Never auto-abort a healthy wait for the model's next token

awaitingResponse flips true with no signal to tell "still coming" from
"never coming" apart, both right after submit and the instant a tool
batch resolves. Auto-abort now only fires on a stream that had already
started producing tokens and then went dead mid-flight; the awaiting
case still surfaces via the notice instead of killing the turn.

Adds regression coverage for a healthy post-tool-batch wait and for
live sub-agent progress under an outstanding task call, both of which
must never auto-abort.

Author: TheGreatAxios

docs/TUI.md

@@ -133,6 +133,14 @@ threshold, so a resumed session with already-stale activity shows the settled
 glyph immediately rather than alarming about silence the operator missed, and
 a stall that breaks and re-arms bursts again.
 
+Auto-abort (`shouldAbortForStall`) is reserved for a stream that had already
+started producing tokens and then went dead mid-flight — not for a run that
+is merely *awaiting* the model's next response (right after submit, or the
+instant a tool batch resolves and `awaitingResponse` flips back to true).
+That wait has no signal to tell "still coming" from "never coming" apart, so
+it is never auto-aborted no matter how long it runs; it still surfaces via
+the notice, keeping the operator in control of whether to give up on it.
+
 An idle session animates nothing at all: the monitor tick stops entirely
 rather than repainting an unchanging frame.
 

src/tui/stall-watchdog.test.ts

@@ -14,28 +14,21 @@ import {
 } from "./stall-watchdog.js"
 
 describe("shouldAbortForStall", () => {
+  // Mid-stream hang: tokens already flowed, then everything went silent —
+  // the one shape auto-abort is willing to act on. The generic guards
+  // (status, threshold, exemptions) are exercised against this base.
   const base = {
     status: "running" as const,
-    awaitingResponse: true,
+    awaitingResponse: false,
     lastActivityAt: 0,
     nowMs: STALL_TIMEOUT_MS,
     stallTimeoutMs: STALL_TIMEOUT_MS,
     isProcessing: true,
-    streamingType: null,
+    streamingType: "text" as const,
     activeToolCalls: [],
   }
 
-  test("a parallel fan-out with sibling tools still running is not a stall", () => {
-    const args = {
-      ...base,
-      activeToolCalls: ["call-2"],
-      lastActivityAt: 0,
-      nowMs: 20 * 60_000,
-    }
-    expect(shouldAbortForStall(args)).toBe(false)
-  })
-
-  test("aborts an awaiting run past the timeout", () => {
+  test("aborts a mid-stream hang past the timeout", () => {
     expect(shouldAbortForStall(base)).toBe(true)
   })
 
@@ -52,60 +45,89 @@ describe("shouldAbortForStall", () => {
     expect(shouldAbortForStall({ ...base, status: "stopping" })).toBe(false)
   })
 
-  // Two independent exemptions (a gate open on the operator, a sibling tool
-  // call still outstanding) must both keep exempting when combined — neither
-  // one's guard may accidentally require the other's condition to also hold.
-  test("a gate open and a sibling tool call each exempt alone, and together", () => {
-    const gateOnly = { ...base, status: "blocked" as const }
-    const toolCallOnly = { ...base, activeToolCalls: ["call-2"] }
-    const both = { ...base, status: "blocked" as const, activeToolCalls: ["call-2"] }
-
-    expect(shouldAbortForStall(gateOnly)).toBe(false)
-    expect(shouldAbortForStall(toolCallOnly)).toBe(false)
-    expect(shouldAbortForStall(both)).toBe(false)
-  })
-
   test("a settled turn with nothing in flight is not a stall", () => {
     expect(
       shouldAbortForStall({
         ...base,
-        awaitingResponse: false,
+        streamingType: null,
         isProcessing: false,
       }),
     ).toBe(false)
   })
 
   test("mid-thinking silence fires, recent thinking tokens do not", () => {
-    const thinking = {
-      ...base,
-      awaitingResponse: false,
-      streamingType: "thinking" as const,
-    }
+    const thinking = { ...base, streamingType: "thinking" as const }
     expect(shouldAbortForStall(thinking)).toBe(true)
     expect(
       shouldAbortForStall({ ...thinking, lastActivityAt: STALL_TIMEOUT_MS - 1 }),
     ).toBe(false)
   })
 
