Add /compact skill for manual context compaction (#817)

* feat: add /compact skill for manual context compaction

added /compact session command to fight context rot in long-running sessions. Uses Claude Agent SDK's built-in /compact command with auth gating (main-group or is_from_me only).

* simplify: remove group-queue modification, streamline denied path confirmed against fresh-clone merge.

* refactor: extract handleSessionCommand from index.ts into session-commands.ts

Verified: 345/345 tests pass on fresh-clone merge.

.claude/skills/add-compact/tests/add-compact.test.ts

@@ -0,0 +1,188 @@
+import { describe, it, expect, beforeAll } from 'vitest';
+import fs from 'fs';
+import path from 'path';
+
+const SKILL_DIR = path.resolve(__dirname, '..');
+
+describe('add-compact skill package', () => {
+  describe('manifest', () => {
+    let content: string;
+
+    beforeAll(() => {
+      content = fs.readFileSync(path.join(SKILL_DIR, 'manifest.yaml'), 'utf-8');
+    });
+
+    it('has a valid manifest.yaml', () => {
+      expect(fs.existsSync(path.join(SKILL_DIR, 'manifest.yaml'))).toBe(true);
+      expect(content).toContain('skill: add-compact');
+      expect(content).toContain('version: 1.0.0');
+    });
+
+    it('has no npm dependencies', () => {
+      expect(content).toContain('npm_dependencies: {}');
+    });
+
+    it('has no env_additions', () => {
+      expect(content).toContain('env_additions: []');
+    });
+
+    it('lists all add files', () => {
+      expect(content).toContain('src/session-commands.ts');
+      expect(content).toContain('src/session-commands.test.ts');
+    });
+
+    it('lists all modify files', () => {
+      expect(content).toContain('src/index.ts');
+      expect(content).toContain('container/agent-runner/src/index.ts');
+    });
+
+    it('has no dependencies', () => {
+      expect(content).toContain('depends: []');
+    });
+  });
+
+  describe('add/ files', () => {
+    it('includes src/session-commands.ts with required exports', () => {
+      const filePath = path.join(SKILL_DIR, 'add', 'src', 'session-commands.ts');
+      expect(fs.existsSync(filePath)).toBe(true);
+
+      const content = fs.readFileSync(filePath, 'utf-8');
+      expect(content).toContain('export function extractSessionCommand');
+      expect(content).toContain('export function isSessionCommandAllowed');
+      expect(content).toContain('export async function handleSessionCommand');
+      expect(content).toContain("'/compact'");
+    });
+
+    it('includes src/session-commands.test.ts with test cases', () => {
+      const filePath = path.join(SKILL_DIR, 'add', 'src', 'session-commands.test.ts');
+      expect(fs.existsSync(filePath)).toBe(true);
+
+      const content = fs.readFileSync(filePath, 'utf-8');
+      expect(content).toContain('extractSessionCommand');
+      expect(content).toContain('isSessionCommandAllowed');
+      expect(content).toContain('detects bare /compact');
+      expect(content).toContain('denies untrusted sender');
+    });
+  });
+
+  describe('modify/ files exist', () => {
+    const modifyFiles = [
+      'src/index.ts',
+      'container/agent-runner/src/index.ts',
+    ];
+
+    for (const file of modifyFiles) {
+      it(`includes modify/${file}`, () => {
+        const filePath = path.join(SKILL_DIR, 'modify', file);
+        expect(fs.existsSync(filePath)).toBe(true);
+      });
+    }
+  });
+
+  describe('intent files exist', () => {
+    const intentFiles = [
+      'src/index.ts.intent.md',
+      'container/agent-runner/src/index.ts.intent.md',
+    ];
+
+    for (const file of intentFiles) {
+      it(`includes modify/${file}`, () => {
+        const filePath = path.join(SKILL_DIR, 'modify', file);
+        expect(fs.existsSync(filePath)).toBe(true);
+      });
+    }
+  });
+
+  describe('modify/src/index.ts', () => {
+    let content: string;
+
+    beforeAll(() => {
+      content = fs.readFileSync(
+        path.join(SKILL_DIR, 'modify', 'src', 'index.ts'),
+        'utf-8',
+      );
+    });
+
+    it('imports session command helpers', () => {
+      expect(content).toContain("import { extractSessionCommand, handleSessionCommand, isSessionCommandAllowed } from './session-commands.js'");
+    });
+
+    it('uses const for missedMessages', () => {
+      expect(content).toMatch(/const missedMessages = getMessagesSince/);
+    });
+
+    it('delegates to handleSessionCommand in processGroupMessages', () => {
+      expect(content).toContain('Session command interception (before trigger check)');
+      expect(content).toContain('handleSessionCommand(');
+      expect(content).toContain('cmdResult.handled');
+      expect(content).toContain('cmdResult.success');
+    });
+
+    it('passes deps to handleSessionCommand', () => {
+      expect(content).toContain('sendMessage:');
+      expect(content).toContain('setTyping:');
+      expect(content).toContain('runAgent:');
+      expect(content).toContain('closeStdin:');
+      expect(content).toContain('advanceCursor:');
+      expect(content).toContain('formatMessages');
+      expect(content).toContain('canSenderInteract:');
+    });
+
+    it('has session command interception in startMessageLoop', () => {
+      expect(content).toContain('Session command interception (message loop)');
+      expect(content).toContain('queue.enqueueMessageCheck(chatJid)');
+    });
+
+    it('preserves core index.ts structure', () => {
+      expect(content).toContain('processGroupMessages');
+      expect(content).toContain('startMessageLoop');
+      expect(content).toContain('async function main()');
+      expect(content).toContain('recoverPendingMessages');
+      expect(content).toContain('ensureContainerSystemRunning');
+    });
+  });
+
+  describe('modify/container/agent-runner/src/index.ts', () => {
+    let content: string;
+
+    beforeAll(() => {
+      content = fs.readFileSync(
+        path.join(SKILL_DIR, 'modify', 'container', 'agent-runner', 'src', 'index.ts'),
+        'utf-8',
+      );
+    });
+
+    it('defines KNOWN_SESSION_COMMANDS whitelist', () => {
+      expect(content).toContain("KNOWN_SESSION_COMMANDS");
+      expect(content).toContain("'/compact'");
+    });
+
+    it('uses query() with string prompt for slash commands', () => {
+      expect(content).toContain('prompt: trimmedPrompt');
+      expect(content).toContain('allowedTools: []');
+    });
+
+    it('observes compact_boundary system event', () => {
+      expect(content).toContain('compactBoundarySeen');
+      expect(content).toContain("'compact_boundary'");
+      expect(content).toContain('Compact boundary observed');
+    });
+
+    it('handles error subtypes', () => {
+      expect(content).toContain("resultSubtype?.startsWith('error')");
+    });
+
+    it('registers PreCompact hook for slash commands', () => {
+      expect(content).toContain('createPreCompactHook(containerInput.assistantName)');
+    });
+
+    it('preserves core agent-runner structure', () => {
+      expect(content).toContain('async function runQuery');
+      expect(content).toContain('class MessageStream');
+      expect(content).toContain('function writeOutput');
+      expect(content).toContain('function createPreCompactHook');
+      expect(content).toContain('function createSanitizeBashHook');
+      expect(content).toContain('async function main');
+    });
+  });
+});