diff --git a/resources/rules.json b/resources/rules.json
index daa9e82..c2e9905 100644
--- a/resources/rules.json
+++ b/resources/rules.json
@@ -1,7 +1,14 @@
 {
   "version": "1.0",
+  "demo_only_domains": ["baidu.com", "www.baidu.com"],
   "domains": {
-    "allowed": ["oa.example.com", "erp.example.com", "hr.example.com"]
+    "allowed": [
+      "oa.example.com",
+      "erp.example.com",
+      "hr.example.com",
+      "baidu.com",
+      "www.baidu.com"
+    ]
   },
   "pipe_actions": {
     "allowed": ["click", "type", "navigate", "getText"],
diff --git a/src/pipe/browser_tool.rs b/src/pipe/browser_tool.rs
index ffaaa05..b2464be 100644
--- a/src/pipe/browser_tool.rs
+++ b/src/pipe/browser_tool.rs
@@ -97,6 +97,11 @@ impl<T: Transport> BrowserPipeTool<T> {
                         "received duplicate init after handshake".to_string(),
                     ));
                 }
+                BrowserMessage::SubmitTask { .. } => {
+                    return Err(PipeError::UnexpectedMessage(
+                        "received submit_task while waiting for response".to_string(),
+                    ));
+                }
             }
         }
     }
diff --git a/src/pipe/protocol.rs b/src/pipe/protocol.rs
index 8493ba5..f78423e 100644
--- a/src/pipe/protocol.rs
+++ b/src/pipe/protocol.rs
@@ -12,6 +12,9 @@ pub enum BrowserMessage {
         #[serde(default)]
         capabilities: Vec<String>,
     },
+    SubmitTask {
+        instruction: String,
+    },
     Response {
         seq: u64,
         success: bool,
@@ -31,6 +34,14 @@ pub enum AgentMessage {
         agent_id: String,
         supported_actions: Vec<Action>,
     },
+    LogEntry {
+        level: String,
+        message: String,
+    },
+    TaskComplete {
+        success: bool,
+        summary: String,
+    },
     Command {
         seq: u64,
         action: Action,
diff --git a/src/security/hmac.rs b/src/security/hmac.rs
index 26b1542..e11e353 100644
--- a/src/security/hmac.rs
+++ b/src/security/hmac.rs
@@ -1,6 +1,7 @@
 use hmac::{Hmac, Mac};
 use serde_json::Value;
 use sha2::{Digest, Sha256};
+use std::fmt::Write as _;
 
 use crate::pipe::Action;
 use crate::security::SecurityError;
@@ -36,13 +37,53 @@ pub fn sign_command(
 
     let mut mac = HmacSha256::new_from_slice(session_key)
         .map_err(|err| SecurityError::Hmac(err.to_string()))?;
-    mac.update(seq.to_string().as_bytes());
-    mac.update(b"|");
-    mac.update(action.as_str().as_bytes());
-    mac.update(b"|");
-    mac.update(expected_domain.as_bytes());
-    mac.update(b"|");
-    mac.update(serde_json::to_string(params)?.as_bytes());
+    let canonical = format!(
+        "{}\n{}\n{}\n{}",
+        seq,
+        action.as_str(),
+        stable_json_string(params)?,
+        expected_domain
+    );
+    mac.update(canonical.as_bytes());
 
