feat(fleet): add shared role semantics (#768)

docs/fleet/reference/role-classes.md

@@ -0,0 +1,45 @@
+# Fleet Role Classes and Authority
+
+A fleet role class is a machine identity resolved from the persona library. Resolution uses the
+canonical class before consulting the baseline `fleet/roles/` and operator `fleet/roles.local/`
+layers. A readable role contract is required; an index entry alone is not semantic success.
+
+## Canonicalization
+
+Only these legacy class aliases are recognized:
+
+| Requested class        | Canonical class |
+| ---------------------- | --------------- |
+| `implementer`          | `code`          |
+| `reviewer`             | `review`        |
+| `operator-interaction` | `interaction`   |
+
+No other alias is inferred. In particular, `worker`, `analyst`, and `canary` are custom classes only
+when an operator supplies a readable contract for that exact class. Tess and Ultron are instance
+names, not classes. `agents[].alias` is display-only and cannot grant authority.
+
+Canonicalization happens before role lookup. For example, requesting `implementer` resolves
+`code.md`; a separate `roles.local/implementer.md` cannot redefine the legacy alias. A canonical
+`roles.local/code.md` still overrides the baseline `roles/code.md` contract.
+
+## Protected authority
+
+Protected authority is immutable metadata derived only from canonical class. Role prose, instance
+name, display alias, tool policy, runtime, and custom role files cannot grant it.
+
+| Canonical class   | Granted authority                                  | Explicit limits                                                                   |
+| ----------------- | -------------------------------------------------- | --------------------------------------------------------------------------------- |
+| `merge-gate`      | Sole approve-to-land and merge authority           | No authority is inferred by similarly named custom roles or policies.             |
+| `validator`       | May issue a validation certificate                 | Cannot approve-to-land or merge.                                                  |
+| `orchestrator`    | May orchestrate, manage topology, and issue leases | Cannot approve-to-land or merge.                                                  |
+| `team-leader`     | May use orchestrator-leased capacity               | Cannot issue leases or mutate roster, configuration, credentials, or merge state. |
+| `interaction`     | Request and status surface                         | Cannot orchestrate, issue leases, mutate roster/configuration, or merge.          |
+| all other classes | No protected authority implicitly                  | Custom contracts do not acquire protected powers from prose.                      |
+
+Roster-v2 semantic validation requires a protected class and its canonical tool policy to match. It
+also rejects an unprotected class paired with a protected tool policy. The legacy tool-policy name
+`operator-interaction` canonicalizes to `interaction`.
+
+This mapping describes authority metadata only. Lease issuance, validation-certificate storage or
+workflow, lifecycle reconciliation, credentials, roster mutation, and merge execution are outside
+this resolver contract.

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,