Merge pull request '57/T1: A file resource may name a template file in its module's repository (issue 654)' (#313) from pkg/57-t1-template-files into feat/57-config-and-provisioning

cmd/mesh-controller/check.go

@@ -55,6 +55,11 @@ func moduleCheckFor(paths []string, longestMachine int, out io.Writer) error {
 			continue
 		}
 		m, err := catalogue.ParseManifest(raw)
+		if err == nil {
+			// Each template's text read from the tree beside the manifest, and judged as inline content is
+			// (novox/hq ADR 0349 §2): a missing template is refused by name.
+			m, err = catalogue.WithTemplatesFrom(m, filepath.Dir(path))
+		}
 		if err != nil {
 			fmt.Fprintf(out, "%s: %v\n", path, err)
 			failed++

cmd/mesh-controller/merge_gate.go

@@ -576,6 +576,11 @@ func shelfWithChange(base map[string]catalogue.Manifest, sources map[string]inve
 			return err
 		}
 		m, err := catalogue.ParseManifest(raw)
+		if err == nil {
+			// Each template's text from the tree beside the manifest, as the build reads it back from the archive it
+			// packs (novox/hq ADR 0349 §2): so a change to a template alone is a change to its module.
+			m, err = catalogue.WithTemplatesFrom(m, filepath.Dir(path))
+		}
 		if err != nil {
 			if inScope(dir) {
 				failures = append(failures, fmt.Sprintf("%s: the controller judging this (%s) refuses it — %s",

cmd/mesh-controller/modules.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net"
 	"os"
+	"path/filepath"
 	"sort"
 	"strings"
 	"time"
@@ -127,6 +128,10 @@ func moduleCommand(ctx context.Context, args []string) error {
 		if err != nil {
 			return err
 		}
+		// A manifest handed over by hand takes each template's text from the tree beside it (novox/hq ADR 0349 §2).
+		if m, err = catalogue.WithTemplatesFrom(m, filepath.Dir(positionals[0])); err != nil {
+			return err
+		}
 		from, err := whereItComesFrom(*repo, *ref, *commit, *path, *self)
 		if err != nil {
 			return err

cmd/mesh-controller/template_test.go

@@ -0,0 +1,204 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	snapshot "github.com/novox/mesh-controller/internal/facts"
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// A file's text kept as a template file in its module's repository (novox/hq ADR 0349 §2, design 57 package T1,
+// issue 654): `module check` and the merge gate read it from the tree beside the manifest, so a change to a
+// template alone is judged as a change to its module.
+
+const templatedNotifier = `{"module":"notifier","version":"1",
+  "build":{"artifacts":[{"name":"files","kind":"archive","from":"files"}]},
+  "resources":[{"id":"conf","type":"file","path":"/etc/notifier/notifier.conf","mode":"0644","template":"files/notifier.conf"}]}`
+
+// inlineNotifier is the same module as the mesh holds it: built, its text inline.
+const inlineNotifier = `{"module":"notifier","version":"1",
+  "resources":[{"id":"conf","type":"file","path":"/etc/notifier/notifier.conf","mode":"0644","content":"volume = 3\n"}]}`
+
+// aTemplatedModule writes a module's directory: its manifest and its files/.
+func aTemplatedModule(t *testing.T, dir, manifest string, files map[string]string) string {
+	t.Helper()
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	path := filepath.Join(dir, "module.json")
+	if err := os.WriteFile(path, []byte(manifest), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	for name, text := range files {
+		full := filepath.Join(dir, filepath.FromSlash(name))
+		if err := os.MkdirAll(filepath.Dir(full), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(full, []byte(text), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	return path
+}
+
+func TestModuleCheckReadsTemplatesFromTheTreeBesideTheManifest(t *testing.T) {
+	good := aTemplatedModule(t, t.TempDir(), templatedNotifier, map[string]string{"files/notifier.conf": "volume = 3\n"})
+	var out bytes.Buffer
+	if err := moduleCheck([]string{good}, &out); err != nil || !strings.Contains(out.String(), "notifier: ok") {
+		t.Fatalf("a module with its text in files/ was refused: %v\n%s", err, out.String())
+	}
+
+	// A change to the template alone, to text the controller refuses inline, is refused the same.
+	bad := aTemplatedModule(t, t.TempDir(), templatedNotifier,
+		map[string]string{"files/notifier.conf": "volume = 3\nstore = ${dir:nowhere}\n"})
+	out.Reset()
+	if err := moduleCheck([]string{bad}, &out); err == nil || !strings.Contains(out.String(), "nowhere") {
+		t.Fatalf("a template whose text is refused inline passed:\n%s", out.String())
+	}
+
+	// A symlink under files/ that no template names: the build's packing refuses it, so the check does too.
+	linked := t.TempDir()
+	aTemplatedModule(t, linked, templatedNotifier, map[string]string{"files/notifier.conf": "volume = 3\n"})
+	if err := os.Symlink("/etc/hostname", filepath.Join(linked, "files", "elsewhere")); err != nil {
+		t.Fatal(err)
+	}
+	out.Reset()
+	if err := moduleCheck([]string{filepath.Join(linked, "module.json")}, &out); err == nil ||
+		!strings.Contains(out.String(), "files/elsewhere is a symlink") {
+		t.Fatalf("a symlink under files/ passed the check:\n%s", out.String())
+	}
+
+	// And a template the tree lacks, by name.
+	missing := aTemplatedModule(t, t.TempDir(), templatedNotifier, nil)
+	out.Reset()
+	if err := moduleCheck([]string{missing}, &out); err == nil || !strings.Contains(out.String(), "files/notifier.conf") {
+		t.Fatalf("a missing template was not refused by name:\n%s", out.String())
+	}
+}
+
+// templatedMesh is catalogueMesh with the notifier on the laptop, registered as built: its text inline.
+func templatedMesh(t *testing.T) (snapshot.Facts, map[string]string) {
+	t.Helper()
+	open := aMesh(t)
+	ctx := t.Context()
+	manifests := map[string]string{
+		"lemurs": `{"module":"lemurs","version":"1","capabilities":["systemd"],
+			"resources":[{"id":"service","type":"service","unit":"lemurs.service","state":"running","boot":"enabled"}]}`,
+		"notifier": inlineNotifier,
+	}
+	for name, raw := range manifests {
+		m, err := catalogue.ParseManifest([]byte(raw))
+		if err != nil {
+			t.Fatalf("%s: %v", name, err)
+		}
+		if err := open.inventory.RegisterModule(ctx, m, inventory.Source{Repository: "novox/mesh-catalog",
+			Path: "modules/" + name, BuiltFrom: "c0ffee"}); err != nil {
+			t.Fatal(err)
+		}
+		if _, err := assign(ctx, open, "laptop", name); err != nil {
+			t.Fatalf("assign %s: %v", name, err)
+		}
+	}
+	f, err := gatherFacts(ctx, open, "2.11.17")
+	if err != nil {
+		t.Fatal(err)
+	}
+	return f, manifests
+}
+
+// aTemplatedTree is the catalogue's checkout with the notifier's text in files/.
+func aTemplatedTree(t *testing.T, manifests map[string]string, text string, has bool) string {
+	t.Helper()
+	tree := aTree(t, withEdit(manifests, "notifier", ""))
+	files := map[string]string{}
+	if has {
+		files["files/notifier.conf"] = text
+	}
+	aTemplatedModule(t, filepath.Join(tree, "modules", "notifier"), templatedNotifier, files)
+	return tree
+}
+
+const notifierTemplate = "modules/notifier/files/notifier.conf"
+
+func TestTheMergeGateJudgesAChangeToATemplateAlone(t *testing.T) {
+	f, manifests := templatedMesh(t)
+
+	// The module moved to its template, the same text: nothing changes on any machine.
+	v := gateJudged(t, f, aTemplatedTree(t, manifests, "volume = 3\n", true), "modules/notifier/module.json",
+		notifierTemplate)
+	if v.Verdict == "fail" || v.Modules["notifier"] != "" {
+		t.Fatalf("the module moved to its template with the same text reads as a change (%v):\n%s", v.Modules, v.Report())
+	}
+
+	// The template alone changed: its module changed, and composes.
+	v = gateJudged(t, f, aTemplatedTree(t, manifests, "volume = 4\n", true), notifierTemplate)
+	if v.Verdict == "fail" || v.Modules["notifier"] != "changed" {
+		t.Fatalf("a change to the template alone is not a change to its module (%v):\n%s", v.Modules, v.Report())
+	}
+	if v.Width == nil || strings.Join(v.Width.Modules, ",") != "notifier" {
+		t.Fatalf("a change to the template rebuilds %+v, not its module", v.Width)
+	}
+
+	// The template alone changed to text the controller refuses: the pull request fails, naming the module.
+	v = gateJudged(t, f, aTemplatedTree(t, manifests, "store = ${dir:nowhere}\n", true), notifierTemplate)
+	if v.Verdict != "fail" || !strings.Contains(v.Report(), "notifier") {
+		t.Fatalf("a template the controller refuses passed the gate:\n%s", v.Report())
+	}
+
+	// A symlinked files/ fails: nothing is read from outside the tree.
+	tree := aTree(t, withEdit(manifests, "notifier", ""))
+	elsewhere := t.TempDir()
+	if err := os.WriteFile(filepath.Join(elsewhere, "notifier.conf"), []byte("volume = 3\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	aTemplatedModule(t, filepath.Join(tree, "modules", "notifier"), templatedNotifier, nil)
+	if err := os.Symlink(elsewhere, filepath.Join(tree, "modules", "notifier", "files")); err != nil {
+		t.Fatal(err)
+	}
+	v = gateJudged(t, f, tree, notifierTemplate)
+	if v.Verdict != "fail" || !strings.Contains(v.Report(), "files/ is a symlink") {
+		t.Fatalf("a symlinked files/ passed the gate:\n%s", v.Report())
+	}
+
+	// And the template removed from the tree fails, naming it.
+	v = gateJudged(t, f, aTemplatedTree(t, manifests, "", false), notifierTemplate)
+	if v.Verdict != "fail" || !strings.Contains(v.Report(), "files/notifier.conf") {
+		t.Fatalf("a missing template passed the gate:\n%s", v.Report())
+	}
+}
+
+// What the gate composes for the module in its template form is what the mesh composes for it inline.
+func TestTheMergeGateResolvesATemplatedModuleToItsInlineTwin(t *testing.T) {
+	dir := t.TempDir()
+	path := aTemplatedModule(t, dir, templatedNotifier, map[string]string{"files/notifier.conf": "volume = 3\n"})
+	raw, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	m, err := catalogue.ParseManifest(raw)
+	if err != nil {
+		t.Fatal(err)
+	}
+	m, err = catalogue.WithTemplatesFrom(m, dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	resolved, err := standInBuild(m)
+	if err != nil {
+		t.Fatal(err)
+	}
+	inline, err := catalogue.ParseManifest([]byte(inlineNotifier))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if builtAlike(resolved) != builtAlike(inline) {
+		got, _ := json.Marshal(resolved)
+		t.Fatalf("the templated module resolves to %s, not its inline twin", got)
+	}
+}

