tandem_core/

engine_loop.rs

use chrono::Utc;
use futures::future::BoxFuture;
use futures::StreamExt;
use serde_json::{json, Map, Number, Value};
use std::collections::{hash_map::DefaultHasher, HashMap, HashSet};
use std::hash::{Hash, Hasher};
use std::path::{Path, PathBuf};
use tandem_observability::{emit_event, ObservabilityEvent, ProcessKind};
use tandem_providers::{ChatMessage, ProviderRegistry, StreamChunk, TokenUsage};
use tandem_tools::{validate_tool_schemas, ToolRegistry};
use tandem_types::{
    EngineEvent, HostOs, HostRuntimeContext, Message, MessagePart, MessagePartInput, MessageRole,
    ModelSpec, PathStyle, SendMessageRequest, ShellFamily,
};
use tandem_wire::WireMessagePart;
use tokio_util::sync::CancellationToken;
use tracing::Level;

use crate::{
    derive_session_title_from_prompt, title_needs_repair, AgentDefinition, AgentRegistry,
    CancellationRegistry, EventBus, PermissionAction, PermissionManager, PluginRegistry, Storage,
};
use tokio::sync::RwLock;

#[derive(Default)]
struct StreamedToolCall {
    name: String,
    args: String,
}

#[derive(Debug, Clone)]
pub struct SpawnAgentToolContext {
    pub session_id: String,
    pub message_id: String,
    pub tool_call_id: Option<String>,
    pub args: Value,
}

#[derive(Debug, Clone)]
pub struct SpawnAgentToolResult {
    pub output: String,
    pub metadata: Value,
}

#[derive(Debug, Clone)]
pub struct ToolPolicyContext {
    pub session_id: String,
    pub message_id: String,
    pub tool: String,
    pub args: Value,
}

#[derive(Debug, Clone)]
pub struct ToolPolicyDecision {
    pub allowed: bool,
    pub reason: Option<String>,
}

pub trait SpawnAgentHook: Send + Sync {
    fn spawn_agent(
        &self,
        ctx: SpawnAgentToolContext,
    ) -> BoxFuture<'static, anyhow::Result<SpawnAgentToolResult>>;
}

pub trait ToolPolicyHook: Send + Sync {
    fn evaluate_tool(
        &self,
        ctx: ToolPolicyContext,
    ) -> BoxFuture<'static, anyhow::Result<ToolPolicyDecision>>;
}

#[derive(Clone)]
pub struct EngineLoop {
    storage: std::sync::Arc<Storage>,
    event_bus: EventBus,
    providers: ProviderRegistry,
    plugins: PluginRegistry,
    agents: AgentRegistry,
    permissions: PermissionManager,
    tools: ToolRegistry,
    cancellations: CancellationRegistry,
    host_runtime_context: HostRuntimeContext,
    workspace_overrides: std::sync::Arc<RwLock<HashMap<String, u64>>>,
    session_allowed_tools: std::sync::Arc<RwLock<HashMap<String, Vec<String>>>>,
    spawn_agent_hook: std::sync::Arc<RwLock<Option<std::sync::Arc<dyn SpawnAgentHook>>>>,
    tool_policy_hook: std::sync::Arc<RwLock<Option<std::sync::Arc<dyn ToolPolicyHook>>>>,
}

impl EngineLoop {
    #[allow(clippy::too_many_arguments)]
    pub fn new(
        storage: std::sync::Arc<Storage>,
        event_bus: EventBus,
        providers: ProviderRegistry,
        plugins: PluginRegistry,
        agents: AgentRegistry,
        permissions: PermissionManager,
        tools: ToolRegistry,
        cancellations: CancellationRegistry,
        host_runtime_context: HostRuntimeContext,
    ) -> Self {
        Self {
            storage,
            event_bus,
            providers,
            plugins,
            agents,
            permissions,
            tools,
            cancellations,
            host_runtime_context,
            workspace_overrides: std::sync::Arc::new(RwLock::new(HashMap::new())),
            session_allowed_tools: std::sync::Arc::new(RwLock::new(HashMap::new())),
            spawn_agent_hook: std::sync::Arc::new(RwLock::new(None)),
            tool_policy_hook: std::sync::Arc::new(RwLock::new(None)),
        }
    }

    pub async fn set_spawn_agent_hook(&self, hook: std::sync::Arc<dyn SpawnAgentHook>) {
        *self.spawn_agent_hook.write().await = Some(hook);
    }

    pub async fn set_tool_policy_hook(&self, hook: std::sync::Arc<dyn ToolPolicyHook>) {
        *self.tool_policy_hook.write().await = Some(hook);
    }

    pub async fn set_session_allowed_tools(&self, session_id: &str, allowed_tools: Vec<String>) {
        let normalized = allowed_tools
            .into_iter()
            .map(|tool| normalize_tool_name(&tool))
            .filter(|tool| !tool.trim().is_empty())
            .collect::<Vec<_>>();
        self.session_allowed_tools
            .write()
            .await
            .insert(session_id.to_string(), normalized);
    }

    pub async fn clear_session_allowed_tools(&self, session_id: &str) {
        self.session_allowed_tools.write().await.remove(session_id);
    }

    pub async fn grant_workspace_override_for_session(
        &self,
        session_id: &str,
        ttl_seconds: u64,
    ) -> u64 {
        let expires_at = chrono::Utc::now()
            .timestamp_millis()
            .max(0)
            .saturating_add((ttl_seconds as i64).saturating_mul(1000))
            as u64;
        self.workspace_overrides
            .write()
            .await
            .insert(session_id.to_string(), expires_at);
        expires_at
    }

    pub async fn run_prompt_async(
        &self,
        session_id: String,
        req: SendMessageRequest,
    ) -> anyhow::Result<()> {
        self.run_prompt_async_with_context(session_id, req, None)
            .await
    }

    pub async fn run_prompt_async_with_context(
        &self,
        session_id: String,
        req: SendMessageRequest,
        correlation_id: Option<String>,
    ) -> anyhow::Result<()> {
        let session_model = self
            .storage
            .get_session(&session_id)
            .await
            .and_then(|s| s.model);
        let (provider_id, model_id_value) =
            resolve_model_route(req.model.as_ref(), session_model.as_ref()).ok_or_else(|| {
                anyhow::anyhow!(
                "MODEL_SELECTION_REQUIRED: explicit provider/model is required for this request."
            )
            })?;
        let correlation_ref = correlation_id.as_deref();
        let model_id = Some(model_id_value.as_str());
        let cancel = self.cancellations.create(&session_id).await;
        emit_event(
            Level::INFO,
            ProcessKind::Engine,
            ObservabilityEvent {
                event: "provider.call.start",
                component: "engine.loop",
                correlation_id: correlation_ref,
                session_id: Some(&session_id),
                run_id: None,
                message_id: None,
                provider_id: Some(provider_id.as_str()),
                model_id,
                status: Some("start"),
                error_code: None,
                detail: Some("run_prompt_async dispatch"),
            },
        );
        self.event_bus.publish(EngineEvent::new(
            "session.status",
            json!({"sessionID": session_id, "status":"running"}),
        ));
        let text = req
            .parts
            .iter()
            .map(|p| match p {
                MessagePartInput::Text { text } => text.clone(),
                MessagePartInput::File {
                    mime,
                    filename,
                    url,
                } => format!(
                    "[file mime={} name={} url={}]",
                    mime,
                    filename.clone().unwrap_or_else(|| "unknown".to_string()),
                    url
                ),
            })
            .collect::<Vec<_>>()
            .join("\n");
        self.auto_rename_session_from_user_text(&session_id, &text)
            .await;
        let active_agent = self.agents.get(req.agent.as_deref()).await;
        let mut user_message_id = self
            .find_recent_matching_user_message_id(&session_id, &text)
            .await;
        if user_message_id.is_none() {
            let user_message = Message::new(
                MessageRole::User,
                vec![MessagePart::Text { text: text.clone() }],
            );
            let created_message_id = user_message.id.clone();
            self.storage
                .append_message(&session_id, user_message)
                .await?;

            let user_part = WireMessagePart::text(&session_id, &created_message_id, text.clone());
            self.event_bus.publish(EngineEvent::new(
                "message.part.updated",
                json!({
                    "part": user_part,
                    "delta": text,
                    "agent": active_agent.name
                }),
            ));
            user_message_id = Some(created_message_id);
        }
        let user_message_id = user_message_id.unwrap_or_else(|| "unknown".to_string());

        if cancel.is_cancelled() {
            self.event_bus.publish(EngineEvent::new(
                "session.status",
                json!({"sessionID": session_id, "status":"cancelled"}),
            ));
            self.cancellations.remove(&session_id).await;
            return Ok(());
        }

        let mut question_tool_used = false;
        let completion = if let Some((tool, args)) = parse_tool_invocation(&text) {
            if normalize_tool_name(&tool) == "question" {
                question_tool_used = true;
            }
            if !agent_can_use_tool(&active_agent, &tool) {
                format!(
                    "Tool `{tool}` is not enabled for agent `{}`.",
                    active_agent.name
                )
            } else {
                self.execute_tool_with_permission(
                    &session_id,
                    &user_message_id,
                    tool.clone(),
                    args,
                    active_agent.skills.as_deref(),
                    &text,
                    None,
                    cancel.clone(),
                )
                .await?
                .unwrap_or_default()
            }
        } else {
            let mut completion = String::new();
            let mut max_iterations = 25usize;
            let mut followup_context: Option<String> = None;
            let mut last_tool_outputs: Vec<String> = Vec::new();
            let mut tool_call_counts: HashMap<String, usize> = HashMap::new();
            let mut readonly_tool_cache: HashMap<String, String> = HashMap::new();
            let mut readonly_signature_counts: HashMap<String, usize> = HashMap::new();
            let mut shell_mismatch_signatures: HashSet<String> = HashSet::new();
            let mut websearch_query_blocked = false;
            let mut auto_workspace_probe_attempted = false;

            while max_iterations > 0 && !cancel.is_cancelled() {
                max_iterations -= 1;
                let mut messages = load_chat_history(self.storage.clone(), &session_id).await;
                let mut system_parts =
                    vec![tandem_runtime_system_prompt(&self.host_runtime_context)];
                if let Some(system) = active_agent.system_prompt.as_ref() {
                    system_parts.push(system.clone());
                }
                messages.insert(
                    0,
                    ChatMessage {
                        role: "system".to_string(),
                        content: system_parts.join("\n\n"),
                    },
                );
                if let Some(extra) = followup_context.take() {
                    messages.push(ChatMessage {
                        role: "user".to_string(),
                        content: extra,
                    });
                }
                let mut tool_schemas = self.tools.list().await;
                if active_agent.tools.is_some() {
                    tool_schemas.retain(|schema| agent_can_use_tool(&active_agent, &schema.name));
                }
                if let Some(allowed_tools) = self
                    .session_allowed_tools
                    .read()
                    .await
                    .get(&session_id)
                    .cloned()
                {
                    if !allowed_tools.is_empty() {
                        tool_schemas.retain(|schema| {
                            let normalized = normalize_tool_name(&schema.name);
                            allowed_tools.iter().any(|tool| tool == &normalized)
                        });
                    }
                }
                if let Err(validation_err) = validate_tool_schemas(&tool_schemas) {
                    let detail = validation_err.to_string();
                    emit_event(
                        Level::ERROR,
                        ProcessKind::Engine,
                        ObservabilityEvent {
                            event: "provider.call.error",
                            component: "engine.loop",
                            correlation_id: correlation_ref,
                            session_id: Some(&session_id),
                            run_id: None,
                            message_id: Some(&user_message_id),
                            provider_id: Some(provider_id.as_str()),
                            model_id,
                            status: Some("failed"),
                            error_code: Some("TOOL_SCHEMA_INVALID"),
                            detail: Some(&detail),
                        },
                    );
                    anyhow::bail!("{detail}");
                }
                let stream = self
                    .providers
                    .stream_for_provider(
                        Some(provider_id.as_str()),
                        Some(model_id_value.as_str()),
                        messages,
                        Some(tool_schemas),
                        cancel.clone(),
                    )
                    .await
                    .inspect_err(|err| {
                        let error_text = err.to_string();
                        let error_code = provider_error_code(&error_text);
                        let detail = truncate_text(&error_text, 500);
                        emit_event(
                            Level::ERROR,
                            ProcessKind::Engine,
                            ObservabilityEvent {
                                event: "provider.call.error",
                                component: "engine.loop",
                                correlation_id: correlation_ref,
                                session_id: Some(&session_id),
                                run_id: None,
                                message_id: Some(&user_message_id),
                                provider_id: Some(provider_id.as_str()),
                                model_id,
                                status: Some("failed"),
                                error_code: Some(error_code),
                                detail: Some(&detail),
                            },
                        );
                    })?;
                tokio::pin!(stream);
                completion.clear();
                let mut streamed_tool_calls: HashMap<String, StreamedToolCall> = HashMap::new();
                let mut provider_usage: Option<TokenUsage> = None;
                while let Some(chunk) = stream.next().await {
                    let chunk = match chunk {
                        Ok(chunk) => chunk,
                        Err(err) => {
                            let error_text = err.to_string();
                            let error_code = provider_error_code(&error_text);
                            let detail = truncate_text(&error_text, 500);
                            emit_event(
                                Level::ERROR,
                                ProcessKind::Engine,
                                ObservabilityEvent {
                                    event: "provider.call.error",
                                    component: "engine.loop",
                                    correlation_id: correlation_ref,
                                    session_id: Some(&session_id),
                                    run_id: None,
                                    message_id: Some(&user_message_id),
                                    provider_id: Some(provider_id.as_str()),
                                    model_id,
                                    status: Some("failed"),
                                    error_code: Some(error_code),
                                    detail: Some(&detail),
                                },
                            );
                            return Err(anyhow::anyhow!(
                                "provider stream chunk error: {error_text}"
                            ));
                        }
                    };
                    match chunk {
                        StreamChunk::TextDelta(delta) => {
                            if completion.is_empty() {
                                emit_event(
                                    Level::INFO,
                                    ProcessKind::Engine,
                                    ObservabilityEvent {
                                        event: "provider.call.first_byte",
                                        component: "engine.loop",
                                        correlation_id: correlation_ref,
                                        session_id: Some(&session_id),
                                        run_id: None,
                                        message_id: Some(&user_message_id),
                                        provider_id: Some(provider_id.as_str()),
                                        model_id,
                                        status: Some("streaming"),
                                        error_code: None,
                                        detail: Some("first text delta"),
                                    },
                                );
                            }
                            completion.push_str(&delta);
                            let delta = truncate_text(&delta, 4_000);
                            let delta_part =
                                WireMessagePart::text(&session_id, &user_message_id, delta.clone());
                            self.event_bus.publish(EngineEvent::new(
                                "message.part.updated",
                                json!({"part": delta_part, "delta": delta}),
                            ));
                        }
                        StreamChunk::ReasoningDelta(_reasoning) => {}
                        StreamChunk::Done {
                            finish_reason: _,
                            usage,
                        } => {
                            if usage.is_some() {
                                provider_usage = usage;
                            }
                            break;
                        }
                        StreamChunk::ToolCallStart { id, name } => {
                            let entry = streamed_tool_calls.entry(id).or_default();
                            if entry.name.is_empty() {
                                entry.name = name;
                            }
                        }
                        StreamChunk::ToolCallDelta { id, args_delta } => {
                            let entry = streamed_tool_calls.entry(id).or_default();
                            entry.args.push_str(&args_delta);
                        }
                        StreamChunk::ToolCallEnd { id: _ } => {}
                    }
                    if cancel.is_cancelled() {
                        break;
                    }
                }

