docs(spec): name the deferred id-space decision (#16134) at the rule's scope boundary

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T6HeZvT9wdSJD1ZxJb5Eno

Author: claude

.changeset/flow-node-id-uniqueness.md

@@ -43,7 +43,7 @@ every other refusal are untouched; a flow with unique top-level node ids
 parses exactly as before. The rule judges the flow's **own top-level**
 `nodes[]` only — a region body's nodes remain `analyzeRegion`'s to judge, and
 whether a region node may reuse a top-level node id (one id space or two) is a
-separate decision this change neither takes nor pre-empts.
+separate decision (#16134) this change neither takes nor pre-empts.
 
 The shape that is refused, and what the author does about it — a four-node
 excerpt, the later node renamed and its edge re-pointed:

packages/spec/src/automation/flow.test.ts

@@ -2124,9 +2124,10 @@ describe('FlowSchema — top-level node ids are unique (#15713)', () => {
   // Scope boundary, pinned so the rule cannot silently widen: it judges the
   // flow's OWN top-level `nodes[]`. A region body (`loop.config.body.nodes`) is
   // `analyzeRegion`'s to judge, at `registerFlow()`, and whether a region node
-  // may reuse a top-level id — one id space or two — is an open decision that
-  // this rule neither takes nor pre-empts. This pin records today's accept set
-  // at that boundary; the decision, when taken, moves it deliberately.
+  // may reuse a top-level id — one id space or two — is an open decision
+  // (#16134) that this rule neither takes nor pre-empts. This pin records
+  // today's accept set at that boundary; the decision, when taken, moves it
+  // deliberately.
   it('judges the top-level nodes[] only — a region node reusing a top-level id is outside this rule', () => {
     const result = FlowSchema.safeParse(flowWith([
       { id: 'start', type: 'start', label: 'Start' },

packages/spec/src/automation/flow.zod.ts

@@ -934,7 +934,7 @@ export const FlowSchema = lazySchema(() => strictObject(
   // in `control-flow.zod.ts`, at `registerFlow()`); the flow's own top-level
   // `nodes[]` parsed with the collision intact. This pass judges the top-level
   // array ALONE: a region's nodes are judged by `analyzeRegion`, and whether the
-  // two spaces are one is a separate decision, not taken here.
+  // two spaces are one is a separate decision (#16134), not taken here.
   const firstNodeIndexById = new Map<string, number>();
   flow.nodes.forEach((node, index) => {
     const first = firstNodeIndexById.get(node.id);