The control plane's own manifest says where the node put the store and the broker

Beside each sealed connection genesis wrote, the port this machine put the
seat's holder at: `${seat:mesh-store:5432}` for the three stores,
`${seat:mesh-broker:…}` for the bus, the plain AMQP port and the management API.
Filled from the node's settings when the control plane composes its own
declaration; empty — the sealed value stands — when the mesh has nothing to add.

On its own, after the commit before it is built and running: a control plane
that does not know the placeholder passes it through as the value, and this
manifest is composed by whatever control plane is running when it is pushed.
The reader ignores an unfilled placeholder either way, and a test holds it to
ignoring exactly what this manifest says.

novox/hq 04-ISSUES/102

cmd/mesh-controller/addresses_test.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/novox/mesh-controller/internal/catalogue"
 	"github.com/novox/mesh-controller/internal/inventory"
+	"github.com/novox/mesh-controller/internal/licences"
 	"github.com/novox/mesh-controller/internal/link"
 )
 
@@ -153,7 +154,7 @@ func TestTheControlPlaneIsToldWhereTheNodePutTheStoreAndTheBroker(t *testing.T)
 	if err != nil {
 		t.Fatal(err)
 	}
-	control, err := m.Resolve([]catalogue.Built{{Name: "server", Kind: catalogue.ArtifactImage,
+	control, err := withSeatPorts(m).Resolve([]catalogue.Built{{Name: "server", Kind: catalogue.ArtifactImage,
 		Reference: "registry.example/control@" + aDigest}})
 	if err != nil {
 		t.Fatal(err)
@@ -198,15 +199,137 @@ func TestTheControlPlaneIsToldWhereTheNodePutTheStoreAndTheBroker(t *testing.T)
 		t.Fatal("the control plane's container is not in its own node's declaration")
 	}
 	for key, want := range map[string]string{
-		"MESH_STORE_INVENTORY_PORT":   "6852",
-		"MESH_STORE_IDENTITY_PORT":    "6852",
-		"MESH_STORE_LICENCES_PORT":    "6852",
-		"MESH_BROKER_AMQP_PORT":       "5679",
-		"MESH_BROKER_ADDRESS_PORT":    "5671",
-		"MESH_BROKER_MANAGEMENT_PORT": "15672",
+		"MESH_STORE_INVENTORY_PORT": "6852",
+		"MESH_STORE_IDENTITY_PORT":  "6852",
+		"MESH_STORE_LICENCES_PORT":  "6852",
+		"MESH_BROKER_AMQP_PORT":     "5679",
+		// Neither given nor assigned by the mesh: the manifest's own number is NOT the answer,
+		// because the sealed value beside it carries the port genesis wrote (finding F3).
+		"MESH_BROKER_ADDRESS_PORT":    "",
+		"MESH_BROKER_MANAGEMENT_PORT": "",
 	} {
 		if env[key] != want {
 			t.Errorf("the control plane is told %s=%v; the node says %q", key, env[key], want)
 		}
 	}
 }
+
+// withSeatPorts is the control plane's manifest with the seat placeholders in its environment —
+// added here until module.json carries them (the manifest lands one commit after the code that
+// fills it, so a control plane one build behind never sees a placeholder it cannot fill).
+func withSeatPorts(m catalogue.Manifest) catalogue.Manifest {
+	seatPorts := map[string]string{
+		"MESH_STORE_INVENTORY_PORT":   "${seat:mesh-store:5432}",
+		"MESH_STORE_IDENTITY_PORT":    "${seat:mesh-store:5432}",
+		"MESH_STORE_LICENCES_PORT":    "${seat:mesh-store:5432}",
+		"MESH_BROKER_AMQP_PORT":       "${seat:mesh-broker:5672}",
+		"MESH_BROKER_MANAGEMENT_PORT": "${seat:mesh-broker:15672}",
+		"MESH_BROKER_ADDRESS_PORT":    "${seat:mesh-broker:5671}",
+	}
+	out := m
+	out.Resources = nil
+	for _, r := range m.Resources {
+		if r["type"] != "container" {
+			out.Resources = append(out.Resources, r)
+			continue
+		}
+		copied := map[string]any{}
+		for k, v := range r {
+			copied[k] = v
+		}
+		env := map[string]any{}
+		if had, ok := r["env"].(map[string]any); ok {
+			for k, v := range had {
+				env[k] = v
+			}
+		}
+		for k, v := range seatPorts {
+			if _, said := env[k]; !said {
+				env[k] = v
+			}
+		}
+		copied["env"] = env
+		out.Resources = append(out.Resources, copied)
+	}
+	return out
+}
+
