diff --git a/CHANGELOG.md b/CHANGELOG.md
index ae4fe623545..c110e2f612f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -56,6 +56,7 @@ Docs: https://docs.openclaw.ai
 - Signal/Install: auto-install `signal-cli` via Homebrew on non-x64 Linux architectures, avoiding x86_64 native binary `Exec format error` failures on arm64/arm hosts. (#15443) Thanks @jogvan-k.
 - Discord: avoid misrouting numeric guild allowlist entries to `/channels/<guildId>` by prefixing guild-only inputs with `guild:` during resolution. (#12326) Thanks @headswim.
 - Config: preserve `${VAR}` env references when writing config files so `openclaw config set/apply/patch` does not persist secrets to disk. Thanks @thewilloftheshadow.
+- Config: log overwrite audit entries (path, backup target, and hash transition) whenever an existing config file is replaced, improving traceability for unexpected config clobbers.
 - Process/Exec: avoid shell execution for `.exe` commands on Windows so env overrides work reliably in `runCommandWithTimeout`. Thanks @thewilloftheshadow.
 - Web tools/web_fetch: prefer `text/markdown` responses for Cloudflare Markdown for Agents, add `cf-markdown` extraction for markdown bodies, and redact fetched URLs in `x-markdown-tokens` debug logs to avoid leaking raw paths/query params. (#15376) Thanks @Yaxuan42.
 - Config: keep legacy audio transcription migration strict by rejecting non-string/unsafe command tokens while still migrating valid custom script executables. (#5042) Thanks @shayan919293.
diff --git a/src/config/io.ts b/src/config/io.ts
index 184f73942aa..26d812d1469 100644
--- a/src/config/io.ts
+++ b/src/config/io.ts
@@ -725,6 +725,19 @@ export function createConfigIO(overrides: ConfigIoDeps = {}) {
     // Do NOT apply runtime defaults when writing — user config should only contain
     // explicitly set values. Runtime defaults are applied when loading (issue #6070).
     const json = JSON.stringify(stampConfigVersion(outputConfig), null, 2).trimEnd().concat("\n");
+    const nextHash = hashConfigRaw(json);
+    const previousHash = resolveConfigSnapshotHash(snapshot);
+    const changedPathCount = changedPaths?.size;
+    const logConfigOverwrite = () => {
+      if (!snapshot.exists) {
+        return;
+      }
+      const changeSummary =
+        typeof changedPathCount === "number" ? `, changedPaths=${changedPathCount}` : "";
+      deps.logger.warn(
+        `Config overwrite: ${configPath} (sha256 ${previousHash ?? "unknown"} -> ${nextHash}, backup=${configPath}.bak${changeSummary})`,
+      );
+    };
 
     const tmp = path.join(
       dir,
@@ -756,6 +769,7 @@ export function createConfigIO(overrides: ConfigIoDeps = {}) {
         await deps.fs.promises.unlink(tmp).catch(() => {
           // best-effort
         });
+        logConfigOverwrite();
         return;
       }
       await deps.fs.promises.unlink(tmp).catch(() => {
@@ -763,6 +777,7 @@ export function createConfigIO(overrides: ConfigIoDeps = {}) {
       });
       throw err;
     }
+    logConfigOverwrite();
   }
 
   return {
diff --git a/src/config/io.write-config.test.ts b/src/config/io.write-config.test.ts
index 2aa85b20d46..917a3f3f009 100644
--- a/src/config/io.write-config.test.ts
+++ b/src/config/io.write-config.test.ts
@@ -1,6 +1,6 @@
 import fs from "node:fs/promises";
 import path from "node:path";
-import { describe, expect, it } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 import { createConfigIO } from "./io.js";
 import { withTempHome } from "./test-helpers.js";
 
@@ -174,4 +174,66 @@ describe("config io write", () => {
       ]);
     });
   });
+
+  it("logs an overwrite audit entry when replacing an existing config file", async () => {
+    await withTempHome(async (home) => {
+      const configPath = path.join(home, ".openclaw", "openclaw.json");
+      await fs.mkdir(path.dirname(configPath), { recursive: true });
+      await fs.writeFile(
+        configPath,
+        JSON.stringify({ gateway: { port: 18789 } }, null, 2),
+        "utf-8",
+      );
+      const warn = vi.fn();
+      const io = createConfigIO({
+        env: {} as NodeJS.ProcessEnv,
+        homedir: () => home,
+        logger: {
+          warn,
+          error: vi.fn(),
+        },
+      });
+
+      const snapshot = await io.readConfigFileSnapshot();
+      expect(snapshot.valid).toBe(true);
+      const next = structuredClone(snapshot.config);
+      next.gateway = {
+        ...next.gateway,
+        auth: { mode: "token" },
+      };
+
+      await io.writeConfigFile(next);
+
+      const overwriteLog = warn.mock.calls
+        .map((call) => call[0])
+        .find((entry) => typeof entry === "string" && entry.startsWith("Config overwrite:"));
+      expect(typeof overwriteLog).toBe("string");
+      expect(overwriteLog).toContain(configPath);
+      expect(overwriteLog).toContain(`${configPath}.bak`);
+      expect(overwriteLog).toContain("sha256");
+    });
+  });
+
+  it("does not log an overwrite audit entry when creating config for the first time", async () => {
+    await withTempHome(async (home) => {
+      const warn = vi.fn();
+      const io = createConfigIO({
+        env: {} as NodeJS.ProcessEnv,
+        homedir: () => home,
+        logger: {
+          warn,
+          error: vi.fn(),
+        },
+      });
+
+      await io.writeConfigFile({
+        gateway: { mode: "local" },
+      });
+
+      const overwriteLogs = warn.mock.calls.filter(
+        (call) => typeof call[0] === "string" && call[0].startsWith("Config overwrite:"),
+      );
+      expect(overwriteLogs).toHaveLength(0);
+    });
+  });
 });