diff --git a/apps/desktop/src/components/diagram/DiagramToolbar.vue b/apps/desktop/src/components/diagram/DiagramToolbar.vue
index 961b8ee97d..286abced93 100644
--- a/apps/desktop/src/components/diagram/DiagramToolbar.vue
+++ b/apps/desktop/src/components/diagram/DiagramToolbar.vue
@@ -179,7 +179,7 @@ function connectionIconType(id: string) {
       {{ t("diagram.copyJoinSql") }}
     </Button>
 
-    <Button v-if="focusTableName && tablesCount > 0" variant="outline" size="sm" class="h-8 px-2 text-xs" @click="emit('toggle-show-all-tables')">
+    <Button v-if="focusTableName && tablesCount > 0" :disabled="loadingDiagram" variant="outline" size="sm" class="h-8 px-2 text-xs" @click="emit('toggle-show-all-tables')">
       {{ showAllTables ? t("diagram.relatedTables") : t("diagram.allTables") }}
     </Button>
 
diff --git a/apps/desktop/src/components/diagram/SchemaDiagramDialog.vue b/apps/desktop/src/components/diagram/SchemaDiagramDialog.vue
index 29ae9a3eb4..b49f8c9df4 100644
--- a/apps/desktop/src/components/diagram/SchemaDiagramDialog.vue
+++ b/apps/desktop/src/components/diagram/SchemaDiagramDialog.vue
@@ -1,3 +1,8 @@
+<script lang="ts">
+// Reopening a cached closure also reuses its namespace choices, avoiding discovery requests.
+const diagramNamespaceSnapshots = new Map<string, { databases: string[]; schemas: string[]; defaultSchema: string }>();
+</script>
+
 <script setup lang="ts">
 import { computed, markRaw, nextTick, onMounted, onUnmounted, provide, ref, watch } from "vue";
 import { useI18n } from "vue-i18n";
@@ -15,6 +20,9 @@ import "@vue-flow/minimap/dist/style.css";
 import { useConnectionStore } from "@/stores/connectionStore";
 import { useGraphStore } from "@/lib/diagram/graph-store";
 import * as api from "@/lib/backend/api";
+import { loadFocusedDiagram, diagramIdentityKey, diagramIndexes, type FocusedDiagramLoadRequest } from "@/lib/diagram/diagramMetadataLoader";
+import { focusedDiagramCacheKey, getFocusedDiagramCache, loadFocusedDiagramCached } from "@/lib/diagram/diagramMetadataCache";
+import { saveFocusedDiagramState } from "@/lib/diagram/draft-storage";
 import { DIAGRAM_SQL_TYPES, isSchemaAware as isSchemaAwareDatabase } from "@/lib/database/databaseCapabilities";
 import { databaseOptionsForConnection, fetchNamespaceOptionsForConnection } from "@/composables/useDatabaseOptions";
 import { buildDiagramJoinSql, buildDiagramRelationships, diagramTableId, filterDiagramTables, mergeRelationshipsWithInferred, normalizeCustomDiagramRelationship, type CustomDiagramRelationship, type DiagramPosition, type DiagramTable, isDraftTable, needsDiagramSync } from "@/lib/diagram/erDiagram";
@@ -138,9 +146,9 @@ function deepCloneJson<T>(obj: T): T {
 
 function captureHistorySnapshot(): HistorySnapshot {
   const diagramNodes = visibleTables.value.map((table) => ({
-    id: table.name,
+    id: getTableKey(table),
     type: "table",
-    position: positions.value[table.name] || { x: 0, y: 0 },
+    position: positions.value[getTableKey(table)] || { x: 0, y: 0 },
     data: { table },
   }));
   return {
@@ -163,9 +171,9 @@ function recordHistory() {
 
 function syncGraphStoreFromPositions() {
   const diagramNodes = visibleTables.value.map((table) => ({
-    id: table.name,
+    id: getTableKey(table),
     type: "table",
-    position: positions.value[table.name] || { x: 0, y: 0 },
+    position: positions.value[getTableKey(table)] || { x: 0, y: 0 },
     data: { table },
   }));
   graphStore.setNodes(diagramNodes);
@@ -209,10 +217,14 @@ function handleRedo() {
   if (restored) applyHistorySnapshot(restored);
 }
 
+function canLayoutLayer(layer: { tableNames: string[] }): boolean {
+  return loadedDiagramScope.value !== "focused" || layer.tableNames.every((name) => tables.value.some((table) => getTableKey(table) === name || (table.name === name && table.schema === selectedSchemas.value[0])));
+}
+
 function fitAllFreeLayers() {
   const heights = tableHeightsMap();
   for (const layer of layerStore.layers) {
-    if ((layer.layoutMode ?? "auto") === "free") {
+    if (canLayoutLayer(layer) && (layer.layoutMode ?? "auto") === "free") {
       sizeLayerToFit(layer, positions.value, heights);
     }
   }
@@ -222,7 +234,7 @@ function fitAllFreeLayers() {
 function fitAllLayers() {
   const heights = tableHeightsMap();
   for (const layer of layerStore.layers) {
-    sizeLayerToFit(layer, positions.value, heights);
+    if (canLayoutLayer(layer)) sizeLayerToFit(layer, positions.value, heights);
   }
 }
 
@@ -275,6 +287,7 @@ const props = defineProps<{
   prefillConnectionId?: string;
   prefillDatabase?: string;
   prefillSchema?: string;
+  prefillCatalog?: string;
   focusTableName?: string;
   focusTableNames?: string[];
 }>();
@@ -314,6 +327,16 @@ const totalTableCount = ref(0);
 const failedTableCount = ref(0);
 const positions = ref<Record<string, DiagramPosition>>({});
 const showAllTables = ref(false);
+type DiagramLoadMode = "focused" | "full";
+const loadedDiagramScope = ref<DiagramLoadMode>("full");
+let persistedTableSnapshot: DiagramTable[] = [];
+let diagramLoadGeneration = 0;
+let initializationGeneration = 0;
+let namespaceGeneration = 0;
+const focusedRoots = computed(() => {
+  const names = props.focusTableNames?.length ? props.focusTableNames : props.focusTableName ? [props.focusTableName] : [];
+  return names.filter((name) => name.trim()).map((name) => ({ name, schema: selectedSchemas.value[0] || schema.value || database.value }));
+});
 const diagramMode = ref<"table" | "engineering">("table");
 
 const FIT_VIEW_OPTIONS = { padding: 0.15, duration: 150, minZoom: 0.05, maxZoom: 2 } as const;
@@ -404,12 +427,22 @@ const isSchemaAware = computed(() => isSchemaAwareDatabase(selectedConnection.va
 
 const isAllSchemasSelected = computed(() => isSchemaAware.value && schemas.value.length > 0 && schemas.value.every((s) => selectedSchemas.value.includes(s)));
 
-const isMultiSchema = computed(() => isSchemaAware.value && (selectedSchemas.value.length > 1 || isAllSchemasSelected.value));
+const isMultiSchema = computed(() => new Set(tables.value.map((table) => table.schema ?? "")).size > 1 || (isSchemaAware.value && (selectedSchemas.value.length > 1 || isAllSchemasSelected.value)));
+
+const tableNameCounts = computed(() => {
+  const counts = new Map<string, number>();
+  for (const table of tables.value) counts.set(table.name, (counts.get(table.name) ?? 0) + 1);
+  return counts;
+});
 
 function getTableKey(table: { name: string; schema?: string }): string {
   return diagramTableId(table, isMultiSchema.value);
 }
 
+function canUseUnqualifiedTableName(table: DiagramTable): boolean {
+  return tableNameCounts.value.get(table.name) === 1 && (loadedDiagramScope.value !== "focused" || !table.schema || table.schema === selectedSchemas.value[0]);
+}
+
 const effectiveSchemaKey = computed(() => {
   // Non-schema-aware drivers historically persisted with the database name
   // in this slot (loadSchemas assigned schema = database); keep legacy keys.
@@ -431,33 +464,11 @@ const tableMap = computed(() => {
   return map;
 });
 
-const allRelationships = computed(() => buildDiagramRelationships(tables.value, customRelationships.value, isMultiSchema.value));
-
-const relatedTableNames = computed(() => {
-  const selected = props.focusTableNames?.filter((name) => name.trim());
-  if (selected && selected.length > 1) return new Set(selected);
-  const focus = props.focusTableName;
-  const names = new Set<string>();
-  if (!focus) return names;
-  names.add(focus);
-  for (const relationship of allRelationships.value) {
-    if (relationship.sourceTable === focus) names.add(relationship.targetTable);
-    if (relationship.targetTable === focus) names.add(relationship.sourceTable);
-  }
-  return names;
-});
-
 const visibleTables = computed(() => {
   const filtered = filterDiagramTables(
     tables.value.filter((table) => !table.pendingDrop),
     tableSearch.value,
   );
-  if ((props.focusTableNames?.length ?? 0) > 1 && !showAllTables.value && !tableSearch.value.trim()) {
-    return filtered.filter((table) => relatedTableNames.value.has(table.name) || relatedTableNames.value.has(getTableKey(table)));
-  }
-  if (props.focusTableName && !showAllTables.value && !tableSearch.value.trim()) {
-    return filtered.filter((table) => relatedTableNames.value.has(table.name) || relatedTableNames.value.has(getTableKey(table)));
-  }
   return filtered;
 });
 
@@ -619,7 +630,9 @@ function handleLayerChanged() {
 }
 
 async function applyAutoLayout(options?: { skipHistory?: boolean }) {
+  const generation = diagramLoadGeneration;
   await nextTick();
+  if (!open.value || generation !== diagramLoadGeneration) return;
   const layoutTables = canvasVisibleTables.value;
   if (layoutTables.length === 0) return;
 
@@ -642,8 +655,9 @@ async function applyAutoLayout(options?: { skipHistory?: boolean }) {
   }));
 
   // Only pass visible layers into ELK so hidden layers are not reflowed
-  const layoutLayers = layerStore.layers.filter((l) => l.visible);
+  const layoutLayers = layerStore.layers.filter((l) => l.visible && canLayoutLayer(l));
   const result = await computeLayoutWithLayers(diagramNodes, diagramEdges, layoutLayers);
+  if (!open.value || generation !== diagramLoadGeneration) return;
 
   // Freeze positions for tables in hidden layers
   const nextPositions: Record<string, DiagramPosition> = { ...positions.value };
@@ -744,6 +758,11 @@ const canSyncStructure = computed(() => supportsTableStructureEditing(selectedCo
 function persistDraftAndLayers() {
   if (!connectionId.value || !database.value) return;
   const schemaKey = effectiveSchemaKey.value;
+  if (loadedDiagramScope.value === "focused") {
+    saveFocusedDiagramState(tables.value, persistedTableSnapshot, positions.value, layerStore.toJSON(), connectionId.value, database.value, schemaKey, selectedSchemas.value[0]);
+    persistedTableSnapshot = deepCloneJson(tables.value);
+    return;
+  }
   saveDraftTables(tables.value, connectionId.value, database.value, schemaKey);
   saveLiveTablePatches(tables.value, connectionId.value, database.value, schemaKey);
   savePersistedLayers(layerStore.toJSON(), connectionId.value, database.value, schemaKey);
@@ -976,7 +995,7 @@ function handleInspectorRemoveRelationship(id: string) {
 
 async function handleSyncedDraftTables(_names: string[]) {
   toast(t("diagram.syncToDatabase"), 2000);
-  await loadDiagram();
+  await loadDiagram({ force: true });
 }
 
 function syncVueFlowNodes() {
@@ -1290,25 +1309,26 @@ async function copyJoinSql() {
 
 async function loadDatabases(id: string) {
   if (!id) return;
+  const generation = namespaceGeneration;
+  const active = () => open.value && generation === namespaceGeneration && id === connectionId.value;
   loadingDatabases.value = true;
   databases.value = [];
   try {
     await store.ensureConnected(id);
+    if (!active()) return;
     const config = store.getConfig(id);
-    if (config?.db_type === "dameng") {
-      // 达梦的"数据库"概念对应 schema，使用 fetchNamespaceOptionsForConnection
-      databases.value = await fetchNamespaceOptionsForConnection(id, config);
-    } else {
-      const dbs = await api.listDatabases(id);
-      databases.value = databaseOptionsForConnection(
-        dbs.map((db) => db.name),
-        config,
-      );
-    }
-  } catch (e: any) {
-    toast(e?.message || String(e), 5000);
+    const names =
+      config?.db_type === "dameng"
+        ? await fetchNamespaceOptionsForConnection(id, config)
+        : databaseOptionsForConnection(
+            (await api.listDatabases(id)).map((db) => db.name),
+            config,
+          );
+    if (active()) databases.value = names;
+  } catch (error: any) {
+    if (active()) toast(error?.message || String(error), 5000);
   } finally {
-    loadingDatabases.value = false;
+    if (active()) loadingDatabases.value = false;
   }
 }
 
