feat(agent): unify send(target × wakeup), coalesce context/message into user/message

Replace send/steer/inject with one Agent.send primitive over the
(target × wakeup) matrix; followup/steer/inject become fixed-preset
alias methods on the now-abstract Agent class. Coalesce context/message
into user/message (injected context is a non-user source). Replace
agent/queued with agent/inbox/enqueue/dequeue/discard, add cancel
keepInbox, and add a FIFO-conservation invariant.

packages/ui/acp/src/index.ts

@@ -1333,8 +1333,8 @@ function validateMcpServers(params: { mcpServers?: unknown[] }): void {
  * generic fallback (title = tool name, raw args as input) when no registry is
  * available (e.g. pure translator tests).
  *
- * Other event types (turn/step boundaries, context/message, …) produce
- * no client update.
+ * Other event types (turn/step boundaries, injected-context user messages, …)
+ * produce no client update.
  * @param sessionId - the ACP session id stamped on every emitted notification.
  * @param event - the harness session event to translate.
  * @param notify - sink for each produced `session/update` notification; called
@@ -1374,6 +1374,9 @@ export function streamSessionEventUpdate(
     }
     case 'user/message': {
       if (!includeUserMessages) return
+      // Only a direct human prompt replays as a user message; injected context
+      // (plugin/goal source) is not the user's turn and produces no update.
+      if (event.data.source.kind !== 'user') return
       // Replay the user's prompt so a loaded session shows both sides of each
       // turn. Live prompt turns suppress this path to avoid duplicating what
       // the client just sent.
@@ -1420,7 +1423,7 @@ export function streamSessionEventUpdate(
       notify({ sessionId, update: { sessionUpdate: 'agent_message_chunk', content: { type: 'text', text } } })
       return
     }
-    // non-error turn/step boundaries, context/message, steering,
+    // non-error turn/step boundaries, injected-context user messages, steering,
     // assistant/message — no direct ACP client update.
     default:
       return

packages/ui/acp/tests/bridge.spec.ts

@@ -383,7 +383,7 @@ describe('acp bridge', () => {
         },
       }],
     })
-    expect(target.events.some(event => event.type === 'context/message')).toBe(false)
+    expect(target.events.some(event => event.type === 'user/message' && event.data.source.kind !== 'user')).toBe(false)
     const request = JSON.stringify(harness.adapter.requests[0]?.messages)
     expect(request).toContain('untrusted, read-only snapshot')
     expect(request).toContain('source background')

packages/ui/acp/tests/turns.spec.ts

@@ -285,10 +285,10 @@ describe('acp bridge — turn outcomes', () => {
     const sessionId = await newSession(harness)
     const agent = harness.ctx.agents.get(SessionId(sessionId))!
     // On the queued prompt, synchronously inject a one-shot context turn (idle
-    // inject writes turn/start{injection} → context/message → turn/end). Fire
+    // inject writes turn/start{injection} → user/message → turn/end). Fire
     // once so it lands between install and the prompt turn.
     let injected = false
-    harness.ctx.on('agent/queued', (subject) => {
+    harness.ctx.on('agent/inbox/enqueue', (subject) => {
       if (subject === agent && !injected) {
         injected = true
         agent.inject([{ type: 'text', text: 'ctx note' }], { source: { kind: 'plugin', plugin: 'test' } })

packages/ui/jsonrpc/tests/server.spec.ts

@@ -241,7 +241,7 @@ describe('HarnessSdkServer', () => {
           turn: 2,
           trigger: { kind: 'injection', source: { kind: 'plugin', plugin: 'late-metadata' } },
         })
-        session.append('context/message', {
+        session.append('user/message', {
           content: [{ type: 'text', text: 'late metadata' }],
           source: { kind: 'plugin', plugin: 'late-metadata' },
         }, { surfaceOp: 'append' })

