Merge pull request '57/P1: The node-engine knows who owns a placed file at runtime (issue 667)' (#109) from pkg/57-p1-ownership into feat/57-config-and-provisioning

cmd/mesh-host/main.go

@@ -1647,7 +1647,7 @@ func declaredResolvConf(d *declaration.Declaration) (string, string, bool) {
 	}
 	for _, r := range d.Resources {
 		f, ok := r.(*declaration.File)
-		if !ok || f.Path != network.ResolvConf || f.CreateOnce || f.Into != "" {
+		if !ok || f.Path != network.ResolvConf || f.Seeded() || f.Into != "" {
 			continue
 		}
 		module, ok := liveness.ModuleOf(f.ID)
@@ -1769,8 +1769,9 @@ func judgeWhatRuns(ctx context.Context, j *liveness.Judge, queue *link.Queue, sa
 func healthAsReported(st liveness.Statement, ns *network.Statement) *link.Health {
 	// LibraryContract: this engine reads a resource's declared `health` and judges it (ADR 0240 Phase B), judges a
 	// user's declared `root` (novox/hq ADR 0266), and reads a declaration's identities, groups and libraries
-	// (novox/hq ADR 0328), which is what tells the controller it may be sent any of those fields.
-	h := &link.Health{Contract: link.BusyContract, At: st.At.UTC(), Resources: []link.ResourceHealth{}}
+	// (novox/hq ADR 0328), a container's busy (ADR 0335) and a file's owner-at-runtime and the filled files (ADR
+	// 0349 §5), which is what tells the controller it may be sent any of those fields.
+	h := &link.Health{Contract: link.OwnershipContract, At: st.At.UTC(), Resources: []link.ResourceHealth{}}
 	for _, r := range st.Resources {
 		h.Resources = append(h.Resources, link.ResourceHealth{Module: r.Module, Resource: r.ID, Kind: r.Kind,
 			Target: r.Target, State: r.State, Reason: r.Reason, Since: r.Since.UTC(), Streak: r.Streak,

cmd/mesh-host/units_test.go

@@ -87,10 +87,10 @@ func TestTheStatementSaysAnAccountJudgedForRoot(t *testing.T) {
 			Groups: []string{"openrazer"}}, State: accounts.Healthy, Since: at},
 	}}
 	h := withAccounts(healthAsReported(liveness.Statement{At: at}, nil), as)
-	// At RootContract or later: an engine that also reads a container's busy says BusyContract (novox/hq ADR
-	// 0335), one above ADR 0334's OwnGroupContract.
-	if h.Contract < link.RootContract || link.RootContract != 3 || h.Contract != link.BusyContract ||
-		link.BusyContract != link.OwnGroupContract+1 {
+	// At RootContract or later: an engine that also reads a file's owner-at-runtime and the filled files says
+	// OwnershipContract (novox/hq ADR 0349 §5), one above ADR 0335's BusyContract.
+	if h.Contract < link.RootContract || link.RootContract != 3 || h.Contract != link.OwnershipContract ||
+		link.OwnershipContract != link.BusyContract+1 || link.BusyContract != link.OwnGroupContract+1 {
 		t.Fatalf("contract %d", h.Contract)
 	}
 	got := map[string]string{}

internal/apply/apply.go

@@ -1617,7 +1617,7 @@ func applyFile(r *declaration.File, previous store.Applied, unseal Unseal, keepF
 	// A seed that is already there is left exactly as it is — whatever has grown in it since is
 	// not the mesh's to put back (novox/hq issue 035). What this host records is what it once
 	// wrote, so a later declaration that changes the seed is not mistaken for drift either.
-	if r.CreateOnce && existed {
+	if r.Seeded() && existed {
 		out.wrote = previous.Wrote
 		if out.wrote == "" {
 			out.wrote = digestOf(string(existing))

