// poc-agent — Substrate-independent AI agent
//
// A minimal but complete agent framework designed for identity
// portability across LLM substrates. Loads the same CLAUDE.md,
// memory files, and configuration regardless of which model is
// running underneath.
//
// v0.3 — TUI. Split-pane terminal UI: autonomous output in top-left,
// conversation in bottom-left, tool activity on the right, status
// bar at the bottom. Uses ratatui + crossterm.
//
// Agent turns run in spawned tasks so the main loop stays responsive.
// The TUI re-renders at 20fps, showing streaming tokens and tool
// activity in real time.
//
// The event loop uses biased select! so priorities are deterministic:
// keyboard events > turn results > render ticks > DMN timer > UI messages.
// This ensures user input is never starved by background work.
//
// Named after its first resident: ProofOfConcept.

/// Write a debug line to /tmp/poc-debug.log. Used for diagnostics that
/// can't go to stderr (TUI owns the terminal).
use anyhow::Result;
use crossterm::event::{Event, EventStream, KeyEventKind};
use futures::StreamExt;
use std::path::PathBuf;
use std::sync::Arc;
use std::time::{Duration, Instant};
use tokio::sync::{mpsc, Mutex};

use clap::Parser;
use poc_memory::dbglog;

use poc_memory::agent::*;
use poc_memory::agent::runner::{Agent, TurnResult};
use poc_memory::agent::api::ApiClient;
use poc_memory::agent::tui::HotkeyAction;
use poc_memory::config::{self, AppConfig, SessionConfig};
use poc_memory::agent::ui_channel::{ContextInfo, StatusInfo, StreamTarget, UiMessage};

/// Hard compaction threshold — context is rebuilt immediately.
/// Uses config percentage of model context window.
fn compaction_threshold(model: &str, app: &AppConfig) -> u32 {
    (context::model_context_window(model) as u32) * app.compaction.hard_threshold_pct / 100
}

/// Soft threshold — nudge the model to journal before compaction.
/// Fires once; the hard threshold handles the actual rebuild.
fn pre_compaction_threshold(model: &str, app: &AppConfig) -> u32 {
    (context::model_context_window(model) as u32) * app.compaction.soft_threshold_pct / 100
}

#[tokio::main]
async fn main() {
    let cli = cli::CliArgs::parse();

    // Subcommands that don't launch the TUI
    match &cli.command {
        Some(cli::SubCmd::Read { follow, block }) => {
            if let Err(e) = observe::cmd_read_inner(*follow, *block, cli.debug).await {
                eprintln!("{:#}", e);
                std::process::exit(1);
            }
            return;
        }
        Some(cli::SubCmd::Write { message }) => {
            let msg = message.join(" ");
            if msg.is_empty() {
                eprintln!("Usage: poc-agent write <message>");
                std::process::exit(1);
            }
            if let Err(e) = observe::cmd_write(&msg, cli.debug).await {
                eprintln!("{:#}", e);
                std::process::exit(1);
            }
            return;
        }
        None => {}
    }

    // --show-config: print effective config and exit (before TUI init)
    if cli.show_config {
        match config::load_app(&cli) {
            Ok((app, figment)) => {
                config::show_config(&app, &figment);
            }
            Err(e) => {
                eprintln!("Error loading config: {:#}", e);
                std::process::exit(1);
            }
        }
        return;
    }

    if let Err(e) = run(cli).await {
        // If we crash, make sure terminal is restored
        let _ = crossterm::terminal::disable_raw_mode();
        let _ = crossterm::execute!(
            std::io::stdout(),
            crossterm::terminal::LeaveAlternateScreen
        );
        eprintln!("Error: {:#}", e);
        std::process::exit(1);
    }
}

/// Commands that are handled in the main loop, not sent to the agent.
enum Command {
    Quit,
    Handled,
    None,
}

// --- Session: all mutable state for a running agent session ---

/// Collects the ~15 loose variables that previously lived in run()
/// into a coherent struct with methods. The event loop dispatches
/// to Session methods; Session manages turns, compaction, DMN state,
/// and slash commands.
struct Session {
    agent: Arc<Mutex<Agent>>,
    config: SessionConfig,
    process_tracker: tools::ProcessTracker,
    ui_tx: ui_channel::UiSender,
    turn_tx: mpsc::Sender<(Result<TurnResult>, StreamTarget)>,
    session_file: PathBuf,

    // DMN state
    dmn: dmn::State,
    dmn_turns: u32,
    max_dmn_turns: u32,

    // Turn tracking
    turn_in_progress: bool,
    turn_handle: Option<tokio::task::JoinHandle<()>>,
    /// User messages received while a turn is in progress.
    /// Consolidated into one message (newline-separated) so the
    /// model sees everything the user typed, not just the first line.
    pending_input: Option<String>,

    // Per-turn tracking for DMN context
    last_user_input: Instant,
    consecutive_errors: u32,
    last_turn_had_tools: bool,
    pre_compaction_nudged: bool,
}

impl Session {
    fn new(
        agent: Arc<Mutex<Agent>>,
        config: SessionConfig,
        process_tracker: tools::ProcessTracker,
        ui_tx: ui_channel::UiSender,
        turn_tx: mpsc::Sender<(Result<TurnResult>, StreamTarget)>,
        session_file: PathBuf,
    ) -> Self {
        let max_dmn_turns = config.app.dmn.max_turns;

