feat(fleet): add roster v2 structural compiler

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

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+# Fleet Roster v2 Structural Contract
+
+**Status:** FCM-M1-001 local-tmux structural compiler contract. This document describes parsing,
+strict structural validation, normalized in-memory representation, and deterministic rendering only.
+It does not authorize role resolution, lifecycle reconciliation, mutation, migration, remote
+placement, connector configuration, secret references, arbitrary commands, channels, gateway
+mapping, or any live-fleet change.
+
+The executable schema is [`roster-v2.schema.json`](./roster-v2.schema.json). The compiler exports
+the same schema and its test parses this file and compares it structurally with the executable contract.
+
+## Format and canonical shape
+
+The compiler accepts YAML or JSON. It reads only snake_case source fields and renders canonical,
+snake_case YAML. Rendering sorts runtime keys and agents by stable name. Agent names, class names,
+and tool-policy names are structural identifiers; whether a class or policy resolves is a later
+shared-resolver concern.
+
+```yaml
+version: 2
+generation: 1
+transport: tmux
+tmux:
+  socket_name: mosaic-fleet
+  holder_session: _holder
+defaults:
+  working_directory: ~/src
+  runtime: pi
+runtimes:
+  pi:
+    reset_command: /new
+agents:
+  - name: coder0
+    alias: Coder 0
+    class: code
+    runtime: pi
+    provider: openai
+    model: gpt-5.6-sol
+    reasoning: high
+    tool_policy: code
+    working_directory: ~/src
+    persistent_persona: false
+    reset_between_tasks: true
+    lifecycle:
+      enabled: true
+      desired_state: stopped
+    launch:
+      yolo: true
+```
+
+## Root fields
+
+| Field        | Required | Constraint            | Meaning                                                                                                                               |
+| ------------ | -------- | --------------------- | ------------------------------------------------------------------------------------------------------------------------------------- |
+| `version`    | yes      | integer constant `2`  | Identifies this contract. Version `1` is explicitly rejected by this compiler and remains on the existing v1 path until M4 migration. |
+| `generation` | yes      | positive safe integer | Desired-state generation. M2 uses it for mutation guards; M1 does not mutate it.                                                      |
+| `transport`  | yes      | constant `tmux`       | M1–M5 support local tmux only.                                                                                                        |
+| `tmux`       | yes      | strict object         | Explicit local socket and holder-session configuration.                                                                               |
+| `defaults`   | yes      | strict object         | Default work directory and one supported local runtime.                                                                               |
+| `runtimes`   | yes      | non-empty object      | Declared local runtime reset policy map.                                                                                              |
+| `agents`     | yes      | non-empty array       | Local fleet entries. Duplicate stable names are rejected.                                                                             |
+
+## Nested fields
+
+| Path                                                 | Required | Constraint                                                                                           |
+| ---------------------------------------------------- | -------- | ---------------------------------------------------------------------------------------------------- |
+| `tmux.socket_name`                                   | yes      | non-empty `[A-Za-z0-9_.-]+`; an explicit named socket prevents default-versus-named socket ambiguity |
+| `tmux.holder_session`                                | yes      | non-empty `[A-Za-z0-9_.-]+`                                                                          |
+| `defaults.working_directory`                         | yes      | non-empty string                                                                                     |
+| `defaults.runtime`                                   | yes      | `claude`, `codex`, `opencode`, or `pi`; it must be declared in `runtimes`                            |
+| `runtimes.<runtime>.reset_command`                   | yes      | non-empty string; runtime key must be a supported local runtime                                      |
+| `agents[].name`                                      | yes      | unique `[A-Za-z0-9][A-Za-z0-9_.-]*` stable machine identity                                          |
+| `agents[].alias`                                     | yes      | non-empty display string                                                                             |
+| `agents[].class`                                     | yes      | `[a-z][a-z0-9-]*`; structural only in M1, semantic role resolution is FCM-M1-002                     |
+| `agents[].runtime`                                   | yes      | `claude`, `codex`, `opencode`, or `pi`; it must be declared in `runtimes`                            |
+| `agents[].provider`, `model`, `working_directory`    | yes      | non-empty strings; provider/model capability resolution is a later card                              |
+| `agents[].reasoning`                                 | yes      | `low`, `medium`, or `high`                                                                           |
+| `agents[].tool_policy`                               | yes      | `[a-z][a-z0-9-]*`; structural only in M1                                                             |
+| `agents[].persistent_persona`, `reset_between_tasks` | yes      | booleans                                                                                             |
+| `agents[].lifecycle.enabled`                         | yes      | boolean; stored now, reconciled in FCM-M3-001                                                        |
+| `agents[].lifecycle.desired_state`                   | yes      | `running` or `stopped`                                                                               |
+| `agents[].launch.yolo`                               | yes      | boolean; structured data only, not an arbitrary command escape hatch                                 |
+
+## Fail-closed boundary
+
+Every object is `additionalProperties: false`. The compiler rejects unknown, missing, malformed,
+and wrong-type fields before producing a model. It specifically rejects remote/SSH/host/socket
+per-agent fields, connector blocks, secret references, channel fields, arbitrary command fields,
+and gateway fields because they are unsupported in the local-tmux M1 contract. It does not silently
+ignore v1 camelCase input, version `1`, or a source that does not parse to an object.
