feat: show distinct attribute keys in cmd-k Attributes tab

Add GET /search/attributes/keys endpoint that queries distinct
attribute key names from ClickHouse using JSONExtractKeys. Attribute
keys appear in the cmd-k Attributes tab alongside attribute value
matches from exchange results.

- SearchIndex.distinctAttributeKeys() interface method
- ClickHouseSearchIndex implementation using arrayJoin(JSONExtractKeys)
- SearchController /attributes/keys endpoint
- useAttributeKeys() React Query hook
- buildSearchData includes attribute keys as 'attribute' category items

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/SearchController.java

@@ -172,6 +172,12 @@ public class SearchController {
         return ResponseEntity.ok(searchService.punchcard(from, to, application));
     }
 
+    @GetMapping("/attributes/keys")
+    @Operation(summary = "Distinct attribute key names across all executions")
+    public ResponseEntity<List<String>> attributeKeys() {
+        return ResponseEntity.ok(searchService.distinctAttributeKeys());
+    }
+
     @GetMapping("/errors/top")
     @Operation(summary = "Top N errors with velocity trend")
     public ResponseEntity<List<TopError>> topErrors(

cameleer3-server-app/src/main/java/com/cameleer3/server/app/search/ClickHouseSearchIndex.java

@@ -305,6 +305,21 @@ public class ClickHouseSearchIndex implements SearchIndex {
                    .replace("_", "\\_");
     }
 
+    @Override
+    public List<String> distinctAttributeKeys() {
+        try {
+            return jdbc.queryForList("""
+                    SELECT DISTINCT arrayJoin(JSONExtractKeys(attributes)) AS attr_key
+                    FROM executions FINAL
+                    WHERE tenant_id = 'default' AND attributes != '' AND attributes != '{}'
+                    ORDER BY attr_key
+                    """, String.class);
+        } catch (Exception e) {
+            log.error("Failed to query distinct attribute keys", e);
+            return List.of();
+        }
+    }
+
     private static Map<String, String> parseAttributesJson(String json) {
         if (json == null || json.isBlank()) return null;
         try {

cameleer3-server-core/src/main/java/com/cameleer3/server/core/search/SearchService.java

@@ -25,6 +25,10 @@ public class SearchService {
         return searchIndex.count(request);
     }
 
+    public List<String> distinctAttributeKeys() {
+        return searchIndex.distinctAttributeKeys();
+    }
+
     public ExecutionStats stats(Instant from, Instant to) {
         return statsStore.stats(from, to);
     }

cameleer3-server-core/src/main/java/com/cameleer3/server/core/storage/SearchIndex.java

@@ -5,6 +5,8 @@ import com.cameleer3.server.core.search.SearchRequest;
 import com.cameleer3.server.core.search.SearchResult;
 import com.cameleer3.server.core.storage.model.ExecutionDocument;
 
+import java.util.List;
+
 public interface SearchIndex {
 
     SearchResult<ExecutionSummary> search(SearchRequest request);
@@ -14,4 +16,7 @@ public interface SearchIndex {
     void index(ExecutionDocument document);
 
     void delete(String executionId);
+
+    /** Returns distinct attribute key names across all executions. */
+    List<String> distinctAttributeKeys();
 }

ui/src/api/queries/executions.ts

@@ -32,6 +32,22 @@ export function useExecutionStats(
   });
 }
 
+export function useAttributeKeys() {
+  return useQuery({
+    queryKey: ['search', 'attribute-keys'],
+    queryFn: async () => {
+      const token = (await import('../../auth/auth-store')).useAuthStore.getState().accessToken;
+      const { config } = await import('../../config');
+      const res = await fetch(`${config.apiBaseUrl}/search/attributes/keys`, {
+        headers: { Authorization: `Bearer ${token}` },
+      });
+      if (!res.ok) throw new Error('Failed to load attribute keys');
+      return res.json() as Promise<string[]>;
+    },
+    staleTime: 60_000,
+  });
+}
+
 export function useSearchExecutions(filters: SearchRequest, live = false) {
   const liveQuery = useLiveQuery(5_000);
   return useQuery({

ui/src/components/LayoutShell.tsx

@@ -3,7 +3,7 @@ import { AppShell, Sidebar, TopBar, CommandPalette, CommandPaletteProvider, Glob
 import type { SidebarApp, SearchResult } from '@cameleer/design-system';
 import { useRouteCatalog } from '../api/queries/catalog';
 import { useAgents } from '../api/queries/agents';
-import { useSearchExecutions } from '../api/queries/executions';
+import { useSearchExecutions, useAttributeKeys } from '../api/queries/executions';
 import { useAuthStore } from '../auth/auth-store';
 import { useState, useMemo, useCallback, useEffect, useRef } from 'react';
 import { ContentTabs } from './ContentTabs';
@@ -21,6 +21,7 @@ function healthToColor(health: string): string {
 function buildSearchData(
   catalog: any[] | undefined,
   agents: any[] | undefined,
+  attrKeys: string[] | undefined,
 ): SearchResult[] {
   if (!catalog) return [];
   const results: SearchResult[] = [];
@@ -61,6 +62,17 @@ function buildSearchData(
     }
   }
 
+  if (attrKeys) {
+    for (const key of attrKeys) {
+      results.push({
+        id: `attr-key-${key}`,
+        category: 'attribute',
+        title: key,
+        meta: 'attribute key',
+      });
+    }
+  }
+
   return results;
 }
 
@@ -94,6 +106,7 @@ function LayoutContent() {
   const { timeRange } = useGlobalFilters();
   const { data: catalog } = useRouteCatalog(timeRange.start.toISOString(), timeRange.end.toISOString());
   const { data: agents } = useAgents();
+  const { data: attributeKeys } = useAttributeKeys();
   const { username, logout } = useAuthStore();
   const { open: paletteOpen, setOpen: setPaletteOpen } = useCommandPalette();
   const { scope, setTab } = useScope();
@@ -141,8 +154,8 @@ function LayoutContent() {
   }, [catalog]);
 
   const catalogData = useMemo(
-    () => buildSearchData(catalog, agents as any[]),
+    () => buildSearchData(catalog, agents as any[], attributeKeys),
-    [catalog, agents],
+    [catalog, agents, attributeKeys],
   );
 
   // Stable reference for catalog data — only changes when catalog/agents actually change,