Resume original work-session history after an interrupted read

apps/presentation/dashboard/src/features/personal-workspace/attached-agent-conversations.tsx

@@ -16,7 +16,12 @@ type LiveObservation = {kind: "records"; revision: number; records: Message[]} |
   {kind: "unavailable"; retry: boolean};
 
 class ConversationRequestError extends Error {
-  constructor(message: string, readonly unsubmittedOperation?: string, readonly httpStatus?: number) {super(message);}
+  constructor(
+    message: string,
+    readonly unsubmittedOperation?: string,
+    readonly httpStatus?: number,
+    readonly interruptedSuccessfulResponse = false,
+  ) {super(message);}
 }
 
 export async function request<T>(url: string, options?: RequestInit): Promise<T> {
@@ -30,11 +35,9 @@ export async function request<T>(url: string, options?: RequestInit): Promise<T>
   try {
     body = await response.text();
   } catch {
-    // The headers arrived, so the status is already known even though the body
-    // did not. Drop the status here and a stalled 503 body looks like a plain
-    // transport failure while a truncated 403 body looks retryable; the caller
-    // must classify on this status, not on how the body read failed.
-    throw new ConversationRequestError("Conversation unavailable", undefined, response.status);
+    // Preserve rejected statuses even when their bodies drop. A successful
+    // response interrupted in transit is different from a complete invalid body.
+    throw new ConversationRequestError("Conversation unavailable", undefined, response.status, response.ok);
   }
   let value: Record<string, unknown> | null = null;
   try {value = body ? JSON.parse(body) as Record<string, unknown> : null;} catch {value = null;}
@@ -51,7 +54,8 @@ function interruptedRead(failure: unknown): boolean {
 }
 
 export function retryableRead(failure: unknown): boolean {
-  return interruptedRead(failure) || (failure instanceof ConversationRequestError && (failure.httpStatus ?? 0) >= 500);
+  return interruptedRead(failure) || (failure instanceof ConversationRequestError &&
+    (failure.interruptedSuccessfulResponse || (failure.httpStatus ?? 0) >= 500));
 }
 
 export function readFailureMessage(failure: unknown, zh: boolean): string {

examples/personal-workspace-browser/codex-attached.mjs

@@ -740,28 +740,41 @@ async function runConversation(browser, uncertain) {
     let releasePage, pageStarted;
     const heldPage = new Promise(resolve => {releasePage = resolve;});
     const pagingStarted = new Promise(resolve => {pageStarted = resolve;});
-    let held = false, historyOutage = true;
+    const olderReads = [];
     const holdHistory = async route => {
-      if (!new URL(route.request().url()).searchParams.has('before') || held) return route.continue();
-      if (historyOutage) {
-        historyOutage = false;
-        return route.fulfill({status:503,contentType:'text/html',body:'<html>Temporary history outage</html>'});
-      }
-      held = true;
+      const query = new URL(route.request().url()).searchParams;
+      if (!query.has('before') || olderReads.length === 2) return route.continue();
+      olderReads.push([query.get('before'), query.get('source_ref'), query.get('binding_ref')]);
+      if (olderReads.length === 1) return route.continue();
       const response = await route.fetch(); pageStarted(); await heldPage;
       await route.fulfill({response});
     };
+    await page.request.post(new URL('/fixture/history-body-drop',url).href);
     await page.route('**/api/chat/codex-attached?*',holdHistory);
     const transcript = panel.locator('.attached-conversation-messages');
+    const partial = page.waitForResponse(response =>
+      new URL(response.url()).searchParams.has('before') && response.status() === 200);
     await transcript.focus(); await page.keyboard.press('Home');
+    await partial;
     await panel.getByRole('alert').waitFor();
-    await Promise.race([pagingStarted, page.waitForTimeout(10_000).then(() => {throw new Error('Scrolling to earlier history did not request a source page');})]);
+    assert.equal(await longDialogue.count(),1,'An interrupted page keeps the saved conversation visible');
+    await page.screenshot({path:resolve(outputDir,'attached-history-interrupted-desktop.png'),animations:'disabled'});
+    await page.setViewportSize({width:390,height:844});
+    await page.screenshot({path:resolve(outputDir,'attached-history-interrupted-narrow.png'),animations:'disabled'});
+    await page.setViewportSize({width:1512,height:982});
+    await Promise.race([pagingStarted, page.waitForTimeout(4_000).then(() => {throw new Error('An interrupted response with successful headers did not automatically resume history');})]);
+    assert.ok(olderReads[0].every(Boolean),'The request identifies the original history and position');
+    assert.deepEqual(olderReads[1],olderReads[0],'Automatic recovery retries the same source and position');
     await longDialogue.locator('p').first().click();
     const summaryTop = (await workSummary.boundingBox()).y;
     releasePage();
     await work.getByText('Saved output 110',{exact:true}).waitFor({state:'attached'});
     await panel.getByRole('alert').waitFor({state:'hidden'});
     assert.ok(Math.abs((await workSummary.boundingBox()).y - summaryTop) < 2,'Prepending a page keeps the source summary at the same reading position');
+    await page.screenshot({path:resolve(outputDir,'attached-history-recovered-desktop.png'),animations:'disabled'});
+    await page.setViewportSize({width:390,height:844});
+    await page.screenshot({path:resolve(outputDir,'attached-history-recovered-narrow.png'),animations:'disabled'});
+    await page.setViewportSize({width:1512,height:982});
     await page.unroute('**/api/chat/codex-attached?*',holdHistory);
     await workSummary.focus(); await page.keyboard.press('Enter');
     const expandedGroup = await work.elementHandle();

