diff --git a/TODO.md b/TODO.md
index 1f03251..115dabb 100644
--- a/TODO.md
+++ b/TODO.md
@@ -213,8 +213,8 @@ Pure tab-policy helpers that decide:
   - `titleStrategy`: shared title resolver hooks
 
 ## Phase 4 — Editor Routing Registry
-- Replace long `if/else` tab-type rendering chain with declarative tab->component mapping.
-- Keep special cases explicit (e.g., tab ID transforms such as git-diff commit/file parsing).
+- [x] Replace long `if/else` tab-type rendering chain with declarative tab->component mapping.
+- [x] Keep special cases explicit (e.g., tab ID transforms such as git-diff commit/file parsing).
 
 ## Phase 5 — Menu/Event Harmonization
 - Route menu-driven view/tab actions through the same behavior layer where applicable.
@@ -258,4 +258,5 @@ Pure tab-policy helpers that decide:
 - [x] Phase 3 continuation slice complete: migrated post/media open paths in Sidebar, Editor, LinkedMediaPanel, and Panel to shared entity-tab policy.
 - [x] Phase 3 completion slice: centralized `chat` and `import` tab-open specs and migrated sidebar call sites.
 - [x] Phase 3 completion slice: centralized `git-diff` file/commit ID/spec/open helpers and reused shared parsing in `TabBar`.
-- [ ] Next implementation slice: Phase 4 (editor routing registry).
+- [x] Phase 4 complete: introduced `editorRouting` registry/resolver and migrated `Editor` to declarative route->view rendering.
+- [ ] Next implementation slice: Phase 5 (menu/event harmonization).
diff --git a/src/renderer/components/Editor/Editor.tsx b/src/renderer/components/Editor/Editor.tsx
index aeb91c7..9bc0c0f 100644
--- a/src/renderer/components/Editor/Editor.tsx
+++ b/src/renderer/components/Editor/Editor.tsx
@@ -22,6 +22,7 @@ import { AutoSaveManager, getContrastColor } from '../../utils';
 import { InsertModal } from '../InsertModal';
 import { AISuggestionsModal, AISuggestions } from '../AISuggestionsModal/AISuggestionsModal';
 import { openEntityTab } from '../../navigation/tabPolicy';
+import { EditorRoute, resolveEditorRoute } from '../../navigation/editorRouting';
 import { useI18n } from '../../i18n';
 import './Editor.css';
 
@@ -1724,20 +1725,7 @@ export const Editor: React.FC = () => {
   // Get the active tab
   const activeTab = tabs.find(t => t.id === activeTabId);
 
-  // Determine what to show based on active tab
-  // Settings and tags should only show when their tab is active, not based on activeView
-  // (activeView controls the sidebar, not the main content area)
-  const showPost = activeTab?.type === 'post';
-  const showMedia = activeTab?.type === 'media';
-  const showSettings = activeTab?.type === 'settings';
-  const showStyle = activeTab?.type === 'style';
-  const showTags = activeTab?.type === 'tags';
-  const showChat = activeTab?.type === 'chat';
-  const showImport = activeTab?.type === 'import';
-  const showMetadataDiff = activeTab?.type === 'metadata-diff';
-  const showGitDiff = activeTab?.type === 'git-diff';
-  const showDocumentation = activeTab?.type === 'documentation';
-  const showSiteValidation = activeTab?.type === 'site-validation';
+  const editorRoute = resolveEditorRoute(activeTab);
 
   useEffect(() => {
     const activePostId = activeTab?.type === 'post' ? activeTab.id : null;
@@ -1789,129 +1777,30 @@ export const Editor: React.FC = () => {
     <ConfirmDeleteModal details={confirmDeleteModal} onClose={hideConfirmDeleteModal} />
   );
 
