use std::collections::BTreeMap;
use std::sync::Arc;
use std::sync::atomic::Ordering;
use std::time::Duration;

use crate::function_tool::FunctionCallError;
use crate::function_tool::OrCancelToolExt;
use crate::hook_runtime::PreToolUseHookResult;
use crate::hook_runtime::record_additional_contexts;
use crate::hook_runtime::run_post_tool_use_hooks;
use crate::hook_runtime::run_pre_tool_use_hooks;
use crate::memory_usage::emit_metric_for_tool_read;
use crate::memory_usage::shell_script_for_invocation;
use crate::session::session::Session;
use crate::session::turn_context::TurnContext;
use crate::tools::context::FunctionToolOutput;
use crate::tools::context::ToolCallState;
use crate::tools::context::ToolEnvironments;
use crate::tools::context::ToolInvocation;
use crate::tools::context::ToolOutput;
use crate::tools::context::ToolPayload;
use crate::tools::control_tool_analytics::ControlToolCallGuard;
use crate::tools::flat_tool_name;
use crate::tools::handlers::multi_agents_spec::MULTI_AGENT_V1_NAMESPACE;
use crate::tools::hook_names::HookToolName;
use crate::tools::lifecycle::notify_tool_finish;
use crate::tools::lifecycle::notify_tool_start;
use crate::tools::router::tool_log_payload;
use crate::tools::tool_dispatch_trace::ToolDispatchTrace;
use crate::util::error_or_panic;
use codex_analytics::ControlToolCallStatus;
use codex_extension_api::ToolCallOutcome;
use codex_extension_api::ToolPolicy;
use codex_history::CodexHarnessMetadata;
use codex_history::ResponseItemEnvelope;
use codex_protocol::models::FunctionCallOutputPayload;
use codex_protocol::models::ResponseInputItem;
use codex_protocol::parse_command::ParsedCommand;
use codex_protocol::protocol::EventMsg;
use codex_rollout::state_db;
use codex_shell_command::parse_command::parse_shell_script;
use codex_tools::FunctionsNamespaceFunctionPrefixes;
use codex_tools::ToolName;
use codex_tools::ToolSearchInfo;
use codex_tools::ToolSpec;
use codex_utils_path_uri::PathUri;
use futures::future::BoxFuture;
use indexmap::IndexMap;
use indexmap::map::Entry;
use serde_json::Value;

pub(crate) type LiveEnvironmentResolver =
    fn(&ToolInvocation) -> BoxFuture<'_, Result<ToolEnvironments, FunctionCallError>>;

pub(crate) type ToolTelemetryTags = Vec<(&'static str, String)>;

pub use codex_tools::ToolExecutor;
pub use codex_tools::ToolExposure;

/// Typed runtime contract for locally executed tools.
///
/// Implementers provide the shared `ToolExecutor` behavior plus optional
/// core-owned metadata for hooks, telemetry, tool search, and argument diffs.
pub(crate) trait CoreToolRuntime: ToolExecutor<ToolInvocation> {
    /// The handler observes its cancellation token and must finish before dispatch is aborted.
    fn finishes_on_cancellation(&self) -> bool {
        false
    }

    /// Whether this built-in control tool needs a structured tool-call event.
    fn is_builtin_control_tool(&self) -> bool {
        false
    }

    /// Returns a shared spec when both the spec and search metadata are immutable.
    fn immutable_spec(&self) -> Option<&Arc<ToolSpec>> {
        None
    }

    /// Returns lazily cached, augmented Code Mode definitions owned by this runtime.
    /// Input and output schemas must be cleared after rendering their declarations.
    /// Return None when the requested schema budget differs from the cached budget.
    fn cached_code_mode_definitions(
        &self,
        _code_mode_input_schema_max_bytes: Option<usize>,
    ) -> Option<&[codex_code_mode::ToolDefinition]> {
        None
    }

    /// Returns a readiness wait for this exact tool before taking the execution gate.
    fn wait_until_ready<'a>(&'a self, _session: &'a Arc<Session>) -> Option<BoxFuture<'a, ()>> {
        None
    }

    /// True for MCP/app and client-supplied dynamic tools.
    /// A built-in stays false even if a client's tool has the same name.
    fn is_third_party_tool(&self) -> bool {
        false
    }

    /// Identify the environments selected by the original input.
    fn environments_for_input(
        &self,
        _invocation: &ToolInvocation,
    ) -> Result<ToolEnvironments, FunctionCallError> {
        Ok(ToolEnvironments::All)
    }

    /// Select a shared resolver when the environment belongs to a live resource.
    fn live_environment_resolver(&self) -> Option<LiveEnvironmentResolver> {
        None
    }

    /// Returns the owning server only for MCP-backed tool runtimes.
    fn mcp_server_name(&self) -> Option<&str> {
        None
    }

    fn matches_kind(&self, payload: &ToolPayload) -> bool {
        matches!(
            payload,
            ToolPayload::Function { .. } | ToolPayload::ToolSearch { .. }
        )
    }

    fn telemetry_tags(&self, _invocation: &ToolInvocation) -> ToolTelemetryTags {
        Vec::new()
    }

