1/** Live Session projection state with reconnect baselines. */

2

3import type { Context } from '@deepseek-ai/cordis'

4import { Deque } from '@deepseek-ai/dsh-deque'

5import type {

6 Session, SessionId,

7} from '@deepseek-ai/dsh-session'

8import type { JsonValue } from '@deepseek-ai/dsh-util-values'

9import type {

10 SessionControlBaseline,

11 SessionControlFrame,

12 SessionProjectionBaseline,

13 SessionProjectionValues,

14} from './types.ts'

15

16/** Owns the Host-wide Session control stream. */

17export class SessionControlController {

18 private readonly streams = new Set<ControlQueue>()

19

20 /** @param ctx - Host context carrying live Agent and projection services. */

21 constructor(private readonly ctx: Context) {

22 ctx.sessionProjections.onChanged((session, key, value, seq) => {

23 this.broadcast({

24 type: 'projection',

25 sessionId: session.id,

26 key,

27 value: value as JsonValue,

28 seq,

29 })

30 })

31 ctx.effect(() => () => {

32 for (const stream of this.streams) stream.end()

33 this.streams.clear()

34 }, 'session-controller.control')

35 }

36

37 /**

38 * Open one generation of Host-wide live control state.

39 * @param signal - Remote stream cancellation.

40 * @returns one complete baseline followed by live replacement frames.

41 */

42 async *control(signal: AbortSignal): AsyncIterable<SessionControlFrame> {

43 signal.throwIfAborted()

44 const queue = new ControlQueue()

45 this.streams.add(queue)

46 try {

47 yield { type: 'baseline', value: this.baseline() }

48 yield* queue.iterate(signal)

49 } finally {

50 this.streams.delete(queue)

51 queue.end()

52 }

53 }

54

55 private baseline(): SessionControlBaseline {

56 const sessions = this.ctx.sessions.list()

57 return {

58 projections: this.projectionBaseline(sessions),

59 }

60 }

61

62 private projectionBaseline(

63 sessions: readonly Session[],

64 ): Readonly<Record<SessionId, SessionProjectionBaseline>> {

65 const blocks = Object.create(null) as Record<SessionId, SessionProjectionBaseline>

66 for (const session of sessions) {

67 const snapshot = this.ctx.sessionProjections.snapshot(session)

68 blocks[session.id] = {

69 asOfSeq: snapshot.asOfSeq,

70 // Every projection definition validates its value before snapshot publication.

71 values: snapshot.values as SessionProjectionValues,

72 }

73 }

74 return blocks

75 }

76

77 private broadcast(frame: SessionControlFrame): void {

78 for (const stream of this.streams) stream.push(frame)

79 }

80}

81

82class ControlQueue {

83 private readonly buffer = new Deque<SessionControlFrame>()

84 private wake: (() => void) | undefined

85 private done = false

86

87 push(frame: SessionControlFrame): void {

88 if (this.done) return

89 this.buffer.pushBack(frame)

90 const wake = this.wake

91 this.wake = undefined

92 wake?.()

93 }

94

95 end(): void {

96 if (this.done) return

97 this.done = true

98 const wake = this.wake

99 this.wake = undefined

100 wake?.()

101 }

102

103 async *iterate(signal: AbortSignal): AsyncIterable<SessionControlFrame> {

104 const onAbort = (): void => { this.end() }

105 signal.addEventListener('abort', onAbort, { once: true })

106 try {

107 while (!this.done && !signal.aborted) {

108 const frame = this.buffer.popFront()

109 if (frame !== undefined) {

110 yield frame

111 continue

112 }

113 await new Promise<void>((resolve) => { this.wake = resolve })

114 }

115 while (this.buffer.size > 0 && !signal.aborted) yield this.buffer.popFront() as SessionControlFrame

116 } finally {

117 signal.removeEventListener('abort', onAbort)

118 this.end()

119 }

120 }

121}