# Fleet Identity, Class, and Runtime

Each roster field has one job. Do not use names or model strings as authority shortcuts.

| Concern                 | Field                           | Contract                                                                                     |
| ----------------------- | ------------------------------- | -------------------------------------------------------------------------------------------- |
| Stable machine identity | `agents[].name`                 | Unique, immutable mutation target and exact service/session name.                            |
| Display identity        | `agents[].alias`                | Human-facing label only; may be changed and grants no authority.                             |
| Behavioral contract     | `agents[].class`                | Resolves through the shared baseline plus `roles.local` persona library.                     |
| Tool boundary           | `agents[].tool_policy`          | Must match protected canonical classes; cannot independently grant authority.                |
| Harness                 | `agents[].runtime`              | One of `claude`, `codex`, `opencode`, or `pi`, declared in `runtimes`.                       |
| Backend selection       | `agents[].provider` and `model` | Explicit non-empty data; capability validity is not inferred from the display name or class. |
| Effort                  | `agents[].reasoning`            | `low`, `medium`, or `high`.                                                                  |
| Local placement         | `working_directory`             | Explicit safe local work path; not remote placement authority.                               |

Tess and Ultron are conventional instance/display names only. They are not products, required machine identities, role aliases, or authority-bearing classes. A configurable interaction instance uses `class: interaction`; a configurable validation instance uses `class: validator`. Any stable name and alias satisfying the structural contract may be used.

Class aliases are deliberately narrow: `implementer → code`, `reviewer → review`, and `operator-interaction → interaction`. No runtime, provider, model, persona prose, or instance name changes this mapping. See [role classes](../reference/role-classes.md) and the [validated generic example](../examples/roster-v2.yaml).

Roster v2 is local-only. It contains no host/SSH placement, connector, channel, secret-reference, arbitrary-command, per-agent socket, or gateway mapping fields. Those concerns require separate requirements and threat models.