diff --git a/CHANGELOG.md b/CHANGELOG.md
index 91eeb43..c7767ca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,11 @@ new features, modules, protocols, or speculative refactors.
   This prevents a rejected stale revision from starving a subsequent Web or
   automatic Bluetooth request; rejection, generation, ACK, causal, schema,
   and transport contracts are unchanged.
+- Preserved the desktop consumer's known Sleep revision rejection diagnostic
+  through the full-generation worker and classified it as `data_conflict` in
+  Web run state. A synthetic divergent-final-wake regression keeps the true
+  conflict rejected; this reporting fix does not reconcile real Sleep data or
+  turn a rejected generation into a successful exchange.
 
 ## 0.1.6 — 2026-09-25
 
diff --git a/docs/sync_exchange.md b/docs/sync_exchange.md
index 81626e1..17fc89b 100644
--- a/docs/sync_exchange.md
+++ b/docs/sync_exchange.md
@@ -35,6 +35,12 @@ V1 input omits `quantity` and is normalized to one unit. Exact revision replay
 is unchanged; sibling revisions and resurrection after deletion are rejected
 in the generation consumption transaction.
 
+A durable Sleep rejection keeps its exact ACK and does not advance either
+causal tip. The full-generation worker carries the consumer's bounded Sleep
+diagnostic through to the Web run state, where a known concurrent revision is
+reported as `data_conflict` rather than an opaque `internal_error`. This
+classification does not retry, merge, or acknowledge the rejected generation.
+
 This does not change `TRAINLOG_FORMAT_V1`, manifests, ACKs or causal
 ownership.
 
diff --git a/tests/test_sleep_diary_exchange.py b/tests/test_sleep_diary_exchange.py
index c239574..73a1f85 100644
--- a/tests/test_sleep_diary_exchange.py
+++ b/tests/test_sleep_diary_exchange.py
@@ -246,6 +246,48 @@ class SleepExchangeTest(unittest.TestCase):
         with self.assertRaisesRegex(ValueError, "positive"):
             exchange.validate(self.document(invalid))
 
+    def test_contradictory_final_get_up_siblings_remain_unresolved(self):
+        base = "slr_20000000-0000-4000-8000-000000000002"
+        desktop_tip = "slr_40000000-0000-4000-8000-000000000004"
+        android_parent = "slr_50000000-0000-4000-8000-000000000005"
+        android_tip = "slr_60000000-0000-4000-8000-000000000006"
+        self.assertEqual((1, 0), exchange.apply(self.db, self.document(entry(base))))
+
+        desktop = entry(desktop_tip, base)
+        desktop["events"].append({
+            "event_id": "sle_70000000-0000-4000-8000-000000000007",
+            "type": "final_get_up", "start_at": "2026-10-25T06:30:00+01:00",
+            "end_at": None,
+        })
+        self.assertEqual((1, 0), exchange.apply(self.db, self.document(desktop)))
+        before = self.db.execute(
+            "SELECT revision_id,parent_revision_id FROM sleep_diary_revisions "
+            "ORDER BY revision_id"
+        ).fetchall()
+
+        android = entry(android_tip, android_parent)
+        android["ancestry"] = [android_tip, android_parent, base]
+        android["events"][0]["end_at"] = "2026-10-25T06:50:00+01:00"
+        android["events"].append({
+            "event_id": "sle_80000000-0000-4000-8000-000000000008",
+            "type": "final_get_up", "start_at": "2026-10-25T06:50:00+01:00",
+            "end_at": None,
+        })
+        with self.assertRaisesRegex(ValueError, "concurrent sleep diary revision"):
+            exchange.apply(self.db, self.document(android))
+
+        self.assertEqual(before, self.db.execute(
+            "SELECT revision_id,parent_revision_id FROM sleep_diary_revisions "
+            "ORDER BY revision_id"
+        ).fetchall())
+        self.assertEqual(desktop_tip, self.db.execute(
+            "SELECT current_revision_id FROM sleep_diary_entries"
+        ).fetchone()[0])
+        self.assertEqual(1, self.db.execute(
+            "SELECT COUNT(*) FROM sleep_diary_events WHERE revision_id=? "
+            "AND event_type='final_get_up'", (desktop_tip,)
+        ).fetchone()[0])
+
     def test_draft_is_durable_but_not_exported_until_validated(self):
         revision = "slr_20000000-0000-4000-8000-000000000002"
         item = entry(revision)
diff --git a/tests/test_sync_error_classification.py b/tests/test_sync_error_classification.py
index e42dcc9..b7db830 100644
--- a/tests/test_sync_error_classification.py
+++ b/tests/test_sync_error_classification.py
@@ -159,6 +159,12 @@ class SyncErrorClassificationTest(unittest.TestCase):
             sync_orchestrator.failure_code(RuntimeError("revision conflict")),
             "data_conflict",
         )
+        self.assertEqual(
+            sync_orchestrator.failure_code(RuntimeError(
+                "desktop rejected Android generation: concurrent sleep diary revision"
+            )),
+            "data_conflict",
+        )
 