+
+The v2 compiler is intentionally isolated from the existing v1 loader. Existing v1 rosters and
+current examples/profiles continue on their current path; FCM-M4 owns explicit inventory, preview,
+migration, and rollback. FCM-M2 owns generated-file/local-override quarantine, and FCM-M3 owns
+runtime lifecycle and reconciliation.

docs/fleet/reference/roster-v2.schema.json

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+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://mosaicstack.dev/schemas/fleet/roster-v2.schema.json",
+  "title": "Mosaic local tmux fleet roster v2",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["version", "generation", "transport", "tmux", "defaults", "runtimes", "agents"],
+  "properties": {
+    "version": {
+      "const": 2
+    },
+    "generation": {
+      "type": "integer",
+      "minimum": 1,
+      "maximum": 9007199254740991
+    },
+    "transport": {
+      "const": "tmux"
+    },
+    "tmux": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["socket_name", "holder_session"],
+      "properties": {
+        "socket_name": {
+          "type": "string",
+          "pattern": "^[A-Za-z0-9_.-]+$"
+        },
+        "holder_session": {
+          "type": "string",
+          "pattern": "^[A-Za-z0-9_.-]+$"
+        }
+      }
+    },
+    "defaults": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["working_directory", "runtime"],
+      "properties": {
+        "working_directory": {
+          "type": "string",
+          "minLength": 1
+        },
+        "runtime": {
+          "enum": ["claude", "codex", "opencode", "pi"]
+        }
+      }
+    },
+    "runtimes": {
+      "type": "object",
+      "minProperties": 1,
+      "propertyNames": {
+        "enum": ["claude", "codex", "opencode", "pi"]
+      },
+      "additionalProperties": {
+        "type": "object",
+        "additionalProperties": false,
+        "required": ["reset_command"],
+        "properties": {
+          "reset_command": {
+            "type": "string",
+            "minLength": 1
+          }
+        }
+      }
+    },
+    "agents": {
+      "type": "array",
+      "minItems": 1,
+      "items": {
+        "type": "object",
+        "additionalProperties": false,
+        "required": [
+          "name",
+          "alias",
+          "class",
+          "runtime",
+          "provider",
+          "model",
+          "reasoning",
+          "tool_policy",
+          "working_directory",
+          "persistent_persona",
+          "reset_between_tasks",
+          "lifecycle",
+          "launch"
+        ],
+        "properties": {
+          "name": {
+            "type": "string",
+            "pattern": "^[A-Za-z0-9][A-Za-z0-9_.-]*$"
+          },
+          "alias": {
+            "type": "string",
+            "minLength": 1
+          },
+          "class": {
+            "type": "string",
+            "pattern": "^[a-z][a-z0-9-]*$"
+          },
+          "runtime": {
+            "enum": ["claude", "codex", "opencode", "pi"]
+          },
+          "provider": {
+            "type": "string",
+            "minLength": 1
+          },
+          "model": {
+            "type": "string",
+            "minLength": 1
+          },
+          "reasoning": {
+            "enum": ["low", "medium", "high"]
+          },
+          "tool_policy": {
+            "type": "string",
+            "pattern": "^[a-z][a-z0-9-]*$"
+          },
+          "working_directory": {
+            "type": "string",
+            "minLength": 1
+          },
+          "persistent_persona": {
+            "type": "boolean"
+          },
+          "reset_between_tasks": {
+            "type": "boolean"
+          },
+          "lifecycle": {
+            "type": "object",
+            "additionalProperties": false,
+            "required": ["enabled", "desired_state"],
+            "properties": {
+              "enabled": {
+                "type": "boolean"
+              },
+              "desired_state": {
+                "enum": ["running", "stopped"]
+              }
+            }
+          },
+          "launch": {
+            "type": "object",
+            "additionalProperties": false,
+            "required": ["yolo"],
+            "properties": {
+              "yolo": {