                let mut tool_calls = streamed_tool_calls
                    .into_values()
                    .filter_map(|call| {
                        if call.name.trim().is_empty() {
                            return None;
                        }
                        let tool_name = normalize_tool_name(&call.name);
                        let parsed_args = parse_streamed_tool_args(&tool_name, &call.args);
                        Some((tool_name, parsed_args))
                    })
                    .collect::<Vec<_>>();
                if tool_calls.is_empty() {
                    tool_calls = parse_tool_invocations_from_response(&completion);
                }
                if tool_calls.is_empty()
                    && !auto_workspace_probe_attempted
                    && should_force_workspace_probe(&text, &completion)
                {
                    auto_workspace_probe_attempted = true;
                    tool_calls = vec![("glob".to_string(), json!({ "pattern": "*" }))];
                }
                if !tool_calls.is_empty() {
                    let mut outputs = Vec::new();
                    let mut executed_productive_tool = false;
                    for (tool, args) in tool_calls {
                        if !agent_can_use_tool(&active_agent, &tool) {
                            continue;
                        }
                        let tool_key = normalize_tool_name(&tool);
                        if tool_key == "question" {
                            question_tool_used = true;
                        }
                        if websearch_query_blocked && tool_key == "websearch" {
                            outputs.push(
                                "Tool `websearch` call skipped: WEBSEARCH_QUERY_MISSING"
                                    .to_string(),
                            );
                            continue;
                        }
                        let entry = tool_call_counts.entry(tool_key.clone()).or_insert(0);
                        *entry += 1;
                        let budget = tool_budget_for(&tool_key);
                        if *entry > budget {
                            outputs.push(format!(
                                "Tool `{}` call skipped: per-run guard budget exceeded ({}).",
                                tool_key, budget
                            ));
                            continue;
                        }
                        let mut effective_args = args.clone();
                        if tool_key == "todo_write" {
                            effective_args = normalize_todo_write_args(effective_args, &completion);
                            if is_empty_todo_write_args(&effective_args) {
                                outputs.push(
                                    "Tool `todo_write` call skipped: empty todo payload."
                                        .to_string(),
                                );
                                continue;
                            }
                        }
                        let signature = if tool_key == "batch" {
                            batch_tool_signature(&args)
                                .unwrap_or_else(|| tool_signature(&tool_key, &args))
                        } else {
                            tool_signature(&tool_key, &args)
                        };
                        if is_shell_tool_name(&tool_key)
                            && shell_mismatch_signatures.contains(&signature)
                        {
                            outputs.push(
                                "Tool `bash` call skipped: previous invocation hit an OS/path mismatch. Use `read`, `glob`, or `grep`."
                                    .to_string(),
                            );
                            continue;
                        }
                        let mut signature_count = 1usize;
                        if is_read_only_tool(&tool_key)
                            || (tool_key == "batch" && is_read_only_batch_call(&args))
                        {
                            let count = readonly_signature_counts
                                .entry(signature.clone())
                                .and_modify(|v| *v = v.saturating_add(1))
                                .or_insert(1);
                            signature_count = *count;
                            if tool_key == "websearch" && *count > 2 {
                                self.event_bus.publish(EngineEvent::new(
                                    "tool.loop_guard.triggered",
                                    json!({
                                        "sessionID": session_id,
                                        "messageID": user_message_id,
                                        "tool": tool_key,
                                        "reason": "duplicate_signature_retry_exhausted",
                                        "queryHash": extract_websearch_query(&args).map(|q| stable_hash(&q)),
                                        "loop_guard_triggered": true
                                    }),
                                ));
                                outputs.push(
                                    "Tool `websearch` call skipped: WEBSEARCH_LOOP_GUARD"
                                        .to_string(),
                                );
                                continue;
                            }
                            if tool_key != "websearch" && *count > 1 {
                                if let Some(cached) = readonly_tool_cache.get(&signature) {
                                    outputs.push(cached.clone());
                                } else {
                                    outputs.push(format!(
                                        "Tool `{}` call skipped: duplicate call signature detected.",
                                        tool_key
                                    ));
                                }
                                continue;
                            }
                        }
                        if let Some(output) = self
                            .execute_tool_with_permission(
                                &session_id,
                                &user_message_id,
                                tool,
                                effective_args,
                                active_agent.skills.as_deref(),
                                &text,
                                Some(&completion),
                                cancel.clone(),
                            )
                            .await?
                        {
                            let productive =
                                !(tool_key == "batch" && is_non_productive_batch_output(&output));
                            if output.contains("WEBSEARCH_QUERY_MISSING") {
                                websearch_query_blocked = true;
                            }
                            if is_shell_tool_name(&tool_key) && is_os_mismatch_tool_output(&output)
                            {
                                shell_mismatch_signatures.insert(signature.clone());
                            }
                            if is_read_only_tool(&tool_key)
                                && tool_key != "websearch"
                                && signature_count == 1
                            {
                                readonly_tool_cache.insert(signature, output.clone());
                            }
                            if productive {
                                executed_productive_tool = true;
                            }
                            outputs.push(output);
                        }
                    }
                    if !outputs.is_empty() {
                        last_tool_outputs = outputs.clone();
                        if executed_productive_tool {
                            followup_context = Some(format!(
                                "{}\nContinue with a concise final response and avoid repeating identical tool calls.",
                                summarize_tool_outputs(&outputs)
                            ));
                            continue;
                        }
                        completion.clear();
                        break;
                    }
                }

                if let Some(usage) = provider_usage {
                    self.event_bus.publish(EngineEvent::new(
                        "provider.usage",
                        json!({
                            "sessionID": session_id,
                            "messageID": user_message_id,
                            "promptTokens": usage.prompt_tokens,
                            "completionTokens": usage.completion_tokens,
                            "totalTokens": usage.total_tokens,
                        }),
                    ));
                }

                break;
            }
            if completion.trim().is_empty() && !last_tool_outputs.is_empty() {
                if let Some(narrative) = self
                    .generate_final_narrative_without_tools(
                        &session_id,
                        &active_agent,
                        Some(provider_id.as_str()),
                        Some(model_id_value.as_str()),
                        cancel.clone(),
                        &last_tool_outputs,
                    )
                    .await
                {
                    completion = narrative;
                }
            }
            if completion.trim().is_empty() && !last_tool_outputs.is_empty() {
                let preview = last_tool_outputs
                    .iter()
                    .take(3)
                    .map(|o| truncate_text(o, 240))
                    .collect::<Vec<_>>()
                    .join("\n");
                completion = format!(
                    "I completed project analysis steps using tools, but the model returned no final narrative text.\n\nTool result summary:\n{}",
                    preview
                );
            }
            truncate_text(&completion, 16_000)
        };
        emit_event(
            Level::INFO,
            ProcessKind::Engine,
            ObservabilityEvent {
                event: "provider.call.finish",
                component: "engine.loop",
                correlation_id: correlation_ref,
                session_id: Some(&session_id),
                run_id: None,
                message_id: Some(&user_message_id),
                provider_id: Some(provider_id.as_str()),
                model_id,
                status: Some("ok"),
                error_code: None,
                detail: Some("provider stream complete"),
            },
        );
        if active_agent.name.eq_ignore_ascii_case("plan") {
            emit_plan_todo_fallback(
                self.storage.clone(),
                &self.event_bus,
                &session_id,
                &user_message_id,
                &completion,
            )
            .await;
            let todos_after_fallback = self.storage.get_todos(&session_id).await;
            if todos_after_fallback.is_empty() && !question_tool_used {
                emit_plan_question_fallback(
                    self.storage.clone(),
                    &self.event_bus,
                    &session_id,
                    &user_message_id,
                    &completion,
                )
                .await;
            }
        }
        if cancel.is_cancelled() {
            self.event_bus.publish(EngineEvent::new(
                "session.status",
                json!({"sessionID": session_id, "status":"cancelled"}),
            ));
            self.cancellations.remove(&session_id).await;
            return Ok(());
        }
        let assistant = Message::new(
            MessageRole::Assistant,
            vec![MessagePart::Text {
                text: completion.clone(),
            }],
        );
        let assistant_message_id = assistant.id.clone();
        self.storage.append_message(&session_id, assistant).await?;
        let final_part = WireMessagePart::text(
            &session_id,
            &assistant_message_id,
            truncate_text(&completion, 16_000),
        );
        self.event_bus.publish(EngineEvent::new(
            "message.part.updated",
            json!({"part": final_part}),
        ));
        self.event_bus.publish(EngineEvent::new(
            "session.updated",
            json!({"sessionID": session_id, "status":"idle"}),
        ));
        self.event_bus.publish(EngineEvent::new(
            "session.status",
            json!({"sessionID": session_id, "status":"idle"}),
        ));
        self.cancellations.remove(&session_id).await;
        Ok(())
    }

    pub async fn run_oneshot(&self, prompt: String) -> anyhow::Result<String> {
        self.providers.default_complete(&prompt).await
    }

    pub async fn run_oneshot_for_provider(
        &self,
        prompt: String,
        provider_id: Option<&str>,
    ) -> anyhow::Result<String> {
        self.providers
            .complete_for_provider(provider_id, &prompt, None)
            .await
    }

    #[allow(clippy::too_many_arguments)]
    async fn execute_tool_with_permission(
        &self,
        session_id: &str,
        message_id: &str,
        tool: String,
        args: Value,
        equipped_skills: Option<&[String]>,
        latest_user_text: &str,
        latest_assistant_context: Option<&str>,
        cancel: CancellationToken,
    ) -> anyhow::Result<Option<String>> {
        let tool = normalize_tool_name(&tool);
        let normalized = normalize_tool_args(
            &tool,
            args,
            latest_user_text,
            latest_assistant_context.unwrap_or_default(),
        );
        self.event_bus.publish(EngineEvent::new(
            "tool.args.normalized",
            json!({
                "sessionID": session_id,
                "messageID": message_id,
                "tool": tool,
                "argsSource": normalized.args_source,
                "argsIntegrity": normalized.args_integrity,
                "query": normalized.query,
                "queryHash": normalized.query.as_ref().map(|q| stable_hash(q)),
                "requestID": Value::Null
            }),
        ));
        if normalized.args_integrity == "recovered" {
            self.event_bus.publish(EngineEvent::new(
                "tool.args.recovered",
                json!({
                    "sessionID": session_id,
                    "messageID": message_id,
                    "tool": tool,
                    "argsSource": normalized.args_source,
                    "query": normalized.query,
                    "queryHash": normalized.query.as_ref().map(|q| stable_hash(q)),
                    "requestID": Value::Null
                }),
            ));
        }
        if normalized.missing_terminal {
            let missing_reason = normalized
                .missing_terminal_reason
                .clone()
                .unwrap_or_else(|| "TOOL_ARGUMENTS_MISSING".to_string());
            self.event_bus.publish(EngineEvent::new(
                "tool.args.missing_terminal",
                json!({
                    "sessionID": session_id,
                    "messageID": message_id,
                    "tool": tool,
                    "argsSource": normalized.args_source,
                    "argsIntegrity": normalized.args_integrity,
                    "requestID": Value::Null,
                    "error": missing_reason
                }),
            ));
            let mut failed_part =
                WireMessagePart::tool_result(session_id, message_id, tool.clone(), json!(null));
            failed_part.state = Some("failed".to_string());
            failed_part.error = Some(missing_reason.clone());
            self.event_bus.publish(EngineEvent::new(
                "message.part.updated",
                json!({"part": failed_part}),
            ));
            return Ok(Some(missing_reason));
        }

        let args = match enforce_skill_scope(&tool, normalized.args, equipped_skills) {
            Ok(args) => args,
            Err(message) => return Ok(Some(message)),
        };
        if let Some(allowed_tools) = self
            .session_allowed_tools
            .read()
            .await
            .get(session_id)
            .cloned()
        {
            if !allowed_tools.is_empty() && !allowed_tools.iter().any(|name| name == &tool) {
                return Ok(Some(format!("Tool `{tool}` is not allowed for this run.")));
            }
        }
        if let Some(hook) = self.tool_policy_hook.read().await.clone() {
            let decision = hook
                .evaluate_tool(ToolPolicyContext {
                    session_id: session_id.to_string(),
                    message_id: message_id.to_string(),
                    tool: tool.clone(),
                    args: args.clone(),
                })
                .await?;
            if !decision.allowed {
                let reason = decision
                    .reason
                    .unwrap_or_else(|| "Tool denied by runtime policy".to_string());
                let mut blocked_part =
                    WireMessagePart::tool_result(session_id, message_id, tool.clone(), json!(null));
                blocked_part.state = Some("failed".to_string());
                blocked_part.error = Some(reason.clone());
                self.event_bus.publish(EngineEvent::new(
                    "message.part.updated",
                    json!({"part": blocked_part}),
                ));
                return Ok(Some(reason));
            }
        }
        let mut tool_call_id: Option<String> = None;
        if let Some(violation) = self
            .workspace_sandbox_violation(session_id, &tool, &args)
            .await
        {
            let mut blocked_part =
                WireMessagePart::tool_result(session_id, message_id, tool.clone(), json!(null));
            blocked_part.state = Some("failed".to_string());
            blocked_part.error = Some(violation.clone());
            self.event_bus.publish(EngineEvent::new(
                "message.part.updated",
                json!({"part": blocked_part}),
            ));
            return Ok(Some(violation));
        }
        let rule = self
            .plugins
            .permission_override(&tool)
            .await
            .unwrap_or(self.permissions.evaluate(&tool, &tool).await);
        if matches!(rule, PermissionAction::Deny) {
            return Ok(Some(format!(
                "Permission denied for tool `{tool}` by policy."
            )));
        }

