mesh-build-go asks a run's input of the seat verb the ask names, and reads no checker state (issue 1921, B0 review round 1)

The operator's answer: reading mesh-delivery-checker.inputs broke ADR 0596 §2. The manifest drops that read and invokes
seat:mesh-delivery-checker.input; the run step asks the verb through the runtime (stdio.Ask) and takes only the bytes
the ask names (delivery.RunInput.Read).

Claude-Session: https://claude.ai/code/session_01NcbgfFSnn24M3GcqttoU7i

modules/mesh-build-go/README.md

@@ -49,6 +49,10 @@ already gone is no error, one a running step holds is refused); its caller calls
 failed fetch removes its own workspace. A workspace no caller released is removed two hours after its last use (ADR
 0509), and the removal is said in the log as the caller's fault.
 
+The programs this module builds from a commit and keeps in its cache (composers of compose asks, checking programs of run
+asks) are read by `build_go_kept` (kind, key, size, last use) and removed by `build_go_kept_drop {kind, key}`; one no ask used
+for 30 days is swept with the workspaces (issue 1921).
+
 A pin on a pull request's head (issue 1148): when `go mod download` fails on a `git.novox.be/novox/*` pseudo-version, the
 fetch looks for that commit among the forge's `refs/pull/*/head`, places the repository at it under the workspace's
 `pinned/beside/` as a plain directory, and hands it to Go (the fetch's commands, and the build with `GOPROXY=off`) through a

modules/mesh-build-go/buildstep/isolate.go

@@ -27,16 +27,19 @@ const Bubblewrap = "bwrap"
 //   - the system's programs and libraries read-only, and of /etc only what a program needs to run (users, libraries,
 //     certificates, time zone), with a hosts file naming only the loopback;
 //   - the Workspace and Writable directories read-write, the ReadOnly ones (the toolchain, the modules the fetch step
-//     downloaded) read-only;
+//     downloaded) read-only, and the ReadOnlyInside ones (inside the Workspace) read-only over it;
 //   - the shared warm Caches read-only under a throwaway writable layer (S18), or read-write for a trunk build alone
 //     (WriteCaches), so a candidate's code never changes what a later build reads.
 type Isolation struct {
-	Workspace   string
-	Writable    []string
-	ReadOnly    []string
-	Caches      []string
-	WriteCaches bool
-	Env         []string
+	Workspace string
+	Writable  []string
+	ReadOnly  []string
+	// ReadOnlyInside are directories inside the Workspace or a Writable one bound read-only after them, so they stay
+	// read-only (a later bind of a path wins; a ReadOnly one inside the Workspace would be covered by it).
+	ReadOnlyInside []string
+	Caches         []string
+	WriteCaches    bool
+	Env            []string
 	// Hosts is the file bound as /etc/hosts; Isolated writes one naming only the loopback.
 	Hosts string
 }
@@ -91,7 +94,7 @@ func (iso Isolation) command(env []string, name string, args ...string) ([]strin
 	for _, group := range []struct {
 		what string
 		dirs []string
-	}{{"writable directory", iso.Writable}, {"read-only directory", iso.ReadOnly}, {"cache", iso.Caches}} {
+	}{{"writable directory", iso.Writable}, {"read-only directory", iso.ReadOnly}, {"read-only directory", iso.ReadOnlyInside}, {"cache", iso.Caches}} {
 		for _, d := range group.dirs {
 			if err := checkDir(group.what, d); err != nil {
 				return nil, err
@@ -118,6 +121,9 @@ func (iso Isolation) command(env []string, name string, args ...string) ([]strin
 	for _, d := range iso.Writable {
 		argv = append(argv, "--bind", d, d)
 	}
+	for _, d := range iso.ReadOnlyInside {
+		argv = append(argv, "--ro-bind", d, d)
+	}
 	if iso.Hosts != "" {
 		argv = append(argv, "--ro-bind", iso.Hosts, "/etc/hosts")
 	}

modules/mesh-build-go/buildstep/pull.go

@@ -561,6 +561,36 @@ func (p *Puller) declineRun(msg *Pulled, ask delivery.StepAsk, key string, step
 	p.mu.Unlock()
 }
 
+// refuseUnread ends an ask this module cannot read: when its data holds an id that keys a step, the step is written
+// refused with the reason, so the asker learns at once that no node began it; otherwise (no id, not JSON) the ask is only
+// dropped and logged. The message is dropped either way.
+func (p *Puller) refuseUnread(msg *Pulled, why error) {
+	var probe struct {
+		ID   string `json:"id"`
+		Kind string `json:"kind"`
+	}
+	if json.Unmarshal(msg.Data, &probe) == nil && probe.ID != "" {
+		if key, kerr := delivery.AskStepKey(p.Node, probe.ID); kerr == nil {
+			tool := "ask"
+			if probe.Kind != "" {
+				tool = probe.Kind + " ask"
+			}
+			at := now().UTC()
+			step := delivery.Step{ID: probe.ID, Tool: tool, Node: p.Node, State: delivery.StepRefused, Started: at, Ended: at,
+				Reason: fmt.Sprintf("this build module on %s cannot read the ask: %v", p.Node, why), Owner: sdkstep.Owner}
+			if werr := writeEnd(p.Put, key, step); werr != nil {
+				p.logf("the unread ask %s cannot be answered on %s: %v", probe.ID, p.Node, werr)
+			} else {
+				p.logf("an ask refused: %v", why)
+				_ = msg.Term()
+				return
+			}
+		}
+	}
+	p.logf("an ask dropped: %v", why)
+	_ = msg.Term()
+}
+
 func withKind(msg *Pulled, kind string) *Pulled {
 	if msg != nil {
 		msg.Kind = kind
@@ -576,9 +606,10 @@ func (p *Puller) take(ctx context.Context, msg *Pulled) {
 		err = fmt.Errorf("the ask %s is a %s ask of %s, pulled from the %s %s worker", ask.ID, ask.Kind, ask.Language, p.Language, kind)
 	}
 	if err != nil {
-		// An ask that is not one runs nowhere: delivering it again would only fail again.
-		p.logf("an ask dropped: %v", err)
-		_ = msg.Term()
+		// An ask that is not one runs nowhere: delivering it again would only fail again. But an ask that names an id
+		// is answered on its step key as refused, naming why (a job this build module does not know, a version it does
+		// not read): a dropped ask must always be answered, or its asker waits to its bound for nothing.
+		p.refuseUnread(msg, err)
 		return
 	}
 	if lacks := delivery.Lacks(ask.Needs, p.Has); len(lacks) > 0 {

