diff --git a/CHANGELOG.md b/CHANGELOG.md
index a283efa..72f2d2e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,24 @@ new version heading in the same commit.
 
 ## [Unreleased]
 
+## [0.193.1] — 2026-07-14
+### Fixed
+- **Chat replies no longer stall on "thinking…" forever.** The v1 Chat surface delivered a follow-up by
+  typing it into a warm resident TUI pane (`deliverToResident`); when that pane had been reaped or the
+  keystrokes didn't trigger a turn, the message was silently lost and the UI spun indefinitely (the DB row
+  still read `running`). Replies now go through **`TerminalManager.chatSend`** — every turn is a clean,
+  self-terminating **headless resume** run seeded with the message as the prompt (reliable turn trigger,
+  not injected keystrokes), and `chat/start` is likewise a headless one-shot. The run tears down at
+  turn-end, so the UI's "thinking…" is driven by *real* pane liveness and can't hang; a genuinely stalled
+  turn shows a **Resend**, and a reply sent while the prior turn is still generating returns `busy` (the
+  draft is kept). Trade: a cold start per turn — removed properly by the SDK runtime (see below). The
+  PreToolUse gate still governs every effect. (`src/terminal.ts`, `src/server.ts`, `web/src/App.tsx`,
+  `web/src/lib/api.ts`.)
+### Added
+- **`docs/sdk-chat-runtime-plan.md`** — the proposed v2: drive the chat surface via the Claude Agent SDK
+  (`query()` + `includePartialMessages` + `canUseTool` → the existing gateway) for token streaming and a
+  first-class approval hook, running beside the CLI/tmux runtime. Not started; greenlight before building.
+
 ## [0.193.0] — 2026-07-14
 ### Added
 - **Transfer a session to another owner.** A session's accountable human — its `run_as` — can now be
diff --git a/docs/sdk-chat-runtime-plan.md b/docs/sdk-chat-runtime-plan.md
new file mode 100644
index 0000000..c01ac47
--- /dev/null
+++ b/docs/sdk-chat-runtime-plan.md
@@ -0,0 +1,89 @@
+# Plan: SDK-driven chat runtime (native chat v2)
+
+**Status:** proposed — not started. This is the "do it right" successor to the hardened v1 chat
+surface (`src/edge/conversation.ts` + the Chat page + `TerminalManager.chatSend`). Greenlight before
+building.
+
+## Why
+
+The v1 Chat page drives Claude the only way agent-os currently can: it spawns a real `claude` CLI in a
+detached **tmux** pane, seeds each turn as a resume prompt, and **reads the internal transcript JSONL**
+for display. That works, but it inherits three structural limits:
+
+1. **Fragile driver.** Keeping a live TUI pane warm and injecting turns is racy (the 2026-07-14 stuck
+   "thinking…" bug). v1 hardens this by making every turn a self-terminating headless resume — reliable,
+   but it **cold-starts Claude per turn** (no warm latency) and can never token-stream.
+2. **No streaming.** Display is message-level polling (2 s). Non-technical users read a chat app; live
+   typing would feel materially better.
+3. **Volatile display source.** The transcript JSONL under `~/.claude/projects/**` is undocumented and
+   Anthropic-internal — it can change shape without notice, and it has **no approval hook** (a tool is
+   already executed by the time it lands in the transcript; agent-os only governs it because the
+   *separate* PreToolUse gate hook fired first).
+
+The **Claude Agent SDK** (TS/Python, officially supported) removes all three: a typed, documented event
+stream with token deltas (`includePartialMessages`) and a first-class programmatic approval callback
+(`canUseTool`). See `docs/agent-mcp-tools.md` and the research notes in the v1 PR.
+
+## Principle preserved
+
+The one invariant does not move: **every side effect still passes one mediated gateway.** Today that
+choke point is the gate-hook script → `/api/gate` → the 7-step gateway. In v2 it becomes the SDK's
+`canUseTool(tool, input)` callback → the **same** `gateway.ts` (Policy → Approvals → Budget → Identity →
+Idempotency → Audit) → allow/deny. Mechanism changes from a shell hook to an in-process callback; the
+trust boundary is identical.
