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deepseek-harness/packages/client/runtime/src/client/session-history/source.ts
T

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TypeScript

import type {
HistoryEntry, IApiClient, MuxFrame, RpcError, SessionId,
} from '@deepseek-ai/dsh-client-connection/client'
import type { SessionEvent } from '@deepseek-ai/dsh-session/types'
import { transportError } from '@deepseek-ai/dsh-host-apiproxy/api'
import type {
SessionHistoryFace, SessionHistorySnapshot,
} from '../contract/session-history.ts'
import { createHistoryInspection } from '../sessions/history.ts'
import { Notifier } from '../sessions/notifier.ts'
import { PartialAccumulator } from '../sessions/partial.ts'
const HISTORY_PAGE_MESSAGES = 50
function isAborted(signal: AbortSignal | undefined): boolean {
return signal?.aborted === true
}
/** Independent raw-history owner used only by inspection consumers. */
export class SessionHistorySource implements SessionHistoryFace {
private entries: readonly HistoryEntry[] = []
private baseSeq = 0
private hasMore = false
private state: SessionHistorySnapshot['state'] = 'cold'
private error: RpcError | null = null
private generation = 0
private persistentConsumer = false
private readonly consumerSignals = new Set<AbortSignal>()
private openPromise: Promise<void> | null = null
private olderPromise: Promise<void> | null = null
private stitching = false
private liveBuffer: HistoryEntry[] = []
private subscribedLastSeq: number | null = null
private inspectionCache: {
entries: readonly HistoryEntry[]
value: SessionHistorySnapshot['inspection']
} | null = null
private streamPublishToken: object | null = null
private streamBaseInspection: SessionHistorySnapshot['inspection'] | null = null
private streamPartial: PartialAccumulator | null = null
private snapshotCache: SessionHistorySnapshot
private readonly notifier = new Notifier(() => {
this.snapshotCache = this.buildSnapshot()
})
/**
* @param sessionId - Host session identity.
* @param api - Shared wire client.
*/
constructor(
readonly sessionId: SessionId,
private readonly api: IApiClient,
) {
this.snapshotCache = this.buildSnapshot()
}
/**
* Subscribe to ledger changes.
* @param listener - Change callback.
* @returns Unsubscribe function.
*/
subscribe(listener: () => void): () => void {
return this.notifier.subscribe(listener)
}
/**
* Read the cached ledger snapshot.
* @returns Stable snapshot until the source changes.
*/
getSnapshot(): SessionHistorySnapshot {
this.notifier.ensureFresh()
return this.snapshotCache
}
/**
* Load the tail and exhaust all available older pages.
* @param signal - Consumer lifetime.
* @returns When paging completes, fails to advance, or is aborted.
*/
async loadAll(signal?: AbortSignal): Promise<void> {
if (signal?.aborted === true) return
this.trackConsumer(signal)
await this.open()
while (
!isAborted(signal)
&& this.state === 'ready'
&& this.hasMore
) {
const previousBaseSeq = this.baseSeq
await this.loadOlder()
if (isAborted(signal) || this.baseSeq === previousBaseSeq) return
}
}
/** Rebuild and page for whichever mounted consumers survive a reconnect. */
private async loadForConsumers(): Promise<void> {
await this.open()
while (
this.hasConsumer()
&& this.state === 'ready'
&& this.hasMore
) {
const previousBaseSeq = this.baseSeq
await this.loadOlder()
if (!this.hasConsumer() || this.baseSeq === previousBaseSeq) return
}
}
/**
* Route a relevant mux frame without involving the Chat session.
* @param frame - Session-addressed frame.
