The first fix handled the EAGAIN McpError path. But the persistent MCP
session (long-running gateway/desktop worker) has a second failure mode:
list_windows or get_window_state 'succeed' over MCP yet return a
degenerate/empty payload (no windows, or no screenshot + blank tree)
WITHOUT raising — typically when the bridge reconnected mid-call and
dropped the heavy response. That surfaced to the model as a silent 0x0
capture with no error and no fallback firing (0.00s empty return).
Fix: detect empty results in capture() and re-fetch over the CLI
transport before giving up:
- empty list_windows -> CLI re-fetch the window list
- empty get_window_state (som/ax) -> CLI re-fetch the AX tree + screenshot
- empty screenshot (vision) -> CLI re-fetch get_window_state for the PNG
Adds 2 regression tests. Full suite: 83 passed.
Adrian Lastra
13b75e73ff