giles 8b3d92ed5f fed-sx-types Phase 5: flow-on-erlang engine core (next/flow/) ...

A native Erlang-on-SX durable workflow engine, so the fed-sx kernel can
fan activities out into business flows in its own runtime — no cross-
guest FFI to the Scheme lib/flow, no marshalling, no Scheme dependency.
The seed of a real engine (chosen over bridging Scheme flow) that can
later supersede it for substrate use.

- flow.erl — the deterministic-replay driver. Same durability model as
  the Scheme engine (re-run from the top; effects go through suspend;
  the replay log is plain [{Tag,Value}] data, restart-ready), but
  adapted to three hard runtime constraints: no re-enterable
  continuation, no process dictionary, and a blocking receive inside a
  `try` deadlocks the cooperative scheduler. Resolution: thread the log
  through a railway-style context and make suspend SHORT-CIRCUIT (like a
  fail value) instead of throwing — purely functional, sidesteps all
  three. Ctx = {flow_cont,V,Log} | {flow_susp,Tag,Log}.
- flow_spec.erl — combinator algebra mirrored from lib/flow/spec.sx:
  leaves, sequence/parallel/map_flow, flow_while/flow_until, branch,
  railway fail/recover/attempt, tap, try_catch/retry.
- flow_store.erl — durable gen_server: named-flow registry + instance
  table + start/resume/status. Drives the pure flow from handle_call,
  so no gen_server:call is ever inside the replay try-path.

Gate: next/flow/conformance.sh — 34/34. lib/erlang untouched (771/771).
See next/flow/README.md for the model + why railway threading.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

2026-06-30 17:51:15 +00:00

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