3783f3e178
closeStep() previously caught and silently swallowed a throw from
agent/step-end emit. In the normal no-tool/no-steering path, this
caused runTurn to reach closeTurn(true) with reason still
{kind:completed}, so the session recorded a completed turn with
zero error events — even though a plugin had failed at a loop
boundary. This violates the contract that a throwing plugin is
contained as a turn error, not a silent success.
Now the catch calls failTurn(toError(error)), which appends the
single error event and sets reason={kind:error,…}. failTurn is
idempotent (errorReported guard), so existing error paths that
call failTurn after closeStep are unaffected.
Add regression test: a throwing agent/step-end listener during a
successful step now produces exactly one error event, a turn/end
with reason error, balanced boundaries (step/end before turn/end),
and a surviving loop.
dsh-agent-loop
THE concrete agent plugin: LoopAgent and the loop driver. Implements the Agent interface and drives the session/turn/step lifecycle.
This is the only package in the harness that contains concrete loop logic. Everything else is an abstract service or a plugin against extension seams — new behavior goes into plugins, not here.
Service: AgentLoop (ctx key: agentLoop)
Public API
ctx.agentLoop.create(id: string, options?: AgentOptions): LoopAgentCreate an agent, start its loop, and register it inctx.agents. Disposed with the calling fiber.
Injected services
agents, sessions, llm, tools, systemPrompt — all five interface services.
Configuration (schemastery)
interface Config {
agents: Array<{
id: string // required
model?: string
systemPrompt?: string
}>
}
Agents listed in config are auto-created at startup.
Classes
LoopAgent— the concreteAgentimplementation. Owns the inbox (Inbox), the per-stepAbortController, and the loop driver. Everything observable happens through session events and theagent/*event taxonomy.Inbox— per-agent queued + steering FIFOs (enqueue,steer,drainQueued,drainSteering,waitForQueued).
Loop lifecycle (loop.ts)
One invocation of runLoop() drives one agent for its whole lifetime:
forever:
wait for queued messages (idle)
TURN (error-contained):
drain queued → session('user/message') → 'turn/start'
STEP loop:
drain steering
assembly = systemPrompt.assemble()
request = waterfall agent/request
stream llm.stream(request) → session('assistant/chunk')
message = waterfall agent/step-result
session('assistant/message')
each tool-call: session('tool/call') → tools.execute() → session('tool/result')
drain steering → session('steering/message')
cont = waterfall agent/turn-continuation
if !cont: break
session('turn/end')
await session/flush
re-enqueue leftover steering as queued
idle unless more queued
Error containment: a throwing plugin ends the turn, never the loop. Dispose mid-turn emits agent/status('disposed') and ends with reason disposed.
What is NOT here
Everything that goes beyond "call the model, run the tools, repeat" belongs to plugins listening on the event taxonomy:
- Hooks:
agent/request,agent/step-result,tools/execute,agent/turn-continuation - Compaction:
agent/request - Sandbox, permission, plan mode:
tools/execute - Sub-agents: TODO seam on
AgentLoop.create() - Persistence:
session/event+session/flush - UI:
agent/stream-chunk+agent/*events