feat: activate buddy system in open build (#346)

src/buddy/observer.ts

@@ -0,0 +1,65 @@
+import type { Message } from '../types/message.js'
+import { getGlobalConfig } from '../utils/config.js'
+import { getUserMessageText } from '../utils/messages.js'
+import { getCompanion } from './companion.js'
+
+const DIRECT_REPLIES = [
+  'I am observing.',
+  'I am helping from the corner.',
+  'I saw that.',
+  'Still here.',
+  'Watching closely.',
+] as const
+
+const PET_REPLIES = [
+  'happy chirp',
+  'tiny victory dance',
+  'quietly approves',
+  'wiggles with joy',
+  'looks pleased',
+] as const
+
+function hashString(s: string): number {
+  let h = 2166136261
+  for (let i = 0; i < s.length; i++) {
+    h ^= s.charCodeAt(i)
+    h = Math.imul(h, 16777619)
+  }
+  return h >>> 0
+}
+
+function pickDeterministic<T>(items: readonly T[], seed: string): T {
+  return items[hashString(seed) % items.length]!
+}
+
+export async function fireCompanionObserver(
+  messages: Message[],
+  onReaction: (reaction: string | undefined) => void,
+): Promise<void> {
+  const companion = getCompanion()
+  if (!companion || getGlobalConfig().companionMuted) return
+
+  const lastUser = [...messages].reverse().find(msg => msg.type === 'user')
+  if (!lastUser) return
+
+  const text = getUserMessageText(lastUser)?.trim()
+  if (!text) return
+
+  const lower = text.toLowerCase()
+  const companionName = companion.name.toLowerCase()
+
+  if (lower.includes('/buddy')) {
+    onReaction(pickDeterministic(PET_REPLIES, text + companion.name))
+    return
+  }
+
+  if (
+    lower.includes(companionName) ||
+    lower.includes('buddy') ||
+    lower.includes('companion')
+  ) {
+    onReaction(
+      `${companion.name}: ${pickDeterministic(DIRECT_REPLIES, text + companion.personality)}`,
+    )
+  }
+}