feat(app): provider system overhaul with model selector, diagnostics, and UX polish

- Add CombinedModelSelector with two-level drill-down (providers → models),
  favorites section, search, and single-provider auto-drill mode
- Add provider snapshot system (ProviderSnapshotManager) for cached provider/model state
- Add provider diagnostics with resolved binary paths and versions across all providers
- Add StatusBadge shared component for consistent status visual language
- Add ProviderDiagnosticSheet for detailed provider health inspection
- Add desktop auto-focus on input after any status bar interaction (model, mode,
  thinking, features) using focusWithRetries
- Fix Combobox flicker on height change by switching to bottom-based CSS positioning
  once initial floating-ui position resolves
- Add dynamic dropdown height: Level 1 fits content, Level 2 calculates from model count
- Remove "Other providers" section from model selector (only show available providers)

packages/server/src/client/daemon-client.ts

@@ -43,6 +43,9 @@ import type {
   ListAvailableProvidersResponse,
   ListTerminalsResponse,
   CreateTerminalResponse,
+  GetProvidersSnapshotResponseMessage,
+  ProviderDiagnosticResponseMessage,
+  RefreshProvidersSnapshotResponseMessage,
   SubscribeTerminalResponse,
   TerminalState,
   CloseItemsResponse,
@@ -147,6 +150,10 @@ export type DaemonEvent =
       requestId: string;
       resolution: AgentPermissionResponse;
     }
+  | {
+      type: "providers_snapshot_update";
+      payload: Extract<SessionOutboundMessage, { type: "providers_snapshot_update" }>["payload"];
+    }
   | { type: "error"; message: string };
 
 export type DaemonEventHandler = (event: DaemonEvent) => void;
@@ -222,6 +229,9 @@ type ListProviderFeaturesPayload = ListProviderFeaturesResponseMessage["payload"
 type ListProviderModelsPayload = ListProviderModelsResponseMessage["payload"];
 type ListProviderModesPayload = ListProviderModesResponseMessage["payload"];
 type ListAvailableProvidersPayload = ListAvailableProvidersResponse["payload"];
+type GetProvidersSnapshotPayload = GetProvidersSnapshotResponseMessage["payload"];
+type RefreshProvidersSnapshotPayload = RefreshProvidersSnapshotResponseMessage["payload"];
+type ProviderDiagnosticPayload = ProviderDiagnosticResponseMessage["payload"];
 type ListCommandsPayload = ListCommandsResponse["payload"];
 type ListCommandsDraftConfig = Pick<
   AgentSessionConfig,
@@ -2552,6 +2562,51 @@ export class DaemonClient {
     });
   }
 
+  async getProvidersSnapshot(options?: {
+    cwd?: string;
+    requestId?: string;
+  }): Promise<GetProvidersSnapshotPayload> {
+    return this.sendCorrelatedSessionRequest({
+      requestId: options?.requestId,
+      message: {
+        type: "get_providers_snapshot_request",
+        cwd: options?.cwd,
+      },
+      responseType: "get_providers_snapshot_response",
+      timeout: 10000,
+    });
+  }
+
+  async refreshProvidersSnapshot(options?: {
+    cwd?: string;
+    requestId?: string;
+  }): Promise<RefreshProvidersSnapshotPayload> {
+    return this.sendCorrelatedSessionRequest({
+      requestId: options?.requestId,
+      message: {
+        type: "refresh_providers_snapshot_request",
+        cwd: options?.cwd,
+      },
+      responseType: "refresh_providers_snapshot_response",
+      timeout: 5000,
+    });
+  }
+
+  async getProviderDiagnostic(
+    provider: AgentProvider,
+    options?: { requestId?: string },
+  ): Promise<ProviderDiagnosticPayload> {
+    return this.sendCorrelatedSessionRequest({
+      requestId: options?.requestId,
+      message: {
+        type: "provider_diagnostic_request",
+        provider,
+      },
+      responseType: "provider_diagnostic_response",
+      timeout: 30000,
+    });
+  }
+
   async listCommands(agentId: string, requestId?: string): Promise<ListCommandsPayload>;
   async listCommands(agentId: string, options?: ListCommandsOptions): Promise<ListCommandsPayload>;
   async listCommands(
@@ -3637,6 +3692,11 @@ export class DaemonClient {
           requestId: msg.payload.requestId,
           resolution: msg.payload.resolution,
         };
+      case "providers_snapshot_update":
+        return {
+          type: "providers_snapshot_update",
+          payload: msg.payload,
+        };
       default:
         return null;
     }