+                "type": "boolean"
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}

packages/mosaic/src/fleet/roster-v2.spec.ts

@@ -0,0 +1,242 @@
+import { readFile } from 'node:fs/promises';
+import { fileURLToPath } from 'node:url';
+import { describe, expect, it } from 'vitest';
+import {
+  ROSTER_V2_JSON_SCHEMA,
+  RosterV2ValidationError,
+  parseRosterV2,
+  renderRosterV2Yaml,
+} from './roster-v2.js';
+
+const validRoster = `
+version: 2
+generation: 7
+transport: tmux
+tmux:
+  socket_name: mosaic-fleet
+  holder_session: _holder
+defaults:
+  working_directory: ~/src
+  runtime: pi
+runtimes:
+  pi:
+    reset_command: /new
+agents:
+  - name: coder0
+    alias: Coder 0
+    class: code
+    runtime: pi
+    provider: openai
+    model: gpt-5.6-sol
+    reasoning: high
+    tool_policy: code
+    working_directory: ~/src
+    persistent_persona: false
+    reset_between_tasks: true
+    lifecycle:
+      enabled: true
+      desired_state: stopped
+    launch:
+      yolo: true
+`;
+
+describe('roster v2 structural compiler', (): void => {
+  it('parses YAML into a normalized typed model and renders canonical YAML', (): void => {
+    const roster = parseRosterV2(validRoster, 'yaml');
+
+    expect(roster).toEqual({
+      version: 2,
+      generation: 7,
+      transport: 'tmux',
+      tmux: { socketName: 'mosaic-fleet', holderSession: '_holder' },
+      defaults: { workingDirectory: '~/src', runtime: 'pi' },
+      runtimes: { pi: { resetCommand: '/new' } },
+      agents: [
+        {
+          name: 'coder0',
+          alias: 'Coder 0',
+          className: 'code',
+          runtime: 'pi',
+          provider: 'openai',
+          model: 'gpt-5.6-sol',
+          reasoning: 'high',
+          toolPolicy: 'code',
+          workingDirectory: '~/src',
+          persistentPersona: false,
+          resetBetweenTasks: true,
+          lifecycle: { enabled: true, desiredState: 'stopped' },
+          launch: { yolo: true },
+        },
+      ],
+    });
+    expect(renderRosterV2Yaml(roster)).toBe(validRoster.trimStart());
+  });
+
+  it('parses JSON and produces the same normalized model', (): void => {
+    const yaml = parseRosterV2(validRoster, 'yaml');
+    const json = JSON.stringify({
+      version: 2,
+      generation: 7,
+      transport: 'tmux',
+      tmux: { socket_name: 'mosaic-fleet', holder_session: '_holder' },
+      defaults: { working_directory: '~/src', runtime: 'pi' },
+      runtimes: { pi: { reset_command: '/new' } },
+      agents: [
+        {
+          name: 'coder0',
+          alias: 'Coder 0',
+          class: 'code',
+          runtime: 'pi',
+          provider: 'openai',
+          model: 'gpt-5.6-sol',
+          reasoning: 'high',
+          tool_policy: 'code',
+          working_directory: '~/src',
+          persistent_persona: false,
+          reset_between_tasks: true,
+          lifecycle: { enabled: true, desired_state: 'stopped' },
+          launch: { yolo: true },
+        },
+      ],
+    });
+
+    expect(parseRosterV2(json, 'json')).toEqual(yaml);
+  });
+
+  it('sorts runtime and agent maps in the deterministic renderer', (): void => {
+    const roster = parseRosterV2(
+      validRoster
+        .replace(
+          'runtimes:\n  pi:\n    reset_command: /new',
+          'runtimes:\n  pi:\n    reset_command: /new\n  codex:\n    reset_command: /clear',
+        )
+        .replace(
+          'agents:\n  - name: coder0',
+          'agents:\n  - name: reviewer\n    alias: Reviewer\n    class: review\n    runtime: pi\n    provider: openai\n    model: gpt-5.6-sol\n    reasoning: medium\n    tool_policy: review\n    working_directory: ~/src\n    persistent_persona: false\n    reset_between_tasks: true\n    lifecycle:\n      enabled: true\n      desired_state: stopped\n    launch:\n      yolo: true\n  - name: coder0',
+        ),
+      'yaml',
+    );
+
+    const rendered = renderRosterV2Yaml(roster);
+    expect(rendered.indexOf('  codex:')).toBeLessThan(rendered.indexOf('  pi:'));
+    expect(rendered.indexOf('  - name: coder0')).toBeLessThan(
+      rendered.indexOf('  - name: reviewer'),
+    );
+  });
+
+  it.each([
+    ['v1 document', validRoster.replace('version: 2', 'version: 1'), /v1.*existing v1 path/i],
+    [
+      'unknown connector',
