feat(proxy-engine): add device leg, leg transfer, and leg replacement call controls

ts/proxybridge.ts

@@ -41,6 +41,18 @@ type TProxyCommands = {
     params: { call_id: string };
     result: { file_path: string; duration_ms: number };
   };
+  add_device_leg: {
+    params: { call_id: string; device_id: string };
+    result: { leg_id: string };
+  };
+  transfer_leg: {
+    params: { source_call_id: string; leg_id: string; target_call_id: string };
+    result: Record<string, never>;
+  };
+  replace_leg: {
+    params: { call_id: string; old_leg_id: string; number: string; provider_id?: string };
+    result: { new_leg_id: string };
+  };
   start_interaction: {
     params: {
       call_id: string;
@@ -307,9 +319,72 @@ export async function webrtcClose(sessionId: string): Promise<void> {
 }
 
 // ---------------------------------------------------------------------------
-// Leg interaction & tool leg commands
+// Device leg & interaction commands
 // ---------------------------------------------------------------------------
 
+/**
+ * Add a local SIP device to an existing call (mid-call INVITE to desk phone).
+ */
+export async function addDeviceLeg(callId: string, deviceId: string): Promise<string | null> {
+  if (!bridge || !initialized) return null;
+  try {
+    const result = await bridge.sendCommand('add_device_leg', {
+      call_id: callId,
+      device_id: deviceId,
+    } as any);
+    return (result as any)?.leg_id || null;
+  } catch (e: any) {
+    logFn?.(`[proxy-engine] add_device_leg error: ${e?.message || e}`);
+    return null;
+  }
+}
+
+/**
+ * Transfer a leg from one call to another (leg stays connected, switches mixer).
+ */
+export async function transferLeg(
+  sourceCallId: string,
+  legId: string,
+  targetCallId: string,
+): Promise<boolean> {
+  if (!bridge || !initialized) return false;
+  try {
+    await bridge.sendCommand('transfer_leg', {
+      source_call_id: sourceCallId,
+      leg_id: legId,
+      target_call_id: targetCallId,
+    } as any);
+    return true;
+  } catch (e: any) {
+    logFn?.(`[proxy-engine] transfer_leg error: ${e?.message || e}`);
+    return false;
+  }
+}
+
+/**
+ * Replace a leg: terminate the old leg and dial a new number into the same call.
+ */
+export async function replaceLeg(
+  callId: string,
+  oldLegId: string,
+  number: string,
+  providerId?: string,
+): Promise<string | null> {
+  if (!bridge || !initialized) return null;
+  try {
+    const result = await bridge.sendCommand('replace_leg', {
+      call_id: callId,
+      old_leg_id: oldLegId,
+      number,
+      provider_id: providerId,
+    } as any);
+    return (result as any)?.new_leg_id || null;
+  } catch (e: any) {
+    logFn?.(`[proxy-engine] replace_leg error: ${e?.message || e}`);
+    return null;
+  }
+}
+
 /**
  * Start an interaction on a specific leg — isolate it, play a prompt, collect DTMF.
  * Blocks until the interaction completes (digit pressed, timeout, or cancelled).