capo-agent 0.1.0

#![cfg_attr(test, allow(clippy::expect_used, clippy::unwrap_used))]

use std::collections::VecDeque;
use std::path::PathBuf;
use std::sync::{Arc, Mutex, MutexGuard};

use futures::{Stream, StreamExt};
use motosan_agent_loop::{
    AgentEvent, AgentOp, AgentSession, AgentStreamItem, AutocompactConfig, AutocompactExtension,
    CoreEvent, Engine, LlmClient, SessionStore,
};
use motosan_agent_tool::ToolContext;
use tokio::sync::mpsc;

use crate::agent::build_system_prompt;
use crate::config::Config;
use crate::error::{AppError, Result};
use crate::events::{ProgressChunk, UiEvent, UiToolResult};
use crate::llm::build_llm_client;
use crate::permissions::{NoOpPermissionGate, PermissionGate};
use crate::tools::{builtin_tools, SharedCancelToken, ToolCtx, ToolProgressChunk};

pub struct App {
    // Wrapped in Arc because `AgentSession::Drop` sets the shared `closed`
    // flag, which would otherwise mark the session closed every time the
    // cloned session captured by `send_user_message`'s stream is dropped.
    // Arc keeps a single live owner so close only fires when the App itself
    // is dropped.
    session: Arc<AgentSession>,
    config: Config,
    cancel_token: SharedCancelToken,
    progress_rx: Arc<tokio::sync::Mutex<mpsc::Receiver<ToolProgressChunk>>>,
    next_tool_id: Arc<Mutex<ToolCallTracker>>,
    skills: Arc<Vec<crate::skills::Skill>>,
    mcp_servers: Vec<(String, Arc<dyn motosan_agent_loop::mcp::McpServer>)>,
    pub(crate) session_cache: Arc<crate::permissions::SessionCache>,
}

impl App {
    pub fn config(&self) -> &Config {
        &self.config
    }

    /// Request graceful cancellation of the currently-running turn (if any).
    /// Safe to call from any task; the engine observes the token and halts
    /// at the next safe point.
    pub fn cancel(&self) {
        self.cancel_token.cancel();
    }

    /// Exposes the session cache so front-ends can write "Allow for session"
    /// decisions resolved by the user. Exposed as `Arc` so callers can drop
    /// their reference freely.
    pub fn permissions_cache(&self) -> Arc<crate::permissions::SessionCache> {
        Arc::clone(&self.session_cache)
    }

    /// M3: the underlying motosan session id. Always populated; ephemeral
    /// sessions use a synthetic id internally.
    pub fn session_id(&self) -> &str {
        self.session.session_id()
    }

    /// M3: snapshot of the session's persisted message history. Used by the
    /// binary on `--continue` / `--session` to seed the TUI transcript so
    /// the user can see what was said in prior runs. `AgentSession::resume`
    /// already populates this internally for the *agent* to use as context
    /// on the next turn; this method exposes it so the *front-end* can
    /// render it too. Returns motosan's `Vec<Message>` verbatim (callers
    /// decide how to map roles → UI blocks; system messages are typically
    /// dropped because they're the prompt, not transcript).
    pub async fn session_history(
        &self,
    ) -> motosan_agent_loop::Result<Vec<motosan_agent_loop::Message>> {
        self.session.history().await
    }

    /// M4 Phase B: disconnect every registered MCP server (2s per-server
    /// timeout, best-effort). Call from the binary's ctrl-C handler.
    pub async fn disconnect_mcp(&self) {
        for (name, server) in &self.mcp_servers {
            let _ =
                tokio::time::timeout(std::time::Duration::from_secs(2), server.disconnect()).await;
            tracing::debug!(target: "mcp", server = %name, "disconnected");
        }
    }

    pub fn send_user_message(&self, text: String) -> impl Stream<Item = UiEvent> + Send + 'static {
        let session = Arc::clone(&self.session);
        let skills = Arc::clone(&self.skills);
        let cancel_token = self.cancel_token.clone();
        let tracker = Arc::clone(&self.next_tool_id);
        let progress = Arc::clone(&self.progress_rx);

        async_stream::stream! {
            // Single-turn guard (M2 contract preserved).
            let mut progress_guard = match progress.try_lock() {
                Ok(guard) => guard,
                Err(_) => {
                    yield UiEvent::Error(
                        "another turn is already running; capo is single-turn-per-App".into(),
                    );
                    return;
                }
            };

            // Reset cancel token for THIS turn.
            let cancel = cancel_token.reset();

            yield UiEvent::AgentTurnStarted;
            yield UiEvent::AgentThinking;

            // Load history from the session (empty for fresh / ephemeral).
            let history = match session.history().await {
                Ok(h) => h,
                Err(err) => {
                    yield UiEvent::Error(format!("session.history failed: {err}"));
                    return;
                }
            };
            let mut messages = history;
            let text = crate::skills::expand::expand_skill_command(&text, &skills);
            messages.push(motosan_agent_loop::Message::user(&text));

            // Start the turn (gives us a TurnHandle with stream + previous_len + ops_tx).
            let handle = match session.start_turn(messages).await {
                Ok(h) => h,
                Err(err) => {
                    yield UiEvent::Error(format!("session.start_turn failed: {err}"));
                    return;
                }
            };
            let previous_len = handle.previous_len;
            let epoch = handle.epoch;
            let ops_tx = handle.ops_tx.clone();
            let mut agent_stream = handle.stream;

