diff --git a/docs/reference/prompt-caching.md b/docs/reference/prompt-caching.md
index f4c784bde731..f792298a0f8a 100644
--- a/docs/reference/prompt-caching.md
+++ b/docs/reference/prompt-caching.md
@@ -21,6 +21,7 @@ Provider references:
 ### `cacheRetention`
 
 Values: `"none" | "short" | "long"`. Configurable as a global default, per model, and per agent.
+`"standard"` is not an alias; use `"short"` for the provider's default cache window. Invalid values are ignored with a warning.
 
 ```yaml
 agents:
diff --git a/src/agents/embedded-agent-runner/extra-params.cache-retention-default.test.ts b/src/agents/embedded-agent-runner/extra-params.cache-retention-default.test.ts
index 93ec35d468cc..07d4e86894d6 100644
--- a/src/agents/embedded-agent-runner/extra-params.cache-retention-default.test.ts
+++ b/src/agents/embedded-agent-runner/extra-params.cache-retention-default.test.ts
@@ -3,6 +3,7 @@ import type { StreamFn } from "openclaw/plugin-sdk/agent-core";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { createLlmStreamSimpleMock } from "../../../test/helpers/agents/llm-stream-simple-mock.js";
 import { testing as extraParamsTesting, applyExtraParamsToAgent } from "./extra-params.js";
+import { log } from "./logger.js";
 import { resolveCacheRetention } from "./prompt-cache-retention.js";
 
 function applyAndExpectWrapped(params: {
@@ -44,6 +45,7 @@ vi.mock("./logger.js", () => ({
 vi.mock("../../llm/stream.js", () => createLlmStreamSimpleMock());
 
 beforeEach(() => {
+  vi.mocked(log.warn).mockClear();
   extraParamsTesting.setProviderRuntimeDepsForTest({
     prepareProviderExtraParams: () => undefined,
     resolveProviderExtraParamsForTransport: () => undefined,
@@ -257,6 +259,30 @@ describe("cacheRetention default behavior", () => {
     ).toBe("long");
   });
 
+  it("warns instead of creating an undocumented cacheRetention alias", () => {
+    applyAndExpectWrapped({
+      cfg: {
+        agents: {
+          defaults: {
+            models: {
+              "amazon-bedrock/us.anthropic.claude-sonnet-4-6": {
+                params: { cacheRetention: "standard" },
+              },
+            },
+          },
+        },
+      },
+      modelId: "us.anthropic.claude-sonnet-4-6",
+      model: { api: "openai-completions" } as Parameters<typeof applyExtraParamsToAgent>[8],
+      provider: "amazon-bedrock",
+    });
+
+    expect(log.warn).toHaveBeenCalledOnce();
+    expect(log.warn).toHaveBeenCalledWith(
+      'ignoring invalid cacheRetention param; expected "none", "short", or "long"',
+    );
+  });
+
   it("defaults to 'short' for anthropic-vertex without explicit config", () => {
     expect(
       resolveCacheRetention(
diff --git a/src/agents/embedded-agent-runner/extra-params.ts b/src/agents/embedded-agent-runner/extra-params.ts
index 0b217d82f15a..6b9dc44bd2d6 100644
--- a/src/agents/embedded-agent-runner/extra-params.ts
+++ b/src/agents/embedded-agent-runner/extra-params.ts
@@ -42,7 +42,7 @@ import type { AgentRuntimeTransport } from "../runtime-plan/types.js";
 import type { StreamFn } from "../runtime/index.js";
 import type { SettingsManager } from "../sessions/index.js";
 import { log } from "./logger.js";
-import { resolveCacheRetention } from "./prompt-cache-retention.js";
+import { parseCacheRetention, resolveCacheRetention } from "./prompt-cache-retention.js";
 import type { ProviderThinkLevel } from "./utils.js";
 
 const defaultProviderRuntimeDeps = {
@@ -452,6 +452,15 @@ function createStreamFnWithExtraParams(
     return undefined;
   }
 
+  if (
+    Object.hasOwn(extraParams, "cacheRetention") &&
+    parseCacheRetention(extraParams.cacheRetention) === undefined
+  ) {
+    // Provider params stay open-ended, so validate this shared knob at its consumer boundary.
+    // Never echo the authored value: model params can contain sensitive custom data.
+    log.warn('ignoring invalid cacheRetention param; expected "none", "short", or "long"');
+  }
+
   const streamParams: CacheRetentionStreamOptions = {};
   if (typeof extraParams.temperature === "number") {
     streamParams.temperature = extraParams.temperature;
diff --git a/src/agents/embedded-agent-runner/prompt-cache-retention.test.ts b/src/agents/embedded-agent-runner/prompt-cache-retention.test.ts
index 11d1490525bb..dde8018ff7f2 100644
--- a/src/agents/embedded-agent-runner/prompt-cache-retention.test.ts
+++ b/src/agents/embedded-agent-runner/prompt-cache-retention.test.ts
@@ -63,6 +63,17 @@ describe("prompt cache retention", () => {
     ).toBe("none");
   });
 
+  it("keeps undocumented cacheRetention values outside the Bedrock runtime contract", () => {
+    expect(
+      resolveCacheRetention(
+        { cacheRetention: "standard" },
+        "amazon-bedrock",
+        "openai-completions",
+        "us.anthropic.claude-sonnet-4-6",
+      ),
+    ).toBeUndefined();
+  });
+
   it("does not honor explicit cacheRetention for openai-completions without supportsPromptCacheKey", () => {
     // Providers that route via openai-completions but do not advertise prompt
     // caching must keep retention out of outgoing payloads.
diff --git a/src/agents/embedded-agent-runner/prompt-cache-retention.ts b/src/agents/embedded-agent-runner/prompt-cache-retention.ts
index 1bcbbc246a49..760f43347e40 100644
--- a/src/agents/embedded-agent-runner/prompt-cache-retention.ts
+++ b/src/agents/embedded-agent-runner/prompt-cache-retention.ts
@@ -6,6 +6,10 @@ import { resolveAnthropicCacheRetentionFamily } from "../../llm/providers/stream
 
 type CacheRetention = "none" | "short" | "long";
 
+export function parseCacheRetention(value: unknown): CacheRetention | undefined {
+  return value === "none" || value === "short" || value === "long" ? value : undefined;
+}
+
 export function isGooglePromptCacheEligible(params: {
   modelApi?: string;
   modelId?: string;
@@ -46,8 +50,8 @@ export function resolveCacheRetention(
     return undefined;
   }
 
-  const newVal = extraParams?.cacheRetention;
-  if (newVal === "none" || newVal === "short" || newVal === "long") {
+  const newVal = parseCacheRetention(extraParams?.cacheRetention);
+  if (newVal) {
     return newVal;
   }