test(fleet): raise provision spec timeout for I/O-bound CI runs (#665)

Fix #665 test timeout.

packages/mosaic/src/commands/compose-contract.spec.ts

@@ -164,4 +164,89 @@ describe('composeContract — overlay composer', () => {
     expect(composeContract('pi', fixture.home)).toContain('# pi runtime contract');
     expect(composeContract('codex', fixture.home)).not.toContain('# pi runtime contract');
   });
+
+  // ── Persona contract injection (A3b) ──────────────────────────────────────
+  // composeContract reads MOSAIC_AGENT_CLASS and injects the resolved persona
+  // (override-aware). Save/restore the env so these tests don't leak state.
+  describe('persona contract (A3b)', () => {
+    let prevClass: string | undefined;
+
+    beforeEach(() => {
+      prevClass = process.env['MOSAIC_AGENT_CLASS'];
+    });
+
+    afterEach(() => {
+      if (prevClass === undefined) delete process.env['MOSAIC_AGENT_CLASS'];
+      else process.env['MOSAIC_AGENT_CLASS'] = prevClass;
+    });
+
+    const seedBaseline = (klass: string, body: string): void => {
+      mkdirSync(join(fixture.home, 'fleet', 'roles'), { recursive: true });
+      writeFileSync(join(fixture.home, 'fleet', 'roles', `${klass}.md`), body);
+    };
+    const seedOverride = (klass: string, body: string): void => {
+      mkdirSync(join(fixture.home, 'fleet', 'roles.local'), { recursive: true });
+      writeFileSync(join(fixture.home, 'fleet', 'roles.local', `${klass}.md`), body);
+    };
+
+    it('injects the baseline persona when MOSAIC_AGENT_CLASS is set and a role file exists', () => {
+      seedBaseline('coder', '# Coder\n\n(`class: coder`)\n\nBASELINE-MANDATE: ship the lane.\n');
+      process.env['MOSAIC_AGENT_CLASS'] = 'coder';
+      const out = composeContract('claude', fixture.home);
+      expect(out).toContain('# Persona Contract (coder)');
+      expect(out).toContain('BASELINE-MANDATE');
+    });
+
+    it('OVERRIDE WINS at launch: roles.local persona is injected over baseline (AC-NS-7)', () => {
+      seedBaseline('coder', '# Coder\n\n(`class: coder`)\n\nBASELINE-MANDATE.\n');
+      seedOverride('coder', '# Coder (override)\n\n(`class: coder`)\n\nOVERRIDE-MANDATE.\n');
+      process.env['MOSAIC_AGENT_CLASS'] = 'coder';
+      const out = composeContract('claude', fixture.home);
+      expect(out).toContain('# Persona Contract (coder)');
+      expect(out).toContain('OVERRIDE-MANDATE');
+      expect(out).not.toContain('BASELINE-MANDATE');
+    });
+
+    it('does NOT inject a persona when MOSAIC_AGENT_CLASS is unset', () => {
+      seedBaseline('coder', '# Coder\n\n(`class: coder`)\n\nBASELINE-MANDATE.\n');
+      delete process.env['MOSAIC_AGENT_CLASS'];
+      const out = composeContract('claude', fixture.home);
+      expect(out).not.toContain('# Persona Contract');
+    });
+
+    it('does NOT inject (no throw) when MOSAIC_AGENT_CLASS names an unknown class', () => {
+      seedBaseline('coder', '# Coder\n\n(`class: coder`)\n\nBASELINE-MANDATE.\n');
+      process.env['MOSAIC_AGENT_CLASS'] = 'nonexistent';
+      expect(() => composeContract('claude', fixture.home)).not.toThrow();
+      expect(composeContract('claude', fixture.home)).not.toContain('# Persona Contract');
+    });
+
+    it('places the persona contract BEFORE the fleet comms block (identity, then peers)', () => {
+      seedBaseline('enhancer', '# Enhancer\n\n(`class: enhancer`)\n\nIMPROVE.\n');
+      mkdirSync(join(fixture.home, 'fleet'), { recursive: true });
+      writeFileSync(
+        join(fixture.home, 'fleet', 'roster.yaml'),
+        [
+          'agents:',
+          '  - name: orchestrator',
+          '    class: orchestrator',
+          '  - name: enhancer',
+          '    class: enhancer',
+          '',
+        ].join('\n'),
+      );
+      const prevName = process.env['MOSAIC_AGENT_NAME'];
+      try {
+        process.env['MOSAIC_AGENT_CLASS'] = 'enhancer';
+        process.env['MOSAIC_AGENT_NAME'] = 'enhancer';
+        const out = composeContract('claude', fixture.home);
+        expect(out).toContain('# Persona Contract (enhancer)');
+        expect(out).toContain('# Fleet Comms');
+        expect(out.indexOf('# Persona Contract')).toBeLessThan(out.indexOf('# Fleet Comms'));
+      } finally {
+        if (prevName === undefined) delete process.env['MOSAIC_AGENT_NAME'];
+        else process.env['MOSAIC_AGENT_NAME'] = prevName;
+      }
+    });
+  });
 });

packages/mosaic/src/commands/fleet-personas.ts

@@ -25,6 +25,7 @@
  * can reference a customized or user-added persona.
  */
 
+import { readFileSync, readdirSync } from 'node:fs';
 import { readFile, readdir } from 'node:fs/promises';
 import { homedir } from 'node:os';
 import { basename, join } from 'node:path';
@@ -88,13 +89,12 @@ export interface DirClasses {
  * classes still appear in `classes` for membership checks.
  */
 export async function extractClassesFromDir(dir: string): Promise<DirClasses> {
-  const classes = new Set<string>();
+  const acc: DirClasses = { classes: new Set<string>(), byClass: new Map<string, PersonaFile>() };
-  const byClass = new Map<string, PersonaFile>();
   let entries: string[];
   try {
     entries = await readdir(dir);
   } catch {
-    return { classes, byClass };
+    return acc;
   }
 
