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diff --git a/‎packages/app-shell/src/views/ObjectView.tsx‎
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diff --git a/‎packages/plugin-tree/README.md‎
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diff --git a/‎packages/plugin-tree/src/ObjectTree.hostConfigExported-8253.test.ts‎
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@@ -0,0 +1,58 @@
+---
+'@object-ui/types': minor
+'@object-ui/plugin-tree': minor
+'@object-ui/plugin-view': patch
+'@object-ui/app-shell': patch
+---
+
+Derive `TreeViewConfig` from `@objectstack/spec` and drop `titleField`, the key the
+protocol refuses on `ListView.tree` (objectui#8841).
+
+**What was wrong.** `@object-ui/types` published `TreeViewConfig` as a hand-written
+interface — a copy of the protocol's `ListView.tree` block under a second name — and the
+copy declared a fifth key, `titleField`. `@objectstack/spec@17.4.0` refuses that key
+there by name: `TreeConfigSchema` is a `strictObject` since spec #15469 closed the
+`.passthrough()` window 17.3.0 left open. So this package's published face accepted what
+the contract rejects, and an author who followed `@object-ui/types` was refused at
+publish with `Unrecognized key(s) on this tree configuration: 'titleField'`. The copy was
+invisible to `scripts/check-spec-symbol-derivation.mjs`, which matches spec symbols BY
+NAME — a hand copy renamed away from the spec's symbol has nothing for its rule 1 to
+match (objectui#4592's recorded blind spot).
+
+**The grades, and why.**
+
+- `@object-ui/types` — **minor**. `TreeViewConfig` is now
+  `NonNullable<ListView['tree']>` from `@objectstack/spec/ui`, and `titleField` is
+  removed from a **published** exported type. That is breaking for a producer that
+  annotates a `tree` block carrying the key; per this repo's version-alignment policy
+  (AGENTS.md — objectui's major tracks `@objectstack`'s) objectui's own breaking changes
+  ship as `minor` with the breaking semantics stated here. The precedent is the same
+  shape: `Remove the retired striped / bordered / virtualScroll list-view surface`
+  (`@object-ui/types` 17.6.0, minor) propagated a spec-side retirement into this package
+  the same way.
+- `@object-ui/plugin-tree` — **minor**. `getTreeConfig`'s `labelField` chain loses its
+  third rung, `?? schema.titleField`. That rung read the flattened **node**, never the
+  block, and `titleField` is declared on neither face — not on `ObjectTreeSchema` (the TS
+  interface or its zod mirror) and not on the protocol's `ListView.tree`. It is a runtime
+  behaviour change, graded like one. The README's claim that this block is "the single
+  declaration of that shape" is corrected in the same stroke: the protocol owns it, and
+  this package publishes it derived.
+- `@object-ui/plugin-view` — **patch**. `ObjectViewProps.views[n].tree` still resolves to
+  `TreeViewConfig`; what it admits narrows with the type. Type-only, no runtime change.
+- `@object-ui/app-shell` — **patch**. The console's `tree` composition keeps both rungs;
+  only the second one's annotation changes (see below). No runtime change.
+
+**The tolerant reads are kept, and deliberately left undeclared.** Three
+`labelField || titleField` dual-reads survive — `plugin-view`'s and `plugin-list`'s
+`'tree'` branches and the console's own composition in `app-shell` — so a view record
+that already stores `tree.titleField` keeps resolving exactly as before, and
+objectui#6557's pin on that rung stays green. They read through `any` now; the console's
+canonical rung stays annotated `TreeViewConfig` while its legacy rung is not, because
+casting it to a type that no longer carries the key cannot compile and re-declaring the
+key locally would fossilise a renderer-side alias into a second contract — the AGENTS.md
+#0.1 defect this change undoes. Retiring those three reads is a follow-up.
+
+**Migration.** A host that writes `tree.titleField` should write `tree.labelField`, which
+is the protocol's spelling and already wins wherever both are present. Nothing that
+renders today stops rendering; what changes is that the key is now reported at compile
+time by the same face that will refuse it at publish, instead of only at publish.
@@ -2627,18 +2627,30 @@ function ObjectViewInner({ dataSource, objects, onEdit, externalRefreshKey }: an
                     // auto-detects when omitted.