+      `${validRoster}\nconnector:\n  kind: matrix\n`,
+      /unsupported field.*connector/i,
+    ],
+    [
+      'remote host',
+      validRoster.replace(
+        'runtime: pi\n    provider',
+        'runtime: pi\n    host: remote\n    provider',
+      ),
+      /unsupported field.*host/i,
+    ],
+    [
+      'secret reference',
+      validRoster.replace('model: gpt-5.6-sol', 'model: gpt-5.6-sol\n    secret_ref: vault://x'),
+      /unsupported field.*secret_ref/i,
+    ],
+    [
+      'channel override',
+      validRoster.replace('model: gpt-5.6-sol', 'model: gpt-5.6-sol\n    channels: discord'),
+      /unsupported field.*channels/i,
+    ],
+    [
+      'arbitrary command',
+      validRoster.replace('model: gpt-5.6-sol', 'model: gpt-5.6-sol\n    command: whoami'),
+      /unsupported field.*command/i,
+    ],
+    [
+      'gateway field',
+      `${validRoster}\ngateway:\n  url: https://gateway.example\n`,
+      /unsupported field.*gateway/i,
+    ],
+    [
+      'missing required field',
+      validRoster.replace('    model: gpt-5.6-sol\n', ''),
+      /model.*required/i,
+    ],
+    [
+      'invalid type',
+      validRoster.replace('generation: 7', 'generation: seven'),
+      /generation.*integer/i,
+    ],
+    [
+      'unsafe generation',
+      validRoster.replace('generation: 7', 'generation: 9007199254740992'),
+      /generation.*integer/i,
+    ],
+    [
+      'duplicate names',
+      validRoster.replace(
+        '  - name: coder0',
+        '  - name: coder0\n    alias: Duplicate\n    class: code\n    runtime: pi\n    provider: openai\n    model: gpt-5.6-sol\n    reasoning: high\n    tool_policy: code\n    working_directory: ~/src\n    persistent_persona: false\n    reset_between_tasks: true\n    lifecycle:\n      enabled: true\n      desired_state: stopped\n    launch:\n      yolo: true\n  - name: coder0',
+      ),
+      /duplicate agent name/i,
+    ],
+    ['invalid name', validRoster.replace('name: coder0', 'name: ../coder0'), /invalid agent name/i],
+    [
+      'invalid transport',
+      validRoster.replace('transport: tmux', 'transport: matrix'),
+      /transport.*tmux/i,
+    ],
+    [
+      'invalid runtime',
+      validRoster.replace('runtime: pi', 'runtime: matrix'),
+      /runtime.*supported/i,
+    ],
+    [
+      'invalid reasoning',
+      validRoster.replace('reasoning: high', 'reasoning: extreme'),
+      /reasoning.*low.*medium.*high/i,
+    ],
+    [
+      'ambiguous socket',
+      validRoster.replace('socket_name: mosaic-fleet', 'socket_name: default/socket'),
+      /socket_name/i,
+    ],
+    [
+      'agent socket override',
+      validRoster.replace(
+        'runtime: pi\n    provider',
+        'runtime: pi\n    socket: another\n    provider',
+      ),
+      /unsupported field.*socket/i,
+    ],
+  ])('rejects %s', (_name: string, source: string, expected: RegExp): void => {
+    expect((): void => {
+      parseRosterV2(source, 'yaml');
+    }).toThrow(expected);
+  });
+
+  it('rejects malformed JSON as a validation error', (): void => {
+    expect((): void => {
+      parseRosterV2('{', 'json');
+    }).toThrow(RosterV2ValidationError);
+  });
+
+  it('declares supported runtime map keys in the executable schema', (): void => {
+    expect(ROSTER_V2_JSON_SCHEMA).toMatchObject({
+      properties: {
+        runtimes: { propertyNames: { enum: ['claude', 'codex', 'opencode', 'pi'] } },
+      },
+    });
+  });
+
+  it('keeps the checked-in documentation schema structurally identical to the executable schema', async (): Promise<void> => {
+    const schemaPath = fileURLToPath(
+      new URL('../../../../docs/fleet/reference/roster-v2.schema.json', import.meta.url),
+    );
+    const documented = await readFile(schemaPath, 'utf8');
+
+    expect(JSON.parse(documented) as unknown).toEqual(ROSTER_V2_JSON_SCHEMA);
+  });
+});

packages/mosaic/src/fleet/roster-v2.ts

@@ -0,0 +1,473 @@
+import YAML from 'yaml';
+
+export const ROSTER_V2_SUPPORTED_RUNTIMES = ['claude', 'codex', 'opencode', 'pi'] as const;
+export const ROSTER_V2_REASONING_LEVELS = ['low', 'medium', 'high'] as const;
+export const ROSTER_V2_DESIRED_STATES = ['running', 'stopped'] as const;
+
+export type RosterV2RuntimeName = (typeof ROSTER_V2_SUPPORTED_RUNTIMES)[number];
