fix: prevent UTF-8 multibyte character boundary panic on string truncation

Fixes: A3S-Lab#23

- core/agent.rs: truncate_utf8() instead of byte slice for compact summary
- core/text.rs: add Chinese/multibyte regression tests for truncate_utf8
- sdk/python: fix __repr__ truncation in progress, idle, task_types, lib.rs
- Bump version to 1.8.4

Author: claude

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "a3s-code-core"
-version = "1.8.3"
+version = "1.8.4"
 edition = "2021"
 authors = ["A3S Lab Team"]
 license = "MIT"

core/Cargo.toml

@@ -22,6 +22,7 @@ use crate::planning::{AgentGoal, ExecutionPlan, TaskStatus};
 use crate::prompts::{AgentStyle, DetectionConfidence, PlanningMode, SystemPromptSlots};
 use crate::queue::SessionCommand;
 use crate::session_lane_queue::SessionLaneQueue;
+use crate::text::truncate_utf8;
 use crate::tool_search::ToolIndex;
 use crate::tools::{ToolContext, ToolExecutor, ToolStreamEvent};
 use anyhow::{Context, Result};
@@ -722,7 +723,7 @@ impl AgentLoop {
         };
         let compact = raw.split_whitespace().collect::<Vec<_>>().join(" ");
         if compact.len() > 180 {
-            format!("{}...", &compact[..180])
+            format!("{}...", truncate_utf8(&compact, 180))
         } else {
             compact
         }

core/src/agent.rs

@@ -27,4 +27,35 @@ mod tests {
         assert_eq!(truncated, "执");
         assert!(truncated.is_char_boundary(truncated.len()));
     }
+
+    #[test]
+    fn truncate_utf8_issue_23_real_payload() {
+        // Exact scenario from GitHub issue #23: byte 180 falls inside '费' (bytes 178..181)
+        let raw = "# Issue Summary\n\n# Issue Source\n- issue_id: 297936\n- org_id: 848\n- create_time: 2025-10-29 03:16:16\n- item_id: 11089\n\n## issue_name\n用户请求处理视频分析任务，涉及计费(费用:100元)\n";
+        let compact = raw.split_whitespace().collect::<Vec<_>>().join(" ");
+        // After joining with spaces, byte 180 splits a Chinese char
+        assert!(
+            !compact.is_char_boundary(180),
+            "compact len={}",
+            compact.len()
+        );
+        // The original code did: &compact[..180] — this panicked
+        let truncated = truncate_utf8(&compact, 180);
+        assert!(truncated.is_char_boundary(truncated.len()));
+    }
+
+    #[test]
+    fn truncate_utf8_chinese_only() {
+        let s = "用户请求处理视频分析任务，涉及计费";
+        let truncated = truncate_utf8(s, 15);
+        assert!(truncated.is_char_boundary(truncated.len()));
+        // Should not split: 费 is 3 bytes (bytes 12-14), so 15 should stop before it
+    }
+
+    #[test]
+    fn truncate_utf8_mixed_ascii_chinese() {
+        let s = "hello你好world世界test";
+        let truncated = truncate_utf8(s, 10);
+        assert!(truncated.is_char_boundary(truncated.len()));
+    }
 }

core/src/text.rs

@@ -1,6 +1,6 @@
 {
   "name": "@a3s-lab/code",
-  "version": "1.8.3",
+  "version": "1.8.4",
   "description": "A3S Code - Native AI coding agent library for Node.js",
   "main": "index.js",
   "types": "index.d.ts",
@@ -44,11 +44,11 @@
     "test:loop": "tsx --tsconfig examples/tsconfig.json examples/test_loop_commands.ts"
   },
   "optionalDependencies": {
-    "@a3s-lab/code-darwin-arm64": "1.8.3",
-    "@a3s-lab/code-linux-x64-gnu": "1.8.3",
-    "@a3s-lab/code-linux-x64-musl": "1.8.3",
-    "@a3s-lab/code-linux-arm64-gnu": "1.8.3",
-    "@a3s-lab/code-linux-arm64-musl": "1.8.3",
-    "@a3s-lab/code-win32-x64-msvc": "1.8.3"
+    "@a3s-lab/code-darwin-arm64": "1.8.4",
+    "@a3s-lab/code-linux-x64-gnu": "1.8.4",
+    "@a3s-lab/code-linux-x64-musl": "1.8.4",
+    "@a3s-lab/code-linux-arm64-gnu": "1.8.4",
+    "@a3s-lab/code-linux-arm64-musl": "1.8.4",
+    "@a3s-lab/code-win32-x64-msvc": "1.8.4"
   }
 }

sdk/node/package.json

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "a3s-code"
-version = "1.8.3"
+version = "1.8.4"
 description = "A3S Code Python bootstrap package that fetches platform-native binaries from GitHub Releases"
 readme = "../python/README.md"
 license = { text = "MIT" }

sdk/python-bootstrap/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "maturin"
 