     def test_mtp_outbox_excludes_retained_staging_and_unrelated_files(self):
         with tempfile.TemporaryDirectory() as directory:
diff --git a/tests/test_sync_peer_worker.py b/tests/test_sync_peer_worker.py
index bcbc4fd..e83e6cf 100644
--- a/tests/test_sync_peer_worker.py
+++ b/tests/test_sync_peer_worker.py
@@ -26,6 +26,19 @@ class SyncPeerWorkerTest(unittest.TestCase):
     def tearDown(self):
         self.temporary.cleanup()
 
+    def test_rejected_android_generation_retains_consumer_diagnostic(self):
+        error = worker.rejected_android_generation_error(
+            {"diagnostic": "concurrent sleep diary revision"}
+        )
+        self.assertEqual(
+            str(error),
+            "desktop rejected Android generation: concurrent sleep diary revision",
+        )
+        self.assertEqual(
+            str(worker.rejected_android_generation_error({"diagnostic": ""})),
+            "desktop rejected Android generation",
+        )
+
     def test_drive_adapter_uses_remaining_conversation_deadline(self):
         completed = subprocess.CompletedProcess([], 0, b"", b"")
         with mock.patch.object(worker.subprocess, "run", return_value=completed) as run:
diff --git a/tools/sync_orchestrator.py b/tools/sync_orchestrator.py
index 3669837..4638e95 100644
--- a/tools/sync_orchestrator.py
+++ b/tools/sync_orchestrator.py
@@ -131,7 +131,8 @@ def failure_code(error: BaseException) -> str:
         return "device_unavailable"
     if "capacity exhausted" in diagnostic or "retained generation capacity" in diagnostic:
         return "capacity_exhausted"
-    if "conflict" in diagnostic or "wrong consumer" in diagnostic:
+    if ("conflict" in diagnostic or "wrong consumer" in diagnostic or
+            "concurrent sleep diary revision" in diagnostic):
         return "data_conflict"
     return "internal_error"
 
diff --git a/tools/sync_peer_worker.py b/tools/sync_peer_worker.py
index 3e031a3..3324c2b 100644
--- a/tools/sync_peer_worker.py
+++ b/tools/sync_peer_worker.py
@@ -72,6 +72,15 @@ def emit(run_id: str, phase: str, **values: object) -> None:
     print(json.dumps(value, sort_keys=True, separators=(",", ":")), flush=True)
 
 
+def rejected_android_generation_error(ack: dict) -> RuntimeError:
+    """Keep the durable peer rejection visible without changing its ACK."""
+    # WHY: the browser cannot classify a known causal conflict when the worker
+    # drops the consumer's bounded diagnostic at this process boundary.
+    diagnostic = ack.get("diagnostic", "")
+    detail = f": {diagnostic}" if diagnostic else ""
+    return RuntimeError(f"desktop rejected Android generation{detail}")
+
+
 def bounded(path: Path, limit: int = 65536) -> bytes:
     with path.open("rb") as stream:
         raw = stream.read(limit + 1)
@@ -805,7 +814,7 @@ def main() -> int:
             deadline,
         )
     if ack["result"] != "consumed":
-        raise RuntimeError("desktop rejected Android generation")
+        raise rejected_android_generation_error(ack)
     emit(
         args.run_id,
         "local_import_committed",