Persistent PTY Sessions
Types shared by PTY backends, ctx.terminals, and the model-facing consumer. The persistent PTY Agent Note owns the rationale; this page records the cross-package vocabulary from packages/terminal/terminal/src/types.ts.
Identity and readiness
TerminalSessionId is a service-minted branded id. Optional names are owner-local display metadata; authorization compares the exact owning Agent, not a name or guessed id.
TerminalWaitReason says why one send returned. It is independent from TerminalSessionStatus: silence or timeout may return while the top-level shell remains alive, while session_exit means that shell exited rather than an arbitrary foreground child.
/** Why one interactive send returned control to its caller. */
type TerminalWaitReason = 'stdin_read' | 'inferred_idle' | 'timeout' | 'session_exit'/** Top-level PTY process status, independent of a send's wait reason. */
type TerminalSessionStatus =
| { kind: 'running' }
| { kind: 'exited'; exitCode: number | null; signal: NodeJS.Signals | null }Backend and live session
A backend owns how one registered type starts and detects readiness. TerminalSessionService publishes the returned session only after setup succeeds, then owns id authorization and cleanup. A backend that cannot clean partial startup resources rejects with TerminalBackendCleanupError, allowing disposal to retain the cleanup failure without replacing the caller's cancellation reason. A backend session owns terminal state and captured-resource quiescence.
/** Replaceable provider for one PTY session type. */
interface TerminalBackend {
/** Stable type selected by {@link TerminalSpawnRequest.type}. */
readonly type: string
/** Create an unpublished session or reject after cleaning partial resources; cleanup failure uses {@link TerminalBackendCleanupError}. */
spawn(spec: TerminalBackendSpawnSpec): Promise<TerminalBackendSession>
}/** Backend-owned live session retained by {@link TerminalSessionService}. */
interface TerminalBackendSession {
/** Initial bounded terminal output returned from `terminal_open`. */
readonly motd: string
/** Top-level process id when one exists. */
readonly pid?: number
/** Start one exclusive send operation. */
startSend(request: TerminalSendRequest): TerminalSendOperation
/** Read one bounded page from retained scrollback. */
read(request: TerminalReadRequest): TerminalReadResult
/** Signal the verified foreground process group. */
signal(signal: TerminalSignal): Promise<TerminalSignalResult>
/** Observe top-level process status. */
status(): TerminalSessionStatus
/** Idempotently close the captured owned process tree and await quiescence. */
close(reason: string): Promise<void>
}Send and retained output
One live session accepts one active send. Its operation exposes a consuming output cursor for generic background jobs and one terminal result for a foreground caller. TerminalReadResult separately pages the bounded session scrollback.
/** Live backend-owned send; exactly one may be active per PTY session. */
interface TerminalSendOperation {
/** Resolves after readiness, timeout, cancellation, or top-level process exit. */
done: Promise<TerminalSendResult>
/** Consume output produced since the prior call. */
readOutput(): TerminalSendRead
/** Request `SIGINT`; returns false after the operation settled. */
cancel(): boolean
}/** Settled result for one foreground or background send. */
interface TerminalSendResult {
/** Bounded rendered terminal delta remaining at settlement. */
viewport: string
/** Why the wait returned; this does not imply arbitrary child-process exit. */
waitReason: TerminalWaitReason
/** Top-level session status observed at settlement. */
sessionStatus: TerminalSessionStatus
/** Whether output was dropped from the operation or retained scrollback. */
truncated: boolean
}Ownership and durability
TerminalSessionService attaches one awaited cleanup to the exact owner scope, rejects foreign operations, and keeps sessions alive across backend or tool-plugin reload. PTY state and raw bytes remain process-local. Model input and bounded returned output are durable through the existing tool/call, tool/result, and task-result paths rather than duplicate PTY session events.
Cordis API
Generated from source by scripts/gen-cordis-catalog.ts (verified fresh by pnpm run verify-cordis-catalog in doc-sync; regenerate with pnpm run gen-cordis-catalog) — this section is byte-identical in both language sides of the page. Signature blocks use a ts cordis-catalog fence and keep the original source JSDoc; dispatch modes are defined in the primer, and the framework-inherited ctx API lives in cordis-api/inherited.md.
ctx.terminals — TerminalSessionService
In-process registry for replaceable PTY backends and exact-Agent sessions.
/**
* Register one backend type for this effect scope.
* @param backend - provider with a non-empty unique type.
* @returns disposer that removes exactly this contribution.
*/
registerBackend(backend: TerminalBackend): () => void
/**
* List registered backend types in registration order.
* @returns fresh backend type names.
*/
listBackends(): string[]
/**
* Create and publish one owner-scoped session after backend setup succeeds.
* @param owner - exact registered Agent that owns access and cleanup.
* @param request - backend type plus optional owner-local name and cwd.
* @param signal - cancellation of unpublished setup.
* @returns published identity, metadata, status, and MOTD.
*/
async spawn(owner: Agent, request: TerminalSpawnRequest, signal?: AbortSignal): Promise<TerminalSpawnResult>
/**
* Test whether an exact owner has a published session or unpublished spawn.
* @param owner - exact live owner to inspect.
* @returns true across the entire spawn-to-close interval, with no publication gap.
*/
hasOwnerActivity(owner: Agent): boolean
/**
* Start one exclusive interactive send.
* @param owner - exact session owner.
* @param id - target PTY identity.
* @param request - explicit text, submit behavior, and cancellation.
* @returns live operation handle for foreground await or task registration.
*/
startSend(owner: Agent, id: TerminalSessionId, request: TerminalSendRequest): TerminalSendOperation
/**
* Read one bounded scrollback page from an owned session.
* @param owner - exact session owner.
* @param id - target PTY identity.
* @param request - optional newest-relative offset and line count.
* @returns bounded retained text and pagination metadata.
*/
read(owner: Agent, id: TerminalSessionId, request: TerminalReadRequest = {}): TerminalReadResult
/**
* Deliver an allowed signal through an owned backend session.
* @param owner - exact session owner.
* @param id - target PTY identity.
* @param signal - allowed POSIX signal name.
* @returns delivered foreground process-group identity.
*/
signal(owner: Agent, id: TerminalSessionId, signal: TerminalSignal): Promise<TerminalSignalResult>
/**
* Close one owned session and remove it only after quiescent backend cleanup.
* @param owner - exact session owner.
* @param id - target PTY identity.
* @param reason - diagnostic cleanup reason.
* @returns true for a newly closed session, false when the same close is already in flight.
*/
async kill(owner: Agent, id: TerminalSessionId, reason: string = 'model request'): Promise<boolean>
/**
* List fresh snapshots for exactly one owner.
* @param owner - exact owner whose sessions are visible.
* @returns owner-visible snapshots in publication order.
*/
list(owner: Agent): TerminalSessionSnapshot[]Types: Agent