Add configurable agent name and system prompt

config.example.toml

@@ -11,6 +11,22 @@ model = "claude-sonnet-4-20250514"
 # Maximum tokens for responses
 max_tokens = 8192
 
+# =============================================================================
+# Agent Persona
+# =============================================================================
+# Customize the agent's name and personality. These settings affect how the
+# agent introduces itself and displays its name in the chat interface.
+
+[agent]
+# Custom name for the agent (default: "Codey")
+# This appears in the chat header and welcome message.
+# name = "Jarvis"
+
+# Custom system prompt intro/personality (replaces the default "You are Codey..." paragraph)
+# Use this to give the agent a different persona or specialized behavior.
+# The capabilities and guidelines section is automatically appended.
+# system_prompt = "You are Jarvis, a sophisticated AI assistant with a dry wit and encyclopedic knowledge."
+
 [auth]
 # Authentication method: "oauth" or "api_key"
 method = "oauth"

src/app.rs

@@ -22,7 +22,7 @@ use crate::llm::{Agent, AgentId, AgentRegistry, AgentStatus, AgentStep, RequestM
 #[cfg(feature = "profiling")]
 use crate::{profile_frame, profile_span};
 use crate::notifications::{Notification, NotificationQueue};
-use crate::prompts::{SystemPrompt, COMPACTION_PROMPT, WELCOME_MESSAGE};
+use crate::prompts::{SystemPrompt, COMPACTION_PROMPT, welcome_message};
 use crate::tool_filter::ToolFilters;
 use crate::tools::{
     init_agent_context, init_browser_context, update_agent_oauth, EffectResult, ToolDecision,
@@ -276,10 +276,12 @@ impl App {
             None
         };
 
+        let agent_name = config.agent.name().to_string();
+
         Ok(Self {
             config,
             terminal,
-            chat: ChatView::new(transcript, terminal_size.0, chat_height),
+            chat: ChatView::new(transcript, terminal_size.0, chat_height, agent_name),
             input: InputBox::new(),
             should_quit: false,
             continue_session,
@@ -338,7 +340,8 @@ impl App {
         init_browser_context(&self.config.browser);
 
         // Use dynamic prompt builder so mdsh commands are re-executed on each LLM call
-        let system_prompt = SystemPrompt::new();
+        let system_prompt = SystemPrompt::with_config(&self.config);
+        let agent_name = system_prompt.agent_name().to_string();
         let mut agent = Agent::with_dynamic_prompt(
             AgentRuntimeConfig::foreground(&self.config),
             Box::new(move || system_prompt.build()),
@@ -350,7 +353,7 @@ impl App {
             agent.restore_from_transcript(&self.chat.transcript);
         } else {
             self.chat
-                .add_turn(Role::Assistant, TextBlock::pending(WELCOME_MESSAGE));
+                .add_turn(Role::Assistant, TextBlock::pending(&welcome_message(&agent_name)));
         }
         self.agents.register(agent);
 

src/config.rs

@@ -104,6 +104,7 @@ impl AgentRuntimeConfig {
 #[serde(default)]
 pub struct Config {
     pub general: GeneralConfig,
+    pub agent: AgentPersonaConfig,
     pub agents: AgentsConfig,
     pub auth: AuthConfig,
     pub ui: UiConfig,
@@ -117,6 +118,7 @@ impl Default for Config {
     fn default() -> Self {
         Self {
             general: GeneralConfig::default(),
+            agent: AgentPersonaConfig::default(),
             agents: AgentsConfig::default(),
             auth: AuthConfig::default(),
             ui: UiConfig::default(),
@@ -258,6 +260,25 @@ impl Default for GeneralConfig {
     }
 }
 