    /// Observes a tool result only after all PostToolUse hooks accept it.
    fn on_tool_result_accepted(&self, _invocation: &ToolInvocation, _result: &dyn ToolOutput) {}

    fn post_tool_use_payload(
        &self,
        invocation: &ToolInvocation,
        result: &dyn ToolOutput,
    ) -> Option<PostToolUsePayload> {
        let ToolPayload::Function { arguments } = &invocation.payload else {
            return None;
        };

        Some(PostToolUsePayload {
            tool_cwd: result.post_tool_use_cwd(),
            tool_name: function_hook_tool_name(invocation),
            tool_use_id: result.post_tool_use_id(&invocation.call_id),
            tool_input: result
                .post_tool_use_input(&invocation.payload)
                .unwrap_or_else(|| function_hook_tool_input(arguments)),
            tool_response: result
                .post_tool_use_response(&invocation.call_id, &invocation.payload)
                .or_else(|| {
                    // Most function tools can expose their model-facing output
                    // as the hook response. Outputs with a more stable hook
                    // contract should override post_tool_use_response above.
                    let ResponseInputItem::FunctionCallOutput {
                        output: FunctionCallOutputPayload { body, .. },
                        ..
                    } = result.to_response_item(&invocation.call_id, &invocation.payload)
                    else {
                        return None;
                    };

                    serde_json::to_value(body).ok()
                })?,
        })
    }

    fn pre_tool_use_payload(&self, invocation: &ToolInvocation) -> Option<PreToolUsePayload> {
        let ToolPayload::Function { arguments } = &invocation.payload else {
            return None;
        };

        Some(PreToolUsePayload {
            tool_name: function_hook_tool_name(invocation),
            tool_input: function_hook_tool_input(arguments),
        })
    }

    /// Resolves a local execution cwd exposed in `PreToolUse` stdin, when the tool
    /// supports a per-call working directory. Remote commands return `None` to
    /// retain the host cwd. This does not move the hook process.
    fn pre_tool_use_cwd(
        &self,
        _invocation: &ToolInvocation,
    ) -> Result<Option<PathUri>, FunctionCallError> {
        Ok(None)
    }

    /// Rebuilds a tool invocation from hook-facing `tool_input`.
    ///
    /// Tools that opt into input-rewriting hooks should invert the same stable
    /// hook contract they expose from `pre_tool_use_payload`.
    fn with_updated_hook_input(
        &self,
        invocation: ToolInvocation,
        updated_input: Value,
    ) -> Result<ToolInvocation, FunctionCallError> {
        with_updated_function_input(invocation, updated_input)
    }

    /// Creates an optional consumer for streamed tool argument diffs.
    fn create_diff_consumer(&self) -> Option<Box<dyn ToolArgumentDiffConsumer>> {
        None
    }
}

pub(super) fn with_updated_function_input(
    invocation: ToolInvocation,
    mut updated_input: Value,
) -> Result<ToolInvocation, FunctionCallError> {
    let ToolPayload::Function { .. } = &invocation.payload else {
        return Err(FunctionCallError::RespondToModel(
            "hook input rewrite received unsupported function tool payload".to_string(),
        ));
    };

    match &invocation.environments {
        ToolEnvironments::Arguments(environments) => {
            for (field, environment) in environments {
                preserve_hook_selector(
                    &mut updated_input,
                    field,
                    serde_json::json!(environment.selection.environment_id),
                )?;
            }
        }
        ToolEnvironments::Mcp { server, .. } => {
            if let Some(Value::String(value)) = updated_input.get_mut("server") {
                *value = value.trim().to_owned();
                if value.is_empty() {
                    updated_input["server"] = Value::Null;
                }
            }
            preserve_hook_selector(&mut updated_input, "server", serde_json::json!(server))?;
        }
        ToolEnvironments::Terminal(terminal) => {
            preserve_hook_selector(
                &mut updated_input,
                "session_id",
                serde_json::json!(terminal.process_id),
            )?;
        }
        ToolEnvironments::All => {}
    }
    let arguments = serde_json::to_string(&updated_input).map_err(|err| {
        FunctionCallError::RespondToModel(format!(
            "failed to serialize rewritten {} arguments: {err}",
            flat_tool_name(&invocation.tool_name)
        ))
    })?;
    Ok(ToolInvocation {
        payload: ToolPayload::Function { arguments },
        ..invocation
    })
}

/// A rewrite may omit the selector or repeat its original value.
fn preserve_hook_selector(
    input: &mut Value,
    field: &str,
    expected: Value,
) -> Result<(), FunctionCallError> {
    let object = input.as_object_mut().ok_or_else(|| {
        FunctionCallError::RespondToModel(
            "expected an object for rewritten tool arguments".to_string(),
        )
    })?;
    if let Some(value) = object.get(field)
        && value != &expected
    {
        return Err(FunctionCallError::RespondToModel(format!(
            "PreToolUse hook cannot change the tool environment ({field})"
        )));
    }
    if !expected.is_null() {
        object.insert(field.to_string(), expected);
    }
    Ok(())
}

