cli: module issue — deliver a module its scoped broker account (ADR 0048)

'module issue <module> --node <m>' looks up the module's emits/consumes from
the catalogue, ensures the bus exchanges exist, creates its scoped account
(CreateModuleAccount), and seals an amqps {url,fingerprint} to the node as the
module's broker own-secret — the same delivery as 'builder issue', now generic.

Claude-Session: https://claude.ai/code/session_01LrgweAeERJYBg88c5cKDzF

cmd/mesh-control/main.go

@@ -135,6 +135,7 @@ func usage() {
   module list                    what modules this mesh knows about
   module moved <name> <commit>   the source has a newer commit than the mesh built
   module forget <name>           remove one, unless a node is running it
+  module issue <name> --node <m> a broker account for a module, scoped to its emits and consumes
   status [--json]                what is wrong, what is quiet, and what is out of date
   board [--listen ADDR]          the same three questions, as a page that holds nothing
   api --issuer URL [--listen A]  assign and unassign over http, for a surface that is not here

cmd/mesh-control/modules.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"context"
+	"crypto/rand"
+	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"flag"
@@ -10,6 +12,7 @@ import (
 	"sort"
 	"strings"
 
+	"github.com/novox/mesh-control/internal/broker"
 	"github.com/novox/mesh-control/internal/catalogue"
 	"github.com/novox/mesh-control/internal/inventory"
 	"github.com/novox/mesh-control/internal/overlay"
@@ -194,8 +197,80 @@ func moduleCommand(ctx context.Context, args []string) error {
 		fmt.Printf("%s forgotten\n", args[1])
 		return nil
 
+	case "issue":
+		// A module's broker account, scoped by its emits and consumes (novox/hq ADR 0048) and
+		// sealed to the machine that will run it — the generic case the builder was the first of.
+		set := flag.NewFlagSet("module issue", flag.ContinueOnError)
+		forNode := set.String("node", "",
+			"the machine that will run it, so the credential is delivered instead of printed")
+		positionals, err := parseAround(set, args[1:])
+		if err != nil {
+			return err
+		}
+		if len(positionals) != 1 {
+			return errors.New("module issue <module> --node <machine>")
+		}
+		module := positionals[0]
+		if *forNode == "" {
+			return errors.New("module issue needs --node: a module's account is sealed to the " +
+				"machine that runs it, and the mesh cannot read it back to print")
+		}
+
+		shelf, err := inv.Catalogue(ctx)
+		if err != nil {
+			return err
+		}
+		m, ok := shelf[module]
+		if !ok {
+			return fmt.Errorf("this mesh knows no module %q; `module add` it first", module)
+		}
+
+		management, err := broker.ManagementFromEnvironment()
+		if err != nil {
+			return err
+		}
+		// The substrate owns the bus; make sure it exists before a module binds onto it.
+		if err := management.EnsureEventExchanges(ctx); err != nil {
+			return err
+		}
+
+		secret := make([]byte, 32)
+		if _, err := rand.Read(secret); err != nil {
+			return err
+		}
+		password := base64.RawURLEncoding.EncodeToString(secret)
+		account, err := management.CreateModuleAccount(ctx, *forNode, module, password, m.Emits, m.Consumes)
+		if err != nil {
+			return err
+		}
+
+		known, err := broker.FromEnvironment()
+		if err != nil {
+			return fmt.Errorf("cannot deliver a credential without knowing where the broker is: %w", err)
+		}
+		// The URL and what verifies the broker, together — a mesh's broker presents its own
+		// certificate, in no public trust store, so a URL alone fails at TLS (as `builder issue`).
+		held, err := json.Marshal(struct {
+			URL         string `json:"url"`
+			Fingerprint string `json:"fingerprint,omitempty"`
+		}{
+			URL:         fmt.Sprintf("amqps://%s:%s@%s/", account, password, known.Address),
+			Fingerprint: known.Fingerprint,
+		})
+		if err != nil {
+			return err
+		}
+		if err := inv.AcceptSecretForModule(ctx, *forNode, module, "broker", string(held)); err != nil {
+			return err
+		}
+		fmt.Printf("broker account %s created for %s, scoped to what it emits and consumes\n",
+			account, module)
+		fmt.Printf("  sealed to %s. It arrives with the next push — `push %s` to send it\n",
+			*forNode, *forNode)
+		return nil
+
 	default:
-		return fmt.Errorf("module has no %q; it has add, list, moved and forget", args[0])
+		return fmt.Errorf("module has no %q; it has add, list, moved, forget and issue", args[0])
 	}
 }