feat(tui): update system message for clarity and conciseness in tool usage instructions

apps/interfaces/tui/src/action.rs

@@ -163,6 +163,14 @@ pub fn apply_action(state: &mut crate::state::AppStateRest, action: Action) {
                             rt.messages = msgs;
                         }
                     }
+                    zesdex_infrastructure::TurnEvent::TodoUpdate(content) => {
+                        state.misc.todo_content = content;
+                        state.toast_success("TODO list updated.");
+                    }
+                    zesdex_infrastructure::TurnEvent::PlanUpdate(content) => {
+                        state.misc.plan_content = content;
+                        state.toast_success("Project plan updated.");
+                    }
                     zesdex_infrastructure::TurnEvent::Done => {
                         state.turn_in_flight_flag.store(false, std::sync::atomic::Ordering::SeqCst);
                         // Mark dirty so spinner disappears

apps/interfaces/tui/src/controller/command.rs

@@ -30,6 +30,8 @@ pub enum Command {
     Compact,
     /// `/todo` — open the todo-list overlay.
     TodoOpen,
+    /// `/plan` — open the project plan overlay.
+    PlanOpen,
     /// `/usage` — open the usage-stats overlay.
     UsageOpen,
     /// Catch-all: unrecognised or non-slash input.
@@ -82,6 +84,7 @@ pub fn parse_command(text: &str) -> Command {
         "/model" => Command::ModelList,
         "/compact" => Command::Compact,
         "/todo" => Command::TodoOpen,
+        "/plan" => Command::PlanOpen,
         "/usage" => Command::UsageOpen,
         _ => Command::Unknown(cmd.to_string()),
     };
@@ -129,6 +132,9 @@ pub fn apply_command(cmd: Command) -> Vec<crate::action::Action> {
         Command::TodoOpen => {
             vec![crate::action::Action::OpenOverlay(crate::state::Overlay::Todo)]
         }
+        Command::PlanOpen => {
+            vec![crate::action::Action::OpenOverlay(crate::state::Overlay::Plan)]
+        }
         Command::UsageOpen => {
             vec![crate::action::Action::OpenOverlay(crate::state::Overlay::Usage)]
         }

apps/interfaces/tui/src/state.rs

@@ -422,6 +422,8 @@ pub enum Overlay {
     Mcp,
     /// Task list overlay.
     Todo,
+    /// Project plan overlay.
+    Plan,
     /// Session rewind / history scrubber.
     Rewind,
     /// Learning / lesson management panel.
@@ -450,6 +452,7 @@ impl Overlay {
             Overlay::Effort => "effort",
             Overlay::Mcp => "mcp",
             Overlay::Todo => "todo",
+            Overlay::Plan => "plan",
             Overlay::Rewind => "rewind",
             Overlay::Learning => "learning",
             Overlay::Usage => "usage",
@@ -498,6 +501,8 @@ pub struct MiscState {
     pub tick_count: u64,
     /// Cached content of the TODO file.
     pub todo_content: String,
+    /// Cached content of the PLAN file.
+    pub plan_content: String,
     /// Whether a lesson background task is currently running.
     pub lesson_running: bool,
     /// Text waiting to be written to the system clipboard.
@@ -518,6 +523,7 @@ impl MiscState {
             api_connected: false,
             tick_count: 0,
             todo_content: String::new(),
+            plan_content: String::new(),
             lesson_running: false,
             pending_clipboard_copy: None,
         }

apps/interfaces/tui/src/turn.rs

@@ -101,24 +101,14 @@ fn run_turn(
     let tools = all_tools();
     let defs = tool_defs(&tools);
 
-    // Build tool description list for the system prompt
-    let tool_desc: Vec<String> = tools.iter().map(|t| {
-        let params = t.parameters();
-        let required = params.get("required").and_then(|r| r.as_array())
-            .map(|a| a.iter().filter_map(|v| v.as_str()).collect::<Vec<_>>().join(", "))
-            .unwrap_or_default();
-        format!("- {}: {} (required params: {})", t.name(), t.description(), required)
-    }).collect();
-    let tool_desc_text = tool_desc.join("\n");
-
-    // Prepend system message with tool descriptions
-    let sys_msg = ChatMessage::system(format!(
-        "You are Zesdex, an AI coding agent with access to the following tools:\n\n{}\n\n\
-         When using tools, always provide ALL required parameters in your tool call. \
-         If a tool returns an error, fix the issue before retrying. \
-         Respond conversationally and helpfully.",
-        tool_desc_text
-    ));
+    // Prepend system message
+    let sys_msg = ChatMessage::system(
+        "You are Zesdex, an AI coding assistant. You have access to various tools via native function calling to help the user. \
+         For any non-trivial tasks, you MUST prioritize creating a structured plan (using `plan_enter`) and a list of TODOs (using `todowrite`) BEFORE executing any other tools or modifying files. \
+         Use other tools when necessary. If a tool returns an error, fix the issue before retrying. \
+         Respond conversationally, concisely, and helpfully."
+            .to_string(),
+    );
     messages.insert(0, sys_msg);
 
     let tool_ctx = ToolCtx::builder()

apps/interfaces/tui/src/view/overlays/mod.rs

@@ -16,6 +16,7 @@ pub mod quit_confirm;
 pub mod rewind;
 pub mod settings;
 pub mod todo;
+pub mod plan;
 pub mod usage;
 
 use crate::state::{AppStateRest, Overlay};
@@ -95,6 +96,9 @@ pub fn render_overlay(
         Overlay::Todo => {
             todo::render(frame, overlay_area, block, state);
         }
+        Overlay::Plan => {
+            plan::render(frame, overlay_area, block, state);
+        }
         Overlay::Rewind => {
             rewind::render(frame, overlay_area, block, state);
         }

apps/interfaces/tui/src/view/overlays/plan.rs

@@ -0,0 +1,32 @@
+//! Overlay: Project Plan view — shows the full project plan content.
+use ratatui::style::{Modifier, Style};
+use ratatui::text::Span;
+use ratatui::widgets::{Block, Paragraph, Wrap};
+use ratatui::Frame;
+use crate::view::theme::Theme;
+
+/// Render the Project Plan overlay.
+pub fn render(
+    frame: &mut Frame,
+    area: ratatui::layout::Rect,
+    block: Block<'static>,
+    state: &crate::state::AppStateRest,
+) {
+    let block = block
+        .title(Span::styled(
+            " Project Plan ",
+            Style::default()
+                .fg(Theme::ACCENT_TEAL)
+                .add_modifier(Modifier::BOLD),
+        ))
+        .border_style(Style::default().fg(Theme::ACCENT_TEAL));
+    let content = if state.misc.plan_content.is_empty() {
+        "  No active project plan."
+    } else {
+        &state.misc.plan_content
+    };
+    let paragraph = Paragraph::new(content)
+        .block(block)
+        .wrap(Wrap { trim: false });
+    frame.render_widget(paragraph, area);
+}