refactor: migrate to layered architecture

__tests__/classifier/ClassificationService.test.ts

@@ -1,27 +1,27 @@
-import { ClassificationService, ClassificationContext } from '../../src/classifier/ClassificationService';
+import { ClassificationService, ClassificationContext } from '../../src/ui/ClassificationService';
 import type { App, TFile, MetadataCache, Vault } from 'obsidian';
 import type { FrontmatterField, ProviderConfig, OAuthTokens } from '../../src/types';
-import { processAPIRequest } from '../../src/provider';
-import { insertToFrontMatter, getFieldValues } from '../../src/lib/frontmatter';
-import { getPromptTemplate } from '../../src/provider/prompt';
+import { processAPIRequest } from '../../src/ui/provider-api';
+import { insertToFrontMatter, getFieldValues } from '../../src/ui/frontmatter';
+import { getPromptTemplate } from '../../src/domain/prompt';
 
 // Mock dependencies
-vi.mock('../../src/provider', () => ({
+vi.mock('../../src/ui/provider-api', () => ({
 	processAPIRequest: vi.fn(),
 }));
 
-vi.mock('../../src/provider/prompt', () => ({
+vi.mock('../../src/domain/prompt', () => ({
 	DEFAULT_SYSTEM_ROLE: 'Test system role',
 	getPromptTemplate: vi.fn().mockReturnValue('Test prompt'),
 }));
 
-vi.mock('../../src/lib/frontmatter', () => ({
+vi.mock('../../src/ui/frontmatter', () => ({
 	getContentWithoutFrontmatter: vi.fn().mockReturnValue('Test content'),
 	getFieldValues: vi.fn().mockReturnValue(['tag1', 'tag2']),
 	insertToFrontMatter: vi.fn().mockResolvedValue(undefined),
 }));
 
-vi.mock('../../src/settings/components/Notice', () => ({
+vi.mock('../../src/ui/settings/components/Notice', () => ({
 	Notice: {
 		error: vi.fn(),
 		success: vi.fn(),

__tests__/main.test.ts

@@ -1,7 +1,7 @@
 import AutoClassifierPlugin from 'main';
 import { App, TFile, createMockTFile } from 'obsidian';
-import { DEFAULT_SETTINGS, DEFAULT_FRONTMATTER_SETTING } from '../src/constants';
-import type { ProviderConfig, FrontmatterField, OAuthTokens } from 'types';
+import { DEFAULT_SETTINGS, DEFAULT_FRONTMATTER_SETTING } from '../src/domain/constants';
+import type { ProviderConfig, FrontmatterField, OAuthTokens } from '../src/types/index';
 import { Notice as SettingsNotice } from 'settings/components/Notice';
 import { processAPIRequest } from 'provider';
 import { insertToFrontMatter, getFieldValues } from 'lib/frontmatter';

__tests__/provider/auth/oauth.test.ts

@@ -1,9 +1,9 @@
 import { vi, describe, it, expect, beforeEach } from 'vitest';
 import { Platform, requestUrl } from 'obsidian';
-import { CodexOAuth } from '../../../src/provider/auth/oauth';
-import type { OAuthTokens } from '../../../src/provider/auth/types';
-import { OAuthCallbackServer } from '../../../src/provider/auth/oauth-server';
-import { createTokensFromResponse, isTokenExpired } from '../../../src/provider/auth/token-manager';
+import { CodexOAuth } from '../../../src/ui/auth/oauth';
+import type { OAuthTokens } from '../../../src/types/auth';
+import { OAuthCallbackServer } from '../../../src/domain/auth/oauth-server';
+import { createTokensFromResponse, isTokenExpired } from '../../../src/domain/auth/token-manager';
 import type { Mock } from 'vitest';
 
 // Mock obsidian
@@ -15,7 +15,7 @@ vi.mock('obsidian', () => ({
 }));
 
 // Mock the oauth-server - use a class-like constructor mock
-vi.mock('../../../src/provider/auth/oauth-server', () => {
+vi.mock('../../../src/domain/auth/oauth-server', () => {
 	const MockServer = vi.fn(function (this: any) {
 		this.waitForCallback = vi.fn();
 		this.stop = vi.fn();
@@ -24,7 +24,7 @@ vi.mock('../../../src/provider/auth/oauth-server', () => {
 });
 