modules/mesh-build-go/buildstep/pull_test.go

@@ -519,3 +519,39 @@ func TestAPoisonedAskIsSaidAndRunNoMore(t *testing.T) {
 		t.Errorf("acked %v naked %v, want it termed alone", acked, naked)
 	}
 }
+
+// An ask whose job this build module does not know is answered on its step key as refused, naming why, never only dropped
+// (a dropped ask leaves its asker waiting to its bound); one with no id is still dropped.
+func TestPullAnswersAnAskItCannotRead(t *testing.T) {
+	src, st := NewFakeAsks(), newSteps()
+	good := testAsk(delivery.AskCheck)
+	raw, err := delivery.EncodeStepAsk(good)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m map[string]any
+	_ = json.Unmarshal(raw, &m)
+	delete(m, "check")
+	m["frobnicate"] = map[string]any{"program": "x"}
+	odd, _ := json.Marshal(m)
+	// The job is not one this reader holds, so the ask carries none it knows: decode refuses it.
+	if _, err := delivery.DecodeStepAsk(odd); err == nil {
+		t.Fatal("the fixture ask decodes")
+	}
+	src.Publish(delivery.AskCheck, odd)
+	src.Publish(delivery.AskCheck, []byte(`{"v":1}`))
+	p := &Puller{Source: src, Language: delivery.AskGo, Node: "ace", Put: st.put, Capacity: func() int { return 1 },
+		PullWait: 10 * time.Millisecond, Run: func(ctx context.Context, a delivery.StepAsk) (any, error) {
+			t.Error("an unread ask ran")
+			return nil, nil
+		}}
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	go p.Pull(ctx)
+	waitFor(t, "both termed", func() bool { _, tm, _ := src.Fates(); return len(tm) == 2 })
+	key, _ := delivery.AskStepKey("ace", good.ID)
+	s, ok := st.get(key)
+	if !ok || s.State != delivery.StepRefused || !strings.Contains(s.Reason, "cannot read the ask") || !strings.Contains(s.Reason, "exactly one") {
+		t.Fatalf("the unread ask's step = %+v (%v)", s, ok)
+	}
+}

modules/mesh-build-go/buildstep/trees.go

@@ -82,18 +82,20 @@ func narrow(ctx context.Context, run forgekey.Runner, env []string, dir, commit,
 	for i, p := range paths {
 		full[i] = path.Join(mdir, p)
 	}
-	r := run(ctx, env, "git", append([]string{"-C", dir, "ls-tree", "-z", commit, "--"}, full...)...)
-	if r.Status != 0 || r.Err != "" {
-		return fmt.Errorf("git ls-tree %s of the module %s: %s", commit, mdir, forgekey.Said(r.Err+"\n"+r.Stderr))
-	}
 	objects := map[string]string{}
-	for _, l := range strings.Split(r.Stdout, "\x00") {
-		meta, name, ok := strings.Cut(l, "\t")
-		fields := strings.Fields(meta)
-		if !ok || len(fields) != 3 {
-			continue
+	for _, round := range unnested(full) {
+		r := run(ctx, env, "git", append([]string{"-C", dir, "ls-tree", "-z", commit, "--"}, round...)...)
+		if r.Status != 0 || r.Err != "" {
+			return fmt.Errorf("git ls-tree %s of the module %s: %s", commit, mdir, forgekey.Said(r.Err+"\n"+r.Stderr))
+		}
+		for _, l := range strings.Split(r.Stdout, "\x00") {
+			meta, name, ok := strings.Cut(l, "\t")
+			fields := strings.Fields(meta)
+			if !ok || len(fields) != 3 {
+				continue
+			}
+			objects[name] = fields[2]
 		}
-		objects[name] = fields[2]
 	}
 	mt.Paths = map[string]string{}
 	for i, p := range paths {
@@ -106,4 +108,35 @@ func narrow(ctx context.Context, run forgekey.Runner, env []string, dir, commit,
 	return nil
 }
 
+// unnested splits paths into rounds of one git ls-tree each, none of whose paths lies inside another of its round: given
+// "go" and "go/seats/x" together, git ls-tree descends into go and lists its children instead of go itself, so the
+// object of go is missing from its answer (issue 1966: mesh-contracts' manifest names both). Usually one round; the
+// order of paths is kept within a round.
+func unnested(paths []string) [][]string {
+	var rounds [][]string
+	for _, p := range paths {
+		placed := false
+		for i, round := range rounds {
+			if !nestsWithAny(p, round) {
+				rounds[i] = append(round, p)
+				placed = true
+				break
+			}
+		}
+		if !placed {
+			rounds = append(rounds, []string{p})
+		}
+	}
+	return rounds
+}
+
+func nestsWithAny(p string, round []string) bool {
+	for _, q := range round {
+		if p == q || strings.HasPrefix(p, q+"/") || strings.HasPrefix(q, p+"/") || p == "." || q == "." {
+			return true
+		}
+	}
+	return false
+}
+
 func sha256Hex(b []byte) string { h := sha256.Sum256(b); return hex.EncodeToString(h[:]) }

modules/mesh-build-go/buildstep/trees_integration_test.go

@@ -62,4 +62,16 @@ func TestAGoOnlyCommitLeavesTheNamedObjectsEqualOnRealGit(t *testing.T) {
 	if src["."].Paths["src"] != realGit(t, repo, "rev-parse", "HEAD:src") {
 		t.Fatalf("the object of src is %s, git says %s", src["."].Paths["src"], realGit(t, repo, "rev-parse", "HEAD:src"))
 	}
+
+	// A manifest naming a path and a path inside it (mesh-contracts' "go" and "go/seats/meshvault"; issue 1966): each
+	// gets its own object, not git ls-tree's listing of the outer one's children.
+	writeFile(t, repo, "nested/module.json", `{"module":"nested","version":"1","build":{"artifacts":[`+
+		`{"name":"go","kind":"package","language":"go","paths":["go"]},`+
+		`{"name":"go-seat","kind":"package","language":"go","paths":["go/seats/a"]}]}}`)
+	writeFile(t, repo, "nested/go/go.mod", "module x\n")
+	writeFile(t, repo, "nested/go/seats/a/a.go", "package a\n")
+	nested := trees(commit("nested"))["nested"]
+	if nested.Paths["go"] != realGit(t, repo, "rev-parse", "HEAD:nested/go") || nested.Paths["go/seats/a"] != realGit(t, repo, "rev-parse", "HEAD:nested/go/seats/a") {
+		t.Fatalf("a path and a path inside it: %v", nested.Paths)
+	}
 }

modules/mesh-build-go/cmd/mesh-build-go/asks.go

@@ -121,6 +121,9 @@ func (m *Module) Puller(steps []StepTool, source buildstep.AskSource) *buildstep
 			if a.Compose != nil {
 				return m.compose(ctx, ask.Fetch, a)
 			}
+			if a.Run != nil {
+				return m.run(ctx, ask.Fetch, a)
+			}
 			return buildstep.RunAsk(ctx, ask, a)
 		}}
 }

modules/mesh-build-go/cmd/mesh-build-go/candidate.go

@@ -97,9 +97,10 @@ func (m *Module) candidate(ctx context.Context, workspace string) (string, error
 // compileError is the first line of the compiler's output that says an error: not the `# package` heading go build
 // prints above a package's errors, nor Go's progress.
 func compileError(out string) string {
-	for _, l := range strings.Split(out, "\n") {
+	lines := strings.Split(out, "\n")
+	for i, l := range lines {
 		if l = strings.TrimSpace(l); l != "" && !strings.HasPrefix(l, "#") && !strings.HasPrefix(l, "go: downloading ") {
-			return l
+			return withContinuation(l, lines[i+1:])
 		}
 	}
 	return firstLine(out)

modules/mesh-build-go/cmd/mesh-build-go/compose.go

@@ -38,7 +38,7 @@ var composerLocks sync.Map
 
 // composerPath is where the composer of key is kept: the cache directory, beside Go's own caches.
 func (m *Module) composerPath(key string) string {
-	return filepath.Join(m.Cache, "composers", key, "mesh-compose")
+	return m.programPath("composers", key)
 }
 