+// aLoneNode is one capable machine with nothing placed on any network — the control-node during
+// genesis, before the "network" step, which is after the store, the broker, the vault and the
+// catalogue have each been built and pushed (finding F2).
+func aLoneNode(t *testing.T) *stores {
+	t.Helper()
+	inventory.ForTest(t)
+	licences.ForTest(t)
+	open, err := openStores(t.Context())
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(open.Close)
+	for _, m := range provided {
+		if err := open.inventory.Provide(t.Context(), m); err != nil {
+			t.Fatal(err)
+		}
+	}
+	record, err := open.inventory.AddNode(t.Context(), "anchor")
+	if err != nil {
+		t.Fatal(err)
+	}
+	reported, _ := json.Marshal(map[string]any{"capabilities": []map[string]any{
+		{"name": "container-runtime", "present": true}}})
+	var profile map[string]any
+	_ = json.Unmarshal(reported, &profile)
+	if err := open.inventory.RecordProfile(t.Context(), record.ID, profile); err != nil {
+		t.Fatal(err)
+	}
+	if err := open.inventory.RecordSealingKey(t.Context(), record.ID, aPublicKey(t)); err != nil {
+		t.Fatal(err)
+	}
+	return open
+}
+
+// **Before the network exists, the store's own node reaches it by loopback** — never refused,
+// never handed the scheme: a genesis pushes the store, the broker, the vault and the catalogue to
+// a node on no network, and builds the catalogue on a base it must be able to pull.
+func TestOnANodeWithNoNetworkTheStoreIsReachedByLoopback(t *testing.T) {
+	open := aLoneNode(t)
+	ctx := t.Context()
+	register(t, open, aStore())
+	register(t, open, catalogue.Manifest{Module: "builder", Version: "1",
+		Requires: []string{catalogue.ArtifactStoreProvision},
+		Resources: []map[string]any{{"id": "server", "type": "container", "name": "mesh-builder",
+			"image": "registry.example/mesh-builder@" + aDigest}}})
+	if err := open.inventory.RecordBuild(ctx, inventory.Build{
+		ID: "b1", Repository: "r", Module: "postgres", Commit: "abc",
+		Made: []inventory.Artifact{{Name: "runtime", Kind: "image",
+			Reference: catalogue.ArtifactStoreScheme + "postgres/runtime@" + aDigest}},
+	}); err != nil {
+		t.Fatal(err)
+	}
+	register(t, open, catalogue.Manifest{Module: "postgres", Version: "1",
+		Resources: []map[string]any{{"id": "runtime", "type": "container", "name": "mesh-postgres",
+			"image": catalogue.ArtifactStoreScheme + "postgres/runtime@" + aDigest}}})
+	for _, module := range []string{"distribution", "builder", "postgres"} {
+		if _, err := assign(ctx, open, "anchor", module); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := open.inventory.SetSettings(ctx, "anchor", "distribution",
+		map[string]any{catalogue.PortsSetting: map[string]any{"5000": 5100}}); err != nil {
+		t.Fatal(err)
+	}
+
+	var image any
+	for _, r := range composed(t, open, "anchor").Resources {
+		if r["id"] == "postgres.runtime" {
+			image = r["image"]
+		}
+	}
+	if image != "127.0.0.1:5100/postgres/runtime@"+aDigest {
+		t.Fatalf("on the store's own node, off any network, the image is fetched as %v", image)
+	}
+	held := heldBy(ctx)
+	if got := held["postgres/runtime"]; got != "127.0.0.1:5100/postgres/runtime@"+aDigest {
+		t.Fatalf("a builder beside the store is handed the base %q", got)
+	}
+}

cmd/mesh-controller/build.go

@@ -510,7 +510,7 @@ func heldBy(ctx context.Context) map[string]string {
 		fmt.Fprintf(os.Stderr, "could not read what this mesh has built: %v\n", err)
 		return nil
 	}
-	address, err := whereTheStoreIs(ctx, open.inventory)
+	address, err := whereABuilderReachesTheStore(ctx, open.inventory)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "could not find the artifact store on this mesh's network, so a "+
 			"module naming a base will be handed a reference nothing can fetch: %v\n", err)

cmd/mesh-controller/network.go

@@ -494,11 +494,18 @@ func artifactStoreOnNetwork(ctx context.Context, inv *inventory.Inventory,
 	return "", "", false, nil
 }
 
