diff --git a/src/main/config.ts b/src/main/config.ts
index 24b4420d7..011834a8a 100644
--- a/src/main/config.ts
+++ b/src/main/config.ts
@@ -58,6 +58,16 @@ export interface ScheduledMission {
    *  inbox/outbox mtimes, any PTY output) has moved in this many ms. Default
    *  ~5 min. NOT derived from registry.status (which never transitions in main). */
   quietThresholdMs?: number;
+  /** Heartbeat only. Default true. When the floor is quiet and god's inbox has
+   *  no real (non-scheduler) mail, a beat normally still re-engages god just
+   *  because the floor went quiet. With this on, that re-engage is additionally
+   *  gated on tasks.json having at least one 'doing' card — a quiet floor with
+   *  work still in flight may be a stall worth a look; a quiet floor with
+   *  nothing doing has nothing for god to review, so the beat is a no-op and
+   *  re-arms on the normal (non-back-off) cadence instead of waking god. Set to
+   *  false to restore the original behaviour where any quiet floor re-engages.
+   *  Reversible from config.json without a rebuild. */
+  suppressWhenIdle?: boolean;
 }
 
 /** The built-in hourly ops standup: god reviews who's doing what + whether tasks
@@ -107,7 +117,8 @@ export const HEARTBEAT_MISSION: ScheduledMission = {
     'if the work is genuinely done.',
   enabled: false,
   kind: 'heartbeat',
-  quietThresholdMs: 300_000
+  quietThresholdMs: 300_000,
+  suppressWhenIdle: true
 };
 
 /** The dedicated auto-compact MAINTENANCE schedule (maint-1). DECOUPLED from the
diff --git a/src/main/heartbeatPolicy.ts b/src/main/heartbeatPolicy.ts
new file mode 100644
index 000000000..b1218a1be
--- /dev/null
+++ b/src/main/heartbeatPolicy.ts
@@ -0,0 +1,57 @@
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+
+/**
+ * Pure re-engage decision for one heartbeat beat, extracted out of index.ts's
+ * beat() so it can be tested directly (index.ts pulls in Electron and cannot
+ * be evaluated outside the main process). Node builtins only, no Electron.
+ */
+
+export interface ReengageInputs {
+  /** Unread, non-scheduler messages in god's inbox (see godActionableInboxCount
+   *  in index.ts). Always wins: a worker's reply must never sit unread. */
+  actionable: number;
+  /** Whether the floor has gone quiet for at least the mission's
+   *  quietThresholdMs (see isFloorQuiet in index.ts). */
+  quiet: boolean;
+  /** Count of tasks.json cards with status 'doing'. Only meaningful when
+   *  `quiet` is true and `actionable` is 0 — see doingTaskCount below, whose
+   *  read failures are deliberately biased so this is never a false zero. */
+  doingCount: number;
+  /** Heartbeat mission config knob (ScheduledMission.suppressWhenIdle,
+   *  default true). true: a quiet floor with nothing 'doing' has nothing for
+   *  god to review, so the beat does not re-engage. false: restores the
+   *  original behaviour, where any quiet floor re-engages. */
+  suppressWhenIdle: boolean;
+}
+
+/** Should this beat re-engage god? Real inbox mail always does. Otherwise: an
+ *  active (non-quiet) floor never does. A quiet floor re-engages unless
+ *  suppressWhenIdle is on AND nothing is 'doing' — a quiet floor with work in
+ *  flight may be a stall worth waking god for; a quiet floor with nothing
+ *  doing has nothing for god to do. */
+export function shouldReengage(inputs: ReengageInputs): boolean {
+  if (inputs.actionable > 0) return true;
+  if (!inputs.quiet) return false;
+  if (!inputs.suppressWhenIdle) return true;
+  return inputs.doingCount > 0;
+}
+
+/** Count of tasks.json cards with status 'doing', read directly from
+ *  `<root>/tasks.json`. A missing root, a missing file, unparsable JSON, or a