+
+## Architecture — a second runtime, beside the CLI one (not a replacement)
+
+The CLI+tmux runtime stays: it's what gives **attachable terminals** (ttyd take-over, the shared proxy,
+the real TUI for engineers). The SDK runtime is **additive**, selected only for the chat surface:
+
+```
+Chat page ──SSE── /api/chat/stream ──▶ SdkChatRuntime (new)
+                                        │  @anthropic-ai/claude-agent-sdk `query()`
+                                        │  includePartialMessages → stream deltas out as SSE
+                                        │  canUseTool ─────────────▶ gateway.ts (unchanged core)
+                                        │  mcpServers/env ◀──────── reuse per-session injection
+                                        └─ typed messages → the fuller renderer (Phase 2 of v1)
+```
+
+- **Sessions:** an `SdkChatRuntime` holds one SDK `query()` conversation per chat session (resumable via
+  the SDK's session id), replacing the tmux pane + resume-per-turn. No pane lifecycle, no reaper.
+- **Streaming out:** a new `GET /api/chat/:id/stream` SSE endpoint forwards `stream_event` deltas
+  (`content_block_delta` text/tool-input) so the browser renders live typing and tool cards as they form.
+- **Governance in:** `canUseTool` awaits the gateway. A `pending` (needs a human) suspends the promise
+  and posts the **same** approval card the console already renders inline — no second approval system.
+- **Identity / secrets / MCP:** reuse the existing per-session wiring (`injectShellSecrets`,
+  `injectMemberGithub`, `buildMcpConfigJson`) but feed it to the SDK via `options.env` + `options.mcpServers`
+  instead of the launcher env. This is the bulk of the porting work.
+- **Rendering:** the SDK's typed message stream feeds the completeness pass (thinking, diffs, todos,
+  sub-agents, images) — the renderer becomes provider-stable instead of scraping JSONL.
+
+## Risks / open questions (resolve during a spike)
+
+1. **`canUseTool` parity with the gate hook** — confirm it fires for *every* governed surface (Bash,
+   file writes, each MCP tool) and can enforce the crown-jewel **deny** rules. This is the gating risk;
+   if a tool class bypasses `canUseTool`, governance regresses. Spike this first.
+2. **Subprocess vs in-process** — the SDK can run the agent loop in-process (Node) or spawn the CLI.
+   In-process is cleanest for streaming but changes the failure/isolation model; the Linux uid-isolation
+   path (`AOS_UID_ISOLATION`) assumes a spawned process. Decide per deployment.
+3. **Two runtimes to maintain** — chat on the SDK, terminals on the CLI. Acceptable (different surfaces,
+   different needs) but a real cost.
+4. **No ttyd attach for SDK sessions** — a native chat doesn't need it, but "open in terminal" wouldn't
+   apply to an SDK session. Keep the two surfaces distinct.
+
+## Rollout
+
+1. **Spike (1–2 d):** one agent, `query()` + `includePartialMessages` + `canUseTool` → log-only gateway
+   call. Prove tool-call coverage/parity and streaming end-to-end. Kill-criteria: any governed tool that
+   `canUseTool` can't see.
+2. **Wire governance:** `canUseTool` → real `gateway.ts`; approvals suspend/resume via the existing store.
+3. **Port per-session injection** (secrets/GitHub/MCP) to SDK options.
+4. **SSE + renderer:** stream deltas to the Chat page; land the completeness renderer.
+5. **Flag + coexist:** `AOS_SDK_CHAT` selects the SDK runtime for the chat surface only; CLI/tmux stays
+   the default everywhere else. Graduate once parity is proven.
+
+## Relationship to v1
+
+v1 (hardened, transcript-driven) stays shippable and is the fallback. v2 swaps the **driver** and
+**display source** under the same Chat page and the same gateway; the page, the approval cards, and the
+session model are largely reused.
