fix: extend daemon proxy read timeout

[buiilding]

Summary

Fixes #1864.

This PR fixes the MCP -> daemon proxy timeout described in the issue. It does not make get_window_state smaller or bypass AX traversal; it makes the daemon transport wait long enough for legitimate tool execution and return a clearer transport timeout if the daemon still does not respond.

Issue Behavior Addressed

The issue reports that this path can fail:

MCP client -> cua-driver mcp stdio server -> cua-driver serve daemon over Unix socket -> get_window_state

The same get_window_state operation can look healthy through cua-driver call, while the MCP proxy path fails with:

Resource temporarily unavailable (os error 35)

The root cause fixed here is the proxy client read timeout: send_request used a hardcoded 10-second socket read timeout. Slow but valid daemon calls, especially get_window_state, could exceed that transport timeout before the tool returned its own result or timeout. On macOS, that timed-out socket read appears as WouldBlock / EAGAIN / os error 35.

What Changed

• Replaced the inline daemon socket timeout with named daemon write/read timeout constants.
• Raised the daemon read timeout from 10 seconds to 60 seconds.
• Kept the write timeout short at 5 seconds.
• Mapped WouldBlock / TimedOut while reading the daemon response into a clear error:

daemon timed out waiting for response after 60s

The 60-second transport budget is intentionally above the macOS get_window_state AX walk timeout of 30 seconds, leaving room for screenshot capture, resizing/encoding or screenshot_out_file, and JSON response serialization.

This PR intentionally does not blindly retry on EAGAIN. In this code path, EAGAIN is the socket read timeout firing, not a transient readiness event from a nonblocking socket loop. Retrying would hide the timeout policy instead of fixing the proxy deadline.

Relation To The Issue's Upstream Questions

Resolved by this PR:

• os error 35 / EAGAIN in the MCP -> daemon proxy no longer leaks as the primary failure for slow-but-valid daemon responses below the transport budget.
• The proxy now waits longer than the old 10-second transport timeout and longer than the macOS get_window_state AX timeout.
• If the daemon still does not respond inside the transport budget, the user gets a daemon timeout message instead of raw macOS EAGAIN.

Not changed by this PR and still follow-up scope:

• Whether screenshot_out_file should be the recommended long-term payload-size strategy.
• Whether large screenshot payloads should default to files or be chunked.
• Whether Apple Notes empty/unusable AX trees are a known platform limitation or need an alternate traversal path.
• Coordinate click semantics on HiDPI displays, including whether coordinate click should accept window_id for multi-window disambiguation.
• Idle CPU around 52-54% in the driver process.
• Whether the removed screenshot tool is intentionally replaced by get_window_state(capture_mode=vision).

screenshot_out_file remains useful as an optional payload-size mitigation, but it is not the primary fix for this bug. The transport timeout/backpressure behavior is the bug addressed here.

Validation

• cargo test -p cua-driver daemon_response_read_tests
• git diff --check
• local install-local.sh rebuild and CuaDriver daemon restart
• forced MCP proxy reproduction with a fake daemon delaying get_window_state for 12 seconds; the call succeeds instead of failing at the old ~10-second transport timeout

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[injaneity]

closed as superseded by #1997