+export type RosterV2ReasoningLevel = (typeof ROSTER_V2_REASONING_LEVELS)[number];
+export type RosterV2DesiredState = (typeof ROSTER_V2_DESIRED_STATES)[number];
+export type RosterV2InputFormat = 'json' | 'yaml';
+
+export interface FleetRosterV2Tmux {
+  readonly socketName: string;
+  readonly holderSession: string;
+}
+
+export interface FleetRosterV2Defaults {
+  readonly workingDirectory: string;
+  readonly runtime: RosterV2RuntimeName;
+}
+
+export interface FleetRosterV2Runtime {
+  readonly resetCommand: string;
+}
+
+export interface FleetRosterV2Lifecycle {
+  readonly enabled: boolean;
+  readonly desiredState: RosterV2DesiredState;
+}
+
+export interface FleetRosterV2Launch {
+  readonly yolo: boolean;
+}
+
+export interface FleetRosterV2Agent {
+  readonly name: string;
+  readonly alias: string;
+  readonly className: string;
+  readonly runtime: RosterV2RuntimeName;
+  readonly provider: string;
+  readonly model: string;
+  readonly reasoning: RosterV2ReasoningLevel;
+  readonly toolPolicy: string;
+  readonly workingDirectory: string;
+  readonly persistentPersona: boolean;
+  readonly resetBetweenTasks: boolean;
+  readonly lifecycle: FleetRosterV2Lifecycle;
+  readonly launch: FleetRosterV2Launch;
+}
+
+export interface FleetRosterV2 {
+  readonly version: 2;
+  readonly generation: number;
+  readonly transport: 'tmux';
+  readonly tmux: FleetRosterV2Tmux;
+  readonly defaults: FleetRosterV2Defaults;
+  readonly runtimes: Readonly<Record<string, FleetRosterV2Runtime>>;
+  readonly agents: readonly FleetRosterV2Agent[];
+}
+
+export class RosterV2ValidationError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = 'RosterV2ValidationError';
+  }
+}
+
+type JsonSchema = string | number | boolean | null | JsonSchema[] | { [key: string]: JsonSchema };
+
+/**
+ * Executable v2 structural contract. The checked-in documentation schema is
+ * structurally compared to this value in roster-v2.spec.ts.
+ */
+export const ROSTER_V2_JSON_SCHEMA: JsonSchema = {
+  $schema: 'https://json-schema.org/draft/2020-12/schema',
+  $id: 'https://mosaicstack.dev/schemas/fleet/roster-v2.schema.json',
+  title: 'Mosaic local tmux fleet roster v2',
+  type: 'object',
+  additionalProperties: false,
+  required: ['version', 'generation', 'transport', 'tmux', 'defaults', 'runtimes', 'agents'],
+  properties: {
+    version: { const: 2 },
+    generation: { type: 'integer', minimum: 1, maximum: Number.MAX_SAFE_INTEGER },
+    transport: { const: 'tmux' },
+    tmux: {
+      type: 'object',
+      additionalProperties: false,
+      required: ['socket_name', 'holder_session'],
+      properties: {
+        socket_name: { type: 'string', pattern: '^[A-Za-z0-9_.-]+$' },
+        holder_session: { type: 'string', pattern: '^[A-Za-z0-9_.-]+$' },
+      },
+    },
+    defaults: {
+      type: 'object',
+      additionalProperties: false,
+      required: ['working_directory', 'runtime'],
+      properties: {
+        working_directory: { type: 'string', minLength: 1 },
+        runtime: { enum: [...ROSTER_V2_SUPPORTED_RUNTIMES] },
+      },
+    },
+    runtimes: {
+      type: 'object',
+      minProperties: 1,
+      propertyNames: { enum: [...ROSTER_V2_SUPPORTED_RUNTIMES] },
+      additionalProperties: {
+        type: 'object',
+        additionalProperties: false,
+        required: ['reset_command'],
+        properties: { reset_command: { type: 'string', minLength: 1 } },
+      },
+    },
+    agents: {
+      type: 'array',
+      minItems: 1,
+      items: {
+        type: 'object',
+        additionalProperties: false,
+        required: [
+          'name',
+          'alias',
+          'class',
+          'runtime',
+          'provider',
+          'model',
+          'reasoning',
+          'tool_policy',
+          'working_directory',
+          'persistent_persona',
+          'reset_between_tasks',
+          'lifecycle',
+          'launch',
+        ],
+        properties: {
+          name: { type: 'string', pattern: '^[A-Za-z0-9][A-Za-z0-9_.-]*$' },
+          alias: { type: 'string', minLength: 1 },
+          class: { type: 'string', pattern: '^[a-z][a-z0-9-]*$' },
+          runtime: { enum: [...ROSTER_V2_SUPPORTED_RUNTIMES] },
+          provider: { type: 'string', minLength: 1 },
