Andyccr · Andyccr · Sep 17, 2026 · Sep 17, 2026
diff --git a/404.html b/404.html
@@ -19,8 +19,8 @@
     <link rel="canonical" href="https://andyccr.github.io/ZenChat/" />
     <link rel="icon" href="./favicon.svg" type="image/svg+xml" />
     <title>禅聊 ZenChat</title>
-    <script type="module" crossorigin src="/ZenChat/assets/index-Ckc1AzqL.js"></script>
-    <link rel="stylesheet" crossorigin href="/ZenChat/assets/index-Bou1xdtq.css">
+    <script type="module" crossorigin src="/ZenChat/assets/index-DfhOSYdI.js"></script>
+    <link rel="stylesheet" crossorigin href="/ZenChat/assets/index-9O3FLWNJ.css">
   </head>
   <body>
     <div id="app"></div>

diff --git a/README.md b/README.md
@@ -17,6 +17,8 @@ flowchart LR
     RM[RoomManager]
     CS[ChatSession]
     SM[SessionMachine]
+    HB[Heartbeat]
+    PR[PayloadRouter]
     OB[Outbound]
     P[Presence]
     L[Transcript]
@@ -34,10 +36,12 @@ flowchart LR
   end
 
   UI --> RM --> CS
-  CS --> SM[SessionMachine]
-  CS --> OB[Outbound]
-  CS --> P[Presence]
-  CS --> L[Transcript]
+  CS --> SM
+  CS --> HB
+  CS --> PR
+  CS --> OB
+  CS --> P
+  CS --> L
   CS --> TR
 
   TR -->|"SDP / ICE (signalling only)"| WT
@@ -48,12 +52,14 @@ flowchart LR
 
 | Layer / 层 | Role / 职责 |
 |---|---|
-| UI Shell | Lobby, tabs, theme. Chat pane is a separate view; shell does not remount on switch. |
-| RoomManager | Room lifecycle, log cache, skip reconnect if the same room is already joined. |
-| ChatSession | Thin orchestrator: transport in, machine + outbound + presence + transcript out. |
-| SessionMachine | Pure join/wait/live/error transitions. |
-| Outbound | Delivery timers. Peers that advertise `ack` in hello get a receipt. |
-| Presence / Transcript | Members + typing TTL; capped message log and dedupe ids. |
+| UI Shell | Lobby, tabs, theme. Chat pane is a separate view; shell does not remount on switch. Failed self lines are tappable to resend. |
+| RoomManager | Room lifecycle, durable log cache, skip reconnect if the same room is already joined. UI never reaches into `ChatSession`. |
+| ChatSession | Thin orchestrator: transport in, machine + heartbeat + router + outbound + presence + transcript out. |
+| SessionMachine | Pure join/wait/live/error transitions. Status copy is derived from the machine. |
+| Heartbeat | Hello interval, relay/RTT poll, visibility pause, stale presence prune. |
+| PayloadRouter | Decode v1 hello/typing/ack/chat; session only applies effects. |
+| Outbound | Delivery timers plus the original payload so a late ack or tap-to-resend can settle. Peers that advertise `ack` in hello get a receipt. |
+| Presence / Transcript | Members + typing TTL + last-seen prune; capped message log, dedupe ids, durable hydrate (drop pending, keep failed). |
 | Transport factory | Default Trystero torrent/nostr. Tests inject a fake. A `Libp2pTransport` can plug in here. |
 | DataChannel | Encrypted chat after ICE succeeds. Trackers never see plaintext. |
 

diff --git a/assets/index-Bou1xdtq.css → assets/index-9O3FLWNJ.css b/assets/index-Bou1xdtq.css → assets/index-9O3FLWNJ.css
diff --git a/assets/index-Ckc1AzqL.js b/assets/index-Ckc1AzqL.js
diff --git a/assets/index-DfhOSYdI.js b/assets/index-DfhOSYdI.js
diff --git a/index.html b/index.html
@@ -19,8 +19,8 @@
     <link rel="canonical" href="https://andyccr.github.io/ZenChat/" />
     <link rel="icon" href="./favicon.svg" type="image/svg+xml" />
     <title>禅聊 ZenChat</title>
-    <script type="module" crossorigin src="/ZenChat/assets/index-Ckc1AzqL.js"></script>
-    <link rel="stylesheet" crossorigin href="/ZenChat/assets/index-Bou1xdtq.css">
+    <script type="module" crossorigin src="/ZenChat/assets/index-DfhOSYdI.js"></script>
+    <link rel="stylesheet" crossorigin href="/ZenChat/assets/index-9O3FLWNJ.css">
   </head>
   <body>
     <div id="app"></div>