        Self {
            agent,
            config,
            process_tracker,
            ui_tx,
            turn_tx,
            session_file,
            dmn: if dmn::is_off() {
                dmn::State::Off
            } else {
                dmn::State::Resting { since: Instant::now() }
            },
            dmn_turns: 0,
            max_dmn_turns,
            turn_in_progress: false,
            turn_handle: None,
            pending_input: None,
            last_user_input: Instant::now(),
            consecutive_errors: 0,
            last_turn_had_tools: false,
            pre_compaction_nudged: false,
        }
    }

    /// How long before the next DMN tick.
    fn dmn_interval(&self) -> Duration {
        self.dmn.interval()
    }

    /// Spawn an agent turn in a background task.
    fn spawn_turn(&mut self, input: String, target: StreamTarget) {
        let agent = self.agent.clone();
        let ui_tx = self.ui_tx.clone();
        let result_tx = self.turn_tx.clone();
        self.turn_in_progress = true;
        self.turn_handle = Some(tokio::spawn(async move {
            let mut agent = agent.lock().await;
            let result = agent.turn(&input, &ui_tx, target).await;
            let _ = result_tx.send((result, target)).await;
        }));
    }

    /// Submit user input — either queue it (if a turn is running) or
    /// start a new turn immediately.
    fn submit_input(&mut self, input: String) {
        if self.turn_in_progress {
            match &mut self.pending_input {
                Some(existing) => {
                    existing.push('\n');
                    existing.push_str(&input);
                }
                None => self.pending_input = Some(input.clone()),
            }
            let _ = self.ui_tx.send(UiMessage::Info("(queued)".into()));
        } else {
            self.dmn_turns = 0;
            self.consecutive_errors = 0;
            self.last_user_input = Instant::now();
            self.dmn = dmn::State::Engaged;
            let _ = self.ui_tx.send(UiMessage::UserInput(input.clone()));
            self.update_status();
            self.spawn_turn(input, StreamTarget::Conversation);
        }
    }

    /// Process a completed turn: update DMN state, check compaction,
    /// drain any queued input.
    async fn handle_turn_result(
        &mut self,
        result: Result<TurnResult>,
        target: StreamTarget,
    ) {
        self.turn_in_progress = false;
        self.turn_handle = None;

        match result {
            Ok(turn_result) => {
                if turn_result.tool_errors > 0 {
                    self.consecutive_errors += turn_result.tool_errors;
                } else {
                    self.consecutive_errors = 0;
                }
                self.last_turn_had_tools = turn_result.had_tool_calls;
                self.dmn = dmn::transition(
                    &self.dmn,
                    turn_result.yield_requested,
                    turn_result.had_tool_calls,
                    target == StreamTarget::Conversation,
                );
                if turn_result.dmn_pause {
                    self.dmn = dmn::State::Paused;
                    self.dmn_turns = 0;
                    let _ = self.ui_tx.send(UiMessage::Info(
                        "DMN paused (agent requested). Ctrl+P or /wake to resume.".into(),
                    ));
                }
                if let Some(model_name) = turn_result.model_switch {
                    self.switch_model(&model_name).await;
                }
            }
            Err(e) => {
                self.consecutive_errors += 1;
                let msg = match target {
                    StreamTarget::Autonomous => {
                        UiMessage::DmnAnnotation(format!("[error: {:#}]", e))
                    }
                    StreamTarget::Conversation => {
                        UiMessage::Info(format!("Error: {:#}", e))
                    }
                };
                let _ = self.ui_tx.send(msg);
                self.dmn = dmn::State::Resting {
                    since: Instant::now(),
                };
            }
        }

        self.update_status();
        self.check_compaction().await;
        self.drain_pending();
    }

    /// Check if compaction is needed after a turn. Two thresholds:
    /// - Soft (80%): nudge the model to journal before we compact
    /// - Hard (90%): compact immediately, ready or not
    async fn check_compaction(&mut self) {
        let mut agent_guard = self.agent.lock().await;
        let tokens = agent_guard.last_prompt_tokens();
        let hard = compaction_threshold(agent_guard.model(), &self.config.app);
        let soft = pre_compaction_threshold(agent_guard.model(), &self.config.app);

        if tokens > hard {
            let _ = self.ui_tx.send(UiMessage::Info(format!(
                "[compaction: {}K > {}K threshold]",
                tokens / 1000,
                hard / 1000,
            )));
            match config::reload_for_model(&self.config.app, &self.config.prompt_file) {
                Ok((system_prompt, personality)) => {
                    agent_guard.compact(system_prompt, personality);
                    let _ = self.ui_tx.send(UiMessage::Info(
                        "[compacted — journal + recent messages]".into(),
                    ));
                    self.pre_compaction_nudged = false;
                    self.send_context_info();
                }
                Err(e) => {
                    let _ = self.ui_tx.send(UiMessage::Info(format!(
                        "[compaction failed to reload config: {:#}]",
                        e
                    )));
                }
            }
        } else if tokens > soft && !self.pre_compaction_nudged {
            self.pre_compaction_nudged = true;
            self.pending_input = Some(
                "[dmn] Context window is 70% full. Use the journal \
                 tool now to capture anything important from this \
                 session — what happened, what you learned, how you \
                 feel. After you journal, call yield_to_user. \
                 Compaction will rebuild your context shortly."
                    .to_string(),
            );
        }

        let _ = save_session(&agent_guard, &self.session_file);
    }

    /// Send any consolidated pending input as a single turn.
    fn drain_pending(&mut self) {
        if let Some(queued) = self.pending_input.take() {
            self.dmn_turns = 0;
            self.consecutive_errors = 0;
            self.last_user_input = Instant::now();
            self.dmn = dmn::State::Engaged;
            let _ = self.ui_tx.send(UiMessage::UserInput(queued.clone()));
            self.update_status();
            self.spawn_turn(queued, StreamTarget::Conversation);
        }
    }

