refactor(agents): share turn validation skeleton

src/agents/pi-embedded-helpers/turns.ts

@@ -1,11 +1,14 @@
 import type { AgentMessage } from "@mariozechner/pi-agent-core";
 
-/**
- * Validates and fixes conversation turn sequences for Gemini API.
- * Gemini requires strict alternating user→assistant→tool→user pattern.
- * Merges consecutive assistant messages together.
- */
-export function validateGeminiTurns(messages: AgentMessage[]): AgentMessage[] {
+function validateTurnsWithConsecutiveMerge<TRole extends "assistant" | "user">(params: {
+  messages: AgentMessage[];
+  role: TRole;
+  merge: (
+    previous: Extract<AgentMessage, { role: TRole }>,
+    current: Extract<AgentMessage, { role: TRole }>,
+  ) => Extract<AgentMessage, { role: TRole }>;
+}): AgentMessage[] {
+  const { messages, role, merge } = params;
   if (!Array.isArray(messages) || messages.length === 0) {
     return messages;
   }
@@ -25,28 +28,13 @@ export function validateGeminiTurns(messages: AgentMessage[]): AgentMessage[] {
       continue;
     }
 
-    if (msgRole === lastRole && lastRole === "assistant") {
+    if (msgRole === lastRole && lastRole === role) {
       const lastMsg = result[result.length - 1];
-      const currentMsg = msg as Extract<AgentMessage, { role: "assistant" }>;
+      const currentMsg = msg as Extract<AgentMessage, { role: TRole }>;
 
       if (lastMsg && typeof lastMsg === "object") {
-        const lastAsst = lastMsg as Extract<AgentMessage, { role: "assistant" }>;
-        const mergedContent = [
-          ...(Array.isArray(lastAsst.content) ? lastAsst.content : []),
-          ...(Array.isArray(currentMsg.content) ? currentMsg.content : []),
-        ];
-
-        const merged: Extract<AgentMessage, { role: "assistant" }> = {
-          ...lastAsst,
-          content: mergedContent,
-          ...(currentMsg.usage && { usage: currentMsg.usage }),
-          ...(currentMsg.stopReason && { stopReason: currentMsg.stopReason }),
-          ...(currentMsg.errorMessage && {
-            errorMessage: currentMsg.errorMessage,
-          }),
-        };
-
-        result[result.length - 1] = merged;
+        const lastTyped = lastMsg as Extract<AgentMessage, { role: TRole }>;
+        result[result.length - 1] = merge(lastTyped, currentMsg);
         continue;
       }
     }
@@ -58,6 +46,38 @@ export function validateGeminiTurns(messages: AgentMessage[]): AgentMessage[] {
   return result;
 }
 
+function mergeConsecutiveAssistantTurns(
+  previous: Extract<AgentMessage, { role: "assistant" }>,
+  current: Extract<AgentMessage, { role: "assistant" }>,
+): Extract<AgentMessage, { role: "assistant" }> {
+  const mergedContent = [
+    ...(Array.isArray(previous.content) ? previous.content : []),
+    ...(Array.isArray(current.content) ? current.content : []),
+  ];
+  return {
+    ...previous,
+    content: mergedContent,
+    ...(current.usage && { usage: current.usage }),
+    ...(current.stopReason && { stopReason: current.stopReason }),
+    ...(current.errorMessage && {
+      errorMessage: current.errorMessage,
+    }),
+  };
+}
+
+/**
+ * Validates and fixes conversation turn sequences for Gemini API.
+ * Gemini requires strict alternating user→assistant→tool→user pattern.
+ * Merges consecutive assistant messages together.
+ */
+export function validateGeminiTurns(messages: AgentMessage[]): AgentMessage[] {
+  return validateTurnsWithConsecutiveMerge({
+    messages,
+    role: "assistant",
+    merge: mergeConsecutiveAssistantTurns,
+  });
+}
+
 export function mergeConsecutiveUserTurns(
   previous: Extract<AgentMessage, { role: "user" }>,
   current: Extract<AgentMessage, { role: "user" }>,
@@ -80,40 +100,9 @@ export function mergeConsecutiveUserTurns(
  * Merges consecutive user messages together.
  */
 export function validateAnthropicTurns(messages: AgentMessage[]): AgentMessage[] {
-  if (!Array.isArray(messages) || messages.length === 0) {
-    return messages;
-  }
-
-  const result: AgentMessage[] = [];
-  let lastRole: string | undefined;
-
-  for (const msg of messages) {
-    if (!msg || typeof msg !== "object") {
-      result.push(msg);
-      continue;
-    }
-
-    const msgRole = (msg as { role?: unknown }).role as string | undefined;
-    if (!msgRole) {
-      result.push(msg);
-      continue;
-    }
-
-    if (msgRole === lastRole && lastRole === "user") {
-      const lastMsg = result[result.length - 1];
-      const currentMsg = msg as Extract<AgentMessage, { role: "user" }>;
-
-      if (lastMsg && typeof lastMsg === "object") {
-        const lastUser = lastMsg as Extract<AgentMessage, { role: "user" }>;
-        const merged = mergeConsecutiveUserTurns(lastUser, currentMsg);
-        result[result.length - 1] = merged;
-        continue;
-      }
-    }
-
-    result.push(msg);
-    lastRole = msgRole;
-  }
-
-  return result;
+  return validateTurnsWithConsecutiveMerge({
+    messages,
+    role: "user",
+    merge: mergeConsecutiveUserTurns,
+  });
 }