internal/apply/ownership_test.go

@@ -0,0 +1,129 @@
+package apply
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/novox/mesh-host/internal/store"
+)
+
+// Defends novox/hq ADR 0349 §5 (issue 667): a file that says who owns it at runtime is written as the
+// form it names always was — owned as a whole file whose drift is written back, seed as create-once,
+// managed as only its keys or its marked block. Each is applied beside its old form, through the same
+// drift, and the two must end the same: the same actions, the same bytes on disk.
+
+// ownershipCase is one ownership word and the old form it maps onto.
+type ownershipCase struct {
+	name string
+	// said and old are the resource's fields after id, type and path: with the word, and in the old form.
+	said, old string
+	// before is what is at the path before the first apply; "" leaves the path absent.
+	before string
+	// drift is what the machine writes there between the two applies.
+	drift string
+	// first and second are the actions the old form is known to report.
+	first, second string
+}
+
+func TestEachOwnershipBehavesAsItsOldForm(t *testing.T) {
+	for _, c := range []ownershipCase{
+		{
+			name:  "owned is a whole file whose drift is written back",
+			said:  `"content":"correct\n","mode":"0644","owner-at-runtime":"owned"`,
+			old:   `"content":"correct\n","mode":"0644"`,
+			drift: "someone edited this\n",
+			first: "created", second: "corrected",
+		},
+		{
+			name:  "seed is written once and then the program's",
+			said:  `"content":"user default on\n","mode":"0600","owner-at-runtime":"seed"`,
+			old:   `"content":"user default on\n","mode":"0600","create-once":true`,
+			drift: "user default on\nuser app-one on\n",
+			first: "created", second: "kept",
+		},
+		{
+			name:   "managed json sets only its keys",
+			said:   `"into":"json","content":"{\"insecure-registries\":[\"10.42.0.1:5000\"]}","owner-at-runtime":"managed"`,
+			old:    `"into":"json","content":"{\"insecure-registries\":[\"10.42.0.1:5000\"]}"`,
+			before: machinesOwn,
+			drift:  `{"data-root":"/srv/other","log-opts":{"max-size":"10m"},"insecure-registries":["192.0.2.7:5000"]}`,
+			first:  "updated", second: "corrected",
+		},
+		{
+			name:   "managed block holds only its region",
+			said:   `"into":"block","content":"10.42.0.1 ace\n","owner-at-runtime":"managed"`,
+			old:    `"into":"block","content":"10.42.0.1 ace\n"`,
+			before: workstationHosts,
+			drift:  workstationHosts + "\n" + marked("f", "6.6.6.6 evil\n") + "192.0.2.9 the-machines-own\n",
+			first:  "updated", second: "corrected",
+		},
+	} {
+		t.Run(c.name, func(t *testing.T) {
+			saidActions, saidBytes := applyThroughDrift(t, c, c.said)
+			oldActions, oldBytes := applyThroughDrift(t, c, c.old)
+			if saidActions != oldActions {
+				t.Errorf("with the word the actions were %s; the old form's were %s", saidActions, oldActions)
+			}
+			if want := c.first + " " + c.second; oldActions != want {
+				t.Errorf("the old form's actions were %s; known to be %s", oldActions, want)
+			}
+			if saidBytes != oldBytes {
+				t.Errorf("with the word the file ends\n%q\nthe old form's ends\n%q", saidBytes, oldBytes)
+			}
+		})
+	}
+}
+
+// applyThroughDrift applies one file, lets the machine write the case's drift into it, applies again,
+// and says the two actions and what the file holds at the end.
+func applyThroughDrift(t *testing.T, c ownershipCase, fields string) (string, string) {
+	t.Helper()
+	path := filepath.Join(t.TempDir(), "the-file")
+	if c.before != "" {
+		if err := os.WriteFile(path, []byte(c.before), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	d := parse(t, fmt.Sprintf(`{"declaration":1,"resources":[{"id":"f","type":"file","path":%q,%s}]}`, path, fields))
+	first, state, err := Apply(context.Background(), archHost(t), d, store.State{}, store.OriginDeclared, noServices, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(path, []byte(c.drift), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	second, _, err := Apply(context.Background(), archHost(t), d, state, store.OriginDeclared, noServices, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return first.Outcomes[0].Action + " " + second.Outcomes[0].Action, readText(t, path)
+}
+
+// A seed said by the word alone, with no create-once beside it, is still kept once present: the word is
+// enough, and the file the program grew is not written back.
+func TestASeedByTheWordAloneKeepsWhatGrew(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "acl.conf")
+	d := parse(t, fmt.Sprintf(`{"declaration":1,"resources":[
+	  {"id":"acl","type":"file","path":%q,"content":"user default on\n","owner-at-runtime":"seed"}
+	]}`, path))
+	_, state, err := Apply(context.Background(), archHost(t), d, store.State{}, store.OriginDeclared, noServices, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(path, []byte("grown\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	report, _, err := Apply(context.Background(), archHost(t), d, state, store.OriginDeclared, noServices, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := report.Outcomes[0].Action; got != "kept" {
+		t.Errorf("a seed was %q", got)
+	}
+	if got := readText(t, path); got != "grown\n" {
+		t.Errorf("what grew in the seed was written over: %q", got)
+	}
+}

