Make pull abort safely on conflicts

packages/server/src/utils/checkout-git.test.ts

@@ -1,6 +1,7 @@
 import { describe, it, expect, beforeEach, afterEach } from "vitest";
 import { execSync } from "child_process";
 import {
+  existsSync,
   mkdtempSync,
   rmSync,
   writeFileSync,
@@ -557,6 +558,63 @@ const x = 1;
     expect(readFileSync(join(repoDir, "pulled.txt"), "utf8")).toBe("remote\n");
   });
 
+  it("aborts pull on merge conflicts and leaves no merge in progress", async () => {
+    const remoteDir = join(tempDir, "remote.git");
+    execSync(`git init --bare -b main ${remoteDir}`);
+    execSync(`git remote add origin ${remoteDir}`, { cwd: repoDir });
+    execSync("git push -u origin main", { cwd: repoDir });
+
+    writeFileSync(join(repoDir, "conflict.txt"), "local\n");
+    execSync("git add conflict.txt", { cwd: repoDir });
+    execSync("git -c commit.gpgsign=false commit -m 'local conflict commit'", { cwd: repoDir });
+
+    const otherClone = join(tempDir, "other-clone");
+    execSync(`git clone ${remoteDir} ${otherClone}`);
+    execSync("git config user.email 'test@test.com'", { cwd: otherClone });
+    execSync("git config user.name 'Test'", { cwd: otherClone });
+    writeFileSync(join(otherClone, "conflict.txt"), "remote\n");
+    execSync("git add conflict.txt", { cwd: otherClone });
+    execSync("git -c commit.gpgsign=false commit -m 'remote conflict commit'", { cwd: otherClone });
+    execSync("git push", { cwd: otherClone });
+
+    await expect(pullCurrentBranch(repoDir)).rejects.toBeInstanceOf(Error);
+
+    const porcelain = execSync("git status --porcelain", { cwd: repoDir }).toString().trim();
+    expect(porcelain).toBe("");
+    expect(() => execSync("git rev-parse -q --verify MERGE_HEAD", { cwd: repoDir })).toThrow();
+  });
+
+  it("aborts pull on rebase conflicts and leaves no rebase in progress", async () => {
+    const remoteDir = join(tempDir, "remote.git");
+    execSync(`git init --bare -b main ${remoteDir}`);
+    execSync(`git remote add origin ${remoteDir}`, { cwd: repoDir });
+    execSync("git push -u origin main", { cwd: repoDir });
+    execSync("git config pull.rebase true", { cwd: repoDir });
+
+    writeFileSync(join(repoDir, "conflict.txt"), "local\n");
+    execSync("git add conflict.txt", { cwd: repoDir });
+    execSync("git -c commit.gpgsign=false commit -m 'local rebase conflict commit'", { cwd: repoDir });
+
+    const otherClone = join(tempDir, "other-clone");
+    execSync(`git clone ${remoteDir} ${otherClone}`);
+    execSync("git config user.email 'test@test.com'", { cwd: otherClone });
+    execSync("git config user.name 'Test'", { cwd: otherClone });
+    writeFileSync(join(otherClone, "conflict.txt"), "remote\n");
+    execSync("git add conflict.txt", { cwd: otherClone });
+    execSync("git -c commit.gpgsign=false commit -m 'remote rebase conflict commit'", {
+      cwd: otherClone,
+    });
+    execSync("git push", { cwd: otherClone });
+
+    await expect(pullCurrentBranch(repoDir)).rejects.toBeInstanceOf(Error);
+
+    const gitDir = execSync("git rev-parse --absolute-git-dir", { cwd: repoDir }).toString().trim();
+    const porcelain = execSync("git status --porcelain", { cwd: repoDir }).toString().trim();
+    expect(porcelain).toBe("");
+    expect(existsSync(join(gitDir, "rebase-merge"))).toBe(false);
+    expect(existsSync(join(gitDir, "rebase-apply"))).toBe(false);
+  });
+
   it("pushes the current branch to origin", async () => {
     const remoteDir = join(tempDir, "remote.git");
     execSync(`git init --bare -b main ${remoteDir}`);

packages/server/src/utils/checkout-git.ts

@@ -2,7 +2,7 @@ import { exec, execFile } from "child_process";
 import { spawnProcess } from "./spawn.js";
 import { promisify } from "util";
 import { resolve, dirname, basename } from "path";
-import { realpathSync } from "fs";
+import { existsSync, realpathSync } from "fs";
 import { open as openFile, stat as statFile } from "fs/promises";
 import { TTLCache } from "@isaacs/ttlcache";
 import type { ParsedDiffFile } from "../server/utils/diff-highlighter.js";
@@ -828,6 +828,46 @@ async function hasOriginRemote(cwd: string): Promise<boolean> {
   return url !== null;
 }
 
+async function resolveAbsoluteGitDir(cwd: string): Promise<string | null> {
+  try {
+    const { stdout } = await execAsync("git rev-parse --absolute-git-dir", {
+      cwd,
+      env: READ_ONLY_GIT_ENV,
+    });
+    const gitDir = stdout.trim();
+    return gitDir.length > 0 ? gitDir : null;
+  } catch {
+    return null;
+  }
+}
+
+async function abortGitPullConflictState(cwd: string): Promise<void> {
+  const gitDir = await resolveAbsoluteGitDir(cwd);
+  if (!gitDir) {
+    return;
+  }
+
+  const mergeHeadPath = resolve(gitDir, "MERGE_HEAD");
+  const rebaseMergePath = resolve(gitDir, "rebase-merge");
+  const rebaseApplyPath = resolve(gitDir, "rebase-apply");
+
+  if (existsSync(mergeHeadPath)) {
+    try {
+      await execAsync("git merge --abort", { cwd });
+    } catch {
+      // ignore
+    }
+  }
+
+  if (existsSync(rebaseMergePath) || existsSync(rebaseApplyPath)) {
+    try {
+      await execAsync("git rebase --abort", { cwd });
+    } catch {
+      // ignore
+    }
+  }
+}
+
 export async function resolveRepositoryDefaultBranch(repoRoot: string): Promise<string | null> {
   try {
     const { stdout } = await execAsync("git symbolic-ref --quiet refs/remotes/origin/HEAD", {
@@ -1463,6 +1503,13 @@ export async function getCheckoutDiff(
         continue;
       }
 
+      // `git diff -w --name-status` can still report a modified path even when the
+      // whitespace-filtered patch and numstat are both empty. Skip emitting a
+      // structured placeholder in that case so whitespace-only edits truly disappear.
+      if (ignoreWhitespace && !trackedDiffTruncated && stat === null) {
+        continue;
+      }
+
       structured.push({
         path: change.path,
         isNew: change.isNew,
@@ -1767,7 +1814,12 @@ export async function pullCurrentBranch(cwd: string): Promise<void> {
   if (!hasRemote) {
     throw new Error("Remote 'origin' is not configured.");
   }
-  await execAsync("git pull", { cwd });
+  try {
+    await execAsync("git pull", { cwd });
+  } catch (error) {
+    await abortGitPullConflictState(cwd);
+    throw error;
+  }
 }
 
 export async function pushCurrentBranch(cwd: string): Promise<void> {