diff --git a/package-lock.json b/package-lock.json
index b1f9712..5b2c272 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "agent-os",
-  "version": "0.193.0",
+  "version": "0.193.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "agent-os",
-      "version": "0.193.0",
+      "version": "0.193.1",
       "license": "MIT",
       "bin": {
         "agent-os": "bin/agent-os"
diff --git a/package.json b/package.json
index 9386ab6..03446ff 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "agent-os",
-  "version": "0.193.0",
+  "version": "0.193.1",
   "description": "A generic, governed operating system for running autonomous agents safely across brands. Ships with a local web console.",
   "license": "MIT",
   "type": "commonjs",
diff --git a/src/server.ts b/src/server.ts
index 63a7e04..34928ca 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -1906,8 +1906,10 @@ async function handle(os: AgentOS, tm: TerminalManager, autos: Automations, req:
     const message = String(b.message || '').trim();
     if (!agent || !message) return sendJson(res, 400, { error: 'agent and message are required' });
     if (!os.team.canRun(me, agent)) return sendJson(res, 403, { error: `you are not assigned to run "${agent}"` });
-    // spawnedBy=chat provenance, runAs=me (accountable human for the turn), resident=true.
-    const s = tm.createSession(agent, chatTitle(message, agent), message, `chat:${me.id}`, false, undefined, undefined, me.id, undefined, true);
+    // Provenance chat:me, runAs=me (accountable human). HEADLESS one-shot (not resident): the greeting
+    // turn runs then tears itself down, so every subsequent turn is a clean headless resume (chatSend) —
+    // no warm pane to race/reap, and `alive` stays honest. See TerminalManager.chatSend.
+    const s = tm.createSession(agent, chatTitle(message, agent), message, `chat:${me.id}`, true, undefined, undefined, me.id, undefined, false);
     return sendJson(res, 200, { id: s.id, tmux: s.tmux });
   }
   // Read the friendly conversation timeline for a session (poll this like the rest of the console).
@@ -1921,9 +1923,9 @@ async function handle(os: AgentOS, tm: TerminalManager, autos: Automations, req:
     const convo = claudeId ? readConversation(claudeId) : { turns: [], found: false };
     return sendJson(res, 200, { agent, ...convo });
   }
-  // Reply into a session (the human's next turn). Warm path types into the live resident pane; cold
-  // path (a reaped session) resumes the SAME transcript seeded with the message — identical to a Slack
-  // thread follow-up. The replier becomes the accountable run-as for this turn.
+  // Reply into a chat session (the human's next turn) as a clean, self-terminating headless resume run
+  // seeded with the message. `busy` (409) means the prior turn is still generating — the caller keeps the
+  // draft and asks the human to resend shortly. The replier is the accountable run-as for this turn.
   const chatReplyMatch = p.match(/^\/api\/sessions\/([\w-]+)\/reply$/);
   if (method === 'POST' && chatReplyMatch) {
     const id = chatReplyMatch[1];
@@ -1932,9 +1934,10 @@ async function handle(os: AgentOS, tm: TerminalManager, autos: Automations, req:
     const b = await readBody(req);
     const message = String(b.message || '').trim();
     if (!message) return sendJson(res, 400, { error: 'message is required' });
-    if (tm.deliverToResident(id, message)) return sendJson(res, 200, { status: 'delivered' });
-    if (tm.reviveResident(id, message, me.id)) return sendJson(res, 200, { status: 'revived' });
-    return sendJson(res, 409, { error: 'this session could not accept the message' });
+    const r = tm.chatSend(id, message, me.id);
+    if (r === 'busy') return sendJson(res, 409, { status: 'busy', error: 'the agent is still working on the previous message — resend in a moment' });
+    if (r === 'error') return sendJson(res, 409, { error: 'this session could not accept the message' });
+    return sendJson(res, 200, { status: 'sent' });
   }
   // Session activity: "which agent-os primitives did this run use?" — the session's audit stream,
   // classified into a chronological timeline + a grouped count summary. Same visibility as the terminal
diff --git a/src/terminal.ts b/src/terminal.ts
index d609c9e..ca43e04 100644
--- a/src/terminal.ts
+++ b/src/terminal.ts
@@ -1194,6 +1194,40 @@ export class TerminalManager {
     return true;
   }
 
+  /**
+   * Send the human's next turn into a NATIVE-CONSOLE chat session. Unlike Slack's warm send-keys path
+   * (`deliverToResident`), every turn here is a clean, SELF-TERMINATING governed run: a HEADLESS in-place
+   * resume of the same transcript, seeded with the message as the prompt. This is the deliberate trade the
+   * "harden" pass makes over the warm-pane model — the message is the launch prompt (reliably starts a
+   * turn, vs. injected keystrokes that may not), and the run tears itself down at turn-end so `alive`
+   * reflects reality (no perpetual "thinking…" when a pane dies silently). Cost: a cold start per turn;
+   * v2 (Agent SDK runtime) removes that. The PreToolUse gate hook still governs every effect.