 [project]
 name = "a3s-code"
-version = "1.8.3"
+version = "1.8.4"
 description = "A3S Code - Native Python bindings for the AI coding agent"
 readme = "README.md"
 license = {text = "MIT"}

sdk/python/pyproject.toml

@@ -9,6 +9,8 @@ use a3s_code_core::task::idle::{
 };
 use pyo3::prelude::*;
 
+use crate::truncate_utf8;
+
 // ============================================================================
 // IdlePhase
 // ============================================================================
@@ -110,7 +112,7 @@ impl PyIdleTurn {
         format!(
             "IdleTurn(text={:?}, tool_calls={}, files={})",
             if self.text.len() > 30 {
-                format!("{}...", &self.text[..30])
+                format!("{}...", truncate_utf8(&self.text, 30))
             } else {
                 self.text.clone()
             },
@@ -204,7 +206,7 @@ impl PyEpisodicEntry {
         format!(
             "EpisodicEntry(description={:?}, importance={})",
             if self.description.len() > 40 {
-                format!("{}...", &self.description[..40])
+                format!("{}...", truncate_utf8(&self.description, 40))
             } else {
                 self.description.clone()
             },
@@ -258,7 +260,7 @@ impl PyIdleTask {
             self.id,
             self.phase.phase,
             if self.reason.len() > 30 {
-                format!("{}...", &self.reason[..30])
+                format!("{}...", truncate_utf8(&self.reason, 30))
             } else {
                 self.reason.clone()
             }

sdk/python/src/idle.rs

@@ -68,6 +68,24 @@ use std::sync::{
 use tokio::runtime::Runtime;
 use tokio::sync::Mutex;
 
+// ============================================================================
+// Utilities
+// ============================================================================
+
+/// Truncate a UTF-8 string to at most `max_bytes` bytes, without splitting
+/// a multibyte character. Falls back to the full string if it's already
+/// within the limit.
+fn truncate_utf8(s: &str, max_bytes: usize) -> &str {
+    if s.len() <= max_bytes {
+        return s;
+    }
+    let mut end = max_bytes;
+    while end > 0 && !s.is_char_boundary(end) {
+        end -= 1;
+    }
+    &s[..end]
+}
+
 // ============================================================================
 // Task Module Bindings
 // ============================================================================
@@ -149,7 +167,7 @@ impl PyAgentResult {
         format!(
             "AgentResult(text={:?}, tool_calls={}, tokens={})",
             if self.text.len() > 80 {
-                format!("{}...", &self.text[..80])
+                format!("{}...", truncate_utf8(&self.text, 80))
             } else {
                 self.text.clone()
             },
@@ -204,7 +222,7 @@ impl PyBtwResult {
             "BtwResult(question={:?}, answer={:?}, tokens={})",
             self.question,
             if self.answer.len() > 60 {
-                format!("{}...", &self.answer[..60])
+                format!("{}...", truncate_utf8(&self.answer, 60))
             } else {
                 self.answer.clone()
             },
@@ -4224,7 +4242,7 @@ impl PySkillInfo {
             self.name,
             self.kind,
             if self.description.len() > 60 {
-                format!("{}...", &self.description[..60])
+                format!("{}...", truncate_utf8(&self.description, 60))
             } else {
                 self.description.clone()
             }
@@ -4324,7 +4342,7 @@ impl PyTeamTask {
             self.id,
             self.status,
             if self.description.len() > 60 {
-                format!("{}...", &self.description[..60])
+                format!("{}...", truncate_utf8(&self.description, 60))
             } else {
                 self.description.clone()
             }

sdk/python/src/lib.rs

@@ -9,6 +9,8 @@ use a3s_code_core::task::progress::{
 use pyo3::prelude::*;
 use std::collections::HashMap;
 
+use crate::truncate_utf8;
+
 // ============================================================================
 // TaskTokenUsage
 // ============================================================================
@@ -99,7 +101,7 @@ impl PyToolActivity {
             self.tool_name,
             self.success,
             if self.args_summary.len() > 40 {
-                format!("{}...", &self.args_summary[..40])
+                format!("{}...", truncate_utf8(&self.args_summary, 40))
             } else {
                 self.args_summary.clone()
             }