/// Consumes streamed argument diffs for a tool call and emits protocol events
/// derived from partial tool input.
pub(crate) trait ToolArgumentDiffConsumer: Send {
    /// Consume the next argument diff for a tool call.
    fn consume_diff(&mut self, turn: &TurnContext, call_id: String, diff: &str)
    -> Option<EventMsg>;

    /// Finish consuming argument diffs before the tool call completes.
    fn finish(&mut self) -> Result<Option<EventMsg>, FunctionCallError> {
        Ok(None)
    }
}

pub(crate) struct AnyToolResult {
    pub(crate) call_id: String,
    pub(crate) payload: ToolPayload,
    pub(crate) result: Box<dyn ToolOutput>,
    pub(crate) post_tool_use_payload: Option<PostToolUsePayload>,
}

impl AnyToolResult {
    pub(crate) fn into_response(self) -> ResponseItemEnvelope {
        let Self {
            call_id,
            payload,
            result,
            ..
        } = self;
        let history_truncation_token_limit = result.fallback_token_limit_override();
        ResponseItemEnvelope {
            item: result.to_response_item(&call_id, &payload).into(),
            metadata: history_truncation_token_limit.map(|limit| CodexHarnessMetadata {
                history_truncation_token_limit: Some(limit),
                ..Default::default()
            }),
        }
    }

    pub(crate) fn code_mode_result(self) -> serde_json::Value {
        let Self {
            payload, result, ..
        } = self;
        result.code_mode_result(&payload)
    }
}

struct PostToolUseFeedbackOutput {
    original: Box<dyn ToolOutput>,
    model_visible: FunctionToolOutput,
}

impl ToolOutput for PostToolUseFeedbackOutput {
    fn log_output(&self) -> String {
        self.original.log_output()
    }

    fn success_for_logging(&self) -> bool {
        self.original.success_for_logging()
    }

    fn set_handler_duration_ms(&mut self, handler_duration_ms: u64) {
        self.original.set_handler_duration_ms(handler_duration_ms);
    }

    fn fallback_token_limit_override(&self) -> Option<usize> {
        self.original.fallback_token_limit_override()
    }

    fn to_response_item(&self, call_id: &str, payload: &ToolPayload) -> ResponseInputItem {
        self.model_visible.to_response_item(call_id, payload)
    }

    fn code_mode_result(&self, payload: &ToolPayload) -> Value {
        self.original.code_mode_result(payload)
    }

    fn tool_result_metadata(&self) -> Option<&Value> {
        self.original.tool_result_metadata()
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub(crate) struct PreToolUsePayload {
    /// Hook-facing tool name model.
    ///
    /// The canonical name is serialized to hook stdin, while aliases are used
    /// only for matcher compatibility.
    pub(crate) tool_name: HookToolName,
    /// Tool-specific input exposed at `tool_input`.
    ///
    /// Shell-like tools use `{ "command": ... }`; MCP tools use their resolved
    /// JSON arguments.
    pub(crate) tool_input: Value,
}

#[derive(Debug, Clone, PartialEq)]
pub(crate) struct PostToolUsePayload {
    /// Local execution cwd used by hook input; remote tools retain the host fallback.
    pub(crate) tool_cwd: Option<PathUri>,
    /// Hook-facing tool name model.
    ///
    /// The canonical name is serialized to hook stdin, while aliases are used
    /// only for matcher compatibility.
    pub(crate) tool_name: HookToolName,
    /// The originating tool-use id exposed at `tool_use_id`.
    pub(crate) tool_use_id: String,
    /// Tool-specific input exposed at `tool_input`.
    pub(crate) tool_input: Value,
    /// Tool result exposed at `tool_response`.
    pub(crate) tool_response: Value,
}

/// Captured with the tool plan; review runs after hooks using the rewritten arguments.
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub(crate) enum NativeReview {
    #[default]
    Disabled,
    Required,
}

/// A tool runtime together with its effective exposure and review policy for the current step.
pub(crate) struct RegisteredTool {
    pub(crate) runtime: Arc<dyn CoreToolRuntime>,
    pub(crate) exposure: ToolExposure,
    pub(crate) native_review: NativeReview,
    /// Per-step description override; never written back to a shared runtime.
    pub(crate) model_spec: Option<Arc<ToolSpec>>,
}

impl RegisteredTool {
    /// Direct declarations and Code Mode read this spec; execution uses the runtime.
    pub(crate) fn spec(&self) -> Arc<ToolSpec> {
        self.model_spec
            .as_ref()
            .or_else(|| self.runtime.immutable_spec())
            .cloned()
            .unwrap_or_else(|| Arc::new(self.runtime.spec()))
    }

