diff --git a/src/commands/jobs.ts b/src/commands/jobs.ts
index de60cba2a..604f4510b 100644
--- a/src/commands/jobs.ts
+++ b/src/commands/jobs.ts
@@ -233,7 +233,7 @@ USAGE
   gbrain jobs get <id>
   gbrain jobs cancel <id>
   gbrain jobs retry <id>
-  gbrain jobs prune [--older-than 30d]
+  gbrain jobs prune [--older-than 30d] [--dry-run]
   gbrain jobs delete <id>
   gbrain jobs stats
   gbrain jobs smoke
@@ -633,8 +633,15 @@ HANDLER TYPES (built in)
       try { await queue.ensureSchema(); }
       catch (e) { console.error(e instanceof Error ? e.message : String(e)); process.exit(1); }
 
-      const count = await queue.prune({ olderThan: new Date(Date.now() - days * 86400000) });
-      console.log(`Pruned ${count} jobs older than ${days} days.`);
+      // #2712: --dry-run previews the count without deleting. It used to be
+      // silently ignored (the destructive default ran anyway).
+      const dryRun = hasFlag(args, '--dry-run');
+      const count = await queue.prune({ olderThan: new Date(Date.now() - days * 86400000), dryRun });
+      if (dryRun) {
+        console.log(`[dry-run] Would prune ${count} jobs older than ${days} days. Nothing deleted.`);
+      } else {
+        console.log(`Pruned ${count} jobs older than ${days} days.`);
+      }
       break;
     }
 
diff --git a/src/core/minions/queue.ts b/src/core/minions/queue.ts
index 0d0780fdb..1c8334330 100644
--- a/src/core/minions/queue.ts
+++ b/src/core/minions/queue.ts
@@ -534,10 +534,21 @@ export class MinionQueue {
   }
 
   /** Prune old jobs in terminal statuses. Returns count of deleted rows. */
-  async prune(opts?: { olderThan?: Date; status?: MinionJobStatus[] }): Promise<number> {
+  async prune(opts?: { olderThan?: Date; status?: MinionJobStatus[]; dryRun?: boolean }): Promise<number> {
     const statuses = opts?.status ?? ['completed', 'dead', 'cancelled'];
     const olderThan = opts?.olderThan ?? new Date(Date.now() - 30 * 86400000);
 
+    // #2712: dryRun counts the would-be-pruned rows without deleting.
+    // Silent-ignoring a safety flag on a delete path is data loss.
+    if (opts?.dryRun) {
+      const rows = await this.engine.executeRaw<{ count: string }>(
+        `SELECT count(*)::text as count FROM minion_jobs
+         WHERE status = ANY($1) AND updated_at < $2`,
+        [statuses, olderThan.toISOString()]
+      );
+      return parseInt(rows[0]?.count ?? '0', 10);
+    }
+
     const rows = await this.engine.executeRaw<{ count: string }>(
       `WITH pruned AS (
          DELETE FROM minion_jobs
diff --git a/test/minions.test.ts b/test/minions.test.ts
index 90148361e..a76a56ed9 100644
--- a/test/minions.test.ts
+++ b/test/minions.test.ts
@@ -709,6 +709,26 @@ describe('MinionQueue: Prune', () => {
     const count = await queue.prune({ olderThan: new Date(Date.now() + 86400000) }); // future date = prune everything old enough
     expect(count).toBe(1); // only the cancelled one
   });
+
+  // #2712: --dry-run used to be silently ignored — the destructive default
+  // ran and deleted rows while the operator believed they were previewing.
+  test('dryRun counts prunable jobs without deleting', async () => {
+    const job1 = await queue.add('sync', {});
+    await queue.cancelJob(job1.id); // terminal → prunable
+
+    const wouldPrune = await queue.prune({ olderThan: new Date(Date.now() + 86400000), dryRun: true });
+    expect(wouldPrune).toBe(1);
+
+    // The row must still exist after a dry run.
+    const stillThere = await queue.getJob(job1.id);
+    expect(stillThere).not.toBeNull();
+    expect(stillThere!.status).toBe('cancelled');
+
+    // A real prune afterwards actually deletes it.
+    const pruned = await queue.prune({ olderThan: new Date(Date.now() + 86400000) });
+    expect(pruned).toBe(1);
+    expect(await queue.getJob(job1.id)).toBeNull();
+  });
 });
 
 // --- Stats (1 test) ---