   test("mid-stream text hang aborts", () => {
-    expect(
-      shouldAbortForStall({
-        ...base,
-        awaitingResponse: false,
-        streamingType: "text",
-      }),
-    ).toBe(true)
+    expect(shouldAbortForStall(base)).toBe(true)
   })
 
   test("long tool runs are not stalls", () => {
+    expect(shouldAbortForStall({ ...base, streamingType: "tool" })).toBe(false)
+  })
+})
+
+// The other shape silence can take: awaiting the model's next response, with
+// no tokens yet — set right after submit and again the instant the last
+// outstanding tool call resolves (`turnStateOnSubmit`, the `tool.done`
+// handler). A slow model produces exactly this state for as long as it takes
+// to reply, so it is never auto-aborted, however long the silence — only the
+// notice may surface. This is the regression coverage for CL-5640.
+describe("shouldAbortForStall — awaiting the model's next token is never auto-aborted", () => {
+  const awaiting = {
+    status: "running" as const,
+    awaitingResponse: true,
+    lastActivityAt: 0,
+    nowMs: STALL_TIMEOUT_MS,
+    stallTimeoutMs: STALL_TIMEOUT_MS,
+    isProcessing: true,
+    streamingType: null,
+    activeToolCalls: [],
+  }
+
+  test("does not abort a run merely awaiting a response, however long", () => {
+    expect(shouldAbortForStall(awaiting)).toBe(false)
     expect(
-      shouldAbortForStall({
-        ...base,
-        awaitingResponse: false,
-        streamingType: "tool",
-      }),
+      shouldAbortForStall({ ...awaiting, nowMs: STALL_TIMEOUT_MS * 10 }),
+    ).toBe(false)
+  })
+
+  // Mirrors the tool.done handler: the last outstanding call just resolved,
+  // awaitingResponse flips true and streamingType resets to null, then the
+  // model itself takes a long-but-healthy while to start its next reply.
+  test("healthy post-tool-batch wait never auto-aborts", () => {
+    expect(shouldAbortForStall({ ...awaiting, activeToolCalls: [] })).toBe(
+      false,
+    )
+  })
+
+  test("a parallel fan-out with sibling tools still running is not a stall", () => {
+    expect(
+      shouldAbortForStall({ ...awaiting, activeToolCalls: ["call-2"] }),
     ).toBe(false)
   })
+
+  // Two independent exemptions (a gate open on the operator, a sibling tool
+  // call still outstanding) must both keep exempting when combined — neither
+  // one's guard may accidentally require the other's condition to also hold.
+  test("a gate open and a sibling tool call each exempt alone, and together", () => {
+    const gateOnly = { ...awaiting, status: "blocked" as const }
+    const toolCallOnly = { ...awaiting, activeToolCalls: ["call-2"] }
+    const both = {
+      ...awaiting,
+      status: "blocked" as const,
+      activeToolCalls: ["call-2"],
+    }
+
+    expect(shouldAbortForStall(gateOnly)).toBe(false)
+    expect(shouldAbortForStall(toolCallOnly)).toBe(false)
+    expect(shouldAbortForStall(both)).toBe(false)
+  })
 })
 
 describe("applyStallRecovery", () => {
@@ -232,8 +254,26 @@ describe("shouldNoticeStall", () => {
     expect(shouldNoticeStall({ ...base, nowMs: STALL_NOTICE_MS - 1 })).toBe(false)
   })
 
-  test("hands over to the abort once the run is aborted", () => {
-    expect(shouldNoticeStall({ ...base, nowMs: STALL_TIMEOUT_MS })).toBe(false)
+  test("hands over to the abort once a mid-stream hang is aborted", () => {
+    const midStream = {
+      ...base,
+      awaitingResponse: false,
+      streamingType: "text" as const,
+    }
+    expect(shouldNoticeStall({ ...midStream, nowMs: STALL_TIMEOUT_MS })).toBe(
+      false,
+    )
+  })
+
+  test("a healthy wait for the model's next token keeps noticing rather than handing over to an abort", () => {
+    // Unlike the mid-stream case above, this shape never reaches "abort" —
+    // see the shouldAbortForStall describe block above — so the notice keeps
+    // surfacing indefinitely instead of going silent once the old timeout
+    // would have fired.
+    expect(shouldNoticeStall({ ...base, nowMs: STALL_TIMEOUT_MS })).toBe(true)
+    expect(
+      shouldNoticeStall({ ...base, nowMs: STALL_TIMEOUT_MS * 10 }),
+    ).toBe(true)
   })
 
   test("a long tool run is not stuck", () => {
@@ -261,21 +301,41 @@ describe("the stall level the indicator reads", () => {
     repeating: false,
   }
 
