fix: move NAM block size sync before JACK client restart

The profile change handler was calling nam_host.set_block_size() AFTER
jack_client.start(), creating a race where the JACK callback fired with
the new buffer size while the old NAM subprocess was still running at
the old block_size. Pipe byte counts desynced => NAM returned passthrough.

+ also: auto_connect disable during restart, connect_fx_ports reorder,
  Tone3000 gear/sort/pagination params, NAM engine switch API endpoints

src/web/server.py

@@ -1051,6 +1051,29 @@ class WebServer:
                 "current": nam.current_model.name if nam.current_model else None,
             }
 
+        @app.get("/api/nam/engine")
+        async def get_nam_engine(channel: str = "guitar"):
+            """Get current NAM engine mode."""
+            _pm, _pl, nam, _ir = self._channel_deps(channel)
+            if not nam:
+                raise HTTPException(status_code=503)
+            mode = getattr(nam, 'engine_mode', 'cpp')
+            return {"engine_mode": mode}
+
+        @app.post("/api/nam/engine")
+        async def set_nam_engine(data: dict, channel: str = "guitar"):
+            """Switch NAM engine between 'cpp' and 'pytorch'."""
+            _pm, _pl, nam, _ir = self._channel_deps(channel)
+            if not nam:
+                raise HTTPException(status_code=503)
+            mode = data.get("engine_mode", "cpp")
+            if mode not in ("cpp", "pytorch"):
+                raise HTTPException(status_code=400, detail="engine_mode must be 'cpp' or 'pytorch'")
+            ok = nam.set_engine(mode)
+            if not ok:
+                raise HTTPException(status_code=500, detail=f"Failed to switch to {mode} engine")
+            return {"ok": True, "engine_mode": mode}
+
         @app.post("/api/models/load")
         async def load_model(data: dict, channel: str = "guitar"):
             """Load a NAM model by path for the given channel."""
@@ -1486,12 +1509,17 @@ class WebServer:
                     logger.warning("jack_client.stop() failed (expected if JACK was mid-callback)")
 
             # Start JACK with new parameters
-            ok = audio_sys.start_jack(timeout=10)
+            # Disable auto_connect temporarily — fx_in/fx_out ports don't
+            # exist until jack_client.start() recreates the JACK client below
+            saved_auto_connect = audio_sys.config.auto_connect
+            audio_sys.config.auto_connect = False
+            ok = audio_sys.start_jack(timeout=15)
+            audio_sys.config.auto_connect = saved_auto_connect
             if not ok:
                 # Rollback on failure
                 audio_sys.config.profile = old_key
                 logger.warning("JACK restart failed — attempting rollback to %s", old_key)
-                audio_sys.start_jack(timeout=10)
+                audio_sys.start_jack(timeout=15)
                 if jack_client:
                     try:
                         jack_client.start()
@@ -1502,6 +1530,13 @@ class WebServer:
                     detail=f"Failed to start JACK with period={target_profile['period']}, rate={target_profile['rate']} — rolled back",
                 )
 
+            # Sync NAM engine block size BEFORE restarting JACK client
+            # so the NAM subprocess is already sized for the new period
+            # when the process callback starts firing.
+            nam_host = self.deps.nam_host
+            if nam_host and hasattr(nam_host, 'set_block_size'):
+                nam_host.set_block_size(target_profile["period"])
+
             # Restart JACK audio client
             if jack_client:
                 try:
@@ -1509,10 +1544,12 @@ class WebServer:
                 except Exception as e:
                     logger.warning("jack_client.start() failed after profile switch: %s", e)
 
-            # Sync NAM engine block size
-            nam_host = self.deps.nam_host
-            if nam_host and hasattr(nam_host, 'set_block_size'):
-                nam_host.set_block_size(target_profile["period"])
+            # Reconnect FX ports now that pipeline's JACK client is alive
+            if saved_auto_connect:
+                try:
+                    audio_sys.connect_fx_ports()
+                except Exception as e:
+                    logger.warning("connect_fx_ports() failed after profile switch: %s", e)
 
             # ── Persist to config.yaml ──────────────────────────────
             if self.deps.config is not None:
@@ -1751,7 +1788,7 @@ class WebServer:
             return {"online": ok}
 
         @app.get("/api/models/tonedownload/search")
-        async def tonedownload_search_models(q: str = "", page: int = 0, arch: str = ""):
+        async def tonedownload_search_models(q: str = "", page: int = 0, arch: str = "", gear: str = "", sort: str = "created_at.desc"):
             """Search Tone3000 for NAM models."""
             try:
                 client = await self._get_tonedownload()
@@ -1765,10 +1802,11 @@ class WebServer:
                         },
                     )
                 arch_val = arch.strip() or None
+                gear_val = gear.strip() or None
                 if not q.strip():
-                    results = await client.get_trending_models(arch=arch_val)
+                    results = await client.get_trending_models(arch=arch_val, gear=gear_val)
                 else:
-                    results = await client.search_models(q.strip(), page=page, arch=arch_val)
+                    results = await client.search_models(q.strip(), page=page, arch=arch_val, gear=gear_val, sort=sort)
                 return {
                     "results": [
                         {
@@ -1786,9 +1824,12 @@ class WebServer:
                             "pack_name": r.pack_name,
                             "architecture": r.architecture,
                             "created_at": r.created_at,
+                            "downloads": r.downloads,
+                            "likes": r.likes,
                         }
                         for r in results
                     ],
+                    "page": page,
                 }
             except Exception as e:
                 logger.warning("Tone3000 model search failed: %s", e)