diff --git a/CHANGELOG.md b/CHANGELOG.md
index 87b76ad4..a22e096b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 ### Fixed
 
 - A failed FTS index build is logged at `WARNING` instead of `DEBUG`, so silent full-text search degradation is visible.
+- Ingester worker ids are now globally unique (`{pid}-{uuid}-{n}`) instead of `worker-{n}`, so the `claimed_by` guards on job completion/reschedule/release distinguish workers across processes sharing one Postgres queue.
 
 ### Changed
 
diff --git a/haiku_rag_slim/haiku/rag/ingester/workers/pool.py b/haiku_rag_slim/haiku/rag/ingester/workers/pool.py
index 464be50e..2be52df4 100644
--- a/haiku_rag_slim/haiku/rag/ingester/workers/pool.py
+++ b/haiku_rag_slim/haiku/rag/ingester/workers/pool.py
@@ -1,7 +1,9 @@
 import asyncio
 import logging
+import os
 import time
 from typing import TYPE_CHECKING
+from uuid import uuid4
 
 from haiku.rag.config import CircuitBreakerConfig
 from haiku.rag.ingester.exceptions import PermanentError, TransientError
@@ -59,12 +61,20 @@ class WorkerPool:
         self._metadata_providers: dict[str, MetadataProvider] = (
             dict(metadata_providers) if metadata_providers else {}
         )
+        # Globally-unique so claimed_by distinguishes this pool's workers from
+        # those of any other process sharing the queue; the claimed_by guards on
+        # mark_succeeded/reschedule/release rely on it. The uuid guarantees
+        # uniqueness; the pid just makes claimed_by readable in logs/dashboard.
+        self._instance = f"{os.getpid()}-{uuid4().hex[:8]}"
         self._stop = asyncio.Event()
         self._workers: list[asyncio.Task] = []
         self._reaper: asyncio.Task | None = None
         self._pending_releases: set[asyncio.Task] = set()
         self._breakers: dict[str, CircuitBreaker] = {}
 
+    def _worker_id(self, i: int) -> str:
+        return f"{self._instance}-{i}"
+
     @property
     def live_workers(self) -> int:
         """Worker tasks that are still running. Equal to worker_count under
@@ -106,7 +116,9 @@ class WorkerPool:
         if reset:
             logger.info("Boot-reaped %d stale claim(s) from previous process", reset)
         for i in range(self._worker_count):
-            self._workers.append(asyncio.create_task(self._worker_loop(f"worker-{i}")))
+            self._workers.append(
+                asyncio.create_task(self._worker_loop(self._worker_id(i)))
+            )
         self._reaper = asyncio.create_task(self._reaper_loop())
 
     async def stop(self) -> None:
diff --git a/tests/ingester/test_workers.py b/tests/ingester/test_workers.py
index f13f826e..207e1cb5 100644
--- a/tests/ingester/test_workers.py
+++ b/tests/ingester/test_workers.py
@@ -31,6 +31,36 @@ def _pool(client, jobs, sync, **kwargs) -> WorkerPool:
     )
 
 
+# --- worker identity ---
+
+
+@pytest.mark.asyncio
+async def test_worker_ids_are_unique_across_pools(client, jobs, sync):
+    """Two pools built with default construction must not share worker ids;
+    otherwise a stale worker from one pool can satisfy the claimed_by guard of
+    a job re-claimed by another pool and clobber its result."""
+    pool_a = _pool(client, jobs, sync)
+    pool_b = _pool(client, jobs, sync)
+    worker_a = pool_a._worker_id(0)
+    worker_b = pool_b._worker_id(0)
+    assert worker_a != worker_b
+
+    job = await jobs.enqueue("src", "u", JobOp.UPSERT)
+    assert job is not None
+
+    claimed = await jobs.claim_next(worker_a)
+    assert claimed is not None
+    # Reaper resets the claim; pool B re-claims and finishes first.
+    await jobs.reap_stale(claim_timeout_seconds=0)
+    reclaimed = await jobs.claim_next(worker_b)
+    assert reclaimed is not None and reclaimed.id == job.id
+    assert await jobs.mark_succeeded(reclaimed.id, worker_b) is True
+
+    # Pool A's slow worker finishes later: with unique ids this is a no-op, so
+    # pool B's success is not clobbered.
+    assert await jobs.mark_succeeded(job.id, worker_a) is False
+
+
 # --- event-driven wakeup ---