packages/ui/tui/src/index.ts

@@ -1487,12 +1487,12 @@ export function createTuiChat(
   let toolsExpanded = false
   let streaming: StreamingAssistantComponent | undefined
   let runningStatus: RunningStatus | undefined
-  // Steering messages queued during the running turn (`agent/queued`) that the
-  // loop has not yet drained, shown as a badge on the status line. Each entry is
-  // the queued message's serialized source: a drain (`steering/message`) removes
-  // one MATCHING entry, so loop-authored steering — continuation reasons enter
-  // the inbox without an `agent/queued` event — cannot consume a pending user
-  // message's slot. Cleared on leaving `running`, which also absorbs a
+  // Steering messages queued during the running turn (`agent/inbox/enqueue`)
+  // that the loop has not yet drained, shown as a badge on the status line. Each
+  // entry is the queued message's serialized source: a drain (`steering/message`)
+  // removes one MATCHING entry, so loop-authored steering — continuation reasons
+  // enter the inbox without an `agent/inbox/enqueue` event — cannot consume a
+  // pending user message's slot. Cleared on leaving `running`, which also absorbs a
   // cancellation that discards the queue without logging drains; the status
   // line exists only while running, so idle carries no badge to keep current.
   const pendingSteering: string[] = []
@@ -1795,6 +1795,29 @@ export function createTuiChat(
   const renderEvent = (event: SessionEvent, options: { addHistory: boolean; renderChunks: boolean }): void => {
     switch (event.type) {
       case 'user/message': {
+        // Injected context (plugin/goal source) renders as a dim context card,
+        // not a human bubble; only a direct human prompt is a user message. The
+        // boolean avoids narrowing `source`, so the label keeps its full union.
+        const source = event.data.source
+        if (source.kind !== 'user') {
+          const references = sessionReferenceCard(event.data.meta)
+          if (references !== undefined) {
+            chat.addChild(new Spacer(1))
+            chat.addChild(new Text(palette.dim(`Referenced sessions · ${references.map(displayText).join(', ')}`), 1, 0))
+            break
+          }
+          const text = displayText(contentText(event.data.content).trim())
+          if (text) {
+            // The tui type view lacks plugin-augmented source kinds (e.g. goal),
+            // so read the display label without narrowing on `kind`.
+            const labelled = source as { kind: string; plugin?: string }
+            const label = labelled.plugin ?? labelled.kind
+            chat.addChild(new Spacer(1))
+            chat.addChild(new Text(palette.dim(`Context · ${displayText(label)}`), 1, 0))
+            chat.addChild(new Text(palette.muted(text), 1, 0))
+          }
+          break
+        }
         const text = displayText(contentText(displayPromptContent(event.data)).trim())
         if (text) {
           chat.addChild(new Spacer(1))
@@ -1819,22 +1842,6 @@ export function createTuiChat(
         }
         break
       }
-      case 'context/message': {
-        const references = sessionReferenceCard(event.data.meta)
-        if (references !== undefined) {
-          chat.addChild(new Spacer(1))
-          chat.addChild(new Text(palette.dim(`Referenced sessions · ${references.map(displayText).join(', ')}`), 1, 0))
-          break
-        }
-        const text = displayText(contentText(event.data.content).trim())
-        if (text) {
-          const source = event.data.source.kind === 'plugin' ? event.data.source.plugin : event.data.source.kind
-          chat.addChild(new Spacer(1))
-          chat.addChild(new Text(palette.dim(`Context · ${displayText(source)}`), 1, 0))
-          chat.addChild(new Text(palette.muted(text), 1, 0))
-        }
-        break
-      }
       case 'prompt/blocked':
         appendNotice(`Prompt blocked: ${event.data.reason}`, 'warning')
         break
@@ -1919,7 +1926,6 @@ export function createTuiChat(
       const isSurface = event.type === 'user/message'
         || event.type === 'assistant/message'
         || event.type === 'tool/result'
-        || event.type === 'context/message'
         || event.type === 'steering/message'
       if (isSurface && !active.has(event.seq)) continue
       if (event.type === 'tool/call' && !activeCalls.has(event.data.callId)) continue
@@ -2554,7 +2560,7 @@ export function createTuiChat(
       // A queued steering message reached the model as it drained; drop its
       // entry from the badge. Matching by source keeps loop-authored steering
       // (e.g. continuation reasons), which logs here without a matching
-      // `agent/queued` increment, from consuming a pending user slot.
+      // `agent/inbox/enqueue` increment, from consuming a pending user slot.
       const drained = pendingSteering.indexOf(JSON.stringify(event.data.source))
       if (drained >= 0) {
         pendingSteering.splice(drained, 1)
@@ -2568,7 +2574,7 @@ export function createTuiChat(
     renderEvent(event, { addHistory: false, renderChunks: true })
     requestRender()
   })
-  const disposeQueued = ctx.on('agent/queued', (subject, _content, info) => {
+  const disposeQueued = ctx.on('agent/inbox/enqueue', (subject, info) => {
     if (subject !== agent || !info.steering) return
     pendingSteering.push(JSON.stringify(info.source))
     refreshStatus()