-  // Show settings only if settings tab is active
-  if (showSettings) {
-    return (
-      <div className="editor">
-        <SettingsView />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
+  const editorViewRenderers: Record<EditorRoute, () => React.ReactNode> = {
+    settings: () => <SettingsView />,
+    style: () => <StyleView />,
+    tags: () => <TagsView />,
+    chat: () => (editorRoute.tabId ? <ChatPanel key={editorRoute.tabId} conversationId={editorRoute.tabId} /> : <Dashboard />),
+    import: () =>
+      editorRoute.tabId ? <ImportAnalysisView key={editorRoute.tabId} definitionId={editorRoute.tabId} /> : <Dashboard />,
+    'metadata-diff': () => <MetadataDiffPanel />,
+    'git-diff': () =>
+      editorRoute.tabId && editorRoute.gitDiffResource
+        ? <GitDiffView key={editorRoute.tabId} filePath={editorRoute.gitDiffResource} />
+        : <Dashboard />,
+    documentation: () => <DocumentationView />,
+    'site-validation': () => <SiteValidationView />,
+    post: () => (editorRoute.tabId ? <PostEditor key={editorRoute.tabId} postId={editorRoute.tabId} /> : <Dashboard />),
+    media: () => (editorRoute.tabId ? <MediaEditor key={editorRoute.tabId} mediaId={editorRoute.tabId} /> : <Dashboard />),
+    dashboard: () => <Dashboard />,
+  };
 
-  if (showStyle) {
-    return (
-      <div className="editor">
-        <StyleView />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
+  const editorContent = editorViewRenderers[editorRoute.route]();
 
