diff --git a/changelog.d/fixes/pending-cc-cache-control-ttl-default.md b/changelog.d/fixes/pending-cc-cache-control-ttl-default.md
new file mode 100644
index 0000000000..0d89bee475
--- /dev/null
+++ b/changelog.d/fixes/pending-cc-cache-control-ttl-default.md
@@ -0,0 +1 @@
+- **fix(providers):** Claude Code / CC-protocol-compatible clients sending `cache_control` with no `ttl` on the native Claude OAuth path (`claude`/`cc`) now default to the 1h extended cache TTL instead of silently falling back to Anthropic's 5-minute default, even though the 1h beta is always negotiated on this path — thanks @jeff-alves
diff --git a/open-sse/executors/base.ts b/open-sse/executors/base.ts
index d1486263cb..8fe668b622 100644
--- a/open-sse/executors/base.ts
+++ b/open-sse/executors/base.ts
@@ -54,6 +54,7 @@ import {
 } from "../services/tokenRefresh.ts";
 import type { ProviderRequestDefaults } from "../services/providerRequestDefaults.ts";
 import { signRequestBody } from "../services/claudeCodeCCH.ts";
+import { normalizeCacheControlTtl } from "../services/claudeCodeConstraints.ts";
 import {
   appendAnthropicBetaHeader,
   CLAUDE_CODE_COMPATIBLE_REDACT_THINKING_BETA,
@@ -1118,6 +1119,7 @@ export class BaseExecutor {
           }
           sysBlocks.unshift({ type: "text", text: billingLine }, { type: "text", text: SENTINEL });
           tb.system = sysBlocks;
+          normalizeCacheControlTtl(tb);
 
           // Run the configurable system-transforms pipeline for the native
           // `claude` provider (issue #2260 / comment 4459544580). The default
diff --git a/open-sse/services/claudeCodeConstraints.ts b/open-sse/services/claudeCodeConstraints.ts
index ddac177b32..42ed52f996 100644
--- a/open-sse/services/claudeCodeConstraints.ts
+++ b/open-sse/services/claudeCodeConstraints.ts
@@ -7,6 +7,7 @@
  * 2. Disable thinking when tool_choice forces a specific tool
  * 3. Enforce max 4 cache_control breakpoints
  * 4. Normalize cache_control TTL ordering
+ * 5. Default missing cache_control.ttl to "1h" on the native Claude OAuth path
  */
 
 /**
@@ -156,3 +157,46 @@ export function ensureCacheControlOnLastUserMessage(body: Record<string, unknown
     }
   }
 }
+
+/**
+ * Real Claude Code (and CC-protocol-compatible clients) commonly send
+ * `cache_control: { type: "ephemeral" }` with no `ttl`. On the native Claude
+ * OAuth path the outbound anthropic-beta set always includes
+ * extended-cache-ttl-2025-04-11 (see ANTHROPIC_BETA_BASE /
+ * ANTHROPIC_BETA_CLAUDE_OAUTH in anthropicHeaders.ts), so requesting the 1h
+ * TTL is always valid here — but Anthropic only honors it when `ttl` is
+ * explicitly set; an absent `ttl` silently falls back to the platform
+ * default of 5 minutes even though the 1h beta was negotiated. Any pause
+ * longer than 5 minutes between turns then forces a full prefix rewrite
+ * instead of a cache hit. Default the ttl to "1h" wherever it's missing;
+ * never touch a cache_control that already specifies one (explicit client
+ * choice is preserved).
+ */
+export function normalizeCacheControlTtl(body: Record<string, unknown>): void {
+  const defaultMissingTtl = (block: Record<string, unknown> | null | undefined) => {
+    const cc = block?.cache_control as Record<string, unknown> | undefined;
+    if (cc && cc.type === "ephemeral" && cc.ttl === undefined) {
+      cc.ttl = "1h";
+    }
+  };
+
+  const system = body.system as Array<Record<string, unknown>> | undefined;
+  if (Array.isArray(system)) {
+    for (const block of system) defaultMissingTtl(block);
+  }
+
+  const tools = body.tools as Array<Record<string, unknown>> | undefined;
+  if (Array.isArray(tools)) {
+    for (const tool of tools) defaultMissingTtl(tool);
+  }
+
+  const messages = body.messages as Array<Record<string, unknown>> | undefined;
+  if (Array.isArray(messages)) {
+    for (const message of messages) {
+      const content = message.content as Array<Record<string, unknown>> | undefined;
+      if (Array.isArray(content)) {
+        for (const block of content) defaultMissingTtl(block);
+      }
+    }
+  }
+}
diff --git a/tests/unit/claude-code-parity.test.ts b/tests/unit/claude-code-parity.test.ts
index 480f76a177..0e58e9a3f3 100644
--- a/tests/unit/claude-code-parity.test.ts
+++ b/tests/unit/claude-code-parity.test.ts
@@ -34,6 +34,7 @@ import {
   disableThinkingIfToolChoiceForced,
   enforceCacheControlLimit,
   ensureCacheControlOnLastUserMessage,
+  normalizeCacheControlTtl,
 } from "../../open-sse/services/claudeCodeConstraints.ts";
 
 // ─────────────────────────────────────────────────────────────────────────────
@@ -401,3 +402,66 @@ describe("ensureCacheControlOnLastUserMessage", () => {
     assert.doesNotThrow(() => ensureCacheControlOnLastUserMessage({}));
   });
 });
+
+// ─────────────────────────────────────────────────────────────────────────────
+// normalizeCacheControlTtl tests
+// ─────────────────────────────────────────────────────────────────────────────
+
+describe("normalizeCacheControlTtl", () => {
+  it("defaults a missing ttl to 1h on the last system block", () => {
+    const body = {
+      system: [
+        { type: "text", text: "billing" },
+        { type: "text", text: "sentinel" },
+        { type: "text", text: "prompt", cache_control: { type: "ephemeral" } },
+      ],
+    };
+
+    normalizeCacheControlTtl(body);
+
+    assert.deepEqual(body.system[2].cache_control, { type: "ephemeral", ttl: "1h" });
+  });
+
+  it("does not touch a cache_control that already specifies a ttl", () => {
+    const body = {
+      system: [{ type: "text", text: "prompt", cache_control: { type: "ephemeral", ttl: "5m" } }],
+    };
+
+    normalizeCacheControlTtl(body);
+
+    assert.deepEqual(body.system[0].cache_control, { type: "ephemeral", ttl: "5m" });
+  });
+
+  it("defaults missing ttl in tools and message content blocks", () => {
+    const body = {
+      tools: [{ name: "bash", description: "run", cache_control: { type: "ephemeral" } }],
+      messages: [
+        {
+          role: "user",
+          content: [{ type: "text", text: "hi", cache_control: { type: "ephemeral" } }],
+        },
+      ],
+    };
+
+    normalizeCacheControlTtl(body);
+
+    assert.deepEqual(body.tools[0].cache_control, { type: "ephemeral", ttl: "1h" });
+    assert.deepEqual(body.messages[0].content[0].cache_control, {
+      type: "ephemeral",
+      ttl: "1h",
+    });
+  });
+
+  it("leaves blocks without cache_control untouched", () => {
+    const body = {
+      system: [{ type: "text", text: "no cache_control here" }],
+    };
+
+    assert.doesNotThrow(() => normalizeCacheControlTtl(body));
+    assert.equal(body.system[0].cache_control, undefined);
+  });
+
+  it("handles a body with no system/tools/messages without throwing", () => {
+    assert.doesNotThrow(() => normalizeCacheControlTtl({}));
+  });
+});