diff --git a/Resources/bin/cmux-claude-wrapper b/Resources/bin/cmux-claude-wrapper
index 1cd5d09487bd..419544a576d0 100755
--- a/Resources/bin/cmux-claude-wrapper
+++ b/Resources/bin/cmux-claude-wrapper
@@ -885,7 +885,11 @@ install_cmux_node_options
 # - preferredNotifChannel: disables Claude Code's OSC/terminal notification
 #   channel inside cmux so hooks are the only notification source.
 # - SessionStart/Stop/Notification: existing lifecycle hooks
-# - SessionEnd: cleanup when Claude exits (covers Ctrl+C where Stop doesn't fire)
+# - SessionEnd: cleanup when Claude exits (covers Ctrl+C where Stop doesn't fire).
+#   Synchronous (not async) so cleanup completes before Claude tears down, with
+#   the same 10s budget as the other synchronous hooks. A 1s timeout was too
+#   tight: cold-starting the cmux binary at teardown routinely exceeds it, so
+#   Claude Code cancels the hook ("Hook cancelled") before cleanup runs (#8637).
 # - UserPromptSubmit: clears "Needs input" and sets "Running" on new prompt
 # - PreToolUse: rejects unsupported durable cron requests synchronously, then
 #   (async) clears "Needs input" / sets "Running" for ordinary tools, and flags
@@ -912,7 +916,7 @@ install_cmux_node_options
 #   timeout because it may run a summarization subprocess; it gates itself
 #   on the workspaceAutoNaming setting via a socket probe, so it is a
 #   no-op when the feature is disabled.
-HOOKS_JSON='{"preferredNotifChannel":"notifications_disabled","hooks":{"SessionStart":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude session-start","timeout":10}]}],"Stop":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude stop","timeout":10}]},{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks feed --source claude","timeout":10,"async":true}]},{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude auto-name","timeout":120,"async":true}]}],"SubagentStop":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks feed --source claude","timeout":10,"async":true}]}],"SessionEnd":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude session-end","timeout":1}]}],"Notification":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude notification","timeout":10}]}],"UserPromptSubmit":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude prompt-submit","timeout":10}]}],"PreToolUse":[{"matcher":"CronCreate","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude cron-create-guard","timeout":5}]},{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude pre-tool-use","timeout":5,"async":true}]}],"PostToolUse":[{"matcher":"PushNotification","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude push-notification","timeout":10,"async":true}]}],"PermissionRequest":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks feed --source claude","timeout":125}]}]}}'
+HOOKS_JSON='{"preferredNotifChannel":"notifications_disabled","hooks":{"SessionStart":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude session-start","timeout":10}]}],"Stop":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude stop","timeout":10}]},{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks feed --source claude","timeout":10,"async":true}]},{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude auto-name","timeout":120,"async":true}]}],"SubagentStop":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks feed --source claude","timeout":10,"async":true}]}],"SessionEnd":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude session-end","timeout":10}]}],"Notification":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude notification","timeout":10}]}],"UserPromptSubmit":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude prompt-submit","timeout":10}]}],"PreToolUse":[{"matcher":"CronCreate","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude cron-create-guard","timeout":5}]},{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude pre-tool-use","timeout":5,"async":true}]}],"PostToolUse":[{"matcher":"PushNotification","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks claude push-notification","timeout":10,"async":true}]}],"PermissionRequest":[{"matcher":"","hooks":[{"type":"command","command":"\"${CMUX_CLAUDE_HOOK_CMUX_BIN:-cmux}\" hooks feed --source claude","timeout":125}]}]}}'
 
 # Fold any user-provided --settings into HOOKS_JSON before launching.
 #