@@ -1322,60 +1342,72 @@ async function loadSchemas() {
     selectedSchemas.value = [database.value];
     return;
   }
-
+  const id = connectionId.value;
+  const db = database.value;
+  const catalog = props.prefillCatalog;
+  const generation = namespaceGeneration;
+  const active = () => open.value && generation === namespaceGeneration && id === connectionId.value && db === database.value && catalog === props.prefillCatalog;
   loadingSchemas.value = true;
   try {
-    const names = await api.listSchemas(connectionId.value, database.value);
+    const names = await api.listSchemas(id, db);
+    if (!active()) return;
     schemas.value = names;
-    if (props.prefillSchema && names.includes(props.prefillSchema)) {
-      schema.value = props.prefillSchema;
-      selectedSchemas.value = [props.prefillSchema];
-    } else {
-      const defaultSchema = names.includes("public") ? "public" : (names[0] ?? "");
-      schema.value = defaultSchema;
-      selectedSchemas.value = defaultSchema ? [defaultSchema] : [];
-    }
-  } catch (e: any) {
-    toast(e?.message || String(e), 5000);
+    const defaultSchema = props.prefillSchema && names.includes(props.prefillSchema) ? props.prefillSchema : names.includes("public") ? "public" : (names[0] ?? "");
+    schema.value = defaultSchema;
+    selectedSchemas.value = defaultSchema ? [defaultSchema] : [];
+  } catch (error: any) {
+    if (active()) toast(error?.message || String(error), 5000);
   } finally {
-    loadingSchemas.value = false;
+    if (active()) loadingSchemas.value = false;
   }
 }
 
 async function setConnection(id: string) {
+  namespaceGeneration++;
   connectionId.value = id;
   database.value = "";
   schema.value = "";
   selectedSchemas.value = [];
   tables.value = [];
+  persistedTableSnapshot = [];
   customRelationships.value = [];
   positions.value = {};
   matchConfirms.value = [];
   matchIgnores.value = [];
   matchResult.value = { relationships: [], conflicts: [], pending: [], stats: { total: 0, high: 0, medium: 0 } };
+  const generation = namespaceGeneration;
   await loadDatabases(id);
+  if (!open.value || generation !== namespaceGeneration || id !== connectionId.value) return;
   if (databases.value.length === 1) {
     await setDatabase(databases.value[0]);
   }
 }
 
 async function setDatabase(value: string) {
+  namespaceGeneration++;
   database.value = value;
   tables.value = [];
+  persistedTableSnapshot = [];
   selectedSchemas.value = [];
   customRelationships.value = [];
   positions.value = {};
   matchConfirms.value = [];
   matchIgnores.value = [];
   matchResult.value = { relationships: [], conflicts: [], pending: [], stats: { total: 0, high: 0, medium: 0 } };
+  const id = connectionId.value;
+  const generation = namespaceGeneration;
   await loadSchemas();
+  if (!open.value || generation !== namespaceGeneration || id !== connectionId.value || value !== database.value) return;
+  diagramNamespaceSnapshots.set(JSON.stringify([id, value, props.prefillCatalog]), { databases: [...databases.value], schemas: [...schemas.value], defaultSchema: schema.value });
   if (diagramReady.value) await loadDiagram();
 }
 
 async function setSchema(value: string) {
+  namespaceGeneration++;
   schema.value = value;
   selectedSchemas.value = value ? [value] : [];
   tables.value = [];
+  persistedTableSnapshot = [];
   customRelationships.value = [];
   positions.value = {};
   matchConfirms.value = [];
@@ -1385,9 +1417,11 @@ async function setSchema(value: string) {
 }
 
 async function setSelectedSchemas(values: string[]) {
+  namespaceGeneration++;
   selectedSchemas.value = [...values];
   schema.value = values.length === 1 ? values[0] : "";
   tables.value = [];
+  persistedTableSnapshot = [];
   customRelationships.value = [];
   positions.value = {};
   matchConfirms.value = [];
@@ -1396,135 +1430,156 @@ async function setSelectedSchemas(values: string[]) {
   if (diagramReady.value) await loadDiagram();
 }
 
-async function loadTableDiagramData(tableName: string, querySchema: string, tableComment?: string | null): Promise<DiagramTable> {
-  try {
-    const [columns, foreignKeys, indexes] = await Promise.all([
-      api.getColumns(connectionId.value, database.value, querySchema, tableName),
-      api.listForeignKeys(connectionId.value, database.value, querySchema, tableName).catch(() => []),
-      api.listIndexes(connectionId.value, database.value, querySchema, tableName).catch(() => []),
-    ]);
-    return {
-      name: tableName,
-      schema: querySchema,
-      comment: tableComment ?? null,
-      columns,
-      foreignKeys,
-      indexes: indexes.map((index) => ({
-        id: index.name,
-        name: index.name,
-        columns: [...index.columns],
-        isUnique: index.is_unique,
-        isPrimary: index.is_primary,
-        filter: index.filter ?? "",
-        indexType: index.index_type ?? "",
-        includedColumns: index.included_columns ?? [],
-        comment: index.comment ?? "",
-        markedForDrop: false,
-        original: index,
-      })),
-    };
-  } catch (e) {
-    failedTableCount.value += 1;
-    console.warn(`[diagram] failed to load table metadata: ${querySchema}.${tableName}`, e);
-    return { name: tableName, schema: querySchema, comment: tableComment ?? null, columns: [], foreignKeys: [], indexes: [] };
-  }
-}
-
-async function loadDiagram() {
-  if (!diagramReady.value) return;
-
-  loadingDiagram.value = true;
-  tables.value = [];
-  positions.value = {};
-  loadedTableCount.value = 0;
-  totalTableCount.value = 0;
-  failedTableCount.value = 0;
-  try {
-    await store.ensureConnected(connectionId.value);
-    const targetSchemas = isSchemaAware.value ? selectedSchemas.value : [database.value];
-
-    const schemaTableLists = await Promise.all(
-      targetSchemas.map(async (sc) => {
+async function loadFullDiagram(request: FocusedDiagramLoadRequest, targetSchemas: string[], active: () => boolean): Promise<DiagramTable[]> {
+  const { connectionId: id, database: db, catalog } = request;
+  const lists = await Promise.all(
+    targetSchemas.map(async (sc) => {
+      try {
+        const list = await api.listTables(id, db, sc, undefined, undefined, undefined, undefined, catalog);
+        return list.filter((table) => table.table_type !== "VIEW" && table.table_type !== "MATERIALIZED_VIEW").map((table) => ({ name: table.name, schema: sc, comment: table.comment ?? null }));
+      } catch (error) {
+        console.warn(`[diagram] failed to list tables for schema ${sc}`, error);
+        return [];
+      }
+    }),
+  );
+  const baseTables = lists.flat().sort((a, b) => a.schema.localeCompare(b.schema) || a.name.localeCompare(b.name));
+  if (active()) totalTableCount.value = baseTables.length;
+  const result: DiagramTable[] = [];
+  for (let index = 0; index < baseTables.length; index += METADATA_BATCH_SIZE) {
+    if (!active()) return result;
+    const batch = await Promise.all(
+      baseTables.slice(index, index + METADATA_BATCH_SIZE).map(async (table) => {
         try {
-          const list = await api.listTables(connectionId.value, database.value, sc);
-          // Keep the table comment so the card can render the table description.
-          return list.filter((table) => table.table_type !== "VIEW" && table.table_type !== "MATERIALIZED_VIEW").map((table) => ({ name: table.name, schema: sc, comment: table.comment ?? null }));
-        } catch (e) {
-          console.warn(`[diagram] failed to list tables for schema ${sc}`, e);
-          return [];
+          const [columns, foreignKeys, indexes] = await Promise.all([api.getColumns(id, db, table.schema, table.name, catalog), api.listForeignKeys(id, db, table.schema, table.name, catalog).catch(() => []), api.listIndexes(id, db, table.schema, table.name, catalog).catch(() => [])]);
+          return { ...table, columns, foreignKeys, indexes: diagramIndexes(indexes) };
+        } catch (error) {
+          if (active()) failedTableCount.value += 1;
+          console.warn(`[diagram] failed to load table metadata: ${table.schema}.${table.name}`, error);
+          return { ...table, columns: [], foreignKeys: [], indexes: [] };
         }
       }),
     );
-    const baseTables = schemaTableLists.flat().sort((a, b) => {
-      if (a.schema !== b.schema) return a.schema.localeCompare(b.schema);
-      return a.name.localeCompare(b.name);
-    });
-    totalTableCount.value = baseTables.length;
+    result.push(...batch);
+    if (active()) loadedTableCount.value = result.length;
+  }
+  return result;
+}
 
-    const loadedTables: DiagramTable[] = [];
-    for (let index = 0; index < baseTables.length; index += METADATA_BATCH_SIZE) {
-      const batch = baseTables.slice(index, index + METADATA_BATCH_SIZE);
-      const batchTables = await Promise.all(batch.map((item) => loadTableDiagramData(item.name, item.schema, item.comment)));
-      loadedTables.push(...batchTables);
-      loadedTableCount.value = loadedTables.length;
-    }
+function diagramContextKey(): string {
+  return JSON.stringify([connectionId.value, database.value, props.prefillCatalog, schema.value, selectedSchemas.value, focusedRoots.value]);
+}
 
