zagens-core 0.8.2

Core runtime boundaries for Zagens agent architecture
Documentation
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//! Tool planning + outcome aggregation for one turn step (P2 PR6b — `zagens-core`).

use serde_json::json;
use std::collections::HashSet;
use zagens_tools::{ToolError, ToolResult};

use crate::chat::{ContentBlock, Message, Tool};
use crate::engine::context::{compact_tool_result_for_context, summarize_text};
use crate::engine::dispatch::{
    caller_allowed_for_tool, caller_type_for_tool_use, format_tool_error,
    should_stop_after_plan_tool,
};
use crate::engine::emit_tool_audit;
use crate::engine::kernel_event::{KernelEvent, PolicyDecision, ToolOutcome as KernelToolOutcome};
use crate::engine::loop_guard::{AttemptDecision, LoopGuard, OutcomeDecision};
use crate::engine::streaming::ToolUseState;
use crate::engine::tool_catalog::{
    CODE_EXECUTION_TOOL_NAME, REQUEST_USER_INPUT_NAME, is_audit_scratchpad_bind_tool,
    is_tool_search_tool, missing_tool_error_message, scratchpad_defer_set_area_batch_error,
};
use crate::engine::tool_effects::tool_writes_state;
use crate::engine::turn_loop::control::TurnLoopToolPhaseOutcome;
use crate::engine::turn_loop::exec::ToolExecutionPlan;
use crate::engine::turn_loop::inner_step_host::InnerStepHost;
use crate::engine::turn_machine::emit_kernel_event;
use crate::error_taxonomy::ErrorEnvelope;
use crate::turn::{TurnContext, TurnLoopMode, TurnToolCall};

#[allow(clippy::too_many_arguments)]
pub async fn run_tool_execution_phase<H: InnerStepHost>(
    host: &mut H,
    turn: &mut TurnContext,
    mode: TurnLoopMode,
    tool_uses: &mut [ToolUseState],
    tool_catalog: &mut [Tool],
    active_tool_names: &mut HashSet<String>,
    loop_guard: &mut LoopGuard,
    consecutive_tool_error_steps: u32,
    tool_registry: Option<&H::ToolRegistry>,
) -> TurnLoopToolPhaseOutcome {
    let tool_exec_lock = host.tool_exec_lock();
    let mcp_pool = host.ensure_mcp_pool_for_tools(tool_uses).await;

    let defer_set_area_batch_count = tool_uses
        .iter()
        .filter(|tool| {
            tool.name == "scratchpad_set_area"
                && tool.input.get("status").and_then(serde_json::Value::as_str) == Some("deferred")
        })
        .count();

    let mut plans: Vec<ToolExecutionPlan> = Vec::with_capacity(tool_uses.len());
    for (index, tool) in tool_uses.iter_mut().enumerate() {
        let tool_id = tool.id.clone();
        let mut tool_name = tool.name.clone();
        let tool_input = tool.input.clone();
        let tool_caller = tool.caller.clone();

        tracing::info!("Planning tool '{}' with input: {:?}", tool_name, tool_input);

        let interactive = (tool_name == "exec_shell"
            && tool_input
                .get("interactive")
                .and_then(serde_json::Value::as_bool)
                == Some(true))
            || tool_name == REQUEST_USER_INPUT_NAME;

        let mut approval_required = false;
        let mut approval_description = "Tool execution requires approval".to_string();
        let mut supports_parallel = false;
        let mut read_only = false;
        let mut blocked_error: Option<ToolError> = None;
        let mut guard_result: Option<ToolResult> = None;

        if host.maybe_activate_deferred_tool(&tool_name, tool_catalog, active_tool_names) {
            let _ = host
                .tx_event()
                .send(crate::events::Event::status(format!(
                    "Auto-loaded deferred tool '{tool_name}' after model request."
                )))
                .await;
            emit_kernel_event(
                host,
                KernelEvent::DeferredToolActivated {
                    turn_id: turn.id.clone(),
                    step_idx: turn.step,
                    tool_name: tool_name.clone(),
                },
            );
        }

