fix(chat): add saved AI defaults and harden suggestions

.memory/knowledge/domain/ai-configuration.md

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+# AI Configuration Domain
+
+## WS1 Configuration Infrastructure
+
+### WS1-F1: Instance-level env vars and key fallback
+- `settings.py`: `VOYAGE_AI_PROVIDER`, `VOYAGE_AI_MODEL`, `VOYAGE_AI_API_KEY`
+- `get_llm_api_key(user, provider)` falls back to instance key only when provider matches `VOYAGE_AI_PROVIDER`
+- Fallback chain: user key -> matching-provider instance key -> error
+- See [tech-stack.md](../tech-stack.md#server-side-env-vars-from-settingspy), [decisions.md](../../decisions.md#ws1-configuration-infrastructure-backend-review)
+
+### WS1-F2: UserAISettings model
+- `integrations/models.py`: `UserAISettings` (OneToOneField to user) with `preferred_provider` and `preferred_model`
+- Endpoint: `/api/integrations/ai-settings/` (upsert pattern)
+- Migration: `0008_useraisettings.py`
+
+### WS1-F3: Provider catalog enhancement
+- `get_provider_catalog(user=None)` adds `instance_configured` and `user_configured` booleans
+- User API keys prefetched once per request (no N+1)
+- `ChatProviderCatalogEntry` TypeScript type updated with both fields
+
+### Frontend Provider Selection (Fixed)
+- No longer hardcodes `selectedProvider = 'openai'`; auto-selects first usable provider
+- Filtered to configured+usable entries only (`available_for_chat && (user_configured || instance_configured)`)
+- Warning alert + Settings link when no providers configured
+- Model selection uses dropdown from `GET /api/chat/providers/{provider}/models/`
+
+## Known Frontend Gaps
+
+### Root Cause of User-Facing LLM Errors
+Three compounding issues (all resolved):
+1. ~~Hardcoded `'openai'` default~~ (fixed: auto-selects first usable)
+2. ~~No provider status feedback~~ (fixed: catalog fields consumed)
+3. ~~`UserAISettings.preferred_provider` never loaded~~ (fixed: Settings UI saves/loads DB defaults; chat initializes from saved prefs)
+4. `FIELD_ENCRYPTION_KEY` not set disables key storage (env-dependent)
+5. ~~TypeScript type missing fields~~ (fixed)
+
+## Key Edit Reference Points
+| Feature | File | Location |
+|---|---|---|
+| AI env vars | `backend/server/main/settings.py` | after `FIELD_ENCRYPTION_KEY` |
+| Fallback key | `backend/server/chat/llm_client.py` | `get_llm_api_key()` |
+| UserAISettings model | `backend/server/integrations/models.py` | after UserAPIKey |
+| Catalog user flags | `backend/server/chat/llm_client.py` | `get_provider_catalog()` |
+| Provider view | `backend/server/chat/views/__init__.py` | `ChatProviderCatalogViewSet` |

.memory/knowledge/domain/collections-and-sharing.md

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+# Collections & Sharing Domain
+
+## Collection Sharing Architecture
+
+### Data Model
+- `Collection.shared_with` - `ManyToManyField(User, related_name='shared_with', blank=True)` - the primary access grant
+- `CollectionInvite` - staging table for pending invites: `(collection FK, invited_user FK, unique_together)`; prevents self-invite and double-invite
+- Both models in `backend/server/adventures/models.py`
+
+### Access Flow (Invite -> Accept -> Membership)
+1. Owner calls `POST /api/collections/{id}/share/{uuid}/` -> creates `CollectionInvite`
+2. Invited user sees pending invites via `GET /api/collections/invites/`
+3. Invited user calls `POST /api/collections/{id}/accept-invite/` -> adds to `shared_with`, deletes invite
+4. Owner revokes: `POST /api/collections/{id}/revoke-invite/{uuid}/`
+5. User declines: `POST /api/collections/{id}/decline-invite/`
+6. Owner removes: `POST /api/collections/{id}/unshare/{uuid}/` - removes user's locations from collection
+7. User self-removes: `POST /api/collections/{id}/leave/` - removes their locations
+
+### Permission Classes
+- `CollectionShared` - full access for owner and `shared_with` members; invite actions for invitees; anonymous read for `is_public`
+- `IsOwnerOrSharedWithFullAccess` - child-object viewsets; traverses `obj.collections`/`obj.collection` to check `shared_with`
+- `ContentImagePermission` - delegates to `IsOwnerOrSharedWithFullAccess` on `content_object`
+
+### Key Design Constraints
+- No role differentiation - all shared users have same write access
+- On unshare/leave, departing user's locations are removed from collection (not deleted)
+- `duplicate` action creates a private copy with no `shared_with` transfer
+
+## Itinerary Architecture
+
+### Primary Component
+`CollectionItineraryPlanner.svelte` (~3818 lines) - monolith rendering the entire itinerary view and all modals.
+
+### The "Add" Button
+DaisyUI dropdown at bottom of each day card with "Link existing item" and "Create new" submenu (Location, Lodging, Transportation, Note, Checklist).
+
+### Day Suggestions Modal (WS3)
+- Component: `ItinerarySuggestionModal.svelte`
+- Props: `collection`, `user`, `targetDate`, `displayDate`
+- Events: `close`, `addItem { type: 'location', itemId, updateDate }`
+- 3-step UX: category selection -> filters -> results from `POST /api/chat/suggestions/day/`
+
+## User Recommendation Preference Profile
+Backend-only feature: model, API, and system-prompt integration exist, but **no frontend UI** built yet.
+
+### Auto-learned preference updates
+- `backend/server/integrations/utils/auto_profile.py` derives profile from user history
+- Fields: `interests` (from activities + locations), `trip_style` (from lodging), `notes` (frequently visited regions)
+- `ChatViewSet.send_message()` invokes `update_auto_preference_profile(request.user)` at method start
+
+### Model
+`UserRecommendationPreferenceProfile` (OneToOne -> `CustomUser`): `cuisines`, `interests` (JSONField), `trip_style`, `notes`, timestamps.
+
+### System Prompt Integration
+- Single-user: labeled as auto-inferred with structured markdown section
+- Shared collections: `get_aggregated_preferences(collection)` appends per-participant preferences
+- Missing profiles skipped gracefully
+
+### Frontend Gap
+- No settings tab for manual preference editing
+- TypeScript type available as `UserRecommendationPreferenceProfile` in `src/lib/types.ts`
+- See [Plan: AI travel agent redesign](../../plans/ai-travel-agent-redesign.md#ws2-user-preference-learning)