g. straight from `JSON.parse`).
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+ * @param maxBytes - the completion-value budget in bytes.
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+ * @returns `{ ok: true, bytes }` with the exact serialized size, or
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+ * `{ ok: false, reason }` — `over-budget` once the size exceeds `maxBytes`,
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+ * `non-lossless` on a non-finite or negative-zero number.
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+ */
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+export function checkDoneValue(value: unknown, maxBytes: number): { ok: true; bytes: number } | { ok: false; reason: 'over-budget' | 'non-lossless' } {
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+ let bytes = 0
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+ const stack: unknown[] = [value]
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+ while (stack.length > 0) {
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+ const current = stack.pop()
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+ if (typeof current === 'number') {
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+ if (!Number.isFinite(current) || Object.is(current, -0)) return { ok: false, reason: 'non-lossless' }
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+ bytes += Buffer.byteLength(scalarJson(current), 'utf8')
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+ } else if (typeof current === 'string') {
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+ // Lower-bound BEFORE materializing the escaped form: every UTF-16 code
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+ // unit is at least one UTF-8 byte plus the two quotes, so a huge or
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+ // control-heavy forged string (whose escaped copy expands severalfold)
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+ // is rejected without allocating that copy.
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+ if (bytes + current.length + 2 > maxBytes) return { ok: false, reason: 'over-budget' }
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+ bytes += Buffer.byteLength(JSON.stringify(current), 'utf8')
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+ } else if (Array.isArray(current)) {
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+ // Brackets plus one comma per gap; elements add themselves. Reject
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+ // BEFORE enqueuing children: every element serializes to at least one
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+ // byte, so a forged flat array below the frame ceiling but far above
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+ // the budget fails here without growing the host stack by millions of
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+ // entries first.
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+ bytes += 2 + (current.length > 1 ? current.length - 1 : 0)
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+ if (bytes + current.length > maxBytes) return { ok: false, reason: 'over-budget' }
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+ for (const item of current) stack.push(item)
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+ } else if (typeof current === 'object' && current !== null) {
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+ const record = current as Record<string, unknown>
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+ // Count own keys WITHOUT Object.entries/Object.keys: either would
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+ // allocate one slot (entries: one pair array) per member before the
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+ // bound below could run, recreating the spike the bound exists to stop.
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+ let count = 0
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+ for (const key in record) if (Object.hasOwn(record, key)) count += 1
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+ bytes += 2 + (count > 1 ? count - 1 : 0)
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+ // Same pre-enqueue bound: each entry contributes its quoted key (>= 2
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+ // bytes), the colon, and a >= 1-byte value.
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+ if (bytes + count * 4 > maxBytes) return { ok: false, reason: 'over-budget' }
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+ for (const key in record) {
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+ if (!Object.hasOwn(record, key)) continue
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+ // The same string lower bound, before escaping the key.
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+ if (bytes + key.length + 3 > maxBytes) return { ok: false, reason: 'over-budget' }
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+ bytes += Buffer.byteLength(JSON.stringify(key), 'utf8') + 1
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+ stack.push(record[key])
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+ }
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+ } else {
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+ bytes += Buffer.byteLength(scalarJson(current), 'utf8')
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+ }
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+ if (bytes > maxBytes) return { ok: false, reason: 'over-budget' }
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+ }
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+ return { ok: true, bytes }
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+}
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+
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+/**
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+ * Whether a raw JSON line contains an integer token that would lose precision
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+ * as a JavaScript number. `JSON.parse` silently rounds such a token
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+ * (`9007199254740993` becomes `...992`) BEFORE any validation can see it, so
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+ * the check must read the source text; a beyond-safe-range token whose double
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+ * parse round-trips exactly (`2**53`, `2**60`) is lossless and passes. The scan walks the line skipping string literals (a digit run
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+ * inside a string is data, not a number token) and tests every number token
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+ * in plain integer form — no fraction or exponent, which parse as doubles by
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+ * intent. A reviver cannot do this job: the reviver walk recurses per nesting
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+ * level and would reintroduce the depth limit `encodeJsonPlain` removes.
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+ * @param line - the raw UTF-8 text of one JSON-lines frame.
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+ * @returns true when an unsafe integer token is present outside strings.
