@@ -0,0 +1,12 @@
+---
+'@objectstack/lint': patch
+---
+
+fix(lint): a flow node config-value finding carries the slot's key path, so Studio's Problems row selects the node
+
+Clause-②: no
+Metadata-protocol: none
+
+`validateStackExpressions` located a finding on a flow node's config value (an `expression-invalid` on an Update Records `fields` value, a node `condition`, a text slot, an undeclared config key, a `script` node with no `function`) by its `where` prose alone. The runtime authoring gate then used that prose as the finding's `path`, so a draft's `_diagnostics` entry for it could not be resolved to a node: Studio's Problems list showed the refusal but could not select or badge the node.
+
+Each such finding now also carries the slot's key path, in the spelling a flow edge's `condition` finding uses: `flows[0].nodes[1].config.fields.status` (a draft's `_diagnostics` reads `nodes.1.config.fields.status`). A `connector_action` input value is located in its own block (`flows[0].nodes[2].connectorConfig.input.customerId`). The `where` prose and the message are unchanged. As for edges, a node inside a nested region (a `loop` body) and a map-form `flows` collection have no index to spell, so their findings keep `where` alone. The CLI's `rule: … at …` line prints the key path for these findings, as it does for an edge's.
@@ -793,7 +793,8 @@ export const AUTHORING_RULES: readonly AuthoringRule[] = [
         rule: EXPRESSION_INVALID,
         where: i.where,
         // [#26858] The slot's key path where the pass spells one (a flow edge's
-        // `condition`), so a draft's `_diagnostics` can address the field.
+        // `condition`, #27828 a flow node's config value), so a draft's
+        // `_diagnostics` can address the field.
         path: i.path ?? i.where,
         // [#22161] The authored source is a QUOTE of what the author wrote, not
         // a fix, so it rides the verdict — `— source: \`…\`` is the spelling
 
@@ -75,7 +75,7 @@ describe('expression-invalid on a flow edge condition carries a key path (#26858
     for (const i of onEdge) expect(i.path).toBeUndefined();
   });
 
-  it('a finding off the edge condition gains no path', () => {
+  it('a finding off the edge condition gains no edge path (#27828: a node condition carries its node\'s)', () => {
     const issues = validateStackExpressions({
       flows: [
         flow([{ id: 'e1', source: 'start', target: 'end' }], {
@@ -87,7 +87,7 @@ describe('expression-invalid on a flow edge condition carries a key path (#26858
       ],
     });
     expect(issues.length).toBeGreaterThan(0);
-    for (const i of issues) expect(i.path).toBeUndefined();
+    for (const i of issues) expect(i.path).toBe('flows[0].nodes[0].config.condition');
   });
 
   it('reaches the publish gate: the refusal is located at the edge condition, message unchanged', () => {
 