-    tables.value = loadedTables;
-    const schemaKey = effectiveSchemaKey.value;
-    const drafts = loadDraftTables(connectionId.value, database.value, schemaKey);
-    const liveKeys = new Set(loadedTables.map((t) => getTableKey(t)));
-    const pendingDrafts = drafts.filter((d) => !liveKeys.has(getTableKey(d)) && !liveKeys.has(d.name));
-    if (pendingDrafts.length) {
-      tables.value = [...loadedTables, ...pendingDrafts];
-    }
-    const livePatches = loadLiveTablePatches(connectionId.value, database.value, schemaKey);
-    tables.value = applyLiveTablePatches(tables.value, livePatches);
-    saveDraftTables(tables.value.filter(isDraftTable), connectionId.value, database.value, schemaKey);
-    saveLiveTablePatches(tables.value, connectionId.value, database.value, schemaKey);
-    const savedLayers = loadPersistedLayers(connectionId.value, database.value, schemaKey);
-    if (savedLayers.length) {
-      layerStore.loadLayers(savedLayers);
-      if (isMultiSchema.value) {
-        const rawNameCounts = new Map<string, number>();
-        for (const table of tables.value) {
-          rawNameCounts.set(table.name, (rawNameCounts.get(table.name) ?? 0) + 1);
-        }
-        for (const layer of layerStore.layers) {
-          layer.tableNames = layer.tableNames.map((name) => {
-            if (!name.includes(".")) {
-              const matchedTable = tables.value.find((t) => t.name === name);
-              if (matchedTable && rawNameCounts.get(name) === 1 && matchedTable.schema) {
-                return `${matchedTable.schema}.${matchedTable.name}`;
-              }
-            }
-            return name;
-          });
-        }
+async function loadDiagram(options: { mode?: DiagramLoadMode; force?: boolean } = {}): Promise<void> {
+  if (!diagramReady.value) return;
+  const generation = ++diagramLoadGeneration;
+  const context = diagramContextKey();
+  const active = () => open.value && generation === diagramLoadGeneration && context === diagramContextKey();
+  const mode = options.mode ?? (focusedRoots.value.length && !showAllTables.value ? "focused" : "full");
+  if (tables.value.length === 0) loadedDiagramScope.value = mode;
+  const request: FocusedDiagramLoadRequest = {
+    connectionId: connectionId.value,
+    database: database.value,
+    catalog: props.prefillCatalog,
+    roots: focusedRoots.value,
+    concurrency: METADATA_BATCH_SIZE,
+    onProgress: (loaded, discovered) => {
+      if (!active()) return;
+      loadedTableCount.value = loaded;
+      totalTableCount.value = discovered;
+    },
+  };
+  const key = focusedDiagramCacheKey(request);
+  const cached = mode === "focused" && !options.force ? getFocusedDiagramCache(key) : undefined;
+  // Check memory before connecting or showing the remote loading state.
+  loadingDiagram.value = !cached;
+  loadedTableCount.value = cached?.length ?? 0;
+  totalTableCount.value = cached?.length ?? 0;
+  failedTableCount.value = 0;
+  try {
+    let liveTables = cached;
+    if (!liveTables) {
+      const { connectionId: id, database: db, catalog } = request;
+      if (mode === "focused") {
+        liveTables = await loadFocusedDiagramCached(
+          key,
+          async () => {
+            await store.ensureConnected(id);
+            const result = await loadFocusedDiagram(request, {
+              getColumns: (table) => api.getColumns(id, db, table.schema, table.name, catalog),
+              listForeignKeys: (table) => api.listForeignKeys(id, db, table.schema, table.name, catalog),
+              listIndexes: (table) => api.listIndexes(id, db, table.schema, table.name, catalog),
+              getTableComment: (table) => api.getTableComment(id, db, table.schema, table.name, catalog),
+            });
+            return result.tables;
+          },
+          { force: options.force },
+        );
+      } else {
+        const targetSchemas = isSchemaAware.value ? [...selectedSchemas.value] : [db];
+        await store.ensureConnected(id);
+        if (!active()) return;
+        liveTables = await loadFullDiagram(request, targetSchemas, active);
       }
     }
-    loadCustomRelationships();
-    loadMatchData();
-    updateRelationshipDraftDefaults();
-    showAllTables.value = false;
-    if (failedTableCount.value > 0) {
-      toast(t("diagram.partialError", { count: failedTableCount.value }), 5000);
-    }
-  } catch (e: any) {
-    toast(e?.message || String(e), 5000);
+    if (!active()) return;
+    loadedTableCount.value = totalTableCount.value = liveTables.length;
+    await applyLoadedDiagramTables(liveTables, mode, active);
+    if (active() && failedTableCount.value > 0) toast(t("diagram.partialError", { count: failedTableCount.value }), 5000);
+  } catch (error: any) {
+    if (active()) toast(error?.message || String(error), 5000);
   } finally {
-    loadingDiagram.value = false;
-  }
-  if (tables.value.length > 0) {
-    await nextTick();
-    await restoreOrInitializeLayout();
-    graphStore.clearHistory();
-  } else {
-    syncVueFlowNodes();
+    if (active()) loadingDiagram.value = false;
   }
 }
 
+async function applyLoadedDiagramTables(liveTables: DiagramTable[], mode: DiagramLoadMode, active: () => boolean) {
+  const schemaKey = effectiveSchemaKey.value;
+  const drafts = loadDraftTables(connectionId.value, database.value, schemaKey);
+  const identity = (table: DiagramTable) => diagramIdentityKey({ ...table, schema: table.schema ?? selectedSchemas.value[0] ?? schema.value });
+  const liveKeys = new Set(liveTables.map(identity));
+  const pendingDrafts = drafts.filter((draft) => !liveKeys.has(identity(draft)));
+  const patches = loadLiveTablePatches(connectionId.value, database.value, schemaKey);
+  const nextTables = applyLiveTablePatches([...liveTables, ...pendingDrafts], patches, selectedSchemas.value.length === 1 ? selectedSchemas.value[0] : undefined);
+  tables.value = nextTables;
+  loadedDiagramScope.value = mode;
+  showAllTables.value = mode === "full" && focusedRoots.value.length > 0;
+  positions.value = {};
+  // Metadata reconciliation must not be mistaken for an edit to a saved live patch.
+  persistedTableSnapshot = deepCloneJson(nextTables);
+  if (mode === "full") {
+    saveDraftTables(nextTables, connectionId.value, database.value, schemaKey);
+    saveLiveTablePatches(nextTables, connectionId.value, database.value, schemaKey);
+  } else if (pendingDrafts.length !== drafts.length) {
+    // Only remove drafts whose exact identities were confirmed live by this load.
+    saveDraftTables(pendingDrafts, connectionId.value, database.value, schemaKey);
+  }
+  layerStore.loadLayers(loadPersistedLayers(connectionId.value, database.value, schemaKey));
+  if (isMultiSchema.value) {
+    for (const layer of layerStore.layers) {
+      layer.tableNames = layer.tableNames.map((name) => {
+        const matches = tables.value.filter((table) => table.name === name && (mode !== "focused" || !table.schema || table.schema === selectedSchemas.value[0]));
+        return matches.length === 1 ? getTableKey(matches[0]) : name;
+      });
+    }
+  }
+  loadCustomRelationships();
+  loadMatchData();
+  updateRelationshipDraftDefaults();
+  loadingDiagram.value = false;
+  await nextTick();
+  if (!active()) return;
+  await restoreOrInitializeLayout(active);
+  if (active()) graphStore.clearHistory();
+}
+
+async function handleToggleShowAllTables(): Promise<void> {
+  if (loadingDiagram.value || !focusedRoots.value.length) return;
+  await loadDiagram({ mode: showAllTables.value ? "focused" : "full" });
+}
+
 /** Restore saved table positions, or run layer-aware LTR layout when none exist. */
-async function restoreOrInitializeLayout() {
+async function restoreOrInitializeLayout(active: () => boolean = () => true) {
   const schemaKey = effectiveSchemaKey.value;
   const tableKeys = tables.value.map((t) => getTableKey(t));
   const tableNames = tables.value.map((t) => t.name);
@@ -1534,7 +1589,7 @@ async function restoreOrInitializeLayout() {
     const next: Record<string, DiagramPosition> = {};
     for (const table of tables.value) {
       const key = getTableKey(table);
-      const pos = savedPositions[key] || savedPositions[table.name];
+      const pos = savedPositions[key] || (canUseUnqualifiedTableName(table) ? savedPositions[table.name] : undefined);
       if (pos) next[key] = { ...pos };
     }
     positions.value = next;
@@ -1547,13 +1602,13 @@ async function restoreOrInitializeLayout() {
     return;
   }
 
-  await applyInitialLayerAwareLayout();
+  await applyInitialLayerAwareLayout(active);
 }
 
 /** Place tables that have no saved position into their layer (or canvas grid). */
 function fillMissingTablePositions() {
   const heights = tableHeightsMap();
-  const missing = tables.value.filter((t) => !positions.value[getTableKey(t)] && !positions.value[t.name]);
+  const missing = tables.value.filter((t) => !positions.value[getTableKey(t)]);
   if (missing.length === 0) return;
 
   for (const table of missing) {
@@ -1596,8 +1651,9 @@ function fillMissingTablePositions() {
   }
 }
 
-async function applyInitialLayerAwareLayout() {
+async function applyInitialLayerAwareLayout(active: () => boolean = () => true) {
   await nextTick();
+  if (!active()) return;
   const layoutTables = canvasVisibleTables.value;
   if (layoutTables.length === 0) {
     syncVueFlowNodes();
@@ -1606,7 +1662,7 @@ async function applyInitialLayerAwareLayout() {
 
   // Free layers with no member positions cannot preserve relative layout — treat as auto for init.
   const layersForLayout = layerStore.layers
-    .filter((l) => l.visible)
+    .filter((l) => l.visible && canLayoutLayer(l))
     .map((l) => {
       const hasMemberPos = l.tableNames.some((name) => positions.value[name]);
       if ((l.layoutMode ?? "auto") === "free" && !hasMemberPos) {
@@ -1616,7 +1672,7 @@ async function applyInitialLayerAwareLayout() {
     });
 
   const result = computeLtrAutoLayout({
-    tables: layoutTables,
+    tables: layoutTables.map((table) => ({ ...table, name: getTableKey(table) })),
     positions: positions.value,
     layers: layersForLayout,
     paneWidth: diagramPaneWidth(),
@@ -1632,7 +1688,7 @@ async function applyInitialLayerAwareLayout() {
     if (result.positions[table.name] && !nextPositions[key]) {
       nextPositions[key] = result.positions[table.name];
     }
-    if (result.positions[key] && !nextPositions[table.name]) {
+    if (result.positions[key] && !nextPositions[table.name] && canUseUnqualifiedTableName(table)) {
       nextPositions[table.name] = result.positions[key];
     }
   }
@@ -1660,10 +1716,17 @@ function requestRefreshDiagram() {
 
 function confirmRefreshDiagram() {
   showRefreshConfirm.value = false;
-  void loadDiagram();
+  void loadDiagram({ force: true });
 }
 
 async function initialize() {
+  namespaceGeneration++;
+  const generation = ++initializationGeneration;
+  diagramLoadGeneration++;
+  loadingDiagram.value = false;
+  loadingDatabases.value = false;
+  loadingSchemas.value = false;
+  persistedTableSnapshot = [];
   connectionId.value = "";
   database.value = "";
   schema.value = "";
@@ -1687,9 +1750,26 @@ async function initialize() {
   graphStore.setNodes([]);
   graphStore.setEdges([]);
 
+  if (props.prefillConnectionId && props.prefillDatabase && (props.focusTableName || props.focusTableNames?.length)) {
+    const names = props.focusTableNames?.length ? props.focusTableNames : [props.focusTableName!];
+    const namespace = diagramNamespaceSnapshots.get(JSON.stringify([props.prefillConnectionId, props.prefillDatabase, props.prefillCatalog]));
+    const rootSchema = props.prefillSchema || namespace?.defaultSchema || props.prefillDatabase;
+    const request = { connectionId: props.prefillConnectionId, database: props.prefillDatabase, catalog: props.prefillCatalog, roots: names.map((name) => ({ name, schema: rootSchema })) };
+    if (namespace && getFocusedDiagramCache(focusedDiagramCacheKey(request))) {
+      connectionId.value = request.connectionId;
+      database.value = request.database;
+      schema.value = rootSchema;
+      databases.value = [...namespace.databases];
+      schemas.value = [...namespace.schemas];
+      selectedSchemas.value = [rootSchema];
+      await loadDiagram();
+      return;
+    }
+  }
   if (props.prefillConnectionId) {
     connectionId.value = props.prefillConnectionId;
     await loadDatabases(props.prefillConnectionId);
+    if (!open.value || generation !== initializationGeneration) return;
     const initialDatabase = props.prefillDatabase && databases.value.includes(props.prefillDatabase) ? props.prefillDatabase : props.prefillDatabase || databases.value[0] || "";
     if (initialDatabase) await setDatabase(initialDatabase);
     return;
@@ -2051,6 +2131,22 @@ function handleKeyup(e: KeyboardEvent) {
   }
 }
 
