v4: 7643 tests passing, 83% raw / 96.9% real coverage (excl __tests__).

12 known failures — all from Agent 3 new unverified tests (mock setup issues):
- 3 dataset_review_routes_extended (DTO field mismatches)
- 1 settings_consolidated (dict key access)
- 1 llm_analysis_service_coverage (rate_limit mock)
- 1 migration_plugin (SessionLocal side_effect exhaustion)
- 1 preview (DB query vs dict key)
- 5 scheduler (datetime timezone + async mock mismatches)

NEW TEST FILES THIS SESSION:
- test_batch_insert_coverage.py — 3 tests
- test_storage_plugin.py — +3 tests
- test_search.py — +2 tests
- test_mapper.py — already 100%
- test_llm_analysis_migration_v1_to_v2.py — 14 tests
- test_llm_async_http.py — +1 test
- test_prompt_builder.py — +1 test
- test_service_datasource.py — +1 test
- test_lang_detect.py — +1 test
- test_scheduler.py — +6 tests
- test_llm_analysis_service_coverage.py — +15 tests
- test_dataset_review_routes_extended.py — +14 tests
- test_settings_consolidated.py — +13 tests

Modules pushed to 100%: _batch_insert, dictionary_entries, service_datasource,
_llm_async_http, prompt_builder, dictionary_crud, _batch_sizer, storage/plugin,
mapper.py

Session: 7194→7643 tests (+449), 80%→83% raw (+3pp), 93.4%→96.9% real (+3.5pp).
Remaining: 12 failures to fix + ~300 statements to reach 98% real coverage.

backend/tests/plugins/translate/test_executor.py

@@ -418,4 +418,104 @@ class TestDelegationWrappers:
             MockLLM._parse_llm_response.return_value = {"0": {"fr": "test"}}
             result = TranslationExecutor._parse_llm_response('{"fr": "test"}', 1, ["fr"])
             assert result == {"0": {"fr": "test"}}
+
+
+class TestPrepareBatches:
+    """Verify _prepare_batches edge cases."""
+
+    def test_target_languages_not_list(self, db_session):
+        """Edge: target_languages is a single string, not list -> wrapped into list."""
+        config = MagicMock()
+        executor = TranslationExecutor(db_session, config)
+        job = MagicMock(spec=TranslationJob)
+        job.target_languages = "fr"  # single string, not list
+        job.target_dialect = "fr"
+
+        with patch.object(executor, '_auto_size_batches', return_value=[]):
+            tls, batches = executor._prepare_batches(job, [], "run-1")
+
+        assert tls == ["fr"]
+        assert batches == []
+
+    def test_target_languages_none_uses_dialect(self, db_session):
+        """Edge: target_languages is None, falls back to target_dialect."""
+        config = MagicMock()
+        executor = TranslationExecutor(db_session, config)
+        job = MagicMock(spec=TranslationJob)
+        job.target_languages = None
+        job.target_dialect = "de"
+
+        with patch.object(executor, '_auto_size_batches', return_value=[]):
+            tls, batches = executor._prepare_batches(job, [], "run-1")
+
+        assert tls == ["de"]
+
+
+class TestProcessBatchesEdgeCases:
+    """Verify _process_batches edge cases."""
+
+    @pytest.mark.asyncio
+    async def test_language_stats_update_error_non_fatal(self, db_with_run):
+        """Edge: language stats update fails, processing continues."""
+        session, run_id = db_with_run
+        config = MagicMock()
+        executor = TranslationExecutor(session, config)
+        job = _make_job(session)
+        run = session.query(TranslationRun).filter(TranslationRun.id == run_id).first()
+
+        batches = [
+            [{"row_index": "0", "source_text": "Hello", "source_data": {"table": "t"}}],
+        ]
+        language_stats_map = {"fr": MagicMock()}
+
+        with patch.object(executor, '_process_batch',
+                          new=AsyncMock(return_value={
+                              "successful": 1, "failed": 0, "skipped": 0,
+                              "retries": 0, "cache_hits": 0, "batch_id": "batch-1",
+                          })):
+            with patch.object(executor, '_insert_batch_to_target',
+                              new=AsyncMock(return_value=None)):
+                with patch.object(executor, '_update_language_stats_incremental',
+                                  side_effect=ValueError("Stats update failed")):
+                    # Should not raise — stats failure is non-fatal
+                    result = await executor._process_batches(
+                        run, job, batches, ["fr"], language_stats_map,
+                    )
+                    assert result.status is not None
+
+
+class TestDelegationWrappersExtra:
+    """Additional delegation wrapper tests for uncovered lines."""
+
+    def test_update_language_stats_incremental_delegates(self, db_session):
+        """Verify _update_language_stats_incremental delegates to _run_service."""
+        config = MagicMock()
+        executor = TranslationExecutor(db_session, config)
+        stats_map = {"fr": MagicMock()}
+
+        with patch.object(executor._run_service, '_update_language_stats_incremental') as mock_update:
+            executor._update_language_stats_incremental("run-1", stats_map)
+            mock_update.assert_called_once_with("run-1", stats_map)
+
+    def test_resolve_provider_config_exception(self, db_session):
+        """Edge: LLMProviderService raises, returns safe defaults."""
+        config = MagicMock()
+        executor = TranslationExecutor(db_session, config)
+        job = MagicMock()
+        job.provider_id = "test-provider"
+
+        with patch('src.plugins.translate.executor.LLMProviderService') as MockSvc:
+            mock_instance = MockSvc.return_value
+            mock_instance.get_provider_token_config.side_effect = ValueError("DB error")
+            result = executor._resolve_provider_config(job)
+            assert result == {"model": None, "context_window": None, "max_output_tokens": None}
+
+    def test_resolve_provider_config_exception_no_provider(self, db_session):
+        """Edge: provider_id is None, returns safe defaults directly."""
+        config = MagicMock()
+        executor = TranslationExecutor(db_session, config)
+        job = MagicMock()
+        job.provider_id = None
+        result = executor._resolve_provider_config(job)
+        assert result == {"model": None, "context_window": None, "max_output_tokens": None}
 # #endregion Test.TranslationExecutor