packages/ui/tui/tests/harness.ts

@@ -153,6 +153,10 @@ export async function createTuiTestHarness<TerminalType extends Terminal, Exit e
       sent.push(content)
       sentOptions.push(options)
     },
+    followup(content, options) {
+      sent.push(content)
+      sentOptions.push(options)
+    },
     steer(content, options) {
       steered.push(content)
       steeredOptions.push(options)

packages/ui/tui/tests/session-reference.snapshot.ts

@@ -128,7 +128,7 @@ describe('TUI session-reference snapshot', () => {
       type: 'text',
       text: '\n\n## My request:\n',
     })
-    expect(target.session.events.some(event => event.type === 'context/message')).toBe(false)
+    expect(target.session.events.some(event => event.type === 'user/message' && event.data.source.kind !== 'user')).toBe(false)
 
     const snapshot = await terminal.snapshot({ includeScrollback: true })
     if (REFRESHING) {

packages/ui/tui/tests/tui.snapshot.ts

@@ -451,7 +451,7 @@ describe('TUI terminal-state snapshots', () => {
         session.append('todo/write', {
           todos: [{ content: `Unsafe todo ${CONTROL_PROBE}`, status: 'in_progress' }],
         })
-        session.append('context/message', {
+        session.append('user/message', {
           content: [{ type: 'text', text: `Unsafe context ${CONTROL_PROBE}` }],
           source: { kind: 'plugin', plugin: `unsafe-${CONTROL_PROBE}` },
         }, { surfaceOp: 'append' })
@@ -567,7 +567,7 @@ describe('TUI terminal-state snapshots', () => {
     await checkpoint('surface-before-compaction', harness.terminal, { includeScrollback: true })
 
     await renderAfter(harness, () => {
-      harness.session.append('context/message', {
+      harness.session.append('user/message', {
         content: [{ type: 'text', text: 'Compacted summary: the prior command completed and its details were retired from the active surface.' }],
         source: { kind: 'plugin', plugin: 'compact' },
       }, {

packages/ui/tui/tests/tui.spec.ts

@@ -374,8 +374,8 @@ describe('pi-tui chat lifecycle and transcript', () => {
     result.session.append('user/message', { content: [{ type: 'text', text: '   ' }], source: { kind: 'user' } }, { surfaceOp: 'append' })
     result.session.append('steering/message', { turn: 2, content: [{ type: 'text', text: 'steering note' }], source: { kind: 'user' } }, { surfaceOp: 'append' })
     result.session.append('steering/message', { turn: 2, content: [{ type: 'text', text: '' }], source: { kind: 'user' } }, { surfaceOp: 'append' })
-    result.session.append('context/message', { content: [{ type: 'text', text: 'user context' }], source: { kind: 'user' } }, { surfaceOp: 'append' })
-    result.session.append('context/message', { content: [{ type: 'text', text: '' }], source: { kind: 'user' } }, { surfaceOp: 'append' })
+    result.session.append('user/message', { content: [{ type: 'text', text: 'user context' }], source: { kind: 'plugin', plugin: 'ctx' } }, { surfaceOp: 'append' })
+    result.session.append('user/message', { content: [{ type: 'text', text: '' }], source: { kind: 'plugin', plugin: 'ctx' } }, { surfaceOp: 'append' })
     result.session.append('prompt/blocked', { content: [{ type: 'text', text: 'blocked' }], source: { kind: 'user' }, reason: 'test policy' })
     appendAssistant(result.session, [])
     result.session.append('step/end', { turn: 1, step: 1 })
@@ -552,16 +552,16 @@ describe('pi-tui chat lifecycle and transcript', () => {
     expect(result.terminal.output).not.toContain('queued')
 
