feat: enhance memory section guide and improve search tool descriptions for clarity

src/agent/system_prompt.rs

@@ -300,7 +300,7 @@ impl PromptSection for RuntimeSection {
     }
 }
 
-/// Injects relevant knowledge memories into the system prompt.
+/// Injects memory system guide and relevant knowledge memories into the system prompt.
 pub struct MemorySection;
 
 impl PromptSection for MemorySection {
@@ -309,11 +309,28 @@ impl PromptSection for MemorySection {
     }
 
     fn build(&self, ctx: &PromptContext<'_>) -> String {
+        let guide = r#"## 记忆系统
+
+### 记忆类别
+- **Knowledge（知识）**：长期存储的事实、偏好、模式、洞察。会被注入到每轮系统提示词中。
+- **Timeline（时间线）**：历史会话摘要，可通过 timeline_recall 工具主动召回。
+
+### 记忆工具
+- **memory_recall**：搜索知识记忆。参数 query 是关键词列表（空格分隔），返回相关事实、偏好、洞察。
+- **timeline_recall**：搜索历史会话摘要。可选 session_id 参数限定特定会话。
+
+### 主动记忆
+遇到以下情况时应主动使用 `memory_store` 记忆：
+- 用户明确表达的偏好（如编程语言、工具选择）
+- 重要的项目事实（如使用的框架、架构决策）
+- 值得记录的经验和教训
+"#;
+
         match ctx.memory_context {
             Some(context) if !context.is_empty() => {
-                format!("## 记忆上下文\n\n{}", context)
+                format!("{}\n\n### 记忆上下文\n\n{}", guide, context)
             }
-            _ => String::new(),
+            _ => guide.to_string(),
         }
     }
 }

src/tools/content_search.rs

@@ -59,7 +59,7 @@ impl Tool for ContentSearchTool {
     }
 
     fn description(&self) -> &str {
-        "Search file contents by regex or text pattern. Uses ripgrep (rg) if available, falls back to grep, then pure Rust."
+        "Search file contents by regex or text pattern. Internally uses ripgrep (rg) for fast searching — if rg is not available, falls back to grep, then pure Rust. Supports context lines, file filtering, and case-sensitivity options."
     }
 
     fn parameters_schema(&self) -> serde_json::Value {

src/tools/file_search.rs

@@ -56,7 +56,7 @@ impl Tool for FileSearchTool {
     }
 
     fn description(&self) -> &str {
-        "Search for files by glob pattern (e.g. '*.rs', 'test_*.rs'). Uses fd if available, falls back to find, then pure Rust."
+        "Search for files by glob pattern (e.g. '*.rs', 'test_*.rs'). Internally uses fd (fast find) for efficient searching — if fd is not available, falls back to the find command, then pure Rust glob matching."
     }
 
     fn parameters_schema(&self) -> serde_json::Value {
@@ -130,11 +130,19 @@ impl FileSearchTool {
         case_sensitive: bool,
         max_results: usize,
     ) -> anyhow::Result<Vec<String>> {
-        if which::which("fd").is_ok() {
-            match self.search_with_fd(pattern, dir, case_sensitive, max_results).await {
+        let fd_cmd = if which::which("fd").is_ok() {
+            "fd"
+        } else if which::which("fdfind").is_ok() {
+            "fdfind"
+        } else {
+            ""
+        };
+
+        if !fd_cmd.is_empty() {
+            match self.search_with_fd(pattern, dir, case_sensitive, max_results, fd_cmd).await {
                 Ok(lines) if !lines.is_empty() => return Ok(lines),
                 Ok(_) => {},
-                Err(e) => tracing::warn!("fd failed: {}, falling back", e),
+                Err(e) => tracing::warn!("{} failed: {}, falling back", fd_cmd, e),
             }
         }
 
@@ -156,8 +164,9 @@ impl FileSearchTool {
         dir: &str,
         case_sensitive: bool,
         max_results: usize,
+        fd_cmd: &str,
     ) -> anyhow::Result<Vec<String>> {
-        let mut cmd = Command::new("fd");
+        let mut cmd = Command::new(fd_cmd);
         cmd.arg("--search-path").arg(dir)
             .arg("--glob").arg(pattern)
             .arg("--color").arg("never")