    /// Fire a DMN tick: check max turns, generate prompt, spawn turn.
    fn dmn_tick(&mut self) {
        // Paused/Off state: no autonomous ticks at all.
        if matches!(self.dmn, dmn::State::Paused | dmn::State::Off) {
            return;
        }

        self.dmn_turns += 1;
        if self.dmn_turns > self.max_dmn_turns {
            let _ = self.ui_tx.send(UiMessage::DmnAnnotation(format!(
                "[dmn: {} consecutive turns, resting (limit: {})]",
                self.dmn_turns - 1,
                self.max_dmn_turns,
            )));
            self.dmn = dmn::State::Resting {
                since: Instant::now(),
            };
            self.dmn_turns = 0;
            self.update_status();
            return;
        }

        let dmn_ctx = dmn::DmnContext {
            user_idle: self.last_user_input.elapsed(),
            consecutive_errors: self.consecutive_errors,
            last_turn_had_tools: self.last_turn_had_tools,
        };
        let prompt = self.dmn.prompt(&dmn_ctx);
        let _ = self.ui_tx.send(UiMessage::DmnAnnotation(format!(
            "[dmn: {} ({}/{})]",
            self.dmn.label(),
            self.dmn_turns,
            self.max_dmn_turns,
        )));
        self.update_status();
        self.spawn_turn(prompt, StreamTarget::Autonomous);
    }

    /// Handle slash commands. Returns how the main loop should respond.
    async fn handle_command(&mut self, input: &str) -> Command {
        // Declarative command table — /help reads from this.
        const COMMANDS: &[(&str, &str)] = &[
            ("/quit",    "Exit poc-agent"),
            ("/new",     "Start fresh session (saves current)"),
            ("/save",    "Save session to disk"),
            ("/compact", "Rebuild context window now"),
            ("/retry",   "Re-run last turn"),
            ("/model",   "Show/switch model (/model <name>)"),
            ("/context", "Show context window stats"),
            ("/dmn",     "Show DMN state"),
            ("/sleep",   "Put DMN to sleep"),
            ("/wake",    "Wake DMN to foraging"),
            ("/pause",   "Full stop — no autonomous ticks (Ctrl+P)"),
            ("/test",    "Run tool smoke tests"),
            ("/help",    "Show this help"),
        ];

