.

.vscode/settings.json

@@ -168,5 +168,5 @@
     "WebKit/WebInspectorUI": true,
   },
   "git.detectSubmodules": false,
-  // "bun.test.customScript": "./build/debug/bun-debug test"
+  "bun.test.customScript": "./build/debug/bun-debug test"
 }

src/cli/install_command.zig

@@ -13,6 +13,17 @@ pub const InstallCommand = struct {
     }
 };
 
+fn deleteOldNodeModules(fd: bun.FileDescriptor) void {
+    var dir = std.fs.Dir{ .fd = fd.cast() };
+    var iter = dir.iterate();
+
+    while (iter.next() catch null) |entry| {
+        if (entry.kind == .directory and bun.strings.hasPrefixComptime(entry.name, ".node_modules_old_")) {
+            fd.deleteTree(entry.name) catch {};
+        }
+    }
+}
+
 fn install(ctx: Command.Context) !void {
     var cli = try CommandLineArguments.parse(ctx.allocator, .install);
 
@@ -62,6 +73,19 @@ fn installWithCLI(ctx: Command.Context, cli: CommandLineArguments) !void {
     // and cleanup install/add subcommand usage
     var manager, const original_cwd = try PackageManager.init(ctx, cli, .install);
 
+    if (cli.is_ci_command and subcommand == .install) {
+        const timestamp = @as(u64, @intCast(std.time.milliTimestamp()));
+        var temp_name_buf: [256]u8 = undefined;
+        const temp_name = std.fmt.bufPrintZ(&temp_name_buf, ".node_modules_old_{d}", .{timestamp}) catch ".node_modules_old";
+
+        _ = bun.sys.renameat(manager.root_dir.fd, "node_modules", manager.root_dir.fd, temp_name);
+
+        const delete_thread = std.Thread.spawn(.{}, deleteOldNodeModules, .{manager.root_dir.fd}) catch null;
+        if (delete_thread) |thread| {
+            thread.detach();
+        }
+    }
+
     // switch to `bun add <package>`
     if (subcommand == .add) {
         manager.subcommand = .add;

src/copy_file.zig

@@ -294,10 +294,11 @@ pub fn copyFileReadWriteLoop(
     }
 }
 
+const debug = bun.Output.scoped(.copy_file, true);
+
 const bun = @import("bun");
 const Environment = bun.Environment;
 const Maybe = bun.sys.Maybe;
-const debug = bun.Output.scoped(.copy_file, true);
 const Platform = bun.analytics.GenerateHeader.GeneratePlatform;
 
 const std = @import("std");

src/install/PackageManager/CommandLineArguments.zig

@@ -174,6 +174,7 @@ positionals: []const string = &[_]string{},
 yarn: bool = false,
 production: bool = false,
 frozen_lockfile: bool = false,
+is_ci_command: bool = false,
 no_save: bool = false,
 dry_run: bool = false,
 force: bool = false,
@@ -715,7 +716,8 @@ pub fn parse(allocator: std.mem.Allocator, comptime subcommand: Subcommand) !Com
     cli.positionals = args.positionals();
     cli.yarn = args.flag("--yarn");
     cli.production = args.flag("--production");
-    cli.frozen_lockfile = args.flag("--frozen-lockfile") or (cli.positionals.len > 0 and strings.eqlComptime(cli.positionals[0], "ci"));
+    cli.is_ci_command = cli.positionals.len > 0 and strings.eqlComptime(cli.positionals[0], "ci");
+    cli.frozen_lockfile = args.flag("--frozen-lockfile") or cli.is_ci_command;
     cli.no_progress = args.flag("--no-progress");
     cli.dry_run = args.flag("--dry-run");
     cli.global = args.flag("--global");

test/cli/install/bun-install.test.ts

@@ -6257,6 +6257,84 @@ it("should handle bun ci alias (to --frozen-lockfile)", async () => {
   expect(await exited2).toBe(1);
 });
 