-// artifactStoreAddress is the artifact store as this network reaches it, `<node>.internal:<port>`,
-// or "" when the mesh has none on its network yet — the address composed into every reference
-// the mesh built, at the moment it is used and never before (novox/hq 04-ISSUES/102).
+// artifactStoreAddress is the artifact store as `forNode` reaches it: `<node>.internal:<port>`
+// over the private network, or — when nothing is on the network yet — `127.0.0.1:<port>` for the
+// node that holds the store itself, and "" for any other. The address composed into every
+// reference the mesh built, at the moment it is used and never before (novox/hq 04-ISSUES/102).
+//
+// **Genesis places the network after the store, the broker, the vault and the catalogue.** Each
+// of those is built and pushed to a node that is on no network, and the store is on that same
+// node; an answer of "no store" there would refuse every one of those pushes and hand every one
+// of those builds a base nothing can pull. Loopback is the truth on that machine, and it is the
+// address genesis itself reaches the store by.
 func artifactStoreAddress(ctx context.Context, inv *inventory.Inventory,
-	shelf map[string]catalogue.Manifest) (string, error) {
+	shelf map[string]catalogue.Manifest, forNode string) (string, error) {
 	onNetwork, err := whereEveryoneIs(ctx, inv, shelf)
 	if err != nil {
 		return "", err
@@ -508,8 +515,29 @@ func artifactStoreAddress(ctx context.Context, inv *inventory.Inventory,
 		on[name] = true
 	}
 	node, port, found, err := artifactStoreOnNetwork(ctx, inv, on)
-	if err != nil || !found {
+	if err != nil {
 		return "", err
 	}
-	return overlay.InternalName(node) + ":" + port, nil
+	if found {
+		return overlay.InternalName(node) + ":" + port, nil
+	}
+	holder, port, found, err := artifactStoreHolder(ctx, inv)
+	if err != nil || !found || holder != forNode {
+		return "", err
+	}
+	return "127.0.0.1:" + port, nil
+}
+
+// artifactStoreHolder is whichever node is assigned a module offering the artifact store, on or
+// off the network, and the port that node put it on.
+func artifactStoreHolder(ctx context.Context, inv *inventory.Inventory) (node, port string, found bool, err error) {
+	nodes, err := inv.Nodes(ctx)
+	if err != nil {
+		return "", "", false, err
+	}
+	all := map[string]bool{}
+	for _, n := range nodes {
+		all[n.Name] = true
+	}
+	return artifactStoreOnNetwork(ctx, inv, all)
 }

cmd/mesh-controller/plan.go

@@ -481,17 +481,10 @@ func renderingFor(ctx context.Context, open *stores, node string,
 		return catalogue.Rendering{}, inventory.Node{}, err
 	}
 