    /// Runtime caches describe the original spec, so cannot serve an overridden one.
    pub(crate) fn cached_runtime(&self) -> Option<&Arc<dyn CoreToolRuntime>> {
        (self.model_spec.is_none() && self.runtime.immutable_spec().is_some())
            .then_some(&self.runtime)
    }
}

#[derive(Default)]
pub struct ToolRegistry {
    tools: IndexMap<ToolName, RegisteredTool>,
    functions_namespace_function_prefixes: FunctionsNamespaceFunctionPrefixes,
    first_collision: Option<ToolName>,
    pub(crate) tool_policy: Arc<ToolPolicy>,
}

impl ToolRegistry {
    pub(crate) fn search_info(&self, tool: &RegisteredTool) -> Option<ToolSearchInfo> {
        let info = tool.runtime.search_info()?;
        // A runtime may advertise a different search schema or description. Preserve it,
        // along with its ranking text and source, rather than substituting the normal spec.
        match self
            .functions_namespace_function_prefixes
            .prepare(&tool.runtime.tool_name(), || {
                info.entry.to_loadable_spec().into()
            }) {
            Some(spec) => ToolSearchInfo::from_spec(info.entry.search_text, spec, info.source_info),
            None => Some(info),
        }
    }

    /// Apply catalog prefixes to this step's specs, budgeting only reachable tools.
    /// The planner supplies the names; this does not change execution or exposure.
    pub(crate) fn apply_functions_namespace_function_prefixes(
        &mut self,
        prefixes: Option<&BTreeMap<String, String>>,
        available_tools: impl IntoIterator<Item = ToolName>,
    ) -> Result<(), &'static str> {
        let prefixes = FunctionsNamespaceFunctionPrefixes::new(prefixes, available_tools)?;
        for tool in self.tools.values_mut() {
            tool.model_spec = prefixes
                .prepare(&tool.runtime.tool_name(), || tool.runtime.spec())
                .map(Arc::new);
        }
        self.functions_namespace_function_prefixes = prefixes;
        Ok(())
    }

    fn prepare_tool(
        &self,
        runtime: Arc<dyn CoreToolRuntime>,
        exposure: ToolExposure,
    ) -> RegisteredTool {
        let model_spec = self
            .functions_namespace_function_prefixes
            .prepare(&runtime.tool_name(), || runtime.spec())
            .map(Arc::new);
        RegisteredTool {
            runtime,
            exposure,
            native_review: NativeReview::Disabled,
            model_spec,
        }
    }

    pub(crate) fn with_tool_policy(tool_policy: Arc<ToolPolicy>) -> Self {
        Self {
            tool_policy,
            ..Self::default()
        }
    }

    #[cfg(test)]
    pub(crate) fn from_tools(tools: impl IntoIterator<Item = Arc<dyn CoreToolRuntime>>) -> Self {
        let mut registry = Self::default();

        for runtime in tools {
            registry.register_trusted(runtime);
        }

        registry
    }

    pub(crate) fn add<T>(&mut self, handler: T)
    where
        T: CoreToolRuntime + 'static,
    {
        self.register_trusted(Arc::new(handler));
    }

    pub(crate) fn add_with_exposure<T>(&mut self, handler: T, exposure: ToolExposure)
    where
        T: CoreToolRuntime + 'static,
    {
        self.register_trusted_with_exposure(Arc::new(handler), exposure);
    }

    pub(crate) fn register_trusted(&mut self, runtime: Arc<dyn CoreToolRuntime>) {
        let exposure = runtime.exposure();
        self.register_trusted_with_exposure(runtime, exposure);
    }

    pub(crate) fn register_trusted_with_exposure(
        &mut self,
        runtime: Arc<dyn CoreToolRuntime>,
        exposure: ToolExposure,
    ) {
        self.register_trusted_with_native_review(runtime, exposure, NativeReview::Disabled);
    }

    pub(crate) fn register_trusted_with_native_review(
        &mut self,
        runtime: Arc<dyn CoreToolRuntime>,
        exposure: ToolExposure,
        native_review: NativeReview,
    ) {
        let tool_name = runtime.tool_name().with_default_namespace();
        if !self.tool_policy.allows(&tool_name) {
            return;
        }
        let mut tool = self.prepare_tool(runtime, exposure);
        tool.native_review = native_review;
        match self.tools.entry(tool_name) {
            Entry::Vacant(entry) => {
                entry.insert(tool);
            }
            Entry::Occupied(entry) => {
                let tool_name = entry.key();
                error_or_panic(format!("tool {tool_name} already registered"));
            }
        }
    }

    pub(crate) fn prepend_trusted(&mut self, runtime: Arc<dyn CoreToolRuntime>) {
        let tool_name = runtime.tool_name().with_default_namespace();
        if !self.tool_policy.allows(&tool_name) {
            return;
        }
        if self.tools.contains_key(&tool_name) {
            error_or_panic(format!("tool {tool_name} already registered"));
            return;
        }