                     //
                     // Read AS `TreeViewConfig` (`@object-ui/types`, objectui#8253):
-                    // `viewDef` is `Record<string, any>`, so both rungs below were
-                    // `any` property accesses and a misspelling was invisible. This
-                    // is the half of objectui#7559 a declaration CAN close, on the
-                    // one block that now has a declaration to close it with — it
-                    // does NOT make a missing rung visible, which is what the census
-                    // pin (`ObjectView.relayRungCensus-7559.test.ts`) is for.
+                    // `viewDef` is `Record<string, any>`, so the canonical rung
+                    // below was an `any` property access and a misspelling was
+                    // invisible. This is the half of objectui#7559 a declaration CAN
+                    // close, on the one block that now has a declaration to close it
+                    // with — it does NOT make a missing rung visible, which is what
+                    // the census pin (`ObjectView.relayRungCensus-7559.test.ts`) is
+                    // for.
                     //
                     // ⚠️ The cast is repeated per rung rather than hoisted into a
                     // local: objectui#6557's convergence pin reads these seam lines
                     // out of this file and requires each to name `viewDef` itself.
+                    //
+                    // ⛔ The `titleField` rung is deliberately NOT cast (objectui#8841).
+                    // `TreeViewConfig` is now the spec's `ListView.tree` block, and
+                    // `@objectstack/spec@17.4.0` refuses `titleField` there by name,
+                    // so casting to it would not compile and re-declaring the key
+                    // locally would fossilise a renderer-side alias into a second
+                    // contract — AGENTS.md #0.1, and the defect objectui#8841 exists
+                    // to undo. The rung stays as an UNDECLARED tolerant fallback,
+                    // read through `any`, kept so already-stored view records keep
+                    // resolving and so objectui#6557's pin on it stays honest. Its
+                    // retirement is a follow-up, ⛔ not a rider here.
                     ...((viewDef.tree as TreeViewConfig | undefined) || {}),
-                    labelField: (viewDef.tree as TreeViewConfig | undefined)?.labelField || (viewDef.tree as TreeViewConfig | undefined)?.titleField || 'name',
+                    labelField: (viewDef.tree as TreeViewConfig | undefined)?.labelField || viewDef.tree?.titleField || 'name',
                 },
                 // The chart block the view DECLARED, forwarded WHOLE — a
                 // pointer, not a copy of its key set (objectui#7823).
 
@@ -77,8 +77,19 @@ user can create. To render a tree from authored metadata, write the
 
 Host config is **not** untyped config. A block a host stores and re-writes is a
 contract, so the per-view `tree` block is exported from `@object-ui/types` and
-is the single declaration of that shape — the renderer imports it rather than
-keeping a private copy (objectui#8253, ruled 2026-09-07):
+the renderer imports it rather than keeping a private copy (objectui#8253,
+ruled 2026-09-07).
+
+⚠️ It is **not the single declaration of that shape**, and saying so was itself
+the defect objectui#8841 fixed. `@objectstack/spec` owns this block — it
+declares it as `TreeConfig` and hangs it on `ListView.tree` — and
+`@object-ui/types` already publishes it a second way, derived, as
+`ListViewSchema['tree']`. `TreeViewConfig` is now a **derivation of the
+protocol's block** rather than a copy of it — in `packages/types/src/views.ts`
+it is a one-line alias of `NonNullable<ListView['tree']>`, taken from
+`@objectstack/spec/ui`. So the accurate claim is the narrower one: this is the
+name a host writes against, and it tracks the protocol by construction rather
+than by anyone remembering to update it.
 
 ```ts
 import type { TreeViewConfig } from '@object-ui/types';
@@ -98,9 +109,18 @@ Annotating the block is what turns a typo into a diagnostic: `parentFeild` used
 to be stored, read by nobody and reported by nothing, because the `views` entry
 admits any key. Against this type it is a compile error.
 
-`titleField` is also declared — a legacy second rung for `labelField`, kept
-because the console's own composition still reads it. Prefer `labelField`,
-which wins wherever both are present.
+⛔ `titleField` is **not** part of this block. objectui#8253 declared it as a
+legacy second rung for `labelField`; `@objectstack/spec@17.4.0` refuses
+`tree.titleField` by name (`TreeConfigSchema` is strict since spec #15469), so
+declaring it published a key the protocol rejects — an author who followed this
+type was refused at publish. objectui#8841 removed it.
+
+The renderers still *tolerate* a `titleField` already stored on a view record:
+`plugin-view`, `plugin-list` and the console's own composition each fall back to
+it when `labelField` is absent, so nothing that renders today stops rendering.
