feat(tess): wire durable interaction surfaces (#732)

packages/mosaic/src/tui/gateway-api.ts

@@ -406,6 +406,32 @@ export async function fetchInteractionTree(
   return handleResponse<unknown[]>(res, 'Failed to get interaction session tree');
 }
 
+export async function enrollInteractionSession(
+  gatewayUrl: string,
+  sessionCookie: string,
+  request: InteractionRequest & {
+    sessionId: string;
+    providerId: string;
+    runtimeSessionId: string;
+  },
+): Promise<{ status: string; sessionId: string }> {
+  const res = await fetch(
+    `${gatewayUrl}${interactionPath(request.agentName, `/sessions/${encodeURIComponent(request.sessionId)}/enroll`)}`,
+    {
+      method: 'POST',
+      headers: interactionHeaders(sessionCookie, gatewayUrl, request.correlationId),
+      body: JSON.stringify({
+        providerId: request.providerId,
+        runtimeSessionId: request.runtimeSessionId,
+      }),
+    },
+  );
+  return handleResponse<{ status: string; sessionId: string }>(
+    res,
+    'Failed to enroll interaction session',
+  );
+}
+
 export async function attachInteractionSession(
   gatewayUrl: string,
   sessionCookie: string,
@@ -422,6 +448,49 @@ export async function attachInteractionSession(
   return handleResponse<unknown>(res, 'Failed to attach interaction session');
 }
 
+export async function* streamInteractionSession(
+  gatewayUrl: string,
+  sessionCookie: string,
+  request: InteractionRequest & { sessionId: string; cursor?: string },
+): AsyncIterable<unknown> {
+  const params = request.cursor?.trim()
+    ? `?${new URLSearchParams({ cursor: request.cursor.trim() }).toString()}`
+    : '';
+  const res = await fetch(
+    `${gatewayUrl}${interactionPath(request.agentName, `/sessions/${encodeURIComponent(request.sessionId)}/stream${params}`)}`,
+    { headers: interactionHeaders(sessionCookie, gatewayUrl, request.correlationId) },
+  );
+  if (!res.ok || !res.body) {
+    const body = await res.text().catch(() => '');
+    throw new Error(`Failed to stream interaction session (${res.status}): ${body}`);
+  }
+
+  const reader = res.body.getReader();
+  const decoder = new TextDecoder();
+  let pending = '';
+  try {
+    for (;;) {
+      const chunk = await reader.read();
+      if (chunk.done) break;
+      pending += decoder.decode(chunk.value, { stream: true });
+      for (;;) {
+        const separator = pending.indexOf('\n\n');
+        if (separator < 0) break;
+        const frame = pending.slice(0, separator);
+        pending = pending.slice(separator + 2);
+        const data = frame
+          .split('\n')
+          .find((line: string): boolean => line.startsWith('data:'))
+          ?.slice('data:'.length)
+          .trim();
+        if (data) yield JSON.parse(data) as unknown;
+      }
+    }
+  } finally {
+    reader.releaseLock();
+  }
+}
+
 export async function sendInteractionMessage(
   gatewayUrl: string,
   sessionCookie: string,