feat: add structured part events to gateway for teamActivity, media, and error parts

Extends GatewayEvent union with structured_part variants, adds matching
HistoryPart types, wires SSE emission in runtime handleChat, and maps
agent-core content parts to history in session-state.

packages/coding-agent/src/core/gateway/runtime.ts

@@ -7,6 +7,7 @@ import {
 import { rm } from "node:fs/promises";
 import { join } from "node:path";
 import { URL } from "node:url";
+import type { AgentMessage } from "@mariozechner/companion-agent-core";
 import type { AgentSession, AgentSessionEvent } from "../agent-session.js";
 import type { Settings } from "../settings-manager.js";
 import { extractMessageText, getLastAssistantText } from "./helpers.js";
@@ -29,6 +30,7 @@ import type {
   ModelInfo,
 } from "./types.js";
 import {
+  createGatewayStructuredPartListener,
   createVercelStreamListener,
   errorVercelStream,
   extractUserText,
@@ -567,6 +569,7 @@ export class GatewayRuntime {
             sessionKey: managedSession.sessionKey,
             text: extractMessageText(event.message),
           });
+          this.emitStructuredParts(managedSession, event.message);
           return;
         }
         if (event.message.role === "toolResult") {
@@ -654,6 +657,73 @@ export class GatewayRuntime {
     });
   }
 
+  private emitStructuredParts(
+    managedSession: ManagedGatewaySession,
+    message: AgentMessage,
+  ): void {
+    const content = message.content;
+    if (!Array.isArray(content)) return;
+
+    for (const part of content) {
+      if (typeof part !== "object" || part === null) continue;
+      const p = part as Record<string, unknown>;
+
+      if (p.type === "teamActivity") {
+        const teamId = typeof p.teamId === "string" ? p.teamId : "";
+        const status = typeof p.status === "string" ? p.status : "running";
+        if (!teamId) continue;
+        const rawMembers = Array.isArray(p.members) ? p.members : [];
+        const members = rawMembers
+          .filter((m): m is Record<string, unknown> => typeof m === "object" && m !== null)
+          .map((m) => ({
+            id: typeof m.id === "string" ? m.id : "",
+            name: typeof m.name === "string" ? m.name : "Teammate",
+            ...(typeof m.role === "string" ? { role: m.role } : {}),
+            status: typeof m.status === "string" ? m.status : "running",
+            ...(typeof m.message === "string" ? { message: m.message } : {}),
+          }))
+          .filter((m) => m.id.length > 0);
+        this.emit(managedSession, {
+          type: "structured_part",
+          sessionKey: managedSession.sessionKey,
+          partType: "teamActivity",
+          payload: { teamId, status, members },
+        });
+        continue;
+      }
+
+      if (p.type === "image") {
+        const url = typeof p.url === "string" ? p.url : "";
+        if (!url) continue;
+        this.emit(managedSession, {
+          type: "structured_part",
+          sessionKey: managedSession.sessionKey,
+          partType: "media",
+          payload: {
+            url,
+            ...(typeof p.mimeType === "string" ? { mimeType: p.mimeType } : {}),
+          },
+        });
+        continue;
+      }
+
+      if (p.type === "error") {
+        const errorMessage = typeof p.message === "string" ? p.message : "";
+        if (!errorMessage) continue;
+        this.emit(managedSession, {
+          type: "structured_part",
+          sessionKey: managedSession.sessionKey,
+          partType: "error",
+          payload: {
+            code: typeof p.code === "string" ? p.code : "unknown",
+            message: errorMessage,
+          },
+        });
+        continue;
+      }
+    }
+  }
+
   private createSessionState(
     managedSession: ManagedGatewaySession,
   ): GatewaySessionState {
@@ -1106,7 +1176,9 @@ export class GatewayRuntime {
     response.write("\n");
 
     const listener = createVercelStreamListener(response);
+    const structuredPartListener = createGatewayStructuredPartListener(response);
     let unsubscribe: (() => void) | undefined;
+    let unsubscribeStructured: (() => void) | undefined;
     let streamingActive = false;
 
     const stopStreaming = () => {
@@ -1114,6 +1186,8 @@ export class GatewayRuntime {
       streamingActive = false;
       unsubscribe?.();
       unsubscribe = undefined;
+      unsubscribeStructured?.();
+      unsubscribeStructured = undefined;
     };
 
     // Clean up on client disconnect
@@ -1135,6 +1209,10 @@ export class GatewayRuntime {
         onStart: () => {
           if (clientDisconnected || streamingActive) return;
           unsubscribe = managedSession.session.subscribe(listener);
+          managedSession.listeners.add(structuredPartListener);
+          unsubscribeStructured = () => {
+            managedSession.listeners.delete(structuredPartListener);
+          };
           streamingActive = true;
         },
         onFinish: () => {