enhancement(epg): Performance improvements and API enhancements for EPG refreshes.

- Updated EPG import logic to reject dummy sources without loading the large `programme_index`, optimizing memory usage during API calls.

CHANGELOG.md

@@ -7,10 +7,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- **Channel list with nested streams loads faster.** `GET /api/channels/channels/?include_streams=true` (Channels UI and single-channel fetch) now builds nested stream payloads from the prefetched `channelstream_set` instead of issuing one extra streams M2M query per channel.
+
 ### Fixed
 
 - **M3U refresh recovers DB connections and account status after failures.** Celery workers now call `close_old_connections()` before and after every task; `refresh_single_m3u_account` also resets its DB connection at task start and retries account loads once after a connection reset (avoids opaque `list index out of range` errors from poisoned worker connections). Accounts leave `fetching`/`parsing` for a terminal `error` or `success` state when refresh aborts. Error-path status updates use `QuerySet.update()` on a clean connection instead of `save()` on a connection that may already be INTRANS after `refresh_m3u_groups` or batch ORM failures. Failed group downloads now set `error` instead of returning silently. Refresh start replaces stale `last_message` text. `refresh_account_profiles` releases DB connections after each profile failure. (Fixes #1338)
 - **M3U `custom_properties` JSON normalization.** Legacy rows and some API writes could store a JSON-encoded string instead of an object in `custom_properties`, causing refresh, profile sync, and auto-sync to fail with `'str' object has no attribute 'get'`. M3U account, profile, and group-relation models normalize on `save()`; group settings bulk writes and read/merge paths use shared helpers in `core.utils` without re-parsing dict values.
+- **`POST /api/epg/import/` no longer loads `programme_index`.** The dummy-source guard uses a narrow existence query instead of `objects.get()`, so import triggers avoid pulling the multi-MB byte-offset index into the uWSGI worker. Request/response shape is unchanged for the UI, plugins, and external importers.
 - **XC live playback URL building now normalizes account server URLs.** On-demand live URLs (introduced for Server Group profile rotation in 0.27.0) rebuild `/live/{user}/{pass}/{stream_id}.ts` from current credentials instead of reusing the synced `stream.url`. That path now runs `normalize_server_url()` so pasted API URLs (e.g. `/player_api.php` with query params) are stripped while sub-paths like `/server1` are preserved. `get_transformed_credentials()` normalizes the base URL at the source; VOD movie and episode relations use the same helper instead of constructing a throwaway `XCClient` (which also avoided per-request HTTP session setup). (Fixes #1363)
 - **Live proxy now releases geventpool DB connections on more paths.** `stream_ts()` calls `close_old_connections()` before `StreamingHttpResponse` so clients waiting on channel init do not keep a pool slot while the generator polls Redis. `generate_stream_url()`, `get_stream_info_for_switch()`, `get_alternate_streams()`, and `get_connections_left()` release in `finally` blocks after ORM work on stream-manager failover paths that run outside Django's request cycle. TS client disconnect cleanup matches fMP4, and `ChannelService` metadata helpers release after their ORM lookups.
 

apps/epg/api_views.py

@@ -1119,18 +1119,24 @@ class EPGImportAPIView(APIView):
         epg_id = request.data.get("id", None)
         force = bool(request.data.get("force", False))
 
-        # Check if this is a dummy EPG source
-        try:
+        # Reject dummy sources without loading programme_index (multi-MB JSON).
+        if epg_id is not None:
             from .models import EPGSource
-            epg_source = EPGSource.objects.get(id=epg_id)
-            if epg_source.source_type == 'dummy':
-                logger.info(f"EPGImportAPIView: Skipping refresh for dummy EPG source {epg_id}")
+
+            if EPGSource.objects.filter(
+                id=epg_id, source_type="dummy"
+            ).exists():
+                logger.info(
+                    "EPGImportAPIView: Skipping refresh for dummy EPG source %s",
+                    epg_id,
+                )
                 return Response(
-                    {"success": False, "message": "Dummy EPG sources do not require refreshing."},
+                    {
+                        "success": False,
+                        "message": "Dummy EPG sources do not require refreshing.",
+                    },
                     status=status.HTTP_400_BAD_REQUEST,
                 )
-        except EPGSource.DoesNotExist:
-            pass  # Let the task handle the missing source
 
         refresh_epg_data.delay(epg_id, force=force)  # Trigger Celery task
         logger.info("EPGImportAPIView: Task dispatched to refresh EPG data.")

