feat: phase 3 for git integration

src/main/engine/GitEngine.ts

@@ -36,6 +36,11 @@ export interface GitStatusDto {
   counts: GitStatusCounts;
 }
 
+export interface GitDiffDto {
+  filePath: string;
+  patch: string;
+}
+
 export type GitInitPhase =
   | 'checking-git'
   | 'initializing-repo'
@@ -217,6 +222,16 @@ export class GitEngine {
     };
   }
 
+  async getDiff(projectPath: string, filePath: string): Promise<GitDiffDto> {
+    const git = simpleGit(projectPath);
+    const patch = await git.diff(['--', filePath]);
+
+    return {
+      filePath,
+      patch,
+    };
+  }
+
   async ensureGitignore(projectPath: string): Promise<GitIgnoreEnsureResult> {
     const gitignorePath = path.join(projectPath, '.gitignore');
 

src/main/engine/index.ts

@@ -79,6 +79,7 @@ export {
   type GitAvailability,
   type RepoState,
   type GitStatusDto,
+  type GitDiffDto,
   type GitStatusFile,
   type GitStatusCounts,
   type GitInitResult,

src/main/ipc/handlers.ts

@@ -48,6 +48,11 @@ export function registerIpcHandlers(): void {
     return engine.getStatus(projectPath);
   });
 
+  safeHandle('git:diff', async (_, projectPath: string, filePath: string) => {
+    const engine = getGitEngine();
+    return engine.getDiff(projectPath, filePath);
+  });
+
   safeHandle('git:init', async (event, projectPath: string, remoteUrl?: string) => {
     const engine = getGitEngine();
     return engine.initializeRepo(projectPath, remoteUrl, (progress) => {

src/main/preload.ts

@@ -10,6 +10,7 @@ export const electronAPI: ElectronAPI = {
     checkAvailability: () => ipcRenderer.invoke('git:checkAvailability'),
     getRepoState: (projectPath: string) => ipcRenderer.invoke('git:getRepoState', projectPath),
     getStatus: (projectPath: string) => ipcRenderer.invoke('git:status', projectPath),
+    getDiff: (projectPath: string, filePath: string) => ipcRenderer.invoke('git:diff', projectPath, filePath),
     ensureGitignore: (projectPath: string) => ipcRenderer.invoke('git:ensureGitignore', projectPath),
     pruneLfs: (projectPath: string, options?: { dryRun?: boolean; verifyRemote?: boolean }) => ipcRenderer.invoke('git:pruneLfs', projectPath, options),
     init: (projectPath: string, remoteUrl?: string) => {

src/main/shared/electronApi.ts

@@ -236,6 +236,11 @@ export interface GitStatusDto {
   counts: GitStatusCounts;
 }
 
+export interface GitDiffDto {
+  filePath: string;
+  patch: string;
+}
+
 export type GitInitPhase =
   | 'checking-git'
   | 'initializing-repo'
@@ -348,6 +353,7 @@ export interface ElectronAPI {
     checkAvailability: () => Promise<GitAvailability>;
     getRepoState: (projectPath: string) => Promise<GitRepoState>;
     getStatus: (projectPath: string) => Promise<GitStatusDto>;
+    getDiff: (projectPath: string, filePath: string) => Promise<GitDiffDto>;
     ensureGitignore: (projectPath: string) => Promise<GitIgnoreEnsureResult>;
     pruneLfs: (projectPath: string, options?: { dryRun?: boolean; verifyRemote?: boolean }) => Promise<GitLfsPruneResult>;
     init: (projectPath: string, remoteUrl?: string) => Promise<GitInitResult>;