fix(translate): fix job creation tab navigation and preview validation

- frontend: add  to reload job data on param change after goto
- frontend: set existingJob from createJob response for immediate tabs
- frontend: suppress error toasts for schedule 404 (normal state)
- frontend: conditional ScheduleConfig mount to avoid 'new' job loading
- backend: skip preview check for jobs with direct Superset datasource
- backend: add orthogonal test for datasource+no-preview success case

backend/src/plugins/translate/__tests__/test_orchestrator.py

@@ -191,8 +191,30 @@ class TestTranslationOrchestrator:
         assert run.status == "PENDING"
         assert run.job_id == "job-123"
 
+    # region test_start_run_with_datasource_no_preview_succeeds [TYPE Function]
+    # @PURPOSE: Manual run with Superset datasource succeeds even without accepted preview session.
+    def test_start_run_with_datasource_no_preview_succeeds(
+        self,
+        mock_job: MagicMock,
+    ) -> None:
+        db = MagicMock()
+        config_manager = MagicMock()
+
+        # Mock job query — job HAS a Superset datasource (fixture sets source_datasource_id="42")
+        db.query.return_value.filter.return_value.first.return_value = mock_job
+
+        # No accepted preview session mock — not needed because datasource bypasses preview check.
+        # validate_job_preconditions skips preview query when source_datasource_id is set.
+        # This verifies the gating logic: datasource → no preview required → run proceeds.
+
+        orch = TranslationOrchestrator(db, config_manager, "test-user")
+        run = orch.start_run(job_id="job-123")
+
+        assert run.status == "PENDING"
+        assert run.job_id == "job-123"
+
     # region test_start_run_missing_preview_raises [TYPE Function]
-    # @PURPOSE: Manual run without accepted preview raises ValueError.
+    # @PURPOSE: Manual run without accepted preview raises ValueError when job has no direct datasource.
     def test_start_run_missing_preview_raises(
         self,
         mock_job: MagicMock,
@@ -200,7 +222,9 @@ class TestTranslationOrchestrator:
         db = MagicMock()
         config_manager = MagicMock()
 
-        # Mock job query
+        # Mock job query — job WITHOUT a Superset datasource, so preview is required
+        mock_job.source_datasource_id = None
+        mock_job.environment_id = None
         db.query.return_value.filter.return_value.first.return_value = mock_job
 
         # No accepted preview session

backend/src/plugins/translate/orchestrator_validation.py

@@ -39,19 +39,23 @@ def validate_job_preconditions(
             "Select a translation column before running."
         )
     if not is_scheduled:
-        from ...models.translate import TranslationPreviewSession
-        accepted_session = (
-            db_session.query(TranslationPreviewSession)
-            .filter(
-                TranslationPreviewSession.job_id == job.id,
-                TranslationPreviewSession.status == "APPLIED",
-            )
-            .order_by(TranslationPreviewSession.created_at.desc())
-            .first()
-        )
-        if not accepted_session:
-            raise ValueError(
-                f"Job '{job.id}' has no accepted preview session. "
-                "Run and accept a preview before executing a manual translation run."
+        # Jobs with a direct Superset datasource can fetch rows from Superset directly
+        # (see RunSourceFetcher.fetch_source_rows), so they don't need a preview session.
+        # Only require an accepted preview for jobs without a configured datasource.
+        if not bool(job.source_datasource_id):
+            from ...models.translate import TranslationPreviewSession
+            accepted_session = (
+                db_session.query(TranslationPreviewSession)
+                .filter(
+                    TranslationPreviewSession.job_id == job.id,
+                    TranslationPreviewSession.status == "APPLIED",
+                )
+                .order_by(TranslationPreviewSession.created_at.desc())
+                .first()
             )
+            if not accepted_session:
+                raise ValueError(
+                    f"Job '{job.id}' has no accepted preview session. "
+                    "Run and accept a preview before executing a manual translation run."
+                )
 # #endregion validate_job_preconditions