chore: initialize recovered claude workspace

src/utils/fingerprint.ts

@@ -0,0 +1,76 @@
+import { createHash } from 'crypto'
+import type { AssistantMessage, UserMessage } from '../types/message.js'
+
+/**
+ * Hardcoded salt from backend validation.
+ * Must match exactly for fingerprint validation to pass.
+ */
+export const FINGERPRINT_SALT = '59cf53e54c78'
+
+/**
+ * Extracts text content from the first user message.
+ *
+ * @param messages - Array of internal message types
+ * @returns First text content, or empty string if not found
+ */
+export function extractFirstMessageText(
+  messages: (UserMessage | AssistantMessage)[],
+): string {
+  const firstUserMessage = messages.find(msg => msg.type === 'user')
+  if (!firstUserMessage) {
+    return ''
+  }
+
+  const content = firstUserMessage.message.content
+
+  if (typeof content === 'string') {
+    return content
+  }
+
+  if (Array.isArray(content)) {
+    const textBlock = content.find(block => block.type === 'text')
+    if (textBlock && textBlock.type === 'text') {
+      return textBlock.text
+    }
+  }
+
+  return ''
+}
+
+/**
+ * Computes 3-character fingerprint for Claude Code attribution.
+ * Algorithm: SHA256(SALT + msg[4] + msg[7] + msg[20] + version)[:3]
+ * IMPORTANT: Do not change this method without careful coordination with
+ * 1P and 3P (Bedrock, Vertex, Azure) APIs.
+ *
+ * @param messageText - First user message text content
+ * @param version - Version string (from MACRO.VERSION)
+ * @returns 3-character hex fingerprint
+ */
+export function computeFingerprint(
+  messageText: string,
+  version: string,
+): string {
+  // Extract chars at indices [4, 7, 20], use "0" if index not found
+  const indices = [4, 7, 20]
+  const chars = indices.map(i => messageText[i] || '0').join('')
+
+  const fingerprintInput = `${FINGERPRINT_SALT}${chars}${version}`
+
+  // SHA256 hash, return first 3 hex chars
+  const hash = createHash('sha256').update(fingerprintInput).digest('hex')
+  return hash.slice(0, 3)
+}
+
+/**
+ * Computes fingerprint from the first user message.
+ *
+ * @param messages - Array of normalized messages
+ * @returns 3-character hex fingerprint
+ */
+export function computeFingerprintFromMessages(
+  messages: (UserMessage | AssistantMessage)[],
+): string {
+  const firstMessageText = extractFirstMessageText(messages)
+  return computeFingerprint(firstMessageText, MACRO.VERSION)
+}