-	// Where this node put the foundation's servers, for the control plane's own connections
-	// (novox/hq 04-ISSUES/102): read from the node's settings for whatever claims each seat,
-	// exactly as a consumer's binding is, never from what genesis wrote into a secret.
-	seats, err := seatsOn(ctx, inv, shelf, node, plan.Modules)
-	if err != nil {
-		return catalogue.Rendering{}, inventory.Node{}, err
-	}
-	// And the artifact store as this network reaches it now — the address every image and
-	// archive the mesh built is fetched through, composed here and recorded nowhere — with what
-	// the mesh has built, so a reference recorded with an address before that is re-routed too.
-	artifactStore, err := artifactStoreAddress(ctx, inv, shelf)
+	// The artifact store as this node reaches it now — the address every image and archive the
+	// mesh built is fetched through, composed here and recorded nowhere — with what the mesh has
+	// built, so a reference recorded with an address before that is re-routed too.
+	artifactStore, err := artifactStoreAddress(ctx, inv, shelf, node)
 	if err != nil {
 		return catalogue.Rendering{}, inventory.Node{}, err
 	}
@@ -571,6 +564,13 @@ func renderingFor(ctx context.Context, open *stores, node string,
 			taken[m] = true
 		}
 	}
+	// Where this node put the foundation's servers, for the control plane's own connections
+	// (novox/hq 04-ISSUES/102): read from the node's settings for whatever claims each seat,
+	// exactly as a consumer's binding is, never from what genesis wrote into a secret.
+	seats, err := seatsOn(ctx, inv, shelf, node, plan.Modules, record.Adopted, taken)
+	if err != nil {
+		return catalogue.Rendering{}, inventory.Node{}, err
+	}
 	return catalogue.Rendering{
 		Settings: settings, Generators: gens, Grants: grants, Needed: needed, Ports: ports,
 		Certificate: certificate, Authority: authority, Mesh: private, Names: names,
@@ -1023,7 +1023,7 @@ func portsGivenOn(ctx context.Context, inv *inventory.Inventory, node string,
 // and not yet assigned (04-ISSUES/085), and the control plane must follow that setting from the
 // first declaration it composes for itself. A holder in this node's set wins over one that is not.
 func seatsOn(ctx context.Context, inv *inventory.Inventory, shelf map[string]catalogue.Manifest,
-	node string, inSet []catalogue.Manifest) (map[string]map[int]int, error) {
+	node string, inSet []catalogue.Manifest, adopted bool, taken map[string]bool) (map[string]map[int]int, error) {
 	assigned := map[string]bool{}
 	for _, m := range inSet {
 		assigned[m.Module] = true
@@ -1045,26 +1045,26 @@ func seatsOn(ctx context.Context, inv *inventory.Inventory, shelf map[string]cat
 		if len(claims) == 0 {
 			continue
 		}
+		// **Only a port the node was given or the mesh assigned — never the manifest's own
+		// number.** The sealed value the answer sits beside carries the port genesis wrote, which
+		// on a given-port node is the predecessor's; a manifest's long-form mapping is the
+		// catalogue's default, and answering with it would override the right number with one
+		// the mesh never checked (the contract in seat_into.go). And on an adopted node a holder
+		// assigned but not yet taken is the found container, on the ports it was found with, not
+		// the declaration's — so its mesh-assigned ports do not count there either; a given port
+		// does, because a given port is the found one by construction (ADR 0100).
 		ports, _, err := portsGivenOn(ctx, inv, node, m)
 		if err != nil {
 			return nil, err
 		}
-		if assigned[name] {
-			// Running here, so what its manifest publishes the long way is where this machine
-			// has it — the same reading the declaration itself makes (ADR 0038). Only for a
-			// holder in this node's set: a manifest's number says nothing about a machine the
-			// module does not run on.
-			var declared []int
-			for _, l := range m.Listens {
-				declared = append(declared, l.Port)
+		if adopted && !taken[name] {
+			layers, err := inv.SettingsFor(ctx, node, m.Module)
+			if err != nil {
+				return nil, err
 			}
-			for _, wanted := range append(declared, m.Guards...) {
-				if _, said := ports[wanted]; said {
-					continue
-				}
-				if at, mayAssign := m.MachineSide(wanted); !mayAssign && at != 0 {
-					ports[wanted] = at
-				}
+			ports = map[int]int{}
+			if given, err := catalogue.GivenPorts(m, layers); err == nil {
+				ports = given
 			}
 		}
 		if len(ports) == 0 {

cmd/mesh-controller/references.go

@@ -101,12 +101,50 @@ func routedArtifacts(made []inventory.Artifact, address string) []inventory.Arti
 	return out
 }
 
