apps/desktop/src/main/model.ts

@@ -86,11 +86,15 @@ export function registerModelIpc(): void {
     return { configured: true, model }
   })
 
-  ipcMain.handle('model:chat', async (_event, messages: ChatMessage[]) => {
+  ipcMain.handle('model:chat', async (event, messages: ChatMessage[]) => {
     if (!router) return { ok: false as const, reason: 'unconfigured' as const }
     const client = getGiteaClient()
     const model = await resolveLoadedModel(router.small.baseUrl, router.small.model)
     const chat = createChatClient({ ...router.small, model }, fetch)
+    // stream the model's prose to the renderer token-by-token
+    const onToken = (delta: string) => {
+      if (!event.sender.isDestroyed()) event.sender.send('model:chat:token', delta)
+    }
 
     // Proposals the model formulates this turn; the renderer approves them (the
     // write happens through gitea:applyChange, never inside the loop).
@@ -129,10 +133,11 @@ export function registerModelIpc(): void {
 
     try {
       const turn = await runAgentTurn({
-        complete: (m, t) => chat.complete(m, t),
+        complete: (m, t, ot) => chat.complete(m, t, ot),
         messages: [{ role: 'system', content: REGINALD_SYSTEM }, ...messages],
         tools: REGINALD_TOOLS,
         execute,
+        onToken,
       })
       return { ok: true as const, content: turn.content, steps: turn.steps, proposals }
     } catch (e) {

apps/desktop/src/preload/index.ts

@@ -25,6 +25,12 @@ const api = {
     status: () => ipcRenderer.invoke('model:status'),
     /** One agent turn: messages in, Reginald's prose + the tools it consulted out. */
     chat: (messages: unknown) => ipcRenderer.invoke('model:chat', messages),
+    /** Subscribe to streamed prose tokens for the in-flight turn; returns an unsubscribe. */
+    onToken: (cb: (delta: string) => void) => {
+      const listener = (_e: unknown, delta: string) => cb(delta)
+      ipcRenderer.on('model:chat:token', listener)
+      return () => ipcRenderer.removeListener('model:chat:token', listener)
+    },
     /** Decompose a braindump into a proposed issue set (capture_work). */
     capture: (braindump: string) => ipcRenderer.invoke('model:capture', braindump),
   },

apps/desktop/src/renderer/src/components/shell/chat-panel.tsx

@@ -19,7 +19,7 @@ export interface ChatPanelProps {
 }
 
 export function ChatPanel({ onOpenDirectives, offline, onApplyChange }: ChatPanelProps) {
-  const { msgs, thinking, live, model, steps, proposals, send: sendChat, approve, dismiss } = useChat(onApplyChange)
+  const { msgs, thinking, live, model, steps, proposals, streaming, send: sendChat, approve, dismiss } = useChat(onApplyChange)
   // shorten "google/gemma-4-26b-a4b-qat" → "gemma-4-26b" for the header chip
   const modelLabel = model ? (model.split('/').pop() ?? model).replace(/-(qat|instruct|it|gguf)$/i, '') : 'gemma-4'
   const [text, setText] = useState('')
@@ -28,7 +28,7 @@ export function ChatPanel({ onOpenDirectives, offline, onApplyChange }: ChatPane
   useEffect(() => {
     const el = scrollRef.current
     if (el) el.scrollTop = el.scrollHeight
-  }, [msgs, thinking])
+  }, [msgs, thinking, streaming])
 
   const send = () => {
     const t = text.trim()
@@ -98,7 +98,14 @@ export function ChatPanel({ onOpenDirectives, offline, onApplyChange }: ChatPane
             The model is away from its desk. Reads still work; writes will wait their turn.
           </div>
         ) : null}
-        {thinking ? <div style={{ font: 'var(--text-agent)', color: 'var(--ink-3)' }}>considering…</div> : null}
+        {streaming ? (
+          <div style={{ font: 'var(--text-agent)', color: 'var(--ink-1)', lineHeight: 1.55 }}>
+            {streaming}
+            <span style={{ opacity: 0.5 }}>▊</span>
+          </div>
+        ) : thinking ? (
+          <div style={{ font: 'var(--text-agent)', color: 'var(--ink-3)' }}>considering…</div>
+        ) : null}
         {!thinking && steps.length ? (
           <div style={{ font: 'var(--text-caption)', color: 'var(--ink-3)', display: 'flex', alignItems: 'center', gap: 5 }}>
             <Icon name="eye" size={11} /> consulted {Array.from(new Set(steps.map((s) => s.replace('query_project', 'the project').replace('propose_change', 'the labels').replace('record_directive', 'the directive ledger')))).join(', ')}