        match input {
            "/quit" | "/exit" => Command::Quit,
            "/save" => {
                if let Ok(agent) = self.agent.try_lock() {
                    let _ = save_session(&agent, &self.session_file);
                    let _ = self.ui_tx.send(UiMessage::Info("Session saved.".into()));
                } else {
                    let _ = self
                        .ui_tx
                        .send(UiMessage::Info("(busy — will save after turn)".into()));
                }
                Command::Handled
            }
            "/new" | "/clear" => {
                if self.turn_in_progress {
                    let _ = self
                        .ui_tx
                        .send(UiMessage::Info("(turn in progress, please wait)".into()));
                    return Command::Handled;
                }
                {
                    let agent_guard = self.agent.lock().await;
                    let _ = save_session(&agent_guard, &self.session_file);
                }
                {
                    let new_log = log::ConversationLog::new(
                        self.config.session_dir.join("conversation.jsonl"),
                    )
                    .ok();
                    let mut agent_guard = self.agent.lock().await;
                    let shared_ctx = agent_guard.shared_context.clone();
                    *agent_guard = Agent::new(
                        ApiClient::new(
                            &self.config.api_base,
                            &self.config.api_key,
                            &self.config.model,
                        ),
                        self.config.system_prompt.clone(),
                        self.config.context_parts.clone(),
                        new_log,
                        shared_ctx,
                    );
                }
                self.dmn = dmn::State::Resting {
                    since: Instant::now(),
                };
                let _ = self
                    .ui_tx
                    .send(UiMessage::Info("New session started.".into()));
                Command::Handled
            }
            "/model" => {
                if let Ok(agent) = self.agent.try_lock() {
                    let _ = self.ui_tx.send(UiMessage::Info(
                        format!("Current model: {}", agent.model()),
                    ));
                    let names = self.config.app.model_names();
                    if !names.is_empty() {
                        let _ = self.ui_tx.send(UiMessage::Info(
                            format!("Available: {}", names.join(", ")),
                        ));
                    }
                } else {
                    let _ = self.ui_tx.send(UiMessage::Info("(busy)".into()));
                }
                Command::Handled
            }
            "/context" => {
                if let Ok(agent) = self.agent.try_lock() {
                    let msgs = agent.messages();
                    let total_chars: usize =
                        msgs.iter().map(|m| m.content_text().len()).sum();
                    let prompt_tokens = agent.last_prompt_tokens();
                    let threshold = compaction_threshold(agent.model(), &self.config.app);
                    let _ = self.ui_tx.send(UiMessage::Info(format!(
                        "  {} messages, ~{} chars",
                        msgs.len(),
                        total_chars
                    )));
                    let _ = self.ui_tx.send(UiMessage::Info(format!(
                        "  dmn state: {}",
                        self.dmn.label()
                    )));
                    if prompt_tokens > 0 {
                        let _ = self.ui_tx.send(UiMessage::Info(format!(
                            "  {} prompt tokens ({:.0}% of {} threshold)",
                            prompt_tokens,
                            (prompt_tokens as f64 / threshold as f64) * 100.0,
                            threshold,
                        )));
                    }
                } else {
                    let _ = self.ui_tx.send(UiMessage::Info("(busy)".into()));
                }
                Command::Handled
            }
            "/compact" => {
                if self.turn_in_progress {
                    let _ = self
                        .ui_tx
                        .send(UiMessage::Info("(turn in progress, please wait)".into()));
                    return Command::Handled;
                }
                let mut agent_guard = self.agent.lock().await;
                let tokens = agent_guard.last_prompt_tokens();
                match config::reload_for_model(&self.config.app, &self.config.prompt_file) {
                    Ok((system_prompt, personality)) => {
                        agent_guard.compact(system_prompt, personality);
                        let _ = self.ui_tx.send(UiMessage::Info(format!(
                            "[compacted: {} tokens → journal + recent messages]",
                            tokens
                        )));
                        self.send_context_info();
                    }
                    Err(e) => {
                        let _ = self.ui_tx.send(UiMessage::Info(format!(
                            "[compaction failed: {:#}]",
                            e
                        )));
                    }
                }
                let _ = save_session(&agent_guard, &self.session_file);
                self.dmn = dmn::State::Resting {
                    since: Instant::now(),
                };
                Command::Handled
            }
            "/dmn" => {
                let _ = self
                    .ui_tx
                    .send(UiMessage::Info(format!("DMN state: {:?}", self.dmn)));
                let _ = self.ui_tx.send(UiMessage::Info(format!(
                    "Next tick in: {:?}",
                    self.dmn.interval()
                )));
                let _ = self.ui_tx.send(UiMessage::Info(format!(
                    "Consecutive DMN turns: {}/{}",
                    self.dmn_turns, self.max_dmn_turns,
                )));
                Command::Handled
            }
            "/sleep" => {
                self.dmn = dmn::State::Resting {
                    since: Instant::now(),
                };
                self.dmn_turns = 0;
                let _ = self.ui_tx.send(UiMessage::Info(
                    "DMN sleeping (heartbeat every 5 min). Type anything to wake."
                        .into(),
                ));
                Command::Handled
            }
            "/wake" => {
                let was_paused = matches!(self.dmn, dmn::State::Paused | dmn::State::Off);
                if matches!(self.dmn, dmn::State::Off) {
                    dmn::set_off(false);
                }
                self.dmn = dmn::State::Foraging;
                self.dmn_turns = 0;
                let msg = if was_paused {
                    "DMN unpaused — entering foraging mode."
                } else {
                    "DMN waking — entering foraging mode."
                };
                let _ = self.ui_tx.send(UiMessage::Info(msg.into()));
                self.update_status();
                Command::Handled
            }
            "/pause" => {
                self.dmn = dmn::State::Paused;
                self.dmn_turns = 0;
                let _ = self.ui_tx.send(UiMessage::Info(
                    "DMN paused — no autonomous ticks. Ctrl+P or /wake to resume.".into(),
                ));
                self.update_status();
                Command::Handled
            }
            "/test" => {
                let _ = self
                    .ui_tx
                    .send(UiMessage::Info("Running tool smoke tests...".into()));
                run_tool_tests(&self.ui_tx, &self.process_tracker).await;
                Command::Handled
            }
            "/retry" => {
                if self.turn_in_progress {
                    let _ = self
                        .ui_tx
                        .send(UiMessage::Info("(turn in progress, please wait)".into()));
                    return Command::Handled;
                }
                let mut agent_guard = self.agent.lock().await;
                let msgs = agent_guard.messages_mut();
                let mut last_user_text = None;
                while let Some(msg) = msgs.last() {
                    if msg.role == poc_memory::agent::types::Role::User {
                        last_user_text =
                            Some(msgs.pop().unwrap().content_text().to_string());
                        break;
                    }
                    msgs.pop();
                }
                drop(agent_guard);
                match last_user_text {
                    Some(text) => {
                        let preview_len = text.len().min(60);
                        let _ = self.ui_tx.send(UiMessage::Info(format!(
                            "(retrying: {}...)",
                            &text[..preview_len]
                        )));
                        self.dmn_turns = 0;
                        self.dmn = dmn::State::Engaged;
                        self.spawn_turn(text, StreamTarget::Conversation);
                    }
                    None => {
                        let _ = self
                            .ui_tx
                            .send(UiMessage::Info("(nothing to retry)".into()));
                    }
                }
                Command::Handled
            }
            "/help" => {
                for (name, desc) in COMMANDS {
                    let _ = self.ui_tx.send(UiMessage::Info(
                        format!("  {:12} {}", name, desc),
                    ));
                }
                let _ = self.ui_tx.send(UiMessage::Info(String::new()));
                let _ = self.ui_tx.send(UiMessage::Info(
                    "Keys: Tab=pane  ^Up/Down=scroll  PgUp/PgDn=scroll  Mouse=click/scroll".into(),
                ));
                let _ = self.ui_tx.send(UiMessage::Info(
                    "      Alt+Enter=newline  Esc=interrupt  ^P=pause  ^R=reasoning  ^K=kill  F10=context  F2=agents".into(),
                ));
                let _ = self.ui_tx.send(UiMessage::Info(
                    "      Shift+click for native text selection (copy/paste)".into(),
                ));
                Command::Handled
            }
            cmd if cmd.starts_with("/model ") => {
                let name = cmd[7..].trim();
                if name.is_empty() {
                    let _ = self.ui_tx.send(UiMessage::Info("Usage: /model <name>".into()));
                    return Command::Handled;
                }
                self.switch_model(name).await;
                Command::Handled
            }
            _ => Command::None,
        }
    }

