diff --git a/CHANGELOG.md b/CHANGELOG.md
index 02bd6a3d3ca..dfe9aada861 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ Docs: https://docs.openclaw.ai
 ### Fixes
 
 - Gateway/models: move local-provider pricing opt-outs, OpenRouter/LiteLLM aliases, and proxy passthrough pricing lookup into plugin manifest metadata so core no longer carries extension-specific pricing tables. Thanks @codex.
+- Agents/Claude CLI: force live-session launches to include `--output-format stream-json` whenever OpenClaw adds `--input-format stream-json`, so new Claude CLI sessions no longer fail immediately while reusable sessions keep working. Fixes #72206. Thanks @kwangwonkoh and @Xivi08.
 - CLI/plugins: accept ClawHub plugin API wildcard ranges such as `*` without rejecting compatible plugin installs, while still requiring a valid runtime API version. Fixes #56446; supersedes #56466. Thanks @darconada and @claygeo.
 - Agents/sessions: acquire the session write lock only after cold bootstrap, plugin, and tool setup so fallback runs are not blocked by stalled pre-model startup work. Thanks @codex.
 - Browser/plugins: auto-start the bundled browser plugin when root `browser` config is present, including restrictive plugin allowlists, and ignore stale persisted plugin registries whose package paths no longer exist. Thanks @codex.
diff --git a/src/agents/cli-runner.spawn.test.ts b/src/agents/cli-runner.spawn.test.ts
index d7facd9e57d..db147457fa6 100644
--- a/src/agents/cli-runner.spawn.test.ts
+++ b/src/agents/cli-runner.spawn.test.ts
@@ -786,14 +786,7 @@ describe("runCliAgent spawn path", () => {
           runId: "run-live-1",
           prompt: "first",
           backend: {
-            args: [
-              "-p",
-              "--output-format",
-              "stream-json",
-              "--strict-mcp-config",
-              "--mcp-config",
-              "/tmp/mcp-one.json",
-            ],
+            args: ["-p", "--strict-mcp-config", "--mcp-config", "/tmp/mcp-one.json"],
             liveSession: "claude-stdio",
           },
           mcpConfigHash: "same-mcp-config",
@@ -806,14 +799,7 @@ describe("runCliAgent spawn path", () => {
           runId: "run-live-2",
           prompt: "second",
           backend: {
-            args: [
-              "-p",
-              "--output-format",
-              "stream-json",
-              "--strict-mcp-config",
-              "--mcp-config",
-              "/tmp/mcp-two.json",
-            ],
+            args: ["-p", "--strict-mcp-config", "--mcp-config", "/tmp/mcp-two.json"],
             liveSession: "claude-stdio",
           },
           mcpConfigHash: "same-mcp-config",
@@ -829,6 +815,7 @@ describe("runCliAgent spawn path", () => {
       expect(supervisorSpawnMock).toHaveBeenCalledOnce();
       expect(spawnInput.stdinMode).toBe("pipe-open");
       expect(spawnInput.argv).toContain("--input-format");
+      expect(spawnInput.argv).toContain("--output-format");
       expect(spawnInput.argv).toContain("stream-json");
       expect(spawnInput.argv).toContain("--replay-user-messages");
       expect(spawnInput.argv).not.toContain("--session-id");
@@ -1214,6 +1201,36 @@ describe("runCliAgent spawn path", () => {
     expect(args).not.toContain("current prompt");
   });
 
+  it("adds Claude stream-json output format when building live session argv", () => {
+    const backend: PreparedCliRunContext["preparedBackend"]["backend"] = {
+      command: "claude",
+      args: ["-p"],
+      output: "jsonl",
+      input: "stdin",
+      sessionArg: "--session-id",
+      systemPromptArg: "--append-system-prompt",
+      systemPromptFileArg: "--append-system-prompt-file",
+    };
+
+    const args = buildClaudeLiveArgs({
+      args: ["-p"],
+      backend,
+      systemPrompt: "current prompt",
+      useResume: false,
+    });
+
+    expect(args).toEqual(
+      expect.arrayContaining([
+        "--input-format",
+        "stream-json",
+        "--output-format",
+        "stream-json",
+        "--permission-prompt-tool",
+        "stdio",
+      ]),
+    );
+  });
+
   it("restarts Claude live sessions for env changes and fresh retries", async () => {
     const cancels: Array<ReturnType<typeof vi.fn>> = [];
     const turnResults = ["first-ok", "resume-ok", "env-ok", "fresh-ok"];
diff --git a/src/agents/cli-runner/claude-live-session.ts b/src/agents/cli-runner/claude-live-session.ts
index c0975be3699..6b9fdfd0ded 100644
--- a/src/agents/cli-runner/claude-live-session.ts
+++ b/src/agents/cli-runner/claude-live-session.ts
@@ -147,8 +147,12 @@ export function buildClaudeLiveArgs(params: {
   return appendArg(
     upsertArgValue(
       upsertArgValue(
-        stripLiveProcessArgs(params.args, params.backend, params.useResume),
-        "--input-format",
+        upsertArgValue(
+          stripLiveProcessArgs(params.args, params.backend, params.useResume),
+          "--input-format",
+          "stream-json",
+        ),
+        "--output-format",
         "stream-json",
       ),
       "--permission-prompt-tool",