diff --git a/src/dedup.test.ts b/src/dedup.test.ts
new file mode 100644
index 00000000..59ea9635
--- /dev/null
+++ b/src/dedup.test.ts
@@ -0,0 +1,109 @@
+import { describe, it, expect } from "vitest";
+import { RequestDeduplicator } from "./dedup.js";
+
+describe("RequestDeduplicator.hash", () => {
+  it("produces the same key for retries that only differ by injected timestamp (string content)", () => {
+    const body1 = Buffer.from(
+      JSON.stringify({
+        model: "blockrun/auto",
+        messages: [{ role: "user", content: "[Mon 2024-01-15 10:30 PST] hello" }],
+      }),
+    );
+    const body2 = Buffer.from(
+      JSON.stringify({
+        model: "blockrun/auto",
+        messages: [{ role: "user", content: "[Mon 2024-01-15 10:31 PST] hello" }],
+      }),
+    );
+
+    expect(RequestDeduplicator.hash(body1)).toBe(RequestDeduplicator.hash(body2));
+  });
+
+  it("produces the same key for retries of Anthropic-style array content blocks", () => {
+    // Vision/multimodal messages send content as [{type: "text", text}, {type: "image_url", ...}]
+    // instead of a plain string. OpenClaw injects a fresh timestamp into the leading text
+    // block on every retry — without stripping it there, a timed-out request that gets
+    // retried never dedupes against the original and can be paid for twice.
+    const body1 = Buffer.from(
+      JSON.stringify({
+        model: "blockrun/auto",
+        messages: [
+          {
+            role: "user",
+            content: [
+              { type: "text", text: "[Mon 2024-01-15 10:30 PST] what's in this image?" },
+              { type: "image_url", image_url: { url: "https://example.com/a.png" } },
+            ],
+          },
+        ],
+      }),
+    );
+    const body2 = Buffer.from(
+      JSON.stringify({
+        model: "blockrun/auto",
+        messages: [
+          {
+            role: "user",
+            content: [
+              { type: "text", text: "[Mon 2024-01-15 10:31 PST] what's in this image?" },
+              { type: "image_url", image_url: { url: "https://example.com/a.png" } },
+            ],
+          },
+        ],
+      }),
+    );
+
+    expect(RequestDeduplicator.hash(body1)).toBe(RequestDeduplicator.hash(body2));
+  });
+
+  it("preserves timestamp-shaped prefixes in non-leading text blocks (user data, not injected)", () => {
+    // OpenClaw only injects into the FIRST text block. A bracketed timestamp at the
+    // start of a later text block is the user's own content (e.g. a pasted log line) —
+    // stripping it would make two genuinely different requests collide on one key,
+    // wrongly deduping a distinct paid request.
+    const mk = (day: string) =>
+      Buffer.from(
+        JSON.stringify({
+          model: "blockrun/auto",
+          messages: [
+            {
+              role: "user",
+              content: [
+                { type: "text", text: "[Mon 2024-01-15 10:30 PST] explain this log line" },
+                { type: "text", text: `[${day} 2024-01-16 09:15 UTC] connection refused` },
+              ],
+            },
+          ],
+        }),
+      );
+
+    expect(RequestDeduplicator.hash(mk("Tue"))).not.toBe(RequestDeduplicator.hash(mk("Wed")));
+  });
+
+  it("still produces different keys when array content actually differs", () => {
+    const body1 = Buffer.from(
+      JSON.stringify({
+        model: "blockrun/auto",
+        messages: [
+          {
+            role: "user",
+            content: [{ type: "text", text: "[Mon 2024-01-15 10:30 PST] describe image A" }],
+          },
+        ],
+      }),
+    );
+    const body2 = Buffer.from(
+      JSON.stringify({
+        model: "blockrun/auto",
+        messages: [
+          {
+            role: "user",
+            content: [{ type: "text", text: "[Mon 2024-01-15 10:30 PST] describe image B" }],
+          },
+        ],
+      }),
+    );
+
+    expect(RequestDeduplicator.hash(body1)).not.toBe(RequestDeduplicator.hash(body2));
+  });
+});
diff --git a/src/dedup.ts b/src/dedup.ts
index b6b0aa12..7bb942b6 100644
--- a/src/dedup.ts
+++ b/src/dedup.ts
@@ -7,6 +7,8 @@
 
 import { createHash } from "node:crypto";
 