        let exposure = runtime.exposure();
        let tool = self.prepare_tool(runtime, exposure);
        self.tools.shift_insert(0, tool_name, tool);
    }

    pub(crate) fn register_external(&mut self, runtime: Arc<dyn CoreToolRuntime>) -> bool {
        let exposure = runtime.exposure();
        self.register_external_with_exposure(runtime, exposure)
    }

    pub(crate) fn register_external_with_exposure(
        &mut self,
        runtime: Arc<dyn CoreToolRuntime>,
        exposure: ToolExposure,
    ) -> bool {
        let tool_name = runtime.tool_name().with_default_namespace();
        if !self.tool_policy.allows(&tool_name) {
            return false;
        }
        if tool_name.is_default_namespace()
            && matches!(tool_name.name.as_str(), "exec_command" | "shell_command")
        {
            tracing::warn!(tool_name = %tool_name, "skipping external tool with reserved name");
            if self.tools.contains_key(&tool_name) {
                self.record_collision(tool_name);
            }
            return false;
        }

        let tool = self.prepare_tool(runtime, exposure);
        match self.tools.entry(tool_name) {
            Entry::Vacant(entry) => {
                entry.insert(tool);
                true
            }
            Entry::Occupied(entry) => {
                tracing::warn!(
                    tool_name = %entry.key(),
                    "skipping duplicate external tool that is already registered"
                );
                self.first_collision
                    .get_or_insert_with(|| entry.key().clone());
                false
            }
        }
    }

    pub(crate) fn record_collision(&mut self, tool_name: ToolName) {
        self.first_collision.get_or_insert(tool_name);
    }

    pub(crate) fn first_collision(&self) -> Option<&ToolName> {
        self.first_collision.as_ref()
    }

    pub(crate) fn remove(&mut self, tool_name: &ToolName) -> Option<Arc<dyn CoreToolRuntime>> {
        self.tools
            .shift_remove(&tool_name.clone().with_default_namespace())
            .map(|tool| tool.runtime)
    }

    pub(crate) fn entries(&self) -> impl Iterator<Item = &RegisteredTool> {
        self.tools.values()
    }

    pub(crate) fn entries_mut(&mut self) -> impl Iterator<Item = &mut RegisteredTool> {
        self.tools.values_mut()
    }

    /// Returns configured MCP server names and their registered callable namespaces.
    pub(crate) fn mcp_namespaces(&self) -> impl Iterator<Item = (&str, &str)> {
        self.tools.iter().filter_map(|(name, tool)| {
            Some((tool.runtime.mcp_server_name()?, name.namespace.as_deref()?))
        })
    }

    pub(crate) fn deferred_tool_namespaces(&self) -> BTreeMap<String, String> {
        let mut namespaces = BTreeMap::<String, String>::new();
        for (name, tool) in &self.tools {
            if !tool.exposure.is_deferred() || name.is_default_namespace() {
                continue;
            }
            let Some(namespace) = &name.namespace else {
                continue;
            };
            let existing_description = namespaces.entry(namespace.clone()).or_default();
            if !existing_description.trim().is_empty() {
                continue;
            }
            let owned_spec;
            let spec = if let Some(spec) = tool.runtime.immutable_spec() {
                spec.as_ref()
            } else {
                owned_spec = tool.runtime.spec();
                &owned_spec
            };
            let description = match spec {
                ToolSpec::Namespace(namespace) => namespace.description.as_str(),
                ToolSpec::Function(_)
                | ToolSpec::Freeform(_)
                | ToolSpec::ToolSearch { .. }
                | ToolSpec::WebSearch { .. } => "",
            };
            if !description.trim().is_empty() {
                *existing_description = description.to_string();
            }
        }
        namespaces
    }

    #[cfg(test)]
    pub(crate) fn empty_for_test() -> Self {
        Self::from_tools(std::iter::empty())
    }

    #[cfg(test)]
    pub(crate) fn with_handler_for_test<T>(handler: Arc<T>) -> Self
    where
        T: CoreToolRuntime + 'static,
    {
        Self::from_tools([handler as Arc<dyn CoreToolRuntime>])
    }

    pub(crate) fn tool(&self, name: &ToolName) -> Option<Arc<dyn CoreToolRuntime>> {
        self.registered_tool(name)
            .map(|tool| Arc::clone(&tool.runtime))
    }

    pub(crate) fn registered_tool(&self, name: &ToolName) -> Option<&RegisteredTool> {
        self.tools.get(&name.clone().with_default_namespace())
    }

    #[cfg(test)]
    pub(crate) fn tool_names_for_test(&self) -> Vec<ToolName> {
        let mut names = self.tools.keys().cloned().collect::<Vec<_>>();
        names.sort();
        names
    }

