@tanstack/ai-sandbox
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Provider-agnostic sandbox layer for TanStack AI — run harness adapters inside isolated sandboxes (defineSandbox, defineWorkspace, withSandbox) with a uniform SandboxHandle, workspace bootstrap, policy, and resumable lifecycle.
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TypeScript
import { InternalLogger } from '@tanstack/ai/adapter-internals';
import { StreamChunk, StreamDurability } from '@tanstack/ai';
/**
* Default bound on consecutive stored chunks alignment will skip as out-of-band.
*
* A bound is what keeps this a tolerance rather than a search. Unbounded, a
* genuine determinism regression would make alignment scan forward through the
* whole log looking for a fingerprint that happens to match, suppress
* everything it passed, and deliver a stream whose prefix and suffix disagree —
* the exact failure {@link JournalReplayDivergedError} exists to prevent. 64 is
* well above any realistic burst of bridged console events between two
* translated chunks and well below a log length where a false match becomes
* plausible.
*/
export declare const DEFAULT_MAX_OUT_OF_BAND_SKIP = 64;
/**
* The out-of-band predicate for the harness adapters.
*
* `ai-codex` and `ai-claude-code` splice `createBridgeEventChannel`'s stream
* into their translated output with `mergeChunkStreams`. That channel is the
* only producer on the path and it emits exclusively `EventType.CUSTOM` chunks
* (`bridge-events.ts:53-63`), fired by LIVE bridged-tool execution. A replay
* runs no tools, so those chunks exist in the log and not in the replay.
*
* Structural rather than a list of event names on purpose: a new bridged tool
* inventing a new `name` must not silently reintroduce the divergence.
*/
export declare function isBridgeCustomChunk(chunk: StreamChunk): boolean;
/**
* The replay produced a different chunk than the log already holds at that
* index. Means translation stopped being deterministic — a `genId` that is not
* run-scoped, a translator that consults the clock, or a journal that was
* rewritten. Fail loud: suppressing the mismatch would deliver a stream whose
* prefix and suffix disagree about message identity.
*/
export declare class JournalReplayDivergedError extends Error {
readonly index: number;
readonly stored: string;
readonly replayed: string;
constructor(index: number, stored: string, replayed: string);
}
/**
* The replay reproduced the stored chunk EXACTLY except for its `threadId`.
*
* A distinct diagnosis because the cause and the fix are entirely different from
* a real divergence. The caller's `threadId` lands in every emitted chunk — so
* an attach route that passes a different `threadId` than the run record's
* fails alignment at the very first chunk (`RUN_STARTED`). The agent behaved
* identically; only the id moved. Reported as a
* generic divergence, that sends the reader hunting for non-determinism in the
* translator, which is the wrong place entirely.
*
* A SUBCLASS of {@link JournalReplayDivergedError}, deliberately: this is still a
* divergence and still fatal, so a consumer already branching on the general
* class keeps working. The two are not collapsed — a genuine content divergence
* throws the base class, so `instanceof JournalReplayThreadIdMismatchError`
* separates a config mistake from a determinism bug in exactly one check.
*/
export declare class JournalReplayThreadIdMismatchError extends JournalReplayDivergedError {
readonly storedThreadId: string | undefined;
readonly replayedThreadId: string | undefined;
constructor(index: number, stored: string, replayed: string, storedThreadId: string | undefined, replayedThreadId: string | undefined);
}
export interface AlignToStoredLogOptions<TOffset extends string = string> {
/**
* The run's event log. Read from the beginning; never written here.
*
* Generic in the offset type, defaulted to `string`, for the same reason
* {@link RunDeps} is: a branded-cursor backend's `StreamDurability<TOffset>`
* is not assignable to `StreamDurability<string>`.
*
* Narrowed to `snapshot` — the only member this transform touches, as the
* function docs below spell out — so the capability-bus view of a log
* (`SandboxDurabilityLog`, which omits the offset-invariant `read`) can be
* passed straight through by `alignedIfAttaching`. A full `StreamDurability`
* still satisfies it, so no existing caller changes.
*/
durability: Pick<StreamDurability<TOffset>, 'snapshot'>;
/** Optional sink for the alignment summary. */
logger?: InternalLogger;
/**
* Recognizes a stored chunk that the replay CANNOT reproduce, so alignment
* skips it instead of throwing.
*
* Absent by default, which keeps strict positional comparison: any stored
* chunk the replay does not produce is a determinism bug and fails loudly.
* Pass {@link isBridgeCustomChunk} on the harness attach path, where the
* previous host spliced live bridged-tool events into the log.
*
* The predicate is applied to the STORED chunk, never to the replayed one. A
* skipped entry is suppressed, not re-appended, so the client's view is
* unchanged: it already received that chunk under its own offset.
*/
isOutOfBand?: (chunk: StreamChunk) => boolean;
/**
* Maximum CONSECUTIVE stored chunks that may be skipped as out-of-band before
* alignment gives up. Reset by every match. Defaults to
* {@link DEFAULT_MAX_OUT_OF_BAND_SKIP}. Ignored when `isOutOfBand` is absent.
*/
maxOutOfBandSkip?: number;
}
/**
* Suppress the chunks already present in the event log and yield the rest.
*
* The stored prefix is read exactly once, eagerly, before the first replay
* chunk is pulled. Both halves of that matter:
*
* - **Exactly once**, because a second read mid-stream would race the appends
* the caller is making downstream of this transform and could classify a
* chunk this very run just appended as an already-stored one, dropping it.
* - **Via `snapshot()`, never `read()`**. `read` *tails*: it returns only when
* the log is terminalized with `close()` or the caller aborts. A takeover's
* log is open by definition — the host that would have closed it is the host
* that died — so `for await (… of read('-1'))` would never finish, and on an
* empty log `memoryStream` rejects a from-start join outright once its
* first-chunk deadline elapses. `snapshot()` is the bounded read: it resolves
* with what is stored right now, including while the log is still open, and
* resolves to `[]` for a run with nothing stored.
*/
export declare function alignToStoredLog<TOffset extends string = string>(chunks: AsyncIterable<StreamChunk>, options: AlignToStoredLogOptions<TOffset>): AsyncIterable<StreamChunk>;