diff --git a/packages/context/src/ingest/isolated-diff/source-routing.test.ts b/packages/context/src/ingest/isolated-diff/source-routing.test.ts
index 75e52a1c..0519a4a2 100644
--- a/packages/context/src/ingest/isolated-diff/source-routing.test.ts
+++ b/packages/context/src/ingest/isolated-diff/source-routing.test.ts
@@ -1,40 +1,22 @@
 import { describe, expect, it } from 'vitest';
-import {
-  defaultIsolatedDiffSourceKeys,
-  isIsolatedDiffDirectWriteSourceKey,
-  ISOLATED_DIFF_DIRECT_WRITE_SOURCE_KEYS,
-} from './source-routing.js';
+import { defaultSharedWorktreeSourceKeys, isSharedWorktreeFallbackSourceKey } from './source-routing.js';
 
 describe('isolated-diff source routing', () => {
-  it('keeps the runner-owned direct-write connector list explicit', () => {
-    expect(ISOLATED_DIFF_DIRECT_WRITE_SOURCE_KEYS).toEqual([
-      'metabase',
-      'notion',
-      'lookml',
-      'looker',
-      'dbt',
-      'metricflow',
-    ]);
+  it('defaults every non-override source to isolated diffs', () => {
+    expect(defaultSharedWorktreeSourceKeys()).toEqual([]);
   });
 
   it('returns a mutable copy for runtime settings', () => {
-    const keys = defaultIsolatedDiffSourceKeys();
-    keys.push('fake');
+    const keys = defaultSharedWorktreeSourceKeys();
+    keys.push('legacy-source');
 
-    expect(defaultIsolatedDiffSourceKeys()).toEqual([
-      'metabase',
-      'notion',
-      'lookml',
-      'looker',
-      'dbt',
-      'metricflow',
-    ]);
+    expect(defaultSharedWorktreeSourceKeys()).toEqual([]);
   });
 
-  it('recognizes migrated connector source keys only', () => {
-    expect(isIsolatedDiffDirectWriteSourceKey('notion')).toBe(true);
-    expect(isIsolatedDiffDirectWriteSourceKey('metricflow')).toBe(true);
-    expect(isIsolatedDiffDirectWriteSourceKey('historic-sql')).toBe(false);
-    expect(isIsolatedDiffDirectWriteSourceKey('live-database')).toBe(false);
+  it('recognizes only explicitly configured shared-worktree fallback sources', () => {
+    expect(isSharedWorktreeFallbackSourceKey('notion', [])).toBe(false);
+    expect(isSharedWorktreeFallbackSourceKey('metricflow', [])).toBe(false);
+    expect(isSharedWorktreeFallbackSourceKey('legacy-source', ['legacy-source'])).toBe(true);
+    expect(isSharedWorktreeFallbackSourceKey('other-source', ['legacy-source'])).toBe(false);
   });
 });
diff --git a/packages/context/src/ingest/isolated-diff/source-routing.ts b/packages/context/src/ingest/isolated-diff/source-routing.ts
index 20d63b89..52694304 100644
--- a/packages/context/src/ingest/isolated-diff/source-routing.ts
+++ b/packages/context/src/ingest/isolated-diff/source-routing.ts
@@ -1,22 +1,12 @@
-export const ISOLATED_DIFF_DIRECT_WRITE_SOURCE_KEYS = [
-  'metabase',
-  'notion',
-  'lookml',
-  'looker',
-  'dbt',
-  'metricflow',
-] as const;
+const DEFAULT_SHARED_WORKTREE_SOURCE_KEYS: readonly string[] = [];
 
-export type IsolatedDiffDirectWriteSourceKey = (typeof ISOLATED_DIFF_DIRECT_WRITE_SOURCE_KEYS)[number];
-
-const ISOLATED_DIFF_DIRECT_WRITE_SOURCE_KEY_SET = new Set<string>(ISOLATED_DIFF_DIRECT_WRITE_SOURCE_KEYS);
-
-export function defaultIsolatedDiffSourceKeys(): string[] {
-  return [...ISOLATED_DIFF_DIRECT_WRITE_SOURCE_KEYS];
+export function defaultSharedWorktreeSourceKeys(): string[] {
+  return [...DEFAULT_SHARED_WORKTREE_SOURCE_KEYS];
 }
 
-export function isIsolatedDiffDirectWriteSourceKey(
+export function isSharedWorktreeFallbackSourceKey(
   sourceKey: string,
-): sourceKey is IsolatedDiffDirectWriteSourceKey {
-  return ISOLATED_DIFF_DIRECT_WRITE_SOURCE_KEY_SET.has(sourceKey);
+  sharedWorktreeSourceKeys: readonly string[] = DEFAULT_SHARED_WORKTREE_SOURCE_KEYS,
+): boolean {
+  return sharedWorktreeSourceKeys.includes(sourceKey);
 }
diff --git a/packages/context/src/ingest/ports.ts b/packages/context/src/ingest/ports.ts
index 3527d29c..1131a672 100644
--- a/packages/context/src/ingest/ports.ts
+++ b/packages/context/src/ingest/ports.ts
@@ -143,7 +143,7 @@ export interface IngestSettingsPort {
   workUnitMaxConcurrency?: number;
   workUnitStepBudget?: number;
   workUnitFailureMode?: 'abort' | 'continue';
-  isolatedDiffSourceKeys?: string[];
+  sharedWorktreeSourceKeys?: string[];
   ingestTraceLevel?: IngestTraceLevel;
 }