fix(fleet): harden managed launch composition

AMD1213-C: repair stale array consumer, fail closed on foreign link provenance, validate manifests before mutation, and exercise the fleet MCP preflight call path.

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

@@ -20,6 +20,7 @@ import {
   piForceSkillNames,
   registerRuntimeLaunchers,
   checkSequentialThinking,
+  launchFleetRuntimeForTest,
   type RuntimeLaunchHandler,
   type ClaudexLaunchHandler,
 } from './launch.js';
@@ -99,6 +100,95 @@ describe('registerRuntimeLaunchers — non-yolo subcommands', () => {
 });
 
 describe('checkSequentialThinking', () => {
+  it('runs the real fleet launch preflight against the injected seat, not HOME', () => {
+    const home = mkdtempSync(join(tmpdir(), 'mosaic-seq-home-'));
+    const agentDir = mkdtempSync(join(tmpdir(), 'mosaic-seq-seat-'));
+    const installed = mkdtempSync(join(tmpdir(), 'mosaic-seq-installed-'));
+    const checker = join(installed, 'tools', '_scripts', 'mosaic-ensure-sequential-thinking');
+    try {
+      expect(
+        JSON.parse(
+          readFileSync(
+            join(process.cwd(), 'framework', 'runtime', 'claude', 'settings.json'),
+            'utf8',
+          ),
+        ).mcpServers['sequential-thinking'],
+      ).toEqual({
+        command: 'npx',
+        args: ['-y', '@modelcontextprotocol/server-sequential-thinking'],
+      });
+      mkdirSync(join(installed, 'tools', '_scripts'), { recursive: true });
+      copyFileSync(
+        join(process.cwd(), 'framework', 'tools', '_scripts', 'mosaic-ensure-sequential-thinking'),
+        checker,
+      );
+      mkdirSync(join(agentDir, '.claude'), { recursive: true });
+      writeFileSync(
+        join(agentDir, '.claude', '.claude.json'),
+        JSON.stringify({
+          mcpServers: {
+            'sequential-thinking': {
+              command: 'npx',
+              args: ['-y', '@modelcontextprotocol/server-sequential-thinking'],
+            },
+          },
+        }),
+        { mode: 0o600 },
+      );
+      vi.stubEnv('HOME', home);
+      const final = vi.fn((): never => {
+        throw new Error('final runtime boundary');
+      });
+      expect(() =>
+        launchFleetRuntimeForTest('claude', [], {}, { agentDir, mosaicHome: installed }, final),
+      ).toThrow('final runtime boundary');
+      expect(final).toHaveBeenCalledOnce();
+    } finally {
+      vi.unstubAllEnvs();
+      rmSync(home, { recursive: true, force: true });
+      rmSync(agentDir, { recursive: true, force: true });
+      rmSync(installed, { recursive: true, force: true });
+    }
+  });
+
+  it('fails the real fleet launch preflight when only operator HOME is seeded', () => {
+    const home = mkdtempSync(join(tmpdir(), 'mosaic-seq-home-'));
+    const agentDir = mkdtempSync(join(tmpdir(), 'mosaic-seq-seat-'));
+    const installed = mkdtempSync(join(tmpdir(), 'mosaic-seq-installed-'));
+    const checker = join(installed, 'tools', '_scripts', 'mosaic-ensure-sequential-thinking');
+    const exit = vi.spyOn(process, 'exit').mockImplementation(exitThrows);
+    try {
+      mkdirSync(join(installed, 'tools', '_scripts'), { recursive: true });
+      copyFileSync(
+        join(process.cwd(), 'framework', 'tools', '_scripts', 'mosaic-ensure-sequential-thinking'),
+        checker,
+      );
+      writeFileSync(
+        join(home, '.claude.json'),
+        JSON.stringify({
+          mcpServers: {
+            'sequential-thinking': {
+              command: 'npx',
+              args: ['-y', '@modelcontextprotocol/server-sequential-thinking'],
+            },
+          },
+        }),
+      );
+      vi.stubEnv('HOME', home);
+      expect(() =>
+        launchFleetRuntimeForTest('claude', [], {}, { agentDir, mosaicHome: installed }, () => {
+          throw new Error('must not execute');
+        }),
+      ).toThrow('process.exit called');
+    } finally {
+      exit.mockRestore();
+      vi.unstubAllEnvs();
+      rmSync(home, { recursive: true, force: true });
+      rmSync(agentDir, { recursive: true, force: true });
+      rmSync(installed, { recursive: true, force: true });
+    }
+  });
+
   it('passes with a seeded seat even when operator HOME has no MCP configuration', () => {
     const home = mkdtempSync(join(tmpdir(), 'mosaic-seq-home-'));
     const agentDir = mkdtempSync(join(tmpdir(), 'mosaic-seq-seat-'));
@@ -121,6 +211,7 @@ describe('checkSequentialThinking', () => {
             },
           },
         }),
+        { mode: 0o600 },
       );
       vi.stubEnv('MOSAIC_HOME', installed);
       vi.stubEnv('HOME', home);
@@ -156,6 +247,7 @@ describe('checkSequentialThinking', () => {
       writeFileSync(
         join(agentDir, '.claude', '.claude.json'),
         JSON.stringify({ hasCompletedOnboarding: true, theme: 'dark' }),
+        { mode: 0o600 },
       );
       const env = { ...process.env, HOME: home, PATH: `${bin}:${process.env.PATH}` };
       expect(