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+ */
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+export function hasUnsafeIntegerToken(line: string): boolean {
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+ for (let index = 0; index < line.length; index++) {
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+ const char = line[index]
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+ if (char === '"') {
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+ // Skip the string literal, honoring backslash escapes.
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+ for (index++; index < line.length; index++) {
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+ if (line[index] === '\\') index++
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+ else if (line[index] === '"') break
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+ }
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+ continue
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+ }
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+ if (char === '-' || (char !== undefined && char >= '0' && char <= '9')) {
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+ let end = index + 1
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+ while (end < line.length) {
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+ const c = line[end] as string
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+ if ((c >= '0' && c <= '9') || c === '.' || c === 'e' || c === 'E' || c === '+' || c === '-') end++
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+ else break
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+ }
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+ const token = line.slice(index, end)
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+ // Beyond the safe range an integer token is still lossless IFF the
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+ // double parse round-trips exactly (2**53 does; 2**53+1 rounds) — the
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+ // canonical boundary accepts every JS-double-exact value, so only a
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+ // genuinely rounding token marks the frame as forged.
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+ if (/^-?\d+$/.test(token)) {
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+ const parsed = Number(token)
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+ // A token that parses to Infinity is trivially lossy; a finite
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+ // beyond-safe-range one is lossy only when the BigInt round-trip
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+ // disagrees.
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+ if (!Number.isFinite(parsed)) return true
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+ if (!Number.isSafeInteger(parsed) && BigInt(token) !== BigInt(parsed)) return true
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+ }
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+ index = end - 1
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+ }
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+ }
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+ return false
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+}
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+
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+/**
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+ * Lazily yield one plain object's own enumerable property values. A generator
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+ * (not `Object.values`/`Object.entries`) because {@link hasNonLosslessNumber}
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+ * traverses breadth it cannot bound: those helpers copy the whole member list
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+ * up front, so a wide forged object would cost a second full-breadth
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+ * allocation before a single value is examined.
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+ * @param record - a JSON-parse-produced object.
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+ * @yields each own enumerable property value, in key order.
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+ */
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+function* ownValues(record: object): Generator {
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+ for (const key in record) {
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+ if (Object.hasOwn(record, key)) yield (record as Record<string, unknown>)[key]
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+ }
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+}
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+
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+/**
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+ * Whether a JSON.parse-produced value contains a number outside lossless
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+ * JSON: non-finite (`1e400` parses to `Infinity`) or negative zero (`-0.0`
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+ * parses to JS `-0`, whose sign bit a re-serialization drops). The honest
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+ * child's validator rejects these before sending, so a frame carrying one is
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+ * forged.
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+ *
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+ * Runs on `call.args`, which — unlike a completion value — has NO seam byte
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+ * cap, so there is no budget to reject a wide payload against the way
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+ * {@link checkDoneValue} does. The traversal therefore holds ONE cursor per
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+ * NESTING LEVEL (an array or {@link ownValues} iterator) instead of one entry
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+ * per member: a forged flat `args` just below the 256 MiB frame ceiling would
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+ * otherwise push tens of millions of stack entries — and `Object.values` would
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+ * copy each object's full breadth — allocating hundreds of megabytes beyond
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+ * what `JSON.parse` already holds. Iterative either way, so a deep frame
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+ * cannot overflow the host stack.
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+ * @param value - a JSON-parse-produced value from an fd-3 frame.
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+ * @returns true when any contained number is non-finite or negative zero.
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+ */
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+export function hasNonLosslessNumber(value: unknown): boolean {
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+ const cursors: Iterator<unknown>[] = [[value].values()]
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+ while (cursors.length > 0) {
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+ // The loop condition guarantees a top cursor.