        let mut tool_def = tool_catalog.iter().find(|def| def.name == tool_name);

        if tool_def.is_none()
            && let Some(canonical) =
                host.resolve_hallucinated_tool_name(&tool_name, tool_catalog, tool_registry)
        {
            tracing::info!(
                "Resolved hallucinated tool name '{}' -> '{}'",
                tool_name,
                canonical
            );
            tool_def = tool_catalog.iter().find(|d| d.name == canonical);
            if tool_def.is_some() {
                tool_name = canonical;
                tool.name = tool_name.clone();
                if host.maybe_activate_deferred_tool(&tool_name, tool_catalog, active_tool_names) {
                    emit_kernel_event(
                        host,
                        KernelEvent::DeferredToolActivated {
                            turn_id: turn.id.clone(),
                            step_idx: turn.step,
                            tool_name: tool_name.clone(),
                        },
                    );
                    let _ = host
                        .tx_event()
                        .send(crate::events::Event::status(format!(
                            "Auto-loaded deferred tool '{}' after resolving '{}'.",
                            tool_name, tool_name
                        )))
                        .await;
                }
            }
        }

        if !caller_allowed_for_tool(tool_caller.as_ref(), tool_def) {
            blocked_error = Some(ToolError::permission_denied(format!(
                "Tool '{tool_name}' does not allow caller '{}'",
                caller_type_for_tool_use(tool_caller.as_ref())
            )));
        }

        if blocked_error.is_none()
            && tool_def.is_none()
            && !host.is_mcp_tool_name(&tool_name)
            && tool_name != CODE_EXECUTION_TOOL_NAME
            && !is_tool_search_tool(&tool_name)
        {
            blocked_error = Some(ToolError::not_available(missing_tool_error_message(
                &tool_name,
                tool_catalog,
            )));
        }

        if blocked_error.is_none() {
            let meta = host.tool_plan_approval_meta(&tool_name, &tool_input, tool_registry);
            approval_required = meta.approval_required;
            approval_description = meta.approval_description;
            supports_parallel = meta.supports_parallel;
            read_only = meta.read_only;
        }

        if blocked_error.is_none()
            && tool_name == "scratchpad_set_area"
            && tool_input.get("status").and_then(serde_json::Value::as_str) == Some("deferred")
            && let Some(err) = scratchpad_defer_set_area_batch_error(defer_set_area_batch_count)
        {
            blocked_error = Some(err);
            emit_kernel_event(
                host,
                KernelEvent::LoopGuardTriggered {
                    turn_id: turn.id.clone(),
                    call_id: tool_id.clone(),
                    reason: "deferred_set_area_batch".into(),
                },
            );
        }

        if blocked_error.is_none()
            && let AttemptDecision::Block(message) =
                loop_guard.record_attempt(&tool_name, &tool_input)
        {
            tracing::warn!("{}", message);
            emit_kernel_event(
                host,
                KernelEvent::LoopGuardTriggered {
                    turn_id: turn.id.clone(),
                    call_id: tool_id.clone(),
                    reason: "identical_tool_call".into(),
                },
            );
            guard_result = Some(
                ToolResult::success(message)
                    .with_metadata(json!({"loop_guard": "identical_tool_call"})),
            );
        }

        plans.push(ToolExecutionPlan {
            index,
            id: tool_id,
            name: tool_name,
            input: tool_input,
            caller: tool_caller,
            interactive,
            approval_required,
            approval_description,
            supports_parallel,
            read_only,
            blocked_error,
            guard_result,
        });
    }

    for plan in &plans {
        emit_kernel_event(
            host,
            KernelEvent::ToolCallPlanned {
                turn_id: turn.id.clone(),
                step_idx: turn.step,
                call_id: plan.id.clone(),
                tool_name: plan.name.clone(),
                input_json: serde_json::to_string(&plan.input).unwrap_or_else(|_| "{}".into()),
                decision: PolicyDecision::new(
                    plan.approval_required,
                    plan.supports_parallel,
                    plan.read_only,
                ),
            },
        );
        emit_kernel_event(
            host,
            KernelEvent::ToolCallStarted {
                turn_id: turn.id.clone(),
                call_id: plan.id.clone(),
                wave_idx: 0,
            },
        );
    }