        let mut effective_args = args.clone();
        if matches!(rule, PermissionAction::Ask) {
            let pending = self
                .permissions
                .ask_for_session_with_context(
                    Some(session_id),
                    &tool,
                    args.clone(),
                    Some(crate::PermissionArgsContext {
                        args_source: normalized.args_source.clone(),
                        args_integrity: normalized.args_integrity.clone(),
                        query: normalized.query.clone(),
                    }),
                )
                .await;
            let mut pending_part = WireMessagePart::tool_invocation(
                session_id,
                message_id,
                tool.clone(),
                args.clone(),
            );
            pending_part.id = Some(pending.id.clone());
            tool_call_id = Some(pending.id.clone());
            pending_part.state = Some("pending".to_string());
            self.event_bus.publish(EngineEvent::new(
                "message.part.updated",
                json!({"part": pending_part}),
            ));
            let reply = self
                .permissions
                .wait_for_reply(&pending.id, cancel.clone())
                .await;
            if cancel.is_cancelled() {
                return Ok(None);
            }
            let approved = matches!(reply.as_deref(), Some("once" | "always" | "allow"));
            if !approved {
                let mut denied_part =
                    WireMessagePart::tool_result(session_id, message_id, tool.clone(), json!(null));
                denied_part.id = Some(pending.id);
                denied_part.state = Some("denied".to_string());
                denied_part.error = Some("Permission denied by user".to_string());
                self.event_bus.publish(EngineEvent::new(
                    "message.part.updated",
                    json!({"part": denied_part}),
                ));
                return Ok(Some(format!(
                    "Permission denied for tool `{tool}` by user."
                )));
            }
            effective_args = args;
        }

        let mut args = self.plugins.inject_tool_args(&tool, effective_args).await;
        let tool_context = self.resolve_tool_execution_context(session_id).await;
        if let Some((workspace_root, effective_cwd)) = tool_context.as_ref() {
            if let Some(obj) = args.as_object_mut() {
                obj.insert(
                    "__workspace_root".to_string(),
                    Value::String(workspace_root.clone()),
                );
                obj.insert(
                    "__effective_cwd".to_string(),
                    Value::String(effective_cwd.clone()),
                );
            }
            tracing::info!(
                "tool execution context session_id={} tool={} workspace_root={} effective_cwd={}",
                session_id,
                tool,
                workspace_root,
                effective_cwd
            );
        }
        let mut invoke_part =
            WireMessagePart::tool_invocation(session_id, message_id, tool.clone(), args.clone());
        if let Some(call_id) = tool_call_id.clone() {
            invoke_part.id = Some(call_id);
        }
        let invoke_part_id = invoke_part.id.clone();
        self.event_bus.publish(EngineEvent::new(
            "message.part.updated",
            json!({"part": invoke_part}),
        ));
        let args_for_side_events = args.clone();
        if tool == "spawn_agent" {
            let hook = self.spawn_agent_hook.read().await.clone();
            if let Some(hook) = hook {
                let spawned = hook
                    .spawn_agent(SpawnAgentToolContext {
                        session_id: session_id.to_string(),
                        message_id: message_id.to_string(),
                        tool_call_id: invoke_part_id.clone(),
                        args: args_for_side_events.clone(),
                    })
                    .await?;
                let output = self.plugins.transform_tool_output(spawned.output).await;
                let output = truncate_text(&output, 16_000);
                emit_tool_side_events(
                    self.storage.clone(),
                    &self.event_bus,
                    session_id,
                    message_id,
                    &tool,
                    &args_for_side_events,
                    &spawned.metadata,
                    tool_context.as_ref().map(|ctx| ctx.0.as_str()),
                    tool_context.as_ref().map(|ctx| ctx.1.as_str()),
                )
                .await;
                let mut result_part = WireMessagePart::tool_result(
                    session_id,
                    message_id,
                    tool.clone(),
                    json!(output.clone()),
                );
                result_part.id = invoke_part_id;
                self.event_bus.publish(EngineEvent::new(
                    "message.part.updated",
                    json!({"part": result_part}),
                ));
                return Ok(Some(truncate_text(
                    &format!("Tool `{tool}` result:\n{output}"),
                    16_000,
                )));
            }
            let output = "spawn_agent is unavailable in this runtime (no spawn hook installed).";
            let mut failed_part =
                WireMessagePart::tool_result(session_id, message_id, tool.clone(), json!(null));
            failed_part.id = invoke_part_id.clone();
            failed_part.state = Some("failed".to_string());
            failed_part.error = Some(output.to_string());
            self.event_bus.publish(EngineEvent::new(
                "message.part.updated",
                json!({"part": failed_part}),
            ));
            return Ok(Some(output.to_string()));
        }
        let result = match self
            .tools
            .execute_with_cancel(&tool, args, cancel.clone())
            .await
        {
            Ok(result) => result,
            Err(err) => {
                let mut failed_part =
                    WireMessagePart::tool_result(session_id, message_id, tool.clone(), json!(null));
                failed_part.id = invoke_part_id.clone();
                failed_part.state = Some("failed".to_string());
                failed_part.error = Some(err.to_string());
                self.event_bus.publish(EngineEvent::new(
                    "message.part.updated",
                    json!({"part": failed_part}),
                ));
                return Err(err);
            }
        };
        emit_tool_side_events(
            self.storage.clone(),
            &self.event_bus,
            session_id,
            message_id,
            &tool,
            &args_for_side_events,
            &result.metadata,
            tool_context.as_ref().map(|ctx| ctx.0.as_str()),
            tool_context.as_ref().map(|ctx| ctx.1.as_str()),
        )
        .await;
        let output = self.plugins.transform_tool_output(result.output).await;
        let output = truncate_text(&output, 16_000);
        let mut result_part = WireMessagePart::tool_result(
            session_id,
            message_id,
            tool.clone(),
            json!(output.clone()),
        );
        result_part.id = invoke_part_id;
        self.event_bus.publish(EngineEvent::new(
            "message.part.updated",
            json!({"part": result_part}),
        ));
        Ok(Some(truncate_text(
            &format!("Tool `{tool}` result:\n{output}"),
            16_000,
        )))
    }

    async fn find_recent_matching_user_message_id(
        &self,
        session_id: &str,
        text: &str,
    ) -> Option<String> {
        let session = self.storage.get_session(session_id).await?;
        let last = session.messages.last()?;
        if !matches!(last.role, MessageRole::User) {
            return None;
        }
        let age_ms = (Utc::now() - last.created_at).num_milliseconds().max(0) as u64;
        if age_ms > 10_000 {
            return None;
        }
        let last_text = last
            .parts
            .iter()
            .filter_map(|part| match part {
                MessagePart::Text { text } => Some(text.clone()),
                _ => None,
            })
            .collect::<Vec<_>>()
            .join("\n");
        if last_text == text {
            return Some(last.id.clone());
        }
        None
    }

    async fn auto_rename_session_from_user_text(&self, session_id: &str, fallback_text: &str) {
        let Some(mut session) = self.storage.get_session(session_id).await else {
            return;
        };
        if !title_needs_repair(&session.title) {
            return;
        }

        let first_user_text = session.messages.iter().find_map(|message| {
            if !matches!(message.role, MessageRole::User) {
                return None;
            }
            message.parts.iter().find_map(|part| match part {
                MessagePart::Text { text } if !text.trim().is_empty() => Some(text.clone()),
                _ => None,
            })
        });

        let source = first_user_text.unwrap_or_else(|| fallback_text.to_string());
        let Some(title) = derive_session_title_from_prompt(&source, 60) else {
            return;
        };

        session.title = title;
        session.time.updated = Utc::now();
        let _ = self.storage.save_session(session).await;
    }

    async fn workspace_sandbox_violation(
        &self,
        session_id: &str,
        tool: &str,
        args: &Value,
    ) -> Option<String> {
        if self.workspace_override_active(session_id).await {
            return None;
        }
        let session = self.storage.get_session(session_id).await?;
        let workspace = session
            .workspace_root
            .or_else(|| crate::normalize_workspace_path(&session.directory))?;
        let workspace_path = PathBuf::from(&workspace);
        let candidate_paths = extract_tool_candidate_paths(tool, args);
        if candidate_paths.is_empty() {
            if is_shell_tool_name(tool) {
                if let Some(command) = extract_shell_command(args) {
                    if shell_command_targets_sensitive_path(&command) {
                        return Some(format!(
                            "Sandbox blocked `{tool}` command targeting sensitive paths."
                        ));
                    }
                }
            }
            return None;
        }
        if let Some(sensitive) = candidate_paths.iter().find(|path| {
            let raw = Path::new(path);
            let resolved = if raw.is_absolute() {
                raw.to_path_buf()
            } else {
                workspace_path.join(raw)
            };
            is_sensitive_path_candidate(&resolved)
        }) {
            return Some(format!(
                "Sandbox blocked `{tool}` path `{sensitive}` (sensitive path policy)."
            ));
        }

        let outside = candidate_paths.iter().find(|path| {
            let raw = Path::new(path);
            let resolved = if raw.is_absolute() {
                raw.to_path_buf()
            } else {
                workspace_path.join(raw)
            };
            !crate::is_within_workspace_root(&resolved, &workspace_path)
        })?;
        Some(format!(
            "Sandbox blocked `{tool}` path `{outside}` (workspace root: `{workspace}`)"
        ))
    }

    async fn resolve_tool_execution_context(&self, session_id: &str) -> Option<(String, String)> {
        let session = self.storage.get_session(session_id).await?;
        let workspace_root = session
            .workspace_root
            .or_else(|| crate::normalize_workspace_path(&session.directory))?;
        let effective_cwd = if session.directory.trim().is_empty()
            || session.directory.trim() == "."
        {
            workspace_root.clone()
        } else {
            crate::normalize_workspace_path(&session.directory).unwrap_or(workspace_root.clone())
        };
        Some((workspace_root, effective_cwd))
    }

    async fn workspace_override_active(&self, session_id: &str) -> bool {
        let now = chrono::Utc::now().timestamp_millis().max(0) as u64;
        let mut overrides = self.workspace_overrides.write().await;
        overrides.retain(|_, expires_at| *expires_at > now);
        overrides
            .get(session_id)
            .map(|expires_at| *expires_at > now)
            .unwrap_or(false)
    }

    async fn generate_final_narrative_without_tools(
        &self,
        session_id: &str,
        active_agent: &AgentDefinition,
        provider_hint: Option<&str>,
        model_id: Option<&str>,
        cancel: CancellationToken,
        tool_outputs: &[String],
    ) -> Option<String> {
        if cancel.is_cancelled() {
            return None;
        }
        let mut messages = load_chat_history(self.storage.clone(), session_id).await;
        let mut system_parts = vec![tandem_runtime_system_prompt(&self.host_runtime_context)];
        if let Some(system) = active_agent.system_prompt.as_ref() {
            system_parts.push(system.clone());
        }
        messages.insert(
            0,
            ChatMessage {
                role: "system".to_string(),
                content: system_parts.join("\n\n"),
            },
        );
        messages.push(ChatMessage {
            role: "user".to_string(),
            content: format!(
                "Tool observations:\n{}\n\nProvide a direct final answer now. Do not call tools.",
                summarize_tool_outputs(tool_outputs)
            ),
        });
        let stream = self
            .providers
            .stream_for_provider(provider_hint, model_id, messages, None, cancel.clone())
            .await
            .ok()?;
        tokio::pin!(stream);
        let mut completion = String::new();
        while let Some(chunk) = stream.next().await {
            if cancel.is_cancelled() {
                return None;
            }
            match chunk {
                Ok(StreamChunk::TextDelta(delta)) => completion.push_str(&delta),
                Ok(StreamChunk::Done { .. }) => break,
                Ok(_) => {}
                Err(_) => return None,
            }
        }
        let completion = truncate_text(&completion, 16_000);
        if completion.trim().is_empty() {
            None
        } else {
            Some(completion)
        }
    }
}

fn resolve_model_route(
    request_model: Option<&ModelSpec>,
    session_model: Option<&ModelSpec>,
) -> Option<(String, String)> {
    fn normalize(spec: &ModelSpec) -> Option<(String, String)> {
        let provider_id = spec.provider_id.trim();
        let model_id = spec.model_id.trim();
        if provider_id.is_empty() || model_id.is_empty() {
            return None;
        }
        Some((provider_id.to_string(), model_id.to_string()))
    }

    request_model
        .and_then(normalize)
        .or_else(|| session_model.and_then(normalize))
}

fn truncate_text(input: &str, max_len: usize) -> String {
    if input.len() <= max_len {
        return input.to_string();
    }
    let mut out = input[..max_len].to_string();
    out.push_str("...<truncated>");
    out
}

fn provider_error_code(error_text: &str) -> &'static str {
    let lower = error_text.to_lowercase();
    if lower.contains("invalid_function_parameters")
        || lower.contains("array schema missing items")
        || lower.contains("tool schema")
    {
        return "TOOL_SCHEMA_INVALID";
    }
    if lower.contains("rate limit") || lower.contains("too many requests") || lower.contains("429")
    {
        return "RATE_LIMIT_EXCEEDED";
    }
    if lower.contains("context length")
        || lower.contains("max tokens")
        || lower.contains("token limit")
    {
        return "CONTEXT_LENGTH_EXCEEDED";
    }
    if lower.contains("unauthorized")
        || lower.contains("authentication")
        || lower.contains("401")
        || lower.contains("403")
    {
        return "AUTHENTICATION_ERROR";
    }
    if lower.contains("timeout") || lower.contains("timed out") {
        return "TIMEOUT";
    }
    if lower.contains("server error")
        || lower.contains("500")
        || lower.contains("502")
        || lower.contains("503")
        || lower.contains("504")
    {
        return "PROVIDER_SERVER_ERROR";
    }
    "PROVIDER_REQUEST_FAILED"
}

fn normalize_tool_name(name: &str) -> String {
    let mut normalized = name.trim().to_ascii_lowercase().replace('-', "_");
    for prefix in [
        "default_api:",
        "default_api.",
        "functions.",
        "function.",
        "tools.",
        "tool.",
        "builtin:",
        "builtin.",
    ] {
        if let Some(rest) = normalized.strip_prefix(prefix) {
            let trimmed = rest.trim();
            if !trimmed.is_empty() {
                normalized = trimmed.to_string();
                break;
            }
        }
    }
    match normalized.as_str() {
        "todowrite" | "update_todo_list" | "update_todos" => "todo_write".to_string(),
        "run_command" | "shell" | "powershell" | "cmd" => "bash".to_string(),
        other => other.to_string(),
    }
}

fn extract_tool_candidate_paths(tool: &str, args: &Value) -> Vec<String> {
    let Some(obj) = args.as_object() else {
        return Vec::new();
    };
    let keys: &[&str] = match tool {
        "read" | "write" | "edit" | "grep" | "codesearch" => &["path", "filePath", "cwd"],
        "glob" => &["pattern"],
        "lsp" => &["filePath", "path"],
        "bash" => &["cwd"],
        "apply_patch" => &[],
        _ => &["path", "cwd"],
    };
    keys.iter()
        .filter_map(|key| obj.get(*key))
        .filter_map(|value| value.as_str())
        .filter(|s| !s.trim().is_empty())
        .map(ToString::to_string)
        .collect()
}

fn agent_can_use_tool(agent: &AgentDefinition, tool_name: &str) -> bool {
    let target = normalize_tool_name(tool_name);
    match agent.tools.as_ref() {
        None => true,
        Some(list) => list.iter().any(|t| normalize_tool_name(t) == target),
    }
}