 // compose runs a compose ask: the composer of its commit, built once, over its request with the manifests filled.
@@ -50,7 +50,11 @@ func (m *Module) compose(ctx context.Context, fetch buildstep.StepFunc, a delive
 	if err != nil {
 		return nil, err
 	}
-	key := delivery.ComposerKey(repository, commit, job.Dir, job.Package, delivery.ToolchainUsed{Version: installed, Recipe: m.Recipe.Version()})
+	versions, err := sdkstep.PackagesArg(job.Fetch["packages"])
+	if err != nil {
+		return nil, buildstep.Refuse("the compose ask %s: %v", a.ID, err)
+	}
+	key := delivery.ComposerKey(repository, commit, job.Dir, job.Package, delivery.ToolchainUsed{Version: installed, Recipe: m.Recipe.Version()}, versions)
 	exe, built, err := m.composerOf(ctx, fetch, job, key)
 	if err != nil {
 		return nil, err
@@ -94,17 +98,25 @@ func (m *Module) manifestOf(digest string) ([]byte, error) {
 
 // composerOf is the composer kept under key, or, when none is, the one built now from the fetched commit (built true).
 func (m *Module) composerOf(ctx context.Context, fetch buildstep.StepFunc, job delivery.ComposeJob, key string) (string, bool, error) {
-	exe := m.composerPath(key)
-	mu, _ := composerLocks.LoadOrStore(exe, &sync.Mutex{})
-	mu.(*sync.Mutex).Lock()
-	defer mu.(*sync.Mutex).Unlock()
+	return m.programOf(ctx, fetch, "composers", "composer", key, job.Fetch, job.Dir, job.Package)
+}
+
+// programOf is the program kept under key in the cache directory kind, or, when none is, the one built now: the commit
+// fetch names is fetched (the fetch step: the forge key and the network, none of the change's code), and package in the
+// Go module of dir is built in a run step shut off with nothing fetched. what names it in a failure.
+func (m *Module) programOf(ctx context.Context, fetch buildstep.StepFunc, kind, what, key string, fetchArgs map[string]any, dir, pkg string) (string, bool, error) {
+	exe := m.programPath(kind, key)
+	mu := lockOf(exe)
+	mu.Lock()
+	defer mu.Unlock()
 	if st, err := os.Stat(exe); err == nil && st.Mode().IsRegular() {
+		touch(exe, m.clock())
 		return exe, false, nil
 	}
 	if fetch == nil {
 		return "", false, buildstep.Refuse("this build module fetches nothing")
 	}
-	out, err := fetch(ctx, job.Fetch)
+	out, err := fetch(ctx, fetchArgs)
 	if err != nil {
 		return "", false, err
 	}
@@ -121,11 +133,11 @@ func (m *Module) composerOf(ctx context.Context, fetch buildstep.StepFunc, job d
 	defer m.releaseSaid(f.Workspace)
 	done := m.spaces().Hold(f.Workspace)
 	defer done()
-	dir := filepath.Join(m.Work, f.Workspace, "tree", job.Dir)
-	if _, err := os.Stat(filepath.Join(dir, "go.mod")); err != nil {
-		return "", false, fmt.Errorf("%s at %s holds no go.mod in %s, so no composer can be built there", job.Fetch["repository"], job.Fetch["commit"], job.Dir)
+	tree := filepath.Join(m.Work, f.Workspace, "tree", dir)
+	if _, err := os.Stat(filepath.Join(tree, "go.mod")); err != nil {
+		return "", false, fmt.Errorf("%s at %s holds no go.mod in %s, so no %s can be built there", fetchArgs["repository"], fetchArgs["commit"], dir, what)
 	}
-	into := filepath.Join(m.Work, f.Workspace, "composer", "mesh-compose")
+	into := filepath.Join(m.Work, f.Workspace, what, "built")
 	if err := os.MkdirAll(filepath.Dir(into), 0o700); err != nil {
 		return "", false, err
 	}
@@ -133,15 +145,15 @@ func (m *Module) composerOf(ctx context.Context, fetch buildstep.StepFunc, job d
 	if err != nil {
 		return "", false, err
 	}
-	env := append(m.goEnvFor(dir), "GOPROXY=off", "GOTOOLCHAIN=local", "CGO_ENABLED=0")
-	r := run(ctx, env, "go", "-C", dir, "build", "-trimpath", "-o", into, job.Package)
+	env := append(m.goEnvFor(tree), "GOPROXY=off", "GOTOOLCHAIN=local", "CGO_ENABLED=0")
+	r := run(ctx, env, "go", "-C", tree, "build", "-trimpath", "-o", into, pkg)
 	if r.Status != 0 || r.Err != "" {
 		// The words Go says when the module holds no such package (a mesh-sdk from before the composer) are kept whole,
 		// so the asker tells that apart from a fault.
-		return "", false, fmt.Errorf("the composer %s does not build at %s: %s", job.Package, job.Fetch["commit"], compileError(r.Err+"\n"+r.Stderr+"\n"+r.Stdout))
+		return "", false, fmt.Errorf("the %s %s does not build at %s: %s", what, pkg, fetchArgs["commit"], compileError(r.Err+"\n"+r.Stderr+"\n"+r.Stdout))
 	}
 	if err := copyExecutable(into, exe); err != nil {
-		return "", false, fmt.Errorf("the composer could not be kept: %w", err)
+		return "", false, fmt.Errorf("the %s could not be kept: %w", what, err)
 	}
 	return exe, true, nil
 }

modules/mesh-build-go/cmd/mesh-build-go/compose_test.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"os"
 	"path/filepath"
 	"slices"
@@ -64,7 +65,7 @@ func TestAKeptComposerIsRunWithTheManifestsFilled(t *testing.T) {
 	read, digests := indexerHolds(t, `{"module":"demo","version":"1"}`)
 	m.ReadManifest = read
 	a := composeAskOf(t, digests[0])
-	key := delivery.ComposerKey("novox/mesh-sdk", composeCommit, "go", composer.Package, delivery.ToolchainUsed{Version: "go1.26.0", Recipe: m.Recipe.Version()})
+	key := delivery.ComposerKey("novox/mesh-sdk", composeCommit, "go", composer.Package, delivery.ToolchainUsed{Version: "go1.26.0", Recipe: m.Recipe.Version()}, nil)
 	exe := m.composerPath(key)
 	if err := os.MkdirAll(filepath.Dir(exe), 0o700); err != nil {
 		t.Fatal(err)
@@ -95,13 +96,40 @@ func TestAKeptComposerIsRunWithTheManifestsFilled(t *testing.T) {
 	}
 }
 