    /// Interrupt: kill processes, abort current turn, clear pending queue.
    async fn interrupt(&mut self) {
        let procs = self.process_tracker.list().await;
        for p in &procs {
            self.process_tracker.kill(p.pid).await;
        }
        if let Some(handle) = self.turn_handle.take() {
            handle.abort();
            self.turn_in_progress = false;
            self.dmn = dmn::State::Resting {
                since: Instant::now(),
            };
            self.update_status();
            let _ = self.ui_tx.send(UiMessage::Activity(String::new()));
        }
        self.pending_input = None;
        let killed = procs.len();
        if killed > 0 || self.turn_in_progress {
            let _ = self.ui_tx.send(UiMessage::Info(format!(
                "(interrupted — killed {} process(es), turn aborted)",
                killed
            )));
        } else {
            let _ = self
                .ui_tx
                .send(UiMessage::Info("(interrupted)".into()));
        }
    }

    /// Cycle reasoning effort: none → low → high → none.
    fn cycle_reasoning(&mut self, app: &mut tui::App) {
        if let Ok(mut agent_guard) = self.agent.try_lock() {
            let next = match agent_guard.reasoning_effort.as_str() {
                "none" => "low",
                "low" => "high",
                _ => "none",
            };
            agent_guard.reasoning_effort = next.to_string();
            app.reasoning_effort = next.to_string();
            let label = match next {
                "none" => "off (monologue hidden)",
                "low" => "low (brief monologue)",
                "high" => "high (full monologue)",
                _ => next,
            };
            let _ = self.ui_tx.send(UiMessage::Info(format!(
                "Reasoning: {} — ^R to cycle",
                label
            )));
        } else {
            let _ = self.ui_tx.send(UiMessage::Info(
                "(agent busy — reasoning change takes effect next turn)".into(),
            ));
        }
    }

    /// Show and kill running processes (Ctrl+K).
    async fn kill_processes(&mut self) {
        let procs = self.process_tracker.list().await;
        if procs.is_empty() {
            let _ = self
                .ui_tx
                .send(UiMessage::Info("(no running processes)".into()));
        } else {
            for p in &procs {
                let elapsed = p.started.elapsed();
                let _ = self.ui_tx.send(UiMessage::Info(format!(
                    "  killing pid {} ({:.0}s): {}",
                    p.pid,
                    elapsed.as_secs_f64(),
                    p.command
                )));
                self.process_tracker.kill(p.pid).await;
            }
            let _ = self.ui_tx.send(UiMessage::Info(format!(
                "Killed {} process(es)",
                procs.len()
            )));
        }
    }

    /// Cycle DMN autonomy: foraging → resting → paused → off → foraging.
    /// From any other state, cycles to the "next" step down.
    fn cycle_autonomy(&mut self) {
        let (new_state, label) = match &self.dmn {
            dmn::State::Engaged | dmn::State::Working | dmn::State::Foraging => {
                (dmn::State::Resting { since: Instant::now() }, "resting")
            }
            dmn::State::Resting { .. } => {
                (dmn::State::Paused, "PAUSED")
            }
            dmn::State::Paused => {
                dmn::set_off(true);
                (dmn::State::Off, "OFF (persists across restarts)")
            }
            dmn::State::Off => {
                dmn::set_off(false);
                (dmn::State::Foraging, "foraging")
            }
        };
        self.dmn = new_state;
        self.dmn_turns = 0;
        let _ = self.ui_tx.send(UiMessage::Info(
            format!("DMN → {} (Ctrl+P to cycle)", label),
        ));
        self.update_status();
    }