            // Bridge our SharedCancelToken to motosan's AgentOp::Interrupt.
            //
            // `AgentSession::start_turn` does NOT take a CancellationToken —
            // the engine's cancel-token path used in M2's direct `.run().cancel(tok)`
            // is bypassed when going through AgentSession. The control plane is
            // `ops_tx`. We spawn a tiny task that waits on `cancel.cancelled()`
            // and forwards an `Interrupt` op when fired.
            let interrupt_bridge = tokio::spawn(async move {
                cancel.cancelled().await;
                let _ = ops_tx.send(AgentOp::Interrupt).await;
            });

            // Drain events.
            let mut terminal_messages: Option<Vec<motosan_agent_loop::Message>> = None;
            let mut terminal_result: Option<motosan_agent_loop::Result<motosan_agent_loop::AgentResult>> = None;

            loop {
                // Forward any progress chunks that arrived in this iteration.
                while let Ok(chunk) = progress_guard.try_recv() {
                    yield UiEvent::ToolCallProgress {
                        id: progress_event_id(&tracker),
                        chunk: ProgressChunk::from(chunk),
                    };
                }

                tokio::select! {
                    biased;
                    maybe_item = agent_stream.next() => {
                        match maybe_item {
                            Some(AgentStreamItem::Event(ev)) => {
                                if let Some(ui) = map_event(ev, &tracker) {
                                    yield ui;
                                }
                            }
                            Some(AgentStreamItem::Terminal(term)) => {
                                terminal_result = Some(term.result);
                                terminal_messages = Some(term.messages);
                                break;
                            }
                            None => break,
                        }
                    }
                    Some(chunk) = progress_guard.recv() => {
                        yield UiEvent::ToolCallProgress {
                            id: progress_event_id(&tracker),
                            chunk: ProgressChunk::from(chunk),
                        };
                    }
                }
            }

            // Tear down the interrupt bridge whether or not cancellation fired.
            interrupt_bridge.abort();

            // Persist new messages via record_turn_outcome (only when terminal reached).
            if let Some(msgs) = terminal_messages.as_ref() {
                if let Err(err) = session.record_turn_outcome(epoch, previous_len, msgs).await {
                    yield UiEvent::Error(format!("session.record_turn_outcome: {err}"));
                }
            }

            // Translate the terminal Result into final UiEvents.
            match terminal_result {
                Some(Ok(_)) => {
                    let final_text = terminal_messages
                        .as_ref()
                        .and_then(|msgs| {
                            msgs.iter()
                                .rev()
                                .find(|m| m.role() == motosan_agent_loop::Role::Assistant)
                                .map(|m| m.text())
                        })
                        .unwrap_or_default();
                    if !final_text.is_empty() {
                        yield UiEvent::AgentMessageComplete(final_text);
                    }
                    // Flush any remaining progress chunks.
                    while let Ok(chunk) = progress_guard.try_recv() {
                        yield UiEvent::ToolCallProgress {
                            id: progress_event_id(&tracker),
                            chunk: ProgressChunk::from(chunk),
                        };
                    }
                    yield UiEvent::AgentTurnComplete;
                }
                Some(Err(err)) => {
                    yield UiEvent::Error(format!("{err}"));
                }
                None => { /* stream closed without terminal — cancelled */ }
            }
        }
    }
}

#[derive(Debug, Default)]
struct ToolCallTracker {
    next_id: usize,
    pending: VecDeque<(String, String)>,
}

impl ToolCallTracker {
    fn start(&mut self, name: &str) -> String {
        self.next_id += 1;
        let id = format!("tool_{}", self.next_id);
        self.pending.push_back((name.to_string(), id.clone()));
        id
    }

    fn complete(&mut self, name: &str) -> String {
        if let Some(pos) = self
            .pending
            .iter()
            .position(|(pending_name, _)| pending_name == name)
        {
            if let Some((_, id)) = self.pending.remove(pos) {
                return id;
            }
        }

        self.next_id += 1;
        format!("tool_{}", self.next_id)
    }

    // ToolProgressChunk does not carry a tool-call id. When exactly one tool is
    // pending we can attribute progress safely; otherwise we must not guess from
    // queue order (for example `pending.back()`), because concurrent tool calls
    // would mislabel output.
    fn progress_id(&self) -> Option<String> {
        match self.pending.len() {
            1 => self.pending.front().map(|(_, id)| id.clone()),
            _ => None,
        }
    }
}

fn lock_tool_tracker(tracker: &Arc<Mutex<ToolCallTracker>>) -> MutexGuard<'_, ToolCallTracker> {
    match tracker.lock() {
        Ok(guard) => guard,
        Err(poisoned) => poisoned.into_inner(),
    }
}

fn progress_event_id(tracker: &Arc<Mutex<ToolCallTracker>>) -> String {
    lock_tool_tracker(tracker)
        .progress_id()
        .unwrap_or_else(|| "tool_unknown".to_string())
}