diff --git a/src/config/app.ts b/src/config/app.ts
@@ -12,6 +12,7 @@ export const TYPING_TTL_MS = 2500
 export const TYPING_THROTTLE_MS = 1800
 export const HELLO_INTERVAL_MS = 25_000
 export const RELAY_POLL_MS = 5000
+export const PRESENCE_STALE_MS = HELLO_INTERVAL_MS * 3
 export const ACK_TIMEOUT_MS = 8000
 export const SOURCE_URL = 'https://github.com/Andyccr/ZenChat'
 export const PAGES_URL = 'https://andyccr.github.io/ZenChat/'
diff --git a/src/core/cache.test.ts b/src/core/cache.test.ts
@@ -26,4 +26,16 @@ describe('room log cache', () => {
     saveRoomLog(spec, lines)
     expect(loadRoomLog(spec)).toEqual(lines)
   })
+
+  it('strips in-flight pending markers but keeps failed delivery', () => {
+    const spec = { name: 'lobby', password: '', strategy: 'torrent' as const }
+    saveRoomLog(spec, [
+      { kind: 'chat', id: 'p1', fromId: 'me', nick: '晚风', text: 'hi', ts: 1, self: true, delivery: 'pending' },
+      { kind: 'chat', id: 'f1', fromId: 'me', nick: '晚风', text: 'bye', ts: 2, self: true, delivery: 'failed' },
+    ])
+    expect(loadRoomLog(spec)).toEqual([
+      { kind: 'chat', id: 'p1', fromId: 'me', nick: '晚风', text: 'hi', ts: 1, self: true },
+      { kind: 'chat', id: 'f1', fromId: 'me', nick: '晚风', text: 'bye', ts: 2, self: true, delivery: 'failed' },
+    ])
+  })
 })
diff --git a/src/core/cache.ts b/src/core/cache.ts
@@ -20,14 +20,31 @@ export function loadRoomLog(spec: RoomSpec): ChatLine[] {
   }
 }
 
+export function durableLines(lines: ChatLine[]): ChatLine[] {
+  return trimLines(lines.map(dropPendingDelivery))
+}
+
 export function saveRoomLog(spec: RoomSpec, lines: ChatLine[]): void {
   try {
-    sessionStorage.setItem(cacheKey(spec), JSON.stringify(lines.slice(-MAX_LOG_LINES)))
+    sessionStorage.setItem(cacheKey(spec), JSON.stringify(durableLines(lines)))
   } catch {
     // Quota errors are non-fatal; the live session still works.
   }
 }
 
+function dropPendingDelivery(line: ChatLine): ChatLine {
+  if (line.kind !== 'chat' || line.delivery !== 'pending') return line
+  return {
+    kind: 'chat',
+    id: line.id,
+    fromId: line.fromId,
+    nick: line.nick,
+    text: line.text,
+    ts: line.ts,
+    self: line.self,
+  }
+}
+
 export function trimLines(lines: ChatLine[]): ChatLine[] {
   return lines.length > MAX_LOG_LINES ? lines.slice(-MAX_LOG_LINES) : lines
 }

