fix: gate retries by error category with backoff

Co-authored-by: Copilot App <[email protected]>

tests/services/test_workflows_reliability.py

@@ -2,6 +2,8 @@
 
 import asyncio
 import time
+from datetime import UTC
+from datetime import datetime
 from pathlib import Path
 from uuid import uuid4
 
@@ -20,6 +22,7 @@ from transcription.db.models import Source
 from transcription.providers.base import TranscriptionResult
 from transcription.services import ServiceBundle
 from transcription.services import workflows as workflows_module
+from transcription.services.workflows import advance_job
 from transcription.services.workflows import process_queued_job
 
 
@@ -366,3 +369,63 @@ class TestWorkflowReliability:
         result = await task
         assert result is not None
         assert result.status == JobStatus.TRANSCRIBED
+
+    @pytest.mark.asyncio
+    async def test_failed_job_with_validation_category_is_not_requeued(self, default_session_factory):
+        services = ServiceBundle.from_session_factory(default_session_factory)
+        async with services.jobs._session_scope() as session:
+            document = Document(id=uuid4(), name="validation-failure-doc")
+            session.add(document)
+            await session.flush()
+
+            source = Source(
+                document_id=document.id,
+                page_number=1,
+                upload_name="validation.jpg",
+                filename="validation.jpg",
+                file_path=str(Path("tests/fixtures/images/real/Book Two - page 02.jpg")),
+                file_hash="9" * 64,
+                file_size_bytes=1,
+            )
+            session.add(source)
+            await session.flush()
+
+            job = Job(document_id=document.id, status=JobStatus.FAILED, retry_count=0)
+            session.add(job)
+            await session.flush()
+
+            job_source = JobSource(job_id=job.id, source_id=source.id, status=JobSourceStatus.FAILED)
+            session.add(job_source)
+            await session.flush()
+
+            now = datetime.now(UTC)
+            session.add(
+                ExecutionAttempt(
+                    job_source_id=job_source.id,
+                    job_id=job.id,
+                    source_id=source.id,
+                    attempt_number=1,
+                    status=JobSourceStatus.FAILED,
+                    provider="fixture",
+                    started_at=now,
+                    finished_at=now,
+                    duration_ms=0,
+                    error_category="validation_error",
+                    error_detail="invalid payload",
+                )
+            )
+            await session.commit()
+            failed_job = await services.jobs.read_job(job_id=job.id, session=session)
+
+        result = await advance_job(
+            failed_job,
+            services=services,
+            settings=Settings(openrouter_api_key="test-key", worker_max_retries=1),
+        )
+
+        assert result is None
+        async with services.jobs._session_scope() as session:
+            persisted = await session.get(Job, failed_job.id)
+            assert persisted is not None
+            assert persisted.status == JobStatus.FAILED
+            assert persisted.retry_count == 0