The C1 credential-hygiene fix converted InitializeAsync and ReadAsync to
surface only ex.GetType().Name, but left HandlePollError building its
operator-facing Degrade() message from raw ex.Message, gated only by
'if (ex is DbException) return;'. That guard exists for the I1
double-classification concern, not for message safety, and it is incomplete
for the leak vector: a malformed connection string throws ArgumentException
from the keyword parser (the same unquoted-';'-in-password shape the sibling
SqlDriverBrowser.Sanitize special-cases), which is not a DbException and so
reaches Degrade(ex.Message) unredacted.
It is unreachable in today's control flow only because the connection string
is static and validated identically at Initialize first — an emergent
property, not an enforced invariant, and a live per-poll leak the moment a
future edit (refresh-on-reinit, a different provider) breaks that assumption.
Make the fallback type-only like the other two sites; the full exception still
reaches the log sink via the exception parameter. The I1 defer + control tests
are unaffected (they assert Degraded, not message text). Pinned by a new test
driving a credential-bearing ArgumentException through HandlePollError;
verified load-bearing (red against Degrade(ex.Message), green after).
Closes the C1 review finding on commit 37f444b9.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Joseph Doherty
585f827ef3