fn anthropic_api_key_from<F>(auth: &crate::auth::Auth, env_lookup: F) -> Option<String>
where
    F: Fn(&str) -> Option<String>,
{
    env_lookup("ANTHROPIC_API_KEY")
        .map(|key| key.trim().to_string())
        .filter(|key| !key.is_empty())
        .or_else(|| auth.api_key("anthropic").map(str::to_string))
}

fn map_event(ev: AgentEvent, tool_tracker: &Arc<Mutex<ToolCallTracker>>) -> Option<UiEvent> {
    match ev {
        AgentEvent::Core(CoreEvent::TextChunk(delta)) => Some(UiEvent::AgentTextDelta(delta)),
        AgentEvent::Core(CoreEvent::ToolStarted { name }) => {
            let id = lock_tool_tracker(tool_tracker).start(&name);
            Some(UiEvent::ToolCallStarted {
                id,
                name,
                args: serde_json::json!({}),
            })
        }
        AgentEvent::Core(CoreEvent::ToolCompleted { name, result }) => {
            let id = lock_tool_tracker(tool_tracker).complete(&name);
            Some(UiEvent::ToolCallCompleted {
                id,
                result: UiToolResult {
                    is_error: result.is_error,
                    text: format!("{name}: {result:?}"),
                },
            })
        }
        _ => None,
    }
}

type CustomToolsFactory = Box<dyn FnOnce(ToolCtx) -> Vec<Arc<dyn motosan_agent_tool::Tool>>>;

pub struct AppBuilder {
    config: Option<Config>,
    cwd: Option<PathBuf>,
    permission_gate: Option<Arc<dyn PermissionGate>>,
    install_builtin_tools: bool,
    max_iterations: usize,
    llm_override: Option<Arc<dyn LlmClient>>,
    custom_tools_factory: Option<CustomToolsFactory>,
    permissions_policy_path: Option<PathBuf>,
    ui_tx: Option<mpsc::Sender<crate::events::UiEvent>>,
    settings: Option<crate::settings::Settings>,
    auth: Option<crate::auth::Auth>,
    context_discovery_disabled: bool,
    // M3 Phase A:
    session_store: Option<Arc<dyn SessionStore>>,
    resume_session_id: Option<crate::session::SessionId>,
    autocompact_enabled: bool,
    // M4 Phase A:
    skills: Vec<crate::skills::Skill>,
    // M4 Phase B:
    extra_tools: Vec<Arc<dyn motosan_agent_tool::Tool>>,
    mcp_servers: Vec<(String, Arc<dyn motosan_agent_loop::mcp::McpServer>)>,
}

impl Default for AppBuilder {
    fn default() -> Self {
        Self {
            config: None,
            cwd: None,
            permission_gate: None,
            install_builtin_tools: false,
            max_iterations: 20,
            llm_override: None,
            custom_tools_factory: None,
            permissions_policy_path: None,
            ui_tx: None,
            settings: None,
            auth: None,
            context_discovery_disabled: false,
            session_store: None,
            resume_session_id: None,
            autocompact_enabled: false,
            skills: Vec::new(),
            extra_tools: Vec::new(),
            mcp_servers: Vec::new(),
        }
    }
}

impl AppBuilder {
    pub fn new() -> Self {
        Self::default()
    }

    pub fn with_config(mut self, cfg: Config) -> Self {
        self.config = Some(cfg);
        self
    }

    pub fn with_cwd(mut self, cwd: impl Into<PathBuf>) -> Self {
        self.cwd = Some(cwd.into());
        self
    }

    pub fn with_permission_gate(mut self, gate: Arc<dyn PermissionGate>) -> Self {
        self.permission_gate = Some(gate);
        self
    }

    /// Install Capo's builtin tools (`read`, `bash`).
    ///
    /// This is mutually exclusive with `with_custom_tools_factory` /
    /// `build_with_custom_tools`; `build()` returns a configuration error if
    /// both are set.
    pub fn with_builtin_tools(mut self) -> Self {
        self.install_builtin_tools = true;
        self
    }

    pub fn with_max_iterations(mut self, n: usize) -> Self {
        self.max_iterations = n;
        self
    }

    pub fn with_llm(mut self, llm: Arc<dyn LlmClient>) -> Self {
        self.llm_override = Some(llm);
        self
    }

    pub fn with_permissions_config(mut self, path: PathBuf) -> Self {
        self.permissions_policy_path = Some(path);
        self
    }

    pub fn with_ui_channel(mut self, tx: mpsc::Sender<UiEvent>) -> Self {
        self.ui_tx = Some(tx);
        self
    }

    /// M3: install user `Settings`. Replaces `with_config` for new code.
    pub fn with_settings(mut self, settings: crate::settings::Settings) -> Self {
        self.settings = Some(settings);
        self
    }

    /// M3: install `Auth` (credentials for LLM providers).
    pub fn with_auth(mut self, auth: crate::auth::Auth) -> Self {
        self.auth = Some(auth);
        self
    }

    /// M3: disable AGENTS.md / CLAUDE.md discovery for this App.
    /// Opt-out — discovery is on by default in `build()`.
    pub fn disable_context_discovery(mut self) -> Self {
        self.context_discovery_disabled = true;
        self
    }