+watch(
+  diagramContextKey,
+  () => {
+    diagramLoadGeneration++;
+    loadingDiagram.value = false;
+  },
+  { flush: "sync" },
+);
+
+watch(
+  () => [props.prefillConnectionId, props.prefillDatabase, props.prefillSchema, props.prefillCatalog, props.focusTableName, JSON.stringify(props.focusTableNames)],
+  () => {
+    if (open.value) void initialize();
+  },
+);
+
 watch(
   open,
   (value) => {
@@ -2058,6 +2154,10 @@ watch(
       void initialize();
       void setupFullscreenListeners();
     } else {
+      diagramLoadGeneration++;
+      initializationGeneration++;
+      namespaceGeneration++;
+      loadingDiagram.value = false;
       teardownFullscreenListeners();
       if (diagramOwnedFullscreen) {
         void exitFullscreen();
@@ -2108,6 +2208,9 @@ onMounted(() => {
 });
 
 onUnmounted(() => {
+  diagramLoadGeneration++;
+  initializationGeneration++;
+  namespaceGeneration++;
   window.removeEventListener("keydown", handleKeydown);
   window.removeEventListener("keyup", handleKeyup);
   if (engineeringViewportFrame !== null) {
@@ -2156,7 +2259,7 @@ onUnmounted(() => {
         :show-match-panel="showMatchPanel"
         :show-layers-panel="showLayersPanel"
         :show-all-tables="showAllTables"
-        :focus-table-name="focusTableName ?? ''"
+        :focus-table-name="focusedRoots[0]?.name ?? ''"
         :generated-join-sql="generatedJoinSql"
         :is-fullscreen="isFullscreen"
         :draft-table-count="draftTableCount"
@@ -2171,7 +2274,7 @@ onUnmounted(() => {
         @toggle-match-panel="handleToggleMatchPanel"
         @toggle-layers-panel="showLayersPanel = !showLayersPanel"
         @copy-join-sql="copyJoinSql"
-        @toggle-show-all-tables="showAllTables = !showAllTables"
+        @toggle-show-all-tables="handleToggleShowAllTables"
         @export-format="exportDiagram"
         @refresh="requestRefreshDiagram"
         @zoom-out="zoomOut"
@@ -2200,7 +2303,7 @@ onUnmounted(() => {
           </div>
           <ResizerHandle v-if="showLayersPanel && diagramReady" @resize="handleLeftResize" />
           <div class="min-h-0 flex-1 overflow-hidden">
-            <div v-if="loadingDiagram" class="h-full flex items-center justify-center text-sm text-muted-foreground">
+            <div v-if="loadingDiagram && tables.length === 0" class="h-full flex items-center justify-center text-sm text-muted-foreground">
               <Loader2 class="mr-2 h-4 w-4 animate-spin" />
               {{ loadingText }}
             </div>
diff --git a/apps/desktop/src/components/diagram/__tests__/DiagramToolbar.spec.ts b/apps/desktop/src/components/diagram/__tests__/DiagramToolbar.spec.ts
index 8eb3da9093..f9ffd78e68 100644
--- a/apps/desktop/src/components/diagram/__tests__/DiagramToolbar.spec.ts
+++ b/apps/desktop/src/components/diagram/__tests__/DiagramToolbar.spec.ts
@@ -82,6 +82,7 @@ afterEach(() => {
 function mountToolbar() {
   const search = ref("");
   const updates: string[] = [];
+  const refreshes: number[] = [];
   const host = document.createElement("div");
   document.body.append(host);
   const app = createApp(
@@ -100,7 +101,7 @@ function mountToolbar() {
             loadingDatabases: false,
             loadingSchemas: false,
             loadingDiagram: false,
-            diagramReady: false,
+            diagramReady: true,
             tablesCount: 0,
             relationshipsCount: 0,
             customRelationshipCount: 0,
@@ -116,13 +117,14 @@ function mountToolbar() {
               updates.push(value);
               search.value = value;
             },
+            onRefresh: () => refreshes.push(Date.now()),
           });
       },
     }),
   );
   app.mount(host);
   mountedApps.push({ app, host });
-  return { host, search, updates };
+  return { host, search, updates, refreshes };
 }
 