@@ -0,0 +1,142 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * #27828 — a flow node's config-value finding carries the slot's key path.
+ *
+ * `expression-invalid` is what publish refuses a node's config value with
+ * (measured on a blank expression in an Update Records value), and its finding
+ * was located by its `where` prose alone (`flow 'f' · node 'set' (update_record)
+ * update_record field value at config.fields.status`). A draft's
+ * `_diagnostics` path was therefore that prose, so Studio's Problems row listed
+ * the refusal but could not select the node. The finding now carries the key
+ * path in the spelling the edge findings use since #26858
+ * (`flows[0].nodes[1].config.fields.status`) beside the unchanged `where` and
+ * message.
+ */
+
+import { describe, expect, it } from 'vitest';
+
+import { runRuntimeAuthoringRules } from './runtime-gate.js';
+import { validateStackExpressions } from './validate-expressions.js';
+import type { ExprIssue } from './validate-expressions.js';
+
+type AnyRec = Record<string, unknown>;
+
+const BLANK = { dialect: 'cel', source: '   ' };
+
+const START = { id: 'start', type: 'start', label: 'Start' };
+const END = { id: 'end', type: 'end', label: 'End' };
+
+/** An Update Records node whose `status` value is a blank CEL envelope. */
+const SET = {
+  id: 'set',
+  type: 'update_record',
+  label: 'Set',
+  config: { objectName: 'task', filter: { id: 'x' }, fields: { title: 'kept', status: BLANK } },
+};
+
+function flow(nodes: unknown[], extra: AnyRec = {}): AnyRec {
+  return {
+    name: 'node_cfg',
+    label: 'Node config',
+    type: 'autolaunched',
+    nodes,
+    edges: [
+      { id: 'e1', source: 'start', target: 'set' },
+      { id: 'e2', source: 'set', target: 'end' },
+    ],
+    ...extra,
+  };
+}
+
+const onNode = (issues: ExprIssue[], id: string) => issues.filter((i) => i.where.includes(`node '${id}'`));
+
+describe('a flow node config-value finding carries a key path (#27828)', () => {
+  it('names the node by its index in the authored list, where and message unchanged', () => {
+    const issues = onNode(validateStackExpressions({ flows: [flow([START, SET, END])] }), 'set');
+    expect(issues.length).toBeGreaterThan(0);
+    for (const i of issues) {
+      expect(i.path).toBe('flows[0].nodes[1].config.fields.status');
+      expect(i.where).toBe("flow 'node_cfg' · node 'set' (update_record) update_record field value at config.fields.status");
+    }
+  });
+
+  it('indexes the raw list: a null member before the node does not renumber it', () => {
+    const issues = onNode(validateStackExpressions({ flows: [flow([START, null, SET, END])] }), 'set');
+    expect(issues.length).toBeGreaterThan(0);
+    for (const i of issues) expect(i.path).toBe('flows[0].nodes[2].config.fields.status');
+  });
+
+  it('indexes the flow in the stack', () => {
+    const clean = { ...flow([START, END]), name: 'clean', edges: [{ id: 'e1', source: 'start', target: 'end' }] };
+    const issues = onNode(validateStackExpressions({ flows: [clean, flow([START, SET, END])] }), 'set');
+    expect(issues.length).toBeGreaterThan(0);
+    for (const i of issues) expect(i.path).toBe('flows[1].nodes[1].config.fields.status');
+  });
+
+  it('every node-config arm locates its finding at the slot it judged', () => {
+    const nodes = [
+      { ...START, config: { condition: 'record.name ==' } },
+      // A value slot's retired single-brace token (the template-refusal arm).
+      { id: 'tok', type: 'update_record', label: 'Tok', config: { objectName: 'task', filter: { id: 'x' }, fields: { title: '{record.name}' } } },
+      // A text slot's single-brace token (the text-slot arm).
+      { id: 'say', type: 'notify', label: 'Say', config: { recipients: ['a@b.c'], title: 'Hi {record.name}', message: 'ok' } },
+      // A key the node's contract does not declare (the config-refusal arm).
+      { id: 'odd', type: 'notify', label: 'Odd', config: { bogusKey: 1, recipients: ['a@b.c'], title: 'ok', message: 'ok' } },
+      // A script with no callable (the script arm).
+      { id: 'run', type: 'script', label: 'Run', config: {} },
+      // A sibling-block value slot (#27968): the path names its block.
+      {
+        id: 'call',
+        type: 'connector_action',
+        label: 'Call',
+        config: {},
+        connectorConfig: { connectorId: 'crm', actionId: 'push', input: { customerId: '{record.id}' } },
+      },
+    ];
+    const issues = validateStackExpressions({ flows: [flow(nodes, { edges: [] })] });
+    const pathsOf = (id: string) => [...new Set(onNode(issues, id).map((i) => i.path))];
+    expect(pathsOf('start')).toEqual(['flows[0].nodes[0].config.condition']);
+    expect(pathsOf('tok')).toEqual(['flows[0].nodes[1].config.fields.title']);
+    expect(pathsOf('say')).toEqual(['flows[0].nodes[2].config.title']);
+    expect(pathsOf('odd')).toEqual(['flows[0].nodes[3].config.bogusKey']);
+    expect(pathsOf('run')).toEqual(['flows[0].nodes[4].config.function']);
+    expect(pathsOf('call')).toEqual(['flows[0].nodes[5].connectorConfig.input.customerId']);
+  });
+
+  it('a map-form flows collection has no index to spell, so the finding keeps where alone', () => {
+    const { name: _name, ...body } = flow([START, SET, END]);
+    const issues = onNode(validateStackExpressions({ flows: { node_cfg: body } }), 'set');
+    expect(issues.length).toBeGreaterThan(0);
+    for (const i of issues) expect(i.path).toBeUndefined();
+  });
+
+  it('a node inside a nested region keeps where alone, as a nested edge does', () => {
+    const loop = {
+      id: 'each',
+      type: 'loop',
+      label: 'Each',
+      config: {
+        collection: { dialect: 'cel', source: '[1, 2]' },
+        itemVariable: 'item',
+        body: { nodes: [{ ...SET, id: 'inner' }], edges: [] },
+      },
+    };
+    const issues = onNode(
+      validateStackExpressions({ flows: [flow([START, loop, END], { edges: [{ id: 'e1', source: 'start', target: 'each' }, { id: 'e2', source: 'each', target: 'end' }] })] }),
+      'inner',
+    );
+    expect(issues.length).toBeGreaterThan(0);
+    for (const i of issues) expect(i.path).toBeUndefined();
+  });
+
+  it('reaches the publish gate: the refusal is located at the node config value, message unchanged', () => {
+    const result = runRuntimeAuthoringRules({ type: 'flow', item: flow([START, SET, END]) });
+    const refusals = result.errors.filter((f) => f.rule === 'expression-invalid');
+    expect(refusals.length).toBeGreaterThan(0);
+    for (const f of refusals) {
+      expect(f.path).toMatch(/^flows(\[0\]|\.node_cfg)\.nodes\[1\]\.config\.fields\.status$/);
+      expect(f.where).toBe("flow 'node_cfg' · node 'set' (update_record) update_record field value at config.fields.status");
+    }
+  });
+});
@@ -3624,6 +3624,10 @@ describe('validateStackExpressions — reads only keys the spec declares (meta-t
       // its `traversals` and `multiHopFields` — the formula package's own
       // result keys, never metadata keys.
       'analysis',
+      // [#27828] A node's `where` → judged key path index, filled by the
+      // node walk's own sites. Its keys are `Map.prototype.set` / `get`, never
+      // metadata keys; the config it describes is read off the tabled `cfg`.
+      'nodeSlotKeys',
     ]);
     expect(receivers.filter((r) => !tabled.has(r) && !PLUMBING.has(r))).toEqual([]);
   });
 
