test: deepen fixture module v2 for reliability (#329)

* test: deepen fixture seam for init/state/workstream suites

* test: deepen fixture module v2 with declarative builders

tests/fixture-builder.test.cjs

@@ -0,0 +1,86 @@
+const { test, describe, afterEach } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('fs');
+const path = require('path');
+const { execSync } = require('child_process');
+
+const { createFixture, seedPhase, seedWorkstream, writeState } = require('./fixtures/index.cjs');
+const { cleanup } = require('./helpers.cjs');
+
+const created = [];
+afterEach(() => {
+  while (created.length > 0) cleanup(created.pop());
+});
+
+describe('fixture builder module', () => {
+  test('creates canonical planning layout by default', () => {
+    const dir = createFixture();
+    created.push(dir);
+
+    assert.ok(fs.existsSync(path.join(dir, '.planning')), 'creates .planning directory');
+    assert.ok(fs.existsSync(path.join(dir, '.planning', 'phases')), 'creates .planning/phases directory');
+  });
+
+  test('seeds phase files declaratively', () => {
+    const dir = createFixture();
+    created.push(dir);
+
+    const phaseDir = seedPhase(dir, '03-api', {
+      '03-01-PLAN.md': '# Plan',
+      '03-CONTEXT.md': '# Context',
+    });
+
+    assert.ok(fs.existsSync(path.join(phaseDir, '03-01-PLAN.md')));
+    assert.ok(fs.existsSync(path.join(phaseDir, '03-CONTEXT.md')));
+  });
+
+  test('seeds workstream and active pointer declaratively', () => {
+    const dir = createFixture();
+    created.push(dir);
+
+    const wsDir = seedWorkstream(dir, {
+      name: 'alpha',
+      state: '# State\n',
+      roadmap: '# Roadmap\n',
+      active: true,
+    });
+
+    assert.ok(fs.existsSync(path.join(wsDir, 'STATE.md')));
+    assert.ok(fs.existsSync(path.join(wsDir, 'ROADMAP.md')));
+    assert.strictEqual(
+      fs.readFileSync(path.join(dir, '.planning', 'active-workstream'), 'utf8').trim(),
+      'alpha'
+    );
+  });
+
+  test('rejects invalid workstream names', () => {
+    const dir = createFixture();
+    created.push(dir);
+    assert.throws(() => seedWorkstream(dir, { name: '../escape' }), /invalid name/);
+  });
+
+  test('writes STATE.md in canonical location', () => {
+    const dir = createFixture();
+    created.push(dir);
+
+    const p = writeState(dir, '# Project State\n');
+    assert.ok(fs.existsSync(p));
+    assert.strictEqual(path.basename(p), 'STATE.md');
+  });
+
+  test('initializes git fixture with initial commit', () => {
+    const dir = createFixture({ git: true });
+    created.push(dir);
+
+    const isWorkTree = execSync('git rev-parse --is-inside-work-tree', { cwd: dir, encoding: 'utf8' }).trim();
+    assert.strictEqual(isWorkTree, 'true', 'fixture should be a git worktree');
+
+    const head = execSync('git rev-parse HEAD', { cwd: dir, encoding: 'utf8' }).trim();
+    assert.ok(head.length > 0, 'fixture should include initial commit');
+
+    assert.ok(
+      fs.existsSync(path.join(dir, '.planning', 'PROJECT.md')),
+      'git fixture writes canonical PROJECT.md'
+    );
+  });
+});