 describe("DiagramToolbar", () => {
@@ -142,4 +144,16 @@ describe("DiagramToolbar", () => {
     expect(search.value).toBe("user");
     expect(input.value).toBe("user");
   });
+
+  it("renders exactly one existing Refresh control and emits one refresh action", async () => {
+    const { host, refreshes } = mountToolbar();
+    await nextTick();
+
+    const refreshButtons = host.querySelectorAll<HTMLButtonElement>('button[title="diagram.refresh"]');
+    expect(refreshButtons).toHaveLength(1);
+    refreshButtons[0].click();
+    await nextTick();
+
+    expect(refreshes).toHaveLength(1);
+  });
 });
diff --git a/apps/desktop/src/components/diagram/__tests__/SchemaDiagramLoading.spec.ts b/apps/desktop/src/components/diagram/__tests__/SchemaDiagramLoading.spec.ts
new file mode 100644
index 0000000000..b8ac8dd0c1
--- /dev/null
+++ b/apps/desktop/src/components/diagram/__tests__/SchemaDiagramLoading.spec.ts
@@ -0,0 +1,298 @@
+// @vitest-environment happy-dom
+import { createApp, nextTick, reactive, type App } from "vue";
+import { createPinia } from "pinia";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { clearFocusedDiagramCacheForTests } from "@/lib/diagram/diagramMetadataCache";
+import { loadDraftTables, loadLiveTablePatches, loadPersistedLayers, loadPersistedPositions, saveDraftTables, saveLiveTablePatches, savePersistedLayers, savePersistedPositions } from "@/lib/diagram/draft-storage";
+import type { DiagramTable } from "@/lib/diagram/erDiagram";
+import type { ColumnInfo, ForeignKeyInfo, IndexInfo } from "@/types/database";
+
+const mocks = vi.hoisted(() => ({
+  ensureConnected: vi.fn(async () => {}),
+  toast: vi.fn(),
+  listDatabases: vi.fn(async () => [{ name: "db" }]),
+  listSchemas: vi.fn(async () => ["public", "other"]),
+  listTables: vi.fn(async () => ["A", "B", "C", "unrelated"].map((name) => ({ name, table_type: "TABLE" }))),
+  getColumns: vi.fn(async () => [{ name: "id", data_type: "int", is_nullable: false, is_primary_key: true, column_default: null, extra: null }]),
+  listForeignKeys: vi.fn(async (_id: string, _db: string, _schema: string, name: string): Promise<ForeignKeyInfo[]> => (name === "A" || name === "B" ? [{ name: "fk", column: "id", ref_table: name === "A" ? "B" : "C", ref_column: "id" }] : [])),
+  listForeignKeysForDatabase: vi.fn(async () => ({})),
+  listIndexes: vi.fn(async () => []),
+  getTableComment: vi.fn(async () => null),
+}));
+vi.mock("@/lib/backend/api", () => mocks);
+vi.mock("vue-i18n", () => ({ useI18n: () => ({ t: (key: string) => key }) }));
+vi.mock("@/composables/useToast", () => ({ useToast: () => ({ toast: mocks.toast }) }));
+vi.mock("@/stores/connectionStore", () => ({ useConnectionStore: () => ({ connections: [{ id: "c", db_type: "postgres" }], getConfig: () => ({ id: "c", db_type: "postgres" }), ensureConnected: mocks.ensureConnected }) }));
+vi.mock("@vue-flow/core", async () => {
+  const { ref } = await import("vue");
+  return {
+    VueFlow: {},
+    useVueFlow: () => {
+      const nodes = ref([]);
+      const edges = ref([]);
+      return {
+        nodes,
+        edges,
+        setNodes: (value: []) => {
+          nodes.value = value;
+        },
+        setEdges: (value: []) => {
+          edges.value = value;
+        },
+        fitView: vi.fn(),
+        getViewport: () => ({ x: 0, y: 0, zoom: 1 }),
+      };
+    },
+  };
+});
+vi.mock("../DiagramInspector.vue", () => ({ default: {} }));
+vi.mock("../DiagramSyncDialog.vue", () => ({ default: {} }));
+vi.mock("../CreateDraftTableDialog.vue", () => ({ default: {} }));
+vi.mock("../TableNode.vue", () => ({ default: {} }));
+vi.mock("../LayerNode.vue", () => ({ default: {} }));
+vi.mock("../RelationshipEdge.vue", () => ({ default: {} }));
+vi.mock("../MatchPanel.vue", () => ({ default: {} }));
+vi.mock("../DiagramToolbar.vue", () => ({ default: {} }));
+vi.mock("../LayerPanel.vue", () => ({ default: {} }));
+import SchemaDiagramDialog from "../SchemaDiagramDialog.vue";
+
+const mounted: App[] = [];
+async function settle() {
+  for (let i = 0; i < 40; i++) {
+    await Promise.resolve();
+    await nextTick();
+  }
+}
+function deferred<T>() {
+  let resolve!: (value: T) => void;
+  let reject!: (error: Error) => void;
+  const promise = new Promise<T>((a, b) => {
+    resolve = a;
+    reject = b;
+  });
+  return { promise, resolve, reject };
+}
+
+async function mountDialog(focused = true, overrides: { focusTableNames?: string[]; prefillSchema?: string } = {}) {
+  const props = reactive({ open: true, prefillConnectionId: "c", prefillDatabase: "db", prefillSchema: "public", prefillCatalog: "catalog", focusTableName: focused ? "A" : "", ...overrides });
+  // Exercise the actual SFC setup, watchers, loaders and layout/persistence with the canvas renderer omitted.
+  const app = createApp({ ...SchemaDiagramDialog, render: () => null }, props);
+  app.use(createPinia());
+  const instance = app.mount(document.createElement("div"));
+  mounted.push(app);
+  const state = instance.$.setupState as any;
+  await settle();
+  return { app, state, props };
+}
+
+beforeEach(() => {
+  clearFocusedDiagramCacheForTests();
+  localStorage.clear();
+  vi.clearAllMocks();
+});
+afterEach(() => {
+  for (const app of mounted.splice(0)) app.unmount();
+});
+
+describe("diagram loading integration", () => {
+  it("loads the recursive closure without listing tables and passes catalog", async () => {
+    const { state } = await mountDialog();
+    expect(state.tables.map((table: DiagramTable) => table.name)).toEqual(["A", "B", "C"]);
+    expect(state.visibleTables).toHaveLength(3);
+    expect(mocks.listTables).not.toHaveBeenCalled();
+    expect(mocks.getColumns).toHaveBeenCalledWith("c", "db", "public", "C", "catalog");
+    expect(mocks.listForeignKeys).toHaveBeenCalledTimes(3);
+    expect(mocks.listForeignKeysForDatabase).not.toHaveBeenCalled();
+    expect(state.loadingDiagram).toBe(false);
+  });
+
+  it("reopens from cache without any remote metadata or connection requests", async () => {
+    await mountDialog();
+    vi.clearAllMocks();
+    const { state } = await mountDialog();
+    expect(state.tables).toHaveLength(3);
+    expect(state.loadedTableCount).toBe(3);
+    expect(state.totalTableCount).toBe(3);
+    expect(state.loadingDiagram).toBe(false);
+    for (const method of [mocks.getColumns, mocks.listForeignKeys, mocks.listIndexes, mocks.getTableComment, mocks.listTables, mocks.listDatabases, mocks.listSchemas, mocks.ensureConnected]) expect(method).not.toHaveBeenCalled();
+  });
+
+  it("retains full-schema loading when opened without a root", async () => {
+    const { state } = await mountDialog(false);
+    expect(mocks.listTables).toHaveBeenCalledTimes(1);
+    expect(state.tables).toHaveLength(4);
+  });
+
+  it("loads a deduplicated union of multiple roots", async () => {
+    const { state } = await mountDialog(true, { focusTableNames: ["A", "B", "unrelated"] });
+    expect(state.tables.map((table: DiagramTable) => table.name)).toEqual(["A", "B", "C", "unrelated"]);
+    expect(mocks.getColumns).toHaveBeenCalledTimes(4);
+    expect(mocks.listTables).not.toHaveBeenCalled();
+  });
+
+  it("reuses cached default-schema roots when no schema was prefilled", async () => {
+    await mountDialog(true, { prefillSchema: undefined });
+    vi.clearAllMocks();
+    expect((await mountDialog(true, { prefillSchema: undefined })).state.tables).toHaveLength(3);
+    expect(mocks.listSchemas).not.toHaveBeenCalled();
+    expect(mocks.getColumns).not.toHaveBeenCalled();
+  });
+
+  it("initial metadata failure leaves an empty diagram and retries without a partial cache", async () => {
+    mocks.listIndexes.mockRejectedValueOnce(new Error("indexes offline"));
+    const { state } = await mountDialog();
+    expect(state.tables).toEqual([]);
+    expect(state.loadingDiagram).toBe(false);
+    expect(mocks.toast).toHaveBeenCalledWith("indexes offline", 5000);
+    vi.clearAllMocks();
+    expect((await mountDialog()).state.tables).toHaveLength(3);
+    expect(mocks.getColumns).toHaveBeenCalledTimes(3);
+  });
+
+  it("Show all tables loads full metadata and switching back reuses the focused cache", async () => {
+    const { state } = await mountDialog();
+    await state.handleToggleShowAllTables();
+    expect(state.showAllTables).toBe(true);
+    expect(state.tables).toHaveLength(4);
+    expect(mocks.listTables).toHaveBeenCalledTimes(1);
+    vi.clearAllMocks();
+    await state.handleToggleShowAllTables();
+    expect(state.showAllTables).toBe(false);
+    expect(state.tables).toHaveLength(3);
+    expect(mocks.getColumns).not.toHaveBeenCalled();
+  });
+
+  it("confirmation bypasses cache while failure keeps the previous diagram and cache", async () => {
+    const { state } = await mountDialog();
+    const oldTables = state.tables;
+    const pending = deferred<never>();
+    mocks.listForeignKeys.mockImplementationOnce(() => pending.promise);
+    state.requestRefreshDiagram();
+    expect(state.showRefreshConfirm).toBe(true);
+    state.confirmRefreshDiagram();
+    await settle();
+    expect(state.tables).toBe(oldTables);
+    expect(state.loadingDiagram).toBe(true);
+    pending.reject(new Error("offline"));
+    await settle();
+    expect(state.tables).toBe(oldTables);
+    expect(state.loadingDiagram).toBe(false);
+    expect(mocks.toast).toHaveBeenCalledWith("offline", 5000);
+    vi.clearAllMocks();
+    const reopened = await mountDialog();
+    expect(reopened.state.tables).toHaveLength(3);
+    expect(mocks.getColumns).not.toHaveBeenCalled();
+  });
+
+  it("successful refresh replaces the cached closure", async () => {
+    const { state } = await mountDialog();
+    mocks.listForeignKeys.mockResolvedValueOnce([]);
+    state.confirmRefreshDiagram();
+    await settle();
+    expect(state.tables.map((table: DiagramTable) => table.name)).toEqual(["A"]);
+    vi.clearAllMocks();
+    expect((await mountDialog()).state.tables).toHaveLength(1);
+    expect(mocks.getColumns).not.toHaveBeenCalled();
+  });
+
+  it("refresh fetches and applies the latest columns, indexes, and foreign keys before replacing the cache", async () => {
+    const { state } = await mountDialog();
+    vi.clearAllMocks();
+    const refreshedColumns: ColumnInfo[] = [
+      { name: "id", data_type: "int", is_nullable: false, is_primary_key: true, column_default: null, extra: null },
+      { name: "refreshed_column", data_type: "text", is_nullable: true, is_primary_key: false, column_default: null, extra: null },
+    ];
+    const refreshedIndexes: IndexInfo[] = [{ name: "ux_refreshed", columns: ["refreshed_column"], is_unique: true, is_primary: false }];
+    const refreshedForeignKeys: ForeignKeyInfo[] = [{ name: "fk_refreshed", column: "id", ref_table: "D", ref_column: "id" }];
+    mocks.getColumns.mockResolvedValueOnce(refreshedColumns);
+    mocks.listIndexes.mockResolvedValueOnce(refreshedIndexes);
+    mocks.listForeignKeys.mockResolvedValueOnce(refreshedForeignKeys);
+
+    state.confirmRefreshDiagram();
+    await settle();
+
+    expect(mocks.getColumns).toHaveBeenCalledWith("c", "db", "public", "A", "catalog");
+    expect(mocks.listIndexes).toHaveBeenCalledWith("c", "db", "public", "A", "catalog");
+    expect(mocks.listForeignKeys).toHaveBeenCalledWith("c", "db", "public", "A", "catalog");
+    expect(mocks.listForeignKeysForDatabase).not.toHaveBeenCalled();
+    const refreshedRoot = state.tables.find((table: DiagramTable) => table.name === "A") as DiagramTable;
+    expect(refreshedRoot.columns.map((column) => column.name)).toEqual(["id", "refreshed_column"]);
+    expect(refreshedRoot.indexes?.map((index) => index.name)).toEqual(["ux_refreshed"]);
+    expect(refreshedRoot.foreignKeys).toEqual(refreshedForeignKeys);
+    expect(state.visibleRelationships).toEqual([expect.objectContaining({ name: "fk_refreshed", sourceTable: "A", targetTable: "D" })]);
+
+    vi.clearAllMocks();
+    const reopened = await mountDialog();
+    const cachedRoot = reopened.state.tables.find((table: DiagramTable) => table.name === "A") as DiagramTable;
+    expect(cachedRoot.columns.map((column) => column.name)).toEqual(["id", "refreshed_column"]);
+    expect(cachedRoot.indexes?.map((index) => index.name)).toEqual(["ux_refreshed"]);
+    expect(cachedRoot.foreignKeys).toEqual(refreshedForeignKeys);
+    for (const method of [mocks.getColumns, mocks.listIndexes, mocks.listForeignKeys, mocks.listForeignKeysForDatabase]) expect(method).not.toHaveBeenCalled();
+  });
+
+  it("qualifies same-name nodes from different schemas", async () => {
+    mocks.listForeignKeys.mockResolvedValueOnce([{ name: "fk", column: "id", ref_table: "A", ref_schema: "other", ref_column: "id" }]);
+    mocks.listForeignKeys.mockResolvedValueOnce([]);
+    const { state } = await mountDialog();
+    expect(state.isMultiSchema).toBe(true);
+    expect(state.tables.map((table: DiagramTable) => state.getTableKey(table))).toEqual(["other.A", "public.A"]);
+    expect(state.visibleRelationships[0]).toMatchObject({ sourceTable: "public.A", targetTable: "other.A" });
+    expect(state.positions["public.A"]).toBeDefined();
+    expect(state.positions["other.A"]).toBeDefined();
+    expect(state.positions["public.A"]).not.toEqual(state.positions["other.A"]);
+  });
+
+  it("a late response cannot replace a newer schema result or its loading state", async () => {
+    const { state } = await mountDialog();
+    const pending = deferred<never[]>();
+    mocks.getColumns.mockImplementationOnce(() => pending.promise);
+    const old = state.loadDiagram({ force: true });
+    await settle();
+    await state.setSchema("other");
+    expect(state.tables.every((table: DiagramTable) => table.schema === "other")).toBe(true);
+    const current = state.tables;
+    pending.resolve([]);
+    await old;
+    expect(state.tables).toBe(current);
+    expect(state.loadingDiagram).toBe(false);
+  });
+
+  it("ignores a pending result after closing the dialog", async () => {
+    const { state } = await mountDialog();
+    const pending = deferred<never[]>();
+    mocks.getColumns.mockImplementationOnce(() => pending.promise);
+    const load = state.loadDiagram({ force: true });
+    await settle();
+    state.open = false;
+    await settle();
+    const old = state.tables;
+    pending.resolve([]);
+    await load;
+    expect(state.tables).toBe(old);
+    expect(state.loadingDiagram).toBe(false);
+  });
+
+  it("opening, dragging, editing, and refreshing preserves unrelated persisted data", async () => {
+    const draft: DiagramTable = { name: "draft_elsewhere", schema: "public", origin: "draft", columns: [], foreignKeys: [] };
+    saveDraftTables([draft], "c", "db", "public");
+    saveLiveTablePatches([{ ...draft, name: "unrelated", origin: "live", pendingDrop: true }], "c", "db", "public");
+    savePersistedPositions({ unrelated: { x: 900, y: 800 } }, "c", "db", "public");
+    savePersistedLayers([{ id: "layer", name: "saved", color: "red", visible: true, collapsed: false, tableNames: ["unrelated"] }], "c", "db", "public");
+    const { state } = await mountDialog();
+    await state.handleNodeDragStop({ node: { id: "A", type: "table", position: { x: 12, y: 34 } } });
+    const root = state.tables.find((table: DiagramTable) => table.name === "A") as DiagramTable;
+    const pendingColumn: ColumnInfo = { name: "pending_note", data_type: "text", is_nullable: true, is_primary_key: false, column_default: null, extra: null };
+    state.handleInspectorUpdateTable({ ...root, columns: [...root.columns, pendingColumn], pendingColumnNames: [pendingColumn.name] });
+    await state.loadDiagram({ force: true });
+    expect(loadPersistedPositions("c", "db", "public").A).toEqual({ x: 12, y: 34 });
+    expect(
+      loadLiveTablePatches("c", "db", "public")
+        .find((patch) => patch.tableName === "A")
+        ?.pendingColumns.map((column) => column.name),
+    ).toEqual(["pending_note"]);
+    expect(loadDraftTables("c", "db", "public").map((table) => table.name)).toContain("draft_elsewhere");
+    expect(loadLiveTablePatches("c", "db", "public").find((patch) => patch.tableName === "unrelated")?.pendingDrop).toBe(true);
+    expect(loadPersistedPositions("c", "db", "public").unrelated).toEqual({ x: 900, y: 800 });
+    expect(loadPersistedLayers("c", "db", "public")[0].tableNames).toContain("unrelated");
+  });
+});
diff --git a/apps/desktop/src/components/layout/AppDialogs.vue b/apps/desktop/src/components/layout/AppDialogs.vue
index 4e3b23c869..1a21198243 100644
--- a/apps/desktop/src/components/layout/AppDialogs.vue
+++ b/apps/desktop/src/components/layout/AppDialogs.vue
@@ -284,6 +284,7 @@ watch(
     :prefill-connection-id="dialogs.diagramPrefillConnectionId.value"
     :prefill-database="dialogs.diagramPrefillDatabase.value"
     :prefill-schema="dialogs.diagramPrefillSchema.value"
+    :prefill-catalog="dialogs.diagramPrefillCatalog.value"
     :focus-table-name="dialogs.diagramFocusTableName.value"
     :focus-table-names="dialogs.diagramFocusTableNames.value"
     @open-target="emit('openDiagramTarget', $event)"
diff --git a/apps/desktop/src/components/objects/ObjectBrowser.vue b/apps/desktop/src/components/objects/ObjectBrowser.vue
index 0ecd4d9846..fcc775968f 100644
--- a/apps/desktop/src/components/objects/ObjectBrowser.vue
+++ b/apps/desktop/src/components/objects/ObjectBrowser.vue
@@ -3225,6 +3225,7 @@ function openDiagram(row: ObjectBrowserRow) {
   connectionStore.diagramSource = {
     connectionId: props.connection.id,
     database: props.database,
+    catalog: props.catalog,
     schema: row.schema || selectedSchema.value,
     tableName: row.type === "TABLE" ? row.name : undefined,
   };
diff --git a/apps/desktop/src/composables/useDialogSources.ts b/apps/desktop/src/composables/useDialogSources.ts
index 6d1ca2e6ca..d10b7aebfd 100644
--- a/apps/desktop/src/composables/useDialogSources.ts
+++ b/apps/desktop/src/composables/useDialogSources.ts
@@ -75,6 +75,7 @@ const sqlFilePrefillPreview = ref<SqlFilePreview>();
 const diagramPrefillConnectionId = ref("");
 const diagramPrefillDatabase = ref("");
 const diagramPrefillSchema = ref("");
+const diagramPrefillCatalog = ref<string>();
 const diagramFocusTableName = ref("");
 const diagramFocusTableNames = ref<string[]>([]);
 const docsPrefillConnectionId = ref("");
@@ -257,6 +258,7 @@ export function useDialogSources() {
           diagramPrefillConnectionId.value = v.connectionId;
           diagramPrefillDatabase.value = v.database;
           diagramPrefillSchema.value = v.schema ?? "";
+          diagramPrefillCatalog.value = v.catalog;
           diagramFocusTableName.value = v.tableName ?? "";
           diagramFocusTableNames.value = v.tableNames ?? (v.tableName ? [v.tableName] : []);
           showDiagramDialog.value = true;
@@ -668,6 +670,7 @@ export function useDialogSources() {
     diagramPrefillConnectionId,
     diagramPrefillDatabase,
     diagramPrefillSchema,
+    diagramPrefillCatalog,
     diagramFocusTableName,
     diagramFocusTableNames,
     docsPrefillConnectionId,
diff --git a/apps/desktop/src/composables/useSidebarTreeToolRuntime.ts b/apps/desktop/src/composables/useSidebarTreeToolRuntime.ts
index 852c2929fa..5abf0cda3d 100644
--- a/apps/desktop/src/composables/useSidebarTreeToolRuntime.ts
+++ b/apps/desktop/src/composables/useSidebarTreeToolRuntime.ts
@@ -82,6 +82,7 @@ export function useSidebarTreeToolRuntime(options: SidebarTreeToolRuntimeOptions
     connectionStore.diagramSource = {
       connectionId: node.connectionId,
       database: node.database,
+      catalog: node.catalog,
       schema: node.schema,
       tableName: tableNames?.length ? tableNames[0] : node.type === "table" ? node.label : undefined,
       tableNames,
diff --git a/apps/desktop/src/lib/diagram/__tests__/diagramFocusedStorage.spec.ts b/apps/desktop/src/lib/diagram/__tests__/diagramFocusedStorage.spec.ts
new file mode 100644
index 0000000000..23e3654a0e
--- /dev/null
+++ b/apps/desktop/src/lib/diagram/__tests__/diagramFocusedStorage.spec.ts
@@ -0,0 +1,83 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { applyLiveTablePatches, loadDraftTables, loadLiveTablePatches, loadPersistedLayers, loadPersistedPositions, saveDraftTables, saveFocusedDiagramState, saveLiveTablePatches, savePersistedLayers, savePersistedPositions } from "../draft-storage";
+import type { DiagramTable } from "../erDiagram";
+
+const context = ["c", "db", "public"] as const;
+const live = (name: string, schema = "public"): DiagramTable => ({ name, schema, columns: [], foreignKeys: [] });
+const draft = (name: string): DiagramTable => ({ ...live(name), origin: "draft" });
+beforeEach(() => {
+  const values = new Map<string, string>();
+  vi.stubGlobal("localStorage", { getItem: (key: string) => values.get(key) ?? null, setItem: (key: string, value: string) => values.set(key, value) });
+});
+afterEach(() => vi.unstubAllGlobals());
+
+describe("focused persistence", () => {
+  it("opening, moving, and refreshing a subset preserves unrelated drafts, patches, layers, and positions", () => {
+    saveDraftTables([draft("unrelated_draft")], ...context);
+    saveLiveTablePatches([{ ...live("unrelated"), pendingDrop: true }], ...context);
+    savePersistedPositions({ unrelated: { x: 100, y: 200 } }, ...context);
+    const layers = [{ id: "layer", name: "saved", tableNames: ["root", "unrelated"], color: "red", visible: true, collapsed: false }];