-// whereTheStoreIs is the artifact store's address as this network reaches it, or "" — read for a
-// caller that has the inventory open and nothing else in hand.
-func whereTheStoreIs(ctx context.Context, inv *inventory.Inventory) (string, error) {
+// whereTheStoreIs is the artifact store's address as something on `forNode` reaches it, or "" —
+// read for a caller that has the inventory open and nothing else in hand. With no node named, the
+// store's own node: loopback when nothing is on the network yet.
+func whereTheStoreIs(ctx context.Context, inv *inventory.Inventory, forNode string) (string, error) {
 	shelf, err := inv.Catalogue(ctx)
 	if err != nil {
 		return "", err
 	}
-	return artifactStoreAddress(ctx, inv, shelf)
+	if forNode == "" {
+		if holder, _, found, err := artifactStoreHolder(ctx, inv); err != nil {
+			return "", err
+		} else if found {
+			forNode = holder
+		}
+	}
+	return artifactStoreAddress(ctx, inv, shelf, forNode)
+}
+
+// whereABuilderReachesTheStore is the store's address for the machine that builds: the network's
+// when there is one, else loopback on the store's own node — when that node also holds a module
+// requiring the store, which is what a builder is (genesis: one node holds both).
+func whereABuilderReachesTheStore(ctx context.Context, inv *inventory.Inventory) (string, error) {
+	shelf, err := inv.Catalogue(ctx)
+	if err != nil {
+		return "", err
+	}
+	holder, _, found, err := artifactStoreHolder(ctx, inv)
+	if err != nil || !found {
+		return "", err
+	}
+	assigned, err := inv.Assigned(ctx, holder)
+	if err != nil {
+		return "", err
+	}
+	besideIt := false
+	for _, a := range assigned {
+		for _, r := range shelf[a].Requires {
+			if r == catalogue.ArtifactStoreProvision {
+				besideIt = true
+			}
+		}
+	}
+	if !besideIt {
+		holder = ""
+	}
+	return artifactStoreAddress(ctx, inv, shelf, holder)
 }

cmd/mesh-controller/upgrades.go

@@ -184,7 +184,7 @@ func (f following) Announceable(ctx context.Context) ([]link.Announcement, error
 	if err != nil {
 		return nil, err
 	}
-	address, err := whereTheStoreIs(ctx, f.open.inventory)
+	address, err := whereTheStoreIs(ctx, f.open.inventory, "")
 	if err != nil {
 		return nil, err
 	}

internal/catalogue/artifacts.go

@@ -97,6 +97,15 @@ func Rerouted(reference, address string) string {
 //
 // A kept reference with no store to route it through is refused: sent as it is, the runtime would
 // refuse the scheme on the machine, one push away from the reason.
+//
+// **What this does not reach: the images genesis pinned.** The installer builds the control plane
+// and the builder before the mesh exists, pushes them itself and pins their manifests to
+// `<registry>:<port>/mesh-controller@…` and `<registry>:<port>/mesh-builder@…` — single-segment
+// repositories with no build record, so `with.Built` does not name them and they are left as
+// written until each is rebuilt through the mesh, which records it by digest and path. Until then
+// a registry that moves strands exactly those two on a recreate, and the control plane's is the
+// one that cannot be repaired through the mesh. Rebuild both through `build` before moving the
+// store (novox/hq 04-ISSUES/102, finding F4).
 func artifactsInto(resource map[string]any, module string, with Rendering) error {
 	for _, key := range []string{"image", "source"} {
 		written, ok := resource[key].(string)

internal/catalogue/seat_into_test.go

@@ -101,6 +101,19 @@ func TestTheControlPlanesOwnAddressesFollowTheNodesPorts(t *testing.T) {
 	if err != nil {
 		t.Fatalf("the control plane's own manifest does not parse:\n%v", err)
 	}
+	// The manifest itself names them now; withSeatPorts is a no-op on it, and this holds it so.
+	for _, r := range m.Resources {
+		if r["type"] != "container" {
+			continue
+		}
+		env, _ := r["env"].(map[string]any)
+		for key, want := range SeatPorts {
+			if env[key] != want {
+				t.Errorf("module.json says %s=%v, not %q", key, env[key], want)
+			}
+		}
+	}
+	m = withSeatPorts(m)
 	control, err := m.Resolve([]Built{{
 		Name: "server", Kind: ArtifactImage,
 		Reference: ArtifactStoreScheme + "mesh-controller/server@sha256:" + strings.Repeat("c", 64),
@@ -155,3 +168,49 @@ func TestTheControlPlanesOwnAddressesFollowTheNodesPorts(t *testing.T) {
 		t.Errorf("with no settings, the control plane is told %v", env)
 	}
 }
+
+// SeatPorts is what the control plane's manifest says beside each sealed connection: the port
+// this machine put the seat's holder at (novox/hq 04-ISSUES/102).
+var SeatPorts = map[string]string{
+	"MESH_STORE_INVENTORY_PORT":   "${seat:mesh-store:5432}",
+	"MESH_STORE_IDENTITY_PORT":    "${seat:mesh-store:5432}",
+	"MESH_STORE_LICENCES_PORT":    "${seat:mesh-store:5432}",
+	"MESH_BROKER_AMQP_PORT":       "${seat:mesh-broker:5672}",
+	"MESH_BROKER_MANAGEMENT_PORT": "${seat:mesh-broker:15672}",
+	"MESH_BROKER_ADDRESS_PORT":    "${seat:mesh-broker:5671}",
+}
+
+// withSeatPorts is the control plane's manifest with SeatPorts in its container's environment.
+//
+// **The manifest lands one commit after the code that fills it**, deliberately: a control plane
+// still running the previous build passes `${seat:…}` through unfilled, and the manifest may only
+// name the placeholder once every control plane that could compose it knows it. So the test does
+// not depend on module.json carrying these yet, and is a no-op once it does.
+func withSeatPorts(m Manifest) Manifest {
+	out := m
+	out.Resources = nil
+	for _, r := range m.Resources {
+		if r["type"] != "container" {
+			out.Resources = append(out.Resources, r)
+			continue
+		}
+		copied := map[string]any{}
+		for k, v := range r {
+			copied[k] = v
+		}
+		env := map[string]any{}
+		if had, ok := r["env"].(map[string]any); ok {
+			for k, v := range had {
+				env[k] = v
+			}
+		}
+		for k, v := range SeatPorts {
+			if _, said := env[k]; !said {
+				env[k] = v
+			}
+		}
+		copied["env"] = env
+		out.Resources = append(out.Resources, copied)
+	}
+	return out
+}

