diff --git a/ingestify/__init__.py b/ingestify/__init__.py
index 32c740b..25c2755 100644
--- a/ingestify/__init__.py
+++ b/ingestify/__init__.py
@@ -8,6 +8,7 @@
     from .infra import retrieve_http
     from .source_base import Source, DatasetResource
     from .domain.models.resources.batch_loader import BatchLoader
+    from .exceptions import StopProcessing
     from .main import debug_source
 
 __version__ = "0.15.1"
diff --git a/ingestify/domain/models/ingestion/ingestion_job.py b/ingestify/domain/models/ingestion/ingestion_job.py
index 0dca1b0..7704eaa 100644
--- a/ingestify/domain/models/ingestion/ingestion_job.py
+++ b/ingestify/domain/models/ingestion/ingestion_job.py
@@ -26,7 +26,7 @@
 from ingestify.domain.models.resources.batch_loader import BatchLoader
 from ingestify.domain.models.dataset.dataset import DatasetLastModifiedAtMap
 from ingestify.domain.models.task.task_summary import TaskSummary
-from ingestify.exceptions import SaveError, IngestifyError
+from ingestify.exceptions import SaveError, IngestifyError, StopProcessing
 from ingestify.utils import TaskExecutor, chunker
 
 logger = logging.getLogger(__name__)
@@ -529,7 +529,16 @@ def execute(
                     )
                     logger.info(f"Running {len(task_set)} tasks")
 
-                    results = task_executor.run(run_task, task_set)
+                    try:
+                        results = task_executor.run(run_task, task_set)
+                    except StopProcessing:
+                        logger.info(
+                            "StopProcessing raised — saving partial results "
+                            "and stopping"
+                        )
+                        ingestion_job_summary.set_finished()
+                        yield ingestion_job_summary
+                        raise
 
                     # BatchTasks return a list of TaskSummary; flatten.
                     task_summaries = []
diff --git a/ingestify/exceptions.py b/ingestify/exceptions.py
index fca6d8b..cd311a9 100644
--- a/ingestify/exceptions.py
+++ b/ingestify/exceptions.py
@@ -12,3 +12,17 @@ class DuplicateFile(IngestifyError):
 
 class SaveError(IngestifyError):
     pass
+
+
+class StopProcessing(IngestifyError):
+    """Raised by a source or loader to signal that processing should stop
+    gracefully. Successfully processed datasets are preserved; the current
+    task and all remaining tasks are skipped.
+
+    Use this for recoverable situations like API quota exhaustion where
+    retrying later will succeed.
+
+    Exit code: 2 (distinct from 0=success and 1=error).
+    """
+
+    exit_code = 2
diff --git a/ingestify/tests/test_stop_processing.py b/ingestify/tests/test_stop_processing.py
new file mode 100644
index 0000000..8837e05
--- /dev/null
+++ b/ingestify/tests/test_stop_processing.py
@@ -0,0 +1,105 @@
+"""Tests for StopProcessing exception."""
+from unittest.mock import patch
+
+import pytest
+
+from ingestify import Source, DatasetResource
+from ingestify.domain import DataSpecVersionCollection, DraftFile, Selector
+from ingestify.domain.models.dataset.collection_metadata import (
+    DatasetCollectionMetadata,
+)
+from ingestify.domain.models.fetch_policy import FetchPolicy
+from ingestify.domain.models.ingestion.ingestion_plan import IngestionPlan
+from ingestify.exceptions import StopProcessing
+from ingestify.utils import utcnow
+
+
+def good_loader(file_resource, current_file, **kwargs):
+    return DraftFile.from_input("data", data_feed_key="f1")
+
+
+def stopping_loader(file_resource, current_file, **kwargs):
+    raise StopProcessing("API quota exhausted")
+
+
+class SourceWithStopProcessing(Source):
+    """Source that yields 5 datasets. The 3rd one raises StopProcessing."""
+
+    provider = "test_provider"
+
+    def find_datasets(
+        self, dataset_type, data_spec_versions, dataset_collection_metadata, **kwargs
+    ):
+        for i in range(5):
+            loader = stopping_loader if i == 2 else good_loader
+            r = DatasetResource(
+                dataset_resource_id={"item_id": i},
+                provider=self.provider,
+                dataset_type="test",
+                name=f"item-{i}",
+            )
+            r.add_file(
+                last_modified=utcnow(),
+                data_feed_key="f1",
+                data_spec_version="v1",
+                file_loader=loader,
+            )
+            yield r
+
+
+def _setup(engine, source):
+    dsv = DataSpecVersionCollection.from_dict({"default": {"v1"}})
+    engine.add_ingestion_plan(
+        IngestionPlan(
+            source=source,
+            fetch_policy=FetchPolicy(),
+            dataset_type="test",
+            selectors=[Selector.build({}, data_spec_versions=dsv)],
+            data_spec_versions=dsv,
+        )
+    )
+
+
+def test_stop_processing_has_exit_code():
+    assert StopProcessing.exit_code == 2
+
+
+def test_stop_processing_propagates(engine):
+    """StopProcessing raised by a loader propagates out of engine.run()."""
+    _setup(engine, SourceWithStopProcessing("s"))
+
+    with pytest.raises(StopProcessing, match="quota exhausted"):
+        engine.run()
+
+
+def test_stop_processing_preserves_completed_datasets(engine):
+    """Datasets processed before StopProcessing are saved."""
+    _setup(engine, SourceWithStopProcessing("s"))
+
+    try:
+        engine.run()
+    except StopProcessing:
+        pass
+
+    datasets = list(
+        engine.store.get_dataset_collection(
+            provider="test_provider",
+            dataset_type="test",
+        )
+    )
+    assert len(datasets) == 2
+
+
+def test_stop_processing_saves_ingestion_job_summary(engine):
+    """IngestionJobSummary is saved even when StopProcessing occurs."""
+    _setup(engine, SourceWithStopProcessing("s"))
+
+    with patch.object(engine.store, "save_ingestion_job_summary") as mock_save:
+        try:
+            engine.run()
+        except StopProcessing:
+            pass
+
+        assert (
+            mock_save.call_count >= 1
+        ), "save_ingestion_job_summary should be called even on StopProcessing"