*/
handleMuxFrame(frame: MuxFrame): void {
if (frame.type === 'session/subscribed') {
this.subscribedLastSeq = frame.lastSeq
return
}
if (frame.type !== 'session/event') return
this.acceptLive({ event: frame.event, ...(frame.view === undefined ? {} : { view: frame.view }) })
}
/** Invalidate dead-generation requests while retaining the last readable snapshot. */
handleDisconnected(): void {
this.generation++
this.openPromise = null
this.olderPromise = null
this.stitching = false
this.liveBuffer = []
this.subscribedLastSeq = null
if (this.state !== 'cold') {
this.state = 'cold'
this.error = null
this.publishDirtyNow()
}
}
/** Rebuild an activated ledger from the new connection generation. */
resync(): void {
if (!this.hasConsumer()) return
this.generation++
this.openPromise = null
this.olderPromise = null
this.stitching = false
this.liveBuffer = []
this.subscribedLastSeq = null
this.entries = []
this.baseSeq = 0
this.hasMore = false
this.state = 'cold'
this.error = null
this.publishDirtyNow()
void this.loadForConsumers()
}
/** Stop future refresh work after the host removes the session. */
dispose(): void {
this.persistentConsumer = false
this.consumerSignals.clear()
this.generation++
this.openPromise = null
this.olderPromise = null
this.liveBuffer = []
this.streamPublishToken = null
this.streamBaseInspection = null
this.streamPartial = null
}
private open(): Promise<void> {
if (this.state === 'ready') return Promise.resolve()
if (this.openPromise !== null) return this.openPromise
const generation = this.generation
const operation = this.doOpen(generation)
const settled = operation.finally(() => {
if (this.openPromise === settled) this.openPromise = null
})
this.openPromise = settled
return settled
}
private trackConsumer(signal: AbortSignal | undefined): void {
if (signal === undefined) {
this.persistentConsumer = true
return
}
if (this.consumerSignals.has(signal)) return
this.consumerSignals.add(signal)
signal.addEventListener('abort', () => {
this.consumerSignals.delete(signal)
}, { once: true })
}
private hasConsumer(): boolean {
return this.persistentConsumer || this.consumerSignals.size > 0
}
private async doOpen(generation: number): Promise<void> {
this.state = 'loading'
this.error = null
this.publishDirtyNow()
try {
let { result } = await this.api.sessions.history({
sessionId: this.sessionId,
maxMessages: HISTORY_PAGE_MESSAGES,
})
if (generation !== this.generation) return
if (!result.ok) {
this.state = 'error'
this.error = result.error
return
}
this.installTail(result.value.events, result.value.hasMore, true)
const tailSeq = this.tailSeq()
if (
this.subscribedLastSeq !== null
&& tailSeq !== null
&& this.subscribedLastSeq > tailSeq
) {
result = (await this.api.sessions.history({
sessionId: this.sessionId,
maxMessages: HISTORY_PAGE_MESSAGES,
})).result
if (generation !== this.generation) return
if (result.ok) this.installTail(result.value.events, result.value.hasMore, true)
}
this.state = 'ready'
} catch (error) {
if (generation !== this.generation) return
this.state = 'error'
const folded = transportError<never>(error)
/* v8 ignore next -- transportError always returns the error branch. */
this.error = folded.ok ? null : folded.error
} finally {
if (generation === this.generation) this.publishDirtyNow()
}
}
private loadOlder(): Promise<void> {
if (this.olderPromise !== null) return this.olderPromise
if (this.state !== 'ready' || !this.hasMore) return Promise.resolve()
const generation = this.generation
const operation = (async () => {
try {
const { result } = await this.api.sessions.history({
sessionId: this.sessionId,
beforeSeq: this.baseSeq,
maxMessages: HISTORY_PAGE_MESSAGES,
})
if (generation !== this.generation || this.state !== 'ready' || !result.ok) return
const older = result.value.events
if (older.length === 0) {
this.hasMore = result.value.hasMore
return
}
const tail = older.at(-1)
if (tail === undefined || tail.event.seq + 1 !== this.baseSeq) {
console.error(
`[web-runtime] inspection history page discontinuous: tail seq ${tail?.event.seq} vs baseSeq ${this.baseSeq}`,
)
this.hasMore = false
return
}
this.entries = [...older, ...this.entries]
this.baseSeq = older[0]?.event.seq ?? this.baseSeq
this.hasMore = result.value.hasMore
} catch (error) {
console.error('[web-runtime] inspection history paging failed:', error)
}
})()
const settled = operation.finally(() => {
if (this.olderPromise !== settled) return
this.olderPromise = null
