Module reactor 

The runtime state + event loop: one single-threaded reactor over child frames, reaped children, executor results, timers, the durable inbox and signals.

State mutation happens only here. Being the single writer is what makes the rest of the runtime reasonable about: no lock ordering, no torn reads, and an answer computed for one caller is computed against one consistent view. Every mutation is followed by a checkpoint decision, so durable state never trails the in-memory state by more than one loop turn.

The other runtime::* modules add impl Runtime blocks for turns, tools, steps and subagents; this file owns construction, the loop, lifecycle and the status view.

Structs

Counters

Counters for status/reports.

Instruction

The instruction in force. version increments on every change, so a consumer can tell a re-read from a genuinely new instruction.

PendingTool

A deferred internal-tool request (answered when its wait resolves).

Runtime

SubagentRecord

A subagent registry record, persisted as subagent/<handle> so a child’s identity and result outlive both the child and this process.

TurnJob

A queued root/conversation turn, waiting for a worker slot and for its context to be free. One context runs at most one turn at a time, so turns for the same conversation queue behind each other rather than interleaving into the same history.

Enums

PendingKind

Target

Who receives a deferred tool’s answer.

Constants

ABANDON_GRACE

Extra grace after the drain deadline before children are abandoned.

TICK

The reactor tick.

Functions

run_exit_code

Map a finished run’s status onto a process exit code, so a caller can tell how a job ended without parsing its output: refusal, budget exhaustion, a missed deadline and an unreachable model each get their own code, and anything still unfinished reports as partial.