+import { TIMESTAMP_PATTERN, stripLeadingTextBlockTimestamp } from "./timestamp-strip.js";
+
 export type CachedResponse = {
   status: number;
   headers: Record<string, string>;
@@ -46,8 +48,6 @@ function canonicalize(obj: unknown): unknown {
  *
  * This ensures requests with different timestamps but same content hash identically.
  */
-const TIMESTAMP_PATTERN = /^\[\w{3}\s+\d{4}-\d{2}-\d{2}\s+\d{2}:\d{2}\s+\w+\]\s*/;
-
 function stripTimestamps(obj: unknown): unknown {
   if (obj === null || typeof obj !== "object") {
     return obj;
@@ -58,8 +58,16 @@ function stripTimestamps(obj: unknown): unknown {
   const result: Record<string, unknown> = {};
   for (const [key, value] of Object.entries(obj as Record<string, unknown>)) {
     if (key === "content" && typeof value === "string") {
-      // Strip timestamp prefix from message content
+      // Strip timestamp prefix from plain-string message content
       result[key] = value.replace(TIMESTAMP_PATTERN, "");
+    } else if (key === "content" && Array.isArray(value)) {
+      // Anthropic-style content blocks (e.g. [{type: "text", text: "..."}, {type: "image_url", ...}]).
+      // OpenClaw injects its timestamp into the FIRST text block only — the plain-string
+      // branch above never fires for these, so without this the injected timestamp stays
+      // in the hash input and breaks dedup on every retry of a multimodal message.
+      // Later text blocks are user data; a bracketed timestamp there must be preserved
+      // so genuinely different requests keep different keys.
+      result[key] = stripLeadingTextBlockTimestamp(value.map(stripTimestamps));
     } else {
       result[key] = stripTimestamps(value);
     }
diff --git a/src/response-cache.test.ts b/src/response-cache.test.ts
index baa8db4a..cf880882 100644
--- a/src/response-cache.test.ts
+++ b/src/response-cache.test.ts
@@ -79,6 +79,77 @@ describe("ResponseCache", () => {
       expect(ResponseCache.generateKey(body1)).toBe(ResponseCache.generateKey(body2));
     });
 
+    it("should strip timestamps from Anthropic-style array content blocks", () => {
+      // Multimodal/vision messages use content: [{type: "text", text}, ...] instead
+      // of a plain string. A retried request gets a fresh injected timestamp on the
+      // leading text block each time — the key must still match or every retry of a
+      // vision message misses the cache and gets billed as a brand-new request.
+      const body1 = JSON.stringify({
+        model: "gpt-4",
+        messages: [
+          {
+            role: "user",
+            content: [
+              { type: "text", text: "[Mon 2024-01-15 10:30 PST] describe this" },
+              { type: "image_url", image_url: { url: "https://example.com/a.png" } },
+            ],
+          },
+        ],
+      });
+      const body2 = JSON.stringify({
+        model: "gpt-4",
+        messages: [
+          {
+            role: "user",
+            content: [
+              { type: "text", text: "[Mon 2024-01-15 10:31 PST] describe this" },
+              { type: "image_url", image_url: { url: "https://example.com/a.png" } },
+            ],
+          },
+        ],
+      });
+
+      expect(ResponseCache.generateKey(body1)).toBe(ResponseCache.generateKey(body2));
+    });
+
+    it("should preserve timestamp-shaped prefixes in non-leading text blocks", () => {
+      // Only the first text block carries the injected timestamp; a bracketed
+      // timestamp starting a later block is user data. Stripping it would give two
+      // different requests the same cache key and serve the wrong cached response.
+      const mk = (day: string) =>
+        JSON.stringify({
+          model: "gpt-4",
+          messages: [
+            {
+              role: "user",
+              content: [
+                { type: "text", text: "[Mon 2024-01-15 10:30 PST] explain this log line" },
+                { type: "text", text: `[${day} 2024-01-16 09:15 UTC] connection refused` },
+              ],
+            },
+          ],
+        });
+
+      expect(ResponseCache.generateKey(mk("Tue"))).not.toBe(ResponseCache.generateKey(mk("Wed")));
+    });
+
+    it("should generate different keys when array content actually differs", () => {
+      const mk = (text: string) =>
+        JSON.stringify({
+          model: "gpt-4",
+          messages: [
+            {
+              role: "user",
+              content: [{ type: "text", text: `[Mon 2024-01-15 10:30 PST] ${text}` }],
+            },
+          ],
+        });
+
+      expect(ResponseCache.generateKey(mk("describe image A"))).not.toBe(
+        ResponseCache.generateKey(mk("describe image B")),
+      );
+    });
+
     it("should handle Buffer input", () => {
       const body = Buffer.from(
         JSON.stringify({
diff --git a/src/response-cache.ts b/src/response-cache.ts
index 6e24b25f..4447b7d3 100644
--- a/src/response-cache.ts
+++ b/src/response-cache.ts
@@ -14,6 +14,8 @@
 
