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Host and Client session control: create, resume, prompt, follow history, and project live session state. package-reference

Session Controller

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Summary

@deepseek-ai/dsh-api-session-controller owns the Host ctx.sessionController service and the generated Client session, skills, and fileReferences Remote namespaces. It serves Session lifecycle and history, the Host-generation model catalog, workspace-path opening, user-invocable skill discovery, and the adapter for Agent-scoped file references. Use it through API Gateway when a Client needs operations addressed by a Session.

Table of Contents


Use this package

History pages and follow opening snapshots carry a discriminated SessionHistoryRecord. Both variants use { type, event }: type: 'event' carries one raw SessionWireEvent, while type: 'chunks' carries one lossless ChunkRowEvent for consecutive same-block assistant/chunk deltas. Both inner values expose type, seq, time, and data, so the Client retains each accepted record as one SessionEventLikeEntry without record-by-record conversion. A packed event's seq and time identify its first member, and data retains the fragment and timestamp-gap arrays. Live follow frames remain individual event records. Tool arguments, result content, failures, and tool/result.data.meta pass through unchanged; the controller does not resolve a Tool definition, run a presenter, or attach UI data.

Each endpoint states its activation policy. List, search, attachment, history pages, log following, skill discovery, and workspace-path opening can inspect persistence without activating an Agent; canOpenWorkspacePath() reports native-opening availability without addressing a Session. Queue mutation and cancellation require live state; model, rename, prompt, and file-reference operations may resolve or resume an ordinary Session. Create and fork are the only operations that create a new Agent directly. The skill catalog instead uses a live Agent when present or the recorded preset's standing scope when cold, so listing never starts an Agent.

The Client adapter exposes SessionEventStream, a Gateway RemoteJournalStream bound to one ordinary or direct-subagent address. It opens follow before the initial page, publishes only contiguous replace, prepend, and append changes, and repairs reconnect or sequence gaps through a tail page. Ordinary records cover [event.seq, event.seq]; packed rows cover [event.seq, event.seq + memberCount - 1]. A business, persistence, or unresolved continuity failure terminates the stream, while only physical carrier loss selects automatic resumption. SessionControlStream is a Gateway RemoteSnapshotStream; every generation opens with a complete process-local baseline, so reconnect replaces queue, jobs, and projection state instead of treating transient values as durable events.

The Session object also carries local submission echoes: session.beginSubmission inserts one into SessionSnapshot.pendingSubmissions synchronously, before the caller serializes and prompts, so a conversation UI can show the message on the submit click's own frame. The prompt's requestId is the correlation identity — the Host already echoes it as the durable user source's rpcId, and queue occurrences project it as SessionQueuedItem.rpcId. An echo retires one animation frame after its durable event or queue occurrence is observed (the delay keeps it renderable until the transcript node is), immediately when its identified prompt fails or is abandoned, and as failed on disposal; each retirement fires the registered onRetire callback exactly once. Echoes are Client memory only — reload and reconnect rebuild the conversation from durable events alone.


Configuration

Field Default Meaning
coldBlankProbeMaxBytes 1,024 Maximum physical size of a cold Session artifact eligible for blankness verification; 0 disables probes
nativeOpen platform-detected Whether Session workspace paths can be handed to a native desktop opener

The generated configuration catalog is the exhaustive source for accepted fields and their JSDoc.


Model Experience

None, as invoked Agent commands own any model-visible effect.

KV Cache effect

No direct effect; model requests remain owned by the Agent and LLM packages.

Known Limitations and Deferred Work

  • Control baselines represent process-local state and therefore cannot reconstruct jobs after a Host restart.
  • A failed follow resumption remains visible to the caller instead of retrying indefinitely.
  • File-reference completion uses the shared Agent lookup and can resume a cold Session; the skills/list catalog is the non-activating alternative for skill metadata.

Dev Note

Working context for maintainers — click to expand

None.