apps/desktop/src/renderer/src/global.d.ts

@@ -68,6 +68,8 @@ export interface ModelBridge {
   status(): Promise<{ configured: boolean; model: string | null }>
   chat(messages: ChatMessage[]): Promise<ChatResult>
   capture(braindump: string): Promise<CaptureResult>
+  /** Subscribe to streamed prose tokens; returns an unsubscribe fn. */
+  onToken(cb: (delta: string) => void): () => void
 }
 
 /** The result of reading the directive ledger. */

apps/desktop/src/renderer/src/lib/use-chat.ts

@@ -20,6 +20,8 @@ export interface ChatState {
   steps: string[]
   /** Changes Reginald has proposed and is awaiting approval on. */
   proposals: ChangeProposal[]
+  /** The in-flight streamed prose (grows token-by-token) before the turn finalizes. */
+  streaming: string
   send: (text: string) => void
   approve: (p: ChangeProposal) => void
   dismiss: (p: ChangeProposal) => void
@@ -41,6 +43,7 @@ export function useChat(onApplyChange?: (change: IssueChange) => Promise<{ ok: b
   const [model, setModel] = useState<string | null>(null)
   const [steps, setSteps] = useState<string[]>([])
   const [proposals, setProposals] = useState<ChangeProposal[]>([])
+  const [streaming, setStreaming] = useState('')
   const convoRef = useRef(convo)
   convoRef.current = convo
 
@@ -86,10 +89,17 @@ export function useChat(onApplyChange?: (change: IssueChange) => Promise<{ ok: b
         role: m.from === 'user' ? 'user' : 'assistant',
         content: m.text,
       }))
+      setStreaming('')
+      const unsubscribe = window.commitea.model.onToken((delta) => setStreaming((s) => s + delta))
+      const finish = () => {
+        unsubscribe()
+        setThinking(false)
+        setStreaming('')
+      }
       window.commitea.model
         .chat(wire)
         .then((res) => {
-          setThinking(false)
+          finish()
           if (res.ok) {
             setSteps(res.steps.map((s) => s.tool))
             setProposals(res.proposals)
@@ -105,7 +115,7 @@ export function useChat(onApplyChange?: (change: IssueChange) => Promise<{ ok: b
           }
         })
         .catch(() => {
-          setThinking(false)
+          finish()
           setConvo((c) => [...c, { from: 'agent', text: 'I could not reach the model.' }])
         })
     },
@@ -137,5 +147,5 @@ export function useChat(onApplyChange?: (change: IssueChange) => Promise<{ ok: b
     setConvo((c) => [...c, { from: 'agent', text: `Left #${p.change.issue} as it was.` }])
   }, [])
 
-  return { msgs: [...seed, ...convo], thinking, live, model, steps, proposals, send, approve, dismiss }
+  return { msgs: [...seed, ...convo], thinking, live, model, steps, proposals, streaming, send, approve, dismiss }
 }

packages/core/src/agent/agent-loop.ts

@@ -31,18 +31,20 @@ function stringify(result: unknown): string {
 }
 
 export async function runAgentTurn(opts: {
-  complete: (messages: ChatMessage[], tools?: ToolDecl[]) => Promise<CompletionResult>
+  complete: (messages: ChatMessage[], tools?: ToolDecl[], onToken?: (delta: string) => void) => Promise<CompletionResult>
   messages: ChatMessage[]
   tools: ToolDecl[]
   execute: ToolExecutor
   maxSteps?: number
+  /** Streams content deltas as the model produces prose (final-answer streaming). */
+  onToken?: (delta: string) => void
 }): Promise<AgentTurn> {
   const maxSteps = opts.maxSteps ?? DEFAULT_MAX_STEPS
   const convo: ChatMessage[] = [...opts.messages]
   const steps: AgentStep[] = []
 
   for (let step = 0; step < maxSteps; step++) {
-    const { content, toolCalls } = await opts.complete(convo, opts.tools)
+    const { content, toolCalls } = await opts.complete(convo, opts.tools, opts.onToken)
     if (toolCalls.length === 0) {
       convo.push({ role: 'assistant', content })
       return { content, steps, messages: convo }
@@ -63,7 +65,7 @@ export async function runAgentTurn(opts: {
   }
 
