fix: include user message in auto-capture when prePromptMessageCount excludes it

Closes #1248

When OpenClaw's prePromptMessageCount points to an index that excludes
the current turn's user message, the VLM extractor receives only
assistant-role text (a recap/acknowledgment), yielding 0 extractable
memories.

This adds an ensureLastUserMessage parameter to extractNewTurnTexts.
When true, if no user message appears in the extracted window, the
last user message in the transcript is prepended to results.

Adapted from the original PR (#1256) which targeted the now-renamed
openclaw-memory-plugin directory.

Author: wzrrrrrrr

examples/openclaw-plugin/context-engine.ts

@@ -806,7 +806,7 @@ export function createMemoryOpenVikingContextEngine(params: {
             ? afterTurnParams.prePromptMessageCount
             : 0;
 
-        const { texts: newTexts, newCount } = extractNewTurnTexts(messages, start);
+        const { texts: newTexts, newCount } = extractNewTurnTexts(messages, start, true);
 
         if (newTexts.length === 0) {
           diag("afterTurn_skip", OVSessionId, {

examples/openclaw-plugin/text-utils.ts

@@ -419,6 +419,7 @@ function formatToolResultContent(content: unknown): string {
 export function extractNewTurnTexts(
   messages: unknown[],
   startIndex: number,
+  ensureLastUserMessage?: boolean,
 ): { texts: string[]; newCount: number } {
   const texts: string[] = [];
   let count = 0;
@@ -452,6 +453,36 @@ export function extractNewTurnTexts(
       }
     }
   }
+  // Defensive fix: ensure the last user message is included even if
+  // startIndex skipped it (OpenClaw prePromptMessageCount off-by-one)
+  // See: https://github.com/volcengine/OpenViking/issues/1248
+  if (ensureLastUserMessage && messages.length > 0) {
+    let lastUserText: string | null = null;
+    for (let i = messages.length - 1; i >= 0; i--) {
+      const msg = messages[i] as Record<string, unknown>;
+      if (!msg || typeof msg !== "object") continue;
+      if (msg.role === "user") {
+        const content = msg.content;
+        if (typeof content === "string" && content.trim()) {
+          lastUserText = `[user]: ${content.trim()}`;
+        } else if (Array.isArray(content)) {
+          for (const block of content) {
+            const b = block as Record<string, unknown>;
+            if (b?.type === "text" && typeof b.text === "string" && b.text.trim()) {
+              lastUserText = `[user]: ${b.text.trim()}`;
+              break;
+            }
+          }
+        }
+        break;
+      }
+    }
+    if (lastUserText && !texts.some((t) => t.startsWith("[user]:"))) {
+      texts.unshift(lastUserText);
+      count++;
+    }
+  }
+
   return { texts, newCount: count };
 }