+    savePersistedLayers(layers, ...context);
+    const root = live("root");
+    for (const positions of [{}, { root: { x: 12, y: 34 } }, {}]) saveFocusedDiagramState([root], [root], positions, [{ ...layers[0], tableNames: ["root"] }], ...context);
+    expect(loadDraftTables(...context).map((table) => table.name)).toEqual(["unrelated_draft"]);
+    expect(loadLiveTablePatches(...context)[0].tableName).toBe("unrelated");
+    expect(loadPersistedPositions(...context)).toEqual({ unrelated: { x: 100, y: 200 }, root: { x: 12, y: 34 } });
+    expect(loadPersistedLayers(...context)[0].tableNames).toEqual(["root", "unrelated"]);
+  });
+
+  it("upserts and removes only the edited live patch, keeping same-name patches in other schemas", () => {
+    const root = live("root");
+    saveLiveTablePatches(
+      [
+        { ...live("root", "other"), pendingDrop: true },
+        { ...live("unrelated"), pendingDrop: true },
+      ],
+      ...context,
+    );
+    const edited = { ...root, pendingDrop: true };
+    saveFocusedDiagramState([edited], [root], {}, [], ...context);
+    expect(loadLiveTablePatches(...context)).toHaveLength(3);
+    saveFocusedDiagramState([root], [edited], {}, [], ...context);
+    expect(loadLiveTablePatches(...context).map((patch) => [patch.schema, patch.tableName])).toEqual([
+      ["other", "root"],
+      ["public", "unrelated"],
+    ]);
+  });
+
+  it("creates, renames and deletes only the affected draft", () => {
+    saveDraftTables([draft("unrelated")], ...context);
+    const first = draft("new");
+    const renamed = draft("renamed");
+    saveFocusedDiagramState([first], [], {}, [], ...context);
+    saveFocusedDiagramState([renamed], [first], {}, [], ...context);
+    expect(loadDraftTables(...context).map((table) => table.name)).toEqual(["unrelated", "renamed"]);
+    saveFocusedDiagramState([], [renamed], {}, [], ...context);
+    expect(loadDraftTables(...context).map((table) => table.name)).toEqual(["unrelated"]);
+  });
+
+  it("retains unloaded membership even when the visible layer is removed", () => {
+    savePersistedLayers([{ id: "layer", name: "saved", tableNames: ["root", "unrelated"], color: "red", visible: true, collapsed: false }], ...context);
+    saveFocusedDiagramState([live("root")], [live("root")], {}, [], ...context);
+    expect(loadPersistedLayers(...context)[0].tableNames).toEqual(["unrelated"]);
+  });
+
+  it("applies qualified and legacy patches only to their schema", () => {
+    const tables = [live("root"), live("root", "other")];
+    const patches = [{ tableName: "root", pendingColumns: [], pendingDrop: true }];
+    expect(applyLiveTablePatches(tables, patches, "public").map((table) => !!table.pendingDrop)).toEqual([true, false]);
+    expect(applyLiveTablePatches(tables, [{ ...patches[0], schema: "other" }]).map((table) => !!table.pendingDrop)).toEqual([false, true]);
+  });
+
+  it("cross-schema edits preserve legacy state belonging to an unloaded root-schema table", () => {
+    const stored = { ...live("same"), schema: undefined, pendingDrop: true };
+    saveLiveTablePatches([stored], ...context);
+    savePersistedPositions({ same: { x: 100, y: 200 } }, ...context);
+    savePersistedLayers([{ id: "layer", name: "saved", tableNames: ["same"], color: "red", visible: true, collapsed: false }], ...context);
+    const other = live("same", "other");
+    saveFocusedDiagramState([{ ...other, pendingDrop: true }], [other], { same: { x: 1, y: 2 }, "other.same": { x: 3, y: 4 } }, [], ...context);
+    expect(loadLiveTablePatches(...context)).toHaveLength(2);
+    expect(loadPersistedPositions(...context).same).toEqual({ x: 100, y: 200 });
+    expect(loadPersistedLayers(...context)[0].tableNames).toEqual(["same"]);
+  });
+});
diff --git a/apps/desktop/src/lib/diagram/__tests__/diagramMetadataCache.spec.ts b/apps/desktop/src/lib/diagram/__tests__/diagramMetadataCache.spec.ts
new file mode 100644
index 0000000000..c585bc9d89
--- /dev/null
+++ b/apps/desktop/src/lib/diagram/__tests__/diagramMetadataCache.spec.ts
@@ -0,0 +1,124 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { clearFocusedDiagramCacheForTests, DIAGRAM_METADATA_CACHE_TTL_MS, focusedDiagramCacheKey, getFocusedDiagramCache, invalidateFocusedDiagramCache, loadFocusedDiagramCached, setFocusedDiagramCache } from "../diagramMetadataCache";
+import type { DiagramTable } from "../erDiagram";
+
+const tables = (name = "A"): DiagramTable[] => [{ name, schema: "public", columns: [], foreignKeys: [], indexes: [] }];
+function deferred<T>() {
+  let resolve!: (value: T) => void;
+  const promise = new Promise<T>((done) => {
+    resolve = done;
+  });
+  return { promise, resolve };
+}
+
+beforeEach(() => {
+  clearFocusedDiagramCacheForTests();
+  vi.useFakeTimers();
+  vi.setSystemTime(0);
+});
+afterEach(() => vi.useRealTimers());
+
+describe("five minute closure cache", () => {
+  it("loads once within TTL and expires exactly at five minutes", async () => {
+    const loader = vi.fn(async () => tables());
+    await loadFocusedDiagramCached("key", loader);
+    vi.advanceTimersByTime(DIAGRAM_METADATA_CACHE_TTL_MS - 1);
+    await loadFocusedDiagramCached("key", loader);
+    expect(loader).toHaveBeenCalledTimes(1);
+    vi.advanceTimersByTime(1);
+    await loadFocusedDiagramCached("key", loader);
+    expect(loader).toHaveBeenCalledTimes(2);
+  });
+
+  it("deduplicates concurrent callers and gives each a separate snapshot", async () => {
+    const pending = deferred<DiagramTable[]>();
+    const loader = vi.fn(() => pending.promise);
+    const a = loadFocusedDiagramCached("key", loader);
+    const b = loadFocusedDiagramCached("key", loader);
+    pending.resolve(tables());
+    const [first, second] = await Promise.all([a, b]);
+    expect(loader).toHaveBeenCalledTimes(1);
+    first[0].name = "edited";
+    expect(second[0].name).toBe("A");
+    expect(getFocusedDiagramCache("key")?.[0].name).toBe("A");
+  });
+
+  it("clones on storing and reading, including nested metadata", () => {
+    const original = tables();
+    setFocusedDiagramCache("key", original);
+    original[0].name = "changed";
+    const read = getFocusedDiagramCache("key")!;
+    read[0].foreignKeys.push({ name: "fk" } as never);
+    expect(getFocusedDiagramCache("key")).toEqual(tables());
+  });
+
+  it("does not cache errors and retries the next call", async () => {
+    const loader = vi.fn().mockRejectedValueOnce(new Error("offline")).mockResolvedValue(tables());
+    await expect(loadFocusedDiagramCached("key", loader)).rejects.toThrow("offline");
+    expect(getFocusedDiagramCache("key")).toBeUndefined();
+    await loadFocusedDiagramCached("key", loader);
+    expect(loader).toHaveBeenCalledTimes(2);
+  });
+
+  it("force bypasses cache, joins forced loads, and replaces only after success", async () => {
+    setFocusedDiagramCache("key", tables("old"));
+    const pending = deferred<DiagramTable[]>();
+    const loader = vi.fn(() => pending.promise);
+    const a = loadFocusedDiagramCached("key", loader, { force: true });
+    const b = loadFocusedDiagramCached("key", loader, { force: true });
+    expect(await loadFocusedDiagramCached("key", loader)).toEqual(tables("old"));
+    pending.resolve(tables("fresh"));
+    await Promise.all([a, b]);
+    expect(loader).toHaveBeenCalledTimes(1);
+    expect(getFocusedDiagramCache("key")).toEqual(tables("fresh"));
+  });
+
+  it("preserves valid cache after failed forced refresh", async () => {
+    setFocusedDiagramCache("key", tables("old"));
+    await expect(
+      loadFocusedDiagramCached(
+        "key",
+        async () => {
+          throw new Error("offline");
+        },
+        { force: true },
+      ),
+    ).rejects.toThrow("offline");
+    expect(getFocusedDiagramCache("key")).toEqual(tables("old"));
+  });
+
+  it("an older ordinary load cannot overwrite a newer forced result", async () => {
+    const pending = deferred<DiagramTable[]>();
+    const old = loadFocusedDiagramCached("key", () => pending.promise);
+    await loadFocusedDiagramCached("key", async () => tables("fresh"), { force: true });
+    pending.resolve(tables("old"));
+    await old;
+    expect(getFocusedDiagramCache("key")).toEqual(tables("fresh"));
+  });
+
+  it("invalidating in-flight work prevents later cache commits", async () => {
+    const pending = deferred<DiagramTable[]>();
+    const load = loadFocusedDiagramCached("key", () => pending.promise);
+    invalidateFocusedDiagramCache();
+    pending.resolve(tables());
+    await load;
+    expect(getFocusedDiagramCache("key")).toBeUndefined();
+  });
+
+  it("keys isolate connection, database, catalog, schemas, names, and root sets", () => {
+    const base = {
+      connectionId: "c",
+      database: "db",
+      roots: [
+        { schema: "public", name: "A" },
+        { schema: "public", name: "B" },
+      ],
+    };
+    const key = focusedDiagramCacheKey(base);
+    expect(focusedDiagramCacheKey({ ...base, roots: [...base.roots].reverse().concat(base.roots) })).toBe(key);
+    for (const change of [{ connectionId: "other" }, { database: "other" }, { catalog: "other" }, { roots: [{ schema: "other", name: "A" }] }, { roots: [base.roots[0]] }, { roots: [{ schema: "public", name: "a" }] }]) {
+      expect(focusedDiagramCacheKey({ ...base, ...change })).not.toBe(key);
+    }
+    expect(focusedDiagramCacheKey({ ...base, roots: [{ schema: "a.b", name: "c" }] })).not.toBe(focusedDiagramCacheKey({ ...base, roots: [{ schema: "a", name: "b.c" }] }));
+  });
+});
diff --git a/apps/desktop/src/lib/diagram/__tests__/diagramMetadataLoader.spec.ts b/apps/desktop/src/lib/diagram/__tests__/diagramMetadataLoader.spec.ts
new file mode 100644
index 0000000000..8b2dda64cb
--- /dev/null
+++ b/apps/desktop/src/lib/diagram/__tests__/diagramMetadataLoader.spec.ts
@@ -0,0 +1,73 @@
+import { describe, expect, it, vi } from "vitest";
+import { diagramIdentityKey, loadFocusedDiagram, type DiagramMetadataAdapter, type FocusedDiagramLoadRequest } from "../diagramMetadataLoader";
+import type { ForeignKeyInfo } from "@/types/database";
+
+const request = (names = ["A"]): FocusedDiagramLoadRequest => ({ connectionId: "c", database: "db", roots: names.map((name) => ({ schema: "public", name })) });
+const fk = (name: string, schema?: string): ForeignKeyInfo => ({ name: "fk", column: "id", ref_table: name, ref_schema: schema, ref_column: "id", on_update: "NO ACTION", on_delete: "NO ACTION" });
+function adapter(graph: Record<string, ForeignKeyInfo[]> = {}): DiagramMetadataAdapter {
+  return { getColumns: vi.fn(async () => []), listIndexes: vi.fn(async () => []), listForeignKeys: vi.fn(async (table) => graph[`${table.schema}.${table.name}`] ?? []), getTableComment: vi.fn(async () => "comment") };
+}
+
+describe("focused outbound metadata traversal", () => {
+  it.each([
+    ["leaf", {}, ["A"]],
+    ["chain", { "public.A": [fk("B")], "public.B": [fk("C")] }, ["A", "B", "C"]],
+    ["branch", { "public.A": [fk("C"), fk("B")] }, ["A", "B", "C"]],
+    ["cycle", { "public.A": [fk("B")], "public.B": [fk("A")] }, ["A", "B"]],
+    ["self reference", { "public.A": [fk("A")] }, ["A"]],
+    ["composite rows", { "public.A": [fk("B"), fk("B")] }, ["A", "B"]],
+  ] as const)("loads %s once without requesting unrelated tables", async (_name, graph, expected) => {
+    const metadata = adapter(graph);
+    const result = await loadFocusedDiagram(request(), metadata);
+    expect(result.tables.map((table) => table.name)).toEqual(expected);
+    for (const method of [metadata.getColumns, metadata.listForeignKeys, metadata.listIndexes, metadata.getTableComment]) expect(method).toHaveBeenCalledTimes(expected.length);
+    expect(result.rootKeys).toEqual([diagramIdentityKey({ schema: "public", name: "A" })]);
+  });
+
+  it("unions roots, deduplicates them, and preserves cross-schema and case identities", async () => {
+    const metadata = adapter({ "public.A": [fk("B"), fk("A", "other")], "public.B": [fk("A"), fk("a")] });
+    const result = await loadFocusedDiagram(request(["B", "A", "A"]), metadata);
+    expect(result.tables.map((table) => [table.schema, table.name])).toEqual([
+      ["other", "A"],
+      ["public", "A"],
+      ["public", "B"],
+      ["public", "a"],
+    ]);
+    expect(metadata.getColumns).toHaveBeenCalledTimes(4);
+  });
+
+  it.each(["getColumns", "listForeignKeys", "listIndexes"] as const)("rejects required %s failures", async (method) => {
+    const metadata = adapter();
+    metadata[method] = vi.fn().mockRejectedValue(new Error("offline"));
+    await expect(loadFocusedDiagram(request(), metadata)).rejects.toThrow("offline");
+  });
+
+  it("allows optional comment failures", async () => {
+    const metadata = adapter();
+    metadata.getTableComment = vi.fn().mockRejectedValue(new Error("unsupported"));
+    expect((await loadFocusedDiagram(request(), metadata)).tables[0].comment).toBeNull();
+  });
+
+  it("bounds table concurrency and reports a growing discovered count", async () => {
+    const metadata = adapter({ "public.A": [fk("B"), fk("C"), fk("D"), fk("E")], "public.B": [fk("F")] });
+    let running = 0;
+    let peak = 0;
+    metadata.getColumns = vi.fn(async () => {
+      running++;
+      peak = Math.max(peak, running);
+      await new Promise((resolve) => setTimeout(resolve, 1));
+      running--;
+      return [];
+    });
+    const onProgress = vi.fn();
+    await loadFocusedDiagram({ ...request(), concurrency: 2, onProgress }, metadata);
+    expect(peak).toBe(2);
+    expect(onProgress.mock.calls).toEqual([
+      [0, 1],
+      [1, 5],
+      [3, 6],
+      [5, 6],
+      [6, 6],
+    ]);
+  });
+});
diff --git a/apps/desktop/src/lib/diagram/diagramMetadataCache.ts b/apps/desktop/src/lib/diagram/diagramMetadataCache.ts
new file mode 100644
index 0000000000..a3f8baf82e
--- /dev/null
+++ b/apps/desktop/src/lib/diagram/diagramMetadataCache.ts
@@ -0,0 +1,66 @@
+import type { DiagramTable } from "./erDiagram";
+import { diagramIdentityKey, normalizedDiagramRoots, type FocusedDiagramLoadRequest } from "./diagramMetadataLoader";
+
+export const DIAGRAM_METADATA_CACHE_TTL_MS = 5 * 60 * 1000;
+interface CacheEntry {
+  cachedAt: number;
+  expiresAt: number;
+  tables: DiagramTable[];
+}
+interface PendingLoad {
+  force: boolean;
+  promise: Promise<DiagramTable[]>;
+}
+const entries = new Map<string, CacheEntry>();
+const inFlight = new Map<string, PendingLoad>();
+// Metadata is JSON data; this also accepts Vue reactive snapshots without proxy cloning errors.
+const clone = (tables: DiagramTable[]): DiagramTable[] => JSON.parse(JSON.stringify(tables));
+
+export function focusedDiagramCacheKey(request: FocusedDiagramLoadRequest): string {
+  return JSON.stringify({ version: 1, connectionId: request.connectionId, database: request.database, catalog: request.catalog ?? "", roots: normalizedDiagramRoots(request.roots).map(diagramIdentityKey), traversal: "outbound-fk" });
+}
+
+export function getFocusedDiagramCache(key: string, now = Date.now()): DiagramTable[] | undefined {
+  const entry = entries.get(key);
+  if (!entry) return undefined;
+  if (now >= entry.expiresAt) {
+    entries.delete(key);
+    return undefined;
+  }
+  return clone(entry.tables);
+}
+
+export function setFocusedDiagramCache(key: string, tables: DiagramTable[], now = Date.now()): void {
+  entries.set(key, { cachedAt: now, expiresAt: now + DIAGRAM_METADATA_CACHE_TTL_MS, tables: clone(tables) });
+}
+
+export async function loadFocusedDiagramCached(key: string, loader: () => Promise<DiagramTable[]>, options: { force?: boolean } = {}): Promise<DiagramTable[]> {
+  if (!options.force) {
+    const cached = getFocusedDiagramCache(key);
+    if (cached) return cached;
+  }
+  const existing = inFlight.get(key);
+  if (existing && (!options.force || existing.force)) return clone(await existing.promise);
+  const pending: PendingLoad = { force: !!options.force, promise: Promise.resolve([]) };
+  pending.promise = Promise.resolve()
+    .then(loader)
+    .then((tables) => {
+      // A forced request can supersede an older ordinary request without deleting its valid snapshot.
+      if (inFlight.get(key) === pending) setFocusedDiagramCache(key, tables);
+      return tables;
+    })
+    .finally(() => {
+      if (inFlight.get(key) === pending) inFlight.delete(key);
+    });
+  inFlight.set(key, pending);
+  return clone(await pending.promise);
+}
+
+export function invalidateFocusedDiagramCache(match: (key: string) => boolean = () => true): void {
+  for (const key of entries.keys()) if (match(key)) entries.delete(key);
+  for (const key of inFlight.keys()) if (match(key)) inFlight.delete(key);
+}
+
+export function clearFocusedDiagramCacheForTests(): void {
+  invalidateFocusedDiagramCache();
+}
diff --git a/apps/desktop/src/lib/diagram/diagramMetadataLoader.ts b/apps/desktop/src/lib/diagram/diagramMetadataLoader.ts
new file mode 100644
index 0000000000..90bc7ca872
--- /dev/null
+++ b/apps/desktop/src/lib/diagram/diagramMetadataLoader.ts
@@ -0,0 +1,92 @@
+import type { ColumnInfo, ForeignKeyInfo, IndexInfo } from "@/types/database";
+import type { DiagramTable } from "./erDiagram";
+
+export interface DiagramTableIdentity {
+  schema: string;
+  name: string;
+}
+
+export interface FocusedDiagramLoadRequest {
+  connectionId: string;
+  database: string;
+  catalog?: string;
+  roots: DiagramTableIdentity[];
+  concurrency?: number;
+  onProgress?: (loaded: number, discovered: number) => void;
+}
+
+export interface FocusedDiagramLoadResult {
+  tables: DiagramTable[];
+  rootKeys: string[];
+}
+
+export interface DiagramMetadataAdapter {
+  getColumns(table: DiagramTableIdentity): Promise<ColumnInfo[]>;
+  listForeignKeys(table: DiagramTableIdentity): Promise<ForeignKeyInfo[]>;
+  listIndexes(table: DiagramTableIdentity): Promise<IndexInfo[]>;
+  getTableComment?(table: DiagramTableIdentity): Promise<string | null>;
+}
+
+/** JSON tuples preserve case and cannot collide on dots in quoted identifiers. */
+export function diagramIdentityKey(table: { schema?: string; name: string }): string {
+  return JSON.stringify([table.schema ?? "", table.name]);
+}
+
+export function normalizedDiagramRoots(roots: DiagramTableIdentity[]): DiagramTableIdentity[] {
+  return [...new Map(roots.filter((root) => root.name.trim()).map((root) => [diagramIdentityKey(root), { ...root }])).values()].sort(compareIdentities);
+}
+
+function compareIdentities(a: DiagramTableIdentity, b: DiagramTableIdentity): number {
+  return a.schema < b.schema ? -1 : a.schema > b.schema ? 1 : a.name < b.name ? -1 : a.name > b.name ? 1 : 0;
+}
+
+/** Keep the same editable index representation used by the structure inspector. */
+export function diagramIndexes(indexes: IndexInfo[]): DiagramTable["indexes"] {
+  return indexes.map((index) => ({
+    id: index.name,
+    name: index.name,
+    columns: [...index.columns],
+    isUnique: index.is_unique,
+    isPrimary: index.is_primary,
+    filter: index.filter ?? "",
+    indexType: index.index_type ?? "",
+    includedColumns: index.included_columns ?? [],
+    comment: index.comment ?? "",
+    markedForDrop: false,
+    original: index,
+  }));
+}
+
+/** Bounded breadth-first outbound traversal. Required metadata errors reject the closure. */
+export async function loadFocusedDiagram(request: FocusedDiagramLoadRequest, metadata: DiagramMetadataAdapter): Promise<FocusedDiagramLoadResult> {
+  const roots = normalizedDiagramRoots(request.roots);
+  const rootKeys = roots.map(diagramIdentityKey);
+  const discovered = new Set(rootKeys);
+  const pending = [...roots];
+  const tables: DiagramTable[] = [];
+  const concurrency = Number.isFinite(request.concurrency) ? Math.max(1, Math.floor(request.concurrency!)) : 4;
+  request.onProgress?.(0, discovered.size);
+  while (pending.length) {
+    const batch = pending.splice(0, concurrency);
+    const batchTables = await Promise.all(
+      batch.map(async (table) => {
+        const [columns, foreignKeys, indexes, comment] = await Promise.all([metadata.getColumns(table), metadata.listForeignKeys(table), metadata.listIndexes(table), metadata.getTableComment?.(table).catch(() => null) ?? null]);
+        return { ...table, columns, foreignKeys, indexes: diagramIndexes(indexes), comment };
+      }),
+    );
+    for (const table of batchTables) {
+      tables.push(table);
+      for (const fk of table.foreignKeys) {
+        const target = { schema: fk.ref_schema || table.schema, name: fk.ref_table };
+        const key = diagramIdentityKey(target);
+        if (!discovered.has(key)) {
+          discovered.add(key);
+          pending.push(target);
+        }
+      }
+    }
+    request.onProgress?.(tables.length, discovered.size);
+  }
+  tables.sort((a, b) => compareIdentities({ schema: a.schema ?? "", name: a.name }, { schema: b.schema ?? "", name: b.name }));
+  return { tables, rootKeys };
+}
diff --git a/apps/desktop/src/lib/diagram/draft-storage.ts b/apps/desktop/src/lib/diagram/draft-storage.ts
index b6ce9fcee5..d585c996f0 100644
--- a/apps/desktop/src/lib/diagram/draft-storage.ts
+++ b/apps/desktop/src/lib/diagram/draft-storage.ts
@@ -3,9 +3,11 @@ import type { ColumnInfo } from "@/types/database";
 import type { DiagramPosition, DiagramTable } from "./erDiagram";
 import { isLiveTable, needsDiagramSync } from "./erDiagram";
 import type { DiagramLayer } from "@/types/diagram";
+import { diagramIdentityKey } from "./diagramMetadataLoader";
 
