From a28e13b6e647a999bace538bf52b8596d2822018 Mon Sep 17 00:00:00 2001
From: teknium1 <127238744+teknium1@users.noreply.github.com>
Date: Wed, 23 Sep 2026 03:55:48 -0700
Subject: [PATCH] fix(tui_gateway): bind the session cwd around manual
 /compress

session.compress runs compress_now on the RPC thread without the session context, so the
compaction-boundary system-prompt rebuild resolved the backend's cwd (the process HOME) and
persisted a prompt whose cwd line every later process rejects as stale runtime. The next
resume (TUI or 'hermes chat --resume') then rebuilt the prompt from scratch - a second
prompt-cache miss right after the sanctioned compaction one - and, on the oneshot path,
skipped the tools pin. Bind the session cwd exactly like the sibling prompt-persist sites
(server.py _persist_live_session_system_prompt, methods_slash.py).

Exposed by tests/e2e/core/history/test_prefix_stability.py[tui_gateway_restarts].
---
 tui_gateway/session_compression.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tui_gateway/session_compression.py b/tui_gateway/session_compression.py
index 05d5b8ad36..e2e6f54975 100644
--- a/tui_gateway/session_compression.py
+++ b/tui_gateway/session_compression.py
@@ -242,7 +242,13 @@ def _compress_session_history(
     request = parse_compress_args(focus_topic or "")
     if request.aggressive:
         raise ValueError(AGGRESSIVE_UNSUPPORTED)
-    result = compress_now(agent, before_messages, request, task_id=session.get("session_key") or "default")
+    # RPC thread: bind the session cwd, or the boundary prompt rebuild resolves the backend's cwd and
+    # persists a prompt every other process then rejects as stale runtime (fresh build, no tools pin).
+    tokens = _set_session_context(session.get("session_key") or "", cwd=_session_cwd(session))
+    try:
+        result = compress_now(agent, before_messages, request, task_id=session.get("session_key") or "default")
+    finally:
+        _clear_session_context(tokens)
     if result.status == "preview":
         return 0, _get_usage(agent)
     # Lock-skipped: raise so callers surface a clear message instead of "No changes from compression".