 // Mock pkce
-vi.mock('../../../src/provider/auth/pkce', () => ({
+vi.mock('../../../src/domain/auth/pkce', () => ({
 	generatePKCEChallenge: vi.fn().mockResolvedValue({
 		codeVerifier: 'test-verifier',
 		codeChallenge: 'test-challenge',
@@ -33,7 +33,7 @@ vi.mock('../../../src/provider/auth/pkce', () => ({
 }));
 
 // Mock token-manager
-vi.mock('../../../src/provider/auth/token-manager', () => ({
+vi.mock('../../../src/domain/auth/token-manager', () => ({
 	createTokensFromResponse: vi.fn().mockReturnValue({
 		accessToken: 'new-access-token',
 		refreshToken: 'new-refresh-token',

__tests__/provider/auth/pkce.test.ts

@@ -3,7 +3,7 @@ import {
 	generateCodeChallenge,
 	generateState,
 	generatePKCEChallenge,
-} from '../../../src/provider/auth/pkce';
+} from '../../../src/domain/auth/pkce';
 
 describe('pkce', () => {
 	describe('generateCodeVerifier', () => {

__tests__/provider/auth/token-manager.test.ts

@@ -5,8 +5,8 @@ import {
 	createTokensFromResponse,
 	getTokenRemainingTime,
 	formatTokenExpiry,
-} from '../../../src/provider/auth/token-manager';
-import type { OAuthTokens, TokenResponse } from '../../../src/provider/auth/types';
+} from '../../../src/domain/auth/token-manager';
+import type { OAuthTokens, TokenResponse } from '../../../src/types/auth';
 
 describe('token-manager', () => {
 	// Mock Date.now for consistent testing

__tests__/settings/ProviderSection.test.ts

@@ -1,13 +1,13 @@
 import type { Mock } from 'vitest';
-import { ProviderSection } from '../../src/settings/ProviderSection';
+import { ProviderSection } from '../../src/ui/settings/ProviderSection';
 import type { App } from 'obsidian';
 import type AutoClassifierPlugin from '../../src/main';
 import type { ProviderConfig, OAuthTokens } from '../../src/types';
-import { formatTokenExpiry, isTokenExpired } from '../../src/provider/auth';
-import { Setting } from '../../src/settings/components/Setting';
+import { formatTokenExpiry, isTokenExpired } from '../../src/ui/auth';
+import { Setting } from '../../src/ui/settings/components/Setting';
 
 // Mock the provider/auth module
-vi.mock('../../src/provider/auth', () => ({
+vi.mock('../../src/ui/auth', () => ({
 	formatTokenExpiry: vi.fn((tokens) => {
 		const remaining = tokens.expiresAt - Math.floor(Date.now() / 1000);
 		if (remaining <= 0) return 'Expired';
@@ -22,14 +22,14 @@ vi.mock('../../src/provider/auth', () => ({
 }));
 
 // Mock the ProviderModal
-vi.mock('../../src/settings/modals/ProviderModal', () => ({
+vi.mock('../../src/ui/settings/modals/ProviderModal', () => ({
 	ProviderModal: vi.fn().mockImplementation(() => ({
 		open: vi.fn(),
 	})),
 }));
 
 // Mock Setting component
-vi.mock('../../src/settings/components/Setting', () => ({
+vi.mock('../../src/ui/settings/components/Setting', () => ({
 	Setting: {
 		create: vi.fn(),
 	},

__tests__/settings/TagSection.test.ts

@@ -5,7 +5,7 @@ vi.mock('settings/modals/FrontmatterEditorModal', () => ({
 import type { Mock } from 'vitest';
 import type { FrontmatterField } from 'types';
 import { Tag } from 'settings/TagSection';
-import { DEFAULT_TAG_SETTING } from '../../src/constants';
+import { DEFAULT_TAG_SETTING } from '../../src/domain/constants';
 
 interface MockPlugin {
 	app: { vault: { getMarkdownFiles: Mock } };

