feat: fallback model range slider with live label, model-changed event

- Added model-changed event: backend emits it on fallback, frontend updates tab keyId/modelId
- Range slider embedded inside active agent card when >1 model configured
- Live label updates on drag (oninput), backend call only on release (onchange)
- Slider auto-positions when fallback occurs via model-changed WS event

1 files changed, 4 insertions, 0 deletions

diff --git a/packages/api/src/agent-manager.ts b/packages/api/src/agent-manager.ts
index 828855c..5b19eb3 100644
--- a/packages/api/src/agent-manager.ts
+++ b/packages/api/src/agent-manager.ts
@@ -984,6 +984,10 @@ export class AgentManager {
 						`Falling back to "${nextEntry.key_id}" (model: ${nextEntry.model_id})...`;
 					console.warn(`[dispatch] ${fallbackMsg}`);
 					this.emit({ type: "notice", message: fallbackMsg }, tabId);
+					this.emit(
+						{ type: "model-changed", keyId: nextEntry.key_id, modelId: nextEntry.model_id },
+						tabId,
+					);
 					tabAgent.agent = null;
 					continue;
 				}