Adds a real activation-capability probe so a downstream install-ordering
guard (C2, out of scope here) can refuse to wire lease-broker enforcement
(PreToolUse/Stop hooks) on a host that cannot actually activate it — the
root cause of #828's version-skew brick, where the published CLI tarball
lagged the enforcement reseed and every tool call denied with
GATE_UNAVAILABLE.
- LEASE_ACTIVATION_CAPABILITY {name, version}: versioned signal owned by
the activation half (execLeaseGatedRuntime), independent of npm semver.
- Hidden `mosaic __lease-capability` subcommand: prints that capability
from the actually-resolvable built CLI artifact, not source-tree
presence.
- leaseEnforcementActivatable(): pure predicate, true iff a compatible
capability is advertised AND the broker supervisor (launcher + daemon.py
artifacts, socket path) resolves. Detection only — never starts the
broker. Both inputs are injectable for testing.
- C-REGRESS: added a vitest spec that runs the two test-locked fail-closed
gate cases in runtime_tools_unittest.py directly, proving the gate's
fail-closed-on-absent-identity behavior is unchanged by this card.
Part of #869 (Point-1 C1).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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