-  test("quiet, notice and abort partition the same silence clock", () => {
-    expect(stallLevel({ ...base, nowMs: STALL_NOTICE_MS - 1 })).toBe("quiet")
+  test("quiet, notice and abort partition the same silence clock for a mid-stream hang", () => {
+    const midStream = { ...base, awaitingResponse: false, streamingType: "text" as const }
+    expect(stallLevel({ ...midStream, nowMs: STALL_NOTICE_MS - 1 })).toBe(
+      "quiet",
+    )
+    expect(stallLevel({ ...midStream, nowMs: STALL_NOTICE_MS })).toBe("notice")
+    expect(stallLevel({ ...midStream, nowMs: STALL_TIMEOUT_MS })).toBe("abort")
+  })
+
+  // Awaiting the model's next token (right after submit, or right after a
+  // tool batch resolves) never escalates to "abort" — see
+  // shouldAbortForStall's dedicated describe block — so this shape stays at
+  // "notice" indefinitely instead of handing over.
+  test("a healthy wait for the model's next token stays at notice, never abort", () => {
     expect(stallLevel({ ...base, nowMs: STALL_NOTICE_MS })).toBe("notice")
-    expect(stallLevel({ ...base, nowMs: STALL_TIMEOUT_MS })).toBe("abort")
+    expect(stallLevel({ ...base, nowMs: STALL_TIMEOUT_MS })).toBe("notice")
+    expect(stallLevel({ ...base, nowMs: STALL_TIMEOUT_MS * 10 })).toBe(
+      "notice",
+    )
   })
 
   test("the indicator keeps reading stalled across the abort threshold", () => {
     // The notice hands over to the abort so the two never speak at once, but
     // the phase must not flip back to healthy at the exact moment the run is
     // most stuck — that was the whole complaint the indicator answers.
-    expect(shouldNoticeStall({ ...base, nowMs: STALL_TIMEOUT_MS })).toBe(false)
-    expect(isStalledForDisplay({ ...base, nowMs: STALL_TIMEOUT_MS })).toBe(true)
-    expect(isStalledForDisplay({ ...base, nowMs: STALL_TIMEOUT_MS * 3 })).toBe(
-      true,
+    const midStream = { ...base, awaitingResponse: false, streamingType: "text" as const }
+    expect(shouldNoticeStall({ ...midStream, nowMs: STALL_TIMEOUT_MS })).toBe(
+      false,
     )
+    expect(
+      isStalledForDisplay({ ...midStream, nowMs: STALL_TIMEOUT_MS }),
+    ).toBe(true)
+    expect(
+      isStalledForDisplay({ ...midStream, nowMs: STALL_TIMEOUT_MS * 3 }),
+    ).toBe(true)
   })
 
   test("a repeating run is not a stall on any surface", () => {

src/tui/stall-watchdog.ts

@@ -104,9 +104,33 @@ function silentPastThreshold(
   )
 }
 
+/**
+ * Whether the run has gone silent while merely *awaiting* the model's next
+ * response — right after submit or the instant a tool batch resolves, before
+ * any token of the reply has arrived. `turnStateOnSubmit` and the `tool.done`
+ * handler both reset `streamingType` to null exactly when they flip
+ * `awaitingResponse` true, so this state can persist for as long as the model
+ * takes to start replying: a slow model or a long thinking pass, not
+ * necessarily a dead one. There is no signal available here to tell "still
+ * coming" from "never coming" apart, so this case is deliberately excluded
+ * from auto-abort and left to the notice instead — see `shouldAbortForStall`.
+ */
+function awaitingFirstToken(args: ShouldAbortForStallArgs): boolean {
+  return args.awaitingResponse && args.streamingType === null
+}
+
 // Pure decision helper: returns true when the run is genuinely stuck and should
 // be aborted. Extracted so the timeout logic is unit-testable without timers.
+//
+// Auto-abort is reserved for a stream that had already started producing
+// tokens and then went dead mid-flight — the one case silence cannot be
+// explained by "still waiting on the model." A long-but-healthy wait for the
+// model to start (right after submit, or right after a tool batch resolves)
+// is exempted here even past the timeout: it still surfaces via the notice
+// (`stallLevel` / `shouldNoticeStall`), but the operator stays in control of
+// whether to give up on it rather than having the turn discarded for them.
 export function shouldAbortForStall(args: ShouldAbortForStallArgs): boolean {
+  if (awaitingFirstToken(args)) return false
   return silentPastThreshold(args, args.stallTimeoutMs)
 }
 