     const queueSteering = (text: string): void => {
-      result.ctx.emit('agent/queued', result.agent, [{ type: 'text', text }], { source: { kind: 'user' }, contexts: [], steering: true })
+      result.ctx.emit('agent/inbox/enqueue', result.agent, { content: [{ type: 'text', text }], source: { kind: 'user' }, contexts: [], steering: true, wakeup: true })
     }
     const drainSteering = (text: string): void => {
       result.session.append('steering/message', { turn: 1, content: [{ type: 'text', text }], source: { kind: 'user' } }, { surfaceOp: 'append' })
     }
 
     // A steering queue for a different agent never touches this status line.
-    const other = { ...result.agent, id: SessionId('other') } as Agent
+    const other = { ...result.agent, id: SessionId('other') } as unknown as Agent
     result.terminal.output = ''
-    result.ctx.emit('agent/queued', other, [{ type: 'text', text: 'elsewhere' }], { source: { kind: 'user' }, contexts: [], steering: true })
+    result.ctx.emit('agent/inbox/enqueue', other, { content: [{ type: 'text', text: 'elsewhere' }], source: { kind: 'user' }, contexts: [], steering: true, wakeup: true })
     await tick()
     expect(result.terminal.output).not.toContain('queued')
 
@@ -574,7 +574,7 @@ describe('pi-tui chat lifecycle and transcript', () => {
 
     // A non-steering queue (an idle-style send) leaves the badge untouched.
     result.terminal.output = ''
-    result.ctx.emit('agent/queued', result.agent, [{ type: 'text', text: 'sent' }], { source: { kind: 'user' }, contexts: [], steering: false })
+    result.ctx.emit('agent/inbox/enqueue', result.agent, { content: [{ type: 'text', text: 'sent' }], source: { kind: 'user' }, contexts: [], steering: false, wakeup: true })
     drainSteering('first')
     await tick()
     expect(result.terminal.output).toContain('1 queued')
@@ -594,7 +594,7 @@ describe('pi-tui chat lifecycle and transcript', () => {
     await tick()
     expect(result.terminal.output).toContain('1 queued')
 
-    // A loop-authored steering event (plugin source, no matching agent/queued)
+    // A loop-authored steering event (plugin source, no matching agent/inbox/enqueue)
     // cannot consume a pending user slot, even when it drains first.
     result.terminal.output = ''
     result.session.append('steering/message', {
@@ -627,7 +627,7 @@ describe('pi-tui chat lifecycle and transcript', () => {
     const idle = await setup()
     // A steering queue arriving while idle has no status line to badge, so the
     // refresh is a no-op beyond requesting a render.
-    idle.ctx.emit('agent/queued', idle.agent, [{ type: 'text', text: 'early' }], { source: { kind: 'user' }, contexts: [], steering: true })
+    idle.ctx.emit('agent/inbox/enqueue', idle.agent, { content: [{ type: 'text', text: 'early' }], source: { kind: 'user' }, contexts: [], steering: true, wakeup: true })
     idle.session.append('tool/call', { turn: 1, step: 0, callId: 'pre' as never, name: 'bash', arguments: '{}' })
     await tick()
     expect(idle.terminal.output).not.toContain('Executing tools')
@@ -1221,7 +1221,7 @@ describe('pi-tui chat lifecycle and transcript', () => {
     expect(result.terminal.output).toContain('Referenced sessions · Steering source (steering-source)')
     expect(result.terminal.output).not.toContain('hidden non-reference prefix')
 