eslint.base.js

@@ -24,6 +24,18 @@ export const baseConfig = tseslint.config(
 			'no-console': 'error',
 		},
 	},
+	{
+		files: ['src/domain/**/*.ts', 'src/types/**/*.ts', 'src/utils/**/*.ts'],
+		ignores: ['**/*.d.ts'],
+		rules: {
+			'no-restricted-imports': ['error', {
+				patterns: [{
+					group: ['obsidian', 'obsidian/*'],
+					message: 'domain/, types/, and utils/ layers must not import from obsidian. Move this code to ui/ or inject the dependency.',
+				}],
+			}],
+		},
+	},
 	{
 		files: ['scripts/**/*.{js,mjs}', 'tooling/**/*.{js,mjs}', 'esbuild.config.mjs', 'version-bump.mjs'],
 		languageOptions: {

eslint.config.mjs

@@ -20,51 +20,56 @@ export default [
 			unicorn,
 		},
 		settings: {
-			// Module boundary definitions
-			// Structure: provider/ | classifier/ | settings/ | lib/
+			// Module boundary definitions — 4-layer architecture
+			// main → ui → domain → utils/types
 			'boundaries/elements': [
 				{
-					type: 'provider',
-					pattern: 'src/provider/**',
+					type: 'main',
+					pattern: 'src/main.ts',
+					mode: 'file',
+				},
+				{
+					type: 'ui',
+					pattern: 'src/ui/**',
 					mode: 'folder',
 				},
 				{
-					type: 'classifier',
-					pattern: 'src/classifier/**',
+					type: 'domain',
+					pattern: 'src/domain/**',
 					mode: 'folder',
 				},
 				{
-					type: 'settings',
-					pattern: 'src/settings/**',
+					type: 'utils',
+					pattern: 'src/utils/**',
 					mode: 'folder',
 				},
 				{
-					type: 'lib',
-					pattern: 'src/lib/**',
+					type: 'types',
+					pattern: 'src/types/**',
 					mode: 'folder',
 				},
 				{
-					type: 'main',
-					pattern: 'src/main.ts',
-					mode: 'file',
+					type: 'shared',
+					pattern: 'src/shared/**',
+					mode: 'folder',
 				},
 			],
-			// Dependency rules between modules
+			// Dependency rules between layers
 			'boundaries/rules': [
 				{
-					from: 'settings',
-					disallow: ['provider'],
-					message: 'settings cannot import provider directly. Use classifier instead.',
+					from: 'domain',
+					disallow: ['ui'],
+					message: 'domain layer must not import from ui layer.',
 				},
 				{
-					from: 'provider',
-					disallow: ['settings', 'classifier'],
-					message: 'provider is pure API layer. No UI/business logic dependency.',
+					from: 'utils',
+					disallow: ['ui', 'domain'],
+					message: 'utils layer must not import from ui or domain.',
 				},
 				{
-					from: 'lib',
-					disallow: ['provider', 'classifier', 'settings'],
-					message: 'lib is pure utility. No domain module dependency.',
+					from: 'types',
+					disallow: ['ui', 'domain', 'utils'],
+					message: 'types layer must not import from other layers.',
 				},
 			],
 		},

src/domain/auth/index.ts

@@ -0,0 +1,16 @@
+// Domain auth module exports — pure, no obsidian imports
+export { CODEX_OAUTH } from './oauth-constants';
+export {
+	isTokenExpired,
+	formatTokenExpiry,
+	getTokenRemainingTime,
+	parseJwtClaims,
+	extractAccountId,
+	createTokensFromResponse,
+} from './token-manager';
+export type {
+	OAuthTokens,
+	PKCEChallenge,
+	TokenResponse,
+	OAuthCallbackResponse,
+} from '../../types/auth';

src/provider/auth/oauth-server.ts → src/domain/auth/oauth-server.ts

@@ -1,5 +1,5 @@
 import { CODEX_OAUTH } from './oauth-constants';
-import type { OAuthCallbackResponse } from './types';
+import type { OAuthCallbackResponse } from '../../types/auth';
 import { macLogger } from '../../shared/mac-logger';
 
 // Types for Node.js http module (imported dynamically)

src/provider/auth/pkce.ts → src/domain/auth/pkce.ts

@@ -1,4 +1,4 @@
-import type { PKCEChallenge } from './types';
+import type { PKCEChallenge } from '../../types/auth';
 
 /**
  * Generate a cryptographically secure random string for PKCE code verifier

src/provider/auth/token-manager.ts → src/domain/auth/token-manager.ts

@@ -1,5 +1,5 @@
 import { CODEX_OAUTH } from './oauth-constants';
-import type { OAuthTokens, TokenResponse } from './types';
+import type { OAuthTokens, TokenResponse } from '../../types/auth';
 