 import { createHash } from "node:crypto";
 
+import { TIMESTAMP_PATTERN, stripLeadingTextBlockTimestamp } from "./timestamp-strip.js";
+
 export type CachedLLMResponse = {
   body: Buffer;
   status: number;
@@ -70,8 +72,6 @@ function canonicalize(obj: unknown): unknown {
  * separate cache slots — otherwise the first one's response is served to the
  * second, which breaks the client.
  */
-const TIMESTAMP_PATTERN = /^\[\w{3}\s+\d{4}-\d{2}-\d{2}\s+\d{2}:\d{2}\s+\w+\]\s*/;
-
 function normalizeForCache(obj: Record<string, unknown>): Record<string, unknown> {
   const result: Record<string, unknown> = {};
 
@@ -89,6 +89,15 @@ function normalizeForCache(obj: Record<string, unknown>): Record<string, unknown
           if (typeof m.content === "string") {
             return { ...m, content: m.content.replace(TIMESTAMP_PATTERN, "") };
           }
+          if (Array.isArray(m.content)) {
+            // Anthropic-style content blocks — the injected timestamp lives in the
+            // FIRST text block's `text` field. Without this, a retried multimodal
+            // message (vision, image attachments) gets a fresh injected timestamp
+            // each time and never hits the cache, so it's billed as a brand-new
+            // request. Later text blocks are user data and are left untouched so
+            // genuinely different requests keep different cache keys.
+            return { ...m, content: stripLeadingTextBlockTimestamp(m.content) };
+          }
         }
         return msg;
       });
diff --git a/src/timestamp-strip.ts b/src/timestamp-strip.ts
new file mode 100644
index 00000000..7fe785ab
--- /dev/null
+++ b/src/timestamp-strip.ts
@@ -0,0 +1,35 @@
+/**
+ * OpenClaw-injected timestamp stripping, shared by the request deduplicator
+ * and the response cache so their key normalization cannot drift apart.
+ *
+ * OpenClaw injects a fresh [DAY YYYY-MM-DD HH:MM TZ] prefix on every request:
+ * for plain-string content it is prepended to the string, and for array-form
+ * (multimodal) content it lands in the FIRST text block only. Later text
+ * blocks never carry an injected stamp — a bracketed timestamp there is the
+ * user's own data (e.g. a pasted log line) and must be preserved, otherwise
+ * two genuinely different requests collide on the same key and the wrong
+ * cached response is served (or a distinct paid request is wrongly deduped).
+ */
+export const TIMESTAMP_PATTERN = /^\[\w{3}\s+\d{4}-\d{2}-\d{2}\s+\d{2}:\d{2}\s+\w+\]\s*/;
+
+/**
+ * Strip the injected timestamp prefix from the first text block of an
+ * array-form content value. All other blocks are returned unchanged.
+ */
+export function stripLeadingTextBlockTimestamp(blocks: unknown[]): unknown[] {
+  let stripped = false;
+  return blocks.map((block) => {
+    if (
+      !stripped &&
+      block !== null &&
+      typeof block === "object" &&
+      (block as { type?: unknown }).type === "text" &&
+      typeof (block as { text?: unknown }).text === "string"
+    ) {
+      stripped = true;
+      const b = block as { text: string };
+      return { ...b, text: b.text.replace(TIMESTAMP_PATTERN, "") };
+    }
+    return block;
+  });
+}