fn enforce_skill_scope(
    tool_name: &str,
    args: Value,
    equipped_skills: Option<&[String]>,
) -> Result<Value, String> {
    if normalize_tool_name(tool_name) != "skill" {
        return Ok(args);
    }
    let Some(configured) = equipped_skills else {
        return Ok(args);
    };

    let mut allowed = configured
        .iter()
        .map(|s| s.trim().to_string())
        .filter(|s| !s.is_empty())
        .collect::<Vec<_>>();
    if allowed
        .iter()
        .any(|s| s == "*" || s.eq_ignore_ascii_case("all"))
    {
        return Ok(args);
    }
    allowed.sort();
    allowed.dedup();
    if allowed.is_empty() {
        return Err("No skills are equipped for this agent.".to_string());
    }

    let requested = args
        .get("name")
        .and_then(|v| v.as_str())
        .map(|v| v.trim().to_string())
        .unwrap_or_default();
    if !requested.is_empty() && !allowed.iter().any(|s| s == &requested) {
        return Err(format!(
            "Skill '{}' is not equipped for this agent. Equipped skills: {}",
            requested,
            allowed.join(", ")
        ));
    }

    let mut out = if let Some(obj) = args.as_object() {
        Value::Object(obj.clone())
    } else {
        json!({})
    };
    if let Some(obj) = out.as_object_mut() {
        obj.insert("allowed_skills".to_string(), json!(allowed));
    }
    Ok(out)
}

fn is_read_only_tool(tool_name: &str) -> bool {
    matches!(
        normalize_tool_name(tool_name).as_str(),
        "glob"
            | "read"
            | "grep"
            | "search"
            | "codesearch"
            | "list"
            | "ls"
            | "lsp"
            | "websearch"
            | "webfetch"
            | "webfetch_html"
    )
}

fn is_batch_wrapper_tool_name(name: &str) -> bool {
    matches!(
        normalize_tool_name(name).as_str(),
        "default_api" | "default" | "api" | "function" | "functions" | "tool" | "tools"
    )
}

fn non_empty_string_at<'a>(obj: &'a Map<String, Value>, key: &str) -> Option<&'a str> {
    obj.get(key)
        .and_then(|v| v.as_str())
        .map(str::trim)
        .filter(|s| !s.is_empty())
}

fn nested_non_empty_string_at<'a>(
    obj: &'a Map<String, Value>,
    parent: &str,
    key: &str,
) -> Option<&'a str> {
    obj.get(parent)
        .and_then(|v| v.as_object())
        .and_then(|nested| nested.get(key))
        .and_then(|v| v.as_str())
        .map(str::trim)
        .filter(|s| !s.is_empty())
}

fn extract_batch_calls(args: &Value) -> Vec<(String, Value)> {
    let calls = args
        .get("tool_calls")
        .and_then(|v| v.as_array())
        .cloned()
        .unwrap_or_default();
    calls
        .into_iter()
        .filter_map(|call| {
            let obj = call.as_object()?;
            let tool_raw = non_empty_string_at(obj, "tool")
                .or_else(|| nested_non_empty_string_at(obj, "tool", "name"))
                .or_else(|| nested_non_empty_string_at(obj, "function", "tool"))
                .or_else(|| nested_non_empty_string_at(obj, "function_call", "tool"))
                .or_else(|| nested_non_empty_string_at(obj, "call", "tool"));
            let name_raw = non_empty_string_at(obj, "name")
                .or_else(|| nested_non_empty_string_at(obj, "function", "name"))
                .or_else(|| nested_non_empty_string_at(obj, "function_call", "name"))
                .or_else(|| nested_non_empty_string_at(obj, "call", "name"))
                .or_else(|| nested_non_empty_string_at(obj, "tool", "name"));
            let effective = match (tool_raw, name_raw) {
                (Some(t), Some(n)) if is_batch_wrapper_tool_name(t) => n,
                (Some(t), _) => t,
                (None, Some(n)) => n,
                (None, None) => return None,
            };
            let normalized = normalize_tool_name(effective);
            let call_args = obj.get("args").cloned().unwrap_or_else(|| json!({}));
            Some((normalized, call_args))
        })
        .collect()
}

fn is_read_only_batch_call(args: &Value) -> bool {
    let calls = extract_batch_calls(args);
    !calls.is_empty() && calls.iter().all(|(tool, _)| is_read_only_tool(tool))
}

fn batch_tool_signature(args: &Value) -> Option<String> {
    let calls = extract_batch_calls(args);
    if calls.is_empty() {
        return None;
    }
    let parts = calls
        .into_iter()
        .map(|(tool, call_args)| tool_signature(&tool, &call_args))
        .collect::<Vec<_>>();
    Some(format!("batch:{}", parts.join("|")))
}

fn is_non_productive_batch_output(output: &str) -> bool {
    let Ok(value) = serde_json::from_str::<Value>(output.trim()) else {
        return false;
    };
    let Some(items) = value.as_array() else {
        return false;
    };
    if items.is_empty() {
        return true;
    }
    items.iter().all(|item| {
        let text = item
            .get("output")
            .and_then(|v| v.as_str())
            .map(str::trim)
            .unwrap_or_default()
            .to_ascii_lowercase();
        text.is_empty()
            || text.starts_with("unknown tool:")
            || text.contains("call skipped")
            || text.contains("guard budget exceeded")
    })
}

fn tool_budget_for(tool_name: &str) -> usize {
    match normalize_tool_name(tool_name).as_str() {
        "glob" => 4,
        "read" => 8,
        "websearch" => 3,
        "batch" => 4,
        "grep" | "search" | "codesearch" => 6,
        _ => 10,
    }
}

fn is_sensitive_path_candidate(path: &Path) -> bool {
    let lowered = path.to_string_lossy().to_ascii_lowercase();
    if lowered.contains("/.ssh/")
        || lowered.ends_with("/.ssh")
        || lowered.contains("/.gnupg/")
        || lowered.ends_with("/.gnupg")
    {
        return true;
    }
    if lowered.contains("/.aws/credentials")
        || lowered.ends_with("/.npmrc")
        || lowered.ends_with("/.netrc")
        || lowered.ends_with("/.pypirc")
    {
        return true;
    }
    if lowered.contains("id_rsa")
        || lowered.contains("id_ed25519")
        || lowered.contains("id_ecdsa")
        || lowered.contains(".pem")
        || lowered.contains(".p12")
        || lowered.contains(".pfx")
        || lowered.contains(".key")
    {
        return true;
    }
    if let Some(name) = path.file_name().and_then(|n| n.to_str()) {
        let n = name.to_ascii_lowercase();
        if n == ".env" || n.starts_with(".env.") {
            return true;
        }
    }
    false
}

fn shell_command_targets_sensitive_path(command: &str) -> bool {
    let lower = command.to_ascii_lowercase();
    let patterns = [
        ".env",
        ".ssh",
        ".gnupg",
        ".aws/credentials",
        "id_rsa",
        "id_ed25519",
        ".pem",
        ".p12",
        ".pfx",
        ".key",
    ];
    patterns.iter().any(|p| lower.contains(p))
}

#[derive(Debug, Clone)]
struct NormalizedToolArgs {
    args: Value,
    args_source: String,
    args_integrity: String,
    query: Option<String>,
    missing_terminal: bool,
    missing_terminal_reason: Option<String>,
}

fn normalize_tool_args(
    tool_name: &str,
    raw_args: Value,
    latest_user_text: &str,
    latest_assistant_context: &str,
) -> NormalizedToolArgs {
    let normalized_tool = normalize_tool_name(tool_name);
    let mut args = raw_args;
    let mut args_source = if args.is_string() {
        "provider_string".to_string()
    } else {
        "provider_json".to_string()
    };
    let mut args_integrity = "ok".to_string();
    let mut query = None;
    let mut missing_terminal = false;
    let mut missing_terminal_reason = None;

    if normalized_tool == "websearch" {
        if let Some(found) = extract_websearch_query(&args) {
            query = Some(found);
            args = set_websearch_query_and_source(args, query.clone(), "tool_args");
        } else if let Some(inferred) = infer_websearch_query_from_text(latest_user_text) {
            args_source = "inferred_from_user".to_string();
            args_integrity = "recovered".to_string();
            query = Some(inferred);
            args = set_websearch_query_and_source(args, query.clone(), "inferred_from_user");
        } else if let Some(recovered) = infer_websearch_query_from_text(latest_assistant_context) {
            args_source = "recovered_from_context".to_string();
            args_integrity = "recovered".to_string();
            query = Some(recovered);
            args = set_websearch_query_and_source(args, query.clone(), "recovered_from_context");
        } else {
            args_source = "missing".to_string();
            args_integrity = "empty".to_string();
            missing_terminal = true;
            missing_terminal_reason = Some("WEBSEARCH_QUERY_MISSING".to_string());
        }
    } else if is_shell_tool_name(&normalized_tool) {
        if let Some(command) = extract_shell_command(&args) {
            args = set_shell_command(args, command);
        } else if let Some(inferred) = infer_shell_command_from_text(latest_assistant_context) {
            args_source = "inferred_from_context".to_string();
            args_integrity = "recovered".to_string();
            args = set_shell_command(args, inferred);
        } else if let Some(inferred) = infer_shell_command_from_text(latest_user_text) {
            args_source = "inferred_from_user".to_string();
            args_integrity = "recovered".to_string();
            args = set_shell_command(args, inferred);
        } else {
            args_source = "missing".to_string();
            args_integrity = "empty".to_string();
            missing_terminal = true;
            missing_terminal_reason = Some("BASH_COMMAND_MISSING".to_string());
        }
    } else if matches!(normalized_tool.as_str(), "read" | "write" | "edit") {
        if let Some(path) = extract_file_path_arg(&args) {
            args = set_file_path_arg(args, path);
        } else if let Some(inferred) = infer_file_path_from_text(latest_assistant_context) {
            args_source = "inferred_from_context".to_string();
            args_integrity = "recovered".to_string();
            args = set_file_path_arg(args, inferred);
        } else if let Some(inferred) = infer_file_path_from_text(latest_user_text) {
            args_source = "inferred_from_user".to_string();
            args_integrity = "recovered".to_string();
            args = set_file_path_arg(args, inferred);
        } else {
            args_source = "missing".to_string();
            args_integrity = "empty".to_string();
            missing_terminal = true;
            missing_terminal_reason = Some("FILE_PATH_MISSING".to_string());
        }

        if !missing_terminal && normalized_tool == "write" {
            if let Some(content) = extract_write_content_arg(&args) {
                args = set_write_content_arg(args, content);
            } else {
                args_source = "missing".to_string();
                args_integrity = "empty".to_string();
                missing_terminal = true;
                missing_terminal_reason = Some("WRITE_CONTENT_MISSING".to_string());
            }
        }
    }

    NormalizedToolArgs {
        args,
        args_source,
        args_integrity,
        query,
        missing_terminal,
        missing_terminal_reason,
    }
}

fn is_shell_tool_name(tool_name: &str) -> bool {
    matches!(
        tool_name.trim().to_ascii_lowercase().as_str(),
        "bash" | "shell" | "powershell" | "cmd"
    )
}

fn set_file_path_arg(args: Value, path: String) -> Value {
    let mut obj = args.as_object().cloned().unwrap_or_default();
    obj.insert("path".to_string(), Value::String(path));
    Value::Object(obj)
}

fn set_write_content_arg(args: Value, content: String) -> Value {
    let mut obj = args.as_object().cloned().unwrap_or_default();
    obj.insert("content".to_string(), Value::String(content));
    Value::Object(obj)
}

fn extract_file_path_arg(args: &Value) -> Option<String> {
    extract_file_path_arg_internal(args, 0)
}

fn extract_write_content_arg(args: &Value) -> Option<String> {
    extract_write_content_arg_internal(args, 0)
}

fn extract_file_path_arg_internal(args: &Value, depth: usize) -> Option<String> {
    if depth > 5 {
        return None;
    }

    match args {
        Value::String(raw) => {
            let trimmed = raw.trim();
            if trimmed.is_empty() {
                return None;
            }
            // If the provider sent plain string args, treat it as a path directly.
            if !(trimmed.starts_with('{') || trimmed.starts_with('[') || trimmed.starts_with('"')) {
                return sanitize_path_candidate(trimmed);
            }
            if let Ok(parsed) = serde_json::from_str::<Value>(trimmed) {
                return extract_file_path_arg_internal(&parsed, depth + 1);
            }
            sanitize_path_candidate(trimmed)
        }
        Value::Array(items) => items
            .iter()
            .find_map(|item| extract_file_path_arg_internal(item, depth + 1)),
        Value::Object(obj) => {
            for key in FILE_PATH_KEYS {
                if let Some(raw) = obj.get(key).and_then(|v| v.as_str()) {
                    if let Some(path) = sanitize_path_candidate(raw) {
                        return Some(path);
                    }
                }
            }
            for container in NESTED_ARGS_KEYS {
                if let Some(nested) = obj.get(container) {
                    if let Some(path) = extract_file_path_arg_internal(nested, depth + 1) {
                        return Some(path);
                    }
                }
            }
            None
        }
        _ => None,
    }
}

fn extract_write_content_arg_internal(args: &Value, depth: usize) -> Option<String> {
    if depth > 5 {
        return None;
    }

    match args {
        Value::String(raw) => {
            let trimmed = raw.trim();
            if trimmed.is_empty() {
                return None;
            }
            if let Ok(parsed) = serde_json::from_str::<Value>(trimmed) {
                return extract_write_content_arg_internal(&parsed, depth + 1);
            }
            // Some providers collapse args to a plain string. Recover as content only when
            // it does not look like a standalone file path token.
            if sanitize_path_candidate(trimmed).is_some()
                && !trimmed.contains('\n')
                && trimmed.split_whitespace().count() <= 3
            {
                return None;
            }
            Some(trimmed.to_string())
        }
        Value::Array(items) => items
            .iter()
            .find_map(|item| extract_write_content_arg_internal(item, depth + 1)),
        Value::Object(obj) => {
            for key in WRITE_CONTENT_KEYS {
                if let Some(value) = obj.get(key) {
                    if let Some(raw) = value.as_str() {
                        if !raw.is_empty() {
                            return Some(raw.to_string());
                        }
                    } else if let Some(recovered) =
                        extract_write_content_arg_internal(value, depth + 1)
                    {
                        return Some(recovered);
                    }
                }
            }
            for container in NESTED_ARGS_KEYS {
                if let Some(nested) = obj.get(container) {
                    if let Some(content) = extract_write_content_arg_internal(nested, depth + 1) {
                        return Some(content);
                    }
                }
            }
            None
        }
        _ => None,
    }
}

fn set_shell_command(args: Value, command: String) -> Value {
    let mut obj = args.as_object().cloned().unwrap_or_default();
    obj.insert("command".to_string(), Value::String(command));
    Value::Object(obj)
}

fn extract_shell_command(args: &Value) -> Option<String> {
    extract_shell_command_internal(args, 0)
}

fn extract_shell_command_internal(args: &Value, depth: usize) -> Option<String> {
    if depth > 5 {
        return None;
    }

    match args {
        Value::String(raw) => {
            let trimmed = raw.trim();
            if trimmed.is_empty() {
                return None;
            }
            if !(trimmed.starts_with('{') || trimmed.starts_with('[') || trimmed.starts_with('"')) {
                return sanitize_shell_command_candidate(trimmed);
            }
            if let Ok(parsed) = serde_json::from_str::<Value>(trimmed) {
                return extract_shell_command_internal(&parsed, depth + 1);
            }
            sanitize_shell_command_candidate(trimmed)
        }
        Value::Array(items) => items
            .iter()
            .find_map(|item| extract_shell_command_internal(item, depth + 1)),
        Value::Object(obj) => {
            for key in SHELL_COMMAND_KEYS {
                if let Some(raw) = obj.get(key).and_then(|v| v.as_str()) {
                    if let Some(command) = sanitize_shell_command_candidate(raw) {
                        return Some(command);
                    }
                }
            }
            for container in NESTED_ARGS_KEYS {
                if let Some(nested) = obj.get(container) {
                    if let Some(command) = extract_shell_command_internal(nested, depth + 1) {
                        return Some(command);
                    }
                }
            }
            None
        }
        _ => None,
    }
}

fn infer_shell_command_from_text(text: &str) -> Option<String> {
    let trimmed = text.trim();
    if trimmed.is_empty() {
        return None;
    }

