feat(ai): implement agent-redesign plan with enhanced AI travel features

Phase 1 - Configuration Infrastructure (WS1):
- Add instance-level AI env vars (VOYAGE_AI_PROVIDER, VOYAGE_AI_MODEL, VOYAGE_AI_API_KEY)
- Implement fallback chain: user key → instance key → error
- Add UserAISettings model for per-user provider/model preferences
- Enhance provider catalog with instance_configured and user_configured flags
- Optimize provider catalog to avoid N+1 queries

Phase 1 - User Preference Learning (WS2):
- Add Travel Preferences tab to Settings page
- Improve preference formatting in system prompt with emoji headers
- Add multi-user preference aggregation for shared collections

Phase 2 - Day-Level Suggestions Modal (WS3):
- Create ItinerarySuggestionModal with 3-step flow (category → filters → results)
- Add AI suggestions button to itinerary Add dropdown
- Support restaurant, activity, event, and lodging categories
- Backend endpoint POST /api/chat/suggestions/day/ with context-aware prompts

Phase 3 - Collection-Level Chat Improvements (WS4):
- Inject collection context (destination, dates) into chat system prompt
- Add quick action buttons for common queries
- Add 'Add to itinerary' button on search_places results
- Update chat UI with travel-themed branding and improved tool result cards

Phase 3 - Web Search Capability (WS5):
- Add web_search agent tool using DuckDuckGo
- Support location_context parameter for biased results
- Handle rate limiting gracefully

Phase 4 - Extensibility Architecture (WS6):
- Implement decorator-based @agent_tool registry
- Convert existing tools to use decorators
- Add GET /api/chat/capabilities/ endpoint for tool discovery
- Refactor execute_tool() to use registry pattern

backend/server/integrations/migrations/0008_useraisettings.py

@@ -0,0 +1,52 @@
+# Generated by Django 5.2.12 on 2026-03-08
+
+import django.db.models.deletion
+import uuid
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("integrations", "0007_userapikey_userrecommendationpreferenceprofile"),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="UserAISettings",
+            fields=[
+                (
+                    "id",
+                    models.UUIDField(
+                        default=uuid.uuid4,
+                        editable=False,
+                        primary_key=True,
+                        serialize=False,
+                    ),
+                ),
+                (
+                    "preferred_provider",
+                    models.CharField(blank=True, max_length=100, null=True),
+                ),
+                (
+                    "preferred_model",
+                    models.CharField(blank=True, max_length=100, null=True),
+                ),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                ("updated_at", models.DateTimeField(auto_now=True)),
+                (
+                    "user",
+                    models.OneToOneField(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="ai_settings",
+                        to=settings.AUTH_USER_MODEL,
+                    ),
+                ),
+            ],
+            options={
+                "verbose_name": "User AI Settings",
+                "verbose_name_plural": "User AI Settings",
+            },
+        ),
+    ]

backend/server/integrations/models.py

@@ -124,3 +124,23 @@ class UserRecommendationPreferenceProfile(models.Model):
     notes = models.TextField(blank=True, null=True)
     created_at = models.DateTimeField(auto_now_add=True)
     updated_at = models.DateTimeField(auto_now=True)
+
+
+class UserAISettings(models.Model):
+    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
+    user = models.OneToOneField(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.CASCADE,
+        related_name="ai_settings",
+    )
+    preferred_provider = models.CharField(max_length=100, blank=True, null=True)
+    preferred_model = models.CharField(max_length=100, blank=True, null=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        verbose_name = "User AI Settings"
+        verbose_name_plural = "User AI Settings"
+
+    def __str__(self):
+        return f"AI Settings for {self.user.username}"

backend/server/integrations/serializers.py

@@ -3,6 +3,7 @@ from django.db import IntegrityError
 from .models import (
     EncryptionConfigurationError,
     ImmichIntegration,
+    UserAISettings,
     UserAPIKey,
     UserRecommendationPreferenceProfile,
 )
@@ -98,3 +99,16 @@ class UserRecommendationPreferenceProfileSerializer(serializers.ModelSerializer)
             "updated_at",
         ]
         read_only_fields = ["id", "created_at", "updated_at"]
+
+
+class UserAISettingsSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = UserAISettings
+        fields = [
+            "id",
+            "preferred_provider",
+            "preferred_model",
+            "created_at",
+            "updated_at",
+        ]
+        read_only_fields = ["id", "created_at", "updated_at"]

backend/server/integrations/urls.py

@@ -6,6 +6,7 @@ from integrations.views import (
     StravaIntegrationView,
     WandererIntegrationViewSet,
     UserAPIKeyViewSet,
+    UserAISettingsViewSet,
     UserRecommendationPreferenceProfileViewSet,
 )
 
@@ -22,6 +23,7 @@ router.register(
     UserRecommendationPreferenceProfileViewSet,
     basename="user-recommendation-preferences",
 )
+router.register(r"ai-settings", UserAISettingsViewSet, basename="user-ai-settings")
 
 # Include the router URLs
 urlpatterns = [

backend/server/integrations/views/__init__.py

@@ -4,3 +4,4 @@ from .strava_view import StravaIntegrationView
 from .wanderer_view import WandererIntegrationViewSet
 from .user_api_key_view import UserAPIKeyViewSet
 from .recommendation_profile_view import UserRecommendationPreferenceProfileViewSet
+from .ai_settings_view import UserAISettingsViewSet

backend/server/integrations/views/ai_settings_view.py

@@ -0,0 +1,39 @@
+from rest_framework import status, viewsets
+from rest_framework.permissions import IsAuthenticated
+from rest_framework.response import Response
+
+from integrations.models import UserAISettings
+from integrations.serializers import UserAISettingsSerializer
+
+
+class UserAISettingsViewSet(viewsets.ModelViewSet):
+    serializer_class = UserAISettingsSerializer
+    permission_classes = [IsAuthenticated]
+
+    def get_queryset(self):
+        return UserAISettings.objects.filter(user=self.request.user)
+
+    def list(self, request, *args, **kwargs):
+        instance = self.get_queryset().first()
+        if not instance:
+            return Response([], status=status.HTTP_200_OK)
+        serializer = self.get_serializer(instance)
+        return Response([serializer.data], status=status.HTTP_200_OK)
+
+    def perform_create(self, serializer):
+        existing = UserAISettings.objects.filter(user=self.request.user).first()
+        if existing:
+            for field, value in serializer.validated_data.items():
+                setattr(existing, field, value)
+            existing.save()
+            self._upserted_instance = existing
+            return
+
+        self._upserted_instance = serializer.save(user=self.request.user)
+
+    def create(self, request, *args, **kwargs):
+        serializer = self.get_serializer(data=request.data)
+        serializer.is_valid(raise_exception=True)
+        self.perform_create(serializer)
+        output = self.get_serializer(self._upserted_instance)
+        return Response(output.data, status=status.HTTP_200_OK)