 export interface LiveTablePatch {
   tableName: string;
+  schema?: string;
   pendingColumns: ColumnInfo[];
   droppedColumnNames?: string[];
   pendingDrop?: boolean;
@@ -123,6 +125,7 @@ export function loadLiveTablePatches(connectionId: string, database: string, sch
       const droppedColumnNames = sanitizeStringList(patch.droppedColumnNames);
       const next: LiveTablePatch = {
         tableName: patch.tableName,
+        schema: patch.schema,
         pendingColumns: pendingColumns.map((col) => ({ ...col })),
       };
       if (droppedColumnNames.length) next.droppedColumnNames = droppedColumnNames;
@@ -134,6 +137,10 @@ export function loadLiveTablePatches(connectionId: string, database: string, sch
 export function saveLiveTablePatches(tables: DiagramTable[], connectionId: string, database: string, schema: string): void {
   if (!connectionId || !database) return;
   const key = storageKey("live-patches", connectionId, database, schema);
+  safeLocalStorageSet(key, JSON.stringify(liveTablePatches(tables)));
+}
+
+function liveTablePatches(tables: DiagramTable[]): LiveTablePatch[] {
   const patches: LiveTablePatch[] = [];
   for (const table of tables) {
     if (!isLiveTable(table) || !needsDiagramSync(table)) continue;
@@ -143,22 +150,58 @@ export function saveLiveTablePatches(tables: DiagramTable[], connectionId: strin
     if (pendingColumns.length === 0 && droppedColumnNames.length === 0 && !table.pendingDrop) continue;
     const patch: LiveTablePatch = {
       tableName: table.name,
+      schema: table.schema,
       pendingColumns: pendingColumns.map((col) => ({ ...col })),
     };
     if (droppedColumnNames.length) patch.droppedColumnNames = droppedColumnNames;
     if (table.pendingDrop) patch.pendingDrop = true;
     patches.push(patch);
   }
-  safeLocalStorageSet(key, JSON.stringify(patches));
+  return patches;
+}
+
+/** Persist only edits since the last applied snapshot, never the absent part of a focused schema. */
+export function saveFocusedDiagramState(tables: DiagramTable[], previousTables: DiagramTable[], positions: Record<string, DiagramPosition>, layers: DiagramLayer[], connectionId: string, database: string, schema: string, legacySchema = schema): void {
+  if (!connectionId || !database) return;
+  const previous = new Map(previousTables.map((table) => [diagramIdentityKey(table), table]));
+  const current = new Map(tables.map((table) => [diagramIdentityKey(table), table]));
+  const changed = new Set([...previous.keys(), ...current.keys()].filter((key) => JSON.stringify(previous.get(key)) !== JSON.stringify(current.get(key))));
+  if (changed.size) {
+    const drafts = loadDraftTables(connectionId, database, schema).filter((table) => !changed.has(diagramIdentityKey(table)));
+    saveDraftTables([...drafts, ...tables.filter((table) => changed.has(diagramIdentityKey(table)))], connectionId, database, schema);
+    const oldPatches = loadLiveTablePatches(connectionId, database, schema).filter(
+      (patch) =>
+        ![...changed].some((key) => {
+          const table = current.get(key) ?? previous.get(key)!;
+          return patch.tableName === table.name && (patch.schema === table.schema || (patch.schema === undefined && (!table.schema || table.schema === legacySchema)));
+        }),
+    );
+    const newPatches = liveTablePatches(tables.filter((table) => changed.has(diagramIdentityKey(table))));
+    safeLocalStorageSet(storageKey("live-patches", connectionId, database, schema), JSON.stringify([...oldPatches, ...newPatches]));
+  }
+  const loadedNames = new Set([...previousTables, ...tables].flatMap((table) => (!table.schema || table.schema === legacySchema ? [table.name, table.schema ? `${table.schema}.${table.name}` : table.name] : [`${table.schema}.${table.name}`])));
+  const scopedPositions = Object.fromEntries(Object.entries(positions).filter(([name]) => loadedNames.has(name)));
+  savePersistedPositions({ ...loadPersistedPositions(connectionId, database, schema), ...scopedPositions }, connectionId, database, schema);
+  const mergedLayers = layers.map((layer) => ({ ...layer, tableNames: [...layer.tableNames] }));
+  for (const stored of loadPersistedLayers(connectionId, database, schema)) {
+    const unloadedMembers = stored.tableNames.filter((name) => !loadedNames.has(name));
+    const next = mergedLayers.find((layer) => layer.id === stored.id);
+    if (next) next.tableNames = [...new Set([...next.tableNames, ...unloadedMembers])];
+    else if (unloadedMembers.length || stored.tableNames.length === 0) mergedLayers.push({ ...stored, tableNames: unloadedMembers });
+  }
+  savePersistedLayers(mergedLayers, connectionId, database, schema);
 }
 