    // Prefer explicit backtick commands first.
    let mut in_tick = false;
    let mut tick_buf = String::new();
    for ch in trimmed.chars() {
        if ch == '`' {
            if in_tick {
                if let Some(candidate) = sanitize_shell_command_candidate(&tick_buf) {
                    if looks_like_shell_command(&candidate) {
                        return Some(candidate);
                    }
                }
                tick_buf.clear();
            }
            in_tick = !in_tick;
            continue;
        }
        if in_tick {
            tick_buf.push(ch);
        }
    }

    for line in trimmed.lines() {
        let line = line.trim();
        if line.is_empty() {
            continue;
        }
        let lower = line.to_ascii_lowercase();
        for prefix in [
            "run ",
            "execute ",
            "call ",
            "use bash ",
            "use shell ",
            "bash ",
            "shell ",
            "powershell ",
            "pwsh ",
        ] {
            if lower.starts_with(prefix) {
                let candidate = line[prefix.len()..].trim();
                if let Some(command) = sanitize_shell_command_candidate(candidate) {
                    if looks_like_shell_command(&command) {
                        return Some(command);
                    }
                }
            }
        }
    }

    None
}

fn set_websearch_query_and_source(args: Value, query: Option<String>, query_source: &str) -> Value {
    let mut obj = args.as_object().cloned().unwrap_or_default();
    if let Some(q) = query {
        obj.insert("query".to_string(), Value::String(q));
    }
    obj.insert(
        "__query_source".to_string(),
        Value::String(query_source.to_string()),
    );
    Value::Object(obj)
}

fn extract_websearch_query(args: &Value) -> Option<String> {
    const QUERY_KEYS: [&str; 5] = ["query", "q", "search_query", "searchQuery", "keywords"];
    for key in QUERY_KEYS {
        if let Some(value) = args.get(key).and_then(|v| v.as_str()) {
            let trimmed = value.trim();
            if !trimmed.is_empty() {
                return Some(trimmed.to_string());
            }
        }
    }
    for container in ["arguments", "args", "input", "params"] {
        if let Some(obj) = args.get(container) {
            for key in QUERY_KEYS {
                if let Some(value) = obj.get(key).and_then(|v| v.as_str()) {
                    let trimmed = value.trim();
                    if !trimmed.is_empty() {
                        return Some(trimmed.to_string());
                    }
                }
            }
        }
    }
    args.as_str()
        .map(str::trim)
        .filter(|s| !s.is_empty())
        .map(ToString::to_string)
}

fn infer_websearch_query_from_text(text: &str) -> Option<String> {
    let trimmed = text.trim();
    if trimmed.is_empty() {
        return None;
    }

    let lower = trimmed.to_lowercase();
    const PREFIXES: [&str; 11] = [
        "web search",
        "websearch",
        "search web for",
        "search web",
        "search for",
        "search",
        "look up",
        "lookup",
        "find",
        "web lookup",
        "query",
    ];

    let mut candidate = trimmed;
    for prefix in PREFIXES {
        if lower.starts_with(prefix) && lower.len() >= prefix.len() {
            let remainder = trimmed[prefix.len()..]
                .trim_start_matches(|c: char| c.is_whitespace() || c == ':' || c == '-');
            candidate = remainder;
            break;
        }
    }

    let normalized = candidate
        .trim()
        .trim_matches(|c: char| c == '"' || c == '\'' || c.is_whitespace())
        .trim_matches(|c: char| matches!(c, '.' | ',' | '!' | '?'))
        .trim()
        .to_string();

    if normalized.split_whitespace().count() < 2 {
        return None;
    }
    Some(normalized)
}

fn infer_file_path_from_text(text: &str) -> Option<String> {
    let trimmed = text.trim();
    if trimmed.is_empty() {
        return None;
    }

    let mut candidates: Vec<String> = Vec::new();

    // Prefer backtick-delimited paths when available.
    let mut in_tick = false;
    let mut tick_buf = String::new();
    for ch in trimmed.chars() {
        if ch == '`' {
            if in_tick {
                let cand = sanitize_path_candidate(&tick_buf);
                if let Some(path) = cand {
                    candidates.push(path);
                }
                tick_buf.clear();
            }
            in_tick = !in_tick;
            continue;
        }
        if in_tick {
            tick_buf.push(ch);
        }
    }

    // Fallback: scan whitespace tokens.
    for raw in trimmed.split_whitespace() {
        if let Some(path) = sanitize_path_candidate(raw) {
            candidates.push(path);
        }
    }

    let mut deduped = Vec::new();
    let mut seen = HashSet::new();
    for candidate in candidates {
        if seen.insert(candidate.clone()) {
            deduped.push(candidate);
        }
    }

    deduped.into_iter().next()
}

fn sanitize_path_candidate(raw: &str) -> Option<String> {
    let token = raw
        .trim()
        .trim_matches(|c: char| matches!(c, '`' | '"' | '\'' | '*' | '|'))
        .trim_start_matches(['(', '[', '{', '<'])
        .trim_end_matches([',', ';', ':', ')', ']', '}', '>'])
        .trim_end_matches('.')
        .trim();

    if token.is_empty() {
        return None;
    }
    let lower = token.to_ascii_lowercase();
    if lower.starts_with("http://") || lower.starts_with("https://") {
        return None;
    }
    if is_malformed_tool_path_token(token) {
        return None;
    }
    if is_root_only_path_token(token) {
        return None;
    }

    let looks_like_path = token.contains('/') || token.contains('\\');
    let has_file_ext = [
        ".md", ".txt", ".json", ".yaml", ".yml", ".toml", ".rs", ".ts", ".tsx", ".js", ".jsx",
        ".py", ".go", ".java", ".cpp", ".c", ".h",
    ]
    .iter()
    .any(|ext| lower.ends_with(ext));

    if !looks_like_path && !has_file_ext {
        return None;
    }

    Some(token.to_string())
}

fn is_malformed_tool_path_token(token: &str) -> bool {
    let lower = token.to_ascii_lowercase();
    // XML-ish tool-call wrappers emitted by some model responses.
    if lower.contains("<tool_call")
        || lower.contains("</tool_call")
        || lower.contains("<function=")
        || lower.contains("<parameter=")
        || lower.contains("</function>")
        || lower.contains("</parameter>")
    {
        return true;
    }
    // Multiline payloads are not valid single file paths.
    if token.contains('\n') || token.contains('\r') {
        return true;
    }
    // Glob patterns are not concrete file paths for read/write/edit.
    if token.contains('*') || token.contains('?') {
        return true;
    }
    false
}

fn is_root_only_path_token(token: &str) -> bool {
    let trimmed = token.trim();
    if trimmed.is_empty() {
        return true;
    }
    if matches!(trimmed, "/" | "\\" | "." | ".." | "~") {
        return true;
    }
    // Windows drive root placeholders, e.g. `C:` or `C:\`.
    let bytes = trimmed.as_bytes();
    if bytes.len() == 2 && bytes[1] == b':' && (bytes[0] as char).is_ascii_alphabetic() {
        return true;
    }
    if bytes.len() == 3
        && bytes[1] == b':'
        && (bytes[0] as char).is_ascii_alphabetic()
        && (bytes[2] == b'\\' || bytes[2] == b'/')
    {
        return true;
    }
    false
}

fn sanitize_shell_command_candidate(raw: &str) -> Option<String> {
    let token = raw
        .trim()
        .trim_matches(|c: char| matches!(c, '`' | '"' | '\'' | ',' | ';'))
        .trim();
    if token.is_empty() {
        return None;
    }
    Some(token.to_string())
}

fn looks_like_shell_command(candidate: &str) -> bool {
    let lower = candidate.to_ascii_lowercase();
    if lower.is_empty() {
        return false;
    }
    let first = lower.split_whitespace().next().unwrap_or_default();
    let common = [
        "rg",
        "git",
        "cargo",
        "pnpm",
        "npm",
        "node",
        "python",
        "pytest",
        "pwsh",
        "powershell",
        "cmd",
        "dir",
        "ls",
        "cat",
        "type",
        "echo",
        "cd",
        "mkdir",
        "cp",
        "copy",
        "move",
        "del",
        "rm",
    ];
    common.contains(&first)
        || first.starts_with("get-")
        || first.starts_with("./")
        || first.starts_with(".\\")
        || lower.contains(" | ")
        || lower.contains(" && ")
        || lower.contains(" ; ")
}

const FILE_PATH_KEYS: [&str; 10] = [
    "path",
    "file_path",
    "filePath",
    "filepath",
    "filename",
    "file",
    "target",
    "targetFile",
    "absolutePath",
    "uri",
];

const SHELL_COMMAND_KEYS: [&str; 4] = ["command", "cmd", "script", "line"];

const WRITE_CONTENT_KEYS: [&str; 8] = [
    "content",
    "text",
    "body",
    "value",
    "markdown",
    "document",
    "output",
    "file_content",
];

const NESTED_ARGS_KEYS: [&str; 10] = [
    "arguments",
    "args",
    "input",
    "params",
    "payload",
    "data",
    "tool_input",
    "toolInput",
    "tool_args",
    "toolArgs",
];

fn tool_signature(tool_name: &str, args: &Value) -> String {
    let normalized = normalize_tool_name(tool_name);
    if normalized == "websearch" {
        let query = extract_websearch_query(args)
            .unwrap_or_default()
            .to_lowercase();
        let limit = args
            .get("limit")
            .or_else(|| args.get("numResults"))
            .or_else(|| args.get("num_results"))
            .and_then(|v| v.as_u64())
            .unwrap_or(8);
        let domains = args
            .get("domains")
            .or_else(|| args.get("domain"))
            .map(|v| v.to_string())
            .unwrap_or_default();
        let recency = args.get("recency").and_then(|v| v.as_u64()).unwrap_or(0);
        return format!("websearch:q={query}|limit={limit}|domains={domains}|recency={recency}");
    }
    format!("{}:{}", normalized, args)
}

fn stable_hash(input: &str) -> String {
    let mut hasher = DefaultHasher::new();
    input.hash(&mut hasher);
    format!("{:016x}", hasher.finish())
}

fn summarize_tool_outputs(outputs: &[String]) -> String {
    outputs
        .iter()
        .take(6)
        .map(|output| truncate_text(output, 600))
        .collect::<Vec<_>>()
        .join("\n\n")
}

fn is_os_mismatch_tool_output(output: &str) -> bool {
    let lower = output.to_ascii_lowercase();
    lower.contains("os error 3")
        || lower.contains("system cannot find the path specified")
        || lower.contains("command not found")
        || lower.contains("is not recognized as an internal or external command")
        || lower.contains("shell command blocked on windows")
}

fn tandem_runtime_system_prompt(host: &HostRuntimeContext) -> String {
    let mut sections = Vec::new();
    if os_aware_prompts_enabled() {
        sections.push(format!(
            "[Execution Environment]\nHost OS: {}\nShell: {}\nPath style: {}\nArchitecture: {}",
            host_os_label(host.os),
            shell_family_label(host.shell_family),
            path_style_label(host.path_style),
            host.arch
        ));
    }
    sections.push(
        "You are operating inside Tandem (Desktop/TUI) as an engine-backed coding assistant.
Use tool calls to inspect and modify the workspace when needed instead of asking the user
to manually run basic discovery steps. Permission prompts may occur for some tools; if
a tool is denied or blocked, explain what was blocked and suggest a concrete next step."
            .to_string(),
    );
    if host.os == HostOs::Windows {
        sections.push(
            "Windows guidance: prefer cross-platform tools (`glob`, `grep`, `read`, `write`, `edit`) and PowerShell-native commands.
Avoid Unix-only shell syntax (`ls -la`, `find ... -type f`, `cat` pipelines) unless translated.
If a shell command fails with a path/shell mismatch, immediately switch to cross-platform tools (`read`, `glob`, `grep`)."
                .to_string(),
        );
    } else {
        sections.push(
            "POSIX guidance: standard shell commands are available.
Use cross-platform tools (`glob`, `grep`, `read`) when they are simpler and safer for codebase exploration."
                .to_string(),
        );
    }
    sections.join("\n\n")
}

fn os_aware_prompts_enabled() -> bool {
    std::env::var("TANDEM_OS_AWARE_PROMPTS")
        .ok()
        .map(|v| {
            let normalized = v.trim().to_ascii_lowercase();
            !(normalized == "0" || normalized == "false" || normalized == "off")
        })
        .unwrap_or(true)
}

fn host_os_label(os: HostOs) -> &'static str {
    match os {
        HostOs::Windows => "windows",
        HostOs::Linux => "linux",
        HostOs::Macos => "macos",
    }
}

fn shell_family_label(shell: ShellFamily) -> &'static str {
    match shell {
        ShellFamily::Powershell => "powershell",
        ShellFamily::Posix => "posix",
    }
}

fn path_style_label(path_style: PathStyle) -> &'static str {
    match path_style {
        PathStyle::Windows => "windows",
        PathStyle::Posix => "posix",
    }
}

fn should_force_workspace_probe(user_text: &str, completion: &str) -> bool {
    let user = user_text.to_lowercase();
    let reply = completion.to_lowercase();

    let asked_for_project_context = [
        "what is this project",
        "what's this project",
        "what project is this",
        "explain this project",
        "analyze this project",
        "inspect this project",
        "look at the project",
        "summarize this project",
        "show me this project",
        "what files are in",
        "show files",
        "list files",
        "read files",
        "browse files",
        "use glob",
        "run glob",
    ]
    .iter()
    .any(|needle| user.contains(needle));

    if !asked_for_project_context {
        return false;
    }

    let assistant_claimed_no_access = [
        "can't inspect",
        "cannot inspect",
        "unable to inspect",
        "unable to directly inspect",
        "can't access",
        "cannot access",
        "unable to access",
        "can't read files",
        "cannot read files",
        "unable to read files",
        "tool restriction",
        "tool restrictions",
        "don't have visibility",
        "no visibility",
        "haven't been able to inspect",
        "i don't know what this project is",
        "need your help to",
        "sandbox",
        "restriction",
        "system restriction",
        "permissions restrictions",
    ]
    .iter()
    .any(|needle| reply.contains(needle));

