feat: add mcpd config volumes remove command

Implement `mcpd config volumes remove <server-name> -- --<volume-name>`
to remove volume mappings from MCP server runtime configurations.

Also improves the existing `set` command: noop-aware messaging,
consistent validation naming, and clearer withVolumes doc comment.

Closes #200

Author: peteski22

cmd/config/volumes/cmd.go

@@ -1,10 +1,13 @@
 package volumes
 
 import (
+	"maps"
+
 	"github.com/spf13/cobra"
 
 	"github.com/mozilla-ai/mcpd/internal/cmd"
 	cmdopts "github.com/mozilla-ai/mcpd/internal/cmd/options"
+	"github.com/mozilla-ai/mcpd/internal/context"
 )
 
 // NewCmd creates a new volumes command with its sub-commands.
@@ -18,8 +21,9 @@ func NewCmd(baseCmd *cmd.BaseCmd, opt ...cmdopts.CmdOption) (*cobra.Command, err
 
 	// Sub-commands for: mcpd config volumes
 	fns := []func(baseCmd *cmd.BaseCmd, opt ...cmdopts.CmdOption) (*cobra.Command, error){
-		NewListCmd, // list
-		NewSetCmd,  // set
+		NewListCmd,   // list
+		NewRemoveCmd, // remove
+		NewSetCmd,    // set
 	}
 
 	for _, fn := range fns {
@@ -32,3 +36,16 @@ func NewCmd(baseCmd *cmd.BaseCmd, opt ...cmdopts.CmdOption) (*cobra.Command, err
 
 	return cobraCmd, nil
 }
+
+// withVolumes returns a new ServerExecutionContext with both volume fields
+// set to unexpanded values. Volumes (the TOML-serialized field) preserves
+// env var references on disk. RawVolumes is kept in sync for Equals/IsEmpty
+// comparisons during Upsert.
+func withVolumes(
+	server context.ServerExecutionContext,
+	working context.VolumeExecutionContext,
+) context.ServerExecutionContext {
+	server.RawVolumes = maps.Clone(working)
+	server.Volumes = maps.Clone(working)
+	return server
+}