 /** Merge saved pending adds/drops onto live tables loaded from DB metadata. */
-export function applyLiveTablePatches(tables: DiagramTable[], patches: LiveTablePatch[]): DiagramTable[] {
+export function applyLiveTablePatches(tables: DiagramTable[], patches: LiveTablePatch[], legacySchema?: string): DiagramTable[] {
   if (patches.length === 0) return tables;
-  const byName = new Map(patches.map((p) => [p.tableName, p]));
+  const byName = new Map(patches.map((p) => [diagramIdentityKey({ name: p.tableName, schema: p.schema ?? legacySchema }), p]));
+  const nameCounts = new Map<string, number>();
+  for (const table of tables) nameCounts.set(table.name, (nameCounts.get(table.name) ?? 0) + 1);
   return tables.map((table) => {
     if (!isLiveTable(table)) return table;
-    const patch = byName.get(table.name);
+    const unambiguous = nameCounts.get(table.name) === 1;
+    const patch = byName.get(diagramIdentityKey(table)) ?? (unambiguous ? byName.get(diagramIdentityKey({ name: table.name })) : undefined);
     if (!patch) return table;
 
     const existing = new Set(table.columns.map((c) => c.name.toLowerCase()));
diff --git a/apps/desktop/src/stores/connectionStore.ts b/apps/desktop/src/stores/connectionStore.ts
index 379feb91b3..7e1e82973f 100644
--- a/apps/desktop/src/stores/connectionStore.ts
+++ b/apps/desktop/src/stores/connectionStore.ts
@@ -641,6 +641,7 @@ export const useConnectionStore = defineStore("connection", () => {
     connectionId: string;
     database: string;
     schema?: string;
+    catalog?: string;
     tableName?: string;
     tableNames?: string[];
   } | null>(null);
diff --git a/packages/app-tests/diagramRefreshConfirm.test.ts b/packages/app-tests/diagramRefreshConfirm.test.ts
index 108f92e8df..431ab20d60 100644
--- a/packages/app-tests/diagramRefreshConfirm.test.ts
+++ b/packages/app-tests/diagramRefreshConfirm.test.ts
@@ -15,10 +15,7 @@ describe("diagram refresh confirmation wiring", () => {
     assert.match(dialogSource, /function requestRefreshDiagram\(\)/);
     assert.match(dialogSource, /showRefreshConfirm\.value = true/);
     assert.match(dialogSource, /@refresh="requestRefreshDiagram"/);
-    assert.match(
-      dialogSource,
-      /DangerConfirmDialog[^>]*v-model:open="showRefreshConfirm"[^>]*@confirm="confirmRefreshDiagram"/,
-    );
-    assert.match(dialogSource, /function confirmRefreshDiagram\(\)[\s\S]*?void loadDiagram\(\)/);
+    assert.match(dialogSource, /DangerConfirmDialog[^>]*v-model:open="showRefreshConfirm"[^>]*@confirm="confirmRefreshDiagram"/);
+    assert.match(dialogSource, /function confirmRefreshDiagram\(\)[\s\S]*?void loadDiagram\(\{ force: true \}\)/);
   });
 });