+   *
+   * Returns: 'busy' (a prior turn is still running — the caller asks the human to resend shortly, so we
+   * never double-launch two claudes on one transcript), 'sent' (a fresh resume run was launched), or
+   * 'error' (unknown / non-resumable session).
+   */
+  chatSend(sessionId: string, message: string, runAs?: string): 'sent' | 'busy' | 'error' {
+    const row = this.db.prepare('SELECT agent, secret, claude_session_id, run_as, spawned_by FROM term_sessions WHERE id = ?')
+      .get<{ agent: string; secret: string | null; claude_session_id: string | null; run_as: string | null; spawned_by: string | null }>(sessionId);
+    if (!row || !row.claude_session_id) return 'error';
+    const body = (message || '').trim();
+    if (!body) return 'error';
+    if (this.isAlive(sessionId)) return 'busy'; // a turn is still generating — don't launch a competing run
+    const actingMember = runAs ?? row.run_as ?? undefined;
+    const hasSlack = !!this.db.prepare('SELECT 1 FROM slack_threads WHERE session_id = ?').get(sessionId);
+    const hasDiscord = !!this.db.prepare('SELECT 1 FROM discord_threads WHERE session_id = ?').get(sessionId);
+    this.db.prepare("UPDATE term_sessions SET status = 'running', headless = 1, resident = 0, task = ?, run_as = ?, last_activity = ?, updated_at = ? WHERE id = ?")
+      .run(body, actingMember ?? row.run_as ?? null, Date.now(), Date.now(), sessionId);
+    this.audit(sessionId, row.agent, 'chat.turn', { runAs: actingMember ?? null });
+    this.launchClaudeCode({
+      id: sessionId, agent: row.agent, task: body, secret: row.secret ?? randomBytes(24).toString('hex'),
+      actingMember, spawnedBy: row.spawned_by ?? undefined, hasSlack, hasDiscord,
+      headless: true, resident: false, resume: true, claudeSessionId: row.claude_session_id,
+    });
+    return 'sent';
+  }
+
   /**
    * "Take over" an unattended run: CLAIM its live, attachable TUI so a human can watch and steer — with
    * ZERO disruption. Unattended automation/task runs are now a real interactive claude in a detached tmux
diff --git a/web/src/App.tsx b/web/src/App.tsx
index 876048a..f34fc80 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -2854,10 +2854,15 @@ function ChatPage({ agents, sessions, messages, selected, onSelect }: {
   // Conversation timeline for the selected session (polled).
   const [convo, setConvo] = useState<ChatTurn[]>([])
   const [found, setFound] = useState(false)
+  // Turn tracking: when we send, record the time + the agent-turn count then, so we can tell "still
+  // working" from "the run ended without replying" — and never spin "thinking…" forever.
+  const [sentAt, setSentAt] = useState<number | null>(null)
+  const [awaitBase, setAwaitBase] = useState(0)
+  const [lastSent, setLastSent] = useState('')
   const scrollRef = useRef<HTMLDivElement>(null)
 
   useEffect(() => {
-    if (!selected) { setConvo([]); setFound(false); return }
+    if (!selected) { setConvo([]); setFound(false); setSentAt(null); return }
     let stop = false
     const poll = async () => {
       const r = await api.conversation(selected)
@@ -2875,7 +2880,20 @@ function ChatPage({ agents, sessions, messages, selected, onSelect }: {
   const pending = messages.filter((m) => m.sessionId === selected && (m.type === 'approval' || m.type === 'question') && (m.status ?? 'pending') === 'pending')
   const agentOf = (id?: string) => chatAgents.find((a) => a.id === id) || agents.find((a) => a.id === id)
   const activeAgent = agentOf(active?.agent)
-  const working = !!active && (active.alive ?? active.status === 'running')
+  // A turn is only ever "live" while the run's pane is actually alive — the honest signal a headless turn
+  // gives us (it tears down at turn-end). `agentTurns` = replies+activity so far, so we can detect a new
+  // agent turn landing after a send.