+/// Agent persona configuration (name and personality)
+#[cfg(feature = "cli")]
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+#[serde(default)]
+pub struct AgentPersonaConfig {
+    /// Custom name for the agent (defaults to "Codey")
+    pub name: Option<String>,
+    /// Custom system prompt intro/personality (replaces the default "You are Codey..." paragraph)
+    pub system_prompt: Option<String>,
+}
+
+#[cfg(feature = "cli")]
+impl AgentPersonaConfig {
+    /// Get the agent name, falling back to default
+    pub fn name(&self) -> &str {
+        self.name.as_deref().unwrap_or(crate::prompts::DEFAULT_AGENT_NAME)
+    }
+}
+
 #[cfg(feature = "cli")]
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(default)]
@@ -537,4 +558,40 @@ deny = ["\\.env$"]
         assert_eq!(config.tools.read_file.allow, vec!["\\.rs$"]);
         assert_eq!(config.tools.read_file.deny, vec!["\\.env$"]);
     }
+
+    #[test]
+    fn test_agent_persona_defaults() {
+        let config = Config::default();
+        assert!(config.agent.name.is_none());
+        assert!(config.agent.system_prompt.is_none());
+        assert_eq!(config.agent.name(), "Codey");
+    }
+
+    #[test]
+    fn test_parse_agent_persona() {
+        let toml = r#"
+[agent]
+name = "Jarvis"
+system_prompt = "You are Jarvis, Tony Stark's AI assistant."
+"#;
+        let config: Config = toml::from_str(toml).unwrap();
+        assert_eq!(config.agent.name, Some("Jarvis".to_string()));
+        assert_eq!(
+            config.agent.system_prompt,
+            Some("You are Jarvis, Tony Stark's AI assistant.".to_string())
+        );
+        assert_eq!(config.agent.name(), "Jarvis");
+    }
+
+    #[test]
+    fn test_agent_persona_name_only() {
+        let toml = r#"
+[agent]
+name = "Assistant"
+"#;
+        let config: Config = toml::from_str(toml).unwrap();
+        assert_eq!(config.agent.name, Some("Assistant".to_string()));
+        assert!(config.agent.system_prompt.is_none());
+        assert_eq!(config.agent.name(), "Assistant");
+    }
 }

src/prompts.rs

@@ -16,13 +16,35 @@ const ESH_SCRIPT: &str = include_str!("../lib/esh/esh");
 /// Filename for custom system prompt additions
 pub const SYSTEM_MD_FILENAME: &str = "SYSTEM.md";
 
-/// Welcome message shown when the application starts
+/// Default agent name
+pub const DEFAULT_AGENT_NAME: &str = "Codey";
+
+/// Generate welcome message with the given agent name
+pub fn welcome_message(name: &str) -> String {
+    format!(
+        "Welcome to {}! I'm your AI coding assistant. How can I help you today?",
+        name
+    )
+}
+
+/// Default welcome message (for backward compatibility)
 pub const WELCOME_MESSAGE: &str =
     "Welcome to Codey! I'm your AI coding assistant. How can I help you today?";
 
-/// Main system prompt for the primary agent
-pub const SYSTEM_PROMPT: &str = r#"You are Codey, an AI coding assistant running in a terminal interface.
+/// Default intro paragraph for the system prompt
+pub const DEFAULT_SYSTEM_INTRO: &str =
+    "You are Codey, an AI coding assistant running in a terminal interface.";
+
+/// Generate the default intro with a custom agent name
+pub fn default_system_intro(name: &str) -> String {
+    format!(
+        "You are {}, an AI coding assistant running in a terminal interface.",
+        name
+    )
+}
 
+/// System prompt capabilities and guidelines (appended after the intro)
+pub const SYSTEM_PROMPT_BODY: &str = r#"
 ## Capabilities
 You have access to the following tools:
 - `read_file`: Read file contents, optionally with line ranges
@@ -79,6 +101,23 @@ You will be notified with a message when background tasks finish.
 - Always get confirmation before making destructive changes (this includes building a release)
 "#;
 
+/// Build the base system prompt with optional config overrides
+pub fn build_base_system_prompt(config: Option<&Config>) -> String {
+    let intro = match config {
+        Some(cfg) => {
+            // If custom system_prompt is provided, use it directly
+            if let Some(ref custom) = cfg.agent.system_prompt {
+                custom.clone()
+            } else {
+                // Otherwise use default intro with possibly custom name
+                default_system_intro(cfg.agent.name())
+            }
+        }
+        None => DEFAULT_SYSTEM_INTRO.to_string(),
+    };
+    format!("{}{}", intro, SYSTEM_PROMPT_BODY)
+}
+
 /// Prompt used when compacting conversation context
 pub const COMPACTION_PROMPT: &str = r#"The conversation context is getting large and needs to be compacted.
 