+// 1921: the versions an ask names are an input of the composer it builds, so a composer kept for one set is not run for
+// another; an ask naming none keeps the key it always had.
+func TestAComposerIsKeptPerAskedVersions(t *testing.T) {
+	m := composeModule(t)
+	m.ReadManifest, _ = indexerHolds(t)
+	a := composeAskOf(t, "feedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeed")
+	tc := delivery.ToolchainUsed{Version: "go1.26.0", Recipe: m.Recipe.Version()}
+	plain := delivery.ComposerKey("novox/mesh-sdk", composeCommit, "go", composer.Package, tc, nil)
+	a.Compose.Fetch["packages"] = map[string]any{"git.novox.be/novox/mesh-sdk/go": strings.Repeat("3", 40)}
+	named := delivery.ComposerKey("novox/mesh-sdk", composeCommit, "go", composer.Package, tc, delivery.PackageVersions{"git.novox.be/novox/mesh-sdk/go": strings.Repeat("3", 40)})
+	if plain == named {
+		t.Fatal("the key ignores the versions")
+	}
+	// A composer kept under the key without versions is not used for the ask that names some: it is fetched.
+	os.MkdirAll(filepath.Dir(m.composerPath(plain)), 0o700)
+	os.WriteFile(m.composerPath(plain), []byte("#!/bin/sh\nexit 0\n"), 0o700)
+	fetched := false
+	fetch := func(context.Context, map[string]any) (any, error) {
+		fetched = true
+		return nil, errors.New("stop")
+	}
+	m.compose(context.Background(), fetch, a)
+	if !fetched {
+		t.Error("a composer built for no versions was run for an ask naming some")
+	}
+}
+
 // 1622: a manifest the indexer does not keep fails the ask, naming its digest; a fetched commit with no go.mod where
 // the ask builds fails it naming the directory, and its workspace is released.
 func TestAComposeAskFailsLoudly(t *testing.T) {
 	m := composeModule(t)
 	m.ReadManifest, _ = indexerHolds(t)
 	a := composeAskOf(t, "feedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeedfeed")
-	key := delivery.ComposerKey("novox/mesh-sdk", composeCommit, "go", composer.Package, delivery.ToolchainUsed{Version: "go1.26.0", Recipe: m.Recipe.Version()})
+	key := delivery.ComposerKey("novox/mesh-sdk", composeCommit, "go", composer.Package, delivery.ToolchainUsed{Version: "go1.26.0", Recipe: m.Recipe.Version()}, nil)
 	os.MkdirAll(filepath.Dir(m.composerPath(key)), 0o700)
 	os.WriteFile(m.composerPath(key), []byte("#!/bin/sh\nexit 0\n"), 0o700)
 	if _, err := m.compose(context.Background(), nil, a); err == nil || !strings.Contains(err.Error(), "feedfeed") {
@@ -122,11 +150,17 @@ func TestAComposeAskFailsLoudly(t *testing.T) {
 	}
 }
 
-// 1622: the module reads the delivery indexer's manifests, which a compose ask names by digest.
+// 1622: the module reads the delivery indexer's manifests, which a compose ask names by digest. 1921 (B0): a run's input
+// is asked of the checker seat's verb input, as the manifest invokes it, and no state of the checker's inputs is read
+// (ADR 0596 §2).
 func TestTheModuleReadsTheIndexersManifests(t *testing.T) {
-	if m := readManifest(t); !slices.Contains(m.Reads, ManifestsState) {
+	m := readManifest(t)
+	if !slices.Contains(m.Reads, ManifestsState) {
 		t.Errorf("reads = %v, lacks %s", m.Reads, ManifestsState)
 	}
+	if !slices.Contains(m.Invokes, runInputVerb) || slices.Contains(m.Reads, "mesh-delivery-checker.inputs") {
+		t.Errorf("invokes = %v, reads = %v: want %s invoked and no inputs state read", m.Invokes, m.Reads, runInputVerb)
+	}
 }
 
 // ADR 0593 §7 (C9): a compose ask naming the node-engine's repository builds its composer command in the Go module at the
@@ -168,7 +202,7 @@ func TestAComposeAskBuildsTheNodeEnginesComposerAtItsRoot(t *testing.T) {
 		t.Fatal(err)
 	}
 	ans := out.(delivery.ComposeAnswer)
-	key := delivery.ComposerKey("novox/mesh-host", composeCommit, delivery.RootPath, nodeEngineComposer, delivery.ToolchainUsed{Version: "go1.26.0", Recipe: m.Recipe.Version()})
+	key := delivery.ComposerKey("novox/mesh-host", composeCommit, delivery.RootPath, nodeEngineComposer, delivery.ToolchainUsed{Version: "go1.26.0", Recipe: m.Recipe.Version()}, nil)
 	var v composer.Verdict
 	if err := json.Unmarshal(ans.Verdict, &v); err != nil {
 		t.Fatal(err)

modules/mesh-build-go/cmd/mesh-build-go/fetch.go

@@ -19,6 +19,7 @@ import (
 
 	"git.novox.be/novox/mesh-catalog/modules/mesh-build-go/buildstep"
 	sdkstep "git.novox.be/novox/mesh-sdk/go/buildstep"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/forgekey"
 )
 
@@ -177,7 +178,9 @@ func (m *Module) fetchInto(ctx context.Context, req sdkstep.FetchRequest, id str
 			if taken[i], errs[i] = m.takeVersions(ctx, root, filepath.Join(tree, d), d, req.Packages, &pins); errs[i] != nil {
 				return
 			}
-			errs[i] = m.downloadModules(ctx, root, filepath.Join(tree, d), d, &pins)
+			var more []TakenVersion
+			more, errs[i] = m.downloadModules(ctx, root, repository, filepath.Join(tree, d), d, &pins, req.Packages)
+			taken[i] = append(taken[i], more...)
 		}()
 	}
 	wg.Wait()
@@ -194,21 +197,29 @@ func (m *Module) fetchInto(ctx context.Context, req sdkstep.FetchRequest, id str
 
 // downloadModules downloads and verifies the Go modules of the directory dir (d in the tree). A pin of a forge module
 // that Go cannot fetch is looked for among the forge's pull request heads and handed to Go by a modfile (pins.go); a
-// failure that names no such pin is the first failure.
-func (m *Module) downloadModules(ctx context.Context, root, dir, d string, pins *sync.Mutex) error {
+// failure that names no such pin is the first failure. A requirement at the zero version is taken from the asked
+// versions (pins.go takeZeroPins).
+func (m *Module) downloadModules(ctx context.Context, root, repository, dir, d string, pins *sync.Mutex, asked delivery.PackageVersions) ([]TakenVersion, error) {
+	var taken []TakenVersion
 	for {
 		failure := m.downloadAndVerify(ctx, dir, d)
 		if failure == nil {
-			return nil
+			return taken, nil
+		}
+		// A requirement at the zero version names no commit: it is taken from the asked versions or the trunk's latest.
+		took, err := m.takeZeroPins(ctx, root, repository, dir, d, failure.Error(), asked, pins)
+		taken = append(taken, took...)
+		if err != nil {
+			return taken, err
 		}
 		pins.Lock()
 		progress, err := m.resolvePins(ctx, root, dir, failure.Error())
 		pins.Unlock()
 		if err != nil {
-			return err
+			return taken, err
 		}
-		if !progress {
-			return failure
+		if !progress && len(took) == 0 {
+			return taken, failure
 		}
 	}
 }
@@ -337,6 +348,7 @@ func (m *Module) goEnvFor(dir string) []string {
 // net for a caller that never released one (issue 1839, ADR 0509).
 func (m *Module) CleanWorkspaces(now time.Time) {
 	m.sweepSaid(m.spaces().Sweep(now, buildstep.UnheldBound))
+	m.SweepKept(now, KeptBound)
 }
 
 // clock is the time now: Now when a test set it, else the wall clock.
@@ -351,15 +363,33 @@ func (m *Module) now() time.Time { return m.clock() }
 // causeLine is the first line of a go command's output that says something other than Go's own progress: `go:
 // downloading ...` comes first when Go fetches a module, and `# <package>` heads a compile error of go build or go vet
 // (issue 1703: the reason said only the package), and the cause of a failure on a later line.
+//
+// A cause Go writes over several lines keeps its indented continuation lines, joined by a space: a module graph error
+// is "X requires" with the module that fails, and why, on the next line (issue 1966: the composer's reason ended at
+// "requires" and hid "golang.org/x/tools@v0.42.0: module lookup disabled").
 func causeLine(s string) string {
-	for _, l := range strings.Split(s, "\n") {
+	lines := strings.Split(s, "\n")
+	for i, l := range lines {
 		if l = strings.TrimSpace(l); l != "" && !strings.HasPrefix(l, "go: downloading ") && !strings.HasPrefix(l, "# ") {
-			return l
+			return withContinuation(l, lines[i+1:])
 		}
 	}
 	return firstLine(s)
 }
 