internal/builder/builder.go

@@ -268,7 +268,14 @@ func build(ctx context.Context, run Runner, publish Publisher,
 	}
 	// What is judged only where a definition is written (novox/hq ADR 0326 §3, issue 574): a build is
 	// where a changed definition is first read, so it is refused here before anything is made of it.
-	if problems := catalogue.WrittenSettingsProblems(manifest); len(problems) > 0 {
+	// Judged with each template's text in its file, as written in the tree (novox/hq ADR 0349 §2): a template the
+	// module's directory lacks is refused here, before anything is built.
+	judged, err := catalogue.WithTemplatesFrom(manifest, within)
+	if err != nil {
+		say("manifest", "INVALID: %v", err)
+		return Result{}, err
+	}
+	if problems := catalogue.WrittenSettingsProblems(judged); len(problems) > 0 {
 		err := fmt.Errorf("%s", strings.Join(problems, "; "))
 		say("manifest", "INVALID: %v", err)
 		return Result{}, err
@@ -410,6 +417,11 @@ func build(ctx context.Context, run Runner, publish Publisher,
 		}
 	}
 
+	// Each template's text, read back from the archive the build made or took (novox/hq ADR 0349 §2).
+	if built, err = withTemplateTexts(manifest, within, built); err != nil {
+		say("templates", "FAILED: %v", err)
+		return Result{}, err
+	}
 	resolved, err := manifest.Resolve(built)
 	if err != nil {
 		say("resolve", "FAILED: %v", err)

