declaration: an access is mounted, and the host owns nothing about it

The tenth shape (novox/hq ADR 0051). Shared, pre-existing data — a media
library, a download spool several modules use — is the operator's, not
the mesh's. A `directory` resource is the host's own: it creates it,
chowns it, sets its mode and removes it when empty. An access is the
opposite on every axis.

Add the `access` type to the vocabulary. Its applier confirms the path is
present and changes nothing: it does not create, chown, reconcile or set
a mode. Absent is refused clearly — the operator must provide it — rather
than created, because a bind mount whose source is missing is made as
root by the container runtime with the wrong ownership (04-ISSUES/026).
Undeclaring an access forgets the record and never touches the path,
which is the data loss ADR 0030 prevents, on a directory the mesh never
made.

Full hosts speak it (it gates a bind mount, which needs the container
runtime); the vocabulary guard test records the decision that made it the
tenth shape. Unit tests cover present, absent-refused, and
undeclared-left-alone.

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

internal/apply/access_test.go

@@ -0,0 +1,98 @@
+package apply
+
+import (
+	"context"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-host/internal/store"
+)
+
+// An operator-owned path the module reaches but does not own (novox/hq ADR 0051).
+//
+// The host confirms it is present and changes nothing: it does not create it, chown it or set its
+// mode, because the media library and the download spool are the operator's and several modules
+// share them. This is the opposite of a directory on every axis, and the whole reason the two are
+// different shapes.
+func TestAnAccessPresentIsConfirmedAndNothingIsChanged(t *testing.T) {
+	dir := t.TempDir() // the operator's directory, already there
+	d := declare(t, `{"id":"lib","type":"access","path":"`+dir+`","mode":"read-write"}`)
+
+	report, _, err := Apply(context.Background(), archHost(t), d, store.State{},
+		store.OriginDeclared, noServices, nil, nil)
+	if err != nil {
+		t.Fatalf("an operator-owned path that is present was refused: %v", err)
+	}
+	if report.Changed() {
+		t.Fatalf("confirming an access reported a change; the host owns nothing about it")
+	}
+	if _, statErr := os.Stat(dir); statErr != nil {
+		t.Fatalf("the operator's directory was disturbed: %v", statErr)
+	}
+}
+
+// Absent is refused, not created. A bind mount whose source does not exist is made by the
+// container runtime as root, with whatever mode it picks — the silent wrong-ownership
+// 04-ISSUES/026 records. So the host says plainly that the operator must provide the path, rather
+// than conjuring a directory it does not own.
+func TestAnAccessThatIsAbsentIsRefusedClearlyAndNotCreated(t *testing.T) {
+	missing := t.TempDir() + "/media/library" // named, never created
+	d := declare(t, `{"id":"lib","type":"access","path":"`+missing+`"}`)
+
+	_, _, err := Apply(context.Background(), archHost(t), d, store.State{},
+		store.OriginDeclared, noServices, nil, nil)
+	if err == nil {
+		t.Fatal("an absent operator-owned path was accepted, and would be created as root by the runtime")
+	}
+	if !strings.Contains(err.Error(), "the operator must provide") ||
+		!strings.Contains(err.Error(), "does not own") {
+		t.Fatalf("the refusal does not say whose the path is: %v", err)
+	}
+	if _, statErr := os.Stat(missing); statErr == nil {
+		t.Fatal("the host created the path it does not own")
+	}
+}
+
+// Undeclaring an access never removes the path. Unassigning the module that reached the media
+// library must not delete the library — that is the data loss ADR 0030 exists to prevent, on a
+// directory the mesh never made. The record is dropped; the operator's data is left exactly as it
+// is.
+func TestAnUndeclaredAccessLeavesTheOperatorsPathAlone(t *testing.T) {
+	lib := t.TempDir() // the operator's library
+	keep := t.TempDir()
+	if err := os.WriteFile(lib+"/a-real-file", []byte("the operator's data"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	d := declare(t, `{"id":"lib","type":"access","path":"`+lib+`","mode":"read"}`)
+	_, state, err := Apply(context.Background(), archHost(t), d, store.State{},
+		store.OriginDeclared, noServices, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// The module is unassigned: the mesh no longer declares the access.
+	empty := declare(t, `{"id":"unrelated","type":"directory","path":"`+keep+`"}`)
+	report, _, err := Apply(context.Background(), archHost(t), empty, state,
+		store.OriginDeclared, noServices, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if _, statErr := os.Stat(lib); statErr != nil {
+		t.Fatalf("the operator's library was removed when the module stopped reaching it: %v", statErr)
+	}
+	if _, statErr := os.Stat(lib + "/a-real-file"); statErr != nil {
+		t.Fatalf("the operator's data was removed: %v", statErr)
+	}
+	var forgot bool
+	for _, o := range report.Outcomes {
+		if o.Type == "access" && o.Action == "forgotten" {
+			forgot = true
+		}
+	}
+	if !forgot {
+		t.Errorf("dropping an access was not reported as forgotten: %+v", report.Outcomes)
+	}
+}