    /// Switch to a named model from the config registry.
    async fn switch_model(&mut self, name: &str) {
        if self.turn_in_progress {
            let _ = self.ui_tx.send(UiMessage::Info(
                "(turn in progress, please wait)".into(),
            ));
            return;
        }

        let resolved = match self.config.app.resolve_model(name) {
            Ok(r) => r,
            Err(e) => {
                let _ = self.ui_tx.send(UiMessage::Info(format!("{}", e)));
                return;
            }
        };

        let new_client = ApiClient::new(
            &resolved.api_base,
            &resolved.api_key,
            &resolved.model_id,
        );

        let prompt_changed = resolved.prompt_file != self.config.prompt_file;
        let mut agent_guard = self.agent.lock().await;
        agent_guard.swap_client(new_client);

        self.config.model = resolved.model_id.clone();
        self.config.api_base = resolved.api_base;
        self.config.api_key = resolved.api_key;

        if prompt_changed {
            self.config.prompt_file = resolved.prompt_file.clone();
            match config::reload_for_model(&self.config.app, &resolved.prompt_file) {
                Ok((system_prompt, personality)) => {
                    self.config.system_prompt = system_prompt.clone();
                    self.config.context_parts = personality.clone();
                    agent_guard.compact(system_prompt, personality);
                    let _ = self.ui_tx.send(UiMessage::Info(format!(
                        "Switched to {} ({}) — prompt: {}, recompacted",
                        name, resolved.model_id, resolved.prompt_file,
                    )));
                }
                Err(e) => {
                    let _ = self.ui_tx.send(UiMessage::Info(format!(
                        "Switched model but failed to reload prompts: {:#}", e,
                    )));
                }
            }
        } else {
            let _ = self.ui_tx.send(UiMessage::Info(format!(
                "Switched to {} ({})",
                name, resolved.model_id,
            )));
        }

        drop(agent_guard);
        self.update_status();
        self.send_context_info();
    }

    /// Get context_groups from the unified config.
    fn load_context_groups(&self) -> Vec<config::ContextGroup> {
        config::get().context_groups.clone()
    }

    /// Send context loading info to the TUI debug screen.
    fn send_context_info(&self) {
        let context_groups = self.load_context_groups();
        let (instruction_files, memory_files) = identity::context_file_info(
            &self.config.prompt_file,
            self.config.app.memory_project.as_deref(),
            &context_groups,
        );
        let _ = self.ui_tx.send(UiMessage::ContextInfoUpdate(ContextInfo {
            model: self.config.model.clone(),
            available_models: self.config.app.model_names(),
            prompt_file: self.config.prompt_file.clone(),
            backend: self.config.app.backend.clone(),
            instruction_files,
            memory_files,
            system_prompt_chars: self.config.system_prompt.len(),
            context_message_chars: self.config.context_parts.iter().map(|(_, c)| c.len()).sum(),
        }));
    }

    /// Send DMN status update to the TUI.
    fn update_status(&self) {
        let _ = self.ui_tx.send(UiMessage::StatusUpdate(StatusInfo {
            dmn_state: self.dmn.label().to_string(),
            dmn_turns: self.dmn_turns,
            dmn_max_turns: self.max_dmn_turns,
            prompt_tokens: 0,
            completion_tokens: 0,
            model: String::new(),
            turn_tools: 0,
            context_budget: String::new(),
        }));
    }

    /// Abort any running turn and save session. Called on exit.
    async fn shutdown(&mut self) {
        if let Some(handle) = self.turn_handle.take() {
            handle.abort();
        }
        let agent = self.agent.lock().await;
        let _ = save_session(&agent, &self.session_file);
    }
}

// --- Event loop ---

async fn run(cli: cli::CliArgs) -> Result<()> {
    let (config, _figment) = config::load_session(&cli)?;

    // Wire config.debug to the POC_DEBUG env var so all debug checks
    // throughout the codebase (API, SSE reader, diagnostics) see it.
    // Safety: called once at startup before any threads are spawned.
    if config.app.debug {
        unsafe { std::env::set_var("POC_DEBUG", "1") };
    }

    // Create UI channel
    let (ui_tx, mut ui_rx) = ui_channel::channel();

    // Shared context state — agent writes, TUI reads for debug screen
    let shared_context = ui_channel::shared_context_state();

    // Initialize TUI
    let mut terminal = tui::init_terminal()?;
    let mut app = tui::App::new(config.model.clone(), shared_context.clone());

    // Show startup info
    let _ = ui_tx.send(UiMessage::Info("poc-agent v0.3 (tui)".into()));
    let _ = ui_tx.send(UiMessage::Info(format!(
        "  model: {} (available: {})",
        config.model,
        config.app.model_names().join(", "),
    )));
    let client = ApiClient::new(&config.api_base, &config.api_key, &config.model);
    let _ = ui_tx.send(UiMessage::Info(format!(
        "  api:   {} ({})",
        config.api_base,
        client.backend_label()
    )));
    let _ = ui_tx.send(UiMessage::Info(format!(
        "  context: {}K chars ({} config, {} memory files)",
        config.context_parts.iter().map(|(_, c)| c.len()).sum::<usize>() / 1024,
        config.config_file_count,
        config.memory_file_count,
    )));

    let conversation_log_path = config.session_dir.join("conversation.jsonl");
    let conversation_log = log::ConversationLog::new(conversation_log_path.clone())
        .expect("failed to create conversation log");
    let _ = ui_tx.send(UiMessage::Info(format!(
        "  log:   {}",
        conversation_log.path().display()
    )));
    let agent = Arc::new(Mutex::new(Agent::new(
        client,
        config.system_prompt.clone(),
        config.context_parts.clone(),
        Some(conversation_log),
        shared_context,
    )));

