- add_edge gains into= for named-slot fan-in; recorded ops carry it
- rule 3b at import time: multi-parent targets must fit named-slot form
  (required fields covered exactly once, source output_type fits the slot)
  or collected form (exactly one list[<model>] field, arity within its
  min_length/max_length); humans stay single-parent; mixing static parents
  with conditional dispatch is rejected as ambiguous
- validation now builds once against a throwaway StateGraph; the recording-
  sink double-build determinism check is replaced by a static lint over
  build()'s source rejecting environment/clock/random reads, mutation of
  self or module globals, and iteration over sets

@@ -0,0 +1,105 @@
+"""Workflow discovery from explicit listings.

@@ -0,0 +1,79 @@
+"""In-process registry of discovered workflow classes.
+

@@ -0,0 +1,181 @@
+"""Tests for explicit-listing workflow discovery."""

@@ -3,10 +3,10 @@
 Workflow is the single abstraction every node kind derives from; identity is
 the fully-qualified class path, so plugins never collide with core classes.

@@ -216,3 +207,1 @@
-    ) -> None:
-        targets = tuple(sorted((label, _endpoint(t)) for label, t in branches.items()))
-        self.ops.append(_Op("add_conditional", (_endpoint(src), targets)))
+_BUILDER_DOC = """