    /// M3 Phase A: install a `SessionStore` (e.g. `motosan_agent_loop::FileSessionStore`)
    /// for persistence. When omitted, sessions are ephemeral (no jsonl on disk).
    pub fn with_session_store(mut self, store: Arc<dyn SessionStore>) -> Self {
        self.session_store = Some(store);
        self
    }

    /// M3 Phase A: enable autocompact at the `Settings::session.compact_at_context_pct`
    /// threshold. Requires `with_settings` to have been called; otherwise uses
    /// `Settings::default()`. Settings provide `max_context_tokens` and
    /// `keep_turns`. No-op when `settings.session.compact_at_context_pct == 0.0`.
    pub fn with_autocompact(mut self) -> Self {
        self.autocompact_enabled = true;
        self
    }

    /// M4 Phase A: register skills. Pass an empty Vec (or omit the call,
    /// or call `without_skills()`) to disable skill injection. Skills are
    /// rendered into the system prompt's `<available_skills>` block when
    /// the `read` tool is available, and matched against `/skill:<name>`
    /// expansion before user messages reach the LLM.
    pub fn with_skills(mut self, skills: Vec<crate::skills::Skill>) -> Self {
        self.skills = skills;
        self
    }

    pub fn without_skills(mut self) -> Self {
        self.skills.clear();
        self
    }

    /// M4 Phase B: register additional tools (typically MCP). Unlike
    /// `with_custom_tools_factory`, this APPENDS to the builtin tools
    /// and does NOT replace them.
    pub fn with_extra_tools(mut self, tools: Vec<Arc<dyn motosan_agent_tool::Tool>>) -> Self {
        self.extra_tools = tools;
        self
    }

    /// M4 Phase B: register MCP server handles so `App::disconnect_mcp`
    /// can iterate them on shutdown. Storage only — does not connect.
    pub fn with_mcp_servers(
        mut self,
        servers: Vec<(String, Arc<dyn motosan_agent_loop::mcp::McpServer>)>,
    ) -> Self {
        self.mcp_servers = servers;
        self
    }

    /// Install a custom tool set for this app.
    ///
    /// This is mutually exclusive with `with_builtin_tools`; `build()` returns
    /// a configuration error if both are set.
    pub fn with_custom_tools_factory(
        mut self,
        factory: impl FnOnce(ToolCtx) -> Vec<Arc<dyn motosan_agent_tool::Tool>> + 'static,
    ) -> Self {
        self.custom_tools_factory = Some(Box::new(factory));
        self
    }

    /// Convenience wrapper for `with_custom_tools_factory(...).build()`.
    ///
    /// This is mutually exclusive with `with_builtin_tools`.
    pub async fn build_with_custom_tools(
        self,
        factory: impl FnOnce(ToolCtx) -> Vec<Arc<dyn motosan_agent_tool::Tool>> + 'static,
    ) -> Result<App> {
        self.with_custom_tools_factory(factory).build().await
    }

    /// M3 Phase A: build the App with an optional resume session id.
    ///
    /// - `Some(id)` + `session_store: Some(_)` → `AgentSession::resume(id, store, engine, llm)`,
    ///   then replay history into `ToolCtx.read_files`.
    /// - `Some(id)` + `session_store: None` → error (resume requires a store).
    /// - `None` + `session_store: Some(_)` → `AgentSession::new_with_store(fresh_id, store, engine, llm)`.
    /// - `None` + `session_store: None` → `AgentSession::new(engine, llm)` (ephemeral).
    pub async fn build_with_session(
        mut self,
        resume: Option<crate::session::SessionId>,
    ) -> Result<App> {
        if let Some(id) = resume {
            if self.session_store.is_none() {
                return Err(AppError::Config(
                    "build_with_session(Some(id)) requires with_session_store(...)".into(),
                ));
            }
            self.resume_session_id = Some(id);
        }
        self.build_internal().await
    }

    /// Legacy entry point; equivalent to `build_with_session(None)`.
    pub async fn build(self) -> Result<App> {
        self.build_with_session(None).await
    }

    async fn build_internal(mut self) -> Result<App> {
        let mcp_servers = std::mem::take(&mut self.mcp_servers);
        let extra_tools = std::mem::take(&mut self.extra_tools);
        let skills = self.skills.clone();
        if self.install_builtin_tools && self.custom_tools_factory.is_some() {
            return Err(AppError::Config(
                "with_builtin_tools and with_custom_tools_factory are mutually exclusive".into(),
            ));
        }