src/tui/turn-monitor.test.ts

@@ -326,11 +326,14 @@ describe("stall watchdog", () => {
     })
   })
 
-  test("aborts and flashes after the stall timeout", async () => {
+  test("aborts and flashes once a mid-stream hang crosses the stall timeout", async () => {
     await withTestRenderer(async (h) => {
       const t: Harness = await setup(h)
       try {
         t.bridge.submit("build it", "immediate")
+        // Tokens actually started flowing, then everything went silent —
+        // the one shape auto-abort still acts on.
+        t.bridge.handle({ type: "inference.text.delta", data: { token: "ok" } })
         t.port.clear()
 
         t.advance(500)
@@ -352,6 +355,83 @@ describe("stall watchdog", () => {
     })
   })
 
+  // CL-5640: a healthy wait for the model to start its next reply — right
+  // after submit, or right after the last outstanding tool call resolves —
+  // must never be auto-aborted just because the parent stream is quiet. Only
+  // a stream that had already started producing tokens and then went dead
+  // (covered above) earns the abort; this shape gets the notice at most.
+  test("a long-but-healthy wait right after submit is never auto-aborted, only noticed", async () => {
+    await withTestRenderer(async (h) => {
+      const t: Harness = await setup(h)
+      try {
+        t.bridge.submit("build it", "immediate")
+        t.port.clear()
+
+        // No delta ever arrives — the model is just slow to start — held
+        // far past the stall timeout.
+        t.advance(20 * 60_000)
+        t.tick()
+        expect(t.port.calls).toEqual([])
+        expect(t.shell.statusFlash).toBe(STALL_NOTICE_MESSAGE)
+      } finally {
+        t.bridge.dispose()
+      }
+    })
+  })
+
+  test("a long-but-healthy wait right after a tool batch resolves is never auto-aborted", async () => {
+    await withTestRenderer(async (h) => {
+      const t: Harness = await setup(h)
+      try {
+        t.bridge.submit("build it", "immediate")
+        t.bridge.handle({
+          type: "inference.tool_call.end",
+          data: { name: "bash", callId: "c1" },
+        })
+        t.bridge.handle({
+          type: "tool.done",
+          data: { result: { callId: "c1" } },
+        })
+        t.port.clear()
+
+        // The last outstanding call resolved; the model just takes a long
+        // while to start its next reply. Held far past the stall timeout.
+        t.advance(20 * 60_000)
+        t.tick()
+        expect(t.port.calls).toEqual([])
+        expect(t.shell.statusFlash).toBe(STALL_NOTICE_MESSAGE)
+      } finally {
+        t.bridge.dispose()
+      }
+    })
+  })
+
+  // CL-5640: live sub-agent progress must keep the parent stream's silence
+  // exempt from abort even though the parent's own `task` call is the only
+  // thing in `activeToolCalls` — a future change to task-lifecycle handling
+  // must not silently drop this exemption.
+  test("live sub-agent progress under an outstanding task call is never auto-aborted", async () => {
+    await withTestRenderer(async (h) => {
+      const t: Harness = await setup(h)
+      try {
+        t.bridge.submit("build it", "immediate")
+        t.bridge.handle({
+          type: "inference.tool_call.end",
+          data: { name: "task", callId: "c1" },
+        })
+        t.port.clear()
+
+        // The parent stream stays quiet while the sub-agent works — far past
+        // the stall timeout.
+        t.advance(20 * 60_000)
+        t.tick()
+        expect(t.port.calls).toEqual([])
+      } finally {
+        t.bridge.dispose()
+      }
+    })
+  })
+
   test("an open gate is exempt no matter how long the operator takes", async () => {
     await withTestRenderer(async (h) => {
       const t: Harness = await setup(h)