docs(spec,skills,adr): correct related-list docs for relatedList 'primary' (#2579 follow-up) (#2600)

- field.zod.ts: fix the `relatedList` JSDoc + describe — non-primary lists stack
  under a single shared "Related" tab; only 'primary' earns its own tab. Drops
  the stale "count-aware" wording that never shipped (we chose rule Z).
- skills/objectstack-ui: the single "Related" tab is no longer the ONLY layout —
  document `relatedList: 'primary'` as the zero-page way to promote a child table
  to its own tab; columns auto-derive from highlightFields.
- skills/objectstack-data: add the 'primary' tri-state; note columns are optional
  (derive from highlightFields), ONE related list PER FK (not one per child), and
  self-referential hierarchies.
- docs/adr/0035: update the read-side-mirror section for the tri-state, optional
  columns, and one-per-FK derivation.

Docs/description only; no behavior change.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: os-zhuang

.changeset/relatedlist-describe-fix.md

@@ -0,0 +1,5 @@
+---
+"@objectstack/spec": patch
+---
+
+Docs: correct the `Field.relatedList` JSDoc + `.describe()` to match the shipped behavior (#2579 follow-up). Non-primary related lists stack under a single shared "Related" tab and only `'primary'` earns its own tab — there is no count-based auto-split (the "count-aware" wording was a stale draft). Comment/description only; no code or behavior change.

docs/adr/0035-config-driven-master-detail.md

@@ -83,15 +83,19 @@ record detail page. Both intents live on the same relationship:
 | Side | Flag (on the child's FK field) | Effect |
 |---|---|---|
 | Write | `inlineEdit: true` | child rendered as an editable grid inside the parent's create/edit form (atomic save) |
-| Read | `relatedList` (+ `relatedListTitle` / `relatedListColumns`) | child rendered as a related list on the parent's detail page |
+| Read | `relatedList: boolean \| 'primary'` (+ `relatedListTitle` / `relatedListColumns`) | child rendered as a related list on the parent's detail page; `'primary'` promotes it to its own tab |
 
 Related lists are **shown by default** for every child relationship
 (`master_detail` and `lookup`) — owned (`master_detail`) children are ordered
-first. The flag is opt-*out*: set `relatedList: false` to suppress a noisy
-association/audit link from the detail page. `relatedListTitle` /
-`relatedListColumns` override the derived title / columns. Audit FKs
-(`created_by` / `updated_by` / `owner_id`) are skipped and children deduped to
-one related list each (first eligible FK wins).
+first. `relatedList` is tri-state (a *prominence* hint, not a layout switch —
+see ADR-0085): `false` suppresses a noisy association/audit link; `true` /
+omitted shows the child under a single shared **Related** tab; `'primary'`
+promotes the relationship to its **own tab** on the detail page. `relatedListTitle` /
+`relatedListColumns` override the derived title / columns — both optional, with
+columns auto-deriving from the child object's `highlightFields` when omitted.
+Audit FKs (`created_by` / `updated_by` / `owner_id`) are skipped; a child that
+references the parent through several FKs yields **one related list per FK**, and
+a self-referential FK surfaces a "children" list.
 
 The derivation is a pure function — `deriveRelatedLists(objectDef, objects)` in
 `@object-ui/app-shell` (`utils/deriveRelatedLists.ts`) — the read-side analogue

packages/spec/src/data/field.zod.ts

@@ -450,9 +450,9 @@ export const FieldSchema = lazySchema(() => z.object({
    * Tri-state (ADR-0085 semantic-role style — this is a PROMINENCE hint, NOT a
    * layout switch):
    *   - `false`         → suppress this child from the parent's detail page.
-   *   - `true` / absent  → shown; participates in the derived default layout
-   *                       (count-aware: few children → a tab each, many → the
-   *                       long tail collapses into a single "Related" tab).
+   *   - `true` / absent  → shown; stacks with the other non-primary children
+   *                       under a single shared "Related" tab. Only `'primary'`
+   *                       earns its own tab — there is no count-based auto-split.
    *   - `'primary'`     → CORE relationship: always surfaced prominently. The
    *                       detail renderer promotes it to its own tab regardless
    *                       of child count. This states business intent (true
@@ -462,7 +462,7 @@ export const FieldSchema = lazySchema(() => z.object({
    *                       (not a `relatedLayout` switch) is what admits it to the
    *                       object model under ADR-0085's admission test.
    */
-  relatedList: z.union([z.boolean(), z.literal('primary')]).optional().describe('Show this child collection as a related list on the parent\'s detail page (read-side mirror of inlineEdit). false = suppress; true/absent = shown in the count-aware derived default; \'primary\' = core relationship, always promoted to its own tab. Prominence intent, not a layout switch (ADR-0085).'),
+  relatedList: z.union([z.boolean(), z.literal('primary')]).optional().describe('Show this child collection as a related list on the parent\'s detail page (read-side mirror of inlineEdit). false = suppress; true/absent = shown (stacked under the shared "Related" tab); \'primary\' = core relationship, promoted to its own tab. Prominence intent, not a layout switch (ADR-0085).'),
   /** Optional section title for the detail-page related list (defaults to the child object label). */
   relatedListTitle: z.string().optional().describe('Title for the detail-page related list'),
   /** Optional explicit columns for the detail-page related list (derived from the child object when omitted). */

skills/objectstack-data/rules/relationships.md

@@ -302,22 +302,33 @@ project: {
   type: 'master_detail',
   reference: 'project',
   inlineEdit: true,                 // write side: edit inline in the Project form
-  relatedListTitle: 'Tasks',        // read side: title of the detail-page list
+  relatedList: 'primary',           // read side: promote to its OWN detail-page tab
+  relatedListTitle: 'Tasks',        // title of the detail-page list
   relatedListColumns: ['title', 'status', 'priority', 'due_date'],
 },
 