internal/apply/apply.go

@@ -250,6 +250,8 @@ func applyOne(ctx context.Context, sys system.System, r declaration.Resource, ru
 		return applyAction(ctx, res, run)
 	case *declaration.Network:
 		return applyNetwork(ctx, res, run)
+	case *declaration.Access:
+		return applyAccess(res)
 	default:
 		// Unreachable: the declaration refused this already. Present because "unreachable"
 		// stops being true the moment someone adds a kind and forgets this switch.
@@ -336,6 +338,46 @@ func applyDirectory(r *declaration.Directory) (Outcome, error) {
 	return out, nil
 }
 
+// applyAccess confirms an operator-owned path is present, and owns nothing about it.
+//
+// **The mirror image of applyDirectory** (novox/hq ADR 0051). A directory the host makes, chmods,
+// chowns and removes when empty. An access it does none of: the path is the operator's — a media
+// library, a download spool that several modules share — and the host's only job is to be sure it
+// is there before anything mounts it.
+//
+// **Absent is refused, not created.** A bind mount whose source does not exist is made for you by
+// the container runtime, as root, with whatever mode it picks — which is exactly the silent
+// wrong-ownership 04-ISSUES/026 records. So the host checks first and says plainly that the
+// operator must provide the path, rather than conjuring a directory it does not own and cannot
+// give the right owner. Nothing is written, so this never reports a change: the machine did not
+// move, the host merely confirmed a fact about it.
+func applyAccess(r *declaration.Access) (Outcome, error) {
+	out := begin(r)
+	info, err := os.Stat(r.Path)
+	if errors.Is(err, os.ErrNotExist) {
+		return out, fmt.Errorf(
+			"%s is not there, and the mesh does not own it — the operator must provide it. It is "+
+				"shared, pre-existing data (novox/hq ADR 0051): the host mounts it and creates "+
+				"nothing, so a missing one is said here rather than made as root by the container "+
+				"runtime", r.Path)
+	}
+	if err != nil {
+		return out, err
+	}
+	if !info.IsDir() {
+		return out, fmt.Errorf(
+			"%s is not a directory, and an access is a shared directory the operator provides",
+			r.Path)
+	}
+	mode := declaration.AccessRead
+	if r.Mode != "" {
+		mode = r.Mode
+	}
+	out.Action = "unchanged"
+	out.Detail = "operator-owned; present, " + mode + ", nothing managed"
+	return out, nil
+}
+
 func applyFile(r *declaration.File, previous store.Applied, unseal Unseal) (Outcome, error) {
 	out := begin(r)
 
@@ -705,6 +747,13 @@ func remove(ctx context.Context, sys system.System, a store.Applied, run Runner)
 		// to whatever it acted on.
 		return "forgotten", "an action leaves nothing the host owns", nil
 
+	case declaration.TypeAccess:
+		// The path is the operator's and the host never owned it (novox/hq ADR 0051). Undeclaring
+		// it says only that this module no longer reaches it — not that the media library should
+		// be touched. So the record is dropped and the path left exactly as it is; removing it
+		// would be the data loss ADR 0030 exists to prevent, on a directory the mesh never made.
+		return "forgotten", "an operator-owned path is never the host's to remove", nil
+
 	case declaration.TypeNetwork:
 		// **The reason this is a shape at all** (novox/hq ADR 0029). Orphans are removed in
 		// reverse declaration order, so a network written before the containers that join it is