        // Synthesise the legacy `Config` so the rest of `build()` keeps
        // working without a wholesale rewrite. Settings + Auth override the
        // deprecated `Config` when both APIs are supplied.
        let has_config = self.config.is_some();
        let has_auth = self.auth.is_some();
        let mut config = self.config.unwrap_or_default();
        let settings = match self.settings {
            Some(settings) => settings,
            None => {
                let mut settings = crate::settings::Settings::default();
                settings.model.provider = config.model.provider.clone();
                settings.model.name = config.model.name.clone();
                settings.model.max_tokens = config.model.max_tokens;
                settings
            }
        };
        config.model.provider = settings.model.provider.clone();
        config.model.name = settings.model.name.clone();
        config.model.max_tokens = settings.model.max_tokens;
        let mut auth = self.auth.unwrap_or_default();
        if !has_auth {
            if let Some(key) = config.anthropic.api_key.as_deref() {
                auth.0.insert(
                    "anthropic".into(),
                    crate::auth::ProviderAuth::ApiKey {
                        key: key.to_string(),
                    },
                );
            }
        }
        let env_or_auth_key = anthropic_api_key_from(&auth, |name| std::env::var(name).ok());
        if env_or_auth_key.is_some() || has_auth || !has_config {
            config.anthropic.api_key = env_or_auth_key;
        }
        let cwd = self
            .cwd
            .or_else(|| std::env::current_dir().ok())
            .unwrap_or_else(|| PathBuf::from("."));
        let permission_gate = self.permission_gate.unwrap_or_else(|| {
            // When no gate is provided *and* no ui channel is wired,
            // fall back to NoOp with a warning log; when ui channel IS
            // wired, the PermissionExtension handles the real decisions.
            if self.ui_tx.is_some() {
                Arc::new(NoOpPermissionGate) as Arc<dyn PermissionGate>
            } else {
                tracing::warn!("no PermissionGate and no UI channel — tools run unchecked");
                Arc::new(NoOpPermissionGate) as Arc<dyn PermissionGate>
            }
        });

        let llm = if let Some(llm) = self.llm_override {
            llm
        } else {
            build_llm_client(&settings, &auth)?
        };

        // Shared progress channel consumed by `send_user_message`.
        let (progress_tx, progress_rx) = mpsc::channel::<ToolProgressChunk>(64);
        let tool_ctx = ToolCtx::new(&cwd, Arc::clone(&permission_gate), progress_tx);
        let cancel_token = tool_ctx.cancel_token.clone();

        let mut tools = if self.install_builtin_tools {
            builtin_tools(tool_ctx.clone())
        } else if let Some(factory) = self.custom_tools_factory {
            factory(tool_ctx.clone())
        } else {
            Vec::new()
        };
        tools.extend(extra_tools);

        let tool_names: Vec<String> = tools.iter().map(|t| t.def().name).collect();
        let base_prompt = build_system_prompt(&tool_names, &skills);
        let system_prompt = if self.context_discovery_disabled {
            base_prompt
        } else {
            let agent_dir = crate::paths::agent_dir();
            let context = crate::context_files::load_project_context_files(&cwd, &agent_dir);
            crate::context_files::assemble_system_prompt(&base_prompt, &context, &cwd)
        };
        let motosan_tool_context = ToolContext::new("capo", "capo").with_cwd(&cwd);

        // Permissions.
        let policy: Arc<crate::permissions::Policy> =
            Arc::new(match self.permissions_policy_path.as_ref() {
                Some(path) => crate::permissions::Policy::load_or_default(path)?,
                None => crate::permissions::Policy::default(),
            });
        let session_cache = Arc::new(crate::permissions::SessionCache::new());

        let mut engine_builder = Engine::builder()
            .max_iterations(self.max_iterations)
            .system_prompt(system_prompt)
            .tool_context(motosan_tool_context);
        for tool in tools {
            engine_builder = engine_builder.tool(tool);
        }
        if let Some(ui_tx) = self.ui_tx {
            let ext = crate::permissions::PermissionExtension::new(
                Arc::clone(&policy),
                Arc::clone(&session_cache),
                cwd.clone(),
                ui_tx,
            );
            engine_builder = engine_builder.extension(Box::new(ext));
        }
        // M3 Phase A: autocompact extension.
        if self.autocompact_enabled
            && settings.session.compact_at_context_pct > 0.0
            && settings.session.compact_at_context_pct < 1.0
        {
            let cfg = AutocompactConfig {
                threshold: settings.session.compact_at_context_pct,
                max_context_tokens: settings.session.max_context_tokens,
                keep_turns: settings.session.keep_turns.max(1),
            };
            let ext = AutocompactExtension::new(cfg, Arc::clone(&llm));
            engine_builder = engine_builder.extension(Box::new(ext));
        }
        let engine = engine_builder.build();

        // M3 Phase A: AgentSession construction.
        let session = match (self.resume_session_id, self.session_store) {
            (Some(id), Some(store)) => {
                let s =
                    AgentSession::resume(id.as_str(), Arc::clone(&store), engine, Arc::clone(&llm))
                        .await
                        .map_err(|err| AppError::Config(format!("resume failed: {err}")))?;
                // Replay-hydrate `ToolCtx.read_files` from the loaded history.
                let entries = s
                    .entries()
                    .await
                    .map_err(|err| AppError::Config(format!("entries failed: {err}")))?;
                crate::session::hydrate_read_files(&entries, &tool_ctx).await?;
                s
            }
            (None, Some(store)) => {
                let id = crate::session::SessionId::new();
                AgentSession::new_with_store(id.into_string(), store, engine, Arc::clone(&llm))
            }
            (None, None) => AgentSession::new(engine, Arc::clone(&llm)),
            (Some(_), None) => unreachable!("guarded in build_with_session"),
        };

        Ok(App {
            session: Arc::new(session),
            config,
            cancel_token,
            progress_rx: Arc::new(tokio::sync::Mutex::new(progress_rx)),
            next_tool_id: Arc::new(Mutex::new(ToolCallTracker::default())),
            skills: Arc::new(skills),
            mcp_servers,
            session_cache,
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::config::{AnthropicConfig, ModelConfig};
    use crate::events::UiEvent;
    use async_trait::async_trait;
    use motosan_agent_loop::{ChatOutput, LlmClient, LlmResponse, Message, ToolCallItem};
    use motosan_agent_tool::ToolDef;
    use std::sync::atomic::{AtomicUsize, Ordering};