examples/personal-workspace-browser/codex_attached_fixture.py

@@ -8,6 +8,7 @@
 import tempfile
 import threading
 import time
+from urllib.parse import parse_qs, urlsplit
 
 from contextlib import ExitStack
 from types import SimpleNamespace
@@ -90,18 +91,30 @@ def do_GET(self):
                 elif (
                     body_fault
                     and self.path.startswith("/api/chat/codex-attached?")
-                    and "agent_id=" not in self.path
+                    and (
+                        "before" in parse_qs(urlsplit(self.path).query)
+                        if body_fault == "history"
+                        else "agent_id" not in parse_qs(urlsplit(self.path).query)
+                    )
                 ):
-                    # Headers first, then a body that never completes: the client
-                    # read limit aborts a stalled body, and a short close against
-                    # the declared length surfaces as a network error. Both keep
-                    # the status the response already carried.
+                    # Send actual headers, then end the connection short of the
+                    # declared body length (or let the browser's read time out).
                     mode, body_fault = body_fault, None
-                    self.send_response(503 if mode == "timeout" else 403)
-                    self.send_header("Content-Type", "text/html; charset=utf-8")
+                    status = {"timeout": 503, "drop": 403, "history": 200}[mode]
+                    self.send_response(status)
+                    self.send_header(
+                        "Content-Type",
+                        "application/json"
+                        if status == 200
+                        else "text/html; charset=utf-8",
+                    )
                     self.send_header("Content-Length", "200")
                     self.end_headers()
-                    self.wfile.write(b"<html><body>Service unavailable")
+                    self.wfile.write(
+                        b'{"ok":'
+                        if status == 200
+                        else b"<html><body>Service unavailable"
+                    )
                     self.wfile.flush()
                     if mode == "timeout":
                         time.sleep(7.5)
@@ -121,11 +134,13 @@ def do_POST(self):
                     )
                     self._send_json({"ok": True})
                     return
-                if self.path in {
-                    "/fixture/discovery-body-timeout",
-                    "/fixture/discovery-body-drop",
-                }:
-                    body_fault = "timeout" if self.path.endswith("timeout") else "drop"
+                faults = {
+                    "/fixture/discovery-body-timeout": "timeout",
+                    "/fixture/discovery-body-drop": "drop",
+                    "/fixture/history-body-drop": "history",
+                }
+                if self.path in faults:
+                    body_fault = faults[self.path]
                     self._send_json({"ok": True})
                     return
                 if self.path == "/fixture/work-records":