fix(#829): gate claudex and close branch coverage gaps

docs/architecture/lease-broker-security.md

@@ -6,7 +6,7 @@
 - Session IDs and cycle tokens use the OS cryptographic RNG. `Math.random` and model output are not token sources.
 - Framing and persistence failures fail closed. Sensitive tokens are not logged.
 - Built-in `0700`/`0600` filesystem modes provide same-principal hardening only, not socket authenticity against the same UID. WI-1 provides no distinct-principal isolation. That stronger deployment requires an external protected proxy, ACL, or service boundary, and the boundary must preserve authenticated client identity for the broker's `SO_PEERCRED` and ancestry authorization rather than substituting a shared proxy identity.
-- WI-2 whole-class authorization denies every consequential, unknown, and custom tool while UNVERIFIED; it does not inspect shell strings or trust wrapper selection.
+- WI-2 whole-class authorization denies every consequential, unknown, and custom tool while UNVERIFIED; it does not inspect shell strings or trust wrapper selection. First-class Claude/Pi and both Claudex dispatch modes use broker register-before-exec; Claudex additionally installs the mandatory all-tools hook inside its preserved isolated config and fails closed on unsafe settings.
 - WI-2 promotion consumes a WI-1 cycle token before VERIFIED becomes visible. Observer revocation, runtime-generation replacement, broker restart, and monotonic TTL expiry remove authority.
 - Receipt observation, payload construction, compaction observers, and constrained recovery implementation remain later surfaces. A receipt can become a promotion prerequisite but is never the safety mechanism.
 

docs/architecture/mutator-class-gate.md

@@ -1,6 +1,6 @@
 # Whole mutator-class lease gate
 
-WI-2 adds the framework-native authorization boundary for Claude and Pi. Every runtime-reported tool name reaches the lease broker before execution. The gate classifies capabilities by the whole tool class; it never parses a Bash command to decide whether that particular string looks read-only.
+WI-2 adds the framework-native authorization boundary for Claude (including the supported Claudex overlay) and Pi. Every runtime-reported tool name reaches the lease broker before execution. The gate classifies capabilities by the whole tool class; it never parses a Bash command to decide whether that particular string looks read-only.
 
 ## Default-deny policy
 
@@ -30,6 +30,7 @@ A receipt is only a future promotion prerequisite. It is not an obedience, resid
 `launch-runtime.py` registers itself with the broker and then `exec`s Claude or Pi so PID/starttime remain the authenticated parent anchor. It exports only the broker-minted session ID and current generation to descendants.
 
 - Claude installs `mutator-gate.py` as an all-tools (`.*`) `PreToolUse` hook.
+- `mosaic claudex` and `mosaic yolo claudex` preserve their isolated `CLAUDE_CONFIG_DIR`, merge the mandatory hook into that isolated `settings.json`, and use the same register-before-exec launcher. Malformed or symlinked isolated settings deny launch.
 - Pi invokes the same executable from its `tool_call` handler.
 
 The executable submits the runtime's actual tool name to `authorize_tool`. Missing identity, malformed input/reply, timeout, broker unavailability, or denial exits with status 2 and blocks fail-closed.