fix(mcp): filter project scope before dedup

Applied the project-scope filter before connection-equivalence deduplication so a project server can no longer shadow a differently-named but equivalent user server and then be dropped, leaving none.

Fixes #6786

packages/coding-agent/src/capability/index.ts

@@ -154,6 +154,10 @@ async function loadImpl<T>(
 				continue;
 			}
 
+			if (options.filter && !options.filter(itemWithSource)) {
+				continue;
+			}
+
 			itemWithSource._source.providerName = provider.displayName;
 			allItems.push(itemWithSource as T & { _source: SourceMeta; _shadowed?: boolean });
 			contributedItemCount += 1;

packages/coding-agent/src/capability/types.ts

@@ -72,6 +72,12 @@ export interface LoadOptions {
 	includeDisabled?: boolean;
 	/** Explicit disabled extension IDs to apply instead of settings. */
 	disabledExtensions?: string[];
+	/**
+	 * Drop items before deduplication. Use when a downstream scope filter must
+	 * precede equivalence collapse, so a to-be-filtered item cannot shadow a
+	 * differently-keyed but equivalent survivor. Receives the item's `_source`.
+	 */
+	filter?(item: { _source: SourceMeta }): boolean;
 }
 
 /**