fix(cli): allow multiple depends-on args in coder exp sync want (#23869)

Previously the command required exactly two arguments, forcing users to
run it multiple times to declare multiple dependencies for a single
unit.
This accepts variadic depends-on arguments so all dependencies can be
declared in one call:

```
coder exp sync want my-unit dep-1 dep-2 dep-3
```

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Marcin Tojek <mtojek@users.noreply.github.com>

cli/sync_test.go

@@ -165,6 +165,37 @@ func TestSyncCommands_Golden(t *testing.T) {
 		clitest.TestGoldenFile(t, "TestSyncCommands_Golden/want_success", outBuf.Bytes(), nil)
 	})
 
+	t.Run("want_multiple_deps", func(t *testing.T) {
+		t.Parallel()
+		path, cleanup := setupSocketServer(t)
+		defer cleanup()
+
+		ctx := testutil.Context(t, testutil.WaitShort)
+
+		var outBuf bytes.Buffer
+		inv, _ := clitest.New(t, "exp", "sync", "want", "test-unit", "dep-1", "dep-2", "dep-3", "--socket-path", path)
+		inv.Stdout = &outBuf
+		inv.Stderr = &outBuf
+
+		err := inv.WithContext(ctx).Run()
+		require.NoError(t, err)
+
+		// Verify all dependencies were registered by checking status.
+		outBuf.Reset()
+		inv, _ = clitest.New(t, "exp", "sync", "status", "test-unit", "--socket-path", path, "--output", "json")
+		inv.Stdout = &outBuf
+		inv.Stderr = &outBuf
+
+		err = inv.WithContext(ctx).Run()
+		require.NoError(t, err)
+
+		// The output should mention all three dependencies.
+		output := outBuf.String()
+		require.Contains(t, output, "dep-1")
+		require.Contains(t, output, "dep-2")
+		require.Contains(t, output, "dep-3")
+	})
+
 	t.Run("complete", func(t *testing.T) {
 		t.Parallel()
 		path, cleanup := setupSocketServer(t)

cli/sync_want.go

@@ -11,17 +11,16 @@ import (
 
 func (*RootCmd) syncWant(socketPath *string) *serpent.Command {
 	cmd := &serpent.Command{
-		Use:   "want <unit> <depends-on>",
-		Short: "Declare that a unit depends on another unit completing before it can start",
-		Long:  "Declare that a unit depends on another unit completing before it can start. The unit specified first will not start until the second has signaled that it has completed.",
+		Use:   "want <unit> <depends-on> [depends-on...]",
+		Short: "Declare that a unit depends on other units completing before it can start",
+		Long:  "Declare that a unit depends on one or more other units completing before it can start. The unit specified first will not start until all subsequent units have signaled that they have completed.",
 		Handler: func(i *serpent.Invocation) error {
 			ctx := i.Context()
 
-			if len(i.Args) != 2 {
-				return xerrors.New("exactly two arguments are required: unit and depends-on")
+			if len(i.Args) < 2 {
+				return xerrors.New("at least two arguments are required: unit and one or more depends-on")
 			}
 			dependentUnit := unit.ID(i.Args[0])
-			dependsOn := unit.ID(i.Args[1])
 
 			opts := []agentsocket.Option{}
 			if *socketPath != "" {
@@ -34,8 +33,10 @@ func (*RootCmd) syncWant(socketPath *string) *serpent.Command {
 			}
 			defer client.Close()
 
-			if err := client.SyncWant(ctx, dependentUnit, dependsOn); err != nil {
-				return xerrors.Errorf("declare dependency failed: %w", err)
+			for _, dep := range i.Args[1:] {
+				if err := client.SyncWant(ctx, dependentUnit, unit.ID(dep)); err != nil {
+					return xerrors.Errorf("declare dependency failed: %w", err)
+				}
 			}
 
 			cliui.Info(i.Stdout, "Success")

cli/testdata/coder_exp_sync_--help.golden

@@ -16,7 +16,7 @@ SUBCOMMANDS:
     ping        Test agent socket connectivity and health
     start       Wait until all unit dependencies are satisfied
     status      Show unit status and dependency state
-    want        Declare that a unit depends on another unit completing before it
+    want        Declare that a unit depends on other units completing before it
                 can start
 
 OPTIONS:

cli/testdata/coder_exp_sync_want_--help.golden

@@ -1,13 +1,13 @@
 coder v0.0.0-devel
 
 USAGE:
-  coder exp sync want <unit> <depends-on>
+  coder exp sync want <unit> <depends-on> [depends-on...]
 
-  Declare that a unit depends on another unit completing before it can start
+  Declare that a unit depends on other units completing before it can start
 
-  Declare that a unit depends on another unit completing before it can start.
-  The unit specified first will not start until the second has signaled that it
-  has completed.
+  Declare that a unit depends on one or more other units completing before it
+  can start. The unit specified first will not start until all subsequent units
+  have signaled that they have completed.
 
 ———
 Run `coder --help` for a list of global options.