   for (const entry of entries) {
@@ -105,36 +105,75 @@ export async function extractClassesFromDir(dir: string): Promise<DirClasses> {
     } catch {
       continue;
     }
-    if (entry === 'LIBRARY.md') {
+    accumulateEntry(acc, dir, entry, text);
-      for (const m of text.matchAll(LIBRARY_ROW)) {
+  }
-        const name = m[1];
+  return acc;
-        if (name && name !== 'persona') classes.add(name);
+}
-      }
+
+/**
+ * Synchronous twin of {@link extractClassesFromDir}. Identical extraction
+ * semantics (same markers, same union of marker/filename/LIBRARY sources) on
+ * sync fs, for the synchronous launch-time prompt path (composeContract) which
+ * cannot await. Missing dir / unreadable files degrade gracefully.
+ */
+export function extractClassesFromDirSync(dir: string): DirClasses {
+  const acc: DirClasses = { classes: new Set<string>(), byClass: new Map<string, PersonaFile>() };
+  let entries: string[];
+  try {
+    entries = readdirSync(dir);
+  } catch {
+    return acc;
+  }
+
+  for (const entry of entries) {
+    if (!entry.endsWith('.md')) continue;
+    let text: string;
+    try {
+      text = readFileSync(join(dir, entry), 'utf8');
+    } catch {
       continue;
     }
-    // The filename stem is itself a valid class (covers marker-less alias docs).
+    accumulateEntry(acc, dir, entry, text);
-    const stem = basename(entry, '.md');
+  }
-    classes.add(stem);
+  return acc;
-    const domainMatch = DOMAIN_MARKER.exec(text);
+}
-    const domain = domainMatch?.[1];
+
-    let markedClassForFile: string | undefined;
+/**
-    for (const m of text.matchAll(CLASS_MARKER)) {
+ * Apply the class-extraction rules for ONE role file's text into `acc`. Pure
-      const klass = m[1];
+ * over already-read content, so the async and sync directory scanners share a
-      if (!klass) continue;
+ * single definition of "what classes a file contributes" (DRY — no semantic
-      classes.add(klass);
+ * drift between the launch-time and command-time paths).
-      // Record the FIRST marker as the file's defining class (the prose names
+ */
-      // the persona's own class up top; later mentions reference siblings).
+function accumulateEntry(acc: DirClasses, dir: string, entry: string, text: string): void {
-      if (!markedClassForFile) {
+  const { classes, byClass } = acc;
-        markedClassForFile = klass;
+  if (entry === 'LIBRARY.md') {
-        byClass.set(klass, { klass, file: join(dir, entry), ...(domain ? { domain } : {}) });
+    for (const m of text.matchAll(LIBRARY_ROW)) {
-      }
+      const name = m[1];
+      if (name && name !== 'persona') classes.add(name);
     }
-    // A marker-less file still maps its stem to itself (no domain known).
+    return;
-    if (!markedClassForFile && !byClass.has(stem)) {
+  }
-      byClass.set(stem, { klass: stem, file: join(dir, entry) });
+  // The filename stem is itself a valid class (covers marker-less alias docs).
+  const stem = basename(entry, '.md');
+  classes.add(stem);
+  const domainMatch = DOMAIN_MARKER.exec(text);
+  const domain = domainMatch?.[1];
+  let markedClassForFile: string | undefined;
+  for (const m of text.matchAll(CLASS_MARKER)) {
+    const klass = m[1];
+    if (!klass) continue;
+    classes.add(klass);
+    // Record the FIRST marker as the file's defining class (the prose names
+    // the persona's own class up top; later mentions reference siblings).
+    if (!markedClassForFile) {
+      markedClassForFile = klass;
+      byClass.set(klass, { klass, file: join(dir, entry), ...(domain ? { domain } : {}) });
     }
   }
-  return { classes, byClass };
+  // A marker-less file still maps its stem to itself (no domain known).
+  if (!markedClassForFile && !byClass.has(stem)) {
+    byClass.set(stem, { klass: stem, file: join(dir, entry) });
+  }
 }
 
 export interface PersonaDirs {
@@ -195,6 +234,21 @@ export async function resolvePersona(
     extractClassesFromDir(rolesDir),
     extractClassesFromDir(overrideDir),
   ]);
+  return resolvePersonaFrom(klass, { rolesDir, overrideDir, base, over });
+}
+
+/**
+ * Resolve a single class against ALREADY-EXTRACTED layer maps. Callers that
+ * resolve many classes against the same two directories (e.g. provisioning a
+ * full roster) should {@link extractClassesFromDir} each dir ONCE and reuse the
+ * result here, rather than paying a full directory re-scan per class. Precedence
+ * is identical to {@link resolvePersona}: override layer wins, then baseline.
+ */
+export async function resolvePersonaFrom(
+  klass: string,
+  layers: { rolesDir: string; overrideDir: string; base: DirClasses; over: DirClasses },
+): Promise<PersonaResolution | null> {
+  const { rolesDir, overrideDir, base, over } = layers;
 
   const fromLayer = async (
     dir: string,
@@ -229,6 +283,51 @@ export async function resolvePersona(
   );
 }
 
+/**
+ * Synchronous twin of {@link resolvePersona} — same override-wins precedence
+ * (roles.local/ beats roles/, by marker first then filename stem), returning
+ * null if neither layer defines the class. Exists for the synchronous launch
+ * prompt path (composeContract → readPersonaContractBlock) which cannot await.
+ * Keeping it here, beside the async resolver, keeps the resolution semantics in
+ * one module so the launch-time and command-time resolutions never diverge.
+ */
+export function resolvePersonaSync(
+  klass: string,
+  opts: PersonaDirs = {},
+): PersonaResolution | null {
+  const { rolesDir, overrideDir } = resolveDirs(opts);
+  const base = extractClassesFromDirSync(rolesDir);
+  const over = extractClassesFromDirSync(overrideDir);
+
+  const fromLayer = (
+    dir: string,
+    extracted: DirClasses,
+    layer: PersonaLayer,
+  ): PersonaResolution | null => {
+    // Prefer the marker-defined file; fall back to the filename stem.
+    const pf = extracted.byClass.get(klass);
+    if (!pf) {
+      if (!extracted.classes.has(klass)) return null;
+      const byName = join(dir, `${klass}.md`);
+      try {
+        const content = readFileSync(byName, 'utf8');
+        const dm = DOMAIN_MARKER.exec(content);
+        return { klass, layer, file: byName, content, ...(dm?.[1] ? { domain: dm[1] } : {}) };
+      } catch {
+        return null;
+      }
+    }
+    try {
+      const content = readFileSync(pf.file, 'utf8');
+      return { klass, layer, file: pf.file, content, ...(pf.domain ? { domain: pf.domain } : {}) };
+    } catch {
+      return null;
+    }
+  };
+
+  return fromLayer(overrideDir, over, 'override') ?? fromLayer(rolesDir, base, 'baseline');
+}
+
 export interface PersonaStatusEntry {
   klass: string;
   status: PersonaStatus;

