Fix TUI config generator reactive updates and head config format

- Add reactive YAML preview updates when form values change (pipeline,
  backbone, inputs, switches, selects)
- Set default pipeline selection to Single Instance
- Update head_configs to include all head types (matching expected format)
- Add missing event handlers for Switch and Select widgets

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: gitttt-1234

sleap_nn/config_generator/generator.py

@@ -517,69 +517,75 @@ def _build_model_config(self) -> dict:
         }
 
     def _build_head_config(self) -> dict:
-        """Build head configuration based on pipeline type."""
+        """Build head configuration based on pipeline type.
+
+        Returns config with all head types, setting the active one's config
+        and null for all others (matches expected sleap-nn config format).
+        """
         base_confmap = {
             "sigma": self._sigma,
             "output_stride": self._output_stride,
         }
 
+        # Initialize all head types to null
+        head_configs = {
+            "single_instance": None,
+            "centroid": None,
+            "centered_instance": None,
+            "bottomup": None,
+            "multi_class_bottomup": None,
+            "multi_class_topdown": None,
+        }
+
         if self._pipeline == "single_instance":
-            return {"single_instance": {"confmaps": base_confmap}}
+            head_configs["single_instance"] = {"confmaps": base_confmap}
 
         elif self._pipeline == "centroid":
-            cfg = {"confmaps": base_confmap.copy()}
-            if self._anchor_part:
-                cfg["anchor_part"] = self._anchor_part
-            return {"centroid": cfg}
+            cfg = {"confmaps": {**base_confmap, "anchor_part": self._anchor_part}}
+            head_configs["centroid"] = cfg
 
         elif self._pipeline == "centered_instance":
-            cfg = {"confmaps": base_confmap.copy()}
-            if self._anchor_part:
-                cfg["anchor_part"] = self._anchor_part
-            return {"centered_instance": cfg}
+            cfg = {"confmaps": {**base_confmap, "anchor_part": self._anchor_part}}
+            head_configs["centered_instance"] = cfg
 
         elif self._pipeline == "bottomup":
-            return {
-                "bottomup": {
-                    "confmaps": {
-                        **base_confmap,
-                        "loss_weight": 1.0,
-                    },
-                    "pafs": {
-                        "sigma": 15.0,  # PAFs use larger sigma
-                        "output_stride": max(self._output_stride, 4),
-                        "loss_weight": 1.0,
-                    },
-                }
+            head_configs["bottomup"] = {
+                "confmaps": {
+                    **base_confmap,
+                    "loss_weight": 1.0,
+                },
+                "pafs": {
+                    "sigma": 15.0,  # PAFs use larger sigma
+                    "output_stride": max(self._output_stride, 4),
+                    "loss_weight": 1.0,
+                },
             }
 
         elif self._pipeline == "multi_class_bottomup":
-            return {
-                "multi_class_bottomup": {
-                    "confmaps": {**base_confmap, "loss_weight": 1.0},
-                    "pafs": {
-                        "sigma": 15.0,
-                        "output_stride": max(self._output_stride, 4),
-                        "loss_weight": 1.0,
-                    },
-                    "class_vectors": {
-                        "num_fc_layers": 1,
-                        "num_fc_units": 64,
-                    },
-                }
+            head_configs["multi_class_bottomup"] = {
+                "confmaps": {**base_confmap, "loss_weight": 1.0},
+                "pafs": {
+                    "sigma": 15.0,
+                    "output_stride": max(self._output_stride, 4),
+                    "loss_weight": 1.0,
+                },
+                "class_vectors": {
+                    "num_fc_layers": 1,
+                    "num_fc_units": 64,
+                },
             }
 
         elif self._pipeline == "multi_class_topdown":
-            cfg = {"confmaps": base_confmap.copy()}
-            if self._anchor_part:
-                cfg["anchor_part"] = self._anchor_part
-            cfg["class_vectors"] = {
-                "num_fc_layers": 1,
-                "num_fc_units": 64,
+            cfg = {
+                "confmaps": {**base_confmap, "anchor_part": self._anchor_part},
+                "class_vectors": {
+                    "num_fc_layers": 1,
+                    "num_fc_units": 64,
+                },
             }
-            return {"multi_class_topdown": cfg}
+            head_configs["multi_class_topdown"] = cfg
 
-        return {}
+        return head_configs
 
     def _build_trainer_config(self) -> dict:
         """Build trainer configuration section."""

sleap_nn/config_generator/tui/app.py

@@ -217,6 +217,7 @@ def __init__(self, slp_path: str, **kwargs):
 
         Args:
             slp_path: Path to the SLP file to analyze.
+            **kwargs: Additional arguments passed to parent App class.
         """
         super().__init__(**kwargs)
         self.slp_path = Path(slp_path)
@@ -280,7 +281,7 @@ def _compose_model_tab(self) -> ComposeResult:
         with VerticalScroll():
             yield Static("Pipeline Type", classes="section-title")
             with RadioSet(id="pipeline-select"):
-                yield RadioButton("Single Instance", id="pipe-single")
+                yield RadioButton("Single Instance", id="pipe-single", value=True)
                 yield RadioButton("Top-Down: Centroid", id="pipe-centroid")
                 yield RadioButton("Top-Down: Centered Instance", id="pipe-centered")
                 yield RadioButton("Bottom-Up", id="pipe-bottomup")
@@ -733,13 +734,31 @@ def handle_radio_change(self, event: RadioSet.Changed) -> None:
         if event.radio_set.id == "backbone-select":
             self._update_memory_estimate()
 
+        # Update YAML preview when pipeline or backbone changes
+        if event.radio_set.id in ["pipeline-select", "backbone-select"]:
+            self._update_yaml_preview()
+
     @on(Input.Changed)
     def handle_input_change(self, event: Input.Changed) -> None:
         """Handle input field changes."""
         # Update memory estimate for relevant fields
         if event.input.id in ["batch-size-input", "sigma-input"]:
             self._update_memory_estimate()
 
+        # Update YAML preview for all input changes
+        self._update_yaml_preview()
+
+    @on(Switch.Changed)
+    def handle_switch_change(self, event: Switch.Changed) -> None:
+        """Handle switch changes."""
+        self._update_yaml_preview()
+
+    @on(Select.Changed)
+    def handle_select_change(self, event: Select.Changed) -> None:
+        """Handle select changes."""
+        self._update_yaml_preview()
+        self._update_memory_estimate()
+
     def action_quit(self) -> None:
         """Quit the application."""
         self.exit()