    #[tokio::test]
    async fn builder_fails_without_api_key() {
        let cfg = Config {
            anthropic: AnthropicConfig {
                api_key: None,
                base_url: "https://api.anthropic.com".into(),
            },
            model: ModelConfig {
                provider: "anthropic".into(),
                name: "claude-sonnet-4-6".into(),
                max_tokens: 4096,
            },
        };
        let err = match AppBuilder::new()
            .with_config(cfg)
            .with_builtin_tools()
            .build()
            .await
        {
            Ok(_) => panic!("must fail without key"),
            Err(err) => err,
        };
        assert!(format!("{err}").contains("ANTHROPIC_API_KEY"));
    }

    struct ToolOnlyLlm {
        turn: AtomicUsize,
    }

    #[async_trait]
    impl LlmClient for ToolOnlyLlm {
        async fn chat(
            &self,
            _messages: &[Message],
            _tools: &[ToolDef],
        ) -> motosan_agent_loop::Result<ChatOutput> {
            let turn = self.turn.fetch_add(1, Ordering::SeqCst);
            if turn == 0 {
                Ok(ChatOutput::new(LlmResponse::ToolCalls(vec![
                    ToolCallItem {
                        id: "t1".into(),
                        name: "read".into(),
                        args: serde_json::json!({"path":"nope.txt"}),
                    },
                ])))
            } else {
                Ok(ChatOutput::new(LlmResponse::Message(String::new())))
            }
        }
    }

    #[tokio::test]
    async fn empty_final_message_is_not_emitted() {
        let dir = tempfile::tempdir().unwrap();
        let mut cfg = Config::default();
        cfg.anthropic.api_key = Some("sk-unused".into());
        let app = AppBuilder::new()
            .with_config(cfg)
            .with_cwd(dir.path())
            .with_builtin_tools()
            .with_llm(std::sync::Arc::new(ToolOnlyLlm {
                turn: AtomicUsize::new(0),
            }))
            .build()
            .await
            .expect("build");
        let events: Vec<UiEvent> =
            futures::StreamExt::collect(app.send_user_message("x".into())).await;
        let empties = events
            .iter()
            .filter(|e| matches!(e, UiEvent::AgentMessageComplete(t) if t.is_empty()))
            .count();
        assert_eq!(
            empties, 0,
            "should not emit empty final message, got: {events:?}"
        );
    }

    struct EchoLlm;

    #[async_trait]
    impl LlmClient for EchoLlm {
        async fn chat(
            &self,
            _messages: &[Message],
            _tools: &[ToolDef],
        ) -> motosan_agent_loop::Result<ChatOutput> {
            Ok(ChatOutput::new(LlmResponse::Message("ok".into())))
        }
    }

    #[test]
    fn anthropic_env_api_key_overrides_auth_json_key() {
        let mut auth = crate::auth::Auth::default();
        auth.0.insert(
            "anthropic".into(),
            crate::auth::ProviderAuth::ApiKey {
                key: "sk-auth".into(),
            },
        );

        let key = anthropic_api_key_from(&auth, |name| {
            (name == "ANTHROPIC_API_KEY").then(|| " sk-env ".to_string())
        });
        assert_eq!(key.as_deref(), Some("sk-env"));
    }

    #[tokio::test]
    async fn with_settings_overrides_deprecated_config_model() {
        use crate::settings::Settings;

        let mut config = Config::default();
        config.model.name = "from-config".into();
        config.anthropic.api_key = Some("sk-config".into());

        let mut settings = Settings::default();
        settings.model.name = "from-settings".into();

        let tmp = tempfile::tempdir().unwrap();
        let app = AppBuilder::new()
            .with_config(config)
            .with_settings(settings)
            .with_cwd(tmp.path())
            .disable_context_discovery()
            .with_llm(Arc::new(EchoLlm))
            .build()
            .await
            .expect("build");
        assert_eq!(app.config().model.name, "from-settings");
        assert_eq!(app.config().anthropic.api_key.as_deref(), Some("sk-config"));
    }

    #[tokio::test]
    async fn with_settings_synthesises_legacy_config_for_build() {
        use crate::auth::{Auth, ProviderAuth};
        use crate::settings::Settings;

        let mut settings = Settings::default();
        settings.model.name = "claude-sonnet-4-6".into();

        let mut auth = Auth::default();
        auth.0.insert(
            "anthropic".into(),
            ProviderAuth::ApiKey {
                key: "sk-test".into(),
            },
        );

        let tmp = tempfile::tempdir().unwrap();
        let app = AppBuilder::new()
            .with_settings(settings)
            .with_auth(auth)
            .with_cwd(tmp.path())
            .with_builtin_tools()
            .disable_context_discovery()
            .with_llm(Arc::new(EchoLlm))
            .build()
            .await
            .expect("build");
        let _ = app;
    }