    let outcomes = host
        .execute_tool_plans(
            mode,
            plans,
            tool_catalog,
            active_tool_names,
            tool_registry,
            mcp_pool.clone(),
            tool_exec_lock.clone(),
        )
        .await;

    let mut step_error_count = 0usize;
    let mut step_error_categories = Vec::new();
    let mut stop_after_plan_tool = false;
    let mut loop_guard_halt: Option<String> = None;

    for outcome in outcomes {
        let duration = outcome.started_at.elapsed();
        let tool_input = outcome.input.clone();
        let tool_name_for_ws = outcome.name.clone();
        let mut tool_call =
            TurnToolCall::new(outcome.id.clone(), outcome.name.clone(), outcome.input);
        let should_stop_this_turn =
            should_stop_after_plan_tool(mode == TurnLoopMode::Plan, &outcome.name, &outcome.result);
        let session_content_for_log;

        match outcome.result {
            Ok(output) => {
                host.record_scratchpad_tool_outcome(&outcome.name, output.success);
                let mut result_text = output.content.clone();
                host.record_long_horizon_tool_outcome(
                    &outcome.name,
                    &tool_input,
                    &result_text,
                    output.success,
                )
                .await;
                if let Some(suffix) = host.take_long_horizon_tool_suffix() {
                    result_text.push_str(&suffix);
                }
                if output.success && is_audit_scratchpad_bind_tool(&outcome.name) {
                    host.on_audit_scratchpad_bind_success(
                        mode,
                        &outcome.name,
                        tool_catalog,
                        active_tool_names,
                    );
                }
                match loop_guard.record_outcome(&outcome.name, output.success) {
                    OutcomeDecision::Continue => {}
                    OutcomeDecision::Warn(message) => {
                        tracing::warn!("{}", message);
                        let _ = host
                            .tx_event()
                            .send(crate::events::Event::status(message))
                            .await;
                    }
                    OutcomeDecision::Halt(message) => {
                        emit_kernel_event(
                            host,
                            KernelEvent::LoopGuardTriggered {
                                turn_id: turn.id.clone(),
                                call_id: outcome.id.clone(),
                                reason: "failure_halt".into(),
                            },
                        );
                        loop_guard_halt.get_or_insert(message);
                    }
                }
                // A successful file-mutating tool changed the workspace, so a
                // subsequently repeated identical verify/read call is no longer a
                // redundant loop — clear the identical-call block (see
                // `LoopGuard::note_state_changed`).
                if output.success && LoopGuard::is_state_mutating_tool(&outcome.name) {
                    loop_guard.note_state_changed();
                }
                emit_tool_audit(json!({
                    "event": "tool.result",
                    "tool_id": outcome.id.clone(),
                    "tool_name": outcome.name.clone(),
                    "success": output.success,
                }));
                let workspace = host.workspace().to_path_buf();
                let session_model = host.session_mut().model.clone();
                let mut output_for_model = output.clone();
                output_for_model.content = result_text.clone();
                let output_for_context = compact_tool_result_for_context(
                    &session_model,
                    &outcome.name,
                    &output_for_model,
                );
                let output_content = result_text;

                tool_call.set_result(output_content.clone(), duration);
                host.session_mut().working_set.observe_tool_call(
                    &tool_name_for_ws,
                    &tool_input,
                    Some(&output_for_context),
                    &workspace,
                );

                if output.success {
                    host.run_post_edit_lsp_hook(&outcome.name, &tool_input)
                        .await;
                }