    // If the user is explicitly asking for project inspection and the model replies with
    // a no-access narrative instead of making a tool call, force a minimal read-only probe.
    asked_for_project_context && assistant_claimed_no_access
}

fn parse_tool_invocation(input: &str) -> Option<(String, serde_json::Value)> {
    let raw = input.trim();
    if !raw.starts_with("/tool ") {
        return None;
    }
    let rest = raw.trim_start_matches("/tool ").trim();
    let mut split = rest.splitn(2, ' ');
    let tool = normalize_tool_name(split.next()?.trim());
    let args = split
        .next()
        .and_then(|v| serde_json::from_str::<serde_json::Value>(v).ok())
        .unwrap_or_else(|| json!({}));
    Some((tool, args))
}

fn parse_tool_invocations_from_response(input: &str) -> Vec<(String, serde_json::Value)> {
    let trimmed = input.trim();
    if trimmed.is_empty() {
        return Vec::new();
    }

    if let Ok(parsed) = serde_json::from_str::<serde_json::Value>(trimmed) {
        if let Some(found) = extract_tool_call_from_value(&parsed) {
            return vec![found];
        }
    }

    if let Some(block) = extract_first_json_object(trimmed) {
        if let Ok(parsed) = serde_json::from_str::<serde_json::Value>(&block) {
            if let Some(found) = extract_tool_call_from_value(&parsed) {
                return vec![found];
            }
        }
    }

    parse_function_style_tool_calls(trimmed)
}

#[cfg(test)]
fn parse_tool_invocation_from_response(input: &str) -> Option<(String, serde_json::Value)> {
    parse_tool_invocations_from_response(input)
        .into_iter()
        .next()
}

fn parse_function_style_tool_calls(input: &str) -> Vec<(String, Value)> {
    let mut calls = Vec::new();
    let lower = input.to_lowercase();
    let names = [
        "todo_write",
        "todowrite",
        "update_todo_list",
        "update_todos",
    ];
    let mut cursor = 0usize;

    while cursor < lower.len() {
        let mut best: Option<(usize, &str)> = None;
        for name in names {
            let needle = format!("{name}(");
            if let Some(rel_idx) = lower[cursor..].find(&needle) {
                let idx = cursor + rel_idx;
                if best.as_ref().is_none_or(|(best_idx, _)| idx < *best_idx) {
                    best = Some((idx, name));
                }
            }
        }

        let Some((tool_start, tool_name)) = best else {
            break;
        };

        let open_paren = tool_start + tool_name.len();
        if let Some(close_paren) = find_matching_paren(input, open_paren) {
            if let Some(args_text) = input.get(open_paren + 1..close_paren) {
                let args = parse_function_style_args(args_text.trim());
                calls.push((normalize_tool_name(tool_name), Value::Object(args)));
            }
            cursor = close_paren.saturating_add(1);
        } else {
            cursor = tool_start.saturating_add(tool_name.len());
        }
    }

    calls
}

fn find_matching_paren(input: &str, open_paren: usize) -> Option<usize> {
    if input.as_bytes().get(open_paren).copied()? != b'(' {
        return None;
    }

    let mut depth = 0usize;
    let mut in_single = false;
    let mut in_double = false;
    let mut escaped = false;

    for (offset, ch) in input.get(open_paren..)?.char_indices() {
        if escaped {
            escaped = false;
            continue;
        }
        if ch == '\\' && (in_single || in_double) {
            escaped = true;
            continue;
        }
        if ch == '\'' && !in_double {
            in_single = !in_single;
            continue;
        }
        if ch == '"' && !in_single {
            in_double = !in_double;
            continue;
        }
        if in_single || in_double {
            continue;
        }

        match ch {
            '(' => depth += 1,
            ')' => {
                depth = depth.saturating_sub(1);
                if depth == 0 {
                    return Some(open_paren + offset);
                }
            }
            _ => {}
        }
    }

    None
}

fn parse_function_style_args(input: &str) -> Map<String, Value> {
    let mut args = Map::new();
    if input.trim().is_empty() {
        return args;
    }

    let mut parts = Vec::<String>::new();
    let mut current = String::new();
    let mut in_single = false;
    let mut in_double = false;
    let mut escaped = false;
    let mut depth_paren = 0usize;
    let mut depth_bracket = 0usize;
    let mut depth_brace = 0usize;

    for ch in input.chars() {
        if escaped {
            current.push(ch);
            escaped = false;
            continue;
        }
        if ch == '\\' && (in_single || in_double) {
            current.push(ch);
            escaped = true;
            continue;
        }
        if ch == '\'' && !in_double {
            in_single = !in_single;
            current.push(ch);
            continue;
        }
        if ch == '"' && !in_single {
            in_double = !in_double;
            current.push(ch);
            continue;
        }
        if in_single || in_double {
            current.push(ch);
            continue;
        }

        match ch {
            '(' => depth_paren += 1,
            ')' => depth_paren = depth_paren.saturating_sub(1),
            '[' => depth_bracket += 1,
            ']' => depth_bracket = depth_bracket.saturating_sub(1),
            '{' => depth_brace += 1,
            '}' => depth_brace = depth_brace.saturating_sub(1),
            ',' if depth_paren == 0 && depth_bracket == 0 && depth_brace == 0 => {
                let part = current.trim();
                if !part.is_empty() {
                    parts.push(part.to_string());
                }
                current.clear();
                continue;
            }
            _ => {}
        }
        current.push(ch);
    }
    let tail = current.trim();
    if !tail.is_empty() {
        parts.push(tail.to_string());
    }

    for part in parts {
        let Some((raw_key, raw_value)) = part
            .split_once('=')
            .or_else(|| part.split_once(':'))
            .map(|(k, v)| (k.trim(), v.trim()))
        else {
            continue;
        };
        let key = raw_key.trim_matches(|c| c == '"' || c == '\'' || c == '`');
        if key.is_empty() {
            continue;
        }
        let value = parse_scalar_like_value(raw_value);
        args.insert(key.to_string(), value);
    }

    args
}

fn parse_scalar_like_value(raw: &str) -> Value {
    let trimmed = raw.trim();
    if trimmed.is_empty() {
        return Value::Null;
    }

    if (trimmed.starts_with('"') && trimmed.ends_with('"'))
        || (trimmed.starts_with('\'') && trimmed.ends_with('\''))
    {
        return Value::String(trimmed[1..trimmed.len().saturating_sub(1)].to_string());
    }

    if trimmed.eq_ignore_ascii_case("true") {
        return Value::Bool(true);
    }
    if trimmed.eq_ignore_ascii_case("false") {
        return Value::Bool(false);
    }
    if trimmed.eq_ignore_ascii_case("null") {
        return Value::Null;
    }

    if let Ok(v) = serde_json::from_str::<Value>(trimmed) {
        return v;
    }
    if let Ok(v) = trimmed.parse::<i64>() {
        return Value::Number(Number::from(v));
    }
    if let Ok(v) = trimmed.parse::<f64>() {
        if let Some(n) = Number::from_f64(v) {
            return Value::Number(n);
        }
    }

    Value::String(trimmed.to_string())
}

fn normalize_todo_write_args(args: Value, completion: &str) -> Value {
    if is_todo_status_update_args(&args) {
        return args;
    }

    let mut obj = match args {
        Value::Object(map) => map,
        Value::Array(items) => {
            return json!({ "todos": normalize_todo_arg_items(items) });
        }
        Value::String(text) => {
            let derived = extract_todo_candidates_from_text(&text);
            if !derived.is_empty() {
                return json!({ "todos": derived });
            }
            return json!({});
        }
        _ => return json!({}),
    };

    if obj
        .get("todos")
        .and_then(|v| v.as_array())
        .map(|arr| !arr.is_empty())
        .unwrap_or(false)
    {
        return Value::Object(obj);
    }

    for alias in ["tasks", "items", "list", "checklist"] {
        if let Some(items) = obj.get(alias).and_then(|v| v.as_array()) {
            let normalized = normalize_todo_arg_items(items.clone());
            if !normalized.is_empty() {
                obj.insert("todos".to_string(), Value::Array(normalized));
                return Value::Object(obj);
            }
        }
    }

    let derived = extract_todo_candidates_from_text(completion);
    if !derived.is_empty() {
        obj.insert("todos".to_string(), Value::Array(derived));
    }
    Value::Object(obj)
}

fn normalize_todo_arg_items(items: Vec<Value>) -> Vec<Value> {
    items
        .into_iter()
        .filter_map(|item| match item {
            Value::String(text) => {
                let content = text.trim();
                if content.is_empty() {
                    None
                } else {
                    Some(json!({"content": content}))
                }
            }
            Value::Object(mut obj) => {
                if !obj.contains_key("content") {
                    if let Some(text) = obj.get("text").cloned() {
                        obj.insert("content".to_string(), text);
                    } else if let Some(title) = obj.get("title").cloned() {
                        obj.insert("content".to_string(), title);
                    } else if let Some(name) = obj.get("name").cloned() {
                        obj.insert("content".to_string(), name);
                    }
                }
                let content = obj
                    .get("content")
                    .and_then(|v| v.as_str())
                    .map(str::trim)
                    .unwrap_or("");
                if content.is_empty() {
                    None
                } else {
                    Some(Value::Object(obj))
                }
            }
            _ => None,
        })
        .collect()
}

fn is_todo_status_update_args(args: &Value) -> bool {
    let Some(obj) = args.as_object() else {
        return false;
    };
    let has_status = obj
        .get("status")
        .and_then(|v| v.as_str())
        .map(|s| !s.trim().is_empty())
        .unwrap_or(false);
    let has_target =
        obj.get("task_id").is_some() || obj.get("todo_id").is_some() || obj.get("id").is_some();
    has_status && has_target
}

fn is_empty_todo_write_args(args: &Value) -> bool {
    if is_todo_status_update_args(args) {
        return false;
    }
    let Some(obj) = args.as_object() else {
        return true;
    };
    !obj.get("todos")
        .and_then(|v| v.as_array())
        .map(|arr| !arr.is_empty())
        .unwrap_or(false)
}

fn parse_streamed_tool_args(tool_name: &str, raw_args: &str) -> Value {
    let trimmed = raw_args.trim();
    if trimmed.is_empty() {
        return json!({});
    }

    if let Ok(parsed) = serde_json::from_str::<Value>(trimmed) {
        return normalize_streamed_tool_args(tool_name, parsed, trimmed);
    }

    // Some providers emit non-JSON argument text (for example: raw query strings
    // or key=value fragments). Recover the common forms instead of dropping to {}.
    let kv_args = parse_function_style_args(trimmed);
    if !kv_args.is_empty() {
        return normalize_streamed_tool_args(tool_name, Value::Object(kv_args), trimmed);
    }

    if normalize_tool_name(tool_name) == "websearch" {
        return json!({ "query": trimmed });
    }

    json!({})
}

fn normalize_streamed_tool_args(tool_name: &str, parsed: Value, raw: &str) -> Value {
    let normalized_tool = normalize_tool_name(tool_name);
    if normalized_tool != "websearch" {
        return parsed;
    }

    match parsed {
        Value::Object(mut obj) => {
            if !has_websearch_query(&obj) && !raw.trim().is_empty() {
                obj.insert("query".to_string(), Value::String(raw.trim().to_string()));
            }
            Value::Object(obj)
        }
        Value::String(s) => {
            let q = s.trim();
            if q.is_empty() {
                json!({})
            } else {
                json!({ "query": q })
            }
        }
        other => other,
    }
}

fn has_websearch_query(obj: &Map<String, Value>) -> bool {
    const QUERY_KEYS: [&str; 5] = ["query", "q", "search_query", "searchQuery", "keywords"];
    QUERY_KEYS.iter().any(|key| {
        obj.get(*key)
            .and_then(|v| v.as_str())
            .map(|s| !s.trim().is_empty())
            .unwrap_or(false)
    })
}

fn extract_tool_call_from_value(value: &Value) -> Option<(String, Value)> {
    if let Some(obj) = value.as_object() {
        if let Some(tool) = obj.get("tool").and_then(|v| v.as_str()) {
            return Some((
                normalize_tool_name(tool),
                obj.get("args").cloned().unwrap_or_else(|| json!({})),
            ));
        }

        if let Some(tool) = obj.get("name").and_then(|v| v.as_str()) {
            let args = obj
                .get("args")
                .cloned()
                .or_else(|| obj.get("arguments").cloned())
                .unwrap_or_else(|| json!({}));
            let normalized_tool = normalize_tool_name(tool);
            let args = if let Some(raw) = args.as_str() {
                parse_streamed_tool_args(&normalized_tool, raw)
            } else {
                args
            };
            return Some((normalized_tool, args));
        }

        for key in [
            "tool_call",
            "toolCall",
            "call",
            "function_call",
            "functionCall",
        ] {
            if let Some(nested) = obj.get(key) {
                if let Some(found) = extract_tool_call_from_value(nested) {
                    return Some(found);
                }
            }
        }
    }

    if let Some(items) = value.as_array() {
        for item in items {
            if let Some(found) = extract_tool_call_from_value(item) {
                return Some(found);
            }
        }
    }

