feat: add @automaker/utils package

- Extract error handling utilities (isAbortError, classifyError, etc.)
- Extract conversation utilities (formatHistoryAsText, etc.)
- Extract image handling utilities (readImageAsBase64, etc.)
- Extract prompt building utilities (buildPromptWithImages)
- Extract logger utilities (createLogger, setLogLevel)
- Extract file system utilities (mkdirSafe, existsSafe)

All utilities now use @automaker/types for type imports.
Provides shared utility functions for both server and UI.

Dependencies: @automaker/types

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

libs/utils/src/conversation-utils.ts

@@ -0,0 +1,97 @@
+/**
+ * Conversation history utilities for processing message history
+ *
+ * Provides standardized conversation history handling:
+ * - Extract text from content (string or array format)
+ * - Normalize content blocks to array format
+ * - Format history as plain text for CLI-based providers
+ * - Convert history to Claude SDK message format
+ */
+
+import type { ConversationMessage } from '@automaker/types';
+
+/**
+ * Extract plain text from message content (handles both string and array formats)
+ *
+ * @param content - Message content (string or array of content blocks)
+ * @returns Extracted text content
+ */
+export function extractTextFromContent(
+  content: string | Array<{ type: string; text?: string; source?: object }>
+): string {
+  if (typeof content === "string") {
+    return content;
+  }
+
+  // Extract text blocks only
+  return content
+    .filter((block) => block.type === "text")
+    .map((block) => block.text || "")
+    .join("\n");
+}
+
+/**
+ * Normalize message content to array format
+ *
+ * @param content - Message content (string or array)
+ * @returns Content as array of blocks
+ */
+export function normalizeContentBlocks(
+  content: string | Array<{ type: string; text?: string; source?: object }>
+): Array<{ type: string; text?: string; source?: object }> {
+  if (Array.isArray(content)) {
+    return content;
+  }
+  return [{ type: "text", text: content }];
+}
+
+/**
+ * Format conversation history as plain text for CLI-based providers
+ *
+ * @param history - Array of conversation messages
+ * @returns Formatted text with role labels
+ */
+export function formatHistoryAsText(history: ConversationMessage[]): string {
+  if (history.length === 0) {
+    return "";
+  }
+
+  let historyText = "Previous conversation:\n\n";
+
+  for (const msg of history) {
+    const contentText = extractTextFromContent(msg.content);
+    const role = msg.role === "user" ? "User" : "Assistant";
+    historyText += `${role}: ${contentText}\n\n`;
+  }
+
+  historyText += "---\n\n";
+  return historyText;
+}
+
+/**
+ * Convert conversation history to Claude SDK message format
+ *
+ * @param history - Array of conversation messages
+ * @returns Array of Claude SDK formatted messages
+ */
+export function convertHistoryToMessages(
+  history: ConversationMessage[]
+): Array<{
+  type: "user" | "assistant";
+  session_id: string;
+  message: {
+    role: "user" | "assistant";
+    content: Array<{ type: string; text?: string; source?: object }>;
+  };
+  parent_tool_use_id: null;
+}> {
+  return history.map((historyMsg) => ({
+    type: historyMsg.role,
+    session_id: "",
+    message: {
+      role: historyMsg.role,
+      content: normalizeContentBlocks(historyMsg.content),
+    },
+    parent_tool_use_id: null,
+  }));
+}