backend, web: support for resuming streams

web/src/lib/api.ts

@@ -139,6 +139,11 @@ export type ModelCatalogResponse = {
   providers: Record<Provider, ProviderModelInfo>;
 };
 
+export type ActiveRunsResponse = {
+  chats: string[];
+  searches: string[];
+};
+
 type CompletionResponse = {
   chatId: string | null;
   message: {
@@ -217,6 +222,10 @@ export async function listModels() {
   return api<ModelCatalogResponse>("/v1/models");
 }
 
+export async function getActiveRuns() {
+  return api<ActiveRunsResponse>("/v1/active-runs");
+}
+
 export async function createChat(input?: string | CreateChatRequest) {
   const body = typeof input === "string" ? { title: input } : input ?? {};
   const data = await api<{ chat: ChatSummary }>("/v1/chats", {
@@ -333,6 +342,85 @@ type RunSearchStreamHandlers = {
   onError?: (payload: { message: string }) => void;
 };
 
+async function readSseStream(response: Response, dispatch: (eventName: string, payload: any) => void) {
+  if (!response.ok) {
+    const fallback = `${response.status} ${response.statusText}`;
+    let message = fallback;
+    try {
+      const body = (await response.json()) as { message?: string };
+      if (body.message) message = body.message;
+    } catch {
+      // keep fallback message
+    }
+    throw new Error(message);
+  }
+
+  if (!response.body) {
+    throw new Error("No response stream");
+  }
+
+  const reader = response.body.getReader();
+  const decoder = new TextDecoder();
+  let buffer = "";
+  let eventName = "message";
+  let dataLines: string[] = [];
+
+  const flushEvent = () => {
+    if (!dataLines.length) {
+      eventName = "message";
+      return;
+    }
+
+    const dataText = dataLines.join("\n");
+    let payload: any = null;
+    try {
+      payload = JSON.parse(dataText);
+    } catch {
+      payload = { message: dataText };
+    }
+
+    dispatch(eventName, payload);
+
+    dataLines = [];
+    eventName = "message";
+  };
+
+  while (true) {
+    const { value, done } = await reader.read();
+    if (done) break;
+
+    buffer += decoder.decode(value, { stream: true });
+    let newlineIndex = buffer.indexOf("\n");
+
+    while (newlineIndex >= 0) {
+      const rawLine = buffer.slice(0, newlineIndex);
+      buffer = buffer.slice(newlineIndex + 1);
+      const line = rawLine.endsWith("\r") ? rawLine.slice(0, -1) : rawLine;
+
+      if (!line) {
+        flushEvent();
+      } else if (line.startsWith("event:")) {
+        eventName = line.slice("event:".length).trim();
+      } else if (line.startsWith("data:")) {
+        dataLines.push(line.slice("data:".length).trimStart());
+      }
+
+      newlineIndex = buffer.indexOf("\n");
+    }
+  }
+
+  buffer += decoder.decode();
+  if (buffer.length) {
+    const line = buffer.endsWith("\r") ? buffer.slice(0, -1) : buffer;
+    if (line.startsWith("event:")) {
+      eventName = line.slice("event:".length).trim();
+    } else if (line.startsWith("data:")) {
+      dataLines.push(line.slice("data:".length).trimStart());
+    }
+  }
+  flushEvent();
+}
+
 export async function runSearchStream(
   searchId: string,
   body: SearchRunRequest,
@@ -437,6 +525,30 @@ export async function runSearchStream(
   flushEvent();
 }
 
+export async function attachSearchStream(searchId: string, handlers: RunSearchStreamHandlers, options?: { signal?: AbortSignal }) {
+  const headers = new Headers({
+    Accept: "text/event-stream",
+  });
+  if (authToken) {
+    headers.set("Authorization", `Bearer ${authToken}`);
+  }
+
+  const response = await fetch(`${API_BASE_URL}/v1/searches/${searchId}/run/stream/attach`, {
+    method: "POST",
+    headers,
+    signal: options?.signal,
+  });
+
+  await readSseStream(response, (eventName, payload) => {
+    if (eventName === "search_results") handlers.onSearchResults?.(payload);
+    else if (eventName === "search_error") handlers.onSearchError?.(payload);
+    else if (eventName === "answer") handlers.onAnswer?.(payload);
+    else if (eventName === "answer_error") handlers.onAnswerError?.(payload);
+    else if (eventName === "done") handlers.onDone?.(payload);
+    else if (eventName === "error") handlers.onError?.(payload);
+  });
+}
+
 export async function runCompletion(body: {
   chatId: string;
   provider: Provider;
@@ -556,3 +668,26 @@ export async function runCompletionStream(
   }
   flushEvent();
 }
+
+export async function attachCompletionStream(chatId: string, handlers: CompletionStreamHandlers, options?: { signal?: AbortSignal }) {
+  const headers = new Headers({
+    Accept: "text/event-stream",
+  });
+  if (authToken) {
+    headers.set("Authorization", `Bearer ${authToken}`);
+  }
+
+  const response = await fetch(`${API_BASE_URL}/v1/chats/${chatId}/stream/attach`, {
+    method: "POST",
+    headers,
+    signal: options?.signal,
+  });
+
+  await readSseStream(response, (eventName, payload) => {
+    if (eventName === "meta") handlers.onMeta?.(payload);
+    else if (eventName === "tool_call") handlers.onToolCall?.(payload);
+    else if (eventName === "delta") handlers.onDelta?.(payload);
+    else if (eventName === "done") handlers.onDone?.(payload);
+    else if (eventName === "error") handlers.onError?.(payload);
+  });
+}