fix(lint): searchable-fields hints prescribe a stored field, not formula (#6673) (#6921)

Both authoring-time hints for a bad `searchableFields` entry told the author
to mirror a related record's value onto a formula field — a fix that can
never work: a `formula` field is virtual (no driver materializes a column for
it), so a `$contains` predicate against one has nothing to scan, and a CEL
formula only reads the record's own fields, so it cannot fetch the related
title in the first place.

- validate-searchable-fields.ts:347 (dotted-path entry, SEARCHABLE_FIELD_UNKNOWN):
  "copy the value onto a formula field here" -> "...a stored text field here."
- validate-searchable-fields.ts:414 (lookup/master_detail outside the allowed
  set, SEARCHABLE_FIELD_UNSEARCHABLE): "mirror it onto a text/formula field"
  -> "mirror it onto a stored text field".

Matches the prescription already shipped in content/docs/data-modeling/
schema-design.mdx and the objectstack-data / objectstack-ui skills (PR #6670,
#6898) — the tool's own hint text now agrees with the corpus that quotes it.

Pinned tests strengthened to assert the new wording and reject "formula"
(reverse-verified: reverting either string to the old wording turns both
tests red).

Co-authored-by: Claude <noreply@anthropic.com>

Author: os-project-manager

.changeset/searchable-fields-stored-hint.md

@@ -0,0 +1,33 @@
+---
+"@objectstack/lint": patch
+---
+
+fix(lint): `searchable-field-unknown` / `searchable-field-unsearchable` prescribe a **stored** mirror, not a formula (#6673)
+
+Both authoring-time hints for a bad `searchableFields` entry told the author to
+mirror a related record's value onto a formula field — a fix that can never
+work:
+
+- FROM (dotted-path entry, e.g. `project_id.name`): "…expand the relation and
+  search the related object, or copy the value onto **a formula field** here."
+- TO: "…or copy the value onto **a stored text field** here."
+
+- FROM (a `lookup`/`master_detail` column outside the allowed set): "…mirror
+  it onto **a text/formula** field here and declare that instead."
+- TO: "…mirror it onto **a stored text** field here and declare that instead."
+
+A `formula` field is virtual — no driver materializes a column for it
+(`packages/objectql/src/engine.ts`, `driver-sql/src/schema-drift.ts`,
+`driver-turso/src/remote-transport.ts`), so a `$contains` predicate against one
+has nothing to scan. A CEL formula also only reads the record's own fields
+(`record.<field>`), so it cannot fetch the related title in the first place.
+Only the **stored** half of the old prescription ever worked; an author who
+followed it verbatim got metadata that passed both lint and the `#4254`
+runtime gate and then just never matched.
+
+The corpus already prescribes the stored-field mirror everywhere else
+(`content/docs/data-modeling/schema-design.mdx`, the `objectstack-data` and
+`objectstack-ui` skills, PR #6670 / #6898) — this brings the tool's own hint
+text into agreement with it.
+
+Message text only — no schema, rule id, severity, or runtime behaviour change.

packages/lint/src/validate-searchable-fields.test.ts

@@ -213,6 +213,10 @@ describe('validateSearchableFields — dotted paths', () => {
     expect(findings).toHaveLength(1);
     expect(findings[0].path).toBe('objects[0].searchableFields[1]');
     expect(findings[0].hint).toContain("scans this object's own columns");
+    // The prescription must be a STORED field — a `formula` field is virtual
+    // (no driver materializes a column for it), so it can never be scanned.
+    expect(findings[0].hint).toContain('copy the value onto a stored text field');
+    expect(findings[0].hint).not.toContain('formula');
   });
 });
 
@@ -315,8 +319,11 @@ describe('validateSearchableFields — list views that narrow the set', () => {
     expect(findings[0].message).toContain("type 'lookup'");
     expect(findings[0].message).toContain('400 INVALID_FIELD');
     // The lookup-specific prescription: search cannot cross objects, so the
-    // related record's title must be mirrored onto a local text/formula field.
+    // related record's title must be mirrored onto a local STORED text field —
+    // never a `formula` field, which is virtual and materializes no column.
     expect(findings[0].hint).toContain('mirror');
+    expect(findings[0].hint).toContain('mirror it onto a stored text field');
+    expect(findings[0].hint).not.toContain('formula');
   });
 
   it('flags a real field outside the object\'s declared searchableFields', () => {

packages/lint/src/validate-searchable-fields.ts

@@ -344,7 +344,7 @@ export function checkSearchableFieldList(
           (dotted
             ? `'search' scans this object's own columns, so a related record's ` +
               `column cannot be a search target — expand the relation and search ` +
-              `the related object, or copy the value onto a formula field here. `
+              `the related object, or copy the value onto a stored text field here. `
             : `Fix the name, or add "${name}" to ${objectName}.fields. `) +
           `Clients echo this declaration verbatim as the '$searchFields' ` +
           `override, so a stale entry becomes a 400 INVALID_FIELD on list ` +
@@ -411,7 +411,7 @@ export function checkSearchableFieldList(
         (isReference
           ? `A ${meta?.type} column stores only the referenced record's id, so it ` +
             `cannot be a keyword target — drop "${name}" from this view and, to ` +
-            `search by the related record's title, mirror it onto a text/formula ` +
+            `search by the related record's title, mirror it onto a stored text ` +
             `field here and declare that instead. `
           : `Drop "${name}" from this view, or target a text-like field instead. `) +
         `Declaring 'searchableFields' on object "${objectName}" chooses the ` +