+// withContinuation is first with each following line Go indented under it, trimmed and joined by a space.
+func withContinuation(first string, rest []string) string {
+	for _, l := range rest {
+		if !strings.HasPrefix(l, "\t") && !strings.HasPrefix(l, "    ") {
+			break
+		}
+		if l = strings.TrimSpace(l); l != "" {
+			first += " " + l
+		}
+	}
+	return first
+}
+
 func firstLine(s string) string {
 	for _, l := range strings.Split(s, "\n") {
 		if l = strings.TrimSpace(l); l != "" {

modules/mesh-build-go/cmd/mesh-build-go/fetch_test.go

@@ -309,9 +309,14 @@ func TestCauseLineSkipsProgressAndThePackageHeading(t *testing.T) {
 		"go: downloading x v1\n# git.example/m/cmd\n./main.go:3:2: undefined: y\n": "./main.go:3:2: undefined: y",
 		"\ngo: example.com/x@v1: reading: 404\n":                                   "go: example.com/x@v1: reading: 404",
 		"go: downloading x v1\n":                                                   "go: downloading x v1",
+		// issue 1966: a module graph error goes on, indented, on the next line; a later error is not taken in.
+		"a.go:3:8: x@v1 requires\n\ty@v2: module lookup disabled by GOPROXY=off\nb.go:1:1: other\n": "a.go:3:8: x@v1 requires y@v2: module lookup disabled by GOPROXY=off",
 	} {
 		if got := causeLine(in); got != want {
 			t.Errorf("causeLine(%q) = %q, want %q", in, got, want)
 		}
+		if got := compileError(in); got != want {
+			t.Errorf("compileError(%q) = %q, want %q", in, got, want)
+		}
 	}
 }

modules/mesh-build-go/cmd/mesh-build-go/kept.go

@@ -0,0 +1,130 @@
+package main
+
+// **Kept programs have tools and a sweep** (novox/hq issue 1921, the seams review's must 2): the programs this module builds
+// from a commit and keeps under its cache so each commit is built once on a node, the composers of compose asks and the
+// programs of run asks, are read by build_go_kept, removed one by one by build_go_kept_drop, and swept when unused for
+// KeptBound. A use touches the program's file, so its modification time is its last use.
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"sync"
+	"time"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+// The tools of the kept programs.
+const (
+	KeptTool     = "build_go_kept"
+	KeptDropTool = "build_go_kept_drop"
+)
+
+// KeptBound is how long a kept program that no ask used is kept: a month, longer than any group lives, so only the build
+// of a commit nobody asks about any more goes.
+const KeptBound = 30 * 24 * time.Hour
+
+// keptKinds are the cache directories of kept programs and the name of the program in each key's directory.
+var keptKinds = map[string]string{"composers": "mesh-compose", "programs": "program"}
+
+// KeptProgram is one kept program: its kind (the cache directory), its key, its size and when an ask last used it.
+type KeptProgram struct {
+	Kind     string    `json:"kind"`
+	Key      string    `json:"key"`
+	Bytes    int64     `json:"bytes"`
+	LastUsed time.Time `json:"last-used"`
+}
+
+// programPath is where the program of kind and key is kept.
+func (m *Module) programPath(kind, key string) string {
+	return filepath.Join(m.Cache, kind, key, keptKinds[kind])
+}
+
+// lockOf is the mutex that guards the program at path against a build or a use while it is dropped.
+func lockOf(path string) *sync.Mutex {
+	l, _ := composerLocks.LoadOrStore(path, &sync.Mutex{})
+	return l.(*sync.Mutex)
+}
+
+// touch records a use of the kept program at path.
+func touch(path string, at time.Time) { _ = os.Chtimes(path, at, at) }
+
+// Kept lists the kept programs, composers then programs, each kind by key.
+func (m *Module) Kept() []KeptProgram {
+	out := []KeptProgram{}
+	for _, kind := range []string{"composers", "programs"} {
+		entries, _ := os.ReadDir(filepath.Join(m.Cache, kind))
+		for _, e := range entries {
+			if !e.IsDir() {
+				continue
+			}
+			st, err := os.Stat(m.programPath(kind, e.Name()))
+			if err != nil || !st.Mode().IsRegular() {
+				continue
+			}
+			out = append(out, KeptProgram{Kind: kind, Key: e.Name(), Bytes: st.Size(), LastUsed: st.ModTime().UTC()})
+		}
+	}
+	return out
+}
+
+// DropKept removes the kept program of kind and key; one already gone is no error.
+func (m *Module) DropKept(kind, key string) error {
+	if _, ok := keptKinds[kind]; !ok {
+		return fmt.Errorf("a kept program is of kind composers or programs, not %q", kind)
+	}
+	if key == "" || key != filepath.Base(key) || key == "." || key == ".." {
+		return fmt.Errorf("%q is no kept program's key", key)
+	}
+	exe := m.programPath(kind, key)
+	l := lockOf(exe)
+	l.Lock()
+	defer l.Unlock()
+	return os.RemoveAll(filepath.Dir(exe))
+}
+
+// SweepKept removes the kept programs no ask used within bound before now, and answers what it removed.
+func (m *Module) SweepKept(now time.Time, bound time.Duration) []KeptProgram {
+	var gone []KeptProgram
+	for _, k := range m.Kept() {
+		if now.Sub(k.LastUsed) <= bound {
+			continue
+		}
+		if m.DropKept(k.Kind, k.Key) == nil {
+			gone = append(gone, k)
+		}
+	}
+	sort.Slice(gone, func(i, j int) bool { return gone[i].Key < gone[j].Key })
+	if len(gone) > 0 && m.Say != nil {
+		m.Say("removed %d kept programs no ask used within %s", len(gone), bound)
+	}
+	return gone
+}
+
+// keptTools are the tools that read and drop the kept programs: no guard and no floor, since they only free room.
+func (m *Module) keptTools() []stdio.Tool {
+	return []stdio.Tool{
+		{Name: KeptTool,
+			Description: "The programs this node keeps, built from a commit so each commit is built once: the composers of compose asks and " +
+				"the checking programs of run asks, each with its kind, key, size in bytes and when an ask last used it. One no ask used " +
+				"for 30 days is removed. Read-only.",
+			Run: func(map[string]any) (any, error) { return map[string]any{"kept": m.Kept()}, nil }},
+		{Name: KeptDropTool,
+			Description: "Remove one kept program by its kind (composers or programs) and key, as build_go_kept names them: the next ask " +
+				"for that commit builds it again. One already gone is no error.",
+			Input: map[string]any{"type": "object", "properties": map[string]any{
+				"kind": map[string]any{"type": "string", "enum": []string{"composers", "programs"}},
+				"key":  map[string]any{"type": "string", "description": "the key build_go_kept names"},
+			}, "required": []string{"kind", "key"}},
+			Run: func(args map[string]any) (any, error) {
+				kind, _ := args["kind"].(string)
+				key, _ := args["key"].(string)
+				if err := m.DropKept(kind, key); err != nil {
+					return nil, err
+				}
+				return map[string]any{"dropped": key, "kind": kind}, nil
+			}},
+	}
+}

