fix: preserve automation queue safety limit

lib/automation-control.js

@@ -14,10 +14,20 @@
     return Array.isArray(value) ? value : [];
   }
 
+  function normalizeQueueLimit(value) {
+    const isNumber = typeof value === 'number';
+    const isString = typeof value === 'string';
+    if (!isNumber && !isString) return 15000;
+    if (isString && value.trim() === '') return 15000;
+    const number = Number(value);
+    if (!Number.isFinite(number) || number < 0) return 15000;
+    if (number === 0 && isString && value.trim() !== '0') return 15000;
+    return Math.floor(number);
+  }
+
   function normalizeAutomationSettings(value = {}) {
     const settings = asObject(value);
-    const rawLimit = Number(settings.queueLimitJobs);
+    const queueLimitJobs = normalizeQueueLimit(settings.queueLimitJobs);
-    const queueLimitJobs = Number.isFinite(rawLimit) && rawLimit >= 0 ? Math.floor(rawLimit) : 15000;
     const rawInterval = Number(settings.reconcileIntervalMinutes);
     return {
       queueLimitJobs,
@@ -39,8 +49,7 @@
     );
     const rawCurrentJobCount = Number(value.currentJobCount);
     const currentJobCount = Number.isFinite(rawCurrentJobCount) ? Math.max(0, Math.floor(rawCurrentJobCount)) : 0;
-    const rawQueueLimitJobs = value.queueLimitJobs === undefined ? 15000 : Number(value.queueLimitJobs);
+    const queueLimitJobs = normalizeQueueLimit(value.queueLimitJobs);
-    const queueLimitJobs = Number.isFinite(rawQueueLimitJobs) && rawQueueLimitJobs >= 0 ? Math.floor(rawQueueLimitJobs) : 15000;
     let available = queueLimitJobs === 0 ? Number.POSITIVE_INFINITY : Math.max(0, queueLimitJobs - currentJobCount);
     const admittedPaths = [];
     const deferredPaths = [];

tests/automation-control.test.js

@@ -49,6 +49,16 @@ test('automation settings normalize invalid limits intervals and pause timestamp
   });
 });
 
+test('automation settings allow only numeric and trimmed string zero to disable the queue limit', () => {
+  const invalidLimits = [null, '', '   ', false, true, {}, undefined, NaN, Number.POSITIVE_INFINITY, Number.NEGATIVE_INFINITY, '0.0', '00', '+0', '-0'];
+  assert.deepEqual(
+    invalidLimits.map((queueLimitJobs) => normalizeAutomationSettings({ queueLimitJobs }).queueLimitJobs),
+    invalidLimits.map(() => 15000)
+  );
+  assert.equal(normalizeAutomationSettings({ queueLimitJobs: 0 }).queueLimitJobs, 0);
+  assert.equal(normalizeAutomationSettings({ queueLimitJobs: ' 0 ' }).queueLimitJobs, 0);
+});
+
 test('capacity counts only executable and running queue jobs', () => {
   const statuses = ['preview', 'queued', 'getting-server', 'uploading', 'retrying', 'done', 'error', 'aborted', 'skipped'];
   assert.equal(countAutomaticQueueJobs(statuses.map((status, index) => ({ id: String(index), status }))), 5);
@@ -111,6 +121,31 @@ test('admission tolerates malformed candidates and numeric inputs', () => {
   });
 });
 
+test('admission allows only numeric and trimmed string zero to disable the queue limit', () => {
+  const invalidLimits = [null, '', '   ', false, true, {}, undefined, NaN, Number.POSITIVE_INFINITY, Number.NEGATIVE_INFINITY, '0.0', '00', '+0', '-0'];
+  const candidate = { path: 'large.mkv', mtimeMs: 1, eligibleJobCount: 16000 };
+  assert.deepEqual(
+    invalidLimits.map((queueLimitJobs) => planAtomicAdmissions({ candidates: [candidate], queueLimitJobs })),
+    invalidLimits.map(() => ({
+      admittedPaths: [],
+      deferredPaths: ['large.mkv'],
+      currentJobCount: 0,
+      plannedJobs: 0,
+      availableSlots: 15000
+    }))
+  );
+  assert.deepEqual(
+    [0, ' 0 '].map((queueLimitJobs) => planAtomicAdmissions({ candidates: [candidate], queueLimitJobs })),
+    [0, ' 0 '].map(() => ({
+      admittedPaths: ['large.mkv'],
+      deferredPaths: [],
+      currentJobCount: 0,
+      plannedJobs: 16000,
+      availableSlots: null
+    }))
+  );
+});
+
 test('daily telemetry resets atomically on the local calendar day boundary', () => {
   const before = { dateKey: '2026-08-25', detected: 8, queued: 4, skipped: 2, deferred: 1 };
   const now = new Date(2026, 7, 26, 0, 0, 1).getTime();