    #[cfg(test)]
    pub(crate) fn tool_exposure(&self, name: &ToolName) -> Option<ToolExposure> {
        self.tools
            .get(&name.clone().with_default_namespace())
            .map(|tool| tool.exposure)
    }

    pub(crate) fn create_diff_consumer(
        &self,
        name: &ToolName,
    ) -> Option<Box<dyn ToolArgumentDiffConsumer>> {
        self.tool(name)?.create_diff_consumer()
    }

    pub(crate) fn supports_parallel_tool_calls(&self, name: &ToolName) -> Option<bool> {
        let tool = self.tools.get(&name.clone().with_default_namespace())?;
        Some(tool.exposure != ToolExposure::Hidden && tool.runtime.supports_parallel_tool_calls())
    }

    #[expect(
        clippy::await_holding_invalid_type,
        reason = "tool dispatch must keep active-turn accounting atomic"
    )]
    pub(crate) async fn dispatch_any_with_state(
        &self,
        mut invocation: ToolInvocation,
        call_state: Option<Arc<ToolCallState>>,
    ) -> Result<AnyToolResult, FunctionCallError> {
        // Standalone dispatch has no outer task to reserve the ID for it.
        let standalone;
        let reservation = if let Some(state) = &call_state {
            &state.invocation
        } else {
            standalone = crate::agent::host::InvocationReservation::default();
            standalone.reserve(&invocation.session, &invocation.turn, &invocation.call_id)?;
            &standalone
        };
        let cancellation_token = invocation.cancellation_token.clone();
        let tool_name = invocation.tool_name.clone();
        let call_id_owned = invocation.call_id.clone();
        let otel = invocation
            .step_context
            .session_telemetry
            .clone()
            .with_product_sku(invocation.turn.config.apps_mcp_product_sku.as_deref());
        // TODO(anp): Reconcile these tags with TurnEnvironment::sandbox_context
        // instead of reporting the thread-wide backend for environment-scoped tools.
        let sandbox_tags = invocation.turn.turn_metadata_state.sandbox_tags;

        {
            let mut active = invocation
                .session
                .active_turn
                .lock()
                .or_cancel_tool(&cancellation_token)
                .await?;
            if let Some(active_turn) = active.as_mut() {
                let mut turn_state = active_turn
                    .turn_state
                    .lock()
                    .or_cancel_tool(&cancellation_token)
                    .await?;
                turn_state.tool_calls = turn_state.tool_calls.saturating_add(1);
            }
        }

        let dispatch_trace = ToolDispatchTrace::start(&invocation);
        let registered_tool = match self.registered_tool(&tool_name) {
            Some(tool) => tool,
            None => {
                let message = unsupported_tool_call_message(&invocation.payload, &tool_name);
                let log_payload = tool_log_payload(&invocation.payload, &invocation.source);
                let mut tool_result_tags = Vec::with_capacity(2);
                sandbox_tags.append_metric_tags(&mut tool_result_tags);
                otel.tool_result_with_tags(
                    &tool_name,
                    &call_id_owned,
                    log_payload.as_ref(),
                    Duration::ZERO,
                    /*success*/ false,
                    &message,
                    &tool_result_tags,
                    /*extra_trace_fields*/ &[],
                );
                let err = FunctionCallError::RespondToModel(message);
                dispatch_trace.record_failed(&err);
                return Err(err);
            }
        };
        let tool = Arc::clone(&registered_tool.runtime);
        let telemetry_tags = tool.telemetry_tags(&invocation);
        let mut tool_result_tags = Vec::with_capacity(2 + telemetry_tags.len() + 1);
        let mut extra_trace_fields = Vec::new();
        sandbox_tags.append_metric_tags(&mut tool_result_tags);
        for (key, value) in &telemetry_tags {
            if matches!(*key, "mcp_server" | "mcp_server_origin") {
                extra_trace_fields.push((*key, value.as_str()));
            } else {
                tool_result_tags.push((*key, value.as_str()));
            }
        }
        if !tool.matches_kind(&invocation.payload) {
            let message = format!("tool {tool_name} invoked with incompatible payload");
            let log_payload = tool_log_payload(&invocation.payload, &invocation.source);
            otel.tool_result_with_tags(
                &tool_name,
                &call_id_owned,
                log_payload.as_ref(),
                Duration::ZERO,
                /*success*/ false,
                &message,
                &tool_result_tags,
                &extra_trace_fields,
            );
            let err = FunctionCallError::Fatal(message);
            dispatch_trace.record_failed(&err);
            return Err(err);
        }