+Those reads are untyped tolerance awaiting a follow-up, ⛔ not a declaration —
+write `labelField`, which is the protocol's spelling and wins wherever both are
+present.
 
 ⛔ This does not make `tree` an authorable view type. objectui#5321 is
 unchanged: the block is written by a **host**, never by a document author, and
 
@@ -26,6 +26,18 @@
  * maintainer 「同意」), option (a): `packages/types` exports the config, the
  * module-local copy becomes an import of it, and ⛔ there is no second copy.
  *
+ * ## What objectui#8841 changed here
+ *
+ * objectui#8253 shipped that export as a hand-written interface — a copy of the
+ * protocol's `ListView.tree` block under a second name — and the copy declared a
+ * fifth key, `titleField`, that `@objectstack/spec@17.4.0` REFUSES there. The
+ * pins in this file did not catch it because the census was a LITERAL KEY LIST
+ * maintained beside the type: the list was written to match the drift, so it
+ * agreed with the defect. objectui#8841 re-derives the type from the protocol
+ * and re-pins the census as PARITY WITH THE PROTOCOL — plus a runtime leg that
+ * reads the installed `TreeConfigSchema` by content, because a compile-time pin
+ * on a derived alias can only restate its own derivation.
+ *
  * ## Why the import below says `@object-ui/types` and not `../../types/src`
  *
  * This is the load-bearing part of the pin, not a style choice. This package's
@@ -57,6 +69,16 @@ import { describe, it, expect } from 'vitest';
 // relative path into `packages/types/src`.
 import type { TreeViewConfig } from '@object-ui/types';
 
+// The PROTOCOL's own declaration of this block, imported for the parity pins
+// below (objectui#8841). `@object-ui/types` derives `TreeViewConfig` from
+// `ListView['tree']`, so this import is the other end of that derivation and
+// the only thing a census can honestly be total over.
+import { TreeConfigSchema } from '@objectstack/spec/ui';
+import type { ListView as SpecListView } from '@objectstack/spec/ui';
+
+/** The protocol's `ListView.tree` block. */
+type SpecTreeConfig = NonNullable<SpecListView['tree']>;
+
 /* -------------------------------------------------------------------------- */
 /* Compile-time pins — compiled by tsconfig.test.json, chained off type-check. */
 /* -------------------------------------------------------------------------- */
@@ -66,49 +88,82 @@ type Equal<A, B> =
   (<T>() => T extends A ? 1 : 2) extends (<T>() => T extends B ? 1 : 2) ? true : false;
 type IsAny<T> = 0 extends 1 & T ? true : false;
 
-/**
- * The keys `getTreeConfig` in `ObjectTree.tsx` reads off this block, and the
- * ones the ruling says the type carries EXACTLY. Pinned as a `keyof` equality
- * rather than a bag of `HasKey` checks, because equality is the only spelling
- * that fails in BOTH directions — a key added here without a reader is as much
- * a defect as a key removed from under one.
- */
-type DeclaredKey =
-  | 'parentField'
-  | 'labelField'
-  | 'titleField'
-  | 'fields'
-  | 'defaultExpandedDepth';
-
-describe('objectui#8253 — TreeViewConfig is reachable through @object-ui/types', () => {
+describe('objectui#8253/#8841 — TreeViewConfig is the protocol\'s block, reachable through @object-ui/types', () => {
   it('is pinned at compile time', () => {
     // Non-vacuity. `keyof any` is `string | number | symbol`, and every
     // `Equal<…>` below would report whatever an `any` made convenient. If the
     // import ever resolves to `any` — a broken export map degrades exactly
     // this way — this line fails FIRST and names the reason.
     type _ConfigIsReal = Assert<Equal<IsAny<TreeViewConfig>, false>>;
+    type _SpecConfigIsReal = Assert<Equal<IsAny<SpecTreeConfig>, false>>;
+
+    // ⭐ THE CENSUS, and objectui#8841 changed what it is made of. It used to be
+    // a LITERAL key list maintained here by hand — and a hand-maintained list
+    // is exactly what let `titleField` through: the list was updated to match
+    // the drift, so the pin agreed with the defect and stayed green while the
+    // published type accepted a key `@objectstack/spec@17.4.0` refuses on
+    // `ListView.tree`. A census can only be total over something it does not
+    // also author.