 // Suppress a noisy association from the detail page entirely:
 audit_ref: { type: 'master_detail', reference: 'invoice', relatedList: false },
 ```
 
-- `relatedList: false` — suppress this child from the parent's detail page
-  (use for chatty association/log children you don't want surfaced).
-- `relatedListTitle` / `relatedListColumns` — override the derived title /
-  columns (columns are otherwise auto-derived from the child object's fields).
-
-Audit FKs (`created_by`/`updated_by`/`owner_id`) never become related lists, and
-each child object yields at most one related list. See the objectstack-ui skill
-for the rendering side.
+`relatedList` is tri-state — a *prominence* hint, not a layout switch (ADR-0085):
+
+- `'primary'` — CORE relationship: the detail page gives it its **own tab**.
+  Every non-primary related list stacks under a single shared **Related** tab,
+  so `'primary'` is the one-word way to promote a child table to a first-class
+  tab without a custom page.
+- `false` — suppress this child from the parent's detail page (chatty
+  association/log children you don't want surfaced).
+- `true` / omitted — shown in the shared **Related** tab.
+
+`relatedListTitle` / `relatedListColumns` override the derived title / columns;
+both are optional — when omitted, columns auto-derive from the child object's
+`highlightFields` (the same source the lookup picker uses). Audit FKs
+(`created_by`/`updated_by`/`owner_id`) never become related lists. A child that
+references the parent through several FKs (e.g. `primary_account` +
+`partner_account`) yields **one related list per FK**; a self-referential FK
+(a hierarchy) surfaces a "children" list. See the objectstack-ui skill for the
+rendering side.
 
 ## Incorrect vs Correct
 

skills/objectstack-ui/SKILL.md

@@ -145,22 +145,27 @@ inline grid, not just invoices:
 **Read side — detail-page related lists.** The mirror of `inlineEdit` is the
 related list on the parent's record DETAIL page. You don't author it: every
 child relationship is shown as a related list by default (owned `master_detail`
-children first). Refine on the relationship — `relatedList: false` to suppress a
-noisy child, `relatedListTitle` / `relatedListColumns` to override title /
-columns (see objectstack-data → Relationships → Detail-page related lists).
-Authored record pages can still place an explicit `record:related_list` (or
-inline-editable `record:line_items`) when they need bespoke placement.
-
-**Related-list layout.** Every related list stacks under a single **Related**
-tab on the synthesized record detail page — that is the only built-in layout.
-The old `detail.relatedLayout` (`'stack'` | `'tabs'`) toggle — like the whole
-object-level `detail: {...}` block — was **removed** (ADR-0085): an object
-declares no per-surface layout hints. When a record's child tables deserve
-first-class navigation (their own tabs, bespoke placement), assign the object a
-**custom record Page** and lay it out explicitly with `record:related_list`
-(or inline-editable `record:line_items`) blocks. For lighter tweaks stay at the
-relationship layer: `relatedList: false` to suppress a noisy child,
-`relatedListTitle` / `relatedListColumns` to override title / columns.
+children first). Refine on the relationship:
+- `relatedList: 'primary'` — mark a CORE relationship; the detail page promotes
+  it to its **own tab** (see layout below). A *prominence* intent, not a layout
+  switch (ADR-0085).
+- `relatedList: false` — suppress a noisy child from the detail page.
+- `relatedListTitle` / `relatedListColumns` — override the derived title /
+  columns (both optional; columns otherwise auto-derive from the child object's
+  `highlightFields`). See objectstack-data → Relationships → Detail-page related lists.
+
+**Related-list layout.** On the synthesized record detail page, each
+`relatedList: 'primary'` child gets its **own tab**; every other related list
+stacks under a single shared **Related** tab. Promoting a child table to a
+first-class tab is therefore a one-word change on the relationship — no custom
+page needed. The object still declares no per-surface *layout* hints: the old
+`detail.relatedLayout` toggle and object-level `detail: {...}` block stay
+**removed** (ADR-0085); `relatedLayout: 'tabs' | 'stack'` survives only as an
+app-level default override, not an object key. For arrangements the
+relationship layer can't express — filtered splits (e.g. Open vs Closed tabs), a
+chart/report tab, exact tab ordering — assign the object a **custom record
+Page** and lay it out explicitly with `record:related_list` (or inline-editable
+`record:line_items`) blocks.
 
 ### Field Conditional Rules in Forms