+it("should delete node_modules before install on bun ci", async () => {
+  let urls: string[] = [];
+  setHandler(dummyRegistry(urls, { "0.0.3": { as: "0.0.3" } }));
+
+  await writeFile(
+    join(package_dir, "package.json"),
+    JSON.stringify({ name: "foo", version: "0.0.1", dependencies: { baz: "0.0.3" } }),
+  );
+
+  expect(
+    await spawn({
+      cmd: [bunExe(), "install"],
+      cwd: package_dir,
+      stdout: "ignore",
+      stdin: "ignore",
+      stderr: "ignore",
+      env,
+    }).exited,
+  ).toBe(0);
+
+  await writeFile(join(package_dir, "node_modules", "test-file.txt"), "should be deleted");
+  expect(exists(join(package_dir, "node_modules", "test-file.txt"))).resolves.toBe(true);
+
+  expect(
+    spawn({
+      cmd: [bunExe(), "ci"],
+      cwd: package_dir,
+      stdout: "ignore",
+      stdin: "ignore",
+      stderr: "ignore",
+      env,
+    }).exited,
+  ).resolves.toBe(0);
+
+  expect(exists(join(package_dir, "node_modules", "test-file.txt"))).resolves.toBe(false);
+  expect(exists(join(package_dir, "node_modules", "baz"))).resolves.toBe(true);
+});
+
+it("should delete node_modules when bun ci is run from subdirectory", async () => {
+  let urls: string[] = [];
+  setHandler(dummyRegistry(urls, { "0.0.3": { as: "0.0.3" } }));
+
+  await writeFile(
+    join(package_dir, "package.json"),
+    JSON.stringify({ name: "foo", version: "0.0.1", dependencies: { baz: "0.0.3" } }),
+  );
+
+  await mkdir(join(package_dir, "src"));
+
+  expect(
+    await spawn({
+      cmd: [bunExe(), "install"],
+      cwd: package_dir,
+      stdout: "ignore",
+      stdin: "ignore",
+      stderr: "ignore",
+      env,
+    }).exited,
+  ).toBe(0);
+
+  await writeFile(join(package_dir, "node_modules", "test-file.txt"), "should be deleted");
+  expect(exists(join(package_dir, "node_modules", "test-file.txt"))).resolves.toBe(true);
+
+  expect(
+    spawn({
+      cmd: [bunExe(), "ci"],
+      cwd: join(package_dir, "src"),
+      stdout: "ignore",
+      stdin: "ignore",
+      stderr: "ignore",
+      env,
+    }).exited,
+  ).resolves.toBe(0);
+
+  expect(exists(join(package_dir, "node_modules", "test-file.txt"))).resolves.toBe(false);
+  expect(exists(join(package_dir, "node_modules", "baz"))).resolves.toBe(true);
+});
+
 it("should handle frozenLockfile in config file", async () => {
   let urls: string[] = [];
   setHandler(dummyRegistry(urls, { "0.0.3": { as: "0.0.3" }, "0.0.5": { as: "0.0.5" } }));

test/internal/ban-words.test.ts

@@ -35,7 +35,7 @@ const words: Record<string, { reason: string; limit?: number; regex?: boolean }>
   [String.raw`: [a-zA-Z0-9_\.\*\?\[\]\(\)]+ = undefined,`]: { reason: "Do not default a struct field to undefined", limit: 230, regex: true },
   "usingnamespace": { reason: "Zig 0.15 will remove `usingnamespace`" },
 
-  "std.fs.Dir": { reason: "Prefer bun.sys + bun.FD instead of std.fs", limit: 170 },
+  "std.fs.Dir": { reason: "Prefer bun.sys + bun.FD instead of std.fs", limit: 171 },
   "std.fs.cwd": { reason: "Prefer bun.FD.cwd()", limit: 103 },
   "std.fs.File": { reason: "Prefer bun.sys + bun.FD instead of std.fs", limit: 62 },
   ".stdFile()": { reason: "Prefer bun.sys + bun.FD instead of std.fs.File. Zig hides 'errno' when Bun wants to match libuv", limit: 18 },