packages/mosaic/src/commands/fleet-provision.spec.ts

@@ -0,0 +1,270 @@
+import { access, mkdir, mkdtemp, rm, writeFile } from 'node:fs/promises';
+import { constants } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { dirname, join, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { loadFleetRoster } from './fleet.js';
+import { generateRoster, runProvision } from './fleet-provision.js';
+import { loadProfile } from './fleet-profiles.js';
+
+// These are INTEGRATION tests: each exercises real filesystem I/O — scanning the
+// committed framework/fleet persona library, rendering YAML, writing to a temp
+// mosaicHome, and round-tripping through the real roster parser. On a heavily
+// contended CI runner (the whole monorepo's suites run in parallel) that genuine
+// I/O can exceed vitest's 5s default even though it completes in ~400ms locally.
+// Give the legitimately I/O-bound work generous headroom so CI is deterministic.
+vi.setConfig({ testTimeout: 30_000 });
+
+// The real, committed library: packages/mosaic/src/commands -> framework/fleet.
+const frameworkFleet = resolve(
+  dirname(fileURLToPath(import.meta.url)),
+  '..',
+  '..',
+  'framework',
+  'fleet',
+);
+const rolesDir = join(frameworkFleet, 'roles');
+const profilesDir = join(frameworkFleet, 'profiles');
+
+/** A fresh temp mosaicHome whose fleet/ dir is empty (for write-path tests). */
+async function freshMosaicHome(): Promise<string> {
+  const home = await mkdtemp(join(tmpdir(), 'mosaic-provision-'));
+  await mkdir(join(home, 'fleet'), { recursive: true });
+  return home;
+}
+
+async function fileExists(path: string): Promise<boolean> {
+  try {
+    await access(path, constants.F_OK);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+describe('provision software-delivery (floor, default)', () => {
+  it('materializes only the floor seats with correct flags + valid scaffold', async () => {
+    const profile = await loadProfile('software-delivery', { profilesDir, rolesDir });
+    const { seats, yaml } = await generateRoster(profile, { profilesDir, rolesDir });
+
+    // Floor is orchestrator + enhancer.
+    expect(seats.map((s) => s.name).sort()).toEqual(['enhancer', 'orchestrator']);
+    const orch = seats.find((s) => s.name === 'orchestrator');
+    const enh = seats.find((s) => s.name === 'enhancer');
+    // RULE 2: floor + lead get persistent_persona.
+    expect(orch?.persistentPersona).toBe(true);
+    expect(enh?.persistentPersona).toBe(true);
+    // RULE 3: floor/lead do NOT reset between tasks.
+    expect(orch?.resetBetweenTasks).toBeUndefined();
+    expect(enh?.resetBetweenTasks).toBeUndefined();
+    // RULE 4: default runtime claude.
+    expect(orch?.runtime).toBe('claude');
+
+    // Scaffold round-trips through the real parser.
+    expect(yaml).toContain('version: 1');
+    expect(yaml).toContain('transport: tmux');
+    expect(yaml).toContain('socket_name: mosaic-fleet');
+  });
+});
+
+describe('provision --full', () => {
+  it('expands the entire roster, including multiplicity, deterministically', async () => {
+    const profile = await loadProfile('software-delivery', { profilesDir, rolesDir });
+    const { seats } = await generateRoster(profile, { full: true, profilesDir, rolesDir });
+
+    const names = seats.map((s) => s.name);
+    // code multiplicity 2 -> code0/code1 (RULE 1).
+    expect(names).toContain('code0');
+    expect(names).toContain('code1');
+    expect(names).not.toContain('code');
+    // Singleton seats keep the bare class name.
+    expect(names).toContain('planner');
+    expect(names).toContain('merge-gate');
+
+    // Deterministic ordering: profile roster order, multiplicity expanded inline.
+    const codeIdx0 = names.indexOf('code0');
+    expect(names[codeIdx0 + 1]).toBe('code1');
+
+    // RULE 3: a non-floor, non-lead execution seat resets between tasks.
+    const code0 = seats.find((s) => s.name === 'code0');
+    expect(code0?.resetBetweenTasks).toBe(true);
+    expect(code0?.persistentPersona).toBeUndefined();
+
+    // Seat count == sum of multiplicities.
+    const expected = profile.roster.reduce((n, e) => n + e.multiplicity, 0);
+    expect(seats.length).toBe(expected);
+  });
+});
+
+describe('generated roster round-trips through the real parser', () => {
+  it('feeds generated YAML back through loadFleetRoster (key correctness proof)', async () => {
+    const home = await freshMosaicHome();
+    try {
+      const result = await runProvision('software-delivery', {
+        mosaicHome: home,
+        profilesDir,
+        rolesDir,
+        full: true,
+        write: true,
+      });
+      expect(result.wrote).toBe(join(home, 'fleet', 'roster.yaml'));
+
+      const parsed = await loadFleetRoster(result.wrote!);
+      // It parses with no error and carries every seat.
+      const profile = await loadProfile('software-delivery', { profilesDir, rolesDir });
+      const expected = profile.roster.reduce((n, e) => n + e.multiplicity, 0);
+      expect(parsed.agents.length).toBe(expected);
+      // Classes survive the round-trip.
+      expect(parsed.agents.some((a) => a.className === 'orchestrator')).toBe(true);