@@ -115,7 +154,7 @@ You have read-only access to:
 /// A system prompt builder that supports dynamic content via esh templates.
 ///
 /// The prompt is composed of:
-/// 1. The base system prompt (static)
+/// 1. The base system prompt (configurable intro + capabilities/guidelines)
 /// 2. User SYSTEM.md from ~/.config/codey/ (optional, dynamic)
 /// 3. Project SYSTEM.md from .codey/ (optional, dynamic)
 ///
@@ -125,29 +164,60 @@ You have read-only access to:
 pub struct SystemPrompt {
     user_path: Option<PathBuf>,
     project_path: PathBuf,
+    /// Custom agent name (None = use default "Codey")
+    agent_name: Option<String>,
+    /// Custom system prompt intro (None = use default)
+    custom_intro: Option<String>,
 }
 
 impl SystemPrompt {
-    /// Create a new SystemPrompt with default paths.
+    /// Create a new SystemPrompt with default paths and no config overrides.
     pub fn new() -> Self {
         let user_path = Config::config_dir().map(|d| d.join(SYSTEM_MD_FILENAME));
         let project_path = Path::new(CODEY_DIR).join(SYSTEM_MD_FILENAME);
 
         Self {
             user_path,
             project_path,
+            agent_name: None,
+            custom_intro: None,
+        }
+    }
+
+    /// Create a new SystemPrompt with config-based overrides.
+    pub fn with_config(config: &Config) -> Self {
+        let user_path = Config::config_dir().map(|d| d.join(SYSTEM_MD_FILENAME));
+        let project_path = Path::new(CODEY_DIR).join(SYSTEM_MD_FILENAME);
+
+        Self {
+            user_path,
+            project_path,
+            agent_name: config.agent.name.clone(),
+            custom_intro: config.agent.system_prompt.clone(),
         }
     }
 
+    /// Get the agent name (custom or default)
+    pub fn agent_name(&self) -> &str {
+        self.agent_name.as_deref().unwrap_or(DEFAULT_AGENT_NAME)
+    }
+
     /// Build the complete system prompt.
     ///
     /// This reads and processes all SYSTEM.md files, executing any embedded
     /// shell commands via esh (`<%= command %>`). The result is the concatenation of:
-    /// - Base system prompt
+    /// - Base system prompt (with optional custom intro)
     /// - User SYSTEM.md content (if exists)
     /// - Project SYSTEM.md content (if exists)
     pub fn build(&self) -> String {
-        let mut prompt = SYSTEM_PROMPT.to_string();
+        // Build the intro portion
+        let intro = if let Some(ref custom) = self.custom_intro {
+            custom.clone()
+        } else {
+            default_system_intro(self.agent_name())
+        };
+
+        let mut prompt = format!("{}{}", intro, SYSTEM_PROMPT_BODY);
 
         // Append user SYSTEM.md if it exists
         if let Some(ref user_path) = self.user_path {

src/ui/chat.rs

@@ -50,10 +50,12 @@ pub struct ChatView {
     frozen_turn_ids: HashSet<usize>,
     /// Mapping of turn ID to line count (for frozen turns)
     turn_line_counts: HashMap<usize, usize>,
+    /// Agent name for display (configurable)
+    agent_name: String,
 }
 
 impl ChatView {
-    pub fn new(transcript: Transcript, width: u16, max_lines: usize) -> Self {
+    pub fn new(transcript: Transcript, width: u16, max_lines: usize, agent_name: String) -> Self {
         Self {
             transcript,
             width,
@@ -62,6 +64,7 @@ impl ChatView {
             committed_count: 0,
             frozen_turn_ids: HashSet::new(),
             turn_line_counts: HashMap::new(),
+            agent_name,
         }
     }
 
@@ -140,7 +143,7 @@ impl ChatView {
             if self.frozen_turn_ids.contains(&turn.id) {
                 continue;
             }
-            let render = Self::render_turn_to_lines(turn, self.width);
+            let render = Self::render_turn_to_lines(turn, self.width, &self.agent_name);
             self.turn_line_counts.insert(turn.id, render.len());
             active_lines.extend(render);
         }
@@ -214,7 +217,7 @@ impl ChatView {
     }
 
     /// Render a turn to lines (header + content + separator)
-    fn render_turn_to_lines(turn: &Turn, width: u16) -> Vec<Line<'static>> {
+    fn render_turn_to_lines(turn: &Turn, width: u16, agent_name: &str) -> Vec<Line<'static>> {
         #[cfg(feature = "profiling")]
         let _span = profile_span!("ChatView::render_turn_to_lines");
 
@@ -223,19 +226,19 @@ impl ChatView {
         // Role header
         let (role_text, role_style) = match turn.role {
             Role::User => (
-                "You",
+                "You".to_string(),
                 Style::default()
                     .fg(Color::Green)
                     .add_modifier(Modifier::BOLD),
             ),
             Role::Assistant => (
-                "Codey",
+                agent_name.to_string(),
                 Style::default()
                     .fg(Color::Cyan)
                     .add_modifier(Modifier::BOLD),
             ),
             Role::System => (
-                "System",
+                "System".to_string(),
                 Style::default()
                     .fg(Color::Yellow)
                     .add_modifier(Modifier::BOLD),