Migrate SessionPrompt to the Effect service pattern (Interface, Service,
Layer, InstanceState, makeRuntime + async facades).
Key design decisions:
- Fiber-based cancellation replaces manual AbortController management.
Effect.promise((signal) => ...) derives AbortSignals automatically;
cancel() interrupts fibers and signals propagate to the AI SDK,
shell processes, and tool execution.
- Deferred queue replaces Promise callback queue. Concurrent loop()
callers get a Deferred that resolves when the running fiber finishes.
On cancel or error, queued callers now receive proper errors instead
of hanging forever.
- Separate loops/shells maps in InstanceState replace the single shared
state object, with shell-to-loop handoff preserved: if callers queue
a loop while a shell is running, shellE cleanup starts the loop.
- Heavy helper functions (createUserMessage, handleSubtask, shellImpl,
resolveCommand, insertReminders, ensureTitle) stay as plain async
functions called via Effect.promise, keeping the migration incremental.
- resolveTools and createStructuredOutputTool are unchanged (deeply tied
to AI SDK tool callbacks).
Kit Langton
5719a13cbf