internal/declaration/declaration.go

@@ -237,8 +237,45 @@ type File struct {
 
 	// Owner is the user this belongs to, by name. Absent means root.
 	Owner string `json:"owner,omitempty"`
+
+	// OwnerAtRuntime says who owns the file once it is placed (novox/hq ADR 0349 §5): "owned", the mesh's
+	// whole, written back whenever it differs; "seed", written once and then the program's; or "managed",
+	// only its named keys or its marked block the mesh's, the program keeping the rest.
+	//
+	// **Three words for what the forms above already do.** Owned is an ordinary file, seed is create-once
+	// and managed is a file written into, so the word changes no write: a file that says it is applied
+	// exactly as its old form is, and one that does not say is owned by its old form (Ownership). The word
+	// is what the provisioner's files say of themselves, which the old forms only implied. Seed is enough
+	// alone; managed still needs `into`, which says the format. A word that contradicts the form is refused.
+	OwnerAtRuntime string `json:"owner-at-runtime,omitempty"`
 }
 
+// The words a file says who owns it at runtime with (novox/hq ADR 0349 §5).
+const (
+	RuntimeOwned   = "owned"
+	RuntimeSeed    = "seed"
+	RuntimeManaged = "managed"
+)
+
+// Ownership is who owns the file at runtime: the word it says, or the one its old form implies — a file
+// written into is managed, one created once is a seed, and any other is owned.
+func (f *File) Ownership() string {
+	switch {
+	case f.OwnerAtRuntime != "":
+		return f.OwnerAtRuntime
+	case f.Into != "":
+		return RuntimeManaged
+	case f.CreateOnce:
+		return RuntimeSeed
+	default:
+		return RuntimeOwned
+	}
+}
+
+// Seeded reports whether the file is written only when absent: created once, by create-once or by the
+// word seed.
+func (f *File) Seeded() bool { return f.CreateOnce || f.OwnerAtRuntime == RuntimeSeed }
+
 // Secret reports whether this file arrived sealed, which is what decides both that it must be
 // opened before writing and that its contents must never appear in a report.
 func (f *File) Secret() bool { return f.Sealed != "" }
@@ -320,6 +357,7 @@ func (f *File) validate(where string, _ bool) []string {
 				"secrets or create-once")
 		}
 	}
+	problems = append(problems, f.checkOwnership(where)...)
 	var said []string
 	for name, value := range map[string]string{
 		"content": f.Content, "sealed": f.Sealed, "bytes": f.Bytes,
@@ -361,6 +399,42 @@ func (f *File) validate(where string, _ bool) []string {
 	return append(problems, checkMode(where, f.Mode)...)
 }
 