+      expect(parsed.agents.filter((a) => a.className === 'code').length).toBe(2);
+      // reports_to must NOT have been emitted (parser rejects unknown keys).
+      expect(result.yaml).not.toContain('reports_to');
+    } finally {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+});
+
+describe('override-aware persona validation', () => {
+  let dir: string;
+  beforeEach(async () => {
+    dir = await mkdtemp(join(tmpdir(), 'mosaic-provision-ov-'));
+  });
+  afterEach(async () => {
+    await rm(dir, { recursive: true, force: true });
+  });
+
+  it('resolves a user-added (roles.local-only) persona without a false unresolved error', async () => {
+    const overrideDir = join(dir, 'roles.local');
+    const customProfilesDir = join(dir, 'profiles');
+    await mkdir(overrideDir, { recursive: true });
+    await mkdir(customProfilesDir, { recursive: true });
+    // A brand-new class that exists ONLY in roles.local.
+    await writeFile(
+      join(overrideDir, 'widget-maker.md'),
+      '# widget-maker\n\nThe widget-maker persona (`class: widget-maker`).\n',
+    );
+    await writeFile(
+      join(customProfilesDir, 'custom.yaml'),
+      [
+        'id: custom',
+        'title: Custom',
+        'description: a custom system',
+        'lead: widget-maker',
+        'floor: [widget-maker]',
+        'roster:',
+        '  - class: widget-maker',
+        '',
+      ].join('\n'),
+    );
+
+    const result = await runProvision('custom', {
+      mosaicHome: dir,
+      profilesDir: customProfilesDir,
+      // Point baseline rolesDir at a missing dir so resolution depends on override.
+      rolesDir: join(dir, 'no-baseline'),
+      overrideDir,
+    });
+    expect(result.yaml).toContain('class: widget-maker');
+    // It resolved from the override layer.
+    // (generateRoster records personaLayer; the seat is present.)
+    expect(result.summary).toContain('persona=override');
+  });
+
+  it('FAILS with a clear message when a profile references a bogus class', async () => {
+    const customProfilesDir = join(dir, 'profiles');
+    await mkdir(customProfilesDir, { recursive: true });
+    await writeFile(
+      join(customProfilesDir, 'bogus.yaml'),
+      [
+        'id: bogus',
+        'title: Bogus',
+        'description: bad system',
+        'lead: orchestrator',
+        'floor: [orchestrator]',
+        'roster:',
+        '  - class: orchestrator',
+        '  - class: not-a-real-persona-xyz',
+        '    reports_to: orchestrator',
+        '',
+      ].join('\n'),
+    );
+    await expect(
+      runProvision('bogus', {
+        mosaicHome: dir,
+        profilesDir: customProfilesDir,
+        rolesDir,
+        overrideDir: join(dir, 'roles.local'),
+      }),
+    ).rejects.toThrow(/not-a-real-persona-xyz|not a known persona class/);
+  });
+});
+
+describe('--write protection', () => {
+  it('refuses to clobber an existing roster.yaml without --force', async () => {
+    const home = await freshMosaicHome();
+    try {
+      const rosterPath = join(home, 'fleet', 'roster.yaml');
+      await writeFile(rosterPath, 'version: 1\n# operator customizations\n');
+      await expect(
+        runProvision('software-delivery', { mosaicHome: home, profilesDir, rolesDir, write: true }),
+      ).rejects.toThrow(/Refusing to overwrite/);
+      // The original file is untouched.
+      const { readFile } = await import('node:fs/promises');
+      expect(await readFile(rosterPath, 'utf8')).toContain('operator customizations');
+    } finally {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
+  it('--write --force overwrites an existing roster', async () => {
+    const home = await freshMosaicHome();
+    try {
+      const rosterPath = join(home, 'fleet', 'roster.yaml');
+      await writeFile(rosterPath, 'version: 1\n# old\n');
+      const result = await runProvision('software-delivery', {
+        mosaicHome: home,
+        profilesDir,
+        rolesDir,
+        write: true,
+        force: true,
+      });
+      expect(result.wrote).toBe(rosterPath);
+      const parsed = await loadFleetRoster(rosterPath);
+      expect(parsed.agents.length).toBeGreaterThan(0);
+    } finally {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
+  it('--write to a fresh mosaicHome creates the roster file', async () => {
+    const home = await freshMosaicHome();
+    try {
+      const result = await runProvision('software-delivery', {
+        mosaicHome: home,
+        profilesDir,
+        rolesDir,
+        write: true,
+      });
+      expect(await fileExists(result.wrote!)).toBe(true);
+    } finally {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
+  it('dry run (no --write) writes nothing', async () => {
+    const home = await freshMosaicHome();
+    try {
+      const result = await runProvision('software-delivery', {
+        mosaicHome: home,
+        profilesDir,
+        rolesDir,
+      });
+      expect(result.wrote).toBeUndefined();
+      expect(await fileExists(join(home, 'fleet', 'roster.yaml'))).toBe(false);
+    } finally {
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+});

