@@ -0,0 +1,20 @@
+---
+'@objectstack/lint': minor
+---
+
+**BREAKING** fix(metadata)!: a flow whose loop, parallel or try_catch region is malformed is refused at publish, and its draft read says so, instead of publishing and then never registering
+
+Clause-②: no (narrowing)
+Metadata-protocol: narrowed
+Skills-docs: none — no published skill teaches that a malformed region publishes; the automation skill's region rules (one entry, one exit, acyclic) stay true, and the publish door now refuses a region that breaks them earlier, in the engine's words.
+
+<!-- adr-0087: not-required (no-migration-prescription) No key of any schema is added, removed, renamed or re-shaped. The publish doors now refuse a flow body the automation engine already refuses to register, with the engine's own sentence, so a published body that could never run has nothing a migration could rewrite it to: the author's fix is the one the refusal names. -->
+
+**BREAKING** accept-set narrowing at the runtime authoring gate, which the metadata draft read and every publish door run (`PUT /api/v1/meta/:type/:name` live, `POST …/publish`, `POST /api/v1/packages/:id/publish-drafts`). The `@objectstack/lint` authoring rule `validateFlowRegionShape` (`flow-region-shape-invalid`), which `os validate`, `os build` and `os lint` already run, now also runs on that gate for `flow` writes (`surfaces: CLI_AND_RUNTIME`, `runtimeTypes: ['flow']`).
+
+- **Before.** A flow whose ADR-0031 region was malformed (a `loop` body, a `parallel` branch or a `try_catch` try or catch region, at any depth, with no single entry or exit node, a cycle inside it, a shape its region schema refuses, or a `parallel` block with fewer than two branches) saved as a draft, its draft read answered `_diagnostics: { valid: true }`, and it published (`outcome: 'published'`). The automation engine then refused to register it ("loop 'lp' body: region has no entry node …; region contains a cycle (region bodies must be acyclic)"), so the flow never ran, and only the by-name read's `registration` and a boot-log warning said why.
+- **Now.** The draft still saves (drafts are never gated). Its read answers `valid: false` with an error coded `flow-region-shape-invalid`, and every publish door refuses it `422 INVALID_METADATA` with that finding; a package publish refuses the batch (`outcome: 'refused'`). The message is "Flow 'NAME' would be refused at registration: " followed by the engine's registration refusal, word for word. The finding names the flow (one per flow, the engine's first refusal); the sentence names the region.
+- **One judge, one name.** The rule calls `FlowSchema`, then `validateControlFlow` (`@objectstack/spec/automation`), the two calls the engine's registration makes. A flow body the flow schema refuses is reported by this rule too ("could not be judged for its region shape"), as on the CLI.
+- **Unchanged.** A flow whose regions the engine accepts publishes and registers, as before.
+
+**The remedy.** None for a flow that registers today: it publishes exactly as before. A flow this now refuses was already refused by the engine at registration and never ran; the refusal names the region and what is wrong with it. Give the region one entry node and one exit node with no cycle inside it, and give a `parallel` block at least two branches. A stored flow published before this change is re-registered exactly as before (still refused by the engine).
@@ -1981,11 +1981,12 @@ export const AUTHORING_RULES: readonly AuthoringRule[] = [
     input: 'parsed',
     commands: ALL,
     source: 'packages/lint/src/validate-flow-region-shape.ts',
-    surfaces: CLI_ONLY,
-    surfaceReason:
-      'Not yet on the runtime publish gate: whether a flow write whose region the engine refuses is refused at '
-      + 'publish is the server lane\'s open question for the metadata write path, decided there; this entry '
-      + 'brings the three authoring commands to the engine\'s registration verdict.',
+    // [#29233] Runtime publish gate (#4463): a flow whose region the engine
+    // refuses to register can only ever publish as a flow that never runs, so
+    // the draft read and every publish door refuse it here, through this one
+    // row, rather than through a gate-local copy of the same judgement.
+    surfaces: CLI_AND_RUNTIME,
+    runtimeTypes: ['flow'],
     run: (stack) => validateFlowRegionShape(stack),
   },
   // The same predicate over a declarative connector's four header/env maps
 
