4.4 KiB
dsh-timeout
The timing-and-classification half of a timeout — a zero-dependency library of pure functions (no runtime harness deps) shared by every capability that clamps a caller's timeout hint, arms a deadline, and later has to tell "timed out" apart from "cancelled".
It owns no termination. The signal it hands out only notifies; actually stopping the work stays in each capability, because that mechanism differs — bash SIGKILLs an OS process group, web tears down a fetch socket — and no shared layer can own all of them. This is the boundary the RFC draws: share the timing/classification, keep the hard kill local.
It is a library, not a service or plugin: no ctx, registers nothing, holds no state, emits no events. A "timeout service" would have to understand how to stop every capability's work — exactly the knowledge a microkernel keeps out of shared layers.
Model Experience
| Context surface | What the model sees | Token effect |
|---|---|---|
| None directly | This library only creates and classifies abort signals. It registers no prompt, schema, or message; consumers decide whether a timeout becomes a marker, a structured error, or no model-visible change. | Zero direct tokens. It can indirectly cap or replace a consumer's result when that consumer renders a timeout. |
Surface
import { clampTimeout, deadline, timeoutOf, TimeoutReason } from '@deepseek-ai/dsh-timeout'
| Export | Role |
|---|---|
clampTimeout(requested, def, max, name?) |
Validate the caller's optional positive-finite hint, fill from def, cap at max. Throws (with name) on a non-positive/non-finite hint. |
deadline(upstream, timeoutMs, code) |
Fuse upstream cancellation with a timeout into one AbortSignal (AbortSignal.any); the timeout carries a TimeoutReason. [Symbol.dispose] clears the timer. |
timeoutOf(signal | { reason }, code?) |
Recover the TimeoutReason from an aborted signal/error, else undefined — the timeout-vs-cancel classifier. Pass code to match only THIS deadline's timer (see nesting below). |
TimeoutReason |
The internal reason (code + timeoutMs) stamped on a timeout abort. Not a public error — providers translate it into their own error/field. |
The timeoutMs <= 0 sentinel
0 is the internal "no timeout" value for backend-owned background work (bash start()): deadline() arms no timer and forwards only upstream; with no upstream either, it returns a never-aborting signal plus a no-op disposer, so every caller keeps one call shape. External request hints validate as positive finite via clampTimeout before they reach deadline, so 0 is never a model-/plugin-facing "disable timeout" value.
Usage shape
// Scope-lifetime consumer (foreground bash, one fetch): `using` disposes the timer.
using d = deadline(upstream, timeoutMs, 'BASH_TIMEOUT')
const outcome = await runWork({ signal: d.signal }) // work listens on d.signal and terminates itself
const timedOut = timeoutOf(d.signal, 'BASH_TIMEOUT') !== undefined // classify the first abort, scoped to OUR code
const aborted = d.signal.aborted && !timedOut // mutually exclusive: timeout won, or cancel did
The signal only notifies — the caller MUST attach its own termination (d.signal.addEventListener('abort', kill), or hand d.signal to fetch). Racing a promise against a timer would resolve the tool-call while the child process or socket leaks on; handing out a signal forces a real termination path to exist.
Pass your own code to timeoutOf so classification composes under nesting: when the upstream you were handed is itself a deadline signal (a future tools/execute middleware arming a per-call deadline), AbortSignal.any preserves the outer TimeoutReason if the outer timer fires first. Scoping to your code makes a foreign timeout read as an ordinary upstream cancel — the correct classification from your capability's view — instead of your own timeout firing when your local timer never expired.
What does NOT get a timeout
Local file read/write/edit take no timeoutMs: a syscall is best-effort-abortable at most, a timeout could not force fsync/rename to stop, and adding one would be an implicit default that violates explicit-over-implicit. See fs/.