diff --git a/packages/server/src/server/daemon-e2e/filesystem.e2e.test.ts b/packages/server/src/server/daemon-e2e/filesystem.e2e.test.ts
index 5a6187db71..7fee55e216 100644
--- a/packages/server/src/server/daemon-e2e/filesystem.e2e.test.ts
+++ b/packages/server/src/server/daemon-e2e/filesystem.e2e.test.ts
@@ -1,4 +1,4 @@
-import { describe, test, expect, beforeEach, afterEach } from "vitest";
+import { describe, test, expect, beforeEach, afterEach, onTestFinished } from "vitest";
 import {
   mkdtempSync,
   writeFileSync,
@@ -10,6 +10,7 @@ import {
 } from "fs";
 import { tmpdir } from "os";
 import path from "path";
+import { execFileSync } from "node:child_process";
 import { createDaemonTestContext, type DaemonTestContext } from "../test-utils/index.js";
 
 function tmpCwd(): string {
@@ -575,3 +576,63 @@ describe("file explorer", () => {
     rmSync(cwd, { recursive: true, force: true });
   }, 60000); // 1 minute timeout
 });
+
+describe("commit file diffs", () => {
+  test.each([".", "apps/web"])("opens committed files from %s workspaces", async (relativePath) => {
+    const cwd = tmpCwd();
+    onTestFinished(() =>
+      rmSync(cwd, { recursive: true, force: true, maxRetries: 5, retryDelay: 100 }),
+    );
+    const workspace = path.join(cwd, relativePath);
+    const filePath = "apps/web/notes.txt";
+    function git(args: string[]): string {
+      return execFileSync("git", args, { cwd, encoding: "utf8" });
+    }
+    git(["init", "-b", "main"]);
+    git(["config", "user.name", "Test"]);
+    git(["config", "user.email", "test@example.com"]);
+    git(["config", "core.autocrlf", "false"]);
+    mkdirSync(path.join(cwd, "apps", "web"), { recursive: true });
+    writeFileSync(path.join(cwd, filePath), "before\n");
+    writeFileSync(path.join(cwd, "apps/web/untouched.txt"), "unchanged\n");
+    git(["add", "."]);
+    git(["-c", "commit.gpgsign=false", "commit", "-m", "initial"]);
+    git(["checkout", "-b", "feature"]);
+    writeFileSync(path.join(cwd, filePath), "after\n");
+    git(["add", "."]);
+    git(["-c", "commit.gpgsign=false", "commit", "-m", "edit"]);
+    const sha = git(["rev-parse", "HEAD"]).trim();
+
+    const history = await ctx.client.listCheckoutCommits(workspace);
+    const commit = history.commits.find((entry) => entry.sha === sha);
+    expect(commit?.files).toEqual([
+      { path: filePath, additions: 1, deletions: 1, status: "modified" },
+    ]);
+    const result = await ctx.client.getCommitFileDiff(workspace, sha, filePath);
+    expect(result).toEqual({
+      file: {
+        path: filePath,
+        isNew: false,
+        isDeleted: false,
+        additions: 1,
+        deletions: 1,
+        hunks: [
+          {
+            oldStart: 1,
+            oldCount: 1,
+            newStart: 1,
+            newCount: 1,
+            lines: [
+              { type: "header", content: "@@ -1 +1 @@" },
+              { type: "remove", content: "before" },
+              { type: "add", content: "after" },
+            ],
+          },
+        ],
+      },
+    });
+    expect(await ctx.client.getCommitFileDiff(workspace, sha, "apps/web/untouched.txt")).toEqual({
+      file: null,
+    });
+  });
+});
diff --git a/packages/server/src/utils/checkout-git.ts b/packages/server/src/utils/checkout-git.ts
index ee3571504d..caa7e65cb0 100644
--- a/packages/server/src/utils/checkout-git.ts
+++ b/packages/server/src/utils/checkout-git.ts
@@ -2665,10 +2665,11 @@ export async function getCommitFileDiff({
   sha: string;
   path: string;
 }): Promise<ParsedDiffFile | null> {
+  const worktreeRoot = await requireGitWorktreeRoot(cwd);
   const { stdout } = await runGitCommand(
     ["show", sha, "--format=", "--diff-merges=first-parent", ...GIT_PATCH_FORMAT_ARGS, "--", path],
     {
-      cwd,
+      cwd: worktreeRoot,
       envOverlay: READ_ONLY_GIT_ENV,
     },
   );
@@ -2677,9 +2678,9 @@ export async function getCommitFileDiff({
     return null;
   }
 
-  const parsedFiles = await parseAndHighlightDiff(stdout, cwd, {
-    getOldFileContent: (file) => readGitFileContentAtRef(cwd, `${sha}^`, file.path),
-    getNewFileContent: (file) => readGitFileContentAtRef(cwd, sha, file.path),
+  const parsedFiles = await parseAndHighlightDiff(stdout, worktreeRoot, {
+    getOldFileContent: (file) => readGitFileContentAtRef(worktreeRoot, `${sha}^`, file.path),
+    getNewFileContent: (file) => readGitFileContentAtRef(worktreeRoot, sha, file.path),
   });
 
   // `--` scopes the diff to a single pathspec, so there is at most one real