packages/mosaic/src/commands/fleet-provision.ts

@@ -0,0 +1,406 @@
+/**
+ * `mosaic fleet provision --profile <id>` — turn a declared SYSTEM TYPE (a
+ * profile) into a concrete fleet roster (North Star H3).
+ *
+ * A profile (fleet/profiles/<id>.yaml) is a DECLARATIVE mapping from a system
+ * type to a persona roster + org topology (H2). This command MATERIALIZES that
+ * declaration into the concrete `roster.yaml` shape the live fleet consumes — the
+ * same shape `fleet.ts` parses (version/transport/tmux/defaults/runtimes/agents).
+ *
+ * DRY-RUN-FIRST + REVIEWABLE: with no --write it prints the roster it WOULD
+ * generate plus a topology summary and writes nothing. --write persists it, and
+ * REFUSES to clobber an existing roster.yaml without --force (protects operator
+ * customizations).
+ *
+ * DRY: profile parsing/validation is reused wholesale from fleet-profiles.ts
+ * (loadProfile/validateProfile) and persona resolution from fleet-personas.ts
+ * (resolvePersona, override-aware). This module owns ONLY the profile→roster
+ * generation policy, documented inline below so each default is reviewable.
+ */
+
+import { access, mkdir, writeFile } from 'node:fs/promises';
+import { constants } from 'node:fs';
+import { homedir } from 'node:os';
+import { dirname, join } from 'node:path';
+import type { Command } from 'commander';
+import YAML from 'yaml';
+import {
+  loadProfile,
+  validateProfile,
+  type FleetProfile,
+  type ProfileRosterEntry,
+  defaultProfilesDir,
+  defaultRolesDir,
+  listPersonaClassesWithOverrides,
+} from './fleet-profiles.js';
+import {
+  defaultOverrideDir,
+  extractClassesFromDir,
+  resolvePersonaFrom,
+  type PersonaLayer,
+} from './fleet-personas.js';
+
+function defaultMosaicHome(): string {
+  return process.env['MOSAIC_HOME'] ?? join(homedir(), '.config', 'mosaic');
+}
+
+// ---------------------------------------------------------------------------
+// GENERATION RULES — each default below is intentionally simple and documented
+// so a reviewer can ratify or override the policy. See the PR body for the open
+// runtime-per-class question (RULE 4).
+// ---------------------------------------------------------------------------
+
+/**
+ * RULE 4 — Runtime assignment policy (THE one open design question).
+ *
+ * Default: EVERY seat → `runtime: claude`. Claude runs every persona, so it is
+ * the safe universal default and guarantees a structurally-valid, launchable
+ * roster regardless of how the policy ultimately lands. We deliberately do NOT
+ * hardcode pi / gpt-5.5 per class here. The live roster today runs coders on
+ * pi + openai-codex/gpt-5.5:high — whether provisioning should encode a
+ * class→runtime/model map (and WHERE: the profile schema vs a separate
+ * runtime-policy file) is flagged in the PR body for ratification.
+ *
+ * Centralized so changing the policy is a ONE-edit change. If a future profile
+ * entry (or persona) declares a runtime/model preference, honor it here; until
+ * then everything defaults to claude.
+ */
+export const DEFAULT_RUNTIME = 'claude';
+
+/** Result of applying the runtime policy to one seat. */
+interface RuntimeChoice {
+  runtime: string;
+  modelHint?: string;
+}
+
+/**
+ * The single centralized runtime-policy function. Today it returns the universal
+ * `claude` default for every seat. To encode a class→runtime/model map later,
+ * edit ONLY this function (and/or extend the profile schema and read it here).
+ */
+export function resolveSeatRuntime(
+  _klass: string,
+  _isFloor: boolean,
+  _isLead: boolean,
+): RuntimeChoice {
+  return { runtime: DEFAULT_RUNTIME };
+}
+
+/** One generated seat, fully resolved for emission + topology display. */
+export interface GeneratedSeat {
+  name: string;
+  className: string;
+  runtime: string;
+  modelHint?: string;
+  persistentPersona?: boolean;
+  resetBetweenTasks?: boolean;
+  /** Topology edge from the profile (NOT emitted to roster.yaml — see RULE 6). */
+  reportsTo?: string;
+  /** Which persona layer the class resolved from (baseline/override). */
+  personaLayer: PersonaLayer;
+}
+
+export interface GenerateRosterResult {
+  seats: GeneratedSeat[];
+  /** The roster.yaml text (parser-valid, drop-in). */
+  yaml: string;
+}
+
+export interface ProvisionOptions {
+  /** Materialize the entire profile roster (multiplicity expanded). */
+  full?: boolean;
+  mosaicHome?: string;
+  /** Test overrides — mirror fleet-profiles LoadProfilesOptions. */
+  profilesDir?: string;
+  rolesDir?: string;
+  overrideDir?: string;
+}
+
+function resolveDirs(opts: ProvisionOptions): {
+  mosaicHome: string;
+  profilesDir: string;
+  rolesDir: string;
+  overrideDir: string;
+} {
+  const mosaicHome = opts.mosaicHome ?? defaultMosaicHome();
+  return {
+    mosaicHome,
+    profilesDir: opts.profilesDir ?? defaultProfilesDir(mosaicHome),
+    rolesDir: opts.rolesDir ?? defaultRolesDir(mosaicHome),
+    overrideDir: opts.overrideDir ?? defaultOverrideDir(mosaicHome),
+  };
+}
+
+/**
+ * RULE 1 — Seat naming. multiplicity 1 → name = class (e.g. `planner`).
+ * multiplicity N>1 → `<class>0`,`<class>1`,… (e.g. `code` ×2 → code0/code1).
+ * Names are deterministic, following profile roster order.
+ */
+function seatNames(entry: ProfileRosterEntry): string[] {
+  if (entry.multiplicity <= 1) return [entry.class];
+  return Array.from({ length: entry.multiplicity }, (_, i) => `${entry.class}${i}`);
+}
+
+/**
+ * Generate the concrete seats + roster.yaml for a validated profile.
+ *
+ * Seat selection:
+ *   --full  → the ENTIRE profile roster, multiplicity expanded.
+ *   default → ONLY the `floor` classes (the always-staffed minimum), matching
+ *             the profile note "two-agent floor always staffed; every other seat
+ *             added on demand."
+ *
+ * Per-seat flags:
+ *   RULE 2 persistent_persona: true for floor classes AND the lead; else omitted.
+ *   RULE 3 reset_between_tasks: true for non-floor, non-lead execution seats;
+ *           floor/lead omit it (mirrors today's coders resetting while the
+ *           orchestrator/enhancer do not).
+ *   RULE 4 runtime: via resolveSeatRuntime (defaults claude).
+ *   RULE 6 reports_to: tracked on the seat for the topology summary but NOT
+ *           emitted to roster.yaml — the fleet.ts parser rejects unknown agent
+ *           keys, so writing reports_to would break round-trip. Confirmed against
+ *           normalizeAgent's allow-list in fleet.ts.
+ *
+ * Persona resolution: every emitted class is resolved override-aware via
+ * resolvePersona so we can (a) record the layer for the summary and (b) refuse
+ * to emit a roster that references a nonexistent persona.
+ */
+export async function generateRoster(
+  profile: FleetProfile,
+  opts: ProvisionOptions,
+): Promise<GenerateRosterResult> {
+  const { rolesDir, overrideDir } = resolveDirs(opts);
+  const floor = new Set(profile.floor);
+  const lead = profile.lead;
+
+  const selected: ProfileRosterEntry[] = opts.full
+    ? profile.roster
+    : profile.roster.filter((e) => floor.has(e.class));
+
+  // Scan the persona directories ONCE, then resolve every roster entry against
+  // the in-memory maps. resolvePersona() would otherwise re-scan both dirs per
+  // entry — O(entries × files) redundant reads that push --full provisioning
+  // past the test timeout on slow/contended filesystems.
+  const [base, over] = await Promise.all([
+    extractClassesFromDir(rolesDir),
+    extractClassesFromDir(overrideDir),
+  ]);
+
+  const seats: GeneratedSeat[] = [];
+  for (const entry of selected) {
+    const isFloor = floor.has(entry.class);
+    const isLead = entry.class === lead;
+
+    const resolved = await resolvePersonaFrom(entry.class, { rolesDir, overrideDir, base, over });