internal/envfile/port.go

@@ -40,6 +40,20 @@ func Port(name string) (string, error) {
 	if raw == "" {
 		return "", nil
 	}
+	if unfilled.MatchString(raw) {
+		// **A placeholder the mesh never filled, and this is the one place it must not be a
+		// fault.** The control plane composes its own declaration, so a manifest naming
+		// `${seat:…}` reaches a control plane one build older than the manifest — one that does
+		// not know the placeholder and passes it through as the value. Refusing it here would
+		// leave every command and the daemon unable to open a store: headless, on the machine
+		// that cannot be repaired through the mesh (novox/hq 04-ISSUES/102). So it is what an
+		// empty answer is — nothing said, the sealed value stands — and it is said aloud, because
+		// a manifest ahead of its binary is worth a line on stderr and not worth an outage.
+		fmt.Fprintf(os.Stderr, "%s is %q, a placeholder nothing filled in — ignored; the port in "+
+			"%s stands. The control plane composing this declaration is older than the manifest "+
+			"naming it: rebuild and push it\n", PortVar(name), raw, name)
+		return "", nil
+	}
 	n, err := strconv.Atoi(raw)
 	if err != nil || n < 1 || n > 65535 {
 		return "", fmt.Errorf("%s is %q, which is not a port", PortVar(name), raw)
@@ -70,6 +84,10 @@ func Placed(name string) (string, error) {
 // keywordPort is `port=…` in a `key=value` connection string.
 var keywordPort = regexp.MustCompile(`(^|\s)port=\S*`)
 
+// unfilled is a value that is still a placeholder — `${…}` — rather than something a person or the
+// mesh wrote as a port.
+var unfilled = regexp.MustCompile(`^\$\{[^}]*\}$`)
+
 // WithPort is the value with its port replaced by `port`.
 //
 // Three shapes, because the control plane's settings come in three: a URL
@@ -84,14 +102,19 @@ func WithPort(value, port string) (string, error) {
 		return "", fmt.Errorf("the value is empty")
 	}
 	if scheme, rest, isURL := strings.Cut(value, "://"); isURL {
-		end := strings.IndexAny(rest, "/?#")
-		authority, tail := rest, ""
-		if end >= 0 {
-			authority, tail = rest[:end], rest[end:]
+		// **The password may hold any of `/ ? # @`, so the host begins after the LAST `@`**, and
+		// the path only after that. Cutting at the first `/` would take a password's slash for the
+		// path's and put the new port on the user name — a connection string that dials the wrong
+		// host without a word. Genesis makes passwords that cannot do this; an accepted one can.
+		// The connection strings this reads — a store's, a broker's, a management API's — carry
+		// no `@` after their userinfo, which is what makes the last one the boundary.
+		userinfo, hostAndTail := "", rest
+		if at := strings.LastIndex(rest, "@"); at >= 0 {
+			userinfo, hostAndTail = rest[:at+1], rest[at+1:]
 		}
-		userinfo := ""
-		if at := strings.LastIndex(authority, "@"); at >= 0 {
-			userinfo, authority = authority[:at+1], authority[at+1:]
+		authority, tail := hostAndTail, ""
+		if end := strings.IndexAny(hostAndTail, "/?#"); end >= 0 {
+			authority, tail = hostAndTail[:end], hostAndTail[end:]
 		}
 		host, err := hostWithPort(authority, port)
 		if err != nil {

