From cea9d42fcc330be33a1df5d7dfa31820f636800a Mon Sep 17 00:00:00 2001
From: ai-ag2026 <261867348+ai-ag2026@users.noreply.github.com>
Date: Sat, 13 Jun 2026 22:02:07 +0200
Subject: [PATCH] fix: extend timeout for full history session loads

(cherry picked from commit 27cbff974eeaa58780d91fb4f25802cf0ac76381)
---
 CHANGELOG.md                                       |  4 ++++
 static/sessions.js                                 |  2 +-
 ...test_issue2184_fork_from_here_absolute_index.py | 14 ++++++++++++++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index aa691231..a558a6ae 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- **Full-history session loads now use an extended client timeout.** Actions that intentionally fetch the entire transcript (fork/export/start-jump helpers) can legitimately take longer than the default API timeout on very large sessions; the WebUI now gives that path up to 120 seconds instead of showing a premature "Request timed out" toast while the backend is still working.
+
 ## [v0.51.395] — 2026-06-13 — Release NH (push source filters into agent session scans, #3930)
 
 ### Fixed
diff --git a/static/sessions.js b/static/sessions.js
index d944d497..2341c94a 100644
--- a/static/sessions.js
+++ b/static/sessions.js
@@ -2470,7 +2470,7 @@ async function _ensureAllMessagesLoaded() {
   _loadingOlder = true;
   try {
     const sid = S.session.session_id;
-    const data = await api(`/api/session?session_id=${encodeURIComponent(sid)}&messages=1&resolve_model=0`);
+    const data = await api(`/api/session?session_id=${encodeURIComponent(sid)}&messages=1&resolve_model=0`, {timeoutMs:120000});
     // Guard: api() may have redirected (401) and returned undefined.
     if (!data || !data.session) return;
     // Session may have been switched while we awaited. Bail rather than
diff --git a/tests/test_issue2184_fork_from_here_absolute_index.py b/tests/test_issue2184_fork_from_here_absolute_index.py
index a4e23ef9..05fa2192 100644
--- a/tests/test_issue2184_fork_from_here_absolute_index.py
+++ b/tests/test_issue2184_fork_from_here_absolute_index.py
@@ -160,6 +160,20 @@ def test_ensure_all_resets_oldest_idx_to_zero():
     )
 
 
+def test_ensure_all_messages_uses_extended_timeout_for_full_history_load():
+    """Full-history loads for fork/export/start-jump can legitimately exceed the API default timeout."""
+    body = _function_body(SESSIONS_JS, "_ensureAllMessagesLoaded")
+    full_history_call = re.search(
+        r"api\((?P<url>`[^`]*messages=1&resolve_model=0[^`]*`)\s*,\s*\{(?P<opts>[^}]*)\}\s*\)",
+        body,
+        re.S,
+    )
+    assert full_history_call, "_ensureAllMessagesLoaded must pass options to the full-history api() call"
+    timeout_match = re.search(r"timeoutMs\s*:\s*(\d+)", full_history_call.group("opts"))
+    assert timeout_match, "Full-history api() call must specify timeoutMs"
+    assert int(timeout_match.group(1)) >= 120000
+
+
 # ---------------------------------------------------------------------------
 # Short-session / full-transcript behaviour preserved
 # ---------------------------------------------------------------------------