+          model: { type: 'string', minLength: 1 },
+          reasoning: { enum: [...ROSTER_V2_REASONING_LEVELS] },
+          tool_policy: { type: 'string', pattern: '^[a-z][a-z0-9-]*$' },
+          working_directory: { type: 'string', minLength: 1 },
+          persistent_persona: { type: 'boolean' },
+          reset_between_tasks: { type: 'boolean' },
+          lifecycle: {
+            type: 'object',
+            additionalProperties: false,
+            required: ['enabled', 'desired_state'],
+            properties: {
+              enabled: { type: 'boolean' },
+              desired_state: { enum: [...ROSTER_V2_DESIRED_STATES] },
+            },
+          },
+          launch: {
+            type: 'object',
+            additionalProperties: false,
+            required: ['yolo'],
+            properties: { yolo: { type: 'boolean' } },
+          },
+        },
+      },
+    },
+  },
+};
+
+const ROOT_KEYS = ['version', 'generation', 'transport', 'tmux', 'defaults', 'runtimes', 'agents'];
+const TMUX_KEYS = ['socket_name', 'holder_session'];
+const DEFAULT_KEYS = ['working_directory', 'runtime'];
+const RUNTIME_KEYS = ['reset_command'];
+const AGENT_KEYS = [
+  'name',
+  'alias',
+  'class',
+  'runtime',
+  'provider',
+  'model',
+  'reasoning',
+  'tool_policy',
+  'working_directory',
+  'persistent_persona',
+  'reset_between_tasks',
+  'lifecycle',
+  'launch',
+];
+const LIFECYCLE_KEYS = ['enabled', 'desired_state'];
+const LAUNCH_KEYS = ['yolo'];
+const IDENTIFIER = /^[A-Za-z0-9][A-Za-z0-9_.-]*$/;
+const TMUX_IDENTIFIER = /^[A-Za-z0-9_.-]+$/;
+const POLICY_IDENTIFIER = /^[a-z][a-z0-9-]*$/;
+
+/** Parses YAML or JSON and compiles only the local-tmux roster v2 contract. */
+export function parseRosterV2(source: string, format?: RosterV2InputFormat): FleetRosterV2 {
+  const parsed = parseSource(source, format);
+  return normalizeRosterV2(parsed);
+}
+
+/** Renders canonical snake_case YAML with sorted runtime and agent entries. */
+export function renderRosterV2Yaml(roster: FleetRosterV2): string {
+  const normalized = normalizeRosterV2(toSourceShape(roster));
+  return YAML.stringify(toSourceShape(normalized));
+}
+
+function parseSource(source: string, format?: RosterV2InputFormat): unknown {
+  const resolvedFormat = format ?? (source.trimStart().startsWith('{') ? 'json' : 'yaml');
+  try {
+    if (resolvedFormat === 'json') return JSON.parse(source) as unknown;
+    return YAML.parse(source) as unknown;
+  } catch (error: unknown) {
+    const detail = error instanceof Error ? error.message : String(error);
+    throw new RosterV2ValidationError(`Roster v2 ${resolvedFormat} parse failed: ${detail}`);
+  }
+}
+
+export function normalizeRosterV2(raw: unknown): FleetRosterV2 {
+  const root = requiredObject(raw, 'Roster v2');
+  assertKnownKeys(root, 'Roster v2', ROOT_KEYS);
+  if (root.version === 1) {
+    throw new RosterV2ValidationError(
+      'Roster v2 compiler rejects v1 input; use the existing v1 path until migration.',
+    );
+  }
+  if (root.version !== 2) throw new RosterV2ValidationError('Roster v2 version must be 2.');
+
+  const generation = requiredPositiveInteger(root.generation, 'Roster v2 generation');
+  const transport = requiredEnum(root.transport, 'Roster v2 transport', ['tmux'] as const);
+  const tmux = normalizeTmux(root.tmux);
+  const defaults = normalizeDefaults(root.defaults);
+  const runtimes = normalizeRuntimes(root.runtimes);
+  const agents = normalizeAgents(root.agents, runtimes);
+
+  if (!runtimes[defaults.runtime]) {
+    throw new RosterV2ValidationError(
+      `Roster v2 defaults runtime "${defaults.runtime}" must be declared in runtimes.`,
+    );
+  }
+  return { version: 2, generation, transport, tmux, defaults, runtimes, agents };
+}
+
+function normalizeTmux(value: unknown): FleetRosterV2Tmux {
+  const raw = requiredObject(value, 'Roster v2 tmux');
+  assertKnownKeys(raw, 'Roster v2 tmux', TMUX_KEYS);
+  return {
+    socketName: requiredTmuxIdentifier(raw.socket_name, 'Roster v2 tmux socket_name'),
+    holderSession: requiredTmuxIdentifier(raw.holder_session, 'Roster v2 tmux holder_session'),
+  };
+}
+
+function normalizeDefaults(value: unknown): FleetRosterV2Defaults {
+  const raw = requiredObject(value, 'Roster v2 defaults');