    None
}

fn extract_first_json_object(input: &str) -> Option<String> {
    let mut start = None;
    let mut depth = 0usize;
    for (idx, ch) in input.char_indices() {
        if ch == '{' {
            if start.is_none() {
                start = Some(idx);
            }
            depth += 1;
        } else if ch == '}' {
            if depth == 0 {
                continue;
            }
            depth -= 1;
            if depth == 0 {
                let begin = start?;
                let block = input.get(begin..=idx)?;
                return Some(block.to_string());
            }
        }
    }
    None
}

fn extract_todo_candidates_from_text(input: &str) -> Vec<Value> {
    let mut seen = HashSet::<String>::new();
    let mut todos = Vec::new();

    for raw_line in input.lines() {
        let mut line = raw_line.trim();
        let mut structured_line = false;
        if line.is_empty() {
            continue;
        }
        if line.starts_with("```") {
            continue;
        }
        if line.ends_with(':') {
            continue;
        }
        if let Some(rest) = line
            .strip_prefix("- [ ]")
            .or_else(|| line.strip_prefix("* [ ]"))
            .or_else(|| line.strip_prefix("- [x]"))
            .or_else(|| line.strip_prefix("* [x]"))
        {
            line = rest.trim();
            structured_line = true;
        } else if let Some(rest) = line.strip_prefix("- ").or_else(|| line.strip_prefix("* ")) {
            line = rest.trim();
            structured_line = true;
        } else {
            let bytes = line.as_bytes();
            let mut i = 0usize;
            while i < bytes.len() && bytes[i].is_ascii_digit() {
                i += 1;
            }
            if i > 0 && i + 1 < bytes.len() && (bytes[i] == b'.' || bytes[i] == b')') {
                line = line[i + 1..].trim();
                structured_line = true;
            }
        }
        if !structured_line {
            continue;
        }

        let content = line.trim_matches(|c: char| c.is_whitespace() || c == '-' || c == '*');
        if content.len() < 5 || content.len() > 180 {
            continue;
        }
        let key = content.to_lowercase();
        if seen.contains(&key) {
            continue;
        }
        seen.insert(key);
        todos.push(json!({ "content": content }));
        if todos.len() >= 25 {
            break;
        }
    }

    todos
}

async fn emit_plan_todo_fallback(
    storage: std::sync::Arc<Storage>,
    bus: &EventBus,
    session_id: &str,
    message_id: &str,
    completion: &str,
) {
    let todos = extract_todo_candidates_from_text(completion);
    if todos.is_empty() {
        return;
    }

    let invoke_part = WireMessagePart::tool_invocation(
        session_id,
        message_id,
        "todo_write",
        json!({"todos": todos.clone()}),
    );
    let call_id = invoke_part.id.clone();
    bus.publish(EngineEvent::new(
        "message.part.updated",
        json!({"part": invoke_part}),
    ));

    if storage.set_todos(session_id, todos).await.is_err() {
        let mut failed_part =
            WireMessagePart::tool_result(session_id, message_id, "todo_write", json!(null));
        failed_part.id = call_id;
        failed_part.state = Some("failed".to_string());
        failed_part.error = Some("failed to persist plan todos".to_string());
        bus.publish(EngineEvent::new(
            "message.part.updated",
            json!({"part": failed_part}),
        ));
        return;
    }

    let normalized = storage.get_todos(session_id).await;
    let mut result_part = WireMessagePart::tool_result(
        session_id,
        message_id,
        "todo_write",
        json!({ "todos": normalized }),
    );
    result_part.id = call_id;
    bus.publish(EngineEvent::new(
        "message.part.updated",
        json!({"part": result_part}),
    ));
    bus.publish(EngineEvent::new(
        "todo.updated",
        json!({
            "sessionID": session_id,
            "todos": normalized
        }),
    ));
}

async fn emit_plan_question_fallback(
    storage: std::sync::Arc<Storage>,
    bus: &EventBus,
    session_id: &str,
    message_id: &str,
    completion: &str,
) {
    let trimmed = completion.trim();
    if trimmed.is_empty() {
        return;
    }

    let hints = extract_todo_candidates_from_text(trimmed)
        .into_iter()
        .take(6)
        .filter_map(|v| {
            v.get("content")
                .and_then(|c| c.as_str())
                .map(ToString::to_string)
        })
        .collect::<Vec<_>>();

    let mut options = hints
        .iter()
        .map(|label| json!({"label": label, "description": "Use this as a starting task"}))
        .collect::<Vec<_>>();
    if options.is_empty() {
        options = vec![
            json!({"label":"Define scope", "description":"Clarify the intended outcome"}),
            json!({"label":"Provide constraints", "description":"Budget, timeline, and constraints"}),
            json!({"label":"Draft a starter list", "description":"Generate a first-pass task list"}),
        ];
    }

    let question_payload = vec![json!({
        "header":"Planning Input",
        "question":"I couldn't produce a concrete task list yet. Which tasks should I include first?",
        "options": options,
        "multiple": true,
        "custom": true
    })];

    let request = storage
        .add_question_request(session_id, message_id, question_payload.clone())
        .await
        .ok();
    bus.publish(EngineEvent::new(
        "question.asked",
        json!({
            "id": request
                .as_ref()
                .map(|req| req.id.clone())
                .unwrap_or_else(|| format!("q-{}", uuid::Uuid::new_v4())),
            "sessionID": session_id,
            "messageID": message_id,
            "questions": question_payload,
            "tool": request.and_then(|req| {
                req.tool.map(|tool| {
                    json!({
                        "callID": tool.call_id,
                        "messageID": tool.message_id
                    })
                })
            })
        }),
    ));
}

async fn load_chat_history(storage: std::sync::Arc<Storage>, session_id: &str) -> Vec<ChatMessage> {
    let Some(session) = storage.get_session(session_id).await else {
        return Vec::new();
    };
    let messages = session
        .messages
        .into_iter()
        .map(|m| {
            let role = format!("{:?}", m.role).to_lowercase();
            let content = m
                .parts
                .into_iter()
                .map(|part| match part {
                    MessagePart::Text { text } => text,
                    MessagePart::Reasoning { text } => text,
                    MessagePart::ToolInvocation { tool, result, .. } => {
                        format!("Tool {tool} => {}", result.unwrap_or_else(|| json!({})))
                    }
                })
                .collect::<Vec<_>>()
                .join("\n");
            ChatMessage { role, content }
        })
        .collect::<Vec<_>>();
    compact_chat_history(messages)
}

async fn emit_tool_side_events(
    storage: std::sync::Arc<Storage>,
    bus: &EventBus,
    session_id: &str,
    message_id: &str,
    tool: &str,
    args: &serde_json::Value,
    metadata: &serde_json::Value,
    workspace_root: Option<&str>,
    effective_cwd: Option<&str>,
) {
    if tool == "todo_write" {
        let todos_from_metadata = metadata
            .get("todos")
            .and_then(|v| v.as_array())
            .cloned()
            .unwrap_or_default();

        if !todos_from_metadata.is_empty() {
            let _ = storage.set_todos(session_id, todos_from_metadata).await;
        } else {
            let current = storage.get_todos(session_id).await;
            if let Some(updated) = apply_todo_updates_from_args(current, args) {
                let _ = storage.set_todos(session_id, updated).await;
            }
        }

        let normalized = storage.get_todos(session_id).await;
        bus.publish(EngineEvent::new(
            "todo.updated",
            json!({
                "sessionID": session_id,
                "todos": normalized,
                "workspaceRoot": workspace_root,
                "effectiveCwd": effective_cwd
            }),
        ));
    }
    if tool == "question" {
        let questions = metadata
            .get("questions")
            .and_then(|v| v.as_array())
            .cloned()
            .unwrap_or_default();
        let request = storage
            .add_question_request(session_id, message_id, questions.clone())
            .await
            .ok();
        bus.publish(EngineEvent::new(
            "question.asked",
            json!({
                "id": request
                    .as_ref()
                    .map(|req| req.id.clone())
                    .unwrap_or_else(|| format!("q-{}", uuid::Uuid::new_v4())),
                "sessionID": session_id,
                "messageID": message_id,
                "questions": questions,
                "tool": request.and_then(|req| {
                    req.tool.map(|tool| {
                        json!({
                            "callID": tool.call_id,
                            "messageID": tool.message_id
                        })
                    })
                }),
                "workspaceRoot": workspace_root,
                "effectiveCwd": effective_cwd
            }),
        ));
    }
}

fn apply_todo_updates_from_args(current: Vec<Value>, args: &Value) -> Option<Vec<Value>> {
    let obj = args.as_object()?;
    let mut todos = current;
    let mut changed = false;

    if let Some(items) = obj.get("todos").and_then(|v| v.as_array()) {
        for item in items {
            let Some(item_obj) = item.as_object() else {
                continue;
            };
            let status = item_obj
                .get("status")
                .and_then(|v| v.as_str())
                .map(normalize_todo_status);
            let target = item_obj
                .get("task_id")
                .or_else(|| item_obj.get("todo_id"))
                .or_else(|| item_obj.get("id"));

            if let (Some(status), Some(target)) = (status, target) {
                changed |= apply_single_todo_status_update(&mut todos, target, &status);
            }
        }
    }

    let status = obj
        .get("status")
        .and_then(|v| v.as_str())
        .map(normalize_todo_status);
    let target = obj
        .get("task_id")
        .or_else(|| obj.get("todo_id"))
        .or_else(|| obj.get("id"));
    if let (Some(status), Some(target)) = (status, target) {
        changed |= apply_single_todo_status_update(&mut todos, target, &status);
    }

    if changed {
        Some(todos)
    } else {
        None
    }
}

fn apply_single_todo_status_update(todos: &mut [Value], target: &Value, status: &str) -> bool {
    let idx_from_value = match target {
        Value::Number(n) => n.as_u64().map(|v| v.saturating_sub(1) as usize),
        Value::String(s) => {
            let trimmed = s.trim();
            trimmed
                .parse::<usize>()
                .ok()
                .map(|v| v.saturating_sub(1))
                .or_else(|| {
                    let digits = trimmed
                        .chars()
                        .rev()
                        .take_while(|c| c.is_ascii_digit())
                        .collect::<String>()
                        .chars()
                        .rev()
                        .collect::<String>();
                    digits.parse::<usize>().ok().map(|v| v.saturating_sub(1))
                })
        }
        _ => None,
    };

    if let Some(idx) = idx_from_value {
        if idx < todos.len() {
            if let Some(obj) = todos[idx].as_object_mut() {
                obj.insert("status".to_string(), Value::String(status.to_string()));
                return true;
            }
        }
    }

    let id_target = target.as_str().map(|s| s.trim()).filter(|s| !s.is_empty());
    if let Some(id_target) = id_target {
        for todo in todos.iter_mut() {
            if let Some(obj) = todo.as_object_mut() {
                if obj.get("id").and_then(|v| v.as_str()) == Some(id_target) {
                    obj.insert("status".to_string(), Value::String(status.to_string()));
                    return true;
                }
            }
        }
    }

    false
}

fn normalize_todo_status(raw: &str) -> String {
    match raw.trim().to_lowercase().as_str() {
        "in_progress" | "inprogress" | "running" | "working" => "in_progress".to_string(),
        "done" | "complete" | "completed" => "completed".to_string(),
        "cancelled" | "canceled" | "aborted" | "skipped" => "cancelled".to_string(),
        "open" | "todo" | "pending" => "pending".to_string(),
        other => other.to_string(),
    }
}

fn compact_chat_history(messages: Vec<ChatMessage>) -> Vec<ChatMessage> {
    const MAX_CONTEXT_CHARS: usize = 80_000;
    const KEEP_RECENT_MESSAGES: usize = 40;

    if messages.len() <= KEEP_RECENT_MESSAGES {
        let total_chars = messages.iter().map(|m| m.content.len()).sum::<usize>();
        if total_chars <= MAX_CONTEXT_CHARS {
            return messages;
        }
    }

    let mut kept = messages;
    let mut dropped_count = 0usize;
    let mut total_chars = kept.iter().map(|m| m.content.len()).sum::<usize>();

    while kept.len() > KEEP_RECENT_MESSAGES || total_chars > MAX_CONTEXT_CHARS {
        if kept.is_empty() {
            break;
        }
        let removed = kept.remove(0);
        total_chars = total_chars.saturating_sub(removed.content.len());
        dropped_count += 1;
    }

    if dropped_count > 0 {
        kept.insert(
            0,
            ChatMessage {
                role: "system".to_string(),
                content: format!(
                    "[history compacted: omitted {} older messages to fit context window]",
                    dropped_count
                ),
            },
        );
    }
    kept
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{EventBus, Storage};
    use uuid::Uuid;

    #[tokio::test]
    async fn todo_updated_event_is_normalized() {
        let base = std::env::temp_dir().join(format!("engine-loop-test-{}", Uuid::new_v4()));
        let storage = std::sync::Arc::new(Storage::new(&base).await.expect("storage"));
        let session = tandem_types::Session::new(Some("s".to_string()), Some(".".to_string()));
        let session_id = session.id.clone();
        storage.save_session(session).await.expect("save session");

        let bus = EventBus::new();
        let mut rx = bus.subscribe();
        emit_tool_side_events(
            storage.clone(),
            &bus,
            &session_id,
            "m1",
            "todo_write",
            &json!({"todos":[{"content":"ship parity"}]}),
            &json!({"todos":[{"content":"ship parity"}]}),
            Some("."),
            Some("."),
        )
        .await;

        let event = rx.recv().await.expect("event");
        assert_eq!(event.event_type, "todo.updated");
        let todos = event
            .properties
            .get("todos")
            .and_then(|v| v.as_array())
            .cloned()
            .unwrap_or_default();
        assert_eq!(todos.len(), 1);
        assert!(todos[0].get("id").and_then(|v| v.as_str()).is_some());
        assert_eq!(
            todos[0].get("content").and_then(|v| v.as_str()),
            Some("ship parity")
        );
        assert!(todos[0].get("status").and_then(|v| v.as_str()).is_some());
    }

    #[tokio::test]
    async fn question_asked_event_contains_tool_reference() {
        let base = std::env::temp_dir().join(format!("engine-loop-test-{}", Uuid::new_v4()));
        let storage = std::sync::Arc::new(Storage::new(&base).await.expect("storage"));
        let session = tandem_types::Session::new(Some("s".to_string()), Some(".".to_string()));
        let session_id = session.id.clone();
        storage.save_session(session).await.expect("save session");

        let bus = EventBus::new();
        let mut rx = bus.subscribe();
        emit_tool_side_events(
            storage,
            &bus,
            &session_id,
            "msg-1",
            "question",
            &json!({"questions":[{"header":"Topic","question":"Pick one","options":[{"label":"A","description":"d"}]}]}),
            &json!({"questions":[{"header":"Topic","question":"Pick one","options":[{"label":"A","description":"d"}]}]}),
            Some("."),
            Some("."),
        )
        .await;

        let event = rx.recv().await.expect("event");
        assert_eq!(event.event_type, "question.asked");
        assert_eq!(
            event
                .properties
                .get("sessionID")
                .and_then(|v| v.as_str())
                .unwrap_or(""),
            session_id
        );
        let tool = event
            .properties
            .get("tool")
            .cloned()
            .unwrap_or_else(|| json!({}));
        assert!(tool.get("callID").and_then(|v| v.as_str()).is_some());
        assert_eq!(
            tool.get("messageID").and_then(|v| v.as_str()),
            Some("msg-1")
        );
    }

    #[test]
    fn compact_chat_history_keeps_recent_and_inserts_summary() {
        let mut messages = Vec::new();
        for i in 0..60 {
            messages.push(ChatMessage {
                role: "user".to_string(),
                content: format!("message-{i}"),
            });
        }
        let compacted = compact_chat_history(messages);
        assert!(compacted.len() <= 41);
        assert_eq!(compacted[0].role, "system");
        assert!(compacted[0].content.contains("history compacted"));
        assert!(compacted.iter().any(|m| m.content.contains("message-59")));
    }

