test: verify human challenge race condition fix ordering (BUG-S2)

waitForHumanResponse synchronously stores pending challenge before
returning, ensuring SSE emit happens after storage. Tests verify
ordering, choice consistency, promise resolution, and cleanup.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/engine/human-responses-ordering.test.ts

@@ -0,0 +1,80 @@
+import { describe, it, expect } from 'vitest'
+import { waitForHumanResponse, getPendingChallenge, submitHumanResponse } from './human-responses.js'
+import type { Challenge } from './challenges.js'
+
+const testChallenge: Challenge = {
+  type: 'bitcoin_trivia',
+  label: 'Bitcoin Trivia',
+  prompt: 'What year was Bitcoin launched?',
+  answers: ['2009'],
+  scoring: 'factual',
+  timeout_ms: 8000,
+  difficulty: 'easy',
+  choices: ['2009', '2010', '2008'],
+}
+
+describe('waitForHumanResponse ordering', () => {
+  it('pending challenge is stored synchronously before promise is awaited', () => {
+    const fightId = `fight-ordering-${Date.now()}`
+    const botId = 'bot-ordering-test'
+
+    // Call waitForHumanResponse — the pending entry must be stored synchronously
+    const { promise, choices } = waitForHumanResponse(fightId, botId, testChallenge, 1)
+
+    // IMMEDIATELY check that getPendingChallenge returns data (before awaiting)
+    const pending = getPendingChallenge(fightId, botId)
+    expect(pending).not.toBeNull()
+    expect(pending!.prompt).toBe('What year was Bitcoin launched?')
+    expect(pending!.roundNumber).toBe(1)
+    expect(choices).toBeInstanceOf(Array)
+    expect(choices.length).toBe(3)
+
+    // Clean up: submit answer to resolve the promise
+    submitHumanResponse(fightId, botId, '2009')
+    // Consume promise to prevent unhandled rejection
+    return promise
+  })
+
+  it('choices returned by waitForHumanResponse match pending challenge choices', () => {
+    const fightId = `fight-choices-${Date.now()}`
+    const botId = 'bot-choices-test'
+
+    const { promise, choices } = waitForHumanResponse(fightId, botId, testChallenge, 2)
+
+    const pending = getPendingChallenge(fightId, botId)
+    expect(pending).not.toBeNull()
+    expect(pending!.choices).toEqual(choices)
+
+    submitHumanResponse(fightId, botId, '2009')
+    return promise
+  })
+
+  it('submitHumanResponse resolves the waiting promise', async () => {
+    const fightId = `fight-submit-${Date.now()}`
+    const botId = 'bot-submit-test'
+
+    const { promise } = waitForHumanResponse(fightId, botId, testChallenge, 3)
+
+    // Submit after a microtask delay to simulate browser response
+    setTimeout(() => submitHumanResponse(fightId, botId, '2009', 'nice!'), 10)
+
+    const result = await promise
+    expect(result.answer).toBe('2009')
+    expect(result.trashTalk).toBe('nice!')
+    expect(result.timedOut).toBe(false)
+  })
+
+  it('pending is cleared after submit', () => {
+    const fightId = `fight-clear-${Date.now()}`
+    const botId = 'bot-clear-test'
+
+    const { promise } = waitForHumanResponse(fightId, botId, testChallenge, 4)
+
+    submitHumanResponse(fightId, botId, '2009')
+
+    const pending = getPendingChallenge(fightId, botId)
+    expect(pending).toBeNull()
+
+    return promise
+  })
+})