internal/builder/reuse_test.go

@@ -73,8 +73,14 @@ const reusedModule = `{"module":"meshboard","version":"1",
 // aModuleAt is a repository holding the module under mod/, whose directory git names as tree, on its trunk.
 func aModuleAt(t *testing.T, tree string) (*recorded, Runner, string) {
 	t.Helper()
-	r := &recorded{tree: tree, contents: map[string]string{"mod/" + ManifestName: reusedModule,
+	return aModuleWith(t, tree, map[string]string{"mod/" + ManifestName: reusedModule,
-		"mod/Dockerfile": "FROM scratch", "mod/files/theme.conf": "dark"}}
+		"mod/Dockerfile": "FROM scratch", "mod/files/theme.conf": "dark"})
+}
+
+// aModuleWith is aModuleAt with the repository's files given.
+func aModuleWith(t *testing.T, tree string, contents map[string]string) (*recorded, Runner, string) {
+	t.Helper()
+	r := &recorded{tree: tree, contents: contents}
 	run := func(ctx context.Context, dir, name string, args ...string) (string, error) {
 		if name == "git" && len(args) > 0 && args[0] == "symbolic-ref" {
 			r.ran = append(r.ran, name+" "+strings.Join(args, " "))
@@ -100,6 +106,12 @@ var aPull = PullRef{Owner: "novox", Repo: "meshboard", Number: 7}
 func aCheckBuilt(t *testing.T, scratch *aScratch, tree string) CheckBuilt {
 	t.Helper()
 	r, run, workspace := aModuleAt(t, tree)
+	return aCheckBuiltBy(t, scratch, r, run, workspace)
+}
+
+// aCheckBuiltBy is aCheckBuilt of the repository given.
+func aCheckBuiltBy(t *testing.T, scratch *aScratch, r *recorded, run Runner, workspace string) CheckBuilt {
+	t.Helper()
 	spec := CheckSpec{ID: "build-1", Owner: aPull.Owner, Repo: aPull.Repo, Number: aPull.Number,
 		Builds: []CheckBuildSpec{{Module: "meshboard", Repository: "https://forge.invalid/meshboard.git", Path: "mod",
 			Ref: "main"}}}

internal/builder/template.go

@@ -0,0 +1,94 @@
+package builder
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"path/filepath"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+)
+
+// withTemplateTexts is what was built with each template's text, for a module whose files name templates
+// (novox/hq ADR 0349 §2): its templates archive gains the text of every file in it, read back from the packed
+// bytes, by its path inside the archive. Resolve reads them into the files' content.
+//
+// **Read from the archive, proven by its digest.** The module's files/ is packed again, as the build packs it,
+// and the bytes are read only when they hash to the digest the build made or took: a fresh build's own archive,
+// or a check's build a walk copied by digest without building (novox/hq ADR 0350 §2). Packing is deterministic,
+// so one source packs to one digest; a tree that packs to another is not the archive, and its text is refused.
+func withTemplateTexts(manifest catalogue.Manifest, within string, built []catalogue.Built) ([]catalogue.Built, error) {
+	if !manifest.Templated() {
+		return built, nil
+	}
+	name := catalogue.TemplatesArtifact(manifest)
+	at := -1
+	for i, b := range built {
+		if b.Name == name {
+			at = i
+		}
+	}
+	if name == "" || at < 0 {
+		return nil, fmt.Errorf("%s names templates and built no archive of %s/ to read them from",
+			manifest.Module, catalogue.TemplatesDir)
+	}
+	body, err := pack(filepath.Join(within, catalogue.TemplatesDir))
+	if err != nil {
+		return nil, fmt.Errorf("%s: packing %s/ to read its templates back failed: %w", manifest.Module,
+			catalogue.TemplatesDir, err)
+	}
+	sum := sha256.Sum256(body)
+	digest := "sha256:" + hex.EncodeToString(sum[:])
+	if built[at].Digest != digest {
+		return nil, fmt.Errorf("%s: %s/ packs to the digest %s, and the archive %q built or taken is %s: the "+
+			"templates are read only from the archive the mesh records", manifest.Module, catalogue.TemplatesDir,
+			digest, name, orNone(built[at].Digest))
+	}
+	texts, err := unpackTexts(body)
+	if err != nil {
+		return nil, fmt.Errorf("%s: reading the archive %q back failed: %w", manifest.Module, name, err)
+	}
+	out := append([]catalogue.Built(nil), built...)
+	out[at].Texts = texts
+	return out, nil
+}
+
+// unpackTexts is every file of a packed archive (pack), by its path inside it.
+func unpackTexts(body []byte) (map[string]string, error) {
+	zipped, err := gzip.NewReader(bytes.NewReader(body))
+	if err != nil {
+		return nil, err
+	}
+	defer zipped.Close()
+	reader := tar.NewReader(zipped)
+	texts := map[string]string{}
+	for {
+		header, err := reader.Next()
+		if errors.Is(err, io.EOF) {
+			return texts, nil
+		}
+		if err != nil {
+			return nil, err
+		}
+		if header.Typeflag != tar.TypeReg {
+			continue
+		}
+		text, err := io.ReadAll(reader)
+		if err != nil {
+			return nil, err
+		}
+		texts[header.Name] = string(text)
+	}
+}
+
+func orNone(digest string) string {
+	if digest == "" {
+		return "no digest"
+	}
+	return digest
+}