@@ -21,28 +21,35 @@ import { validatePredicatePathRefs } from './validate-predicate-path-refs.js';
 import { validateWidgetBindings } from './validate-widget-bindings.js';
 
 /** The issue's measured example: an approval flow whose expression approver is broken CEL. */
+// [#29233] Spelled as a body the flow schema accepts (a `type`, node labels,
+// an edge list, no top-level `trigger`), since the publish gate now runs the
+// region-shape rule, which refuses a flow the schema refuses. Each case below
+// still isolates the one thing it pins: the approver expression.
 const brokenApprovalFlow = {
   name: 'leave_approval',
   label: 'Leave approval',
-  trigger: { type: 'record_change', object: 'leave_request', events: ['create'] },
+  type: 'autolaunched',
   nodes: [
-    { id: 'start', type: 'start' },
+    { id: 'start', type: 'start', label: 'Start' },
     {
       id: 'approve',
       type: 'approval',
+      label: 'Approve',
       config: { approvers: [{ type: 'expression', value: 'record.owner ==' }] },
     },
   ],
+  edges: [{ id: 'e1', source: 'start', target: 'approve' }],
 };
 
 /** The same flow with an approver expression that parses and uses a legal root. */
 const cleanApprovalFlow = {
   ...brokenApprovalFlow,
   nodes: [
-    { id: 'start', type: 'start' },
+    { id: 'start', type: 'start', label: 'Start' },
     {
       id: 'approve',
       type: 'approval',
+      label: 'Approve',
       config: {
         approvers: [{ type: 'expression', value: 'current.owner' }],
       },
 
@@ -1099,13 +1099,17 @@ describe('validateFlowTriggerReadiness', () => {
       config: Record<string, unknown>,
       overrides: Record<string, unknown> = {},
     ): Record<string, unknown> {
+      // [#29233] A label on the flow and its nodes: the runtime publish gate
+      // the cases below cross now runs the region-shape rule, which refuses a
+      // body the flow schema refuses.
       return {
         name: 'inbound_order',
+        label: 'Inbound order',
         type: 'api',
         status: 'active',
         nodes: [
-          { id: 'start', type: 'start', config },
-          { id: 'end', type: 'end' },
+          { id: 'start', type: 'start', label: 'Start', config },
+          { id: 'end', type: 'end', label: 'End' },
         ],
         edges: [{ id: 'e1', source: 'start', target: 'end' }],
         ...overrides,
@@ -1298,8 +1302,8 @@ describe('validateFlowTriggerReadiness', () => {
         // it `flows[0].nodes[1].config.secret`, the rule's own finding path.
         const startSecond = apiFlow({ hookId: 'intake' }, {
           nodes: [
-            { id: 'end', type: 'end' },
-            { id: 'start', type: 'start', config: { hookId: 'intake' } },
+            { id: 'end', type: 'end', label: 'End' },
+            { id: 'start', type: 'start', label: 'Start', config: { hookId: 'intake' } },
           ],
         });
         const at = (paths: string[]) =>
 
@@ -460,8 +460,57 @@ const CASES: Array<{ rule: string; type: string; item: { name: string } & Record
             ],
         },
     },
+    {
+        // [#29233] A loop whose body closes on itself (body a → b → a, the
+        // card's reproduction). It saved, read valid:true and PUBLISHED, and
+        // the engine's region check then refused to register it.
+        rule: 'flow-region-shape-invalid',
+        type: 'flow',
+        item: regionFlow('region_loop', {
+            id: 'lp',
+            type: 'loop',
+            label: 'Loop',
+            config: {
+                collection: [1, 2],
+                iteratorVariable: 'row',
+                body: {
+                    nodes: [
+                        { id: 'step_a', type: 'assignment', label: 'A' },
+                        { id: 'step_b', type: 'assignment', label: 'B' },
+                    ],
+                    edges: [
+                        { id: 'b1', source: 'step_a', target: 'step_b' },
+                        { id: 'b2', source: 'step_b', target: 'step_a' },
+                    ],
+                },
+            },
+        }),
+    },
 ];
 
