Module engine 

Session and turn loop boundaries (P2 PR2–PR4).

Session and related state live here. The live Engine / turn_loop implementation is in zagens-core; the sidecar provides host adapters.

PR3: StartTurnParams + TurnEnginePort — RuntimeThreadManager::start_turn validates and delegates through core before sending Op::SendMessage.

Re-exports

pub use crate::session::Session;

pub use crate::session::SessionUsage;

pub use crate::turn::TurnContext;

pub use crate::turn::TurnLoopMode;

pub use crate::turn::TurnOutcomeStatus;

pub use approval::ApprovalDecision;

pub use approval::ApprovalResult;

pub use approval::UserInputDecision;

pub use approval::await_tool_approval;

pub use approval::recv_user_input_for_tool;

pub use context::COMPACTION_SUMMARY_MARKER;

pub use context::MAX_CONTEXT_RECOVERY_ATTEMPTS;

pub use context::MIN_RECENT_MESSAGES_TO_KEEP;

pub use context::TURN_MAX_OUTPUT_TOKENS;

pub use context::compact_tool_result_for_context;

pub use context::context_input_budget;

pub use context::count_oldest_messages_to_drain;

pub use context::effective_max_output_tokens;

pub use context::estimate_input_tokens_conservative;

pub use context::extract_compaction_summary_prompt;

pub use context::is_context_length_error_message;

pub use context::summarize_text;

pub use context::turn_response_headroom_tokens;

pub use context_snapshot::ThreadContextSnapshot;

pub use dispatch::ToolParallelPlanFlags;

pub use dispatch::caller_allowed_for_tool;

pub use dispatch::caller_type_for_tool_use;

pub use dispatch::final_tool_input;

pub use dispatch::format_tool_error;

pub use dispatch::is_mcp_tool_name;

pub use dispatch::mcp_tool_approval_description;

pub use dispatch::mcp_tool_is_parallel_safe;

pub use dispatch::mcp_tool_is_read_only;

pub use dispatch::parse_parallel_tool_calls;

pub use dispatch::parse_tool_input_json;

pub use dispatch::should_force_update_plan_first;

pub use dispatch::should_parallelize_tool_batch;

pub use dispatch::should_stop_after_plan_tool;

pub use handle::EngineHandle;

pub use host_bundle::EngineHostBundle;

pub use hosts::LspHost;

pub use hosts::McpHost;

pub use hosts::SandboxHost;

pub use hosts::SeamError;

pub use hosts::SeamHost;

pub use hosts::ShellHost;

pub use hosts::SubAgentHost;

pub use hosts::TopicMemoryHost;

pub use hosts::WorkshopHost;

pub use loop_guard::AttemptDecision;

pub use loop_guard::LoopGuard;

pub use loop_guard::OutcomeDecision;

pub use lsp_edit_paths::edited_paths_for_tool;

pub use lsp_edit_paths::parse_patch_paths;

pub use op::Op;

pub use runtime::Engine;

pub use scratchpad_state::ScratchpadStepState;

pub use start_turn::StartTurnParams;

pub use streaming::ContentBlockKind;

pub use streaming::FAKE_WRAPPER_NOTICE;

pub use streaming::MAX_STREAM_ERRORS_BEFORE_FAIL;

pub use streaming::MAX_TRANSPARENT_STREAM_RETRIES;

pub use streaming::STREAM_CHUNK_TIMEOUT_SECS;

pub use streaming::STREAM_MAX_CONTENT_BYTES;

pub use streaming::STREAM_MAX_DURATION_SECS;

pub use streaming::TOOL_CALL_END_MARKERS;

pub use streaming::TOOL_CALL_START_MARKERS;

pub use streaming::ToolUseState;

pub use streaming::contains_fake_tool_wrapper;

pub use streaming::filter_tool_call_delta;

pub use streaming::should_transparently_retry_stream;

pub use subagent_port::SubAgentSpawnPort;Deprecated

pub use subagent_port::SubAgentSpawnError;

pub use subagent_port::SubAgentSpawnOutcome;

pub use tool_bridge::function_call_to_tool_error;

pub use tool_bridge::tool_call_input;

pub use tool_bridge::tool_name_is_mutating;

pub use tool_bridge::tool_output_to_result;

pub use tool_bridge::tool_result_to_output;

pub use tool_bridge::value_to_tool_call;