+// checkOwnership refuses a word that contradicts the file's form (novox/hq ADR 0349 §5): owned is a whole
+// file written back, so not created once nor written into; a seed is a whole file created once, so not
+// written into; managed is a file written into, which says its format. Managed and created once together
+// is already refused by the rule that a file written into is not created once.
+func (f *File) checkOwnership(where string) []string {
+	switch f.OwnerAtRuntime {
+	case "":
+	case RuntimeOwned:
+		var also []string
+		if f.CreateOnce {
+			also = append(also, "create-once")
+		}
+		if f.Into != "" {
+			also = append(also, "into")
+		}
+		if len(also) > 0 {
+			return []string{fmt.Sprintf("%s: owned at runtime is the mesh's whole file, written back whenever it "+
+				"differs, and this also says %s", where, strings.Join(also, " and "))}
+		}
+	case RuntimeSeed:
+		if f.Into != "" {
+			return []string{where + ": a seed is a whole file written once, and this says into; a file the " +
+				"program shares with the mesh is managed"}
+		}
+	case RuntimeManaged:
+		if f.Into == "" {
+			return []string{where + ": a managed file names the format its keys or block are written into, " +
+				"with into \"json\" or \"block\""}
+		}
+	default:
+		return []string{fmt.Sprintf("%s: owner-at-runtime %q; a placed file is %q, %q or %q, or omits it to be "+
+			"owned by its form", where, f.OwnerAtRuntime, RuntimeOwned, RuntimeSeed, RuntimeManaged)}
+	}
+	return nil
+}
+
 // User is a login on the machine.
 //
 // The thing that makes a shell, a chat client or a desktop expressible at all: each is a package
@@ -1565,6 +1639,52 @@ type Declaration struct {
 	// this is its home, whether the operator's warrant to take it was carried out, the sub-paths its modules ask for,
 	// and the tool runner's account to put in its group (§11). Absent is a controller older than ADR 0328.
 	Libraries []Library
+
+	// Filled is the paths of the files the provisioner fills on this machine (novox/hq ADR 0349 §4, §5): each a
+	// file this declaration declares, which says who owns it at runtime. The provisioner's client has the
+	// node-engine write only these. Absent is a controller that hands no file to the provisioner, and every
+	// file is written from the declaration as before.
+	Filled []string
+}
+
+// Fills reports whether the provisioner fills the file at path on this machine.
+func (d *Declaration) Fills(path string) bool { return slices.Contains(d.Filled, path) }
+
+// checkFilled refuses a filled path that is not a declared file saying who owns it at runtime, or that is named
+// twice or empty. Every file declared at the path must say it: the provisioner writes the path, and a file there
+// the mesh writes some other way would be a second writer of it (ADR 0349 §5).
+func checkFilled(filled []string, resources []Resource) []string {
+	var problems []string
+	files := map[string][]*File{}
+	for _, r := range resources {
+		if f, ok := r.(*File); ok {
+			files[f.Path] = append(files[f.Path], f)
+		}
+	}
+	seen := map[string]bool{}
+	for _, path := range filled {
+		switch {
+		case path == "":
+			problems = append(problems, "filled_files names a file with no path")
+			continue
+		case seen[path]:
+			problems = append(problems, fmt.Sprintf("filled_files names %q twice", path))
+			continue
+		}
+		seen[path] = true
+		if len(files[path]) == 0 {
+			problems = append(problems, fmt.Sprintf("filled_files names %q, and this declaration declares no "+
+				"file there", path))
+			continue
+		}
+		for _, f := range files[path] {
+			if f.OwnerAtRuntime == "" {
+				problems = append(problems, fmt.Sprintf("resource %q: the provisioner fills %q, and a file it "+
+					"fills says who owns it at runtime with owner-at-runtime", f.ID, path))
+			}
+		}
+	}
+	return problems
 }
 