+    if (!resolved) {
+      // Defensive: validateProfile already guards this, but a class can resolve
+      // for membership yet have no readable file. Fail loudly rather than emit a
+      // roster pointing at a persona we cannot load.
+      throw new Error(
+        `Cannot provision: roster class "${entry.class}" does not resolve to a readable persona.`,
+      );
+    }
+
+    const runtimeChoice = resolveSeatRuntime(entry.class, isFloor, isLead);
+    for (const name of seatNames(entry)) {
+      const seat: GeneratedSeat = {
+        name,
+        className: entry.class,
+        runtime: runtimeChoice.runtime,
+        personaLayer: resolved.layer,
+      };
+      if (runtimeChoice.modelHint) seat.modelHint = runtimeChoice.modelHint;
+      if (isFloor || isLead) seat.persistentPersona = true;
+      if (!isFloor && !isLead) seat.resetBetweenTasks = true;
+      if (entry.reportsTo) seat.reportsTo = entry.reportsTo;
+      seats.push(seat);
+    }
+  }
+
+  if (seats.length === 0) {
+    throw new Error(
+      `Profile "${profile.id}" produced no seats. ` +
+        (opts.full ? 'Its roster is empty.' : 'No floor seats are defined — try --full.'),
+    );
+  }
+
+  return { seats, yaml: renderRosterYaml(seats) };
+}
+
+/**
+ * RULE 5 — Standard roster scaffolding. We emit the same generic, non-personal
+ * scaffold the committed example presets use (socket_name: mosaic-fleet,
+ * holder_session: _holder, working_directory: ~, claude + pi runtimes) so the
+ * output is a drop-in valid roster. No operator-personal data is copied.
+ *
+ * Built via the `yaml` lib (same serializer the parser uses) so the result
+ * round-trips. reports_to is intentionally NOT included on agents (RULE 6).
+ */
+function renderRosterYaml(seats: GeneratedSeat[]): string {
+  const agents = seats.map((s) => {
+    const a: Record<string, unknown> = {
+      name: s.name,
+      runtime: s.runtime,
+      class: s.className,
+    };
+    if (s.persistentPersona) a['persistent_persona'] = true;
+    if (s.modelHint) a['model_hint'] = s.modelHint;
+    if (s.resetBetweenTasks) a['reset_between_tasks'] = true;
+    return a;
+  });
+
+  const doc = {
+    version: 1,
+    transport: 'tmux',
+    tmux: { socket_name: 'mosaic-fleet', holder_session: '_holder' },
+    defaults: { working_directory: '~' },
+    runtimes: {
+      claude: { reset_command: '/clear' },
+      pi: { reset_command: '/new' },
+    },
+    agents,
+  };
+
+  return YAML.stringify(doc);
+}
+
+// ---------------------------------------------------------------------------
+// Validation — reuse fleet-profiles.validateProfile (override-aware classes) and
+// name any unresolved class clearly. Never generate a roster referencing a
+// nonexistent persona.
+// ---------------------------------------------------------------------------
+
+/**
+ * Validate the profile against the override-aware persona library. Throws with a
+ * clear, class-naming message if any referenced class is unresolved.
+ */
+export async function validateProfileForProvision(
+  profile: FleetProfile,
+  opts: ProvisionOptions,
+): Promise<void> {
+  const { rolesDir, overrideDir } = resolveDirs(opts);
+  const validClasses = await listPersonaClassesWithOverrides(rolesDir, overrideDir);
+  const problems = validateProfile(profile, validClasses);
+  if (problems.length > 0) {
+    throw new Error(
+      `Profile "${profile.id}" is invalid; cannot provision:\n  - ${problems.join('\n  - ')}`,
+    );
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Topology summary (printed in dry-run and after write).
+// ---------------------------------------------------------------------------
+
+function formatTopologySummary(seats: GeneratedSeat[]): string {
+  const lines: string[] = [];
+  lines.push(`Topology (${seats.length} seat(s)):`);
+  for (const s of seats) {
+    const reports = s.reportsTo ? `reports_to=${s.reportsTo}` : 'reports_to=- (lead)';
+    lines.push(
+      `  - ${s.name}\tclass=${s.className}\truntime=${s.runtime}\t${reports}\tpersona=${s.personaLayer}`,
+    );
+  }
+  return lines.join('\n');
+}
+
+// ---------------------------------------------------------------------------
+// CLI wiring — mirror registerFleetProfileCommand / registerFleetPersonaCommand.
+// ---------------------------------------------------------------------------
+
+export interface ProvisionRunResult {
+  yaml: string;
+  summary: string;
+  wrote?: string;
+}
+
+/**
+ * Core provision flow shared by the CLI: load + validate the profile, generate
+ * the roster, optionally write it. Returns the artifacts for printing/testing.
+ */
+export async function runProvision(
+  profileId: string,
+  opts: ProvisionOptions & { write?: boolean; force?: boolean },
+): Promise<ProvisionRunResult> {
+  const dirs = resolveDirs(opts);
+  const profile = await loadProfile(profileId, {
+    mosaicHome: dirs.mosaicHome,
+    profilesDir: dirs.profilesDir,
+    rolesDir: dirs.rolesDir,
+    overrideDir: dirs.overrideDir,
+  });
+  // loadProfile already validates, but re-run with our explicit error wording so
+  // an unresolved class is named clearly even if invoked directly.
+  await validateProfileForProvision(profile, opts);
+
+  const { seats, yaml } = await generateRoster(profile, opts);
+  const summary = formatTopologySummary(seats);
+
+  if (!opts.write) {
+    return { yaml, summary };
+  }
+
+  const rosterPath = join(dirs.mosaicHome, 'fleet', 'roster.yaml');
+  if (!opts.force) {
+    let exists = false;
+    try {
+      await access(rosterPath, constants.F_OK);
+      exists = true;
+    } catch {
+      exists = false;
+    }
+    if (exists) {
+      throw new Error(
+        `Refusing to overwrite existing roster: ${rosterPath}. ` +
+          `Pass --force to overwrite, or edit it by hand.`,
+      );
+    }
+  }
+  await mkdir(dirname(rosterPath), { recursive: true });
+  await writeFile(rosterPath, yaml, 'utf8');
+  return { yaml, summary, wrote: rosterPath };
+}
+
+/**
+ * Register `provision` under an existing `fleet` command. `mosaicHomeFor`
+ * resolves the active --mosaic-home (parent flag) at call time, exactly like the
+ * profile/persona/backlog subcommands.
+ */
+export function registerFleetProvisionCommand(
+  fleetCmd: Command,
+  mosaicHomeFor: () => string,
+): Command {
+  const provisionCmd = fleetCmd
+    .command('provision')
+    .description('Materialize a roster.yaml from a system-type profile (H3). DRY-RUN by default.')
+    .requiredOption('--profile <id>', 'System-type profile id to provision')
+    .option('--full', 'Materialize the entire profile roster (default: floor seats only)')
+    .option('--write', 'Write the generated roster to <mosaicHome>/fleet/roster.yaml')
+    .option('--force', 'Overwrite an existing roster.yaml (requires --write)')
+    .action(async (opts: { profile: string; full?: boolean; write?: boolean; force?: boolean }) => {
+      try {
+        const result = await runProvision(opts.profile, {
+          mosaicHome: mosaicHomeFor(),
+          full: opts.full,
+          write: opts.write,
+          force: opts.force,
+        });
+        if (result.wrote) {
+          console.log(`Wrote roster: ${result.wrote}`);
+          console.log('');
+          console.log(result.summary);
+        } else {
+          // DRY RUN: print the roster it WOULD generate + topology, write nothing.
+          console.log('# DRY RUN — no files written. Re-run with --write to persist.');
+          console.log(result.yaml.trimEnd());
+          console.log('');
+          console.log(result.summary);
+        }
+      } catch (err) {
+        process.stderr.write(`${err instanceof Error ? err.message : String(err)}\n`);
+        process.exitCode = 1;
+      }
+    });
+
+  return provisionCmd;
+}

