fix(install): treat bun link . the same as bun link

When running `bun link .` in a directory with a package.json, Bun
was failing with "unrecognised dependency format: ." because `.`
was being processed as a package name to link.

Now `bun link .` correctly registers the current package globally,
matching the behavior of `npm link .`.

Fixes #2686

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/cli/link_command.zig

@@ -21,7 +21,11 @@ fn link(ctx: Command.Context) !void {
         Output.flush();
     }
 
-    if (manager.options.positionals.len == 1) {
+    // Treat `bun link .` the same as `bun link` (register current package)
+    const is_register = manager.options.positionals.len == 1 or
+        (manager.options.positionals.len == 2 and std.mem.eql(u8, manager.options.positionals[1], "."));
+
+    if (is_register) {
         // bun link
 
         var lockfile: Lockfile = undefined;

test/regression/issue/2686.test.ts

@@ -0,0 +1,28 @@
+import { spawn } from "bun";
+import { expect, it } from "bun:test";
+import { bunEnv, bunExe, tempDir } from "harness";
+
+// https://github.com/oven-sh/bun/issues/2686
+// `bun link .` should work the same as `bun link` (register the current package globally)
+it("bun link . should register the current package", async () => {
+  using dir = tempDir("bun-link-dot", {
+    "package.json": JSON.stringify({
+      name: "test-link-dot-pkg",
+      version: "1.0.0",
+    }),
+  });
+
+  await using proc = spawn({
+    cmd: [bunExe(), "link", "."],
+    cwd: String(dir),
+    stdout: "pipe",
+    stderr: "pipe",
+    env: bunEnv,
+  });
+
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+
+  expect(stdout).toContain('Success! Registered "test-link-dot-pkg"');
+  expect(stderr).not.toContain("unrecognised dependency format");
+  expect(exitCode).toBe(0);
+});