[dimonp]

Flush the X connection following XRecordCreateContext so the record context is fully registered before the event tap starts.

Error log:
robot-cpp/build/bin$ ./example_record_replay
Recording for 5 seconds...
X Error of failed request: XRecordBadContext
Major opcode of failed request: 143 (RECORD)
Minor opcode of failed request: 5 (XRecordEnableContext)
Context in failed request: 0x8c00001
Serial number of failed request: 10
Current serial number in output stream: 10

References:

• Xlib: XSync Documentation — Explains how XSync flushes the output buffer and waits until all requests have been processed.
• X Record Extension Specification — Details the asynchronous nature of context creation and resource allocation.

[developer239]

Thank you @dimonp, and welcome as the first outside contributor to robot-cpp! 🎉

Good catch, and a clear write-up. XRecordCreateContext only queues the request on the control connection, while XRecordEnableContext goes out on the separate data connection, so the server could see the enable before the context existed. XSync on the control connection closes that race. I updated the branch from master so CI ran against the current code, and it passed on Linux, macOS and Windows. Merging, and it will ship in the next robot-ts release.