modules/mesh-build-go/cmd/mesh-build-go/kept_test.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func keepProgram(t *testing.T, m *Module, kind, key string, size int, used time.Time) {
+	t.Helper()
+	exe := m.programPath(kind, key)
+	if err := os.MkdirAll(filepath.Dir(exe), 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(exe, make([]byte, size), 0o700); err != nil {
+		t.Fatal(err)
+	}
+	touch(exe, used)
+}
+
+func toolOf(t *testing.T, m *Module, name string) func(map[string]any) (any, error) {
+	t.Helper()
+	for _, tool := range m.Tools(m.StepTools()) {
+		if tool.Name == name {
+			return tool.Run
+		}
+	}
+	t.Fatalf("no tool %s", name)
+	return nil
+}
+
+// Seams review must 2 (issue 1921): the kept composers and programs are listed with their size and last use, dropped one
+// by one, and swept with the workspaces when unused past KeptBound; a use keeps a program.
+func TestKeptProgramsAreListedDroppedAndSwept(t *testing.T) {
+	m, _ := fetchModule(t, &fakeStep{})
+	now := time.Now().UTC().Truncate(time.Second)
+	keepProgram(t, m, "composers", "old", 10, now.Add(-KeptBound-time.Hour))
+	keepProgram(t, m, "programs", "recent", 20, now.Add(-time.Hour))
+	keepProgram(t, m, "programs", "gone", 30, now)
+
+	out, err := toolOf(t, m, KeptTool)(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	list := out.(map[string]any)["kept"].([]KeptProgram)
+	if len(list) != 3 || list[0].Kind != "composers" || list[0].Key != "old" || list[0].Bytes != 10 || !list[0].LastUsed.Equal(now.Add(-KeptBound-time.Hour)) {
+		t.Fatalf("the kept programs = %+v", list)
+	}
+
+	for _, bad := range []map[string]any{{"kind": "nope", "key": "gone"}, {"kind": "programs", "key": "../composers"}, {"kind": "programs", "key": ""}} {
+		if _, err := toolOf(t, m, KeptDropTool)(bad); err == nil {
+			t.Errorf("dropped with %v", bad)
+		}
+	}
+	for i := 0; i < 2; i++ { // a second drop is no error
+		if _, err := toolOf(t, m, KeptDropTool)(map[string]any{"kind": "programs", "key": "gone"}); err != nil {
+			t.Fatalf("drop %d: %v", i, err)
+		}
+	}
+	if _, err := os.Stat(m.programPath("programs", "gone")); !os.IsNotExist(err) {
+		t.Error("the dropped program is still kept")
+	}
+
+	// The sweep runs with the workspaces' (CleanWorkspaces, on its timer).
+	m.CleanWorkspaces(now)
+	if got := m.Kept(); len(got) != 1 || got[0].Key != "recent" {
+		t.Fatalf("kept after the sweep = %+v", got)
+	}
+}

modules/mesh-build-go/cmd/mesh-build-go/main.go

@@ -58,6 +58,7 @@ func main() {
 	m.Settings = m.Home + "/settings.json"
 	m.ReadKept = readOf(stdio.State(KeptState)).Get
 	m.ReadManifest = readOf(stdio.State(ManifestsState)).Get
+	m.AskInput = stdio.Ask
 	m.Probe = ProbeGo(m.Home, m.Cache)
 	m.Bubblewrap = ProbeBubblewrap
 	// Outside a launch by the runtime — a build, a check — there is no node and no state to write.

modules/mesh-build-go/cmd/mesh-build-go/module.go

@@ -93,7 +93,12 @@ type Module struct {
 	// ReadManifest reads a key of the delivery indexer's manifests state (ManifestsState), which a compose ask's request
 	// names its manifests by (compose.go); GoModCache, when set, is the Go module cache in place of Cache's (a test).
 	ReadManifest func(key string) (json.RawMessage, error)
-	GoModCache   string
+	// AskInput asks a seat verb the module invokes (module.json) as the runtime calls it (stdio.Ask): the verb a run ask's
+	// input names, answering the input by its digest (delivery.RunInput.Read).
+	AskInput func(key string, body any) (json.RawMessage, error)
+	// PlaceHead, when set, lays a run's head at a directory instead of fetching it (a test).
+	PlaceHead  func(ctx context.Context, h delivery.RunHead, dir string) error
+	GoModCache string
 
 	spacesOnce sync.Once
 	workspaces *buildstep.Workspaces

modules/mesh-build-go/cmd/mesh-build-go/module_test.go

@@ -115,7 +115,7 @@ func TestAGoThatCannotBeRunRefusesEveryStepAndHealthIsUnhealthy(t *testing.T) {
 		{Name: "short_probe", Run: run},
 	}, m.StepTools()...)
 	for _, tool := range m.Tools(steps) {
-		if tool.Name == StatusTool || tool.Name == HealthTool || tool.Name == StepReadTool || tool.Name == StepsReadTool || tool.Name == ToolchainsReadTool || tool.Name == ReleaseTool || tool.Name == StepEndTool {
+		if tool.Name == StatusTool || tool.Name == HealthTool || tool.Name == StepReadTool || tool.Name == StepsReadTool || tool.Name == ToolchainsReadTool || tool.Name == ReleaseTool || tool.Name == KeptTool || tool.Name == KeptDropTool || tool.Name == StepEndTool {
 			continue
 		}
 		var reason string

modules/mesh-build-go/cmd/mesh-build-go/pins.go

@@ -12,16 +12,24 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io/fs"
+	"maps"
 	"os"
 	"path/filepath"
 	"regexp"
+	"slices"
 	"strings"
+	"sync"
 
+	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/forgekey"
 )
 
 const forgePrefix = "git.novox.be/novox/"
 
+// zeroShort is the 12 digits a requirement at the zero version v0.0.0-00010101000000-000000000000 ends in: no commit.
+const zeroShort = "000000000000"
+
 var pseudoVersion = regexp.MustCompile(`[-.][0-9]{14}-([0-9a-f]{12})$`)
 