                session_content_for_log = output_for_context.clone();
                host.add_session_message(Message {
                    role: "user".to_string(),
                    content: vec![ContentBlock::ToolResult {
                        tool_use_id: outcome.id.clone(),
                        content: output_for_context.clone(),
                        is_error: None,
                        content_blocks: None,
                    }],
                })
                .await;
            }
            Err(e) => {
                match loop_guard.record_outcome(&outcome.name, false) {
                    OutcomeDecision::Continue => {}
                    OutcomeDecision::Warn(message) => {
                        tracing::warn!("{}", message);
                        let _ = host
                            .tx_event()
                            .send(crate::events::Event::status(message))
                            .await;
                    }
                    OutcomeDecision::Halt(message) => {
                        emit_kernel_event(
                            host,
                            KernelEvent::LoopGuardTriggered {
                                turn_id: turn.id.clone(),
                                call_id: outcome.id.clone(),
                                reason: "failure_halt".into(),
                            },
                        );
                        loop_guard_halt.get_or_insert(message);
                    }
                }
                let envelope: ErrorEnvelope = e.clone().into();
                emit_tool_audit(json!({
                    "event": "tool.result",
                    "tool_id": outcome.id.clone(),
                    "tool_name": outcome.name.clone(),
                    "success": false,
                    "error": e.to_string(),
                    "category": envelope.category.to_string(),
                    "severity": envelope.severity.to_string(),
                }));
                step_error_count += 1;
                step_error_categories.push(envelope.category);
                let error = format_tool_error(&e, &outcome.name);
                tool_call.set_error(error.clone(), duration);
                let session_error_content = format!("Error: {error}");
                let workspace = host.workspace().to_path_buf();
                host.session_mut().working_set.observe_tool_call(
                    &tool_name_for_ws,
                    &tool_input,
                    Some(&error),
                    &workspace,
                );
                session_content_for_log = session_error_content.clone();
                host.add_session_message(Message {
                    role: "user".to_string(),
                    content: vec![ContentBlock::ToolResult {
                        tool_use_id: outcome.id.clone(),
                        content: session_error_content,
                        is_error: Some(true),
                        content_blocks: None,
                    }],
                })
                .await;
            }
        }

        // Phase 3a double-write: ToolCallFinished.
        {
            let wrote = tool_writes_state(&tool_call.name);
            let kernel_outcome = if tool_call.result.is_some() {
                KernelToolOutcome::Success
            } else {
                KernelToolOutcome::ToolError {
                    message: tool_call.error.clone().unwrap_or_default(),
                }
            };
            let result_preview = tool_call
                .result
                .as_deref()
                .or(tool_call.error.as_deref())
                .map(|text| summarize_text(text, 512))
                .unwrap_or_default();
            emit_kernel_event(
                host,
                KernelEvent::ToolCallFinished {
                    turn_id: turn.id.clone(),
                    call_id: tool_call.id.clone(),
                    tool_name: tool_call.name.clone(),
                    outcome: kernel_outcome,
                    duration_ms: tool_call
                        .duration
                        .map(|d| d.as_millis() as u32)
                        .unwrap_or(0),
                    wrote_state: wrote,
                    result_preview,
                    session_content: session_content_for_log,
                },
            );
        }

        turn.record_tool_call(tool_call);
        stop_after_plan_tool |= should_stop_this_turn;
    }

    let mut outcome = TurnLoopToolPhaseOutcome {
        step_error_count,
        step_error_categories,
        break_outer_loop: stop_after_plan_tool || loop_guard_halt.is_some(),
        loop_guard_halted: loop_guard_halt.is_some(),
        continue_outer_loop: false,
    };
    if let Some(message) = loop_guard_halt {
        tracing::warn!("{}", message);
        let _ = host
            .tx_event()
            .send(crate::events::Event::status(message))
            .await;
    }
    outcome.continue_outer_loop = host
        .run_capacity_post_tool_checkpoint(
            turn,
            mode,
            tool_registry,
            tool_exec_lock,
            mcp_pool,
            step_error_count,
            consecutive_tool_error_steps,
        )
        .await;
    outcome
}