feat(fleet): add shared role semantics

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/fleet/reference/roster-v2-fields.md

@@ -81,6 +81,35 @@ agents:
 | `agents[].lifecycle.desired_state`                   | yes      | `running` or `stopped`                                                                               |
 | `agents[].launch.yolo`                               | yes      | boolean; structured data only, not an arbitrary command escape hatch                                 |
 
+## Semantic handoff
+
+`parseRosterV2` and `normalizeRosterV2` remain synchronous and structural. After structural success,
+call the asynchronous `validateRosterV2Semantics` handoff before using persona identity or authority.
+That validator batches the baseline `fleet/roles/` and operator `fleet/roles.local/` scans, then
+delegates every agent to the shared persona resolver.
+
+Semantic validation:
+
+- requires the winning role contract to be readable and non-empty; `LIBRARY.md` membership alone does
+  not resolve a class;
+- retains `requestedClass` separately from `canonicalClass` in typed output;
+- canonicalizes only `implementer` to `code`, `reviewer` to `review`, and
+  `operator-interaction` to `interaction`;
+- canonicalizes `tool_policy` with the same exact alias table;
+- rejects protected class/tool-policy mismatches in either direction, while accepting
+  `class: operator-interaction` with `tool_policy: operator-interaction` as canonical
+  `interaction`;
+- derives immutable protected authority only from canonical class; and
+- accepts custom baseline or `roles.local` classes without granting protected authority.
+
+`agents[].alias` remains display-only. Tess and Ultron are instance names, never semantic classes.
+Canonicalization happens before role-layer lookup, so a legacy-named override cannot redefine an
+alias as separate authority. See [Role Classes and Authority](./role-classes.md) and
+[Customize Fleet Roles](../how-to/customize-roles.md).
+
+This handoff performs no filesystem, systemd, tmux, roster, credential, lease, certificate, or
+lifecycle mutation.
+
 ## Fail-closed boundary
 
 Every object is `additionalProperties: false`. The compiler rejects unknown, missing, malformed,