Tirith ships no Windows binary, so on every Windows CLI startup users
saw a scary 'tirith security scanner enabled but not available' banner
they could not act on. The banner suggested degraded security; in
reality pattern-matching guards still run and the message was pure noise.
Fix:
- New public is_platform_supported() helper in tools/tirith_security.py
that returns False when _detect_target() doesn't resolve (Windows, any
non-x86_64/aarch64 arch).
- ensure_installed(), _resolve_tirith_path(), and check_command_security()
short-circuit on unsupported platforms: cache _resolved_path =
_INSTALL_FAILED with reason 'unsupported_platform', skip PATH probes,
skip the background download thread, skip the disk failure marker, and
return allow with an empty summary from check_command_security so the
spawn loop never fires.
- Explicit user-configured tirith_path is still honored everywhere (a
user who built tirith themselves under WSL keeps that path).
- CLI banner in cli.py gated on is_platform_supported() — fires only on
platforms where tirith *should* work but isn't installed.
- Docs note tirith's supported-platform list and point Windows users at
WSL.
Tests: tests/tools/test_tirith_security.py +8 tests covering Linux
x86_64, Darwin arm64, Windows, and unknown-arch verdicts plus the
silent ensure_installed / check_command_security / _resolve_tirith_path
fast-paths and the explicit-path override.
test_tirith_security.py 75 passed (8 new + 67 pre-existing)
test_command_guards.py 19 passed
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