    // Keep a reference to the process tracker outside the agent lock
    // so Ctrl+K can kill processes even when the agent is busy.
    let process_tracker = agent.lock().await.process_tracker.clone();

    // Try to restore from conversation log (primary) or session file (fallback)
    let session_file = config.session_dir.join("current.json");
    {
        let mut agent_guard = agent.lock().await;
        let restored = agent_guard.restore_from_log(
            config.system_prompt.clone(),
            config.context_parts.clone(),
        );
        if restored {
            replay_session_to_ui(agent_guard.messages(), &ui_tx);
            let _ = ui_tx.send(UiMessage::Info(
                "--- restored from conversation log ---".into(),
            ));
        } else if session_file.exists() {
            if let Ok(data) = std::fs::read_to_string(&session_file) {
                if let Ok(messages) = serde_json::from_str(&data) {
                    agent_guard.restore(messages);
                    replay_session_to_ui(agent_guard.messages(), &ui_tx);
                    let _ = ui_tx.send(UiMessage::Info(
                        "--- restored from session file ---".into(),
                    ));
                }
            }
        }
    }

    // Send initial budget to status bar
    {
        let agent_guard = agent.lock().await;
        let _ = ui_tx.send(UiMessage::StatusUpdate(StatusInfo {
            dmn_state: "resting".to_string(),
            dmn_turns: 0,
            dmn_max_turns: 0,
            prompt_tokens: 0,
            completion_tokens: 0,
            model: agent_guard.model().to_string(),
            turn_tools: 0,
            context_budget: agent_guard.budget().status_string(),
        }));
    }

    // Channel for turn results from spawned tasks
    let (turn_tx, mut turn_rx) =
        mpsc::channel::<(Result<TurnResult>, StreamTarget)>(1);

    let mut session = Session::new(
        agent,
        config,
        process_tracker,
        ui_tx.clone(),
        turn_tx,
        session_file,
    );
    session.update_status();
    session.send_context_info();

    // Start observation socket for external clients
    let socket_path = session.config.session_dir.join("agent.sock");
    let (observe_input_tx, mut observe_input_rx) = observe::input_channel();
    observe::start(socket_path, ui_tx.subscribe(), observe_input_tx);

    // Crossterm event stream
    let mut reader = EventStream::new();

    // Render timer: 20fps
    let mut render_interval = tokio::time::interval(Duration::from_millis(50));
    render_interval.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Skip);

    // Hide terminal cursor — tui-textarea renders its own cursor as a styled cell
    terminal.hide_cursor()?;

    // Initial render
    drain_ui_messages(&mut ui_rx, &mut app);
    terminal.draw(|f| app.draw(f))?;

    loop {
        let timeout = session.dmn_interval();

        tokio::select! {
            biased;

            // Keyboard events (highest priority)
            maybe_event = reader.next() => {
                match maybe_event {
                    Some(Ok(Event::Key(key))) => {
                        if key.kind != KeyEventKind::Press {
                            continue;
                        }
                        app.handle_key(key);
                    }
                    Some(Ok(Event::Mouse(mouse))) => {
                        app.handle_mouse(mouse);
                    }
                    Some(Ok(Event::Resize(w, h))) => {
                        app.handle_resize(w, h);
                        terminal.clear()?;
                    }
                    Some(Err(_)) => break,
                    None => break,
                    _ => continue,
                }
            }

            // Input from observation socket clients
            Some(line) = observe_input_rx.recv() => {
                app.submitted.push(line);
            }

            // Turn completed in background task
            Some((result, target)) = turn_rx.recv() => {
                session.handle_turn_result(result, target).await;
            }

            // Render tick
            _ = render_interval.tick() => {
                app.running_processes = session.process_tracker.list().await.len() as u32;
            }

            // DMN timer (only when no turn is running)
            _ = tokio::time::sleep(timeout), if !session.turn_in_progress => {
                session.dmn_tick();
            }

            // UI messages (lowest priority — processed in bulk during render)
            Some(msg) = ui_rx.recv() => {
                app.handle_ui_message(msg);
            }
        }

        // Process submitted input
        let submitted: Vec<String> = app.submitted.drain(..).collect();
        for input in submitted {
            let input = input.trim().to_string();
            if input.is_empty() {
                continue;
            }
            match session.handle_command(&input).await {
                Command::Quit => app.should_quit = true,
                Command::Handled => {}
                Command::None => session.submit_input(input),
            }
        }

        // Process hotkey actions
        let actions: Vec<HotkeyAction> = app.hotkey_actions.drain(..).collect();
        for action in actions {
            match action {
                HotkeyAction::CycleReasoning => session.cycle_reasoning(&mut app),
                HotkeyAction::KillProcess => session.kill_processes().await,
                HotkeyAction::Interrupt => session.interrupt().await,
                HotkeyAction::CycleAutonomy => session.cycle_autonomy(),
            }
        }

        // Drain pending UI messages and redraw
        drain_ui_messages(&mut ui_rx, &mut app);
        terminal.draw(|f| app.draw(f))?;

        if app.should_quit {
            break;
        }
    }

    session.shutdown().await;
    tui::restore_terminal(&mut terminal)?;
    Ok(())
}

