diff --git a/crates/loopal-protocol/src/projection.rs b/crates/loopal-protocol/src/projection.rs
index fffdfee..cdf723a 100644
--- a/crates/loopal-protocol/src/projection.rs
+++ b/crates/loopal-protocol/src/projection.rs
@@ -111,7 +111,11 @@ fn summarize_input(input: &serde_json::Value) -> String {
     if s.len() <= 60 {
         s
     } else {
-        format!("{}...", &s[..57])
+        let mut end = 57;
+        while end > 0 && !s.is_char_boundary(end) {
+            end -= 1;
+        }
+        format!("{}...", &s[..end])
     }
 }
 
diff --git a/crates/loopal-protocol/tests/suite/projection_edge_test.rs b/crates/loopal-protocol/tests/suite/projection_edge_test.rs
index fe51076..aa34143 100644
--- a/crates/loopal-protocol/tests/suite/projection_edge_test.rs
+++ b/crates/loopal-protocol/tests/suite/projection_edge_test.rs
@@ -1,6 +1,58 @@
 use loopal_message::{ContentBlock, Message, MessageRole};
 use loopal_protocol::projection::project_messages;
 
+#[test]
+fn summarize_input_respects_utf8_boundary() {
+    // Exact reproduction of the crash: byte 57 falls inside '建' (bytes 55..58).
+    let long_chinese = serde_json::json!({
+        "subject": "创建 content-pipeline 目录结构",
+        "description": "创建 channels/content-pipeline/drafts/ 目录和 .gitkeep",
+        "activeForm": "Creating directories"
+    });
+    let raw = long_chinese.to_string();
+    assert!(
+        raw.len() > 60,
+        "input must exceed 60 bytes to trigger truncation"
+    );
+    assert!(
+        !raw.is_char_boundary(57),
+        "byte 57 must be mid-character to test the fix"
+    );
+
+    let msg = Message {
+        id: None,
+        role: MessageRole::Assistant,
+        content: vec![ContentBlock::ToolUse {
+            id: "tu-utf8".into(),
+            name: "TaskCreate".into(),
+            input: long_chinese,
+        }],
+    };
+    let display = project_messages(&[msg]);
+    let summary = &display[0].tool_calls[0].summary;
+    assert!(summary.starts_with("TaskCreate("));
+    assert!(summary.ends_with("...)"));
+    // Verify truncated content is valid UTF-8 (iterating chars would panic otherwise)
+    assert!(summary.chars().count() > 0);
+}
+
+#[test]
+fn summarize_input_short_input_not_truncated() {
+    let short = serde_json::json!({"path": "/tmp/foo"});
+    let msg = Message {
+        id: None,
+        role: MessageRole::Assistant,
+        content: vec![ContentBlock::ToolUse {
+            id: "tu-short".into(),
+            name: "Read".into(),
+            input: short.clone(),
+        }],
+    };
+    let display = project_messages(&[msg]);
+    let summary = &display[0].tool_calls[0].summary;
+    assert_eq!(summary, &format!("Read({})", short));
+}
+
 #[test]
 fn project_multiple_images_count() {
     let msg = Message {
diff --git a/crates/tools/process/bash/src/bg_monitor.rs b/crates/tools/process/bash/src/bg_monitor.rs
index 69cad40..ae24b33 100644
--- a/crates/tools/process/bash/src/bg_monitor.rs
+++ b/crates/tools/process/bash/src/bg_monitor.rs
@@ -96,7 +96,11 @@ pub fn truncate_cmd(cmd: &str, max: usize) -> String {
     if single_line.len() <= max {
         single_line
     } else {
-        format!("{}…", &single_line[..max - 1])
+        let mut end = max.saturating_sub(1);
+        while end > 0 && !single_line.is_char_boundary(end) {
+            end -= 1;
+        }
+        format!("{}…", &single_line[..end])
     }
 }
 
@@ -112,3 +116,49 @@ pub async fn read_pipe<R: tokio::io::AsyncRead + Unpin>(buf: &Mutex<String>, rea
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn truncate_cmd_ascii_within_limit() {
+        assert_eq!(truncate_cmd("ls -la", 10), "ls -la");
+    }
+
+    #[test]
+    fn truncate_cmd_ascii_exceeds_limit() {
+        let result = truncate_cmd("echo hello world foo bar", 10);
+        assert!(result.ends_with('…'));
+        // 9 ASCII chars + 3-byte '…' = 12 bytes max
+        assert!(result.len() <= 12);
+    }
+
+    #[test]
+    fn truncate_cmd_multibyte_boundary() {
+        // '创' = 3 bytes, so "echo 创建目录" has byte offsets where max could land mid-char
+        let result = truncate_cmd("echo 创建目录结构并初始化配置文件", 12);
+        assert!(result.ends_with('…'));
+        // Strip the trailing '…' (3 bytes) and verify the prefix is valid UTF-8
+        let prefix = &result[..result.len() - '…'.len_utf8()];
+        assert!(prefix.is_char_boundary(prefix.len()));
+    }
+
+    #[test]
+    fn truncate_cmd_max_exactly_inside_char() {
+        // "创" is bytes 0..3; max=2 lands inside it, must back up to 0
+        let result = truncate_cmd("创建", 2);
+        assert_eq!(result, "…"); // backed up to 0, only ellipsis remains
+    }
+
+    #[test]
+    fn truncate_cmd_collapses_whitespace() {
+        assert_eq!(truncate_cmd("ls  -la   /tmp", 20), "ls -la /tmp");
+    }
+
+    #[test]
+    fn truncate_cmd_zero_max() {
+        let result = truncate_cmd("hello", 0);
+        assert_eq!(result, "…");
+    }
+}
diff --git a/src/bootstrap/multiprocess.rs b/src/bootstrap/multiprocess.rs
index 21b4612..441be2d 100644
--- a/src/bootstrap/multiprocess.rs
+++ b/src/bootstrap/multiprocess.rs
@@ -58,13 +58,20 @@ pub async fn run(
     // 9. Load display history or show welcome
     let session_manager = loopal_runtime::SessionManager::new()?;
     if let Some(sid) = resume {
-        if let Ok((session, messages)) = session_manager.resume_session(sid) {
-            session_ctrl.load_display_history(project_messages(&messages));
-            super::sub_agent_resume::load_sub_agent_histories(
-                &session_ctrl,
-                &session,
-                &session_manager,
-            );
+        match session_manager.resume_session(sid) {
+            Ok((session, messages)) => {
+                session_ctrl.load_display_history(project_messages(&messages));
+                super::sub_agent_resume::load_sub_agent_histories(
+                    &session_ctrl,
+                    &session,
+                    &session_manager,
+                );
+            }
+            Err(e) => {
+                tracing::warn!(session_id = sid, error = %e, "failed to resume session");
+                let short = &sid[..8.min(sid.len())];
+                session_ctrl.push_system_message(format!("Failed to resume session {short}: {e}"));
+            }
         }
     } else {
         let display_path = super::abbreviate_home(cwd);