 // pin is a requirement of a go.mod on a commit of a repository of the forge, by a pseudo-version.
@@ -107,6 +115,9 @@ func (m *Module) resolvePins(ctx context.Context, root, dir, failure string) (bo
 	}
 	progress := false
 	for _, p := range forgePins(string(raw)) {
+		if p.short == zeroShort {
+			continue // takeZeroPins': a requirement at the zero version names no commit to look for
+		}
 		if !strings.Contains(failure, p.short) || strings.Contains(done, "replace "+p.module+" =>") {
 			continue
 		}
@@ -241,3 +252,141 @@ func absoluteReplaces(body []byte, dir string) []byte {
 	}
 	return []byte(strings.Join(lines, "\n"))
 }
+
+// takeZeroPins takes, for each requirement of dir's go.mod at the zero version that a go failure names, the version it is
+// built against (ADR 0573 §2, §4: whatever go.mod names): the commit the ask names for the package; else the head of
+// the package's repository among the asked versions (the check's or try's members: another package of the same
+// repository names it); else the latest published version, the trunk's head. It never looks for the commit
+// 000000000000 among the pull request heads. It answers what it took; none when no zero requirement is named.
+func (m *Module) takeZeroPins(ctx context.Context, root, repository, dir, d, failure string, asked delivery.PackageVersions, pins *sync.Mutex) ([]TakenVersion, error) {
+	raw, err := os.ReadFile(filepath.Join(dir, "go.mod"))
+	if err != nil || !strings.Contains(failure, zeroShort) {
+		return nil, nil
+	}
+	resolved := map[string]string{}
+	if modfile, ok := m.pinModfile(dir); ok {
+		if b, err := os.ReadFile(modfile); err == nil {
+			resolved, _ = goModRequirements(string(b))
+			for module := range resolved {
+				if strings.Contains(string(b), "replace "+module+" =>") {
+					resolved[module] = "replaced"
+				}
+			}
+		}
+	}
+	var taken []TakenVersion
+	for _, p := range forgePins(string(raw)) {
+		if p.short != zeroShort {
+			continue
+		}
+		if v := resolved[p.module]; v != "" && !strings.HasSuffix(v, zeroShort) {
+			continue // taken before
+		}
+		named := "v0.0.0-00010101000000-" + zeroShort
+		if "novox/"+p.repo == repository {
+			// A module of the checked repository itself: it is in the fetched tree and nowhere else, since nothing of the
+			// repository is published before its merge. Every module of the tree goes in, as one may require another.
+			own, err := m.useOwnModules(dir, root, p.repo)
+			if err != nil {
+				return taken, fmt.Errorf("the requirement of %s at the zero version: %w", p.module, err)
+			}
+			if !slices.Contains(own, p.module) {
+				return taken, fmt.Errorf("the requirement of %s at the zero version: no module of that path is in the fetched tree of %s, and nothing of a repository is published before its merge", p.module, repository)
+			}
+			tv := TakenVersion{Dir: d, Package: p.module, Named: named, Built: "the fetched tree", Said: "a module of the checked repository: built from its tree"}
+			if m.Say != nil {
+				m.Say("%s: %s names no commit; built from the fetched tree of %s", d, p.module, repository)
+			}
+			taken = append(taken, tv)
+			continue
+		}
+		tv := TakenVersion{Dir: d, Package: p.module, Asked: askedFor(asked, p), Named: named}
+		why := "the ask names it"
+		if tv.Asked == "" {
+			tv.Asked, why = "latest", "the ask names no commit of its repository, so its latest published version"
+		} else if _, ok := asked[p.module]; !ok {
+			why = "the head of its repository among the asked versions"
+		}
+		if err := m.takeVersion(ctx, root, dir, &tv, pins); err != nil {
+			return taken, fmt.Errorf("the requirement of %s at the zero version: %w", p.module, err)
+		}
+		tv.Said = strings.TrimPrefix(tv.Said+"; "+why, "; ")
+		if m.Say != nil {
+			m.Say("%s: %s names no commit; built at %s (%s)", d, p.module, tv.Built, why)
+		}
+		taken = append(taken, tv)
+	}
+	return taken, nil
+}
+
+// askedFor is the commit the ask names for the package p: its own, else that of the first package of the same repository
+// in order (the members' heads are by repository), else none.
+func askedFor(asked delivery.PackageVersions, p pin) string {
+	if c := asked[p.module]; c != "" {
+		return c
+	}
+	for _, pkg := range slices.Sorted(maps.Keys(asked)) {
+		if pkg == forgePrefix+p.repo || strings.HasPrefix(pkg, forgePrefix+p.repo+"/") {
+			return asked[pkg]
+		}
+	}
+	return ""
+}
+
+// useOwnModules replaces, in dir's temporary modfile, every module of the fetched tree whose path lies in the repository
+// repo by its directory in the tree (once), and answers the paths of those modules. A replace of a module dir does not
+// require is harmless to Go; one module of a repository requires another of it at the zero version.
+func (m *Module) useOwnModules(dir, root, repo string) ([]string, error) {
+	tree := filepath.Join(root, "tree")
+	prefix := forgePrefix + repo
+	type found struct{ module, where string }
+	var mods []found
+	err := filepath.WalkDir(tree, func(path string, e fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if e.IsDir() {
+			if n := e.Name(); n == ".git" || n == "vendor" || n == "node_modules" {
+				return filepath.SkipDir
+			}
+			return nil
+		}
+		if e.Name() != "go.mod" {
+			return nil
+		}
+		raw, err := os.ReadFile(path)
+		if err != nil {
+			return err
+		}
+		for _, line := range strings.Split(string(raw), "\n") {
+			if f := strings.Fields(line); len(f) == 2 && f[0] == "module" {
+				if mod := strings.Trim(f[1], `"`); (mod == prefix || strings.HasPrefix(mod, prefix+"/")) && filepath.Dir(path) != dir {
+					mods = append(mods, found{mod, filepath.Dir(path)})
+				}
+				break
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	modfile, _ := m.pinModfile(dir)
+	done := ""
+	if modfile != "" {
+		if b, err := os.ReadFile(modfile); err == nil {
+			done = string(b)
+		}
+	}
+	var paths []string
+	for _, f := range mods {
+		paths = append(paths, f.module)
+		if strings.Contains(done, "replace "+f.module+" =>") {
+			continue
+		}
+		if err := m.replaceInModfile(dir, f.module, f.where); err != nil {
+			return nil, err
+		}
+	}
+	return paths, nil
+}