internal/builder/template_test.go

@@ -0,0 +1,136 @@
+package builder
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+)
+
+// A module's files kept as template files in its repository (novox/hq ADR 0349 §2, design 57 package T1, issue
+// 654): the build packs files/ into the module's templates archive and reads each template's text back from the
+// packed bytes into the file's content, so the manifest the mesh holds is the one it would hold for the text inline.
+
+const templatedModule = `{"module":"meshboard","version":"1",
+  "build":{"artifacts":[
+    {"name":"server","kind":"image","from":"Dockerfile"},
+    {"name":"files","kind":"archive","from":"files"}]},
+  "resources":[
+    {"id":"svc","type":"container","name":"meshboard","artifact":"server"},
+    {"id":"conf","type":"file","path":"/etc/meshboard/meshboard.conf","template":"files/meshboard.conf"},
+    {"id":"deeper","type":"file","path":"/etc/meshboard/deeper.conf","template":"files/a/deeper.conf"}]}`
+
+var templatedFiles = map[string]string{
+	"Dockerfile": "FROM scratch", "files/meshboard.conf": "listen = 8080\n\"quoted\" é\n",
+	"files/a/deeper.conf": "deeper\n", "files/unused.conf": "packed, named by nothing",
+}
+
+func contentOf(t *testing.T, m catalogue.Manifest, id string) string {
+	t.Helper()
+	for _, r := range m.Resources {
+		if r["id"] == id {
+			if _, has := r[catalogue.TemplateField]; has {
+				t.Fatalf("%s still names its template in the built manifest: %v", id, r)
+			}
+			text, ok := r["content"].(string)
+			if !ok {
+				t.Fatalf("%s carries no content: %v", id, r)
+			}
+			return text
+		}
+	}
+	t.Fatalf("no resource %s in %v", id, m.Resources)
+	return ""
+}
+
+func TestABuildReadsEachTemplateBackFromItsArchive(t *testing.T) {
+	r, workspace := aRepository(t, templatedModule, templatedFiles)
+	got, err := Build(context.Background(), r.run, r, "https://forge.invalid/meshboard.git", "", "", workspace, nil,
+		Npmrc{}, GitCredential{}, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if text := contentOf(t, got.Manifest, "conf"); text != templatedFiles["files/meshboard.conf"] {
+		t.Fatalf("the template's text is %q, not the file's", text)
+	}
+	if text := contentOf(t, got.Manifest, "deeper"); text != templatedFiles["files/a/deeper.conf"] {
+		t.Fatalf("the template's text is %q, not the file's", text)
+	}
+	if r.archives["meshboard/files"] == "" {
+		t.Fatalf("the templates archive was not published: %v", r.archives)
+	}
+	if problem := catalogue.HeldTemplateProblem(got.Manifest); problem != "" {
+		t.Fatal(problem)
+	}
+}
+
+func TestABuildWhoseTemplateIsMissingFailsNamingIt(t *testing.T) {
+	files := map[string]string{}
+	for k, v := range templatedFiles {
+		files[k] = v
+	}
+	delete(files, "files/a/deeper.conf")
+	r, workspace := aRepository(t, templatedModule, files)
+	_, err := Build(context.Background(), r.run, r, "https://forge.invalid/meshboard.git", "", "", workspace, nil,
+		Npmrc{}, GitCredential{}, nil)
+	if err == nil || !strings.Contains(err.Error(), "files/a/deeper.conf") {
+		t.Fatalf("a build whose template is missing did not fail naming it: %v", err)
+	}
+}
+
+// A walk that takes its check's build copies the archive by digest and builds nothing: the templates are read back
+// from the tree packed again, which is the archive only when it packs to the digest taken.
+func TestAWalkTakingAChecksBuildReadsTheTemplatesBackToo(t *testing.T) {
+	withVersion(t, "builder-1")
+	contents := map[string]string{"mod/" + ManifestName: templatedModule}
+	for k, v := range templatedFiles {
+		contents["mod/"+k] = v
+	}
+	scratch := newScratch()
+	r, run, workspace := aModuleWith(t, "tree-one", contents)
+	checked := aCheckBuiltBy(t, scratch, r, run, workspace)
+
+	r, run, workspace = aModuleWith(t, "tree-one", contents)
+	got, err := BuildReusing(t.Context(), run, r, Reuse{Scratch: scratch, Pulls: []PullRef{aPull}, Named: named(checked)},
+		"https://forge.invalid/meshboard.git", "mod", "main", workspace, nil, Npmrc{}, GitCredential{}, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got.Reused == nil || len(r.archives) > 0 {
+		t.Fatalf("the walk built again: reused %+v, why %q, published %v", got.Reused, got.Why, r.archives)
+	}
+	if text := contentOf(t, got.Manifest, "conf"); text != templatedFiles["files/meshboard.conf"] {
+		t.Fatalf("the template's text is %q, not the file's", text)
+	}
+}
+
+// The tree packed again must be the archive taken; text read from anything else is not the archive's.
+func TestTemplateTextsAreRefusedWhenTheTreeDoesNotPackToTheDigestTaken(t *testing.T) {
+	m, err := catalogue.ParseManifest([]byte(templatedModule))
+	if err != nil {
+		t.Fatal(err)
+	}
+	within := writeTree(t, t.TempDir(), templatedFiles)
+	built := []catalogue.Built{{Name: "files", Kind: catalogue.ArtifactArchive, Digest: "sha256:" + strings.Repeat("0", 64)}}
+	if _, err := withTemplateTexts(m, within, built); err == nil || !strings.Contains(err.Error(), "digest") {
+		t.Fatalf("text was read from a tree that does not pack to the archive taken: %v", err)
+	}
+}
+
+// writeTree writes files under dir and answers dir.
+func writeTree(t *testing.T, dir string, files map[string]string) string {
+	t.Helper()
+	for name, body := range files {
+		full := filepath.Join(dir, filepath.FromSlash(name))
+		if err := os.MkdirAll(filepath.Dir(full), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(full, []byte(body), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	return dir
+}

internal/catalogue/build.go

@@ -35,6 +35,10 @@ type Built struct {
 	// Launchers are, for a bundle in an interpreted language, the executable the build wrote beside
 	// each entrypoint, by entrypoint (novox/hq ADR 0193): what the node's runtime starts to serve it.
 	Launchers map[string]string
+	// Texts are, for the archive a module packs its templates into (TemplatesArtifact), each file's text as the
+	// build read it back from the packed archive, by its path inside it (novox/hq ADR 0349 §2). Never carried on
+	// the wire or kept: Resolve reads them into the files' content, which is what the mesh holds.
+	Texts map[string]string `json:"-"`
 }
 
 // Resolve fills a manifest's resources in from what was built.
@@ -71,6 +75,26 @@ func (m Manifest) Resolve(built []Built) (Manifest, error) {
 			m.Module, strings.Join(missing, " and "), oneOrOther(len(missing)))
 	}
 
+	// **Each template's text, as the build read it back from its templates archive** (novox/hq ADR 0349 §2): into
+	// the file's content, so what the mesh holds and composes is what the same text inline would be.
+	if m.Templated() {
+		name := TemplatesArtifact(m)
+		texts := by[name].Texts
+		if name == "" || texts == nil {
+			return Manifest{}, fmt.Errorf("%s names templates, and the build carried no text read back from the "+
+				"archive it packs %s/ into (%q): the builder that built it does not read templates",
+				m.Module, TemplatesDir, name)
+		}
+		filled, err := fillTemplates(m.Module, m.Resources, func(template string) (string, bool) {
+			t, ok := texts[strings.TrimPrefix(template, TemplatesDir+"/")]
+			return t, ok
+		}, fmt.Sprintf("the archive %q", name))
+		if err != nil {
+			return Manifest{}, err
+		}
+		m.Resources = filled
+	}
+
 	out := m
 	out.Build = nil
 	out.Resources = nil

internal/catalogue/manifest.go

@@ -1853,6 +1853,9 @@ func ParseManifest(raw []byte) (Manifest, error) {
 		}
 	}
 	problems = append(problems, m.Build.problems(m.Module)...)
+	// A file's text in a template file of the module's repository (novox/hq ADR 0349 §2): only a file, never beside
+	// content, only under files/, and packed by the module's build.
+	problems = append(problems, templateProblems(m)...)
 	problems = append(problems, undeliveredBundles(m)...)
 	// **What provides the artifact store cannot be delivered through it** (novox/hq 04-ISSUES/029).
 	//

