diff --git a/cmd/mesh-controller/main.go b/cmd/mesh-controller/main.go
index 1bc06227..4382d52a 100644
--- a/cmd/mesh-controller/main.go
+++ b/cmd/mesh-controller/main.go
@@ -237,8 +237,8 @@ func run() error {
 	}
 }
 
-func usage() {
-	fmt.Fprint(os.Stderr, `mesh-controller — the control plane
+// usageText is the terminal's help: every command it has, and none it refuses as removed (removedByName).
+var usageText = `mesh-controller — the control plane
 
   On a node the operator types these as 'mesh-cli <command>' (in zsh, 'nox <command>'): asked
   through the node's engine, and run as the controller's terminal only on the control-node
@@ -312,15 +312,14 @@ func usage() {
   operator key make [--out <file>]          make the operator's sealing key, off the mesh; private half to the file only
   operator key set <public> [--replace]     tell the mesh which operator key to seal to
   operator key show                         the operator key, and what it can recover
-  build <repository> [--ref R]   have a build machine build it, and record what came out
-  build --behind                 build every module the mesh holds older than its source
-  build --on <module>            rebuild every module that stands on this module's artifacts, bases first
+  register <module> <owner>/<repository> <path>   register a module from a repository the catalogue does not
+                                 build, from the builder's done key of its fingerprint (ADR 0501 §4)
+  switch [--json]                the switch's list: each module, the build it runs, and what the builder holds
   builds [<module>]              what has been built lately, and what came of it
   queue [--json]                 every ask in the build queue: waiting, in flight (where, how long), dead
   cancel <id>                    drop a waiting or dead ask; recorded failed, cancelled by hand
   clear [--dead]                 cancel every waiting ask (and the dead ones); never one in flight
-  rebuild <module|build-id>      ask the module's source again, or that build's, under a new id
-  replay <build-id> [--register [--older]]   that build's commit again; a dry run unless --register
+  replay <build-id>              that build's commit again, a dry run: what a build of it makes
   kill <id>                      end a build where it runs; recorded failed, killed by hand
   pause [<node>] / resume [<node>]   the build seat's holder there, or every holder, takes nothing new / again
   plans retry <id>               ask a failed plan's failed builds again, and carry the plan on
@@ -355,10 +354,13 @@ func usage() {
   version                        what this binary is
 
 Each context reaches its own store through its own credential (novox/hq ADR 0008), named
-`+store.Variable("<context>")+` — or `+store.FileVariable("<context>")+`, naming a file that holds
+` + store.Variable("<context>") + ` — or ` + store.FileVariable("<context>") + `, naming a file that holds
 the same thing and keeps the password out of the environment. This process holds:
 
-`)
+`
+
+func usage() {
+	fmt.Fprint(os.Stderr, usageText)
 	for _, c := range held {
 		fmt.Fprintf(os.Stderr, "  %-12s database %-12s from %s\n",
 			c.name, store.Database(c.name), store.Variable(c.name))
diff --git a/cmd/mesh-controller/usage_test.go b/cmd/mesh-controller/usage_test.go
new file mode 100644
index 00000000..3dd8a0c9
--- /dev/null
+++ b/cmd/mesh-controller/usage_test.go
@@ -0,0 +1,25 @@
+package main
+
+import (
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// C3 (issue 1851 A11a, A11b, A13; ADR 0501 §4, §5): the terminal's help lists no command it refuses as removed, and lists
+// the ones R4e added: `register` and `switch`.
+func TestTheHelpListsNoRemovedCommandAndTheNewOnes(t *testing.T) {
+	for _, removed := range []string{"build", "rebuild", "forget-checks", "delivery plan"} {
+		if regexp.MustCompile(`(?m)^  `+regexp.QuoteMeta(removed)+` `).MatchString(usageText) {
+			t.Errorf("the help still lists %q, which is refused as removed", removed)
+		}
+	}
+	if strings.Contains(usageText, "--register") {
+		t.Error("the help still lists replay --register, which is refused as removed")
+	}
+	for _, added := range []string{"register <module> <owner>/<repository> <path>", "switch [--json]"} {
+		if !strings.Contains(usageText, "  "+added) {
+			t.Errorf("the help does not list %q", added)
+		}
+	}
+}