pub use tool_catalog::CODE_EXECUTION_TOOL_NAME;

pub use tool_catalog::MULTI_TOOL_PARALLEL_NAME;

pub use tool_catalog::REQUEST_USER_INPUT_NAME;

pub use tool_catalog::TOOL_SEARCH_BM25_NAME;

pub use tool_catalog::active_tools_for_step;

pub use tool_catalog::apply_mcp_tool_deferral;

pub use tool_catalog::apply_native_tool_deferral;

pub use tool_catalog::build_model_tool_catalog;

pub use tool_catalog::ensure_advanced_tooling;

pub use tool_catalog::execute_tool_search;

pub use tool_catalog::initial_active_tools;

pub use tool_catalog::is_tool_search_tool;

pub use tool_catalog::maybe_activate_requested_deferred_tool;

pub use tool_catalog::missing_tool_error_message;

pub use tool_catalog::should_default_defer_tool;

pub use tool_progress::emit_tool_audit;

pub use tool_progress::tool_progress_opening_line;

pub use tool_progress::tool_progress_phase_line;

pub use turn_loop::McpPoolPort;

pub use turn_loop::ToolExecOutcome;

pub use turn_loop::ToolExecutionPlan;

pub use turn_loop::ToolPlanApprovalMeta;

pub use turn_loop::TurnLoopConfigView;

pub use turn_loop::TurnLoopControl;

pub use turn_loop::TurnLoopHost;

pub use turn_loop::TurnLoopStreamingPhaseOutcome;

pub use turn_loop::TurnLoopToolExec;

pub use turn_loop::TurnLoopToolExecutor;

pub use turn_loop::TurnLoopToolPhaseOutcome;

pub use turn_loop::TurnLoopToolRegistry;

pub use turn_loop::build_edit_file_approval_desc;

pub use turn_loop::handle_deepseek_turn;

pub use turn_loop::messages_with_turn_metadata;

pub use turn_loop::resolve_auto_effort;

Modules

approval

Tool-approval and user-input handshake for the agent loop (P2 PR4 → zagens-core).

config

Engine configuration — lean subset that depends only on core types (M2 strangler step of the Engine struct → zagens-core migration).

context

Context budgeting and prompt-shaping helpers for the engine (P2 PR4).

context_snapshot

Thread-level context usage snapshot — pure data type (M1 → zagens-core).

dispatch

Tool-input parsing and batch policy helpers (P2 PR4).

handle

Engine handle — outbound channel set used by the UI/runtime to drive the engine (M1 → zagens-core).

host_bundle

Host bundle for super::runtime::Engine::with_hosts (M7).

hosts

Subsystem host traits — the engine boundary for tui-owned subsystems.

loop_guard

Pure-data guardrails for repeated tool-call loops (P2 PR4 → zagens-core).

lsp_edit_paths

Pure helpers for post-edit LSP path extraction (P2 tool_execution portization).

op

Operations submitted by the UI/runtime layer to the engine (M1 → zagens-core).

op_loop

Core engine event loop (Op dispatch).

platform_ext

Platform extension port for tui-specific op dispatch (M8).

runtime

Core Engine struct (M7 strangler step).

runtime_new

Engine construction (Engine::with_hosts, M7).

scratchpad_state

Per-step scratchpad nudge state (B3/B4/B3b/C0/C1 audit scratchpad engine hooks).

start_turn

Normalized start-turn payload (P2 PR3).

streaming

Streaming response state and guardrails (P2 PR4 → zagens-core).

subagent_port

Sub-agent spawn outcome / error types (P2 tool_execution portization).

tool_bridge

ToolCall ↔ registry/ToolResult conversions for EngineToolDispatch (P2 PR4).

tool_catalog

Deferred tool catalog policy and built-in tool-search helpers (P2 PR4).

tool_parser

Legacy parser for text-based tool calls from DeepSeek models.

tool_progress

Tool progress copy and optional JSONL audit logging (P2 PR4 → zagens-core).

turn_loop

Turn loop (P2 PR4/PR6): handle_deepseek_turn, streaming + tool planning/outcomes in core; tool execution L2 in tui (tool_plans_exec).

Traits

EngineToolDispatch

Minimal tool surface required by Engine / turn_loop.

TurnEnginePort

Minimal surface RuntimeThreadManager needs to drive a turn.