cmd/config/volumes/remove.go

@@ -0,0 +1,160 @@
+package volumes
+
+import (
+	"fmt"
+	"maps"
+	"slices"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"github.com/mozilla-ai/mcpd/internal/cmd"
+	cmdopts "github.com/mozilla-ai/mcpd/internal/cmd/options"
+	"github.com/mozilla-ai/mcpd/internal/context"
+	"github.com/mozilla-ai/mcpd/internal/flags"
+)
+
+// removeCmd handles removing volume mappings from MCP servers.
+type removeCmd struct {
+	*cmd.BaseCmd
+	ctxLoader context.Loader
+}
+
+// NewRemoveCmd creates a new remove command for volume configuration.
+func NewRemoveCmd(baseCmd *cmd.BaseCmd, opt ...cmdopts.CmdOption) (*cobra.Command, error) {
+	opts, err := cmdopts.NewOptions(opt...)
+	if err != nil {
+		return nil, err
+	}
+
+	c := &removeCmd{
+		BaseCmd:   baseCmd,
+		ctxLoader: opts.ContextLoader,
+	}
+
+	cobraCmd := &cobra.Command{
+		Use:   "remove <server-name> -- --<volume-name> [--<volume-name>...]",
+		Short: "Remove volume mappings from an MCP server",
+		Long: "Remove volume mappings from an MCP server in the runtime context " +
+			"configuration file (e.g. " + flags.RuntimeFile + ").\n\n" +
+			"Use -- to separate the server name from the volume names to remove.\n\n" +
+			"Examples:\n" +
+			"  # Remove a single volume mapping\n" +
+			"  mcpd config volumes remove filesystem -- --workspace\n\n" +
+			"  # Remove multiple volume mappings\n" +
+			"  mcpd config volumes remove filesystem -- --workspace --gdrive",
+		RunE: c.run,
+		Args: validateRemoveArgs,
+	}
+
+	return cobraCmd, nil
+}
+
+// validateRemoveArgs validates the arguments for the remove command.
+// It wraps validateRemoveArgsCore to extract the dash position from the cobra command.
+func validateRemoveArgs(cmd *cobra.Command, args []string) error {
+	return validateRemoveArgsCore(cmd.ArgsLenAtDash(), args)
+}
+
+// validateRemoveArgsCore validates the remove command arguments given the dash position and args slice.
+func validateRemoveArgsCore(dashPos int, args []string) error {
+	if len(args) == 0 {
+		return fmt.Errorf("server-name is required")
+	}
+	if dashPos == -1 {
+		return fmt.Errorf(
+			"missing '--' separator: usage: mcpd config volumes remove <server-name> -- --<volume-name>",
+		)
+	}
+	// -- at position 0 means no server name before it.
+	if dashPos < 1 {
+		return fmt.Errorf("server-name is required")
+	}
+	if strings.TrimSpace(args[0]) == "" {
+		return fmt.Errorf("server-name is required")
+	}
+	if dashPos > 1 {
+		return fmt.Errorf("too many arguments before --")
+	}
+	if len(args) < 2 {
+		return fmt.Errorf("volume name(s) required after --")
+	}
+	return nil
+}
+
+// run executes the remove command, deleting volume mappings from the server config.
+func (c *removeCmd) run(cobraCmd *cobra.Command, args []string) error {
+	serverName := strings.TrimSpace(args[0])
+
+	// volumeArgs contains everything after the -- separator.
+	// validateRemoveArgs guarantees len(args) >= 2.
+	volumeArgs := args[1:]
+	volumeNames, err := parseRemoveArgs(volumeArgs)
+	if err != nil {
+		return err
+	}
+
+	cfg, err := c.ctxLoader.Load(flags.RuntimeFile)
+	if err != nil {
+		return fmt.Errorf("failed to load execution context config: %w", err)
+	}
+
+	// Get returns a value copy; safe to modify.
+	server, ok := cfg.Get(serverName)
+	if !ok {
+		return fmt.Errorf("server '%s' not found in configuration", serverName)
+	}
+
+	working := maps.Clone(server.RawVolumes)
+	if working == nil {
+		working = context.VolumeExecutionContext{}
+	}
+	for _, name := range volumeNames {
+		delete(working, name)
+	}
+	server = withVolumes(server, working)
+
+	res, err := cfg.Upsert(server)
+	if err != nil {
+		return fmt.Errorf("error removing volumes for server '%s': %w", serverName, err)
+	}
+
+	sorted := slices.Clone(volumeNames)
+	slices.Sort(sorted)
+
+	out := cobraCmd.OutOrStdout()
+
+	var msg string
+	switch res {
+	case context.Noop:
+		msg = fmt.Sprintf("No changes — specified volumes not present on server '%s': %v", serverName, sorted)
+	default:
+		msg = fmt.Sprintf("✓ Volumes removed for server '%s' (operation: %s): %v", serverName, string(res), sorted)
+	}
+
+	if _, err := fmt.Fprintln(out, msg); err != nil {
+		return fmt.Errorf("failed to write output: %w", err)
+	}
+
+	return nil
+}
+
+// parseRemoveArgs parses volume name arguments in the format --name.
+func parseRemoveArgs(args []string) ([]string, error) {
+	names := make([]string, 0, len(args))
+
+	for _, arg := range args {
+		if !strings.HasPrefix(arg, "--") {
+			return nil, fmt.Errorf("invalid volume name '%s': must start with --", arg)
+		}
+
+		name := strings.TrimSpace(strings.TrimPrefix(arg, "--"))
+		if name == "" {
+			return nil, fmt.Errorf("volume name cannot be empty in '%s'", arg)
+		}
+
+		names = append(names, name)
+	}
+
+	return names, nil
+}