@@ -165,7 +165,10 @@ export interface ExprIssue {
    * [#26858] The judged slot's key path in the stack, in the spelling the other
    * rules' findings carry (`flows[0].edges[1].condition`), beside the human
    * `where`. Set only where the slot has one: a top-level flow edge's
-   * `condition`, and (#27643) an object validation rule's `condition` / `when`
+   * `condition`, (#27828) a top-level flow node's judged config value
+   * (`flows[0].nodes[1].config.fields.status`, a sibling block's
+   * `flows[0].nodes[2].connectorConfig.input.customerId`), and (#27643) an
+   * object validation rule's `condition` / `when`
    * (`objects[0].validations[1].condition`), a nested branch's included
    * (`objects[0].validations[1].then.condition`). Absent, the finding is
    * located by `where` alone.
@@ -2722,7 +2725,13 @@ export function runStackExpressionPasses(stack: AnyRec, options: StackExpression
       // that guarantee stops, through the file's one home for it.
       for (const node of recordsOf(graph.nodes)) {
         const cfg = (node.config ?? {}) as AnyRec;
+        // [#27828] Each site below names the key it judged beside its `where`;
+        // after the walk, this node's findings carry that key path (see the
+        // stamp at the end of this body).
+        const nodeFirst = issues.length;
+        const nodeSlotKeys = new Map<string, string>();
         const nodeCondWhere = `${at} · node '${node.id}' (${node.type}) condition`;
+        nodeSlotKeys.set(nodeCondWhere, 'config.condition');
         if (!checkStructuralCondition(nodeCondWhere, cfg.condition).refused) {
           const from = issues.length;
           check(nodeCondWhere, cfg.condition, objectName);
@@ -2762,8 +2771,10 @@ export function runStackExpressionPasses(stack: AnyRec, options: StackExpression
             || (configRefusal.code === 'node-config-refused-by-contract' && configRefusal.path === 'functionName')
           )));
         for (const configRefusal of configRefusals) {
+          const configWhere = `${at} · node '${node.id}' (${nodeType}) config.${configRefusal.path}`;
+          nodeSlotKeys.set(configWhere, `config.${configRefusal.path}`);
           issues.push({
-            where: `${at} · node '${node.id}' (${nodeType}) config.${configRefusal.path}`,
+            where: configWhere,
             message: configRefusal.message,
             source: configRefusal.source,
             severity: 'error',
@@ -2774,6 +2785,7 @@ export function runStackExpressionPasses(stack: AnyRec, options: StackExpression
         // `connectorConfig.input` — and names the block it is in.
         for (const found of resolveFlowNodeExpressions(nodeType, cfg, node)) {
           const slotWhere = `${at} · node '${node.id}' (${nodeType}) ${found.entry.label} at ${found.block}.${found.path}`;
+          nodeSlotKeys.set(slotWhere, `${found.block}.${found.path}`);
           // [#15137] `value` slots are checkable too, by their own rule — see
           // `checkDeclaredValue`. Not shadowing-checked: the shadow diagnostic is
           // about a bare identifier resolving to a variable instead of a field,
@@ -2832,8 +2844,10 @@ export function runStackExpressionPasses(stack: AnyRec, options: StackExpression
         // and the two legacy `assignment` shapes, so build and registration
         // give one verdict, and each refusal names the token's CEL spelling.
         for (const templateRefusal of flowNodeValueTemplateRefusals(nodeType, cfg, node)) {
+          const templateWhere = `${at} · node '${node.id}' (${nodeType}) ${templateRefusal.label} at ${templateRefusal.block}.${templateRefusal.path}`;
+          nodeSlotKeys.set(templateWhere, `${templateRefusal.block}.${templateRefusal.path}`);
           issues.push({
-            where: `${at} · node '${node.id}' (${nodeType}) ${templateRefusal.label} at ${templateRefusal.block}.${templateRefusal.path}`,
+            where: templateWhere,
             message: templateRefusal.message,
             source: templateRefusal.source,
             severity: 'error',
@@ -2850,6 +2864,7 @@ export function runStackExpressionPasses(stack: AnyRec, options: StackExpression
         // throw at the node mid-run.
         for (const slot of flowNodeTextSlotSources(nodeType, cfg)) {
           const slotWhere = `${at} · node '${node.id}' (${nodeType}) ${slot.label} at config.${slot.path}`;
+          nodeSlotKeys.set(slotWhere, `config.${slot.path}`);
           const tokenRefusal = textSlotTemplateRefusal(slot.source);
           if (tokenRefusal !== undefined) {
             issues.push({ where: slotWhere, message: tokenRefusal, source: slot.source, severity: 'error' });
@@ -2879,6 +2894,8 @@ export function runStackExpressionPasses(stack: AnyRec, options: StackExpression
           const action = typeof cfg.actionType === 'string' ? cfg.actionType.trim() : '';
           const retired = ['actionType', 'template', 'recipients', 'variables', 'script']
             .filter((k) => cfg[k] != null);
+          // The first retired key the author wrote, or the `function` to write.
+          nodeSlotKeys.set(`${at} · node '${node.id}' (script) callable`, `config.${retired[0] ?? 'function'}`);
           if (retired.length > 0) {
             issues.push({
               where: `${at} · node '${node.id}' (script) callable`,
@@ -2914,6 +2931,20 @@ export function runStackExpressionPasses(stack: AnyRec, options: StackExpression
             });
           }
         }
+        // [#27828] A top-level node's findings also carry the judged slot's key
+        // path, the #26858 edge shape (`flows[0].nodes[1].config.fields.status`),
+        // indexed over the list the author wrote (the coerced one drops `null`
+        // members and would renumber). A nested region's node keeps `where`, as
+        // its edges do.
+        const nodeIndex = flowIndex >= 0 && graph.path.length === 0 && Array.isArray(flow.nodes)
+          ? flow.nodes.indexOf(node)
+          : -1;
+        if (nodeIndex >= 0) {
+          for (let k = nodeFirst; k < issues.length; k++) {
+            const key = nodeSlotKeys.get(issues[k]!.where);
+            if (key !== undefined) issues[k] = { ...issues[k]!, path: `flows[${flowIndex}].nodes[${nodeIndex}].${key}` };
+          }
+        }
       }
       // `recordsOf`, not `as unknown as AnyRec[]` (#16910) — the same reason as
       // the `graph.nodes` reader above: a NESTED region's edge list is only
 