diff --git a/src/core/heartbeat.test.ts b/src/core/heartbeat.test.ts
@@ -0,0 +1,36 @@
+import { describe, expect, it } from 'vitest'
+import { Heartbeat } from './heartbeat'
+import { createMemoryRuntime } from './runtime'
+
+describe('Heartbeat', () => {
+  it('polls and hellos on interval, pauses while hidden, and resumes with a burst', () => {
+    const clock = createMemoryRuntime(0)
+    const hellos: number[] = []
+    const polls: number[] = []
+    const beat = new Heartbeat(clock.runtime, 25, 10, {
+      onHello: () => hellos.push(clock.runtime.now()),
+      onPoll: () => polls.push(clock.runtime.now()),
+    })
+
+    beat.start()
+    clock.advance(25)
+    expect(hellos).toEqual([25])
+    expect(polls).toEqual([10, 20])
+
+    clock.setHidden(true)
+    clock.advance(40)
+    expect(hellos).toEqual([25])
+    expect(polls).toEqual([10, 20])
+
+    clock.setHidden(false)
+    expect(hellos.at(-1)).toBe(65)
+    expect(polls.at(-1)).toBe(65)
+    clock.advance(10)
+    expect(polls.at(-1)).toBe(75)
+
+    beat.stop()
+    clock.advance(50)
+    expect(hellos).toHaveLength(2)
+    expect(polls.filter((at) => at > 75)).toEqual([])
+  })
+})
diff --git a/src/core/heartbeat.ts b/src/core/heartbeat.ts
@@ -0,0 +1,58 @@
+import type { Runtime } from './runtime'
+
+export type HeartbeatHandlers = {
+  onHello: () => void
+  onPoll: () => void
+}
+
+export class Heartbeat {
+  private helloTimer: number | null = null
+  private pollTimer: number | null = null
+  private unbindVisibility: (() => void) | null = null
+
+  constructor(
+    private runtime: Pick<Runtime, 'hidden' | 'setInterval' | 'clearInterval' | 'onVisibilityChange'>,
+    private helloMs: number,
+    private pollMs: number,
+    private handlers: HeartbeatHandlers,
+  ) {}
+
+  start(): void {
+    this.stop()
+    this.unbindVisibility = this.runtime.onVisibilityChange(this.onVisibility)
+    this.startTimers()
+  }
+
+  stop(): void {
+    this.unbindVisibility?.()
+    this.unbindVisibility = null
+    this.stopTimers()
+  }
+
+  private onVisibility = (): void => {
+    if (this.runtime.hidden()) {
+      this.stopTimers()
+      return
+    }
+    this.startTimers()
+    this.handlers.onHello()
+    this.handlers.onPoll()
+  }
+
+  private startTimers(): void {
+    this.stopTimers()
+    this.helloTimer = this.runtime.setInterval(() => this.handlers.onHello(), this.helloMs)
+    this.pollTimer = this.runtime.setInterval(() => this.handlers.onPoll(), this.pollMs)
+  }
+
+  private stopTimers(): void {
+    if (this.helloTimer !== null) {
+      this.runtime.clearInterval(this.helloTimer)
+      this.helloTimer = null
+    }
+    if (this.pollTimer !== null) {
+      this.runtime.clearInterval(this.pollTimer)
+      this.pollTimer = null
+    }
+  }
+}
diff --git a/src/core/outbound.test.ts b/src/core/outbound.test.ts
@@ -3,25 +3,28 @@ import { Outbound } from './outbound'
 import { createMemoryRuntime } from './runtime'
 
 describe('Outbound', () => {
-  it('expires pending ids and ignores a late ack', () => {
+  it('expires pending ids but keeps the payload for a late ack or resend', () => {
     const clock = createMemoryRuntime(0)
     const expired: string[] = []
-    const outbound = new Outbound(clock.runtime, 100, (id) => expired.push(id))
-    outbound.expect('msg-1')
+    const outbound = new Outbound<{ text: string }>(clock.runtime, 100, (id) => expired.push(id))
+    outbound.expect('msg-1', { text: 'hi' })
     clock.advance(99)
     expect(expired).toEqual([])
     clock.advance(1)
     expect(expired).toEqual(['msg-1'])
-    expect(outbound.ack('msg-1')).toBe(false)
+    expect(outbound.payload('msg-1')).toEqual({ text: 'hi' })
+    expect(outbound.ack('msg-1')).toBe(true)
+    expect(outbound.payload('msg-1')).toBeUndefined()
   })
 
   it('clears a timer when the ack arrives first', () => {
     const clock = createMemoryRuntime(0)
     const expired: string[] = []
     const outbound = new Outbound(clock.runtime, 100, (id) => expired.push(id))
-    outbound.expect('msg-2')
+    outbound.expect('msg-2', { text: 'yo' })
     expect(outbound.ack('msg-2')).toBe(true)
     clock.advance(100)
     expect(expired).toEqual([])
+    expect(outbound.payload('msg-2')).toBeUndefined()
   })
 })
diff --git a/src/core/outbound.ts b/src/core/outbound.ts
@@ -1,16 +1,18 @@
 import type { Runtime } from './runtime'
 
-export class Outbound {
+export class Outbound<T = unknown> {
   private timers = new Map<string, number>()
+  private payloads = new Map<string, T>()
 
   constructor(
     private runtime: Pick<Runtime, 'setTimeout' | 'clearTimeout'>,
     private timeoutMs: number,
     private onExpire: (id: string) => void,
   ) {}
 
-  expect(id: string): void {
-    this.cancel(id)
+  expect(id: string, payload?: T): void {
+    this.cancelTimer(id)
+    if (payload !== undefined) this.payloads.set(id, payload)
     this.timers.set(
       id,
       this.runtime.setTimeout(() => {
@@ -21,18 +23,27 @@ export class Outbound {
   }
 
   ack(id: string): boolean {
-    if (!this.timers.has(id)) return false
+    if (!this.timers.has(id) && !this.payloads.has(id)) return false
     this.cancel(id)
     return true
   }
 