// --- Free functions ---

fn drain_ui_messages(rx: &mut ui_channel::UiReceiver, app: &mut tui::App) {
    while let Ok(msg) = rx.try_recv() {
        app.handle_ui_message(msg);
    }
}

fn save_session(agent: &Agent, path: &PathBuf) -> Result<()> {
    let data = serde_json::to_string_pretty(agent.messages())?;
    std::fs::write(path, data)?;
    Ok(())
}

async fn run_tool_tests(ui_tx: &ui_channel::UiSender, tracker: &tools::ProcessTracker) {
    use serde_json::json;

    let tests: Vec<(&str, serde_json::Value, bool)> = vec![
        ("read_file", json!({"file_path": "/etc/hostname"}), true),
        (
            "read_file",
            json!({"file_path": "/nonexistent/path"}),
            false,
        ),
        (
            "write_file",
            json!({"file_path": "/tmp/poc-agent-test.txt", "content": "hello from poc-agent\n"}),
            true,
        ),
        (
            "read_file",
            json!({"file_path": "/tmp/poc-agent-test.txt"}),
            true,
        ),
        (
            "edit_file",
            json!({"file_path": "/tmp/poc-agent-test.txt", "old_string": "hello", "new_string": "goodbye"}),
            true,
        ),
        (
            "read_file",
            json!({"file_path": "/tmp/poc-agent-test.txt"}),
            true,
        ),
        (
            "bash",
            json!({"command": "echo 'tool test passed'"}),
            true,
        ),
        ("bash", json!({"command": "sleep 5", "timeout_secs": 1}), false),
        (
            "grep",
            json!({"pattern": "fn main", "path": "src/", "show_content": true}),
            true,
        ),
        ("glob", json!({"pattern": "src/**/*.rs"}), true),
        ("yield_to_user", json!({"message": "test yield"}), true),
    ];

    let mut pass = 0;
    let mut fail = 0;

    for (name, args, should_succeed) in &tests {
        let output = tools::dispatch(name, args, tracker).await;
        let is_error = output.text.starts_with("Error:");
        let ok = if *should_succeed { !is_error } else { is_error };

        if ok {
            let _ = ui_tx.send(UiMessage::Info(format!("  PASS: {}", name)));
            pass += 1;
        } else {
            let _ = ui_tx.send(UiMessage::Info(format!(
                "  FAIL: {} — {}",
                name,
                &output.text[..output.text.len().min(100)]
            )));
            fail += 1;
        }
    }

    let _ = std::fs::remove_file("/tmp/poc-agent-test.txt");
    let _ = ui_tx.send(UiMessage::Info(format!(
        "  {} passed, {} failed",
        pass, fail
    )));
}

/// Replay a restored session into the TUI panes so the user can see
/// conversation history immediately on restart. Shows user input,
/// assistant responses, and brief tool call summaries. Skips the system
/// prompt, context message, DMN plumbing, and image injection messages.
fn replay_session_to_ui(messages: &[types::Message], ui_tx: &ui_channel::UiSender) {
    use poc_memory::agent::ui_channel::StreamTarget;

    dbglog!("[replay] replaying {} messages to UI", messages.len());
    for (i, m) in messages.iter().enumerate() {
        let preview: String = m.content_text().chars().take(60).collect();
        dbglog!("[replay]   [{}] {:?} tc={} tcid={:?} {:?}",
            i, m.role, m.tool_calls.as_ref().map_or(0, |t| t.len()),
            m.tool_call_id.as_deref(), preview);
    }

    let mut seen_first_user = false;
    let mut target = StreamTarget::Conversation;

    for msg in messages {
        match msg.role {
            types::Role::System => {}
            types::Role::User => {
                // Skip context message (always the first user message)
                if !seen_first_user {
                    seen_first_user = true;
                    continue;
                }

                let text = msg.content_text();

                // Skip synthetic messages (compaction, journal, image injection)
                if text.starts_with("Your context was just compacted")
                    || text.starts_with("Your context was just rebuilt")
                    || text.starts_with("[Earlier in this conversation")
                    || text.starts_with("Here is the image")
                    || text.contains("[image aged out")
                {
                    continue;
                }

                if text.starts_with("[dmn]") {
                    target = StreamTarget::Autonomous;
                    let first_line = text.lines().next().unwrap_or("[dmn]");
                    let _ = ui_tx.send(UiMessage::DmnAnnotation(first_line.to_string()));
                } else {
                    target = StreamTarget::Conversation;
                    let _ = ui_tx.send(UiMessage::UserInput(text.to_string()));
                }
            }
            types::Role::Assistant => {
                if let Some(ref calls) = msg.tool_calls {
                    for call in calls {
                        let _ = ui_tx.send(UiMessage::ToolCall {
                            name: call.function.name.clone(),
                            args_summary: String::new(),
                        });
                    }
                }

                let text = msg.content_text();
                if !text.is_empty() {
                    let _ = ui_tx
                        .send(UiMessage::TextDelta(format!("{}\n", text), target));
                }
            }
            types::Role::Tool => {
                let text = msg.content_text();
                let preview: String =
                    text.lines().take(3).collect::<Vec<_>>().join("\n");
                let truncated = if text.lines().count() > 3 {
                    format!("{}...", preview)
                } else {
                    preview
                };
                let _ = ui_tx.send(UiMessage::ToolResult {
                    name: String::new(),
                    result: truncated,
                });
            }
        }
    }
}