@@ -462,6 +462,39 @@ describe('a draft reads the verdict its publish gives (#26707)', () => {
             expect.objectContaining({ path: 'nodes.0.config.secret', code: 'flow-api-trigger-secret-missing' }),
         );
     });
+
+    it('[#27828] a node config value refused by expression-invalid is located at the node, not in where prose', async () => {
+        const { engine } = makeStubEngine();
+        const protocol = new ObjectStackProtocolImplementation(engine);
+        // Studio's Update Records value with its expression left blank.
+        const flow = {
+            name: 'blank_value',
+            label: 'Blank Value',
+            type: 'autolaunched',
+            nodes: [
+                { id: 'start', type: 'start', label: 'Start' },
+                {
+                    id: 'set',
+                    type: 'update_record',
+                    label: 'Set',
+                    config: { objectName: 'deal', filter: { id: 'x' }, fields: { name: { dialect: 'cel', source: '   ' } } },
+                },
+                { id: 'end', type: 'end', label: 'End' },
+            ],
+            edges: [
+                { id: 'e1', source: 'start', target: 'set' },
+                { id: 'e2', source: 'set', target: 'end' },
+            ],
+        };
+        await stageDraft(protocol, 'flow', flow);
+
+        const diagnostics = await draftDiagnostics(protocol, 'flow', flow.name);
+        const refused = (diagnostics.errors ?? []).filter((e) => e.code === 'expression-invalid');
+        expect(diagnostics.valid).toBe(false);
+        expect(refused.length).toBeGreaterThan(0);
+        // `nodes.<index>.…` is the spelling Studio's Problems list maps onto a node.
+        for (const e of refused) expect(e.path).toBe('nodes.1.config.fields.name');
+    });
 });
 
 describe('[#27444] an object draft without its package namespace prefix', () => {