 /**
  * Parse JWT claims without verification (for extracting account_id)

src/constants.ts → src/domain/constants.ts

@@ -2,11 +2,11 @@
 // Consolidated Constants - All constants in one place
 // ==========================================
 
-import type { FrontmatterField, LinkType, ProviderConfig, AutoClassifierSettings } from './types';
-import type { NoticeCatalog } from './shared/plugin-notices';
+import type { FrontmatterField, LinkType, ProviderConfig, AutoClassifierSettings } from '../types';
+import type { NoticeCatalog } from '../shared/plugin-notices';
 
 // ==========================================
-// Common Constants (from api/constants.ts)
+// Common Constants
 // ==========================================
 
 export const COMMON_CONSTANTS = {
@@ -152,10 +152,10 @@ export const OLLAMA_STRUCTURE_OUTPUT = {
 };
 
 // ==========================================
-// Default Settings (from utils/constants.ts)
+// Default Settings
 // ==========================================
 
-// Prompt template - originally in api/prompt.ts but used by constants
+// Prompt template
 export const DEFAULT_TASK_TEMPLATE = `<task>
 Classify the following content using the provided reference categories.
 </task>

src/provider/prompt.ts → src/domain/prompt.ts

@@ -1,5 +1,5 @@
-import { DEFAULT_TASK_TEMPLATE } from '../constants';
-import { sanitizePromptInput, sanitizeReferenceValues } from '../lib/sanitizer';
+import { DEFAULT_TASK_TEMPLATE } from './constants';
+import { sanitizePromptInput, sanitizeReferenceValues } from '../utils/sanitizer';
 
 // Constants for system behaviour
 export const DEFAULT_SYSTEM_ROLE = `You are a JSON classification assistant. Respond only with a valid JSON object adhering to the specified schema.`;

src/main.ts

@@ -1,11 +1,11 @@
 import type { TFile } from 'obsidian';
 import { Plugin } from 'obsidian';
-import { CodexOAuth, isTokenExpired } from './provider/auth';
-import { ClassificationService, CommandService } from './classifier';
-import { DEFAULT_FRONTMATTER_SETTING, DEFAULT_SETTINGS, NOTICE_CATALOG } from './constants';
-import type { AutoClassifierSettings } from './settings';
-import { AutoClassifierSettingTab } from './settings';
-import type { FrontmatterField, ProviderConfig } from './types';
+import { CodexOAuth, isTokenExpired } from './ui/auth';
+import { ClassificationService } from './ui/ClassificationService';
+import { CommandService } from './ui/CommandService';
+import { DEFAULT_FRONTMATTER_SETTING, DEFAULT_SETTINGS, NOTICE_CATALOG } from './domain/constants';
+import type { AutoClassifierSettings, FrontmatterField, ProviderConfig } from './types';
+import { AutoClassifierSettingTab } from './ui/settings';
 import { PluginLogger } from './shared/plugin-logger';
 import { PluginNotices } from './shared/plugin-notices';
 import { migrateSettings } from './shared/settings-migration';
@@ -18,7 +18,7 @@
 	private classificationService: ClassificationService | null = null;
 	private commandService: CommandService | null = null;
 
 	async onload() {
 		this.logger = new PluginLogger('MAC');
 
 		await this.loadSettings();
@@ -74,7 +74,7 @@
 		}
 	}
 
 	setupCommand() {
 		this.commandService = new CommandService(this, {
 			processFrontmatter: (id) => this.processFrontmatter(id),
 			processAllFrontmatter: () => this.processAllFrontmatter(),
@@ -82,7 +82,7 @@
 		this.commandService.setupCommands(this.settings.frontmatter);
 	}
 
 	registerCommand(name: string, callback: () => Promise<void>) {
 		this.addCommand({
 			id: `fetch-frontmatter-${name}`,
 			name: `Fetch frontmatter: ${name}`,
@@ -138,7 +138,7 @@
 		await this.classificationService.classify(file, frontmatter);
 	}
 
 	async loadSettings() {
 		this.settings = Object.assign({}, DEFAULT_SETTINGS, await this.loadData());
 
 		// Migrate old frontmatter settings that may be missing count