+    //
+    // So it is PARITY WITH THE PROTOCOL now. Structural equality, not `extends`:
+    // a hand-written twin passes an assignability check in both directions and
+    // would defeat the derivation entirely.
+    type _ParityWithSpec = Assert<Equal<TreeViewConfig, SpecTreeConfig>>;
+
+    // FIRING CONTROL for the line above. An `Equal<…>` loosened until it cannot
+    // report `false` reads exactly like one that still works. This feeds it the
+    // near-miss that actually shipped — the spec's block plus `titleField` — and
+    // requires it to say `false`.
+    type _ParityCanFail = Assert<Equal<Equal<TreeViewConfig, SpecTreeConfig & { titleField?: string }>, false>>;
 
-    // The census, total in both directions. This ALSO refuses an index
-    // signature: `[key: string]: any` would put `string` into `keyof` and this
-    // equality would fail. That matters more than it looks — an index
-    // signature here would re-open the exact hole the card was filed for, by
-    // making every misspelling assignable again.
-    type _Census = Assert<Equal<keyof TreeViewConfig, DeclaredKey>>;
+    // The defect, pinned by name so its return is reported as itself rather
+    // than as an anonymous parity failure.
+    type _TitleFieldIsGone = Assert<Equal<'titleField' extends keyof TreeViewConfig ? true : false, false>>;
+
+    // ⛔ No index signature. This does NOT fall out of parity above: were the
+    // protocol's block `.passthrough()` again (it was, at 17.3.0), both sides
+    // would carry `[key: string]: unknown` and parity would still hold while
+    // every misspelling became assignable again. This line is what pins the
+    // STRICTNESS the card depends on, and it is the line that fires if the
+    // installed `@objectstack/spec` ever drops below 17.4.0.
+    type _NoIndexSignature = Assert<Equal<string extends keyof TreeViewConfig ? true : false, false>>;
 
     // Every key is optional: a host writes the subset it means. `Partial<T>`
     // is structurally identical to `T` only when nothing is required.
     type _AllOptional = Assert<Equal<TreeViewConfig, Partial<TreeViewConfig>>>;
 
-    // Per-key types, read against the sibling node schema's spelling.
-    type _ParentField = Assert<Equal<TreeViewConfig['parentField'], string | undefined>>;
-    type _LabelField = Assert<Equal<TreeViewConfig['labelField'], string | undefined>>;
-    type _TitleField = Assert<Equal<TreeViewConfig['titleField'], string | undefined>>;
-    type _Fields = Assert<Equal<TreeViewConfig['fields'], string[] | undefined>>;
-    type _Depth = Assert<Equal<TreeViewConfig['defaultExpandedDepth'], number | undefined>>;
-
     expect(true).toBe(true);
   });
 
+  it('parity is a measurement, not a tautology: the protocol\'s RUNTIME shape agrees', () => {
+    // The type-level pins above are all compile-time, and a compile-time pin on
+    // a derived alias can only ever restate the derivation. This is the leg that
+    // reads the installed artifact instead: the same `TreeConfigSchema` the
+    // publisher parses against, by content.
+    //
+    // ⛔ Deliberately NOT a literal key-set equality. Freezing the protocol's
+    // key list here would make a benign spec addition red in objectui and would
+    // put a second hand-maintained list back in the file this card emptied. What
+    // is pinned is the DEFECT and the INSTRUMENT, not the census.
+    const keys = Object.keys(TreeConfigSchema.shape);
+    expect(keys).not.toContain('titleField');
+
+    // FIRING CONTROL for the line above, same instrument: a key the protocol
+    // DOES declare is found, so the zero is a reading about `titleField` and
+    // not about an empty shape or an import that resolved to a stub.
+    expect(keys).toContain('parentField');
+
+    // FIRING CONTROL — the schema accepts what it declares, so the refusal
+    // below is a statement about the KEY and not about a schema that refuses
+    // everything.
+    expect(TreeConfigSchema.safeParse({ parentField: 'parent_id' }).success).toBe(true);
+
+    // The refusal the card was filed for, taken from the protocol itself.
+    const refused = TreeConfigSchema.safeParse({ titleField: 'name' });
+    expect(refused.success).toBe(false);
+    expect(JSON.stringify(refused.error?.issues)).toContain('titleField');
+  });
+
   it('refuses the misspelling the card was filed for, at compile time', () => {
     // ⭐ A FRESH object literal is the right instrument HERE, and it is the
     // wrong one in `types/src/__tests__/menu-item-union.test.ts` — worth