Origin: Surfaced when the Windows CI matrix entries (added in PR #639 closing #637) ran for the first time. 6 tests in tests/test_cli.py::TestStdinInput::* fail on Windows with Error: file not found: /dev/stdin.

The pattern

Vera's CLI supports vera <subcommand> /dev/stdin as a way to read source from stdin (an alternative to the - convention used by some other CLIs). /dev/stdin is a Unix-specific path — Windows doesn't have it.

Failing tests:

• test_check_reads_source_once
• test_run_dev_stdin_subprocess
• test_verify_dev_stdin_subprocess
• test_compile_dev_stdin_wat
• test_compile_dev_stdin_default_output
• test_check_dev_stdin_module_resolution

All hit the same shape:

CompletedProcess(args=['python.exe', '-m', 'vera.cli', 'check', '/dev/stdin'],
                 returncode=1, stderr='Error: file not found: /dev/stdin\n')

Recommended fix

Two parts:

1. CLI: add Windows-compatible stdin handling. Either (a) special-case - as a stdin sentinel (Unix convention), (b) detect /dev/stdin on Windows and silently route to sys.stdin, or (c) add a dedicated --stdin flag. Option (a) is most idiomatic across CLI tools; option (b) is most backward-compatible (existing /dev/stdin users on Unix keep working, Windows just learns to handle it).

2. Tests: parametrize over the stdin sentinel. tests/test_cli.py::TestStdinInput should test both /dev/stdin (Unix) and whichever sentinel is chosen for Windows (- or whatever). On Windows, the /dev/stdin parameterisation should pytest.skip("Unix-only").

Out of scope

• Renaming or deprecating /dev/stdin support on Unix. Keep it for backward compatibility.
• Other Unix-only paths in the CLI (e.g. /dev/null). If they show up as Windows test failures, file separately.

Acceptance criteria

• All 6 tests in tests/test_cli.py::TestStdinInput pass on windows-latest, 3.{11,12,13} after the fix.
• Existing /dev/stdin invocations on Unix continue to work.

Pairs with

• Add windows-latest to CI test matrix (3 runners mirroring Ubuntu / macOS) #637 — Windows CI matrix expansion. This issue is one of three blockers on dropping Add windows-latest to CI test matrix (3 runners mirroring Ubuntu / macOS) #637's advisory mode.
• #? — cp1252 encoding audit (sibling Windows-compatibility issue).
• #? — \U escape investigation.