fix(spec): warn loudly on view-key collisions in expandViewContainer

list/form views share one <object>.<key> namespace during container
expansion; a colliding key (e.g. formViews.default vs the implicit
default list) was silently renamed to <key>_2, so action targets and
navigation viewNames referencing the requested name resolved to the
OTHER view — the root cause of the showcase "Log Time" form action
opening the list view and rendering a black/empty form.

- spec: ExpandedViewItem gains optional _diagnostics; uniqueViewName
  renames now stamp a warning naming both views and the blast radius.
- objectql engine + metadata plugin: log expansion warnings at boot.
- app-showcase: rename formViews.default -> edit and point
  showcase_log_time's target at showcase_task.edit (with comments
  documenting the collision).
- tests: 3 new cases covering collision warnings and the clean path.

Closes #2554

Co-Authored-By: Claude <noreply@anthropic.com>

Author: baozhoutao

.changeset/view-expand-collision-warning.md

@@ -0,0 +1,15 @@
+---
+"@objectstack/spec": patch
+"@objectstack/objectql": patch
+"@objectstack/metadata": patch
+---
+
+Surface view-key collisions during view container expansion instead of renaming silently.
+
+`expandViewContainer` keeps its backward-compatible rename behaviour (`<object>.<key>` →
+`<object>.<key>_2` on collision) but now stamps a machine-readable
+`_diagnostics.warnings` entry on the renamed `ExpandedViewItem`, explaining that
+references targeting the requested name (form action targets, navigation `viewName`s)
+will resolve to the *other* view. Both flattening loaders — the ObjectQL engine and the
+MetadataPlugin — log these warnings at boot so the collision is visible instead of
+manifesting as a form action opening a list view (#2554).

examples/app-showcase/src/actions/index.ts

@@ -117,7 +117,9 @@ export const LogTimeAction = defineAction({
   icon: 'clock',
   objectName: task,
   type: 'form',
-  target: 'showcase_task.default',
+  // Targets the `edit` form view — `showcase_task.default` is the LIST view
+  // (the container's main `list` implicitly claims the `default` key).
+  target: 'showcase_task.edit',
   // `record_section` so it surfaces in the Task Detail quick-actions bar too.
   locations: ['record_header', 'record_related', 'record_section'],
   refreshAfter: true,

examples/app-showcase/src/views/task.view.ts

@@ -230,7 +230,12 @@ export const TaskViews = defineView({
 
   formViews: {
     // simple ── single-section form ──────────────────────────────────────
-    default: {
+    // Keyed `edit`, NOT `default`: the container's main `list` implicitly
+    // claims `showcase_task.default`, and list + form views share one
+    // `<object>.<key>` namespace — a `default` form key would be renamed to
+    // `default_2` at expansion (with a boot warning), breaking any action
+    // `target` that references it. See framework issue #2554.
+    edit: {
       type: 'simple',
       data,
       sections: [

packages/metadata/src/plugin.ts

@@ -558,6 +558,9 @@ export class MetadataPlugin implements Plugin {
                     await this.manager.register('view', viewObject, item);
                     totalRegistered++;
                     for (const vi of expandViewContainer(viewObject, item)) {
+                        for (const w of vi._diagnostics?.warnings ?? []) {
+                            ctx.logger.warn(`[MetadataPlugin] View expansion warning for '${vi.name}': ${w.message}`);
+                        }
                         applyProtection(vi as any, {
                             packageId: manifestPackageId,
                             packageVersion: manifestVersion,