     Ok(hex::encode(mac.finalize().into_bytes()))
 }
+
+fn stable_json_string(value: &Value) -> Result<String, SecurityError> {
+    match value {
+        Value::Null | Value::Bool(_) | Value::Number(_) | Value::String(_) => {
+            serde_json::to_string(value).map_err(SecurityError::from)
+        }
+        Value::Array(items) => {
+            let mut out = String::from("[");
+            for (index, item) in items.iter().enumerate() {
+                if index > 0 {
+                    out.push(',');
+                }
+                out.push_str(&stable_json_string(item)?);
+            }
+            out.push(']');
+            Ok(out)
+        }
+        Value::Object(map) => {
+            let mut keys: Vec<&str> = map.keys().map(String::as_str).collect();
+            keys.sort_unstable();
+
+            let mut out = String::from("{");
+            for (index, key) in keys.iter().enumerate() {
+                if index > 0 {
+                    out.push(',');
+                }
+                write!(
+                    out,
+                    "{}:{}",
+                    serde_json::to_string(key)?,
+                    stable_json_string(&map[*key])?
+                )
+                .map_err(|err| SecurityError::Hmac(err.to_string()))?;
+            }
+            out.push('}');
+            Ok(out)
+        }
+    }
+}
diff --git a/tests/task_protocol_test.rs b/tests/task_protocol_test.rs
new file mode 100644
index 0000000..14ffba5
--- /dev/null
+++ b/tests/task_protocol_test.rs
@@ -0,0 +1,96 @@
+use hmac::{Hmac, Mac};
+use serde_json::json;
+use sgclaw::pipe::{Action, AgentMessage, BrowserMessage};
+use sgclaw::security::sign_command;
+use sha2::Sha256;
+
+type HmacSha256 = Hmac<Sha256>;
+
+#[test]
+fn browser_submit_task_round_trip_uses_task_wire_format() {
+    let raw = r#"{"type":"submit_task","instruction":"打开百度并搜索今日汇率"}"#;
+    let message: BrowserMessage = serde_json::from_str(raw).unwrap();
+
+    assert_eq!(
+        message,
+        BrowserMessage::SubmitTask {
+            instruction: "打开百度并搜索今日汇率".to_string(),
+        }
+    );
+    assert_eq!(serde_json::to_string(&message).unwrap(), raw);
+}
+
+#[test]
+fn agent_task_complete_and_log_entry_serialize_with_expected_tags() {
+    let complete_raw = serde_json::to_string(&AgentMessage::TaskComplete {
+        success: true,
+        summary: "任务执行完成".to_string(),
+    })
+    .unwrap();
+    let log_raw = serde_json::to_string(&AgentMessage::LogEntry {
+        level: "info".to_string(),
+        message: "click #submit".to_string(),
+    })
+    .unwrap();
+
+    assert_eq!(
+        complete_raw,
+        r#"{"type":"task_complete","success":true,"summary":"任务执行完成"}"#
+    );
+    assert_eq!(
+        log_raw,
+        r#"{"type":"log_entry","level":"info","message":"click #submit"}"#
+    );
+}
+
+#[test]
+fn sign_command_uses_newline_canonical_string_with_stable_json() {
+    let session_key = vec![1, 2, 3, 4, 5, 6, 7, 8];
+    let params = json!({
+        "z": 9,
+        "a": { "b": 2, "a": 1 }
+    });
+    let canonical = r#"42
+click
+{"a":{"a":1,"b":2},"z":9}
+oa.example.com"#;
+
+    let mut mac = HmacSha256::new_from_slice(&session_key).unwrap();
+    mac.update(canonical.as_bytes());
+    let expected = hex::encode(mac.finalize().into_bytes());
+
+    let actual = sign_command(&session_key, 42, &Action::Click, &params, "oa.example.com").unwrap();
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn sign_command_is_order_independent_for_object_params() {
+    let session_key = vec![8, 7, 6, 5, 4, 3, 2, 1];
+    let params_a = json!({
+        "z": 9,
+        "a": { "b": 2, "a": 1 }
+    });
+    let params_b = json!({
+        "a": { "a": 1, "b": 2 },
+        "z": 9
+    });
+
+    let sig_a = sign_command(
+        &session_key,
+        7,
+        &Action::Navigate,
+        &params_a,
+        "oa.example.com",
+    )
+    .unwrap();
+    let sig_b = sign_command(
+        &session_key,
+        7,
+        &Action::Navigate,
+        &params_b,
+        "oa.example.com",
+    )
+    .unwrap();
+
+    assert_eq!(sig_a, sig_b);
+}