Add show improvement features: crossfade, emotions, returning callers, transcripts, screening

- Music crossfade: smooth 3-second blend between tracks instead of hard stop/start
- Emotional detection: analyze host mood from recent messages so callers adapt tone
- AI caller summaries: generate call summaries with timestamps for show history
- Returning callers: persist regular callers across sessions with call history
- Session export: generate transcripts with speaker labels and chapter markers
- Caller screening: AI pre-screens phone callers to get name and topic while queued

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/services/regulars.py

@@ -0,0 +1,95 @@
+"""Returning caller persistence service"""
+
+import json
+import time
+import uuid
+from pathlib import Path
+from typing import Optional
+
+DATA_FILE = Path(__file__).parent.parent.parent / "data" / "regulars.json"
+MAX_REGULARS = 12
+
+
+class RegularCallerService:
+    """Manages persistent 'regular' callers who return across sessions"""
+
+    def __init__(self):
+        self._regulars: list[dict] = []
+        self._load()
+
+    def _load(self):
+        if DATA_FILE.exists():
+            try:
+                with open(DATA_FILE) as f:
+                    data = json.load(f)
+                self._regulars = data.get("regulars", [])
+                print(f"[Regulars] Loaded {len(self._regulars)} regular callers")
+            except Exception as e:
+                print(f"[Regulars] Failed to load: {e}")
+                self._regulars = []
+
+    def _save(self):
+        try:
+            DATA_FILE.parent.mkdir(parents=True, exist_ok=True)
+            with open(DATA_FILE, "w") as f:
+                json.dump({"regulars": self._regulars}, f, indent=2)
+        except Exception as e:
+            print(f"[Regulars] Failed to save: {e}")
+
+    def get_regulars(self) -> list[dict]:
+        return list(self._regulars)
+
+    def get_returning_callers(self, count: int = 2) -> list[dict]:
+        """Get up to `count` regulars for returning caller slots"""
+        import random
+        if not self._regulars:
+            return []
+        available = [r for r in self._regulars if len(r.get("call_history", [])) > 0]
+        if not available:
+            return []
+        return random.sample(available, min(count, len(available)))
+
+    def add_regular(self, name: str, gender: str, age: int, job: str,
+                    location: str, personality_traits: list[str],
+                    first_call_summary: str) -> dict:
+        """Promote a first-time caller to regular"""
+        # Retire oldest if at cap
+        if len(self._regulars) >= MAX_REGULARS:
+            self._regulars.sort(key=lambda r: r.get("last_call", 0))
+            retired = self._regulars.pop(0)
+            print(f"[Regulars] Retired {retired['name']} to make room")
+
+        regular = {
+            "id": str(uuid.uuid4())[:8],
+            "name": name,
+            "gender": gender,
+            "age": age,
+            "job": job,
+            "location": location,
+            "personality_traits": personality_traits,
+            "call_history": [
+                {"summary": first_call_summary, "timestamp": time.time()}
+            ],
+            "last_call": time.time(),
+            "created_at": time.time(),
+        }
+        self._regulars.append(regular)
+        self._save()
+        print(f"[Regulars] Promoted {name} to regular (total: {len(self._regulars)})")
+        return regular
+
+    def update_after_call(self, regular_id: str, call_summary: str):
+        """Update a regular's history after a returning call"""
+        for regular in self._regulars:
+            if regular["id"] == regular_id:
+                regular.setdefault("call_history", []).append(
+                    {"summary": call_summary, "timestamp": time.time()}
+                )
+                regular["last_call"] = time.time()
+                self._save()
+                print(f"[Regulars] Updated {regular['name']} call history ({len(regular['call_history'])} calls)")
+                return
+        print(f"[Regulars] Regular {regular_id} not found for update")
+
+
+regular_caller_service = RegularCallerService()