    #[tokio::test]
    async fn cancel_before_turn_does_not_poison_future_turns() {
        let dir = tempfile::tempdir().unwrap();
        let mut cfg = Config::default();
        cfg.anthropic.api_key = Some("sk-unused".into());
        let app = AppBuilder::new()
            .with_config(cfg)
            .with_cwd(dir.path())
            .with_builtin_tools()
            .with_llm(std::sync::Arc::new(EchoLlm))
            .build()
            .await
            .expect("build");

        app.cancel();
        let events: Vec<UiEvent> = app.send_user_message("x".into()).collect().await;

        assert!(
            events
                .iter()
                .any(|e| matches!(e, UiEvent::AgentMessageComplete(text) if text == "ok")),
            "turn should use a fresh cancellation token: {events:?}"
        );
    }

    #[test]
    fn map_event_matches_started_and_completed_ids_by_tool_name() {
        let tracker = Arc::new(Mutex::new(ToolCallTracker::default()));

        let started_bash = map_event(
            AgentEvent::Core(CoreEvent::ToolStarted {
                name: "bash".into(),
            }),
            &tracker,
        );
        let started_read = map_event(
            AgentEvent::Core(CoreEvent::ToolStarted {
                name: "read".into(),
            }),
            &tracker,
        );
        let completed_bash = map_event(
            AgentEvent::Core(CoreEvent::ToolCompleted {
                name: "bash".into(),
                result: motosan_agent_tool::ToolResult::text("ok"),
            }),
            &tracker,
        );
        let completed_read = map_event(
            AgentEvent::Core(CoreEvent::ToolCompleted {
                name: "read".into(),
                result: motosan_agent_tool::ToolResult::text("ok"),
            }),
            &tracker,
        );

        assert!(matches!(
            started_bash,
            Some(UiEvent::ToolCallStarted { ref id, ref name, .. }) if id == "tool_1" && name == "bash"
        ));
        assert!(matches!(
            started_read,
            Some(UiEvent::ToolCallStarted { ref id, ref name, .. }) if id == "tool_2" && name == "read"
        ));
        assert!(matches!(
            completed_bash,
            Some(UiEvent::ToolCallCompleted { ref id, .. }) if id == "tool_1"
        ));
        assert!(matches!(
            completed_read,
            Some(UiEvent::ToolCallCompleted { ref id, .. }) if id == "tool_2"
        ));
    }

    #[test]
    fn tool_tracker_handles_two_concurrent_invocations_of_same_tool() {
        let tracker = Arc::new(Mutex::new(ToolCallTracker::default()));
        let s1 = map_event(
            AgentEvent::Core(CoreEvent::ToolStarted {
                name: "bash".into(),
            }),
            &tracker,
        );
        let s2 = map_event(
            AgentEvent::Core(CoreEvent::ToolStarted {
                name: "bash".into(),
            }),
            &tracker,
        );
        let c1 = map_event(
            AgentEvent::Core(CoreEvent::ToolCompleted {
                name: "bash".into(),
                result: motosan_agent_tool::ToolResult::text("a"),
            }),
            &tracker,
        );
        let c2 = map_event(
            AgentEvent::Core(CoreEvent::ToolCompleted {
                name: "bash".into(),
                result: motosan_agent_tool::ToolResult::text("b"),
            }),
            &tracker,
        );

        let id_s1 = match s1 {
            Some(UiEvent::ToolCallStarted { id, .. }) => id,
            other => panic!("{other:?}"),
        };
        let id_s2 = match s2 {
            Some(UiEvent::ToolCallStarted { id, .. }) => id,
            other => panic!("{other:?}"),
        };
        let id_c1 = match c1 {
            Some(UiEvent::ToolCallCompleted { id, .. }) => id,
            other => panic!("{other:?}"),
        };
        let id_c2 = match c2 {
            Some(UiEvent::ToolCallCompleted { id, .. }) => id,
            other => panic!("{other:?}"),
        };

        assert_eq!(id_s1, id_c1);
        assert_eq!(id_s2, id_c2);
        assert_ne!(id_s1, id_s2);
    }

    #[tokio::test]
    async fn concurrent_send_user_message_returns_an_error_instead_of_hanging() {
        let dir = tempfile::tempdir().unwrap();
        let mut cfg = Config::default();
        cfg.anthropic.api_key = Some("sk-unused".into());
        let app = AppBuilder::new()
            .with_config(cfg)
            .with_cwd(dir.path())
            .with_builtin_tools()
            .with_llm(std::sync::Arc::new(ToolOnlyLlm {
                turn: AtomicUsize::new(0),
            }))
            .build()
            .await
            .expect("build");

        let mut first = Box::pin(app.send_user_message("first".into()));
        let first_event = first.next().await;
        assert!(matches!(first_event, Some(UiEvent::AgentTurnStarted)));

        let second_events: Vec<UiEvent> = app.send_user_message("second".into()).collect().await;
        assert_eq!(
            second_events.len(),
            1,
            "expected immediate single error event, got: {second_events:?}"
        );
        assert!(matches!(
            &second_events[0],
            UiEvent::Error(msg) if msg.contains("single-turn-per-App")
        ));
    }