-    result.session.append('context/message', {
+    result.session.append('user/message', {
       content: [{ type: 'text', text: 'secret full snapshot payload' }],
       source: { kind: 'plugin', plugin: 'session-reference' },
       meta: {
@@ -1240,13 +1240,13 @@ describe('pi-tui chat lifecycle and transcript', () => {
       [{ kind: 'session-reference', references: [{}] }, 'invalid-fields'],
     ]
     for (const [meta, text] of invalidCards) {
-      result.session.append('context/message', {
+      result.session.append('user/message', {
         content: [{ type: 'text', text }],
         source: { kind: 'plugin', plugin: 'session-reference' },
         meta,
       }, { surfaceOp: 'append' })
     }
-    result.session.append('context/message', {
+    result.session.append('user/message', {
       content: [{ type: 'text', text: 'same-label snapshot' }],
       source: { kind: 'plugin', plugin: 'session-reference' },
       meta: { kind: 'session-reference', references: [{ sessionId: 'same', label: 'same' }] },
@@ -1658,7 +1658,7 @@ describe('pi-tui chat lifecycle and transcript', () => {
 
     const events = await setup()
     const unrelatedSession = events.ctx.sessions.create(SessionId('unrelated-session'))
-    const unrelatedAgent = { ...events.agent, id: unrelatedSession.id, session: unrelatedSession }
+    const unrelatedAgent = { ...events.agent, id: unrelatedSession.id, session: unrelatedSession } as unknown as Agent
     unrelatedSession.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
     unrelatedSession.append('todo/write', { todos: [{ content: 'hidden', status: 'pending' }] })
     agentEvents(events.ctx, unrelatedAgent).emit('agent/status', 'running')
@@ -2021,7 +2021,7 @@ describe('tool cards and surface replay', () => {
       turn: 1, step: 1, callId: 'old-call' as never, content: [{ type: 'text', text: 'old output' }], isError: false,
     }, { surfaceOp: 'append' })
     const start = result.session.surface.nodes[0] as number
-    result.session.append('context/message', {
+    result.session.append('user/message', {
       content: [{ type: 'text', text: 'summary replacement' }],
       source: { kind: 'plugin', plugin: 'compact' },
     }, {
@@ -2207,7 +2207,7 @@ describe('terminal mounting', () => {
     const session = ctx.sessions.create(SessionId('main'))
     ctx.agents.register({
       id: session.id, options: {}, session, status: 'idle', ctx,
-      send() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
+      send() {}, followup() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
     })
     const terminal = new FakeTerminal()
     mountTui(ctx, { color: false }, { terminal, exit: vi.fn() })
@@ -2231,7 +2231,7 @@ describe('terminal mounting', () => {
     const session = ctx.sessions.create(SessionId('main'))
     ctx.agents.register({
       id: session.id, options: {}, session, status: 'idle', ctx,
-      send() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
+      send() {}, followup() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
     })
     const terminal = new FakeTerminal()
     // Mirror dsh-tui's own inject (minus loader, the absence under test).
@@ -2265,14 +2265,14 @@ describe('terminal mounting', () => {
     const otherSession = ctx.sessions.create(SessionId('other-session'))
     ctx.agents.register({
       id: otherSession.id, options: {}, session: otherSession, status: 'idle', ctx,
-      send() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
+      send() {}, followup() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
     })
     expect(terminal.started).toBe(0)
 
     const session = ctx.sessions.create(SessionId('late-session'))
     const agent = {
       id: session.id, options: {}, session, status: 'idle', ctx,
-      send() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
+      send() {}, followup() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
     } as Agent
     ctx.agents.register(agent)
     await tick()
@@ -2302,7 +2302,7 @@ describe('terminal mounting', () => {
     const session = ctx.sessions.create(SessionId('main-session'))
     ctx.agents.register({
       id: session.id, options: {}, session, status: 'idle', ctx,
-      send() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
+      send() {}, followup() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
     })
     await tick()
     expect(terminal.started).toBe(0)
@@ -2344,7 +2344,7 @@ describe('terminal mounting', () => {
     session.append('step/start', { turn: 1, step: 1 })
     ctx.agents.register({
       id: session.id, options: {}, session, status: 'running', ctx,
-      send() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
+      send() {}, followup() {}, steer() {}, inject() {}, cancel() {}, whenIdle: () => Promise.resolve(),
     })
     const terminal = new FakeTerminal()
     terminal.start = () => { throw new Error('terminal startup failed') }