diff --git a/mateclaw-server/src/main/java/vip/mate/agent/AgentGraphBuilder.java b/mateclaw-server/src/main/java/vip/mate/agent/AgentGraphBuilder.java
index 36065c9b..7bd8c9a8 100644
--- a/mateclaw-server/src/main/java/vip/mate/agent/AgentGraphBuilder.java
+++ b/mateclaw-server/src/main/java/vip/mate/agent/AgentGraphBuilder.java
@@ -1320,6 +1320,23 @@ public class AgentGraphBuilder {
 
     // ==================== Prompt 构建 ====================
 
+    /**
+     * Cache-stable platform identity, appended to every agent's system
+     * prompt. Answers "who are you / what are you based on". The volatile
+     * "which model right now" fact is injected per-turn by
+     * {@link vip.mate.agent.context.RuntimeContextInjector} instead, to
+     * keep this prefix's prompt-cache hash stable.
+     */
+    static final String ABOUT_YOU_BLOCK = """
+
+            ## About You
+            You are powered by MateClaw — a multi-user AI Agent platform built on
+            Spring Boot 3.5 and Spring AI Alibaba Graph. You are reachable through
+            WebChat and 8+ IM channels (DingTalk, Feishu, WeCom, WeChat, Telegram,
+            Discord, QQ, Slack). If asked who you are or what you are based on,
+            answer with MateClaw and the technology stack above.
+            """;
+
     private String buildEnhancedPrompt(AgentEntity entity, boolean builtinSearchEnabled) {
         // The agent's own systemPrompt encodes its identity (role / goal /
         // backstory). The memory block from workspace files (AGENTS.md, SOUL.md,
@@ -1475,7 +1492,7 @@ public class AgentGraphBuilder {
         // Wiki 知识库上下文注入
         String wikiContext = wikiContextService.buildWikiContext(entity.getId());
 
-        return basePrompt + toolGuidance + searchGuidance + wikiContext;
+        return basePrompt + ABOUT_YOU_BLOCK + toolGuidance + searchGuidance + wikiContext;
     }
 
     /**
diff --git a/mateclaw-server/src/test/java/vip/mate/agent/AgentGraphBuilderIdentityBlockTest.java b/mateclaw-server/src/test/java/vip/mate/agent/AgentGraphBuilderIdentityBlockTest.java
new file mode 100644
index 00000000..7e4dcfea
--- /dev/null
+++ b/mateclaw-server/src/test/java/vip/mate/agent/AgentGraphBuilderIdentityBlockTest.java
@@ -0,0 +1,25 @@
+package vip.mate.agent;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Pin the static "## About You" identity block appended to every agent's
+ * system prompt. This is the cache-stable half of the self-introspection
+ * feature — it answers "who are you / what are you based on", while the
+ * volatile model line lives in RuntimeContextInjector.
+ */
+class AgentGraphBuilderIdentityBlockTest {
+
+    @Test
+    @DisplayName("identity block names MateClaw and the core tech stack")
+    void identityBlockMentionsPlatformAndStack() {
+        String block = AgentGraphBuilder.ABOUT_YOU_BLOCK;
+
+        assertTrue(block.contains("## About You"), "missing heading: " + block);
+        assertTrue(block.contains("MateClaw"), "must name the platform: " + block);
+        assertTrue(block.contains("Spring AI Alibaba Graph"), "must name the graph runtime: " + block);
+    }
+}