+/** [#29233] start → CONTAINER → end, the container's region carrying the case. */
+function regionFlow(name: string, container: Record<string, unknown>) {
+    return {
+        name,
+        label: name,
+        type: 'autolaunched',
+        nodes: [
+            { id: 'start', type: 'start', label: 'Start' },
+            container,
+            { id: 'end', type: 'end', label: 'End' },
+        ],
+        edges: [
+            { id: 'e1', source: 'start', target: container.id as string },
+            { id: 'e2', source: container.id as string, target: 'end' },
+        ],
+    };
+}
+
+/** [#29233] One straight body of a single step, the well-formed region shape. */
+function oneStep(id: string) {
+    return { nodes: [{ id, type: 'assignment', label: id }], edges: [] };
+}
+
 /** Stage one env-wide, package-bound draft (Studio's autosave shape). */
 async function stageDraft(protocol: ObjectStackProtocolImplementation, type: string, item: { name: string }) {
     return (protocol as any).saveMetaItem({ type, name: item.name, item, packageId: PKG, mode: 'draft' });
@@ -541,6 +590,58 @@ describe('a draft reads the verdict its publish gives (#26707)', () => {
         expect(published).toMatchObject({ success: true, failedCount: 0 });
     });
 
+    it('[#29233] a well-formed loop, parallel and try_catch region each still read valid:true and publish', async () => {
+        const { engine } = makeStubEngine();
+        const protocol = new ObjectStackProtocolImplementation(engine);
+        const flows = [
+            regionFlow('ok_loop', {
+                id: 'lp', type: 'loop', label: 'Loop',
+                config: { collection: [1, 2], iteratorVariable: 'row', body: oneStep('loop_step') },
+            }),
+            regionFlow('ok_parallel', {
+                id: 'fan', type: 'parallel', label: 'Fan',
+                config: { branches: [oneStep('left_step'), oneStep('right_step')] },
+            }),
+            regionFlow('ok_try', {
+                id: 'guard', type: 'try_catch', label: 'Guard',
+                config: { try: oneStep('try_step'), catch: oneStep('catch_step') },
+            }),
+        ];
+        for (const flow of flows) await stageDraft(protocol, 'flow', flow);
+
+        for (const flow of flows) expect(await draftDiagnostics(protocol, 'flow', flow.name)).toEqual({ valid: true });
+        const published: any = await protocol.publishPackageDrafts({ packageId: PKG });
+        expect(published).toMatchObject({ success: true, publishedCount: 3, failedCount: 0 });
+    });
+
+    it('[#29233] the region verdict on the draft read is the registry rule\'s: the engine\'s sentence, at the item root', async () => {
+        const { engine } = makeStubEngine();
+        const protocol = new ObjectStackProtocolImplementation(engine);
+        // A one-branch parallel block nested in a try region. The registry rule
+        // judges the flow as one unit (as the engine does) and anchors the
+        // flow itself, so the item-relative path is the item root; the
+        // sentence names the region.
+        const flow = regionFlow('nested_region', {
+            id: 'guard', type: 'try_catch', label: 'Guard',
+            config: {
+                try: {
+                    nodes: [{ id: 'fan', type: 'parallel', label: 'Fan', config: { branches: [oneStep('only_step')] } }],
+                    edges: [],
+                },
+                catch: oneStep('catch_step'),
+            },
+        });
+        await stageDraft(protocol, 'flow', flow);
+
+        const diagnostics = await draftDiagnostics(protocol, 'flow', flow.name);
+        expect(diagnostics.valid).toBe(false);
+        expect((diagnostics.errors ?? []).filter((e) => e.code === 'flow-region-shape-invalid')).toEqual([{
+            path: '',
+            message: "Flow 'nested_region' would be refused at registration: parallel 'fan': a parallel block needs at least 2 branches",
+            code: 'flow-region-shape-invalid',
+        }]);
+    });
+
     it('[#29025] the same loop with its closing edge typed back still reads valid:true and publishes', async () => {
         const { engine } = makeStubEngine();
         const protocol = new ObjectStackProtocolImplementation(engine);