merge: absorb main into next — 23-commit divergence (08-05..13 base=main window)

17 content commits + 3 merge bubbles were genuinely missing from next (~8,000 lines:
goal controller #1152, framework enforcement #1174/#1195, pr-edit wrapper #1173/#1200,
pipefail series #1100/#1105/#1106/#1107, git-tools fixes #1073/#1085/#1086/#1089,
#991, #1007, enrollment tolerance #1094). 3 commits were already in next by content
(#1060 identical, #1066/#1062 evolved twins — conflicts resolved to next's side).

Per-commit classification and evidence: mosaic-brain fleet/lanes/stack-remediation/main-next-divergence.md.
Conflict resolutions (6 files) itemized in the PR body.

packages/mosaic/src/commands/fleet-regen-command.spec.ts

@@ -131,13 +131,14 @@ async function exists(path: string): Promise<boolean> {
 }
 
 describe('projectRosterV2AgentGeneratedEnv', (): void => {
-  it('maps a roster-v2 agent to exactly the eight generated projection keys', (): void => {
+  it('maps a roster-v2 agent to exactly the nine generated projection keys', (): void => {
     const roster = parseRosterV2(rosterYaml, 'yaml');
     const agent = roster.agents.find((candidate) => candidate.name === 'coder0');
     expect(agent).toBeDefined();
     const values = projectRosterV2AgentGeneratedEnv(roster, agent!);
     expect(values).toEqual({
       MOSAIC_AGENT_NAME: 'coder0',
+      MOSAIC_GIT_IDENTITY: 'coder0',
       MOSAIC_AGENT_CLASS: 'code',
       MOSAIC_AGENT_RUNTIME: 'pi',
       MOSAIC_AGENT_MODEL: 'gpt-5.6-sol',

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

@@ -422,6 +422,7 @@ describe('fleet roster parsing', () => {
     expect(generateAgentEnv(roster, getRosterAgent(roster, 'coder0'))).toBe(
       [
         'MOSAIC_AGENT_NAME=coder0',
+        'MOSAIC_GIT_IDENTITY=coder0',
         // Reflects the roster's canonicalized compatibility class (A3a).
         'MOSAIC_AGENT_CLASS=code',
         'MOSAIC_AGENT_RUNTIME=codex',
@@ -3799,6 +3800,7 @@ describe('fleet add command', () => {
       'utf8',
     );
     expect(envContent).toContain('MOSAIC_AGENT_NAME=coder0');
+    expect(envContent).toContain('MOSAIC_GIT_IDENTITY=coder0');
     expect(envContent).toContain('MOSAIC_AGENT_RUNTIME=codex');
   });
 

packages/mosaic/src/commands/fleet.ts

@@ -486,6 +486,7 @@ function generateAgentEnvValues(
   const workingDirectory = agent.workingDirectory ?? roster.defaults.workingDirectory;
   return {
     MOSAIC_AGENT_NAME: agent.name,
+    MOSAIC_GIT_IDENTITY: agent.name,
     MOSAIC_AGENT_CLASS: agent.className,
     MOSAIC_AGENT_RUNTIME: agent.runtime,
     MOSAIC_AGENT_MODEL: agent.modelHint ?? '',

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

@@ -5,6 +5,7 @@ import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import {
   buildPiSkillArgs,
+  discoverPiExtensionArgs,
   enumerateSkillDirs,
   piForceSkillNames,
   registerRuntimeLaunchers,
@@ -178,6 +179,52 @@ describe('buildPiSkillArgs', () => {
   });
 });
 
+describe('discoverPiExtensionArgs', () => {
+  it('loads the core and goal extensions in deterministic order from Mosaic home', () => {
+    const root = mkdtempSync(join(tmpdir(), 'mosaic-pi-extensions-'));
+    const runtimeDir = join(root, 'runtime', 'pi');
+    mkdirSync(runtimeDir, { recursive: true });
+    writeFileSync(join(runtimeDir, 'goal-extension.ts'), '// goal\n');
+    writeFileSync(join(runtimeDir, 'mosaic-extension.ts'), '// core\n');
+
+    try {
+      expect(discoverPiExtensionArgs(root)).toEqual([
+        '--extension',
+        join(runtimeDir, 'mosaic-extension.ts'),
+        '--extension',
+        join(runtimeDir, 'goal-extension.ts'),
+      ]);
+    } finally {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+
+  it('remains backward-compatible when the optional goal extension is absent', () => {
+    const root = mkdtempSync(join(tmpdir(), 'mosaic-pi-extensions-'));
+    const runtimeDir = join(root, 'runtime', 'pi');
+    mkdirSync(runtimeDir, { recursive: true });
+    writeFileSync(join(runtimeDir, 'mosaic-extension.ts'), '// core\n');
+
+    try {
+      expect(discoverPiExtensionArgs(root)).toEqual([
+        '--extension',
+        join(runtimeDir, 'mosaic-extension.ts'),
+      ]);
+    } finally {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+
+  it('emits no extension arguments when Mosaic runtime assets are absent', () => {
+    const root = mkdtempSync(join(tmpdir(), 'mosaic-pi-extensions-'));
+    try {
+      expect(discoverPiExtensionArgs(root)).toEqual([]);
+    } finally {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+});
+
 describe('enumerateSkillDirs (real FS)', () => {
   let root: string;
 

packages/mosaic/src/commands/launch.ts

@@ -921,9 +921,15 @@ export function buildPiSkillArgs(
   return ['--no-skills', ...forcedSkillArgs];
 }
 
-function discoverPiExtension(): string[] {
-  const ext = join(MOSAIC_HOME, 'runtime', 'pi', 'mosaic-extension.ts');
-  return existsSync(ext) ? ['--extension', ext] : [];
+const PI_EXTENSION_FILES = ['mosaic-extension.ts', 'goal-extension.ts'] as const;
+
+export function discoverPiExtensionArgs(mosaicHome: string = MOSAIC_HOME): string[] {
+  const args: string[] = [];
+  for (const fileName of PI_EXTENSION_FILES) {
+    const extensionPath = join(mosaicHome, 'runtime', 'pi', fileName);
+    if (existsSync(extensionPath)) args.push('--extension', extensionPath);
+  }
+  return args;
 }
 
 // ─── Launch functions ────────────────────────────────────────────────────────
@@ -1002,7 +1008,7 @@ function launchRuntime(runtime: RuntimeName, args: string[], yolo: boolean): nev
       const prompt = buildRuntimePrompt('pi');
       const cliArgs = ['--append-system-prompt', prompt];
       cliArgs.push(...buildPiSkillArgs(args));
-      cliArgs.push(...discoverPiExtension());
+      cliArgs.push(...discoverPiExtensionArgs());
       if (hasMissionNoArgs) {
         cliArgs.push(missionPrompt);
       } else {