internal/catalogue/template.go

@@ -0,0 +1,334 @@
+package catalogue
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+	"sort"
+	"strings"
+	"unicode/utf8"
+)
+
+// A file's text kept as a template file in its module's repository (novox/hq ADR 0349 §2, design 57 package T1,
+// issue 654).
+//
+// **Two forms, one composition.** A file resource says its text inline (`content`) or names a template file
+// beside its manifest (`"template": "files/<name>"`), never both. The module's build packs `files/` into an
+// archive artifact of its own — an `archive` artifact built `from: "files"` — and resolving the build reads each
+// template's text back from that packed archive into `content` and drops `template`. So the manifest the mesh
+// holds, composition and the node-engine are exactly as they were: a module with its text in `files/` composes
+// byte-identically to the same module with it inline. Where there is no build — `module check`, the merge gate,
+// `module add` — the text is read from the repository tree beside the manifest (WithTemplatesFrom).
+//
+// **Read back by the builder, carried in the resolved manifest.** The builder reads each template from the very
+// bytes it hashed into the archive's digest, so the text the mesh holds is the archive's. The controller
+// registers the resolved manifest as the build result carries it and fetches nothing from the artifact store; a
+// manifest that still names a template when it would be held — built by a builder that predates templates — is
+// refused at registration (HeldTemplateProblem).
+
+// TemplateField is the key a file resource names its template file by.
+const TemplateField = "template"
+
+// TemplatesDir is the module's directory its template files are kept in, and the directory its templates archive
+// is built from.
+const TemplatesDir = "files"
+
+// Templated is whether any of the manifest's resources names a template.
+func (m Manifest) Templated() bool {
+	for _, r := range m.Resources {
+		if _, has := r[TemplateField]; has {
+			return true
+		}
+	}
+	return false
+}
+
+// TemplatesArtifact is the name of the archive artifact the module packs its templates into — the one built from
+// files/ — or "" when it declares none, or more than one (both refused by templateProblems for a module naming a
+// template).
+func TemplatesArtifact(m Manifest) string {
+	found := templatesArtifacts(m)
+	if len(found) != 1 {
+		return ""
+	}
+	return found[0]
+}
+
+func templatesArtifacts(m Manifest) []string {
+	if m.Build == nil {
+		return nil
+	}
+	var found []string
+	for _, a := range m.Build.Artifacts {
+		if a.Kind == ArtifactArchive && a.URL == "" && cleanFrom(a.From) == TemplatesDir {
+			found = append(found, a.Name)
+		}
+	}
+	return found
+}
+
+// cleanFrom is an artifact's directory as one relative path: "./files/" is "files".
+func cleanFrom(from string) string {
+	c := path.Clean(strings.TrimSpace(from))
+	return strings.TrimPrefix(c, "./")
+}
+
+// templateOf is the template a resource names, whether it names one, and what is wrong with it ("" when nothing).
+func templateOf(module string, r map[string]any) (string, bool, string) {
+	raw, has := r[TemplateField]
+	if !has {
+		return "", false, ""
+	}
+	id := fmt.Sprint(r["id"])
+	if t := fmt.Sprint(r["type"]); t != "file" {
+		return "", true, fmt.Sprintf("%s: %s is a %s and names a template; only a file takes its text from one "+
+			"(novox/hq ADR 0349 §2)", module, id, t)
+	}
+	name, ok := raw.(string)
+	if !ok || strings.TrimSpace(name) == "" {
+		return "", true, fmt.Sprintf("%s: %s names a template that is not a path: %v; a template is %q",
+			module, id, raw, TemplatesDir+"/<name>")
+	}
+	if _, both := r["content"]; both {
+		return name, true, fmt.Sprintf("%s: %s names the template %q and says its content too; a file's text is "+
+			"in one place, the template or the content, never both (novox/hq ADR 0349 §2)", module, id, name)
+	}
+	if strings.HasPrefix(name, "/") || path.Clean(name) != name || !strings.HasPrefix(name, TemplatesDir+"/") ||
+		strings.Contains(name, "\\") {
+		return name, true, fmt.Sprintf("%s: %s names the template %q, which is not a file under %s/ of its own "+
+			"repository: a template is %q, a plain relative path, and the build packs only %s/",
+			module, id, name, TemplatesDir, TemplatesDir+"/<name>", TemplatesDir)
+	}
+	return name, true, ""
+}
+
+// templateProblems is what is wrong with the manifest's templates, as written: a template on something not a file,
+// beside content, outside files/, or a module naming templates whose build packs no archive from files/. Whether
+// each template exists is judged where a tree is (ReadTemplates) or the archive's text is (Resolve).
+func templateProblems(m Manifest) []string {
+	var problems []string
+	templated := false
+	for _, r := range m.Resources {
+		_, has, wrong := templateOf(m.Module, r)
+		templated = templated || has
+		if wrong != "" {
+			problems = append(problems, wrong)
+		}
+	}
+	if !templated {
+		return problems
+	}
+	switch found := templatesArtifacts(m); len(found) {
+	case 0:
+		problems = append(problems, fmt.Sprintf("%s names templates and its build packs no archive from %s/: "+
+			"declare an artifact {\"name\": \"files\", \"kind\": \"archive\", \"from\": %q} (novox/hq ADR 0349 §2)",
+			m.Module, TemplatesDir, TemplatesDir))
+	case 1:
+	default:
+		sort.Strings(found)
+		problems = append(problems, fmt.Sprintf("%s packs %s/ into %s; its templates are read from one archive",
+			m.Module, TemplatesDir, strings.Join(found, " and ")))
+	}
+	return problems
+}
+
+// fillTemplates is resources with each template's text as its content and the template key dropped: text says the
+// text of a template by its path ("files/<name>"), and whether it has one. A template it has no text for, or text
+// that is not UTF-8, is refused by name. Every resource is copied; the manifest's own are left as they were.
+func fillTemplates(module string, resources []map[string]any, text func(string) (string, bool),
+	where string) ([]map[string]any, error) {
+	out := make([]map[string]any, 0, len(resources))
+	var problems []string
+	for _, r := range resources {
+		name, has, wrong := templateOf(module, r)
+		if !has {
+			out = append(out, r)
+			continue
+		}
+		if wrong != "" {
+			problems = append(problems, wrong)
+			continue
+		}
+		body, ok := text(name)
+		if !ok {
+			problems = append(problems, fmt.Sprintf("%s: %v names the template %q, and %s holds no such file",
+				module, r["id"], name, where))
+			continue
+		}
+		if !utf8.ValidString(body) {
