fix(config): preserve empty patch objects

src/cli/config-cli.test.ts

@@ -81,6 +81,15 @@ function setSnapshotOnce(snapshot: ConfigFileSnapshot) {
   mockReadConfigFileSnapshot.mockResolvedValueOnce(snapshot);
 }
 
+function writeTempJson5File(prefix: string, value: unknown): string {
+  const pathname = path.join(
+    os.tmpdir(),
+    `${prefix}-${Date.now()}-${Math.random().toString(16).slice(2)}.json5`,
+  );
+  fs.writeFileSync(pathname, JSON.stringify(value), "utf8");
+  return pathname;
+}
+
 function withRuntimeDefaults(resolved: OpenClawConfig): OpenClawConfig {
   return {
     ...resolved,
@@ -733,7 +742,10 @@ describe("config cli", () => {
       const configCommand = program.commands.find((command) => command.name() === "config");
       const setCommand = configCommand?.commands.find((command) => command.name() === "set");
       const helpText = setCommand?.helpInformation() ?? "";
+      const configHelpText = configCommand?.helpInformation() ?? "";
 
+      expect(configHelpText).toContain("get/set/patch/unset/file/schema/validate");
+      expect(configHelpText).not.toContain("get/set/apply/unset/file/schema/validate");
       expect(helpText).toContain("--strict-json");
       expect(helpText).toContain("--json");
       expect(helpText).toContain("Legacy alias for --strict-json");
@@ -1462,6 +1474,71 @@ describe("config cli", () => {
       ).toEqual({ source: "env", provider: "default", id: "DISCORD_BOT_TOKEN" });
     });
 
+    it("preserves empty object values in config patch", async () => {
+      const resolved = {
+        agents: {
+          defaults: {
+            models: {
+              "openai/gpt-5.4": { alias: "GPT 5.4" },
+            },
+          },
+        },
+      } as unknown as OpenClawConfig;
+      setSnapshot(resolved, resolved);
+
+      const pathname = writeTempJson5File("openclaw-config-patch-empty-object", {
+        agents: {
+          defaults: {
+            models: {
+              "openai/gpt-5.5": {},
+            },
+          },
+        },
+      });
+      try {
+        await runConfigCommand(["config", "patch", "--file", pathname]);
+      } finally {
+        fs.rmSync(pathname, { force: true });
+      }
+
+      const written = mockWriteConfigFile.mock.calls[0]?.[0] as Record<string, unknown>;
+      expect(
+        ((written.agents as Record<string, unknown>).defaults as Record<string, unknown>).models,
+      ).toEqual({
+        "openai/gpt-5.4": { alias: "GPT 5.4" },
+        "openai/gpt-5.5": {},
+      });
+    });
+
+    it("treats empty object config patches as recursive merges", async () => {
+      const resolved = {
+        channels: {
+          slack: {
+            enabled: true,
+            mode: "socket",
+          },
+        },
+      } as unknown as OpenClawConfig;
+      setSnapshot(resolved, resolved);
+
+      const pathname = writeTempJson5File("openclaw-config-patch-empty-merge", {
+        channels: {
+          slack: {},
+        },
+      });
+      try {
+        await runConfigCommand(["config", "patch", "--file", pathname]);
+      } finally {
+        fs.rmSync(pathname, { force: true });
+      }
+
+      const written = mockWriteConfigFile.mock.calls[0]?.[0] as Record<string, unknown>;
+      expect((written.channels as Record<string, unknown>).slack).toEqual({
+        enabled: true,
+        mode: "socket",
+      });
+    });
+
     it("dry-runs config patch and resolves changed SecretRefs", async () => {
       const resolved = {
         secrets: {

src/cli/config-cli.ts

@@ -915,7 +915,7 @@ function configPatchModeError(message: string): Error {
 }
 
 async function readStdinText(): Promise<string> {
-  let raw = "";
+  const chunks: string[] = [];
   let bytes = 0;
   if (process.stdin.isTTY) {
     throw configPatchModeError(
@@ -931,9 +931,9 @@ async function readStdinText(): Promise<string> {
         `--stdin input exceeds ${CONFIG_PATCH_STDIN_MAX_BYTES} bytes; use --file <path> for larger patches.`,
       );
     }
-    raw += text;
+    chunks.push(text);
   }
-  return raw;
+  return chunks.join("");
 }
 
 async function readConfigPatchInput(opts: ConfigPatchOptions): Promise<unknown> {
@@ -972,7 +972,7 @@ function buildDeleteOperation(path: PathSegment[]): ConfigSetOperation {
 function buildApplyValueOperation(params: {
   path: PathSegment[];
   value: unknown;
-  mutation?: "set" | "replace";
+  mutation?: ConfigSetOperation["mutation"];
 }): ConfigSetOperation {
   const ref = isPlainRecord(params.value) ? coerceSecretRef(params.value) : null;
   if (ref) {
@@ -1026,6 +1026,10 @@ function buildConfigPatchOperations(params: {
       return;
     }
     if (isPlainRecord(value)) {
+      if (path.length > 0 && Object.keys(value).length === 0) {
+        operations.push(buildApplyValueOperation({ path, value, mutation: "merge" }));
+        return;
+      }
       for (const [key, child] of Object.entries(value)) {
         visit(child, [...path, key]);
       }
@@ -1373,7 +1377,7 @@ async function runConfigOperations(params: {
   runtime: RuntimeEnv;
   operations: ConfigSetOperation[];
   options: ConfigMutationOptions;
-  successMode: "set" | "apply";
+  successMode: "set" | "patch";
 }) {
   const { runtime, operations, options } = params;
   if (
@@ -1640,7 +1644,7 @@ export async function runConfigPatch(opts: {
         allowExec: opts.cliOptions.allowExec,
         json: opts.cliOptions.json,
       },
-      successMode: "apply",
+      successMode: "patch",
     });
   } catch (err) {
     handleConfigMutationError({ err, runtime, options: opts.cliOptions });
@@ -1795,7 +1799,7 @@ export function registerConfigCli(program: Command) {
   const cmd = program
     .command("config")
     .description(
-      "Non-interactive config helpers (get/set/apply/unset/file/schema/validate). Run without subcommand for guided setup.",
+      "Non-interactive config helpers (get/set/patch/unset/file/schema/validate). Run without subcommand for guided setup.",
     )
     .addHelpText(
       "after",