+ *  `tasks` field that is not an array are all treated as "at least one doing
+ *  card" (returns 1) rather than 0 — the read is only ever used to decide
+ *  whether a quiet floor is safe to leave alone, so a ledger we cannot trust
+ *  must fail toward waking god, never toward silence. An empty-but-valid
+ *  tasks array is a genuine, trustworthy zero. */
+export function doingTaskCount(root: string | null): number {
+  if (!root) return 1;
+  try {
+    const raw = readFileSync(join(root, 'tasks.json'), 'utf8');
+    const parsed = JSON.parse(raw) as { tasks?: unknown };
+    if (!Array.isArray(parsed?.tasks)) return 1;
+    return parsed.tasks.filter((t: { status?: unknown }) => t && t.status === 'doing').length;
+  } catch {
+    return 1;
+  }
+}
diff --git a/src/main/index.ts b/src/main/index.ts
index cbd984918..65e2c0061 100644
--- a/src/main/index.ts
+++ b/src/main/index.ts
@@ -30,6 +30,7 @@ import { saveAskAttachment } from './askAttachments';
 import { HiveManager, type AgentMeta, type HiveMessage, type HiveTask } from './hive';
 import { HookServer } from './hooks';
 import { CircuitBreaker, type BreakerInput } from './breaker';
+import { shouldReengage, doingTaskCount } from './heartbeatPolicy';
 import type { UsageProvider } from './usage';
 import { MemoryManager } from './memory';
 import { testHindsightConnection } from './hindsightAdapter';
@@ -1346,9 +1347,23 @@ function armHeartbeat(m: ScheduledMission): void {
       // waiting in god's inbox — the latter is independent of floor-quiet so a
       // worker's reply doesn't sit unread while other agents keep the floor busy.
       const actionable = godActionableInboxCount();
-      if (isFloorQuiet(quiet) || actionable > 0) {
+      const floorQuiet = isFloorQuiet(quiet);
+      const suppressWhenIdle = m.suppressWhenIdle ?? true;
+      // tasks.json is only read when it can actually change the outcome: a
+      // quiet floor, no actionable mail, and the knob on — every other case is
+      // decided by actionable/floorQuiet alone, so skip the extra read.
+      const doingCount = (floorQuiet && actionable === 0 && suppressWhenIdle)
+        ? doingTaskCount(hive.root())
+        : 0;
+      if (shouldReengage({ actionable, quiet: floorQuiet, doingCount, suppressWhenIdle })) {
         reengageGod(buildHeartbeatDigest(quiet, actionable));
         next = Math.round(base * 2.5);            // back off after re-engaging
+      } else if (floorQuiet) {
+        // Would have re-engaged under the old (pre-suppressWhenIdle) semantics —
+        // the floor is quiet and there is no actionable mail — but nothing is
+        // 'doing', so there is nothing here for god to review. Stay quiet and
+        // re-arm on the normal cadence (no back-off: this beat did nothing).
+        hive.appendLog({ kind: 'heartbeat-suppressed', reason: 'quiet-no-doing-cards', actionable, doingCount });
       } else if (looksStuck(quiet)) {
         next = Math.max(30_000, Math.round(base / 4)); // tighten when an agent is wedged
       }
diff --git a/test/heartbeat-policy.test.cjs b/test/heartbeat-policy.test.cjs
new file mode 100644
index 000000000..dc736d3e4
--- /dev/null
+++ b/test/heartbeat-policy.test.cjs
@@ -0,0 +1,97 @@
+'use strict';
+
+/**
+ * Pure decision logic for one heartbeat beat: whether to re-engage god, and how
+ * many tasks.json cards are 'doing' (the signal that distinguishes "quiet floor,
+ * nothing in flight" from "quiet floor, a stall in progress"). Extracted out of
+ * index.ts's beat() so it can be exercised directly instead of only through the
+ * Electron-only main process.