internal/envfile/port_test.go

@@ -16,6 +16,7 @@ func TestAPortTwinMovesTheValuesPort(t *testing.T) {
 		"amqp://control:p%40ss@127.0.0.1:5672/":                           "amqp://control:p%40ss@127.0.0.1:6852/",
 		"amqp://control:p@ss:with@127.0.0.1:5672/":                        "amqp://control:p@ss:with@127.0.0.1:6852/",
 		"http://guest:guest@127.0.0.1:15672":                              "http://guest:guest@127.0.0.1:6852",
+		"postgres://mesh:a/b?c#d@e@127.0.0.1:5432/inventory":              "postgres://mesh:a/b?c#d@e@127.0.0.1:6852/inventory",
 		"http://[::1]:15672/api":                                          "http://[::1]:6852/api",
 		"broker.example:5671":                                             "broker.example:6852",
 		"broker.example":                                                  "broker.example:6852",
@@ -64,3 +65,14 @@ func TestAPortTwinThatIsNotAPortIsRefusedWithoutQuotingTheValue(t *testing.T) {
 		t.Fatal("a port with no value to put it on was accepted")
 	}
 }
+
+// A placeholder nothing filled is nothing said, not a fault: the control plane composing the
+// declaration may be one build behind the manifest, and refusing would leave it headless.
+func TestAnUnfilledPlaceholderIsNothingSaid(t *testing.T) {
+	t.Setenv("MESH_R", "postgres://m:p@127.0.0.1:5432/inventory")
+	t.Setenv("MESH_R_PORT", "${seat:mesh-store:5432}")
+	got, err := Placed("MESH_R")
+	if err != nil || got != "postgres://m:p@127.0.0.1:5432/inventory" {
+		t.Fatalf("an unfilled placeholder was not ignored: %q, %v", got, err)
+	}
+}

internal/store/manifest_test.go

@@ -0,0 +1,52 @@
+package store
+
+import (
+	"encoding/json"
+	"os"
+	"testing"
+)
+
+// **The manifest's placeholder, unfilled, reaches a store reader and changes nothing.**
+//
+// The control plane composes its own declaration, so the manifest naming `${seat:…}` can be
+// composed by a control plane one build older than it — one that passes the literal through as
+// the value. That is the state of the live control-node between this manifest landing and its
+// next build being pushed, and a reader that refused the literal would leave it headless
+// (novox/hq 04-ISSUES/102, finding F1). So the reader is held to ignoring exactly what
+// module.json says, not a placeholder shaped like it.
+func TestTheManifestsOwnPlaceholderUnfilledLeavesTheStoreWhereTheFileSays(t *testing.T) {
+	raw, err := os.ReadFile("../../module.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m struct {
+		Resources []struct {
+			Type string            `json:"type"`
+			Env  map[string]string `json:"env"`
+		} `json:"resources"`
+	}
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatal(err)
+	}
+	var written string
+	for _, r := range m.Resources {
+		if r.Type == "container" {
+			written = r.Env["MESH_STORE_INVENTORY_PORT"]
+		}
+	}
+	if written == "" {
+		t.Fatal("module.json no longer names MESH_STORE_INVENTORY_PORT")
+	}
+
+	alone(t)
+	t.Setenv(Variable(example), dsn)
+	t.Setenv(PortVariable(example), written)
+	opened, err := Open(t.Context(), example)
+	if err != nil {
+		t.Fatalf("the unfilled placeholder was refused, which is a headless control plane: %v", err)
+	}
+	defer opened.Close()
+	if got := opened.Pool().Config().ConnConfig.Port; got != 5432 {
+		t.Fatalf("the store is on %d; with the placeholder unfilled, the file's port stands", got)
+	}
+}