-  // Show tags if tags tab is active
-  if (showTags) {
-    return (
-      <div className="editor">
-        <TagsView />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
-
-  // Show chat if chat tab is active
-  if (showChat && activeTabId) {
-    return (
-      <div className="editor">
-        <ChatPanel key={activeTabId} conversationId={activeTabId} />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
-
-  // Show import analysis if import tab is active
-  if (showImport && activeTabId) {
-    return (
-      <div className="editor">
-        <ImportAnalysisView key={activeTabId} definitionId={activeTabId} />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
-
-  // Show metadata diff if metadata-diff tab is active
-  if (showMetadataDiff) {
-    return (
-      <div className="editor">
-        <MetadataDiffPanel />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
-
-  // Show git diff view if git-diff tab is active
-  if (showGitDiff && activeTabId) {
-    const filePath = activeTabId.startsWith('git-diff:') ? activeTabId.slice('git-diff:'.length) : activeTabId;
-    return (
-      <div className="editor">
-        <GitDiffView key={activeTabId} filePath={filePath} />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
-
-  if (showDocumentation) {
-    return (
-      <div className="editor">
-        <DocumentationView />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
-
-  if (showSiteValidation) {
-    return (
-      <div className="editor">
-        <SiteValidationView />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
-
-  // Show post editor if a post tab is active
-  if (showPost && activeTabId) {
-    return (
-      <div className="editor">
-        <PostEditor key={activeTabId} postId={activeTabId} />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
-
-  // Show media editor if a media tab is active
-  if (showMedia && activeTabId) {
-    return (
-      <div className="editor">
-        <MediaEditor key={activeTabId} mediaId={activeTabId} />
-        {renderErrorModal()}
-        {renderConfirmDeleteModal()}
-      </div>
-    );
-  }
-
-  // No tab active - show dashboard
   return (
     <div className="editor">
-      <Dashboard />
+      {editorContent}
       {renderErrorModal()}
       {renderConfirmDeleteModal()}
     </div>
diff --git a/src/renderer/navigation/editorRouting.ts b/src/renderer/navigation/editorRouting.ts
new file mode 100644
index 0000000..5812ef4
--- /dev/null
+++ b/src/renderer/navigation/editorRouting.ts
@@ -0,0 +1,60 @@
+import type { Tab, TabType } from '../store/appStore';
+import { parseGitDiffTabId } from './tabPolicy';
+
+export type EditorRoute =
+  | 'dashboard'
+  | 'post'
+  | 'media'
+  | 'settings'
+  | 'style'
+  | 'tags'
+  | 'chat'
+  | 'import'
+  | 'metadata-diff'
+  | 'git-diff'
+  | 'documentation'
+  | 'site-validation';
+
+export const EDITOR_TAB_ROUTE_REGISTRY: Record<TabType, Exclude<EditorRoute, 'dashboard'>> = {
+  post: 'post',
+  media: 'media',
+  settings: 'settings',
+  style: 'style',
+  tags: 'tags',
+  chat: 'chat',
+  import: 'import',
+  'metadata-diff': 'metadata-diff',
+  'git-diff': 'git-diff',
+  documentation: 'documentation',
+  'site-validation': 'site-validation',
+};
+
+export interface EditorRouteResolution {
+  route: EditorRoute;
+  tabId: string | null;
+  gitDiffResource: string | null;
+}
+
+export function resolveEditorRoute(activeTab: Tab | undefined): EditorRouteResolution {
+  if (!activeTab) {
+    return {
+      route: 'dashboard',
+      tabId: null,
+      gitDiffResource: null,
+    };
+  }
+
+  if (activeTab.type === 'git-diff') {
+    return {
+      route: 'git-diff',
+      tabId: activeTab.id,
+      gitDiffResource: parseGitDiffTabId(activeTab.id).resource,
+    };
+  }
+
+  return {
+    route: EDITOR_TAB_ROUTE_REGISTRY[activeTab.type],
+    tabId: activeTab.id,
+    gitDiffResource: null,
+  };
+}
diff --git a/tests/renderer/navigation/editorRouting.test.ts b/tests/renderer/navigation/editorRouting.test.ts
new file mode 100644
index 0000000..86c85d8
--- /dev/null
+++ b/tests/renderer/navigation/editorRouting.test.ts
@@ -0,0 +1,63 @@
+import { describe, expect, it } from 'vitest';
+import type { Tab } from '../../../src/renderer/store/appStore';
+import {
+  EDITOR_TAB_ROUTE_REGISTRY,
+  resolveEditorRoute,
+} from '../../../src/renderer/navigation/editorRouting';
+
+describe('editorRouting', () => {
+  it('defines canonical tab-type to editor-route mapping', () => {
+    expect(EDITOR_TAB_ROUTE_REGISTRY).toEqual({
+      post: 'post',
+      media: 'media',
+      settings: 'settings',
+      style: 'style',
+      tags: 'tags',
+      chat: 'chat',
+      import: 'import',
+      'metadata-diff': 'metadata-diff',
+      'git-diff': 'git-diff',
+      documentation: 'documentation',
+      'site-validation': 'site-validation',
+    });
+  });
+
+  it('resolves dashboard route when no active tab is present', () => {
+    expect(resolveEditorRoute(undefined)).toEqual({
+      route: 'dashboard',
+      tabId: null,
+      gitDiffResource: null,
+    });
+  });
+
+  it('resolves post and media routes with active tab id', () => {
+    const postTab: Tab = { type: 'post', id: 'post-1', isTransient: true };
+    const mediaTab: Tab = { type: 'media', id: 'media-1', isTransient: false };
+
+    expect(resolveEditorRoute(postTab)).toEqual({
+      route: 'post',
+      tabId: 'post-1',
+      gitDiffResource: null,
+    });
+
+    expect(resolveEditorRoute(mediaTab)).toEqual({
+      route: 'media',
+      tabId: 'media-1',
+      gitDiffResource: null,
+    });
+  });
+
+  it('resolves git-diff route and extracts resource from tab id', () => {
+    const tab: Tab = {
+      type: 'git-diff',
+      id: 'git-diff:commit:abc123',
+      isTransient: true,
+    };
+
+    expect(resolveEditorRoute(tab)).toEqual({
+      route: 'git-diff',
+      tabId: 'git-diff:commit:abc123',
+      gitDiffResource: 'commit:abc123',
+    });
+  });
+});