packages/metadata/src/view-expand.test.ts

@@ -103,3 +103,51 @@ describe('expandViewContainer — default list with no listViews dup', () => {
     expect(items[0].isDefault).toBe(true);
   });
 });
+
+describe('expandViewContainer — name collisions carry _diagnostics warnings (#2554)', () => {
+  it('warns when formViews.default collides with the implicit default list', () => {
+    const items = expandViewContainer('task', {
+      list: { type: 'grid', label: 'All Tasks', columns: ['title'], data: { provider: 'object', object: 'task' } },
+      formViews: {
+        default: { type: 'simple', data: { provider: 'object', object: 'task' }, sections: [] },
+      },
+    });
+    const list = items.find((i) => i.viewKind === 'list');
+    const form = items.find((i) => i.viewKind === 'form');
+    // Rename behaviour itself is unchanged (backward compat)…
+    expect(list?.name).toBe('task.default');
+    expect(form?.name).toBe('task.default_2');
+    // …but the renamed item now carries a loud, machine-readable warning.
+    expect(list?._diagnostics).toBeUndefined();
+    expect(form?._diagnostics?.valid).toBe(true);
+    expect(form?._diagnostics?.warnings).toHaveLength(1);
+    expect(form?._diagnostics?.warnings[0].path).toBe('name');
+    expect(form?._diagnostics?.warnings[0].message).toContain("'task.default'");
+    expect(form?._diagnostics?.warnings[0].message).toContain("'task.default_2'");
+  });
+
+  it('warns when a formViews key collides with a listViews key', () => {
+    const items = expandViewContainer('task', {
+      listViews: {
+        mine: { type: 'grid', label: 'Mine', columns: ['title'], data: { provider: 'object', object: 'task' } },
+      },
+      formViews: {
+        mine: { type: 'simple', data: { provider: 'object', object: 'task' }, sections: [] },
+      },
+    });
+    const form = items.find((i) => i.viewKind === 'form');
+    expect(form?.name).toBe('task.mine_2');
+    expect(form?._diagnostics?.warnings?.[0].message).toContain("'task.mine'");
+  });
+
+  it('does not stamp _diagnostics on collision-free expansions', () => {
+    const items = expandViewContainer('task', {
+      list: { type: 'grid', label: 'All', columns: ['title'], data: { provider: 'object', object: 'task' } },
+      formViews: {
+        edit: { type: 'simple', data: { provider: 'object', object: 'task' }, sections: [] },
+      },
+    });
+    expect(items).toHaveLength(2);
+    for (const item of items) expect(item._diagnostics).toBeUndefined();
+  });
+});

packages/objectql/src/engine.ts

@@ -1060,6 +1060,9 @@ export class ObjectQL implements IDataEngine {
                       // the per-view `package` layer the switcher + Studio consume.
                       if (key === 'views' && isAggregatedViewContainer(toRegister)) {
                           for (const vi of expandViewContainer(itemName, toRegister)) {
+                              for (const w of vi._diagnostics?.warnings ?? []) {
+                                  this.logger.warn(`View expansion warning for '${vi.name}': ${w.message}`, { from: id });
+                              }
                               this._registry.registerItem('view', vi, 'name' as any, id);
                           }
                       }

packages/spec/src/ui/view.zod.ts

@@ -1131,6 +1131,11 @@ export interface ExpandedViewItem {
   isDefault?: boolean;
   order: number;
   scope: 'package';
+  /** Non-blocking expansion diagnostics (MetadataValidationResult wire shape).
+   *  Present only when the item's name had to be rewritten to avoid a
+   *  collision — loaders surface `warnings` in their boot/HMR logs and
+   *  Studio can badge the view. */
+  _diagnostics?: { valid: boolean; warnings: Array<{ path: string; message: string }> };
 }
 
 /** True when a raw view artifact still uses the aggregated container shape
@@ -1162,6 +1167,29 @@ function uniqueViewName(base: string, used: Set<string>): string {
   return name;
 }
 