    #[test]
    fn progress_events_only_claim_an_id_when_exactly_one_tool_is_pending() {
        let tracker = Arc::new(Mutex::new(ToolCallTracker::default()));
        assert_eq!(progress_event_id(&tracker), "tool_unknown");

        let only = map_event(
            AgentEvent::Core(CoreEvent::ToolStarted {
                name: "bash".into(),
            }),
            &tracker,
        );
        let only_id = match only {
            Some(UiEvent::ToolCallStarted { id, .. }) => id,
            other => panic!("{other:?}"),
        };
        assert_eq!(progress_event_id(&tracker), only_id);

        let _second = map_event(
            AgentEvent::Core(CoreEvent::ToolStarted {
                name: "read".into(),
            }),
            &tracker,
        );
        assert_eq!(progress_event_id(&tracker), "tool_unknown");
    }

    #[tokio::test]
    async fn builder_rejects_builtin_and_custom_tools_together() {
        let mut cfg = Config::default();
        cfg.anthropic.api_key = Some("sk-unused".into());
        let dir = tempfile::tempdir().unwrap();
        let err = match AppBuilder::new()
            .with_config(cfg)
            .with_cwd(dir.path())
            .with_builtin_tools()
            .with_custom_tools_factory(|_| Vec::new())
            .build()
            .await
        {
            Ok(_) => panic!("must reject conflicting tool configuration"),
            Err(err) => err,
        };

        assert!(format!("{err}").contains("mutually exclusive"));
    }

    /// M3 Phase A smoke: two turns share history when a SessionStore is wired.
    #[tokio::test]
    async fn two_turns_in_same_session_share_history() {
        #[derive(Default)]
        struct CounterLlm {
            turn: AtomicUsize,
        }
        #[async_trait]
        impl LlmClient for CounterLlm {
            async fn chat(
                &self,
                messages: &[Message],
                _tools: &[ToolDef],
            ) -> motosan_agent_loop::Result<ChatOutput> {
                let turn = self.turn.fetch_add(1, Ordering::SeqCst);
                let answer = format!("turn-{turn}-saw-{}-messages", messages.len());
                Ok(ChatOutput::new(LlmResponse::Message(answer)))
            }
        }

        let tmp = tempfile::tempdir().unwrap();
        let store = std::sync::Arc::new(motosan_agent_loop::FileSessionStore::new(
            tmp.path().to_path_buf(),
        ));

        let app = AppBuilder::new()
            .with_settings(crate::settings::Settings::default())
            .with_auth(crate::auth::Auth::default())
            .with_cwd(tmp.path())
            .with_builtin_tools()
            .disable_context_discovery()
            .with_llm(std::sync::Arc::new(CounterLlm::default()))
            .with_session_store(store)
            .build_with_session(None)
            .await
            .expect("build");

        let _events1: Vec<UiEvent> = app.send_user_message("hi".into()).collect().await;
        let events2: Vec<UiEvent> = app.send_user_message("again".into()).collect().await;

        // Turn 2's LLM saw turn 1's user message + turn 1's assistant + turn 2's new user.
        let saw_more_than_one = events2.iter().any(|e| {
            matches!(
                e,
                UiEvent::AgentMessageComplete(t) if t.contains("messages") && !t.contains("saw-1-")
            )
        });
        assert!(
            saw_more_than_one,
            "second turn should have seen history; events: {events2:?}"
        );
    }
}

#[cfg(test)]
mod skills_builder_tests {
    use super::*;
    use crate::skills::types::{Skill, SkillSource};
    use std::path::PathBuf;

    fn fixture() -> Skill {
        Skill {
            name: "x".into(),
            description: "d".into(),
            file_path: PathBuf::from("/x.md"),
            base_dir: PathBuf::from("/"),
            disable_model_invocation: false,
            source: SkillSource::Global,
        }
    }

    #[test]
    fn with_skills_stores_skills() {
        let b = AppBuilder::new().with_skills(vec![fixture()]);
        assert_eq!(b.skills.len(), 1);
        assert_eq!(b.skills[0].name, "x");
    }

    #[test]
    fn without_skills_clears() {
        let b = AppBuilder::new()
            .with_skills(vec![fixture()])
            .without_skills();
        assert!(b.skills.is_empty());
    }
}

#[cfg(test)]
mod mcp_builder_tests {
    use super::*;
    use motosan_agent_tool::Tool;

    // Trivial fake Tool just to verify with_extra_tools stores Arcs.
    struct FakeTool;
    impl Tool for FakeTool {
        fn def(&self) -> motosan_agent_tool::ToolDef {
            motosan_agent_tool::ToolDef {
                name: "fake__echo".into(),
                description: "test".into(),
                input_schema: serde_json::json!({"type": "object"}),
            }
        }
        fn call(
            &self,
            _args: serde_json::Value,
            _ctx: &motosan_agent_tool::ToolContext,
        ) -> std::pin::Pin<
            Box<dyn std::future::Future<Output = motosan_agent_tool::ToolResult> + Send + '_>,
        > {
            Box::pin(async { motosan_agent_tool::ToolResult::text("ok") })
        }
    }

    #[test]
    fn with_extra_tools_stores_tools() {
        let tools: Vec<Arc<dyn Tool>> = vec![Arc::new(FakeTool)];
        let b = AppBuilder::new().with_extra_tools(tools);
        assert_eq!(b.extra_tools.len(), 1);
    }
}