        let fail_before_execution = async |invocation: &ToolInvocation, err: FunctionCallError| {
            let log_payload = tool_log_payload(&invocation.payload, &invocation.source);
            otel.tool_result_with_tags(
                &tool_name,
                &call_id_owned,
                log_payload.as_ref(),
                Duration::ZERO,
                /*success*/ false,
                &err.to_string(),
                &tool_result_tags,
                &extra_trace_fields,
            );
            if tool.is_builtin_control_tool() {
                let mut analytics = ControlToolCallGuard::new(invocation);
                analytics.finish(ControlToolCallStatus::Failed);
            }
            dispatch_trace.record_failed(&err);
            notify_tool_finish_if_unclaimed(
                invocation,
                call_state.as_deref(),
                ToolCallOutcome::Failed {
                    handler_executed: false,
                },
            )
            .await;
            err
        };
        let environments = match tool.live_environment_resolver() {
            Some(resolve) => resolve(&invocation).await,
            None => tool.environments_for_input(&invocation),
        };
        invocation.environments = match environments {
            Ok(environments) => environments,
            Err(err) => return Err(fail_before_execution(&invocation, err).await),
        };
        if let Some(pre_tool_use_payload) = tool.pre_tool_use_payload(&invocation) {
            let tool_cwd = match tool.pre_tool_use_cwd(&invocation) {
                Ok(cwd) => cwd,
                Err(err) => return Err(fail_before_execution(&invocation, err).await),
            };
            match run_pre_tool_use_hooks(
                &invocation.session,
                invocation.step_context.as_ref(),
                invocation.call_id.clone(),
                &pre_tool_use_payload.tool_name,
                &pre_tool_use_payload.tool_input,
                tool_cwd,
                &invocation.environments.hook_ids(),
            )
            .or_cancel_tool(&cancellation_token)
            .await?
            {
                PreToolUseHookResult::Blocked(message) => {
                    if tool.is_builtin_control_tool() {
                        let mut analytics = ControlToolCallGuard::new(&invocation);
                        analytics.finish(ControlToolCallStatus::Rejected);
                    }
                    let err = FunctionCallError::RespondToModel(message);
                    dispatch_trace.record_failed(&err);
                    notify_tool_finish_if_unclaimed(
                        &invocation,
                        call_state.as_deref(),
                        ToolCallOutcome::Blocked,
                    )
                    .await;
                    return Err(err);
                }
                PreToolUseHookResult::Continue {
                    updated_input: Some(updated_input),
                } => match tool.with_updated_hook_input(invocation.clone(), updated_input) {
                    Ok(mut updated_invocation) => {
                        if updated_invocation.payload != invocation.payload {
                            Arc::make_mut(&mut updated_invocation.step_context)
                                .serving_assessment = None;
                        }
                        invocation = updated_invocation;
                    }
                    Err(err) => return Err(fail_before_execution(&invocation, err).await),
                },
                PreToolUseHookResult::Continue {
                    updated_input: None,
                } => {}
            }
        }

        if let Some(assessment) = &invocation.step_context.serving_assessment {
            let mut assessment = assessment.as_ref().clone();
            match crate::guardian::tool_permission_context(&invocation) {
                Ok(permissions) => assessment.authorization.permissions = permissions,
                Err(_) => assessment.requires_review = true,
            }
            Arc::make_mut(&mut invocation.step_context).serving_assessment =
                Some(Arc::new(assessment));
        }

        if registered_tool.native_review == NativeReview::Required
            && let Err(err) = super::review_native_tool_call(&invocation).await
        {
            return Err(fail_before_execution(&invocation, err).await);
        }

        let invocation_guard = reservation.activate(&invocation);
        if tool.mcp_server_name().is_none() {
            notify_tool_start(&invocation, /*mcp_tool*/ None)
                .or_cancel_tool(&cancellation_token)
                .await?;
        }
        let mut control_tool_analytics = tool
            .is_builtin_control_tool()
            .then(|| ControlToolCallGuard::new(&invocation));

        if let Some(command) = shell_script_for_invocation(&invocation) {
            let parsed = parse_shell_script(&command);
            let mut categories = parsed.iter().map(|command| match command {
                ParsedCommand::Read { .. } => "read",
                ParsedCommand::ListFiles { .. } => "list_files",
                ParsedCommand::Search { .. } => "search",
                ParsedCommand::Unknown { .. } => "unknown",
            });
            let category = match categories.next() {
                Some(first) if categories.all(|category| category == first) => first,
                Some(_) => "mixed",
                None => "unknown",
            };
            tool_result_tags.push(("command_category", category));
        }

        let log_payload = tool_log_payload(&invocation.payload, &invocation.source);

        let result = otel
            .log_tool_result_with_tags(
                &tool_name,
                &call_id_owned,
                log_payload.as_ref(),
                &tool_result_tags,
                &extra_trace_fields,
                || handle_any_tool(tool.as_ref(), invocation.clone(), call_state.as_deref()),
                |result| {
                    (
                        result.result.log_output(),
                        result.result.success_for_logging(),
                    )
                },
            )
            .await;
        let success = match &result {
            Ok(result) => result.result.success_for_logging(),
            Err(_) => false,
        };
        if let Some(analytics) = control_tool_analytics.as_mut() {
            analytics.finish(if success {
                ControlToolCallStatus::Completed
            } else {
                ControlToolCallStatus::Failed
            });
        }
        emit_metric_for_tool_read(&invocation, success);
        let post_tool_use_payload = if success {
            result
                .as_ref()
                .ok()
                .and_then(|result| result.post_tool_use_payload.clone())
        } else {
            None
        };
        let post_tool_use_outcome = if let Some(post_tool_use_payload) = post_tool_use_payload {
            Some(
                run_post_tool_use_hooks(
                    &invocation.session,
                    invocation.step_context.as_ref(),
                    post_tool_use_payload,
                    &invocation.environments.hook_ids(),
                )
                .or_cancel_tool(&cancellation_token)
                .await?,
            )
        } else {
            None
        };
        if let Some(outcome) = &post_tool_use_outcome {
            record_additional_contexts(
                &invocation.session,
                &invocation.turn,
                outcome.additional_contexts.clone(),
            )
            .or_cancel_tool(&cancellation_token)
            .await?;
        }