packages/mosaic/src/commands/fleet.spec.ts

@@ -84,6 +84,7 @@ describe('registerFleetCommand', () => {
       'install-systemd',
       'persona',
       'profile',
+      'provision',
       'ps',
       'remove',
       'restart',
@@ -246,6 +247,8 @@ describe('fleet roster parsing', () => {
     expect(generateAgentEnv(roster, getRosterAgent(roster, 'coder0'))).toBe(
       [
         'MOSAIC_AGENT_NAME=coder0',
+        // Reflects the roster's non-default `class: implementer` (A3a).
+        'MOSAIC_AGENT_CLASS=implementer',
         'MOSAIC_AGENT_RUNTIME=codex',
         'MOSAIC_AGENT_MODEL=',
         'MOSAIC_AGENT_WORKDIR=/srv/mosaic',
@@ -255,6 +258,40 @@ describe('fleet roster parsing', () => {
     );
   });
 
+  it('emits MOSAIC_AGENT_CLASS=worker for an agent that declares no class', async () => {
+    cleanup = await tempDir();
+    const rosterPath = join(cleanup, 'roster.json');
+    await writeFile(
+      rosterPath,
+      JSON.stringify({
+        version: 1,
+        transport: 'tmux',
+        agents: [{ name: 'coder0', runtime: 'codex' }],
+      }),
+    );
+    const roster = await loadFleetRoster(rosterPath);
+    expect(generateAgentEnv(roster, getRosterAgent(roster, 'coder0'))).toContain(
+      'MOSAIC_AGENT_CLASS=worker\n',
+    );
+  });
+
+  it('shell-escapes MOSAIC_AGENT_CLASS so a launcher reads it verbatim', async () => {
+    cleanup = await tempDir();
+    const rosterPath = join(cleanup, 'roster.json');
+    await writeFile(
+      rosterPath,
+      JSON.stringify({
+        version: 1,
+        transport: 'tmux',
+        agents: [{ name: 'coder0', runtime: 'codex', class: 'orchestrator' }],
+      }),
+    );
+    const roster = await loadFleetRoster(rosterPath);
+    expect(generateAgentEnv(roster, getRosterAgent(roster, 'coder0'))).toContain(
+      'MOSAIC_AGENT_CLASS=orchestrator\n',
+    );
+  });
+
   it('preserves site-owned agent EnvironmentFile overrides while refreshing roster keys', () => {
     const generated = [
       'MOSAIC_AGENT_NAME=coder0',
@@ -286,6 +323,28 @@ describe('fleet roster parsing', () => {
     );
   });
 
+  it('updates (does not duplicate) MOSAIC_AGENT_CLASS on re-launch', () => {
+    const generated = [
+      'MOSAIC_AGENT_NAME=coder0',
+      'MOSAIC_AGENT_CLASS=orchestrator',
+      'MOSAIC_AGENT_RUNTIME=codex',
+      '',
+    ].join('\n');
+    const existing = [
+      'MOSAIC_AGENT_NAME=coder0',
+      'MOSAIC_AGENT_CLASS=worker',
+      'MOSAIC_AGENT_RUNTIME=codex',
+      '',
+    ].join('\n');
+
+    const merged = mergeAgentEnv(generated, existing);
+    // mergeAgentEnv keys by VAR name, so the regenerated CLASS wins and there is
+    // exactly one MOSAIC_AGENT_CLASS line (no stale worker value left behind).
+    expect(merged).toContain('MOSAIC_AGENT_CLASS=orchestrator');
+    expect(merged).not.toContain('MOSAIC_AGENT_CLASS=worker');
+    expect(merged.match(/^MOSAIC_AGENT_CLASS=/gm)).toHaveLength(1);
+  });
+
   it('rejects unknown roster fields instead of silently defaulting', async () => {
     cleanup = await tempDir();
     const rosterPath = join(cleanup, 'roster.yaml');

packages/mosaic/src/commands/fleet.ts

@@ -11,6 +11,7 @@ import { resolveCommsBlock } from '../fleet/comms-onboarding.js';
 import { registerFleetBacklogCommand } from './fleet-backlog.js';
 import { registerFleetPersonaCommand } from './fleet-personas.js';
 import { registerFleetProfileCommand } from './fleet-profiles.js';
+import { registerFleetProvisionCommand } from './fleet-provision.js';
 
 /**
  * A function that spawns a command with inherited stdio (TTY passthrough).
@@ -490,6 +491,9 @@ export function generateAgentEnv(roster: FleetRoster, agent: FleetAgent): string
   const workingDirectory = agent.workingDirectory ?? roster.defaults.workingDirectory;
   return [
     `MOSAIC_AGENT_NAME=${shellEnvValue(agent.name)}`,
+    // Per-agent class → start-agent-session.sh / launcher reads this to inject the
+    // matching persona contract for the agent's class (default `worker`).
+    `MOSAIC_AGENT_CLASS=${shellEnvValue(agent.className)}`,
     `MOSAIC_AGENT_RUNTIME=${shellEnvValue(agent.runtime)}`,
     // Per-agent model hint → start-agent-session.sh appends `--model <hint>` to
     // the `mosaic yolo` launch so workers run on the roster's model (e.g. pi on
@@ -1717,6 +1721,10 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
   // --mosaic-home flag.
   registerFleetPersonaCommand(cmd, () => cmd.opts<{ mosaicHome: string }>().mosaicHome);
 
+  // Provisioning (H3): materialize a concrete roster.yaml from a system-type
+  // profile. DRY-RUN by default; --write persists under the same --mosaic-home.
+  registerFleetProvisionCommand(cmd, () => cmd.opts<{ mosaicHome: string }>().mosaicHome);
+
   return cmd;
 }
 

packages/mosaic/src/commands/launch.ts

@@ -20,6 +20,7 @@ import { homedir } from 'node:os';
 import { join, dirname } from 'node:path';
 import type { Command } from 'commander';
 import { readFleetCommsBlock } from '../fleet/comms-onboarding.js';
+import { readPersonaContractBlock } from '../fleet/persona-contract.js';
 
 const MOSAIC_HOME = process.env['MOSAIC_HOME'] ?? join(homedir(), '.config', 'mosaic');
 
@@ -384,6 +385,16 @@ For required push/merge/issue-close/release actions, execute without routine con
   // Runtime-specific contract
   parts.push('\n\n# Runtime-Specific Contract\n\n' + readFileSync(runtimeFile, 'utf-8'));
 
+  // Persona contract (A3b): when this agent was spawned with a class
+  // (MOSAIC_AGENT_CLASS, exported into the pane env by A3a), inject its resolved
+  // role contract so its identity (mandate + boundaries) is resident from the
+  // first turn. Override-aware via the persona resolver: a user-customized
+  // persona in fleet/roles.local/ wins over the baseline (AC-NS-7 launch proof).
+  // Placed BEFORE fleet comms: identity first, then how-to-reach-peers. No-ops
+  // silently when the class is unset/unknown (mirrors the comms block).
+  const persona = readPersonaContractBlock(mosaicHome, process.env['MOSAIC_AGENT_CLASS']);
+  if (persona) parts.push('\n\n' + persona);
+
   // Fleet onboarding: when this is a spawned fleet agent (MOSAIC_AGENT_NAME set
   // and present in the roster), inject a comms cheat-sheet + peer roster so it
   // knows how to reach the orchestrator and its peers from its first turn.

