add tags

Trip-level tags: admins configure available tags in the trip header (inline add/remove pills). The AI can also create new tags via the add_tag tool.
Event tags: selectable in the Add Event modal, shown as colored pills on event cards in the timeline, and on AI suggestion cards.
AI integration: sees available tags in its system prompt, applies them when proposing events, can create new ones with add_tag.
Discord: tags shown as inline code blocks under each event in /trip view.
Colors: auto-assigned from an 8-color palette by tag index, consistent everywhere.

drb-c2-core/app/routers/trips.py

@@ -47,6 +47,26 @@ _TOOLS = [
             },
         },
     },
+    {
+        "type": "function",
+        "function": {
+            "name": "add_tag",
+            "description": (
+                "Add a new tag to the trip's available tag list so it can be used on events. "
+                "Use this when you want to apply a tag that doesn't exist yet."
+            ),
+            "parameters": {
+                "type": "object",
+                "properties": {
+                    "tag": {
+                        "type": "string",
+                        "description": "Short tag label, e.g. 'must-do', 'nightlife', 'food'",
+                    },
+                },
+                "required": ["tag"],
+            },
+        },
+    },
     {
         "type": "function",
         "function": {
@@ -66,6 +86,7 @@ _TOOLS = [
                     "location":   {"type": "string", "description": "Full address or place name"},
                     "maps_link":  {"type": "string", "description": "Google Maps URL"},
                     "notes":      {"type": "string", "description": "Brief tips or reasoning"},
+                    "tags":       {"type": "array", "items": {"type": "string"}, "description": "Tags to apply — must be from the trip's available tags list"},
                 },
                 "required": ["title"],
             },
@@ -133,13 +154,15 @@ def _build_system_prompt(trip: dict, events: list[dict]) -> str:
 
     itinerary = "".join(lines) if lines else "\n  (no events yet)"
     attendees = ", ".join(trip.get("attendees", {}).values()) or "not specified"
+    available_tags = trip.get("available_tags") or []
+    tags_section = f"\nAvailable tags: {', '.join(available_tags)}" if available_tags else ""
 
     return f"""You are a trip planning assistant for the following trip.
 
 Trip: {trip["name"]}
 Destination: {trip["location"]}
 Dates: {trip["start_date"]} to {trip["end_date"]}
-Attendees: {attendees}
+Attendees: {attendees}{tags_section}
 
 Current itinerary:{itinerary}
 
@@ -148,6 +171,7 @@ Guidelines:
 - Format all responses using Markdown: use **bold** for place names and key details, bullet lists for options, and [links](url) for Maps links.
 - When the user mentions places, activities, or asks for suggestions, search for them with search_places before proposing.
 - Use propose_event for each concrete suggestion — one call per event. The user will approve or skip each one.
+- When proposing events, apply relevant tags from the available tags list if any are defined.
 - Be mindful of the existing schedule when assigning times. Avoid obvious conflicts.
 - All proposed dates must fall between {trip["start_date"]} and {trip["end_date"]}.
 - If the user says something like "everyone should be there by 6", factor that into your time proposals.
@@ -183,6 +207,7 @@ async def create_trip(body: TripCreate):
         "start_date": body.start_date,
         "end_date": body.end_date,
         "attendees": {},  # {discord_user_id: discord_username}
+        "available_tags": body.available_tags,
         "created_at": now,
     }
     await fstore.doc_set("trips", trip_id, doc, merge=False)
@@ -199,6 +224,17 @@ async def get_trip(trip_id: str):
     return {**trip, "events": events}
 
 
+@router.put("/{trip_id}/tags")
+async def update_trip_tags(trip_id: str, body: dict):
+    """Replace the trip's available tag list."""
+    trip = await fstore.doc_get("trips", trip_id)
+    if not trip:
+        raise HTTPException(404, f"Trip '{trip_id}' not found.")
+    tags = [str(t) for t in body.get("available_tags", []) if t]
+    await fstore.doc_update("trips", trip_id, {"available_tags": tags})
+    return {"available_tags": tags}
+
+
 @router.delete("/{trip_id}")
 async def delete_trip(trip_id: str, _: dict = Depends(require_service_key_or_admin)):
     trip = await fstore.doc_get("trips", trip_id)
@@ -275,6 +311,7 @@ async def create_event(trip_id: str, body: TripEventCreate):
         "maps_link": body.maps_link,
         "place_id": body.place_id,
         "notes": body.notes,
+        "tags": body.tags,
         "attendees": {},
         "created_at": now,
     }
@@ -403,7 +440,19 @@ async def trip_chat(
         for tc in msg.tool_calls:
             args = json.loads(tc.function.arguments)
 
-            if tc.function.name == "search_places":
+            if tc.function.name == "add_tag":
+                new_tag = str(args.get("tag", "")).strip()[:50]
+                if new_tag and new_tag not in trip.get("available_tags", []):
+                    updated_tags = list(trip.get("available_tags") or []) + [new_tag]
+                    trip["available_tags"] = updated_tags
+                    await fstore.doc_update("trips", trip_id, {"available_tags": updated_tags})
+                messages.append({
+                    "role": "tool",
+                    "tool_call_id": tc.id,
+                    "content": json.dumps({"available_tags": trip.get("available_tags", [])}),
+                })
+
+            elif tc.function.name == "search_places":
                 # Limit query string lengths before hitting the Maps API
                 query = str(args.get("query", ""))[:200]
                 near = str(args.get("near", ""))[:200]
@@ -416,8 +465,10 @@ async def trip_chat(
 
             elif tc.function.name == "propose_event":
                 suggestion = {k: args.get(k) for k in (
-                    "title", "date", "start_time", "end_time", "location", "maps_link", "notes"
+                    "title", "date", "start_time", "end_time", "location", "maps_link", "notes", "tags"
                 )}
+                if not isinstance(suggestion.get("tags"), list):
+                    suggestion["tags"] = []
                 suggestions.append(suggestion)
                 messages.append({
                     "role": "tool",