Append-only picks store with user-initiated dismiss

Pipeline:
- write_picks() no longer truncates; deduplicates by artist+album
  key on append so the same pick is never added twice
- Picks accumulate indefinitely; only the user can remove them

New endpoint POST /api/fgs/picks/remove:
- Accepts {artist, album}, removes matching pick from store
- Also writes the removed pick to the dedup DB so it won't resurface

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

agent.py

@@ -749,7 +749,17 @@ async def write_picks(new_picks: list[dict], run_stats: dict):
         "candidatesFiltered": run_stats.get("filtered", 0),
     }
     store["runs"] = ([run] + store.get("runs", []))[:10]
-    store["allPicks"] = (new_picks + store.get("allPicks", []))[:200]
+    # Append-only — never remove existing picks; dedup by artist+album key
+    existing = store.get("allPicks", [])
+    existing_keys = {
+        (p.get("artist", "").lower(), p.get("album", "").lower())
+        for p in existing
+    }
+    truly_new = [
+        p for p in new_picks
+        if (p.get("artist", "").lower(), p.get("album", "").lower()) not in existing_keys
+    ]
+    store["allPicks"] = truly_new + existing
     store["lastUpdated"] = run["timestamp"]
 
     with open(settings.picks_path, "w") as f:
@@ -889,6 +899,38 @@ async def get_picks():
         return JSONResponse({"error": str(e)}, status_code=500)
 
 
+class RemoveRequest(BaseModel):
+    artist: str
+    album: str
+
+
+@app.post("/api/fgs/picks/remove")
+async def remove_pick(req: RemoveRequest):
+    """User-initiated pick removal. Writes the pick key to dedup so it won't return."""
+    try:
+        with open(settings.picks_path, "r") as f:
+            store = json.load(f)
+    except Exception as e:
+        return JSONResponse({"error": str(e)}, status_code=500)
+
+    key_a = req.artist.lower()
+    key_b = req.album.lower()
+    before = len(store.get("allPicks", []))
+    store["allPicks"] = [
+        p for p in store.get("allPicks", [])
+        if not (p.get("artist", "").lower() == key_a and p.get("album", "").lower() == key_b)
+    ]
+    after = len(store["allPicks"])
+
+    with open(settings.picks_path, "w") as f:
+        json.dump(store, f, indent=2)
+
+    # Also add to dedup so it won't come back
+    await mark_seen([{"artist": req.artist, "album": req.album}])
+
+    return {"removed": before - after, "total": after}
+
+
 @app.get("/api/fgs/health")
 async def health():
     return {"status": "ok", "agent": "fgs-agent"}