this.publishDirtyNow()
})
this.olderPromise = settled
return settled
}
private installTail(
tail: readonly HistoryEntry[],
hasMore: boolean,
replace: boolean,
): void {
if (replace) {
this.entries = [...tail]
this.hasMore = hasMore
} else {
const firstSeq = tail[0]?.event.seq
const prefix = firstSeq === undefined
? this.entries
: this.entries.filter(entry => entry.event.seq < firstSeq)
this.entries = [...prefix, ...tail]
}
this.baseSeq = this.entries[0]?.event.seq ?? 0
const buffered = this.liveBuffer
this.liveBuffer = []
for (const entry of buffered) this.appendLive(entry)
this.publishDirtyNow()
}
private acceptLive(entry: HistoryEntry): void {
if (this.state === 'loading' || this.stitching) {
this.liveBuffer.push(entry)
return
}
if (this.state !== 'ready') return
const tailSeq = this.tailSeq()
if (tailSeq !== null && entry.event.seq > tailSeq + 1) {
this.liveBuffer.push(entry)
void this.repairGap()
return
}
if (
entry.event.type === 'assistant/chunk'
&& entry.event.data.chunk.type !== 'usage'
) {
if (!this.appendIncrementalChunk(entry, entry.event)) return
this.publishStreamDirty()
return
}
this.appendLive(entry)
this.publishDirtyNow()
}
private appendLive(entry: HistoryEntry): void {
const tailSeq = this.tailSeq()
if (tailSeq !== null && entry.event.seq <= tailSeq) return
this.entries = [...this.entries, entry]
}
/** Append a chunk against the cached finalized projection; false means no visible publish. */
private appendIncrementalChunk(
entry: HistoryEntry,
event: SessionEvent<'assistant/chunk'>,
): boolean {
const { turn, step, chunk } = event.data
if (!isVisibleAssistantChunk(chunk.type)) {
const inspection = this.currentInspection()
this.appendLive(entry)
this.inspectionCache = { entries: this.entries, value: inspection }
return false
}
const base = this.streamBaseInspection ?? this.currentInspection()
this.streamBaseInspection = base
if (
this.streamPartial === null
|| this.streamPartial.turn !== turn
|| this.streamPartial.step !== step
) {
const current = base.partial
this.streamPartial = new PartialAccumulator(
turn,
step,
current?.turn === turn && current.step === step ? current.blocks : [],
)
}
this.streamPartial.push(chunk)
this.appendLive(entry)
this.inspectionCache = {
entries: this.entries,
value: { ...base, partial: this.streamPartial.toPartial() },
}
return true
}
/** Coalesce token-stream projection and rendering work to one publish per browser frame. */
private publishStreamDirty(): void {
if (this.streamPublishToken !== null) return
const token = {}
this.streamPublishToken = token
const publish = () => {
if (this.streamPublishToken !== token) return
this.streamPublishToken = null
this.notifier.markDirty()
}
if (typeof globalThis.requestAnimationFrame === 'function') {
globalThis.requestAnimationFrame(publish)
} else {
queueMicrotask(publish)
}
}
/** Publish structural changes immediately and invalidate an older scheduled stream publish. */
private publishDirtyNow(): void {
this.streamPublishToken = null
this.streamBaseInspection = null
this.streamPartial = null
this.notifier.markDirty()
}
private async repairGap(): Promise<void> {
if (this.stitching) return
this.stitching = true
const generation = this.generation
try {
const { result } = await this.api.sessions.history({
sessionId: this.sessionId,
maxMessages: HISTORY_PAGE_MESSAGES,
})
if (result.ok && generation === this.generation && this.state === 'ready') {
this.installTail(result.value.events, result.value.hasMore, false)
}
} catch (error) {
console.error('[web-runtime] inspection history gap repair failed:', error)
} finally {
if (generation === this.generation) this.stitching = false
}
}
private tailSeq(): number | null {
return this.entries.at(-1)?.event.seq ?? null
}
private buildSnapshot(): SessionHistorySnapshot {
return {
state: this.state,
error: this.error,
hasMore: this.hasMore,
inspection: this.currentInspection(),
}
}
/** Inspection pinned to the source's current immutable entry array. */
private currentInspection(): SessionHistorySnapshot['inspection'] {
if (this.inspectionCache?.entries !== this.entries) {
const entries = this.entries
this.inspectionCache = {
entries,
value: createHistoryInspection(() => entries),
}
}
return this.inspectionCache.value
}
}
function isVisibleAssistantChunk(type: string): boolean {
return type === 'block-start'
|| type === 'text-delta'
|| type === 'reasoning-delta'
|| type === 'tool-call-delta'
|| type === 'block-end'
}