test: V1 gate coverage — writing-style resolver + config + jargon + migration + dormancy

Six new gate-tier test files:

- test/writing-style-resolver.test.ts — asserts Writing Style section
  is injected into tier-≥2 preamble, all 6 rules present, jargon list
  inlined, terse-mode gate condition present, Codex output uses
  \$GSTACK_BIN (not ~/.claude/), tier-1 does NOT get the section,
  migration-prompt block present.

- test/explain-level-config.test.ts — gstack-config set/get round-trip
  for default + terse, unknown-value warns + defaults to default,
  header documents the key, round-trip across set→set→get.

- test/jargon-list.test.ts — shape + ~50 terms + no duplicates
  (case-insensitive) + includes canonical high-signal terms.

- test/v0-dormancy.test.ts — 5D dimension names + archetype names
  forbidden in default-mode tier-≥2 SKILL.md output, except for
  plan-tune and office-hours where they're load-bearing.

- test/readme-throughput.test.ts — script replaces anchor with number
  on happy path, writes PENDING marker when JSON missing, CI gate
  asserts committed README contains no PENDING string.

- test/upgrade-migration-v1.test.ts — fresh run writes pending flag,
  idempotent after user-answered, pre-existing explain_level counts
  as answered.

All 95 V1 test-expect() calls pass. Full suite: 0 failures.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/explain-level-config.test.ts

@@ -0,0 +1,83 @@
+/**
+ * gstack-config explain_level round-trip + validation tests.
+ *
+ * Coverage:
+ * - `set explain_level default` persists, `get` returns "default"
+ * - `set explain_level terse` persists, `get` returns "terse"
+ * - `set explain_level garbage` warns + writes "default"
+ * - `get explain_level` with unset key returns empty (preamble bash defaults)
+ * - Annotated config header documents explain_level
+ */
+import { describe, test, expect, beforeEach, afterEach } from 'bun:test';
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+import { spawnSync } from 'child_process';
+
+const ROOT = path.resolve(import.meta.dir, '..');
+const BIN_CONFIG = path.join(ROOT, 'bin', 'gstack-config');
+
+let tmpHome: string;
+
+beforeEach(() => {
+  tmpHome = fs.mkdtempSync(path.join(os.tmpdir(), 'gstack-cfg-test-'));
+});
+
+afterEach(() => {
+  fs.rmSync(tmpHome, { recursive: true, force: true });
+});
+
+function run(...args: string[]): { stdout: string; stderr: string; status: number } {
+  const res = spawnSync(BIN_CONFIG, args, {
+    env: { ...process.env, GSTACK_STATE_DIR: tmpHome },
+    encoding: 'utf-8',
+    cwd: ROOT,
+  });
+  return {
+    stdout: (res.stdout ?? '').trim(),
+    stderr: (res.stderr ?? '').trim(),
+    status: res.status ?? -1,
+  };
+}
+
+describe('gstack-config explain_level', () => {
+  test('set + get default round-trip', () => {
+    expect(run('set', 'explain_level', 'default').status).toBe(0);
+    expect(run('get', 'explain_level').stdout).toBe('default');
+  });
+
+  test('set + get terse round-trip', () => {
+    expect(run('set', 'explain_level', 'terse').status).toBe(0);
+    expect(run('get', 'explain_level').stdout).toBe('terse');
+  });
+
+  test('unknown value warns and defaults to default', () => {
+    const result = run('set', 'explain_level', 'garbage');
+    expect(result.status).toBe(0);
+    expect(result.stderr).toContain('not recognized');
+    expect(result.stderr).toContain('default, terse');
+    expect(run('get', 'explain_level').stdout).toBe('default');
+  });
+
+  test('get with unset explain_level returns empty (preamble default takes over)', () => {
+    // No prior set → no config file → empty output
+    expect(run('get', 'explain_level').stdout).toBe('');
+  });
+
+  test('config header documents explain_level', () => {
+    // Trigger file creation with any set
+    run('set', 'explain_level', 'default');
+    const cfg = fs.readFileSync(path.join(tmpHome, 'config.yaml'), 'utf-8');
+    expect(cfg).toContain('explain_level');
+    expect(cfg).toContain('default');
+    expect(cfg).toContain('terse');
+  });
+
+  test('set terse, then set garbage restores default', () => {
+    run('set', 'explain_level', 'terse');
+    expect(run('get', 'explain_level').stdout).toBe('terse');
+    const garbage = run('set', 'explain_level', 'nonsense');
+    expect(garbage.stderr).toContain('not recognized');
+    expect(run('get', 'explain_level').stdout).toBe('default');
+  });
+});