+  payload(id: string): T | undefined {
+    return this.payloads.get(id)
+  }
+
   cancel(id: string): void {
-    const timer = this.timers.get(id)
-    if (timer !== undefined) this.runtime.clearTimeout(timer)
-    this.timers.delete(id)
+    this.cancelTimer(id)
+    this.payloads.delete(id)
   }
 
   clear(): void {
-    for (const id of [...this.timers.keys()]) this.cancel(id)
+    for (const id of [...this.timers.keys(), ...this.payloads.keys()]) this.cancel(id)
+  }
+
+  private cancelTimer(id: string): void {
+    const timer = this.timers.get(id)
+    if (timer !== undefined) this.runtime.clearTimeout(timer)
+    this.timers.delete(id)
   }
 }
diff --git a/src/core/payload-router.test.ts b/src/core/payload-router.test.ts
@@ -0,0 +1,24 @@
+import { describe, expect, it } from 'vitest'
+import { decodeIncoming } from './payload-router'
+import { createAckPayload, createChatPayload, createHelloPayload, createTypingPayload } from './protocol'
+
+describe('decodeIncoming', () => {
+  it('drops invalid payloads and marks duplicate chats', () => {
+    expect(decodeIncoming({ v: 1, type: 'leave', nick: '晚风' }, () => false)).toBeNull()
+    expect(decodeIncoming(createHelloPayload('晚风'), () => false)).toEqual({
+      type: 'hello',
+      nick: '晚风',
+      features: ['ack'],
+    })
+    expect(decodeIncoming(createTypingPayload('听雨'), () => false)).toEqual({ type: 'typing', nick: '听雨' })
+    expect(decodeIncoming(createAckPayload('青石', 'aabbccdd12345678'), () => false)).toEqual({
+      type: 'ack',
+      nick: '青石',
+      id: 'aabbccdd12345678',
+    })
+
+    const chat = createChatPayload('青石', '在吗', 'aabbccdd12345678', 1)
+    expect(decodeIncoming(chat, () => false)).toMatchObject({ type: 'chat', duplicate: false, text: '在吗' })
+    expect(decodeIncoming(chat, (id) => id === chat.id)).toMatchObject({ type: 'chat', duplicate: true })
+  })
+})
diff --git a/src/core/payload-router.ts b/src/core/payload-router.ts
@@ -0,0 +1,23 @@
+import { parsePayload } from './protocol'
+
+export type Incoming =
+  | { type: 'hello'; nick: string; features: string[] }
+  | { type: 'typing'; nick: string }
+  | { type: 'ack'; nick: string; id: string }
+  | { type: 'chat'; nick: string; id: string; text: string; ts: number; duplicate: boolean }
+
+export function decodeIncoming(raw: unknown, seen: (id: string) => boolean): Incoming | null {
+  const payload = parsePayload(raw)
+  if (!payload) return null
+  if (payload.type === 'hello') return { type: 'hello', nick: payload.nick, features: payload.features }
+  if (payload.type === 'typing') return { type: 'typing', nick: payload.nick }
+  if (payload.type === 'ack') return { type: 'ack', nick: payload.nick, id: payload.id }
+  return {
+    type: 'chat',
+    nick: payload.nick,
+    id: payload.id,
+    text: payload.text,
+    ts: payload.ts,
+    duplicate: seen(payload.id),
+  }
+}
diff --git a/src/core/presence.test.ts b/src/core/presence.test.ts
@@ -26,4 +26,15 @@ describe('Presence', () => {
     expect(presence.remove('p1')?.nick).toBe('晚风')
     expect(presence.list()).toEqual([])
   })
+
+  it('prunes members whose lastSeenAt is older than the stale window', () => {
+    const clock = createMemoryRuntime(1_000)
+    const presence = new Presence(clock.runtime)
+    presence.upsert('fresh', '晚风')
+    clock.advance(80)
+    presence.upsert('stale', '青石')
+    clock.advance(30)
+    expect(presence.prune(100).map((member) => member.id)).toEqual(['fresh'])
+    expect(presence.list().map((member) => member.id)).toEqual(['stale'])
+  })
 })
diff --git a/src/core/presence.ts b/src/core/presence.ts
@@ -68,6 +68,13 @@ export class Presence {
     return [...this.members.values()].sort((a, b) => a.joinedAt - b.joinedAt)
   }
 
+  prune(maxAgeMs: number): Member[] {
+    const cutoff = this.runtime.now() - maxAgeMs
+    const gone = this.list().filter((member) => member.lastSeenAt < cutoff)
+    for (const member of gone) this.remove(member.id)
+    return gone
+  }
+
   clear(): void {
     for (const id of this.typingTimers.keys()) this.clearTypingTimer(id)
     this.members.clear()