 // Identity is one module's identity, as the controller allocated it (ADR 0328 §4): its user `mesh-<module>` with
@@ -1904,6 +2024,9 @@ type envelope struct {
 	// sends them only to a host whose health says link.LibraryContract.
 	Groups    []Group   `json:"groups,omitempty"`
 	Libraries []Library `json:"libraries,omitempty"`
+	// Filled is optional too (novox/hq ADR 0349 §5), as is a file's `owner-at-runtime`. **An older host refuses
+	// these keys**; a controller sends them only to a host whose health says link.OwnershipContract.
+	Filled []string `json:"filled_files,omitempty"`
 }
 
 func parse(raw []byte, allowActions bool) (*Declaration, error) {
@@ -1922,7 +2045,7 @@ func parse(raw []byte, allowActions bool) (*Declaration, error) {
 
 	d := &Declaration{Version: env.Version, For: env.For, Adoption: env.Adoption, Sequence: env.Sequence,
 		Epoch: env.Epoch, LeftOut: env.LeftOut, Generation: env.Generation, PutBack: env.PutBack,
-		Identities: env.Identities, Groups: env.Groups, Libraries: env.Libraries}
+		Identities: env.Identities, Groups: env.Groups, Libraries: env.Libraries, Filled: env.Filled}
 	problems := checkIdentities(env.Identities, env.Groups)
 	problems = append(problems, checkLibraries(env.Groups, env.Libraries)...)
 	if env.Generation < 0 {
@@ -2015,6 +2138,7 @@ func parse(raw []byte, allowActions bool) (*Declaration, error) {
 	problems = append(problems, checkWhileStopped(d.Resources)...)
 	problems = append(problems, checkAdoption(env.Adoption, d.Resources, allowActions)...)
 	problems = append(problems, checkReplaces(d.Resources)...)
+	problems = append(problems, checkFilled(env.Filled, d.Resources)...)
 	if env.Adoption == nil {
 		for _, r := range d.Resources {
 			if r.Kind() == TypeOpening {

