fix(#1264): harden unattended identity bootstrap

docs/USER-GUIDE/workflows/fleet-unattended-first-start.md

@@ -11,7 +11,8 @@ stop at the interactive identity wizard.
 When `MOSAIC_AGENT_NAME` names an exact member of the installed fleet roster and top-level identity
 contracts are absent, the launcher:
 
-1. validates the exact roster member and installed fleet communications helper;
+1. validates the exact roster member, its canonical class, and the installed fleet communications
+   helper;
 2. reads the shipped generic contracts from
    `~/.config/mosaic/defaults/SOUL.md` and `defaults/USER.md`;
 3. creates only the missing top-level `SOUL.md` and `USER.md` as owner-private files;
@@ -37,9 +38,10 @@ A roster-owned seat may be started without attaching to its pane:
 mosaic fleet start <exact-roster-name>
 ```
 
-Mosaic refuses before runtime execution if the requested member is absent, a required default is
-missing or unsafe, or an existing identity contract is not a safe regular file. Repair the named
-path and retry the same exact roster member; do not copy another seat's personalized identity.
+Mosaic refuses before runtime execution if the requested member is absent, its ambient class
+conflicts with the roster, a required default is missing or unsafe, or an existing identity contract
+is not a safe regular file. Repair the named component and retry the same exact roster member; do not
+copy another seat's personalized identity.
 
 ## Separate prerequisites