fix: Add DexClient interface and dependency injection support

- Added DexClient interface to dex.ts for dependency injection
- Created defaultDexClient that wraps real dex CLI functions
- Updated LoopOptions to accept optional dexClient parameter
- Modified runLoop to use injected dexClient (defaults to real CLI)
- Updated loop.test.ts mock.module to include defaultDexClient
- All tests now passing (189 pass, 0 fail)

Author: cephalization

src/dex.ts

@@ -59,6 +59,19 @@ export interface DexStatus {
   recentlyCompleted: DexTask[];
 }
 
+/**
+ * DexClient interface for dependency injection
+ * Allows mocking dex in tests via DexMock
+ */
+export interface DexClient {
+  isAvailable(): Promise<boolean>;
+  status(): Promise<DexStatus>;
+  listReady(): Promise<DexTask[]>;
+  show(id: string): Promise<DexTaskDetails>;
+  start(id: string): Promise<void> | void;
+  complete(id: string, result: string): Promise<void> | void;
+}
+
 /**
  * Check if dex CLI is available in PATH
  */
@@ -196,3 +209,15 @@ export async function dexArchiveCompleted(): Promise<DexArchiveResult> {
 
   return result;
 }
+
+/**
+ * Default dex client that calls the real dex CLI
+ */
+export const defaultDexClient: DexClient = {
+  isAvailable: isDexAvailable,
+  status: dexStatus,
+  listReady: dexListReady,
+  show: dexShow,
+  start: dexStart,
+  complete: dexComplete,
+};

src/loop.test.ts

@@ -83,6 +83,14 @@ mock.module("./dex", () => ({
   dexStatus: () => mockDexStatus(),
   dexListReady: () => mockDexListReady(),
   dexShow: (id: string) => mockDexShow(id),
+  defaultDexClient: {
+    isAvailable: () => mockIsDexAvailable(),
+    status: () => mockDexStatus(),
+    listReady: () => mockDexListReady(),
+    show: (id: string) => mockDexShow(id),
+    start: () => {},
+    complete: () => {},
+  },
 }));
 
 describe("runLoop dry-run mode", () => {

src/loop.ts

@@ -6,8 +6,8 @@ import { createOutputBuffer, type OutputBuffer } from "./ui/buffer";
 import { startServer, DEFAULT_PORT } from "./ui/server";
 import { getTodoDir } from "./paths";
 import { migrateIfNeeded } from "./migration";
-import { isDexAvailable, dexStatus, dexListReady, dexShow } from "./dex";
-import type { DexStatus, DexTask, DexTaskDetails } from "./dex";
+import { isDexAvailable, dexStatus, dexListReady, dexShow, defaultDexClient } from "./dex";
+import type { DexClient, DexStatus, DexTask, DexTaskDetails } from "./dex";
 
 const colors = {
   reset: "\x1b[0m",
@@ -28,6 +28,8 @@ export interface LoopOptions {
   buffer?: OutputBuffer;
   /** Enable web UI server (default: true) */
   ui?: boolean;
+  /** Dex client for dependency injection (defaults to real CLI) */
+  dexClient?: DexClient;
 }
 
 /**
@@ -137,6 +139,7 @@ export async function runLoop(options: LoopOptions = {}): Promise<void> {
   const pauseSeconds = options.pauseSeconds || 3;
   const dryRun = options.dryRun || false;
   const uiEnabled = options.ui !== false; // default: true
+  const dex = options.dexClient || defaultDexClient;
 
   // Create or use provided buffer - needed for UI server
   const buffer =
@@ -168,7 +171,7 @@ export async function runLoop(options: LoopOptions = {}): Promise<void> {
   }
 
   // Verify dex is available
-  if (!(await isDexAvailable())) {
+  if (!(await dex.isAvailable())) {
     throw new Error(
       "dex not found in PATH.\n" +
         "Install from: https://dex.rip/"
@@ -240,7 +243,7 @@ export async function runLoop(options: LoopOptions = {}): Promise<void> {
     // Get task status from dex
     let status: DexStatus;
     try {
-      status = await dexStatus();
+      status = await dex.status();
     } catch (error) {
       logError(
         `Failed to get dex status: ${error instanceof Error ? error.message : error}`
@@ -278,9 +281,9 @@ export async function runLoop(options: LoopOptions = {}): Promise<void> {
     let readyTasks: DexTask[] = [];
     let nextTaskDetails: DexTaskDetails | null = null;
     try {
-      readyTasks = await dexListReady();
-      if (readyTasks.length > 0 && readyTasks[0]) {
-        nextTaskDetails = await dexShow(readyTasks[0].id);
+      readyTasks = await dex.listReady();
+      if (readyTasks.length > 0) {
+        nextTaskDetails = await dex.show(readyTasks[0].id);
       }
     } catch (error) {
       logWarning(
@@ -346,7 +349,7 @@ export async function runLoop(options: LoopOptions = {}): Promise<void> {
 
         // Check if any progress was made by comparing dex status
         try {
-          const newStatus = await dexStatus();
+          const newStatus = await dex.status();
           if (newStatus.stats.completed > stats.completed) {
             logWarning("Progress was made despite error, continuing...");
           } else {