   // Out of tool budget — force a final prose answer with tools withheld.
-  const final = await opts.complete(convo, [])
+  const final = await opts.complete(convo, [], opts.onToken)
   convo.push({ role: 'assistant', content: final.content })
   return { content: final.content, steps, messages: convo }
 }

packages/core/src/agent/agent.test.ts

@@ -25,6 +25,48 @@ describe('createChatClient', () => {
     return { fetch, calls }
   }
 
+  function sseStub(chunks: string[]) {
+    const calls: { url: string; body: unknown }[] = []
+    const fetch: FetchLike = (url, init) => {
+      calls.push({ url, body: init?.body ? JSON.parse(init.body) : undefined })
+      const enc = new TextEncoder()
+      const body = new ReadableStream<Uint8Array>({
+        start(c) {
+          for (const ch of chunks) c.enqueue(enc.encode(ch))
+          c.close()
+        },
+      })
+      return Promise.resolve({ ok: true, status: 200, body, json: () => Promise.resolve({}), text: () => Promise.resolve('') })
+    }
+    return { fetch, calls }
+  }
+
+  it('streams content deltas via onToken and returns the assembled result', async () => {
+    const { fetch, calls } = sseStub([
+      'data: {"choices":[{"delta":{"content":"Right "}}]}\n\n',
+      'data: {"choices":[{"delta":{"content":"now: #2."}}]}\n\n',
+      'data: [DONE]\n\n',
+    ])
+    const client = createChatClient({ baseUrl: 'http://x/v1', model: 'm' }, fetch)
+    const tokens: string[] = []
+    const res = await client.complete([{ role: 'user', content: 'now?' }], undefined, (d) => tokens.push(d))
+
+    expect(tokens).toEqual(['Right ', 'now: #2.'])
+    expect(res.content).toBe('Right now: #2.')
+    expect((calls[0].body as { stream?: boolean }).stream).toBe(true)
+  })
+
+  it('assembles a streamed tool call from argument deltas', async () => {
+    const { fetch } = sseStub([
+      'data: {"choices":[{"delta":{"tool_calls":[{"index":0,"id":"c1","function":{"name":"query_project","arguments":"{\\"view\\""}}]}}]}\n\n',
+      'data: {"choices":[{"delta":{"tool_calls":[{"index":0,"function":{"arguments":":\\"focus\\"}"}}]}}]}\n\n',
+      'data: [DONE]\n\n',
+    ])
+    const client = createChatClient({ baseUrl: 'http://x/v1', model: 'm' }, fetch)
+    const res = await client.complete([{ role: 'user', content: 'x' }], [{ name: 'query_project', description: '', parameters: {} }], () => {})
+    expect(res.toolCalls).toEqual([{ id: 'c1', name: 'query_project', arguments: '{"view":"focus"}' }])
+  })
+
   it('POSTs to /chat/completions and parses content', async () => {
     const { fetch, calls } = stub({ choices: [{ message: { content: 'the focus is #2' } }] })
     const client = createChatClient({ baseUrl: 'http://localhost:1234/v1', model: 'gemma' }, fetch)

packages/core/src/agent/chat-client.ts

@@ -48,8 +48,12 @@ export interface CompletionResult {
   toolCalls: ToolCall[]
 }
 
+/** Called with each streamed content delta (final-prose streaming). */
+export type OnToken = (delta: string) => void
+
 export interface ChatClient {
-  complete(messages: ChatMessage[], tools?: ToolDecl[]): Promise<CompletionResult>
+  /** When `onToken` is given, the response streams (SSE) and each content delta is emitted. */
+  complete(messages: ChatMessage[], tools?: ToolDecl[], onToken?: OnToken): Promise<CompletionResult>
 }
 