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+ const cursor = cursors.at(-1) as Iterator<unknown>
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+ const step = cursor.next()
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+ if (step.done === true) {
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+ cursors.pop()
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+ continue
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+ }
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+ const current = step.value
|
|
|
+ if (typeof current === 'number') {
|
|
|
+ if (!Number.isFinite(current) || Object.is(current, -0)) return true
|
|
|
+ } else if (Array.isArray(current)) {
|
|
|
+ cursors.push((current as unknown[]).values())
|
|
|
+ } else if (typeof current === 'object' && current !== null) {
|
|
|
+ cursors.push(ownValues(current))
|
|
|
+ }
|
|
|
+ }
|
|
|
+ return false
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * Runtime shape gate for inbound fd-3 traffic. Model code has full access to
|
|
|
+ * fd 3 and can post anything — `null`, primitives, poisoned fields — so the
|
|
|
+ * compile-time union means nothing here: every field is validated and REBUILT
|
|
|
+ * before the host reads it (forged extras never ride along; a non-number id
|
|
|
+ * can never be echoed into a reply). Junk returns `undefined` and is dropped
|
|
|
+ * so a throw in the host's `message` handler cannot crash the host process.
|
|
|
+ * @param raw - one JSON-parsed frame from fd 3.
|
|
|
+ * @returns the rebuilt frame, or `undefined` to drop it silently.
|
|
|
+ */
|
|
|
+export function validateChildFrame(raw: unknown): ChildToHost | undefined {
|
|
|
+ if (typeof raw !== 'object' || raw === null) return undefined
|
|
|
+ const m = raw as Record<string, unknown>
|
|
|
+ switch (m.type) {
|
|
|
+ case 'boot-ack':
|
|
|
+ return { type: 'boot-ack' }
|
|
|
+ case 'log':
|
|
|
+ if (typeof m.text !== 'string') return undefined
|
|
|
+ // Rebuilt, not passed through: a forged `truncated` of any other type
|
|
|
+ // would reach the host as a truthy value and silence capture for the
|
|
|
+ // rest of the run. Only the literal `true` counts.
|
|
|
+ return { type: 'log', text: m.text, ...m.truncated === true ? { truncated: true } : {} }
|
|
|
+ case 'call': {
|
|
|
+ // The id must be a finite number: it is echoed verbatim into the reply
|
|
|
+ // frame, and a forged `1e400` id (Infinity after JSON.parse) would make
|
|
|
+ // the reply unencodable as strict JSON.
|
|
|
+ if (typeof m.id !== 'number' || !Number.isFinite(m.id) || typeof m.global !== 'string' || typeof m.name !== 'string') return undefined
|
|
|
+ // A forged frame can omit `args` entirely; rebuilding it as `undefined`
|
|
|
+ // would invoke the binding with a non-JSON value, bypassing the
|
|
|
+ // lossless-JSON argument boundary. Any PRESENT value is JSON-plain by
|
|
|
+ // construction (the frame came from JSON.parse), so presence is the
|
|
|
+ // whole check.
|
|
|
+ if (!Object.hasOwn(m, 'args')) return undefined
|
|
|
+ // JSON.parse yields Infinity for 1e400 and preserves -0; both are
|
|
|
+ // outside lossless JSON, and the honest child never sends them.
|
|
|
+ if (hasNonLosslessNumber(m.args)) return undefined
|
|
|
+ return { type: 'call', id: m.id, global: m.global, name: m.name, args: m.args }
|
|
|
+ }
|
|
|
+ case 'done': {
|
|
|
+ // The value passes through untouched here: scanning it for non-lossless
|
|
|
+ // numbers would push every member of a wide forged payload before any
|
|
|
+ // byte cap runs. The done handler's bounded `checkDoneValue` folds the
|
|
|
+ // losslessness check into the metered traversal, rejecting over-budget
|
|
|
+ // before it enqueues children.
|
|
|
+ const err = m.error
|
|
|
+ if (err === undefined) {
|
|
|
+ return m.value === undefined ? { type: 'done' } : { type: 'done', value: m.value }
|
|
|
+ }
|
|
|
+ if (typeof err !== 'object' || err === null) return undefined
|
|
|
+ const { kind, message } = err as Record<string, unknown>
|
|
|
+ if (typeof message !== 'string') return undefined
|
|
|
+ if (kind !== 'exception' && kind !== 'invalid-output' && kind !== 'output-limit') return undefined
|
|
|
+ return m.value === undefined
|
|
|
+ ? { type: 'done', error: { kind, message } }
|
|
|
+ : { type: 'done', value: m.value, error: { kind, message } }
|
|
|
+ }
|
|
|
+ default:
|
|
|
+ return undefined
|
|
|
+ }
|
|
|
+}
|
Chinesezjc