+			// A manifest is JSON: text that is not UTF-8 would be changed on the way, silently.
+			problems = append(problems, fmt.Sprintf("%s: %v names the template %q, which is not UTF-8 text; a "+
+				"file's text is carried as JSON and would not reach the machine as written", module, r["id"], name))
+			continue
+		}
+		filled := make(map[string]any, len(r))
+		for k, v := range r {
+			filled[k] = v
+		}
+		delete(filled, TemplateField)
+		filled["content"] = body
+		out = append(out, filled)
+	}
+	if len(problems) > 0 {
+		return nil, errors.New(strings.Join(problems, "; "))
+	}
+	return out, nil
+}
+
+// ReadTemplates is the text of each template the manifest names, read from the module's directory in a repository
+// tree, by template path. Refused by name: a template the directory lacks, and anything under files/ the build's
+// packing refuses — files/ itself, or any directory or file under it, that is a symlink or not a plain file — so
+// nothing judged here can be read from outside the tree, and no tree passes here that the build would refuse. Each
+// template is read through an os.Root of the module's directory besides, which no path element can leave.
+func ReadTemplates(m Manifest, dir string) (map[string]string, error) {
+	problems := templatesTreeProblems(m.Module, dir)
+	root, err := os.OpenRoot(dir)
+	if err != nil {
+		return nil, fmt.Errorf("%s: the module's directory cannot be opened to read its templates: %w", m.Module, err)
+	}
+	defer root.Close()
+	texts := map[string]string{}
+	for _, r := range m.Resources {
+		name, has, wrong := templateOf(m.Module, r)
+		if !has {
+			continue
+		}
+		if wrong != "" {
+			problems = append(problems, wrong)
+			continue
+		}
+		if _, read := texts[name]; read {
+			continue
+		}
+		info, err := root.Lstat(name)
+		switch {
+		case errors.Is(err, fs.ErrNotExist):
+			problems = append(problems, fmt.Sprintf("%s: %v names the template %q, and the module's directory "+
+				"has no such file", m.Module, r["id"], name))
+			continue
+		case err != nil:
+			problems = append(problems, fmt.Sprintf("%s: %v names the template %q, which cannot be read: %v",
+				m.Module, r["id"], name, err))
+			continue
+		case !info.Mode().IsRegular():
+			problems = append(problems, fmt.Sprintf("%s: %v names the template %q, which is not a plain file; "+
+				"the build packs only files", m.Module, r["id"], name))
+			continue
+		}
+		body, err := root.ReadFile(name)
+		if err != nil {
+			problems = append(problems, fmt.Sprintf("%s: %v names the template %q, which cannot be read: %v",
+				m.Module, r["id"], name, err))
+			continue
+		}
+		texts[name] = string(body)
+	}
+	if len(problems) > 0 {
+		return nil, errors.New(strings.Join(problems, "; "))
+	}
+	return texts, nil
+}
+
+// templatesTreeProblems is everything under the module's files/ that the build's packing refuses: files/ itself not
+// a plain directory, and any entry under it that is neither a directory nor a plain file — a symlink, to a file or a
+// directory, a device, a pipe. Each said by its path. A files/ that does not exist is no problem here: each template
+// it would have held is refused as missing.
+func templatesTreeProblems(module, dir string) []string {
+	top := filepath.Join(dir, TemplatesDir)
+	info, err := os.Lstat(top)
+	if errors.Is(err, fs.ErrNotExist) {
+		return nil
+	}
+	if err != nil {
+		return []string{fmt.Sprintf("%s: %s/ cannot be read: %v", module, TemplatesDir, err)}
+	}
+	if !info.IsDir() {
+		return []string{fmt.Sprintf("%s: %s/ is %s, not a directory of the module's own; its templates are read "+
+			"only from inside the repository, and the build packs only directories and files", module, TemplatesDir,
+			kindOf(info.Mode()))}
+	}
+	var problems []string
+	err = filepath.WalkDir(top, func(at string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() || d.Type().IsRegular() {
+			return nil
+		}
+		rel, _ := filepath.Rel(dir, at)
+		problems = append(problems, fmt.Sprintf("%s: %s is %s; the build packs only directories and files, so "+
+			"%s/ holds nothing else", module, filepath.ToSlash(rel), kindOf(d.Type()), TemplatesDir))
+		return nil
+	})
+	if err != nil {
+		problems = append(problems, fmt.Sprintf("%s: %s/ cannot be read: %v", module, TemplatesDir, err))
+	}
+	return problems
+}
+
+// kindOf says what a file that is not a plain file is.
+func kindOf(mode fs.FileMode) string {
+	switch {
+	case mode&fs.ModeSymlink != 0:
+		return "a symlink"
+	case mode&fs.ModeDevice != 0:
+		return "a device"
+	case mode&fs.ModeNamedPipe != 0:
+		return "a named pipe"
+	case mode&fs.ModeSocket != 0:
+		return "a socket"
+	case mode.IsDir():
+		return "a directory"
+	}
+	return "not a plain file"
+}
+
+// WithTemplatesFrom is the manifest with each template's text read from the module's directory in a repository
+// tree as its content: what `module check`, the merge gate and `module add` judge, where nothing was built. Read
+// again strictly afterwards, so every rule about a file's text judges the template's text exactly as it judges
+// inline content. A manifest naming no template is returned as it is.
+func WithTemplatesFrom(m Manifest, dir string) (Manifest, error) {
+	if !m.Templated() {
+		return m, nil
+	}
+	texts, err := ReadTemplates(m, dir)
+	if err != nil {
+		return Manifest{}, err
+	}
+	filled, err := fillTemplates(m.Module, m.Resources, func(name string) (string, bool) {
+		t, ok := texts[name]
+		return t, ok
+	}, "the module's directory")
+	if err != nil {
+		return Manifest{}, err
+	}
+	out := m
+	out.Resources = filled
+	raw, err := json.Marshal(out)
+	if err != nil {
+		return Manifest{}, err
+	}
+	return ParseManifest(raw)
+}
+
+// HeldTemplateProblem is why a manifest cannot be held by the mesh because it still names a template, or "": the
+// manifest the mesh holds carries every file's text, which a build reads back from its templates archive. One
+// naming a template was resolved by a builder that does not read templates, and would compose files with no text.
+func HeldTemplateProblem(m Manifest) string {
+	var named []string
+	for _, r := range m.Resources {
+		if t, has := r[TemplateField]; has {
+			named = append(named, fmt.Sprintf("%v (%v)", r["id"], t))
+		}
+	}
+	if len(named) == 0 {
+		return ""
+	}
+	return fmt.Sprintf("%s still names the template(s) of %s: the manifest the mesh holds carries each file's "+
+		"text, read back from the build's templates archive — this one was resolved by a builder that does not "+
+		"read templates, or not built at all (novox/hq ADR 0349 §2)", m.Module, strings.Join(named, ", "))
+}

