Add fancy ASCII art header for agent mode

The agent mode header now shows:
- Agent name in uppercase with box art
- Working directory (truncated if too long)
- Status indicators for README, AGENTS.md, and Memory loading
- Task preview if provided

Also exports truncate_for_display and adds truncate_path_for_display
helper functions in project_files module.

crates/g3-cli/src/lib.rs

@@ -28,7 +28,7 @@ use tracing::{debug, error};
 use g3_core::error_handling::{classify_error, ErrorType, RecoverableError};
 use machine_ui_writer::MachineUiWriter;
 use metrics::{format_elapsed_time, generate_turn_histogram, TurnMetrics};
-use project_files::{extract_readme_heading, read_agents_config, read_project_memory, read_project_readme};
+use project_files::{extract_readme_heading, read_agents_config, read_project_memory, read_project_readme, truncate_for_display, truncate_path_for_display};
 use simple_output::SimpleOutput;
 use ui_writer_impl::ConsoleUiWriter;
 
@@ -539,9 +539,6 @@ async fn run_agent_mode(
         ))?
     };
     
-    output.print(&format!("🤖 Running as agent: {}", agent_name));
-    output.print(&format!("📁 Working directory: {:?}", workspace_dir));
-    
     // Load config
     let mut config = g3_config::Config::load(config_path)?;
     
@@ -562,20 +559,23 @@ async fn run_agent_mode(
     let system_prompt = get_agent_system_prompt(&agent_prompt, true);
     
     // Load AGENTS.md, README, and memory - same as normal mode
-    let agents_content = read_agents_config(&workspace_dir);
-    let readme_content = read_project_readme(&workspace_dir);
-    let memory_content = read_project_memory(&workspace_dir);
+    let agents_content_opt = read_agents_config(&workspace_dir);
+    let readme_content_opt = read_project_readme(&workspace_dir);
+    let memory_content_opt = read_project_memory(&workspace_dir);
+    let has_agents = agents_content_opt.is_some();
+    let has_readme = readme_content_opt.is_some();
+    let has_memory = memory_content_opt.is_some();
     
     // Combine all content for the agent's context
     let combined_content = {
         let mut parts = Vec::new();
-        if let Some(agents) = agents_content {
+        if let Some(agents) = agents_content_opt {
             parts.push(agents);
         }
-        if let Some(readme) = readme_content {
+        if let Some(readme) = readme_content_opt {
             parts.push(readme);
         }
-        if let Some(memory) = memory_content {
+        if let Some(memory) = memory_content_opt {
             parts.push(memory);
         }
         if parts.is_empty() {
@@ -585,6 +585,31 @@ async fn run_agent_mode(
         }
     };
     
+    // Print fancy agent header
+    let agent_upper = agent_name.to_uppercase();
+    output.print("");
+    output.print("┌─────────────────────────────────────────────────────────┐");
+    output.print(&format!("│  🤖 AGENT: {:<46} │", agent_upper));
+    output.print("├─────────────────────────────────────────────────────────┤");
+    output.print(&format!("│  📁 {:<53} │", 
+        truncate_path_for_display(&workspace_dir, 53)));
+    output.print("├─────────────────────────────────────────────────────────┤");
+    
+    // Show what was loaded
+    let readme_status = if has_readme { "✓" } else { "·" };
+    let agents_status = if has_agents { "✓" } else { "·" };
+    let memory_status = if has_memory { "✓" } else { "·" };
+    output.print(&format!("│  {} README    {} AGENTS.md    {} Memory                  │",
+        readme_status, agents_status, memory_status));
+    output.print("└─────────────────────────────────────────────────────────┘");
+    output.print("");
+    
+    // Show task if provided
+    if let Some(ref task) = task {
+        output.print(&format!("📋 Task: {}", truncate_for_display(task, 60)));
+        output.print("");
+    }
+    
     // Create agent with custom system prompt
     let ui_writer = ConsoleUiWriter::new();
     // Set agent mode on UI writer for visual differentiation (light gray tool names)

crates/g3-cli/src/project_files.rs

@@ -140,7 +140,8 @@ fn find_fallback_title(content: &str) -> Option<String> {
 }
 
 /// Truncate a string for display, adding ellipsis if needed.
-fn truncate_for_display(s: &str, max_len: usize) -> String {
+/// Used for displaying long strings in fixed-width UI elements.
+pub fn truncate_for_display(s: &str, max_len: usize) -> String {
     if s.len() > max_len {
         format!("{}...", &s[..max_len - 3])
     } else {
@@ -148,6 +149,20 @@ fn truncate_for_display(s: &str, max_len: usize) -> String {
     }
 }
 
+/// Truncate a path for display, showing the end portion if too long.
+/// For paths, we want to show the most relevant part (the end).
+pub fn truncate_path_for_display(path: &std::path::Path, max_len: usize) -> String {
+    let path_str = path.display().to_string();
+    if path_str.len() > max_len {
+        // Show the end of the path with ... prefix
+        let start = path_str.len() - (max_len - 3);
+        // Find a path separator to break at cleanly if possible
+        format!("...{}", &path_str[start..])
+    } else {
+        path_str
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;