+ */
+
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const os = require('node:os');
+const path = require('node:path');
+const loadTs = require('./load-ts.cjs');
+
+const { shouldReengage, doingTaskCount } = loadTs('src/main/heartbeatPolicy.ts');
+
+function tmpRoot(t) {
+  const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'md-heartbeat-policy-'));
+  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  return dir;
+}
+
+function writeTasks(root, tasks) {
+  fs.writeFileSync(path.join(root, 'tasks.json'), JSON.stringify({ tasks }), 'utf8');
+}
+
+// ─── shouldReengage ────────────────────────────────────────────────────────
+
+test('actionable inbox mail always re-engages, regardless of quiet/doing/knob', () => {
+  assert.equal(shouldReengage({ actionable: 1, quiet: false, doingCount: 0, suppressWhenIdle: true }), true);
+  assert.equal(shouldReengage({ actionable: 1, quiet: true, doingCount: 0, suppressWhenIdle: false }), true);
+  assert.equal(shouldReengage({ actionable: 3, quiet: false, doingCount: 5, suppressWhenIdle: true }), true);
+});
+
+test('an active (non-quiet) floor with no actionable mail never re-engages', () => {
+  assert.equal(shouldReengage({ actionable: 0, quiet: false, doingCount: 0, suppressWhenIdle: true }), false);
+  assert.equal(shouldReengage({ actionable: 0, quiet: false, doingCount: 5, suppressWhenIdle: true }), false);
+  assert.equal(shouldReengage({ actionable: 0, quiet: false, doingCount: 0, suppressWhenIdle: false }), false);
+});
+
+test('quiet + no doing cards + suppression on => does NOT re-engage (the new behaviour)', () => {
+  assert.equal(shouldReengage({ actionable: 0, quiet: true, doingCount: 0, suppressWhenIdle: true }), false);
+});
+
+test('quiet + at least one doing card + suppression on => DOES re-engage (possible stall)', () => {
+  assert.equal(shouldReengage({ actionable: 0, quiet: true, doingCount: 1, suppressWhenIdle: true }), true);
+  assert.equal(shouldReengage({ actionable: 0, quiet: true, doingCount: 4, suppressWhenIdle: true }), true);
+});
+
+test('knob off restores the old behaviour: any quiet floor re-engages regardless of doing cards', () => {
+  assert.equal(shouldReengage({ actionable: 0, quiet: true, doingCount: 0, suppressWhenIdle: false }), true);
+  assert.equal(shouldReengage({ actionable: 0, quiet: true, doingCount: 7, suppressWhenIdle: false }), true);
+});
+
+// ─── doingTaskCount ────────────────────────────────────────────────────────
+
+test('counts only cards with status doing, ignoring todo/blocked/done', (t) => {
+  const root = tmpRoot(t);
+  writeTasks(root, [
+    { id: '1', status: 'todo' },
+    { id: '2', status: 'doing' },
+    { id: '3', status: 'blocked' },
+    { id: '4', status: 'doing' },
+    { id: '5', status: 'done' }
+  ]);
+  assert.equal(doingTaskCount(root), 2);
+});
+
+test('an empty (legitimate) task list counts as zero doing cards', (t) => {
+  const root = tmpRoot(t);
+  writeTasks(root, []);
+  assert.equal(doingTaskCount(root), 0);
+});
+
+test('a missing tasks.json fails toward "has doing cards", never toward silence', (t) => {
+  const root = tmpRoot(t); // no tasks.json written at all
+  assert.equal(doingTaskCount(root) > 0, true);
+});
+
+test('a corrupt tasks.json (unparsable JSON) fails toward "has doing cards"', (t) => {
+  const root = tmpRoot(t);
+  fs.writeFileSync(path.join(root, 'tasks.json'), '{ not valid json', 'utf8');
+  assert.equal(doingTaskCount(root) > 0, true);
+});
+
+test('a malformed tasks.json (tasks is not an array) fails toward "has doing cards"', (t) => {
+  const root = tmpRoot(t);
+  fs.writeFileSync(path.join(root, 'tasks.json'), JSON.stringify({ tasks: 'nope' }), 'utf8');
+  assert.equal(doingTaskCount(root) > 0, true);
+});
+
+test('a null hive root (hive disabled) fails toward "has doing cards"', () => {
+  assert.equal(doingTaskCount(null) > 0, true);
+});