Closes#1866.
Model Catalogue → Engines showed "Engine unavailable. Check installation and
configuration." and "Last error: A previous engine check failed." for engines
the user had simply never installed. Neither names a missing package, a missing
step, or a next action, and the second reads like a crash or a poisoned cache
rather than "you have not installed this yet" — so a normal, expected state
looked like a fault.
The probe's own sentence still cannot cross the boundary: it carries exception
text, local paths and sometimes credentials, which is why it was replaced in
the first place. What changed is that the private diagnostic is now CLASSIFIED
into a VoiceStudio-owned category — package not installed, needs configuring,
file missing or unreadable — exactly the shape _public_routing_reason already
uses for routing. Anything unrecognised keeps the old generic sentence rather
than asserting a cause the probe never gave.
test_docs_url_survives_the_public_metadata_scrub pinned the generic wording
while testing something else; it now asserts what it is actually about, that no
private text survives.
Also skips the exec-bit placeholder test on Windows, where os.access(X_OK) is
true for any existing file so the assertion cannot fail — it errored the whole
module on a Windows checkout. Pre-existing, unrelated to this change, and in
the way of running these tests at all.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017ypcgSsh5j2PEonSJiAU1S