        // A PostToolUse block rejects the result, not the already-completed tool execution.
        let lifecycle_outcome = match &result {
            _ if tool.finishes_on_cancellation()
                && invocation.cancellation_token.is_cancelled() =>
            {
                ToolCallOutcome::Aborted
            }
            Ok(_) => ToolCallOutcome::Completed { success },
            Err(_) => ToolCallOutcome::Failed {
                handler_executed: true,
            },
        };
        drop(invocation_guard);
        notify_tool_finish_if_unclaimed(&invocation, call_state.as_deref(), lifecycle_outcome)
            .await;

        match result {
            Ok(mut result) => {
                if let Some(outcome) = post_tool_use_outcome {
                    if outcome.should_block {
                        let message = outcome.feedback_message.unwrap_or_else(|| {
                            "PostToolUse hook blocked the tool result".to_string()
                        });
                        let err = FunctionCallError::RespondToModel(message);
                        dispatch_trace.record_failed(&err);
                        return Err(err);
                    }
                    if let Some(feedback_message) = outcome.feedback_message {
                        result.result = Box::new(PostToolUseFeedbackOutput {
                            original: result.result,
                            model_visible: FunctionToolOutput::from_text(
                                feedback_message,
                                /*success*/ None,
                            ),
                        });
                    }
                }
                tool.on_tool_result_accepted(&invocation, result.result.as_ref());
                dispatch_trace.record_completed(
                    &invocation,
                    &result.call_id,
                    &result.payload,
                    result.result.as_ref(),
                );
                Ok(result)
            }
            Err(err) => {
                dispatch_trace.record_failed(&err);
                Err(err)
            }
        }
    }
}

async fn notify_tool_finish_if_unclaimed(
    invocation: &ToolInvocation,
    call_state: Option<&ToolCallState>,
    outcome: ToolCallOutcome,
) -> bool {
    if call_state.is_some_and(|state| state.terminal_outcome_reached.swap(true, Ordering::AcqRel)) {
        return false;
    }

    notify_tool_finish(invocation, outcome).await;
    true
}

async fn handle_any_tool(
    tool: &dyn CoreToolRuntime,
    invocation: ToolInvocation,
    call_state: Option<&ToolCallState>,
) -> Result<AnyToolResult, FunctionCallError> {
    let call_id = invocation.call_id.clone();
    let payload = invocation.payload.clone();
    let output = tool.handle(invocation.clone()).await?;
    let post_tool_use_payload =
        CoreToolRuntime::post_tool_use_payload(tool, &invocation, output.as_ref());
    let result = AnyToolResult {
        call_id,
        payload,
        result: output,
        post_tool_use_payload,
    };
    super::user_messaging::capture_delivery(&result, call_state);
    if result.result.contains_external_context()
        && invocation.turn.config.memories.disable_on_external_context
    {
        state_db::mark_thread_memory_mode_polluted(
            invocation.session.services.state_db.as_deref(),
            invocation.session.thread_id,
            "tool_output",
        )
        .or_cancel_tool(&invocation.cancellation_token)
        .await?;
    }
    Ok(result)
}

fn function_hook_tool_name(invocation: &ToolInvocation) -> HookToolName {
    if invocation.tool_name.name == "spawn_agent"
        && (invocation.tool_name.is_default_namespace()
            || invocation.tool_name.namespace.as_deref() == Some(MULTI_AGENT_V1_NAMESPACE))
    {
        return HookToolName::spawn_agent();
    }

    HookToolName::new(flat_tool_name(&invocation.tool_name).into_owned())
}

fn function_hook_tool_input(arguments: &str) -> Value {
    if arguments.trim().is_empty() {
        return Value::Object(serde_json::Map::new());
    }

    serde_json::from_str(arguments).unwrap_or_else(|_| Value::String(arguments.to_string()))
}

fn unsupported_tool_call_message(payload: &ToolPayload, tool_name: &ToolName) -> String {
    match payload {
        ToolPayload::Custom { .. } => format!("unsupported custom tool call: {tool_name}"),
        _ => format!("unsupported call: {tool_name}"),
    }
}
#[cfg(test)]
#[path = "registry_tests.rs"]
mod tests;