+  assertKnownKeys(raw, 'Roster v2 defaults', DEFAULT_KEYS);
+  return {
+    workingDirectory: requiredString(raw.working_directory, 'Roster v2 defaults working_directory'),
+    runtime: requiredRuntime(raw.runtime, 'Roster v2 defaults runtime'),
+  };
+}
+
+function normalizeRuntimes(value: unknown): Readonly<Record<string, FleetRosterV2Runtime>> {
+  const raw = requiredObject(value, 'Roster v2 runtimes');
+  const names = Object.keys(raw);
+  if (names.length === 0)
+    throw new RosterV2ValidationError('Roster v2 runtimes must not be empty.');
+
+  const result: Record<string, FleetRosterV2Runtime> = {};
+  for (const name of names.sort()) {
+    const runtime = requiredRuntime(name, 'Roster v2 runtime name');
+    const config = requiredObject(raw[name], `Roster v2 runtime "${runtime}"`);
+    assertKnownKeys(config, `Roster v2 runtime "${runtime}"`, RUNTIME_KEYS);
+    result[runtime] = {
+      resetCommand: requiredString(
+        config.reset_command,
+        `Roster v2 runtime "${runtime}" reset_command`,
+      ),
+    };
+  }
+  return result;
+}
+
+function normalizeAgents(
+  value: unknown,
+  runtimes: Readonly<Record<string, FleetRosterV2Runtime>>,
+): readonly FleetRosterV2Agent[] {
+  if (!Array.isArray(value) || value.length === 0) {
+    throw new RosterV2ValidationError('Roster v2 agents must be a non-empty array.');
+  }
+  const seen = new Set<string>();
+  const agents = value.map((candidate: unknown, index: number): FleetRosterV2Agent => {
+    const raw = requiredObject(candidate, `Roster v2 agents[${index}]`);
+    assertKnownKeys(raw, `Roster v2 agents[${index}]`, AGENT_KEYS);
+    const name = requiredIdentifier(raw.name, `Roster v2 agents[${index}] name`);
+    if (seen.has(name))
+      throw new RosterV2ValidationError(`Roster v2 has duplicate agent name: ${name}.`);
+    seen.add(name);
+    const runtime = requiredRuntime(raw.runtime, `Roster v2 agent "${name}" runtime`);
+    if (!runtimes[runtime]) {
+      throw new RosterV2ValidationError(
+        `Roster v2 agent "${name}" runtime "${runtime}" must be declared in runtimes.`,
+      );
+    }
+    return {
+      name,
+      alias: requiredString(raw.alias, `Roster v2 agent "${name}" alias`),
+      className: requiredPolicyIdentifier(raw.class, `Roster v2 agent "${name}" class`),
+      runtime,
+      provider: requiredString(raw.provider, `Roster v2 agent "${name}" provider`),
+      model: requiredString(raw.model, `Roster v2 agent "${name}" model`),
+      reasoning: requiredEnum(
+        raw.reasoning,
+        `Roster v2 agent "${name}" reasoning`,
+        ROSTER_V2_REASONING_LEVELS,
+      ),
+      toolPolicy: requiredPolicyIdentifier(
+        raw.tool_policy,
+        `Roster v2 agent "${name}" tool_policy`,
+      ),
+      workingDirectory: requiredString(
+        raw.working_directory,
+        `Roster v2 agent "${name}" working_directory`,
+      ),
+      persistentPersona: requiredBoolean(
+        raw.persistent_persona,
+        `Roster v2 agent "${name}" persistent_persona`,
+      ),
+      resetBetweenTasks: requiredBoolean(
+        raw.reset_between_tasks,
+        `Roster v2 agent "${name}" reset_between_tasks`,
+      ),
+      lifecycle: normalizeLifecycle(raw.lifecycle, name),
+      launch: normalizeLaunch(raw.launch, name),
+    };
+  });
+  return agents.sort((left: FleetRosterV2Agent, right: FleetRosterV2Agent): number =>
+    left.name.localeCompare(right.name),
+  );
+}
+
+function normalizeLifecycle(value: unknown, agentName: string): FleetRosterV2Lifecycle {
+  const raw = requiredObject(value, `Roster v2 agent "${agentName}" lifecycle`);
+  assertKnownKeys(raw, `Roster v2 agent "${agentName}" lifecycle`, LIFECYCLE_KEYS);
+  return {
+    enabled: requiredBoolean(raw.enabled, `Roster v2 agent "${agentName}" lifecycle enabled`),
+    desiredState: requiredEnum(
+      raw.desired_state,
+      `Roster v2 agent "${agentName}" lifecycle desired_state`,
+      ROSTER_V2_DESIRED_STATES,
+    ),
+  };
+}
+
+function normalizeLaunch(value: unknown, agentName: string): FleetRosterV2Launch {
+  const raw = requiredObject(value, `Roster v2 agent "${agentName}" launch`);
+  assertKnownKeys(raw, `Roster v2 agent "${agentName}" launch`, LAUNCH_KEYS);
+  return { yolo: requiredBoolean(raw.yolo, `Roster v2 agent "${agentName}" launch yolo`) };