+/** Stamp a rename warning on an expanded item whose `<object>.<key>` name was
+ *  already taken (e.g. `formViews.default` vs the implicit default `list`).
+ *  The rename itself is kept for backward compatibility — this makes it LOUD:
+ *  loaders log the warning and Studio can render it, so authors discover that
+ *  references to the requested name (form action `target`s, navigation
+ *  `viewName`s) resolve to a DIFFERENT view. */
+function stampRenameWarning(item: ExpandedViewItem, requestedName: string): void {
+  if (item.name === requestedName) return;
+  item._diagnostics = {
+    valid: true,
+    warnings: [{
+      path: 'name',
+      message:
+        `View key collision: '${requestedName}' is already registered by another view in this `
+        + `defineView container (list and form views share one '<object>.<key>' namespace, and the `
+        + `default 'list' implicitly claims '<object>.default'). This ${item.viewKind} view was `
+        + `renamed to '${item.name}'. References targeting '${requestedName}' — form action `
+        + `targets, navigation viewNames — will resolve to the OTHER view. Rename the view key `
+        + `to something unique to remove this warning.`,
+    }],
+  };
+}
+
 function cloneViewConfig(v: any): any {
   try {
     return structuredClone(v);
@@ -1191,9 +1219,12 @@ export function expandViewContainer(object: string, container: any): ExpandedVie
     container.listViews && typeof container.listViews === 'object' ? container.listViews : {};
   for (const [k, v] of Object.entries<any>(listViews)) {
     if (!v || typeof v !== 'object') continue;
-    const name = uniqueViewName(`${object}.${k}`, used);
+    const requested = `${object}.${k}`;
+    const name = uniqueViewName(requested, used);
     listSigToName.set(viewSignature(v), name);
-    out.push({ name, object, viewKind: 'list', label: v.label, config: cloneViewConfig(v), order: order++, scope: 'package' });
+    const item: ExpandedViewItem = { name, object, viewKind: 'list', label: v.label, config: cloneViewConfig(v), order: order++, scope: 'package' };
+    stampRenameWarning(item, requested);
+    out.push(item);
   }
   const defaultList = container.list;
   let defaultListName: string | undefined;
@@ -1203,8 +1234,11 @@ export function expandViewContainer(object: string, container: any): ExpandedVie
       defaultListName = dup; // already represented by a named listViews entry
     } else {
       const key = typeof defaultList.name === 'string' && defaultList.name ? defaultList.name : 'default';
-      const name = uniqueViewName(`${object}.${key}`, used);
-      out.push({ name, object, viewKind: 'list', label: defaultList.label, config: cloneViewConfig(defaultList), order: order++, scope: 'package' });
+      const requested = `${object}.${key}`;
+      const name = uniqueViewName(requested, used);
+      const item: ExpandedViewItem = { name, object, viewKind: 'list', label: defaultList.label, config: cloneViewConfig(defaultList), order: order++, scope: 'package' };
+      stampRenameWarning(item, requested);
+      out.push(item);
       defaultListName = name;
     }
   }
@@ -1220,16 +1254,22 @@ export function expandViewContainer(object: string, container: any): ExpandedVie
     container.formViews && typeof container.formViews === 'object' ? container.formViews : {};
   for (const [k, v] of Object.entries<any>(formViews)) {
     if (!v || typeof v !== 'object') continue;
-    const name = uniqueViewName(`${object}.${k}`, used);
+    const requested = `${object}.${k}`;
+    const name = uniqueViewName(requested, used);
     formSigSeen.add(viewSignature(v));
-    out.push({ name, object, viewKind: 'form', label: v.label, config: cloneViewConfig(v), order: order++, scope: 'package' });
+    const item: ExpandedViewItem = { name, object, viewKind: 'form', label: v.label, config: cloneViewConfig(v), order: order++, scope: 'package' };
+    stampRenameWarning(item, requested);
+    out.push(item);
   }
   const defaultForm = container.form;
   let defaultFormName: string | undefined;
   if (defaultForm && typeof defaultForm === 'object' && !formSigSeen.has(viewSignature(defaultForm))) {
     const key = typeof defaultForm.name === 'string' && defaultForm.name ? defaultForm.name : 'form';
-    const name = uniqueViewName(`${object}.${key}`, used);
-    out.push({ name, object, viewKind: 'form', label: defaultForm.label, config: cloneViewConfig(defaultForm), order: order++, scope: 'package' });
+    const requested = `${object}.${key}`;
+    const name = uniqueViewName(requested, used);
+    const item: ExpandedViewItem = { name, object, viewKind: 'form', label: defaultForm.label, config: cloneViewConfig(defaultForm), order: order++, scope: 'package' };
+    stampRenameWarning(item, requested);
+    out.push(item);
     defaultFormName = name;
   }
   if (!defaultFormName && out.length > formStart) defaultFormName = out[formStart].name;