apps/epg/tests/test_epg_import_api.py

@@ -0,0 +1,95 @@
+from unittest.mock import patch
+
+from django.contrib.auth import get_user_model
+from django.db import connection
+from django.test.utils import CaptureQueriesContext
+from django.test import TestCase
+from rest_framework import status
+from rest_framework.test import APIClient
+
+from apps.epg.models import EPGSource
+
+User = get_user_model()
+
+IMPORT_URL = "/api/epg/import/"
+
+
+class EPGImportAPITests(TestCase):
+    def setUp(self):
+        self.user = User.objects.create_user(
+            username="epg_import_admin", password="testpass123"
+        )
+        self.user.user_level = 10
+        self.user.save()
+        self.client = APIClient()
+        self.client.force_authenticate(user=self.user)
+
+    @patch("apps.epg.api_views.refresh_epg_data.delay")
+    def test_import_dummy_source_rejected_without_dispatch(self, mock_delay):
+        source = EPGSource.objects.create(
+            name="Dummy EPG",
+            source_type="dummy",
+        )
+
+        response = self.client.post(
+            IMPORT_URL, {"id": source.id}, format="json"
+        )
+
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+        self.assertFalse(response.data["success"])
+        mock_delay.assert_not_called()
+
+    @patch("apps.epg.api_views.refresh_epg_data.delay")
+    def test_import_xmltv_dispatches_without_loading_programme_index(
+        self, mock_delay
+    ):
+        source = EPGSource.objects.create(
+            name="Large Index XMLTV",
+            source_type="xmltv",
+            url="http://example.com/epg.xml",
+            programme_index={
+                "channels": {f"ch.{i}": {"offsets": [0, 100]} for i in range(200)},
+                "interleaved_channels": [],
+            },
+        )
+        mock_delay.reset_mock()
+
+        with CaptureQueriesContext(connection) as ctx:
+            response = self.client.post(
+                IMPORT_URL, {"id": source.id}, format="json"
+            )
+
+        self.assertEqual(response.status_code, status.HTTP_202_ACCEPTED)
+        self.assertTrue(response.data["success"])
+        mock_delay.assert_called_once_with(source.id, force=False)
+        for query in ctx.captured_queries:
+            self.assertNotIn(
+                "programme_index",
+                query["sql"].lower(),
+                "import trigger should not read programme_index",
+            )
+
+    @patch("apps.epg.api_views.refresh_epg_data.delay")
+    def test_import_missing_source_still_dispatches(self, mock_delay):
+        response = self.client.post(IMPORT_URL, {"id": 99999}, format="json")
+
+        self.assertEqual(response.status_code, status.HTTP_202_ACCEPTED)
+        mock_delay.assert_called_once_with(99999, force=False)
+
+    @patch("apps.epg.api_views.refresh_epg_data.delay")
+    def test_import_honours_force_flag(self, mock_delay):
+        source = EPGSource.objects.create(
+            name="Force XMLTV",
+            source_type="xmltv",
+            url="http://example.com/epg.xml",
+        )
+        mock_delay.reset_mock()
+
+        response = self.client.post(
+            IMPORT_URL,
+            {"id": source.id, "force": True},
+            format="json",
+        )
+
+        self.assertEqual(response.status_code, status.HTTP_202_ACCEPTED)
+        mock_delay.assert_called_once_with(source.id, force=True)