internal/catalogue/template_test.go

@@ -0,0 +1,323 @@
+package catalogue
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// A file resource may name a template file in its module's repository (novox/hq ADR 0349 §2, design 57 package
+// T1, issue 654): the build packs files/ into an archive, and resolving the build reads each template's text back
+// into content, so the mesh holds, composes and sends exactly what it would for the same text inline.
+
+// The two forms of one module: its text inline, and its text in files/.
+const (
+	inlineTwin = `{"module":"tidy","version":"1",
+  "build":{"artifacts":[{"name":"files","kind":"archive","from":"files"}]},
+  "resources":[
+    {"id":"conf","type":"directory","path":"${dir:conf}"},
+    {"id":"main","type":"file","path":"${dir:conf}/tidy.conf","mode":"0644","content":"` + mainText + `"},
+    {"id":"extra","type":"file","path":"${dir:conf}/extra.conf","content":"` + extraText + `"}]}`
+	templatedTwin = `{"module":"tidy","version":"1",
+  "build":{"artifacts":[{"name":"files","kind":"archive","from":"files"}]},
+  "resources":[
+    {"id":"conf","type":"directory","path":"${dir:conf}"},
+    {"id":"main","type":"file","path":"${dir:conf}/tidy.conf","mode":"0644","template":"files/tidy.conf"},
+    {"id":"extra","type":"file","path":"${dir:conf}/extra.conf","template":"files/deeper/extra.conf"}]}`
+	mainText  = `# tidy\nroot = ${dir:conf}\nquoted = \"yes\" é\n`
+	extraText = `one\ntwo\n`
+)
+
+// templateTexts is what a build reads back from the packed files/ archive: by path inside it.
+func templateTexts(t *testing.T) map[string]string {
+	t.Helper()
+	var m struct{ Main, Extra string }
+	if err := json.Unmarshal([]byte(`{"Main":"`+mainText+`","Extra":"`+extraText+`"}`), &m); err != nil {
+		t.Fatal(err)
+	}
+	return map[string]string{"tidy.conf": m.Main, "deeper/extra.conf": m.Extra, "unused.conf": "not named"}
+}
+
+func builtFiles(texts map[string]string) []Built {
+	return []Built{{Name: "files", Kind: ArtifactArchive,
+		Reference: ArtifactStoreScheme + "tidy/files/blobs/sha256:" + strings.Repeat("c", 64),
+		Digest:    "sha256:" + strings.Repeat("c", 64), Texts: texts}}
+}
+
+// held is a manifest as registration holds it: resolved with what was built, then read again strictly.
+func held(t *testing.T, raw string, built []Built) Manifest {
+	t.Helper()
+	m, err := ParseManifest([]byte(raw))
+	if err != nil {
+		t.Fatal(err)
+	}
+	resolved, err := m.Resolve(built)
+	if err != nil {
+		t.Fatal(err)
+	}
+	again, err := json.Marshal(resolved)
+	if err != nil {
+		t.Fatal(err)
+	}
+	out, err := ParseManifest(again)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if problem := HeldTemplateProblem(out); problem != "" {
+		t.Fatal(problem)
+	}
+	return out
+}
+
+func composed(t *testing.T, m Manifest) string {
+	t.Helper()
+	got, err := Resolve(shelf(m), []string{m.Module}, workstation(), World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	out, err := json.Marshal(mustDeclare(t, got))
+	if err != nil {
+		t.Fatal(err)
+	}
+	return string(out)
+}
+
+func TestATemplatedModuleComposesByteIdenticallyToItsInlineTwin(t *testing.T) {
+	inline := composed(t, held(t, inlineTwin, builtFiles(nil)))
+	templated := composed(t, held(t, templatedTwin, builtFiles(templateTexts(t))))
+	if inline != templated {
+		t.Fatalf("the two forms compose differently:\ninline:    %s\ntemplated: %s", inline, templated)
+	}
+	if !strings.Contains(templated, "quoted = \\\"yes\\\"") || strings.Contains(templated, `"template"`) {
+		t.Fatalf("the composition does not carry the template's text as content: %s", templated)
+	}
+}
+
+// What `module check`, the merge gate and `module add` judge: the text read from the tree beside the manifest.
+func TestATemplatedModuleReadFromItsTreeComposesByteIdenticallyToItsInlineTwin(t *testing.T) {
+	dir := t.TempDir()
+	for name, text := range templateTexts(t) {
+		full := filepath.Join(dir, "files", filepath.FromSlash(name))
+		if err := os.MkdirAll(filepath.Dir(full), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(full, []byte(text), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	m, err := ParseManifest([]byte(templatedTwin))
+	if err != nil {
+		t.Fatal(err)
+	}
+	filled, err := WithTemplatesFrom(m, dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if filled.Templated() {
+		t.Fatal("a manifest read from its tree still names a template")
+	}
+	resolved, err := filled.Resolve(builtFiles(nil))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got, want := composed(t, resolved), composed(t, held(t, inlineTwin, builtFiles(nil))); got != want {
+		t.Fatalf("read from the tree, the module composes differently:\ninline:    %s\ntemplated: %s", want, got)
+	}
+}
+
+func TestAFileNamingBothATemplateAndContentIsRefused(t *testing.T) {
+	raw := strings.Replace(templatedTwin, `"template":"files/tidy.conf"`,
+		`"template":"files/tidy.conf","content":"x"`, 1)
+	_, err := ParseManifest([]byte(raw))
+	if err == nil || !strings.Contains(err.Error(), "main") || !strings.Contains(err.Error(), "never both") {
+		t.Fatalf("a file with both a template and content was not refused by name: %v", err)
+	}
+}
+
+func TestATemplateOutsideFilesIsRefusedByName(t *testing.T) {
+	for _, bad := range []string{"../tidy.conf", "/etc/tidy.conf", "files", "files/", "files/../tidy.conf",
+		"files/./tidy.conf", "other/tidy.conf", "tidy.conf", "files//tidy.conf", `files\\tidy.conf`} {
+		raw := strings.Replace(templatedTwin, `"files/tidy.conf"`, `"`+bad+`"`, 1)
+		_, err := ParseManifest([]byte(raw))
+		if err == nil || !strings.Contains(err.Error(), "main") || !strings.Contains(err.Error(), "not a file under files/") {
+			t.Errorf("the template %q was not refused by name: %v", bad, err)
+		}
+	}
+}
+
+func TestATemplateOnAResourceThatIsNotAFileIsRefused(t *testing.T) {
+	raw := strings.Replace(templatedTwin, `{"id":"conf","type":"directory","path":"${dir:conf}"}`,
+		`{"id":"conf","type":"directory","path":"${dir:conf}","template":"files/tidy.conf"}`, 1)
+	_, err := ParseManifest([]byte(raw))
+	if err == nil || !strings.Contains(err.Error(), "conf is a directory and names a template") {
+		t.Fatalf("a directory naming a template was not refused: %v", err)
+	}
+}
+
+func TestATemplatedModuleWhoseBuildPacksNoFilesIsRefused(t *testing.T) {
+	for _, build := range []string{
+		``,
+		`"build":{"artifacts":[{"name":"look","kind":"archive","from":"theme"}]},`,
+		`"build":{"artifacts":[{"name":"a","kind":"archive","from":"files"},{"name":"b","kind":"archive","from":"./files/"}]},`,
+	} {
+		raw := strings.Replace(templatedTwin,
+			`"build":{"artifacts":[{"name":"files","kind":"archive","from":"files"}]},`, build, 1)
+		_, err := ParseManifest([]byte(raw))
+		if err == nil || !strings.Contains(err.Error(), "files/") {
+			t.Errorf("a templated module with the build %q was not refused: %v", build, err)
+		}
+	}
+}
+
+func TestAMissingTemplateIsRefusedByName(t *testing.T) {
+	m, err := ParseManifest([]byte(templatedTwin))
+	if err != nil {
+		t.Fatal(err)
+	}
+	// In the tree beside the manifest.
+	dir := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(dir, "files"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "files", "tidy.conf"), []byte("x"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	_, err = WithTemplatesFrom(m, dir)
+	if err == nil || !strings.Contains(err.Error(), "extra") || !strings.Contains(err.Error(), "files/deeper/extra.conf") {
+		t.Fatalf("a template missing from the tree was not refused by name: %v", err)
+	}
+	// And in what the build read back from its archive.
+	texts := templateTexts(t)
+	delete(texts, "deeper/extra.conf")
+	_, err = m.Resolve(builtFiles(texts))
+	if err == nil || !strings.Contains(err.Error(), "extra") || !strings.Contains(err.Error(), "files/deeper/extra.conf") {
+		t.Fatalf("a template missing from the archive was not refused by name: %v", err)
+	}
+}
+
+func TestATemplateThatIsASymlinkIsRefused(t *testing.T) {
+	m, err := ParseManifest([]byte(templatedTwin))
+	if err != nil {
+		t.Fatal(err)
+	}
+	dir := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(dir, "files", "deeper"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "elsewhere"), []byte("x"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "files", "tidy.conf"), []byte("x"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink(filepath.Join(dir, "elsewhere"), filepath.Join(dir, "files", "deeper", "extra.conf")); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := WithTemplatesFrom(m, dir); err == nil || !strings.Contains(err.Error(), "not a plain file") {
+		t.Fatalf("a template that is a symlink was not refused: %v", err)
+	}
+}
+
+func TestAResolveWithoutTheArchivesTextIsRefused(t *testing.T) {
+	m, err := ParseManifest([]byte(templatedTwin))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := m.Resolve(builtFiles(nil)); err == nil || !strings.Contains(err.Error(), "files") {
+		t.Fatalf("a templated module resolved with no text read back from its archive: %v", err)
+	}
+}
+
+func TestATemplateThatIsNotUTF8IsRefused(t *testing.T) {
+	m, err := ParseManifest([]byte(templatedTwin))
+	if err != nil {
+		t.Fatal(err)
+	}
+	texts := templateTexts(t)
+	texts["tidy.conf"] = "\xff\xfe"
+	if _, err := m.Resolve(builtFiles(texts)); err == nil || !strings.Contains(err.Error(), "UTF-8") {
+		t.Fatalf("a template that is not UTF-8 was resolved: %v", err)
+	}
+}
+
+// What registration refuses: a manifest to be held that still names a template — one resolved by a builder that
+// predates templates would otherwise compose files with no text.
+func TestAManifestStillNamingATemplateIsNotHeld(t *testing.T) {
+	m, err := ParseManifest([]byte(templatedTwin))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if problem := HeldTemplateProblem(m); !strings.Contains(problem, "main") || !strings.Contains(problem, "files/tidy.conf") {
+		t.Fatalf("a manifest naming a template would be held: %q", problem)
+	}
+	if problem := HeldTemplateProblem(held(t, inlineTwin, builtFiles(nil))); problem != "" {
+		t.Fatalf("an inline manifest is refused: %s", problem)
+	}
+}
+
+// A symlinked files/, or a symlinked directory under it, would read a file outside the tree: refused by name,
+// as is any symlink or special file under files/ that no template names, which the build's packing refuses.
+func TestASymlinkAnywhereUnderFilesIsRefusedByName(t *testing.T) {
+	m, err := ParseManifest([]byte(templatedTwin))
+	if err != nil {
+		t.Fatal(err)
+	}
+	outside := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(outside, "deeper"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	for _, name := range []string{"tidy.conf", "deeper/extra.conf", "secret"} {
+		if err := os.WriteFile(filepath.Join(outside, filepath.FromSlash(name)), []byte("outside"), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	write := func(t *testing.T, dir, name string) {
+		t.Helper()
+		full := filepath.Join(dir, filepath.FromSlash(name))
+		if err := os.MkdirAll(filepath.Dir(full), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(full, []byte("inside"), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	link := func(t *testing.T, target, at string) {
+		t.Helper()
+		if err := os.MkdirAll(filepath.Dir(at), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.Symlink(target, at); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, c := range []struct {
+		name  string
+		make  func(t *testing.T, dir string)
+		names string
+	}{
+		{"files/ itself", func(t *testing.T, dir string) {
+			link(t, outside, filepath.Join(dir, "files"))
+		}, "files/ is a symlink"},
+		{"a directory under files/", func(t *testing.T, dir string) {
+			write(t, dir, "files/tidy.conf")
+			link(t, filepath.Join(outside, "deeper"), filepath.Join(dir, "files", "deeper"))
+		}, "files/deeper is a symlink"},
+		{"a file no template names", func(t *testing.T, dir string) {
+			write(t, dir, "files/tidy.conf")
+			write(t, dir, "files/deeper/extra.conf")
+			link(t, filepath.Join(outside, "secret"), filepath.Join(dir, "files", "unnamed"))
+		}, "files/unnamed is a symlink"},
+	} {
+		dir := t.TempDir()
+		c.make(t, dir)
+		_, err := WithTemplatesFrom(m, dir)
+		if err == nil || !strings.Contains(err.Error(), c.names) {
+			t.Errorf("a symlinked %s was not refused by name: %v", c.name, err)
+		}
+		if err != nil && strings.Contains(err.Error(), "outside") {
+			t.Errorf("a symlinked %s was read: %v", c.name, err)
+		}
+	}
+}

