The `readDenyPaths` policy field shipped in the previous commit broke Linux
confinement outright. bwrap has to create the `/dev/null` bind's mount point
inside a tree its own profile has already made read-only, so it refused the
entire confinement whenever the parent directory was absent — every host that
has not stored a credential yet, including a fresh install:
bwrap: Can't mkdir parents for /home/runner/.dsh/.env: Read-only file system
which the executor correctly classifies as SANDBOX_UNAVAILABLE, so every
confined bash call failed closed. Landlock cannot subtract from its own `/`
read grant, so it reported `partial` enforcement on every confined call for a
file it never hid, with no way to switch the denial off (schemastery fills an
omitted array with `[]`, so empty and omitted were indistinguishable).
A protection that breaks confinement where it works and misreports it where it
does not is worse than a documented absence. Revert the field, both expressible
backends, the enforcement downgrade, and the policy default; state the residue
plainly in the credentials-local READMEs — file mode stops other OS users, not
the model — and keep the OS-keychain provider recorded as the real answer.
The narrower discipline stands: no surface hoists the credential document into
`process.env`, and the model is never handed a resolved path to it.