refactor: centralize task runtime contracts (#199)

runners/shared/test/task-runtime.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  DEFAULT_SCHEDULE_TASK_CONTEXT_MODE,
+  DEFAULT_TASK_CONTEXT_MODE,
+  DEFAULT_WATCH_CI_CONTEXT_MODE,
+  TASK_CONTEXT_MODES,
+  WATCH_CI_PROMPT_PREFIX,
+  isTaskContextMode,
+  normalizeTaskContextMode,
+} from '../src/task-runtime.js';
+
+describe('task runtime constants', () => {
+  it('defines the task context modes and default', () => {
+    expect(TASK_CONTEXT_MODES).toEqual(['group', 'isolated']);
+    expect(DEFAULT_TASK_CONTEXT_MODE).toBe('isolated');
+    expect(DEFAULT_SCHEDULE_TASK_CONTEXT_MODE).toBe('group');
+    expect(DEFAULT_WATCH_CI_CONTEXT_MODE).toBe('isolated');
+  });
+
+  it('normalizes task context modes consistently', () => {
+    expect(isTaskContextMode('group')).toBe(true);
+    expect(isTaskContextMode('isolated')).toBe(true);
+    expect(isTaskContextMode('invalid')).toBe(false);
+    expect(normalizeTaskContextMode('group')).toBe('group');
+    expect(normalizeTaskContextMode('invalid')).toBe('isolated');
+  });
+
+  it('defines the watch CI prompt sentinel', () => {
+    expect(WATCH_CI_PROMPT_PREFIX).toBe('[BACKGROUND CI WATCH]');
+  });
+});