+}
+
+function requiredObject(value: unknown, label: string): Record<string, unknown> {
+  if (typeof value !== 'object' || value === null || Array.isArray(value)) {
+    throw new RosterV2ValidationError(`${label} must be an object.`);
+  }
+  return value as Record<string, unknown>;
+}
+
+function assertKnownKeys(
+  value: Record<string, unknown>,
+  label: string,
+  allowedKeys: readonly string[],
+): void {
+  const allowed = new Set(allowedKeys);
+  const unknown = Object.keys(value).filter((key: string): boolean => !allowed.has(key));
+  if (unknown.length > 0) {
+    throw new RosterV2ValidationError(`${label} has unsupported field(s): ${unknown.join(', ')}.`);
+  }
+}
+
+function requiredString(value: unknown, label: string): string {
+  if (typeof value !== 'string' || value.trim() === '') {
+    throw new RosterV2ValidationError(`${label} is required and must be a non-empty string.`);
+  }
+  return value.trim();
+}
+
+function requiredIdentifier(value: unknown, label: string): string {
+  const result = requiredString(value, label);
+  if (!IDENTIFIER.test(result)) {
+    throw new RosterV2ValidationError(`Invalid agent name (${label}): ${result}.`);
+  }
+  return result;
+}
+
+function requiredTmuxIdentifier(value: unknown, label: string): string {
+  const result = requiredString(value, label);
+  if (!TMUX_IDENTIFIER.test(result))
+    throw new RosterV2ValidationError(`Invalid ${label}: ${result}.`);
+  return result;
+}
+
+function requiredPolicyIdentifier(value: unknown, label: string): string {
+  const result = requiredString(value, label);
+  if (!POLICY_IDENTIFIER.test(result))
+    throw new RosterV2ValidationError(`Invalid ${label}: ${result}.`);
+  return result;
+}
+
+function requiredPositiveInteger(value: unknown, label: string): number {
+  if (typeof value !== 'number' || !Number.isSafeInteger(value) || value < 1) {
+    throw new RosterV2ValidationError(`${label} must be a positive integer.`);
+  }
+  return value;
+}
+
+function requiredBoolean(value: unknown, label: string): boolean {
+  if (typeof value !== 'boolean') throw new RosterV2ValidationError(`${label} must be a boolean.`);
+  return value;
+}
+
+function requiredRuntime(value: unknown, label: string): RosterV2RuntimeName {
+  return requiredEnum(value, label, ROSTER_V2_SUPPORTED_RUNTIMES);
+}
+
+function requiredEnum<T extends string>(value: unknown, label: string, allowed: readonly T[]): T {
+  if (typeof value !== 'string' || !allowed.includes(value as T)) {
+    throw new RosterV2ValidationError(
+      `${label} must be one of the supported values: ${allowed.join(', ')}.`,
+    );
+  }
+  return value as T;
+}
+
+function toSourceShape(roster: FleetRosterV2): Record<string, unknown> {
+  return {
+    version: roster.version,
+    generation: roster.generation,
+    transport: roster.transport,
+    tmux: { socket_name: roster.tmux.socketName, holder_session: roster.tmux.holderSession },
+    defaults: {
+      working_directory: roster.defaults.workingDirectory,
+      runtime: roster.defaults.runtime,
+    },
+    runtimes: Object.fromEntries(
+      Object.entries(roster.runtimes)
+        .sort(([left], [right]): number => left.localeCompare(right))
+        .map(([name, runtime]): [string, unknown] => [
+          name,
+          { reset_command: runtime.resetCommand },
+        ]),
+    ),
+    agents: [...roster.agents]
+      .sort((left: FleetRosterV2Agent, right: FleetRosterV2Agent): number =>
+        left.name.localeCompare(right.name),
+      )
+      .map(
+        (agent: FleetRosterV2Agent): Record<string, unknown> => ({
+          name: agent.name,
+          alias: agent.alias,
+          class: agent.className,
+          runtime: agent.runtime,
+          provider: agent.provider,
+          model: agent.model,
+          reasoning: agent.reasoning,
+          tool_policy: agent.toolPolicy,
+          working_directory: agent.workingDirectory,
+          persistent_persona: agent.persistentPersona,
+          reset_between_tasks: agent.resetBetweenTasks,
+          lifecycle: {
+            enabled: agent.lifecycle.enabled,
+            desired_state: agent.lifecycle.desiredState,
+          },
+          launch: { yolo: agent.launch.yolo },
+        }),
+      ),
+  };
+}