internal/declaration/ownership_test.go

@@ -0,0 +1,130 @@
+package declaration
+
+import (
+	"strings"
+	"testing"
+)
+
+// Defends novox/hq ADR 0349 §5 (issue 667): a file the provisioner places says who owns it at runtime
+// — owned, seed or managed — and the declaration names the files the provisioner fills. The words are
+// read and judged here before any controller sends them.
+
+func TestAFileSaysWhoOwnsItAtRuntime(t *testing.T) {
+	d, err := Parse([]byte(`{"declaration":1,"resources":[
+	  {"id":"o","type":"file","path":"/etc/o","content":"a","owner-at-runtime":"owned"},
+	  {"id":"s","type":"file","path":"/etc/s","content":"a","owner-at-runtime":"seed"},
+	  {"id":"s2","type":"file","path":"/etc/s2","content":"a","owner-at-runtime":"seed","create-once":true},
+	  {"id":"mj","type":"file","path":"/etc/mj","into":"json","content":"{\"k\":1}","owner-at-runtime":"managed"},
+	  {"id":"mb","type":"file","path":"/etc/mb","into":"block","content":"a\n","owner-at-runtime":"managed"}
+	]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := map[string]string{"o": RuntimeOwned, "s": RuntimeSeed, "s2": RuntimeSeed, "mj": RuntimeManaged,
+		"mb": RuntimeManaged}
+	for _, r := range d.Resources {
+		f := r.(*File)
+		if f.OwnerAtRuntime != want[f.ID] || f.Ownership() != want[f.ID] {
+			t.Errorf("%s: read as %q, ownership %q; want %q", f.ID, f.OwnerAtRuntime, f.Ownership(), want[f.ID])
+		}
+	}
+}
+
+// A file that does not say is owned by its old form, so the word means exactly what that form does.
+func TestAFileThatDoesNotSayIsOwnedByItsOldForm(t *testing.T) {
+	d, err := Parse([]byte(`{"declaration":1,"resources":[
+	  {"id":"o","type":"file","path":"/etc/o","content":"a"},
+	  {"id":"s","type":"file","path":"/etc/s","content":"a","create-once":true},
+	  {"id":"mj","type":"file","path":"/etc/mj","into":"json","content":"{}"},
+	  {"id":"mb","type":"file","path":"/etc/mb","into":"block","content":"a\n"}
+	]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := map[string]string{"o": RuntimeOwned, "s": RuntimeSeed, "mj": RuntimeManaged, "mb": RuntimeManaged}
+	for _, r := range d.Resources {
+		f := r.(*File)
+		if f.OwnerAtRuntime != "" || f.Ownership() != want[f.ID] {
+			t.Errorf("%s: said %q, ownership %q; want unsaid and %q", f.ID, f.OwnerAtRuntime, f.Ownership(), want[f.ID])
+		}
+		if f.Seeded() != (want[f.ID] == RuntimeSeed) {
+			t.Errorf("%s: seeded %v", f.ID, f.Seeded())
+		}
+	}
+}
+
+func TestAnOwnershipThatContradictsTheFileIsRefused(t *testing.T) {
+	for name, c := range map[string]struct{ resource, refusal string }{
+		"another word": {`{"id":"f","type":"file","path":"/etc/x","content":"a","owner-at-runtime":"mine"}`,
+			`owner-at-runtime "mine"`},
+		"owned and create-once": {`{"id":"f","type":"file","path":"/etc/x","content":"a","owner-at-runtime":"owned","create-once":true}`,
+			"create-once"},
+		"owned and into": {`{"id":"f","type":"file","path":"/etc/x","into":"json","content":"{}","owner-at-runtime":"owned"}`,
+			"into"},
+		"seed and into": {`{"id":"f","type":"file","path":"/etc/x","into":"block","content":"a","owner-at-runtime":"seed"}`,
+			"into"},
+		"managed and whole": {`{"id":"f","type":"file","path":"/etc/x","content":"a","owner-at-runtime":"managed"}`,
+			"into"},
+		"managed and create-once": {`{"id":"f","type":"file","path":"/etc/x","into":"json","content":"{}","owner-at-runtime":"managed","create-once":true}`,
+			"create-once"},
+		// The rule that was there before stays: a file written into is never sealed or created once.
+		"managed and sealed": {`{"id":"f","type":"file","path":"/etc/x","into":"json","content":"{}","sealed":"x","owner-at-runtime":"managed"}`,
+			"sealed"},
+	} {
+		_, err := Parse([]byte(`{"declaration":1,"resources":[` + c.resource + `]}`))
+		if err == nil || !strings.Contains(err.Error(), c.refusal) {
+			t.Errorf("%s: want a refusal naming %q, got %v", name, c.refusal, err)
+		}
+	}
+}
+
+func TestTheDeclarationNamesTheFilesTheProvisionerFills(t *testing.T) {
+	d, err := Parse([]byte(`{"declaration":1,"filled_files":["/etc/a","/etc/b"],"resources":[
+	  {"id":"a","type":"file","path":"/etc/a","content":"a","owner-at-runtime":"owned"},
+	  {"id":"b","type":"file","path":"/etc/b","into":"block","content":"b\n","owner-at-runtime":"managed"},
+	  {"id":"c","type":"file","path":"/etc/c","content":"c"}
+	]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(d.Filled) != 2 || d.Filled[0] != "/etc/a" || d.Filled[1] != "/etc/b" {
+		t.Fatalf("filled files read as %v", d.Filled)
+	}
+	if !d.Fills("/etc/a") || !d.Fills("/etc/b") || d.Fills("/etc/c") {
+		t.Errorf("Fills: a %v, b %v, c %v", d.Fills("/etc/a"), d.Fills("/etc/b"), d.Fills("/etc/c"))
+	}
+
+	// A declaration that names none fills none, as every declaration before this did.
+	d, err = Parse([]byte(`{"declaration":1,"resources":[{"id":"c","type":"file","path":"/etc/c","content":"c"}]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if d.Filled != nil || d.Fills("/etc/c") {
+		t.Errorf("a declaration naming no filled files fills %v", d.Filled)
+	}
+}
+
+func TestAFilledFileMustBeADeclaredFileThatSaysItsOwner(t *testing.T) {
+	for name, c := range map[string]struct{ filled, resources, refusal string }{
+		"not declared": {`["/etc/none"]`,
+			`{"id":"a","type":"file","path":"/etc/a","content":"a","owner-at-runtime":"owned"}`,
+			`"/etc/none"`},
+		"a directory, not a file": {`["/etc/d"]`,
+			`{"id":"d","type":"directory","path":"/etc/d"}`,
+			`"/etc/d"`},
+		"says no owner": {`["/etc/a"]`,
+			`{"id":"a","type":"file","path":"/etc/a","content":"a"}`,
+			"owner-at-runtime"},
+		"named twice": {`["/etc/a","/etc/a"]`,
+			`{"id":"a","type":"file","path":"/etc/a","content":"a","owner-at-runtime":"owned"}`,
+			"twice"},
+		"no path": {`[""]`,
+			`{"id":"a","type":"file","path":"/etc/a","content":"a","owner-at-runtime":"owned"}`,
+			"no path"},
+	} {
+		_, err := Parse([]byte(`{"declaration":1,"filled_files":` + c.filled + `,"resources":[` + c.resources + `]}`))
+		if err == nil || !strings.Contains(err.Error(), c.refusal) {
+			t.Errorf("%s: want a refusal naming %q, got %v", name, c.refusal, err)
+		}
+	}
+}