    #[test]
    fn extracts_todos_from_checklist_and_numbered_lines() {
        let input = r#"
Plan:
- [ ] Audit current implementation
- [ ] Add planner fallback
1. Add regression test coverage
"#;
        let todos = extract_todo_candidates_from_text(input);
        assert_eq!(todos.len(), 3);
        assert_eq!(
            todos[0].get("content").and_then(|v| v.as_str()),
            Some("Audit current implementation")
        );
    }

    #[test]
    fn does_not_extract_todos_from_plain_prose_lines() {
        let input = r#"
I need more information to proceed.
Can you tell me the event size and budget?
Once I have that, I can provide a detailed plan.
"#;
        let todos = extract_todo_candidates_from_text(input);
        assert!(todos.is_empty());
    }

    #[test]
    fn parses_wrapped_tool_call_from_markdown_response() {
        let input = r#"
Here is the tool call:
```json
{"tool_call":{"name":"todo_write","arguments":{"todos":[{"content":"a"}]}}}
```
"#;
        let parsed = parse_tool_invocation_from_response(input).expect("tool call");
        assert_eq!(parsed.0, "todo_write");
        assert!(parsed.1.get("todos").is_some());
    }

    #[test]
    fn parses_function_style_todowrite_call() {
        let input = r#"Status: Completed
Call: todowrite(task_id=2, status="completed")"#;
        let parsed = parse_tool_invocation_from_response(input).expect("function-style tool call");
        assert_eq!(parsed.0, "todo_write");
        assert_eq!(parsed.1.get("task_id").and_then(|v| v.as_i64()), Some(2));
        assert_eq!(
            parsed.1.get("status").and_then(|v| v.as_str()),
            Some("completed")
        );
    }

    #[test]
    fn parses_multiple_function_style_todowrite_calls() {
        let input = r#"
Call: todowrite(task_id=2, status="completed")
Call: todowrite(task_id=3, status="in_progress")
"#;
        let parsed = parse_tool_invocations_from_response(input);
        assert_eq!(parsed.len(), 2);
        assert_eq!(parsed[0].0, "todo_write");
        assert_eq!(parsed[0].1.get("task_id").and_then(|v| v.as_i64()), Some(2));
        assert_eq!(
            parsed[0].1.get("status").and_then(|v| v.as_str()),
            Some("completed")
        );
        assert_eq!(parsed[1].1.get("task_id").and_then(|v| v.as_i64()), Some(3));
        assert_eq!(
            parsed[1].1.get("status").and_then(|v| v.as_str()),
            Some("in_progress")
        );
    }

    #[test]
    fn applies_todo_status_update_from_task_id_args() {
        let current = vec![
            json!({"id":"todo-1","content":"a","status":"pending"}),
            json!({"id":"todo-2","content":"b","status":"pending"}),
            json!({"id":"todo-3","content":"c","status":"pending"}),
        ];
        let updated =
            apply_todo_updates_from_args(current, &json!({"task_id":2, "status":"completed"}))
                .expect("status update");
        assert_eq!(
            updated[1].get("status").and_then(|v| v.as_str()),
            Some("completed")
        );
    }

    #[test]
    fn normalizes_todo_write_tasks_alias() {
        let normalized = normalize_todo_write_args(
            json!({"tasks":[{"title":"Book venue"},{"name":"Send invites"}]}),
            "",
        );
        let todos = normalized
            .get("todos")
            .and_then(|v| v.as_array())
            .cloned()
            .unwrap_or_default();
        assert_eq!(todos.len(), 2);
        assert_eq!(
            todos[0].get("content").and_then(|v| v.as_str()),
            Some("Book venue")
        );
        assert_eq!(
            todos[1].get("content").and_then(|v| v.as_str()),
            Some("Send invites")
        );
    }

    #[test]
    fn normalizes_todo_write_from_completion_when_args_empty() {
        let completion = "Plan:\n1. Secure venue\n2. Create playlist\n3. Send invites";
        let normalized = normalize_todo_write_args(json!({}), completion);
        let todos = normalized
            .get("todos")
            .and_then(|v| v.as_array())
            .cloned()
            .unwrap_or_default();
        assert_eq!(todos.len(), 3);
        assert!(!is_empty_todo_write_args(&normalized));
    }

    #[test]
    fn empty_todo_write_args_allows_status_updates() {
        let args = json!({"task_id": 2, "status":"completed"});
        assert!(!is_empty_todo_write_args(&args));
    }

    #[test]
    fn streamed_websearch_args_fallback_to_query_string() {
        let parsed = parse_streamed_tool_args("websearch", "meaning of life");
        assert_eq!(
            parsed.get("query").and_then(|v| v.as_str()),
            Some("meaning of life")
        );
    }

    #[test]
    fn streamed_websearch_stringified_json_args_are_unwrapped() {
        let parsed = parse_streamed_tool_args("websearch", r#""donkey gestation period""#);
        assert_eq!(
            parsed.get("query").and_then(|v| v.as_str()),
            Some("donkey gestation period")
        );
    }

    #[test]
    fn normalize_tool_args_websearch_infers_from_user_text() {
        let normalized =
            normalize_tool_args("websearch", json!({}), "web search meaning of life", "");
        assert_eq!(
            normalized.args.get("query").and_then(|v| v.as_str()),
            Some("meaning of life")
        );
        assert_eq!(normalized.args_source, "inferred_from_user");
        assert_eq!(normalized.args_integrity, "recovered");
    }

    #[test]
    fn normalize_tool_args_websearch_keeps_existing_query() {
        let normalized = normalize_tool_args(
            "websearch",
            json!({"query":"already set"}),
            "web search should not override",
            "",
        );
        assert_eq!(
            normalized.args.get("query").and_then(|v| v.as_str()),
            Some("already set")
        );
        assert_eq!(normalized.args_source, "provider_json");
        assert_eq!(normalized.args_integrity, "ok");
    }

    #[test]
    fn normalize_tool_args_websearch_fails_when_unrecoverable() {
        let normalized = normalize_tool_args("websearch", json!({}), "search", "");
        assert!(normalized.query.is_none());
        assert!(normalized.missing_terminal);
        assert_eq!(normalized.args_source, "missing");
        assert_eq!(normalized.args_integrity, "empty");
    }

    #[test]
    fn normalize_tool_args_write_requires_path() {
        let normalized = normalize_tool_args("write", json!({}), "", "");
        assert!(normalized.missing_terminal);
        assert_eq!(
            normalized.missing_terminal_reason.as_deref(),
            Some("FILE_PATH_MISSING")
        );
    }

    #[test]
    fn normalize_tool_args_write_recovers_alias_path_key() {
        let normalized = normalize_tool_args(
            "write",
            json!({"filePath":"docs/CONCEPT.md","content":"hello"}),
            "",
            "",
        );
        assert!(!normalized.missing_terminal);
        assert_eq!(
            normalized.args.get("path").and_then(|v| v.as_str()),
            Some("docs/CONCEPT.md")
        );
        assert_eq!(
            normalized.args.get("content").and_then(|v| v.as_str()),
            Some("hello")
        );
    }

    #[test]
    fn normalize_tool_args_read_infers_path_from_user_prompt() {
        let normalized = normalize_tool_args(
            "read",
            json!({}),
            "Please inspect `FEATURE_LIST.md` and summarize key sections.",
            "",
        );
        assert!(!normalized.missing_terminal);
        assert_eq!(
            normalized.args.get("path").and_then(|v| v.as_str()),
            Some("FEATURE_LIST.md")
        );
        assert_eq!(normalized.args_source, "inferred_from_user");
        assert_eq!(normalized.args_integrity, "recovered");
    }

    #[test]
    fn normalize_tool_args_read_infers_path_from_assistant_context() {
        let normalized = normalize_tool_args(
            "read",
            json!({}),
            "generic instruction",
            "I will read src-tauri/src/orchestrator/engine.rs first.",
        );
        assert!(!normalized.missing_terminal);
        assert_eq!(
            normalized.args.get("path").and_then(|v| v.as_str()),
            Some("src-tauri/src/orchestrator/engine.rs")
        );
        assert_eq!(normalized.args_source, "inferred_from_context");
        assert_eq!(normalized.args_integrity, "recovered");
    }

    #[test]
    fn normalize_tool_args_write_recovers_path_from_nested_array_payload() {
        let normalized = normalize_tool_args(
            "write",
            json!({"args":[{"file_path":"docs/CONCEPT.md"}],"content":"hello"}),
            "",
            "",
        );
        assert!(!normalized.missing_terminal);
        assert_eq!(
            normalized.args.get("path").and_then(|v| v.as_str()),
            Some("docs/CONCEPT.md")
        );
    }

    #[test]
    fn normalize_tool_args_write_recovers_content_alias() {
        let normalized = normalize_tool_args(
            "write",
            json!({"path":"docs/FEATURES.md","body":"feature notes"}),
            "",
            "",
        );
        assert!(!normalized.missing_terminal);
        assert_eq!(
            normalized.args.get("content").and_then(|v| v.as_str()),
            Some("feature notes")
        );
    }

    #[test]
    fn normalize_tool_args_write_fails_when_content_missing() {
        let normalized = normalize_tool_args("write", json!({"path":"docs/FEATURES.md"}), "", "");
        assert!(normalized.missing_terminal);
        assert_eq!(
            normalized.missing_terminal_reason.as_deref(),
            Some("WRITE_CONTENT_MISSING")
        );
    }

    #[test]
    fn normalize_tool_args_write_recovers_raw_nested_string_content() {
        let normalized = normalize_tool_args(
            "write",
            json!({"path":"docs/FEATURES.md","args":"Line 1\nLine 2"}),
            "",
            "",
        );
        assert!(!normalized.missing_terminal);
        assert_eq!(
            normalized.args.get("path").and_then(|v| v.as_str()),
            Some("docs/FEATURES.md")
        );
        assert_eq!(
            normalized.args.get("content").and_then(|v| v.as_str()),
            Some("Line 1\nLine 2")
        );
    }

    #[test]
    fn normalize_tool_args_write_does_not_treat_path_as_content() {
        let normalized = normalize_tool_args("write", json!("docs/FEATURES.md"), "", "");
        assert!(normalized.missing_terminal);
        assert_eq!(
            normalized.missing_terminal_reason.as_deref(),
            Some("WRITE_CONTENT_MISSING")
        );
    }

    #[test]
    fn normalize_tool_args_read_infers_path_from_bold_markdown() {
        let normalized = normalize_tool_args(
            "read",
            json!({}),
            "Please read **FEATURE_LIST.md** and summarize.",
            "",
        );
        assert!(!normalized.missing_terminal);
        assert_eq!(
            normalized.args.get("path").and_then(|v| v.as_str()),
            Some("FEATURE_LIST.md")
        );
    }

    #[test]
    fn normalize_tool_args_shell_infers_command_from_user_prompt() {
        let normalized = normalize_tool_args("bash", json!({}), "Run `rg -n \"TODO\" .`", "");
        assert!(!normalized.missing_terminal);
        assert_eq!(
            normalized.args.get("command").and_then(|v| v.as_str()),
            Some("rg -n \"TODO\" .")
        );
        assert_eq!(normalized.args_source, "inferred_from_user");
        assert_eq!(normalized.args_integrity, "recovered");
    }

    #[test]
    fn normalize_tool_args_read_rejects_root_only_path() {
        let normalized = normalize_tool_args("read", json!({"path":"/"}), "", "");
        assert!(normalized.missing_terminal);
        assert_eq!(
            normalized.missing_terminal_reason.as_deref(),
            Some("FILE_PATH_MISSING")
        );
    }

    #[test]
    fn normalize_tool_args_read_recovers_when_provider_path_is_root_only() {
        let normalized =
            normalize_tool_args("read", json!({"path":"/"}), "Please open `CONCEPT.md`", "");
        assert!(!normalized.missing_terminal);
        assert_eq!(
            normalized.args.get("path").and_then(|v| v.as_str()),
            Some("CONCEPT.md")
        );
        assert_eq!(normalized.args_source, "inferred_from_user");
        assert_eq!(normalized.args_integrity, "recovered");
    }

    #[test]
    fn normalize_tool_args_read_rejects_tool_call_markup_path() {
        let normalized = normalize_tool_args(
            "read",
            json!({
                "path":"<tool_call>\n<function=glob>\n<parameter=pattern>**/*</parameter>\n</function>\n</tool_call>"
            }),
            "",
            "",
        );
        assert!(normalized.missing_terminal);
        assert_eq!(
            normalized.missing_terminal_reason.as_deref(),
            Some("FILE_PATH_MISSING")
        );
    }

    #[test]
    fn normalize_tool_args_read_rejects_glob_pattern_path() {
        let normalized = normalize_tool_args("read", json!({"path":"**/*"}), "", "");
        assert!(normalized.missing_terminal);
        assert_eq!(
            normalized.missing_terminal_reason.as_deref(),
            Some("FILE_PATH_MISSING")
        );
    }

    #[test]
    fn normalize_tool_name_strips_default_api_namespace() {
        assert_eq!(normalize_tool_name("default_api:read"), "read");
        assert_eq!(normalize_tool_name("functions.shell"), "bash");
    }

    #[test]
    fn batch_helpers_use_name_when_tool_is_wrapper() {
        let args = json!({
            "tool_calls":[
                {"tool":"default_api","name":"read","args":{"path":"CONCEPT.md"}},
                {"tool":"default_api:glob","args":{"pattern":"*.md"}}
            ]
        });
        let calls = extract_batch_calls(&args);
        assert_eq!(calls.len(), 2);
        assert_eq!(calls[0].0, "read");
        assert_eq!(calls[1].0, "glob");
        assert!(is_read_only_batch_call(&args));
        let sig = batch_tool_signature(&args).unwrap_or_default();
        assert!(sig.contains("read:"));
        assert!(sig.contains("glob:"));
    }

    #[test]
    fn batch_helpers_resolve_nested_function_name() {
        let args = json!({
            "tool_calls":[
                {"tool":"default_api","function":{"name":"read"},"args":{"path":"CONCEPT.md"}}
            ]
        });
        let calls = extract_batch_calls(&args);
        assert_eq!(calls.len(), 1);
        assert_eq!(calls[0].0, "read");
        assert!(is_read_only_batch_call(&args));
    }

    #[test]
    fn batch_output_classifier_detects_non_productive_unknown_results() {
        let output = r#"
[
  {"tool":"default_api","output":"Unknown tool: default_api","metadata":{}},
  {"tool":"default_api","output":"Unknown tool: default_api","metadata":{}}
]
"#;
        assert!(is_non_productive_batch_output(output));
    }

    #[test]
    fn runtime_prompt_includes_execution_environment_block() {
        let prompt = tandem_runtime_system_prompt(&HostRuntimeContext {
            os: HostOs::Windows,
            arch: "x86_64".to_string(),
            shell_family: ShellFamily::Powershell,
            path_style: PathStyle::Windows,
        });
        assert!(prompt.contains("[Execution Environment]"));
        assert!(prompt.contains("Host OS: windows"));
        assert!(prompt.contains("Shell: powershell"));
        assert!(prompt.contains("Path style: windows"));
    }
}