 /** Map our message shape to the OpenAI wire shape. */
@@ -85,7 +89,7 @@ export function createChatClient(config: ModelConfig, fetchImpl: FetchLike): Cha
   const url = `${config.baseUrl.replace(/\/+$/, '')}/chat/completions`
 
   return {
-    async complete(messages, tools) {
+    async complete(messages, tools, onToken) {
       const body: Record<string, unknown> = {
         model: config.model,
         messages: messages.map(toWireMessage),
@@ -95,11 +99,13 @@ export function createChatClient(config: ModelConfig, fetchImpl: FetchLike): Cha
         body.tools = tools.map(toWireTool)
         body.tool_choice = 'auto'
       }
+      const stream = !!onToken
+      if (stream) body.stream = true
       const res = await fetchImpl(url, {
         method: 'POST',
         headers: {
           'Content-Type': 'application/json',
-          Accept: 'application/json',
+          Accept: stream ? 'text/event-stream' : 'application/json',
           ...(config.apiKey ? { Authorization: `Bearer ${config.apiKey}` } : {}),
         },
         body: JSON.stringify(body),
@@ -108,6 +114,8 @@ export function createChatClient(config: ModelConfig, fetchImpl: FetchLike): Cha
         const text = await res.text().catch(() => '')
         throw new Error(`model completion failed (${res.status}): ${text.slice(0, 200)}`)
       }
+      if (stream && res.body) return readStream(res.body, onToken!)
+
       const json = (await res.json()) as { choices?: { message: RawChoiceMessage }[] }
       const msg = json.choices?.[0]?.message
       return {
@@ -121,3 +129,56 @@ export function createChatClient(config: ModelConfig, fetchImpl: FetchLike): Cha
     },
   }
 }
+
+/** Streamed tool-call delta: name arrives first, arguments accumulate across chunks. */
+interface RawToolDelta {
+  index: number
+  id?: string
+  function?: { name?: string; arguments?: string }
+}
+
+/** Parse an OpenAI SSE stream: emit content deltas via onToken, accumulate the final result. */
+async function readStream(body: ReadableStream<Uint8Array>, onToken: OnToken): Promise<CompletionResult> {
+  const reader = body.getReader()
+  const decoder = new TextDecoder()
+  let buffer = ''
+  let content = ''
+  const toolAcc: { id: string; name: string; arguments: string }[] = []
+
+  const handle = (data: string) => {
+    if (data === '[DONE]') return
+    let chunk: { choices?: { delta?: { content?: string; tool_calls?: RawToolDelta[] } }[] }
+    try {
+      chunk = JSON.parse(data)
+    } catch {
+      return
+    }
+    const delta = chunk.choices?.[0]?.delta
+    if (!delta) return
+    if (delta.content) {
+      content += delta.content
+      onToken(delta.content)
+    }
+    for (const tc of delta.tool_calls ?? []) {
+      const slot = (toolAcc[tc.index] ??= { id: '', name: '', arguments: '' })
+      if (tc.id) slot.id = tc.id
+      if (tc.function?.name) slot.name = tc.function.name
+      if (tc.function?.arguments) slot.arguments += tc.function.arguments
+    }
+  }
+
+  for (;;) {
+    const { done, value } = await reader.read()
+    if (done) break
+    buffer += decoder.decode(value, { stream: true })
+    const lines = buffer.split('\n')
+    buffer = lines.pop() ?? ''
+    for (const line of lines) {
+      const t = line.trim()
+      if (t.startsWith('data:')) handle(t.slice(5).trim())
+    }
+  }
+  if (buffer.trim().startsWith('data:')) handle(buffer.trim().slice(5).trim())
+
+  return { content, toolCalls: toolAcc.filter((t) => t.name).map((t) => ({ id: t.id, name: t.name, arguments: t.arguments })) }
+}

packages/core/src/gitea/types.ts

@@ -31,6 +31,8 @@ export interface GiteaHttpResponse {
   status: number
   json(): Promise<unknown>
   text(): Promise<string>
+  /** Present on the real fetch Response; used for SSE streaming (chat). */
+  body?: ReadableStream<Uint8Array> | null
 }
 
 export type FetchLike = (url: string, init?: GiteaRequestInit) => Promise<GiteaHttpResponse>

packages/core/src/index.ts

@@ -80,7 +80,7 @@ export type {
 } from './calibration/calibration-v0.js'
 
 export { createChatClient } from './agent/chat-client.js'
-export type { ChatClient, ChatMessage, CompletionResult, ModelConfig, ToolCall, ToolDecl } from './agent/chat-client.js'
+export type { ChatClient, ChatMessage, CompletionResult, ModelConfig, OnToken, ToolCall, ToolDecl } from './agent/chat-client.js'
 export { pickModel } from './agent/model-router.js'
 export type { ModelRouter, TaskKind } from './agent/model-router.js'
 export { runAgentTurn } from './agent/agent-loop.js'