packages/mosaic/src/fleet/persona-contract.spec.ts

@@ -0,0 +1,106 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { mkdtempSync, mkdirSync, writeFileSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { readPersonaContractBlock } from './persona-contract.js';
+
+/**
+ * Persona-contract launch injection (A3b). Asserts the override-aware resolver
+ * is wired so a customized persona in roles.local/ wins at launch (AC-NS-7), and
+ * that any miss (unset/empty/unknown class, missing file) no-ops silently —
+ * never throws — mirroring readFleetCommsBlock's tolerant contract.
+ */
+
+const BASELINE_CODER = `# Coder — fleet role definition
+
+The **coder** persona (\`class: coder\`, \`domain: engineering\`).
+
+## Mandate
+
+BASELINE-MANDATE: implement the assigned lane.
+`;
+
+const OVERRIDE_CODER = `# Coder — fleet role definition (override)
+
+The **coder** persona (\`class: coder\`).
+
+## Mandate
+
+OVERRIDE-MANDATE: implement the assigned lane, the user's way.
+`;
+
+function makeHome(): string {
+  const root = mkdtempSync(join(tmpdir(), 'mosaic-persona-'));
+  return join(root, 'mosaic-home');
+}
+
+function seedBaseline(home: string, klass: string, body: string): void {
+  const dir = join(home, 'fleet', 'roles');
+  mkdirSync(dir, { recursive: true });
+  writeFileSync(join(dir, `${klass}.md`), body);
+}
+
+function seedOverride(home: string, klass: string, body: string): void {
+  const dir = join(home, 'fleet', 'roles.local');
+  mkdirSync(dir, { recursive: true });
+  writeFileSync(join(dir, `${klass}.md`), body);
+}
+
+describe('readPersonaContractBlock — launch-time persona injection (A3b)', () => {
+  let home: string;
+
+  beforeEach(() => {
+    home = makeHome();
+  });
+
+  afterEach(() => {
+    // root is the parent of mosaic-home
+    rmSync(join(home, '..'), { recursive: true, force: true });
+  });
+
+  it('injects the baseline persona when the class has a fleet/roles/<class>.md', () => {
+    seedBaseline(home, 'coder', BASELINE_CODER);
+    const block = readPersonaContractBlock(home, 'coder');
+    expect(block).toContain('# Persona Contract (coder)');
+    expect(block).toContain('BASELINE-MANDATE');
+    expect(block).toContain('baseline `fleet/roles/` layer');
+  });
+
+  it('OVERRIDE WINS: roles.local/<class>.md content is injected over the baseline (AC-NS-7)', () => {
+    seedBaseline(home, 'coder', BASELINE_CODER);
+    seedOverride(home, 'coder', OVERRIDE_CODER);
+    const block = readPersonaContractBlock(home, 'coder');
+    expect(block).toContain('# Persona Contract (coder)');
+    expect(block).toContain('OVERRIDE-MANDATE'); // override body present
+    expect(block).not.toContain('BASELINE-MANDATE'); // baseline NOT used
+    expect(block).toContain('roles.local'); // layer note names the override layer
+  });
+
+  it('injects an override-only (user-added) persona with no baseline at all', () => {
+    seedOverride(home, 'reviewer', '# Reviewer\n\n(`class: reviewer`)\n\nCUSTOM-ROLE.\n');
+    const block = readPersonaContractBlock(home, 'reviewer');
+    expect(block).toContain('# Persona Contract (reviewer)');
+    expect(block).toContain('CUSTOM-ROLE');
+  });
+
+  it('no-ops (empty string) when the class is undefined', () => {
+    seedBaseline(home, 'coder', BASELINE_CODER);
+    expect(readPersonaContractBlock(home, undefined)).toBe('');
+  });
+
+  it('no-ops (empty string) when the class is empty/whitespace', () => {
+    seedBaseline(home, 'coder', BASELINE_CODER);
+    expect(readPersonaContractBlock(home, '')).toBe('');
+    expect(readPersonaContractBlock(home, '   ')).toBe('');
+  });
+
+  it('no-ops (empty string) for an unknown class with no role file', () => {
+    seedBaseline(home, 'coder', BASELINE_CODER);
+    expect(readPersonaContractBlock(home, 'nonexistent')).toBe('');
+  });
+
+  it('no-ops (empty string, no throw) when no roles directories exist at all', () => {
+    expect(() => readPersonaContractBlock(home, 'coder')).not.toThrow();
+    expect(readPersonaContractBlock(home, 'coder')).toBe('');
+  });
+});

packages/mosaic/src/fleet/persona-contract.ts

@@ -0,0 +1,63 @@
+/**
+ * Persona-contract injection at launch (North Star A3b).
+ *
+ * A spawned fleet agent should boot already knowing WHO it is: its class's role
+ * contract (mandate + boundaries). The companion goal A3a exports the agent's
+ * resolved class into the pane env as `MOSAIC_AGENT_CLASS`; here we read that
+ * class at launch (composeContract → system prompt) and inject the resolved
+ * persona contract so the identity is resident from the agent's first turn.
+ *
+ * OVERRIDE-AWARE: resolution goes through fleet-personas' resolver, so a
+ * user-customized persona in the PRESERVE-protected `fleet/roles.local/` layer
+ * WINS over the baseline `fleet/roles/` of the same class. That is the
+ * launch-time proof of AC-NS-7 — a customized persona actually reaches the model
+ * when the agent boots, not just in `mosaic fleet persona show`.
+ *
+ * Tolerant by contract (mirrors readFleetCommsBlock): an empty/missing class, an
+ * unknown class, or a missing role file all yield '' so the launcher no-ops
+ * silently. This MUST never throw during launch.
+ *
+ * Standalone module (no fleet.ts import) to keep launch.ts's prompt path free of
+ * the heavy fleet command module; it depends only on the lightweight persona
+ * resolver.
+ */
+
+import {
+  resolvePersonaSync,
+  defaultRolesDir,
+  defaultOverrideDir,
+} from '../commands/fleet-personas.js';
+
+/**
+ * Resolve `klass`'s persona contract (override-aware) and render it as a
+ * clearly-delimited launch block. Returns '' on any miss (falsy class, unknown
+ * class, missing/unreadable file) so composeContract can push it unconditionally
+ * and have it no-op silently. Never throws.
+ */
+export function readPersonaContractBlock(mosaicHome: string, klass: string | undefined): string {
+  if (!klass || !klass.trim()) return '';
+  let resolved: ReturnType<typeof resolvePersonaSync>;
+  try {
+    resolved = resolvePersonaSync(klass.trim(), {
+      rolesDir: defaultRolesDir(mosaicHome),
+      overrideDir: defaultOverrideDir(mosaicHome),
+    });
+  } catch {
+    // Best-effort onboarding: a resolver hiccup must not abort the launch.
+    return '';
+  }
+  if (!resolved) return '';
+
+  const layerNote =
+    resolved.layer === 'override'
+      ? '_(resolved from the `fleet/roles.local/` override layer — wins over baseline)_'
+      : '_(resolved from the baseline `fleet/roles/` layer)_';
+
+  return `# Persona Contract (${resolved.klass})
+
+${layerNote}
+
+You are operating as the **${resolved.klass}** persona. The role contract below is your identity — its mandate and boundaries govern what you own and what you must not do for this assignment.
+
+${resolved.content.trim()}`;
+}