internal/inventory/catalogue.go

@@ -117,6 +117,11 @@ func (i *Inventory) RegisterModule(ctx context.Context, m catalogue.Manifest, fr
 			}
 		}
 	}
+	// **The manifest the mesh holds carries each file's text** (novox/hq ADR 0349 §2): one still naming a template
+	// would compose a file with no text, so it is refused by name — a build by a builder that predates templates.
+	if why := catalogue.HeldTemplateProblem(m); why != "" {
+		return fmt.Errorf("%s is not registered: %s", m.Module, why)
+	}
 	raw, err := json.Marshal(m)
 	if err != nil {
 		return err

internal/inventory/template_test.go

@@ -0,0 +1,25 @@
+package inventory
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+)
+
+// The manifest the mesh holds carries each file's text (novox/hq ADR 0349 §2): one still naming a template — a
+// build by a builder that predates templates, or a manifest handed over unbuilt — would compose a file with no
+// text, and is refused by name.
+func TestAManifestStillNamingATemplateIsNotRegistered(t *testing.T) {
+	inv := ForTest(t)
+	m := catalogue.Manifest{Module: "notifier", Version: "1", Resources: []map[string]any{
+		{"id": "conf", "type": "file", "path": "/etc/notifier.conf", "template": "files/notifier.conf"}}}
+	err := inv.RegisterModule(t.Context(), m, Source{})
+	if err == nil || !strings.Contains(err.Error(), "files/notifier.conf") {
+		t.Fatalf("a manifest naming a template was registered: %v", err)
+	}
+	m.Resources[0] = map[string]any{"id": "conf", "type": "file", "path": "/etc/notifier.conf", "content": "x"}
+	if err := inv.RegisterModule(t.Context(), m, Source{}); err != nil {
+		t.Fatalf("the same manifest with its text was refused: %v", err)
+	}
+}