+  const alive = !!active?.alive
+  const agentTurns = convo.filter((t) => t.kind !== 'user').length
+  const gotReply = sentAt != null && agentTurns > awaitBase
+  // Clear the awaiting flag the moment a fresh agent turn arrives.
+  useEffect(() => { if (gotReply) setSentAt(null) }, [gotReply])
+  const awaiting = sentAt != null
+  // Stalled = we sent, the run is no longer alive, and enough time passed for a cold start to have booted,
+  // yet no new agent turn appeared. Shows a Resend instead of an endless spinner.
+  const stalled = awaiting && !alive && Date.now() - (sentAt ?? 0) > 12_000
+  const thinking = awaiting && !stalled
+  const working = alive || thinking
 
   const startChat = async () => {
     const agent = newAgent || chatAgents[0]?.id
@@ -2898,7 +2916,23 @@ function ChatPage({ agents, sessions, messages, selected, onSelect }: {
     setDraft('')
     const r = await api.reply(selected, message)
     setBusy(false)
-    if (r.error) setErr(r.error)
+    if (r.status === 'busy') { setErr('The agent is still working — resend in a moment.'); setDraft(message); return }
+    if (r.error) { setErr(r.error); return }
+    // Sent: begin awaiting a reply (baseline = agent turns so far).
+    setLastSent(message)
+    setAwaitBase(convo.filter((t) => t.kind !== 'user').length)
+    setSentAt(Date.now())
+  }
+
+  const resend = async () => {
+    if (!selected || !lastSent || busy) return
+    setBusy(true); setErr('')
+    const r = await api.reply(selected, lastSent)
+    setBusy(false)
+    if (r.status === 'busy') { setErr('Still working — try again in a moment.'); return }
+    if (r.error) { setErr(r.error); return }
+    setAwaitBase(convo.filter((t) => t.kind !== 'user').length)
+    setSentAt(Date.now())
   }
 
   const onKey = (e: ReactKeyboardEvent, fn: () => void) => {
@@ -2987,9 +3021,14 @@ function ChatPage({ agents, sessions, messages, selected, onSelect }: {
                   ? <ActivityCard key={i} turn={t} />
                   : <ChatBubble key={i} turn={t} agentIcon={activeAgent?.icon} />,
               )}
-              {working && convo.length > 0 && convo[convo.length - 1].kind === 'user' && (
-                <div className="pl-9 text-xs text-muted-foreground">thinking…</div>
-              )}
+              {stalled ? (
+                <div className="flex items-center gap-2 pl-1 text-xs text-muted-foreground">
+                  <span>No reply came back.</span>
+                  <button className="font-medium text-primary hover:underline" onClick={resend}>Resend</button>
+                </div>
+              ) : thinking ? (
+                <div className="pl-9 text-xs text-muted-foreground animate-pulse">thinking…</div>
+              ) : null}
             </div>
 
             {/* Inline approvals / questions — the trust surface, in plain language */}
diff --git a/web/src/lib/api.ts b/web/src/lib/api.ts
index 30f3998..d73d4c8 100644
--- a/web/src/lib/api.ts
+++ b/web/src/lib/api.ts
@@ -1023,9 +1023,10 @@ export const api = {
   /** Start a chat with an agent — spawns a warm resident session. Returns its id. */
   startChat: (agent: string, message: string) =>
     call<{ id?: string; tmux?: string; error?: string }>('POST', '/api/chat/start', { agent, message }),
-  /** Send the human's next turn into a chat session (warm deliver, else resume). */
+  /** Send the human's next turn into a chat session — a clean headless resume run. `busy` = a prior
+   *  turn is still generating (keep the draft, resend shortly). */
   reply: (id: string, message: string) =>
-    call<{ status?: 'delivered' | 'revived'; error?: string }>('POST', `/api/sessions/${id}/reply`, { message }),
+    call<{ status?: 'sent' | 'busy'; error?: string }>('POST', `/api/sessions/${id}/reply`, { message }),
   /** Upload a pasted/dropped/picked file (ANY type) into a live session; the server saves it in the
    *  agent's folder and types the path into the running claude. `dataB64` is base64 (no data: prefix);
    *  `ext` e.g. 'pdf'; `name` is the original filename, preserved when given. */