internal/link/messages.go

@@ -295,6 +295,13 @@ const OwnGroupContract = 7
 // for it.
 const BusyContract = 8
 
+// OwnershipContract is the statement of a host that also reads a file's `owner-at-runtime` and a declaration's
+// `filled_files` (novox/hq ADR 0349 §5): it writes an owned file back on drift, a seed once and a managed file's
+// keys or block only, exactly as their old forms, and refuses a filled path that is not a declared file saying
+// its owner. Like the fields before it, its presence is what tells the controller this host may be sent those
+// fields; an older host refuses the whole declaration for them.
+const OwnershipContract = 9
+
 // Health is one statement of every long-running resource's state on this machine (to-be 48 §4). Said in
 // every report, as an event on each change, and again every minute while anything is not healthy — so a
 // lost statement is not a lost fault.

validate/validate_test.go

@@ -18,7 +18,14 @@ func TestTheValidatorIsTheHosts(t *testing.T) {
 	if problems := Declaration([]byte(ordered)); problems != nil {
 		t.Fatalf("a declaration carrying its order was refused: %v", problems)
 	}
+	// And one carrying a file's owner-at-runtime and the files the provisioner fills (novox/hq ADR 0349 §5): the
+	// reader takes them before any controller sends them.
+	owned := `{"declaration": 1, "filled_files": ["/etc/x"], "resources": [{"id": "f", "type": "file", "path": "/etc/x", "content": "a", "owner-at-runtime": "owned"}]}`
+	if problems := Declaration([]byte(owned)); problems != nil {
+		t.Fatalf("a declaration saying who owns a file at runtime was refused: %v", problems)
+	}
 	for _, bad := range []string{
+		`{"declaration": 1, "filled_files": ["/etc/none"], "resources": [{"id": "f", "type": "file", "path": "/etc/x", "content": "a", "owner-at-runtime": "owned"}]}`,
 		`{"declaration": 1, "resources": []}`,
 		`{"declaration": 99, "resources": [{"id": "d", "type": "directory", "path": "/x"}]}`,
 		`{"declaration": 1, "resources": [{"id": "d", "type": "nothing-the-host-knows"}]}`,