modules/mesh-build-go/cmd/mesh-build-go/pins_test.go

@@ -290,3 +290,112 @@ func TestARelativeReplaceStillResolvesInTheTemporaryModfile(t *testing.T) {
 		t.Fatalf("go mod verify in the pins directory: %v\n%s", err, out)
 	}
 }
+
+// A go.mod requirement at the zero version v0.0.0-00010101000000-000000000000 names no commit (ADR 0573 §2, §4: whatever
+// go.mod names): it is taken from the commit the ask names for the package, else from the head of its repository among
+// the asked versions, else from the trunk's latest published version, and never looked for as the commit 000000000000
+// among the pull request heads.
+func TestARequirementAtTheZeroVersionIsTakenFromTheAskOrTheTrunk(t *testing.T) {
+	const sdk = "git.novox.be/novox/mesh-sdk/go"
+	zeroMod := "module fixture/member\n\ngo 1.26\n\nrequire (\n\t" + sdk + " v0.0.0-00010101000000-" + zeroShort + "\n)\n"
+	trunk := strings.Repeat("a", 40)
+	for _, c := range []struct {
+		name     string
+		packages map[string]any
+		download string // what go mod download -json answers
+		want     string // the version asked of go
+		head     bool   // the asked commit is on no trunk: only a pull request head carries it
+	}{
+		{name: "the ask names the package", packages: map[string]any{sdk: trunk}, want: sdk + "@" + trunk,
+			download: `{"Version":"v0.1.15-0.20261101000000-aaaaaaaaaaaa","Sum":"h1:zip="}`},
+		{name: "the ask names another package of its repository", packages: map[string]any{"git.novox.be/novox/mesh-sdk/other": trunk}, want: sdk + "@" + trunk,
+			download: `{"Version":"v0.1.15-0.20261101000000-aaaaaaaaaaaa","Sum":"h1:zip="}`},
+		{name: "the ask names the root of its repository, which no package of is published", packages: map[string]any{"git.novox.be/novox/mesh-sdk": trunk}, want: sdk + "@" + trunk,
+			download: `{"Version":"v0.1.15-0.20261101000000-aaaaaaaaaaaa","Sum":"h1:zip="}`},
+		{name: "the ask names the head of a pull request", packages: map[string]any{sdk: commitSHA}, want: sdk + "@" + commitSHA, head: true},
+		{name: "the ask names nothing of its repository", packages: map[string]any{"git.novox.be/novox/mesh-tools/go": trunk}, want: sdk + "@latest",
+			download: `{"Version":"v0.1.20-0.20261104000000-bbbbbbbbbbbb","Sum":"h1:zip="}`},
+		{name: "no ask", want: sdk + "@latest", download: `{"Version":"v0.1.20-0.20261104000000-bbbbbbbbbbbb","Sum":"h1:zip="}`},
+	} {
+		t.Run(c.name, func(t *testing.T) {
+			h, states := newPinHarness(t, zeroMod, false, pullList)
+			base := h.m.Run
+			h.m.Run = func(ctx context.Context, env []string, name string, args ...string) forgekey.Ran {
+				line := name + " " + strings.Join(args, " ")
+				switch {
+				case name == "go" && strings.Contains(line, " mod download -json "):
+					h.mu.Lock()
+					h.cmds = append(h.cmds, cmdRecord{env: env, line: line})
+					h.mu.Unlock()
+					if c.head {
+						return forgekey.Ran{Status: 1, Stdout: `{"Error":"invalid version: unknown revision ` + commitSHA[:12] + `"}`}
+					}
+					return forgekey.Ran{Stdout: c.download}
+				case name == "go" && strings.Contains(line, " mod download") && !strings.Contains(strings.Join(env, " "), "-modfile="):
+					return forgekey.Ran{Status: 1, Stderr: "go: " + sdk + "@v0.0.0-00010101000000-" + zeroShort + ": invalid version: unknown revision " + zeroShort + "\n"}
+				}
+				return base(ctx, env, name, args...)
+			}
+			args := map[string]any{"repository": "novox/mesh-delivery", "commit": commitSHA}
+			if c.packages != nil {
+				args["packages"] = c.packages
+			}
+			if _, err := fetchTool(t, h.m)(args); err != nil {
+				t.Fatal(err)
+			}
+			st := states.waitEnd(t)
+			if st.State != delivery.StepPassed {
+				t.Fatalf("the step ended %s: %s", st.State, st.Reason)
+			}
+			if !h.ran(" mod download -json " + c.want) {
+				t.Errorf("go was not asked for %s:\n%s", c.want, strings.Join(h.f.lines(), "\n"))
+			}
+			// The pull request heads are listed only to place an asked head, never to look for the commit of zeros.
+			if listed := h.ran("ls-remote"); listed != c.head {
+				t.Errorf("the pull request heads were listed: %v, want %v", listed, c.head)
+			}
+			if h.ran("pinned/mesh-sdk@" + zeroShort) {
+				t.Error("a repository was placed at the commit of zeros")
+			}
+		})
+	}
+}
+
+// A requirement at the zero version of a module of the checked repository itself (a nested module not yet published, which
+// another module of the repository requires) is built from the fetched tree, and never asked of Go or the forge (issue 1921).
+func TestARequirementAtTheZeroVersionOfTheCheckedRepositorysOwnModuleIsTakenFromItsTree(t *testing.T) {
+	const own = "git.novox.be/novox/mesh-delivery/nested/go"
+	zeroMod := "module fixture/member\n\ngo 1.26\n\nrequire (\n\t" + own + " v0.0.0-00010101000000-" + zeroShort + "\n)\n"
+	h, states := newPinHarness(t, zeroMod, false, pullList)
+	base := h.m.Run
+	h.m.Run = func(ctx context.Context, env []string, name string, args ...string) forgekey.Ran {
+		line := name + " " + strings.Join(args, " ")
+		if name == "go" && strings.Contains(line, " mod download") && !strings.Contains(strings.Join(env, " "), "-modfile=") {
+			trees, _ := filepath.Glob(filepath.Join(h.m.Work, "*", "tree"))
+			for _, tree := range trees {
+				os.MkdirAll(filepath.Join(tree, "nested", "go"), 0o755)
+				os.WriteFile(filepath.Join(tree, "nested", "go", "go.mod"), []byte("module "+own+"\n\ngo 1.26\n"), 0o644)
+			}
+			return forgekey.Ran{Status: 1, Stderr: "go: " + own + "@v0.0.0-00010101000000-" + zeroShort + ": invalid version: unknown revision " + zeroShort + "\n"}
+		}
+		return base(ctx, env, name, args...)
+	}
+	if _, err := fetchTool(t, h.m)(map[string]any{"repository": "novox/mesh-delivery", "commit": commitSHA}); err != nil {
+		t.Fatal(err)
+	}
+	st := states.waitEnd(t)
+	if st.State != delivery.StepPassed {
+		t.Fatalf("the step ended %s: %s", st.State, st.Reason)
+	}
+	modfiles, _ := filepath.Glob(filepath.Join(h.m.Work, "*", "pins", "*", "go.mod"))
+	if len(modfiles) != 1 {
+		t.Fatalf("modfiles = %v", modfiles)
+	}
+	body, _ := os.ReadFile(modfiles[0])
+	if !strings.Contains(string(body), "replace "+own+" => "+filepath.Join(filepath.Dir(filepath.Dir(filepath.Dir(modfiles[0]))), "tree", "nested", "go")) {
+		t.Errorf("the module of the tree was not replaced into the modfile:\n%s", body)
+	}
+	if h.ran(" mod download -json ") || h.ran("ls-remote") {
+		t.Error("a module of the checked repository was asked of Go or looked for among the pull request heads")
+	}
+}

modules/mesh-build-go/cmd/mesh-build-go/run.go

@@ -0,0 +1,132 @@
+package main
+
+// **A run ask runs a program built from a change, over heads it reads** (novox/hq ADR 0644, ADR 0656; issue 1921): the
+// checking program of a group's check. The module builds the program at the commit the ask names, once per
+// delivery.RunKey, as a compose ask builds a composer (programOf); fetches every head the ask names and lays each read-only
+// under the directory MESH_RUN_HEADS names, at `<owner>/<name>`; asks the seat verb the ask's input names for it by its
+// digest (as module.json invokes it; never a read of the asker's state, ADR 0596 §2) and writes it to the file
+// MESH_RUN_INPUT names; and runs the program shut off with the ask's
+// arguments: no network, none of the account. The answer is delivery.RunAnswer: the program's exit, the last line of its
+// standard output and the first line of its standard error. A program that fails is an answer, not a fault of the step.
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"git.novox.be/novox/mesh-catalog/modules/mesh-build-go/buildstep"
+	sdkstep "git.novox.be/novox/mesh-sdk/go/buildstep"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+)
+
+// run runs a run ask: the program of its commit, built once, over its heads and its input.
+func (m *Module) run(ctx context.Context, fetch buildstep.StepFunc, a delivery.StepAsk) (any, error) {
+	job := *a.Run
+	body, err := m.inputOf(job.Input)
+	if err != nil {
+		return nil, err
+	}
+	installed, err := m.Probe(ctx)
+	if err != nil {
+		return nil, err
+	}
+	key := delivery.RunKey(job.Program, delivery.ToolchainUsed{Version: installed, Recipe: m.Recipe.Version()}, a.Packages)
+	fetchArgs := sdkstep.FetchRequest{Repository: job.Program.Repository, Commit: job.Program.Commit, Packages: a.Packages}.Args()
+	exe, built, err := m.programOf(ctx, fetch, "programs", "checking program", key, fetchArgs, job.Program.Dir, job.Program.Package)
+	if err != nil {
+		return nil, err
+	}
+	ans, err := m.runProgram(ctx, exe, job, body)
+	if err != nil {
+		return nil, err
+	}
+	ans.Built, ans.Key = built, key
+	// The answer is written on the step key as one value: one over the bus's value limit (the input's bound) fails the
+	// step, naming its size, before it is written.
+	if raw, err := json.Marshal(ans); err != nil {
+		return nil, err
+	} else if len(raw) > delivery.RunInputBound {
+		return nil, fmt.Errorf("the checking program's answer is %d bytes, over the bound of %d bytes a step key holds", len(raw), delivery.RunInputBound)
+	}
+	return ans, nil
+}
+
+// inputOf is the input a run names, asked of the seat verb the ask names (module.json invokes it) and checked against
+// its digest and size: bytes that are not the input named refuse the ask.
+func (m *Module) inputOf(in delivery.RunInput) ([]byte, error) {
+	if m.AskInput == nil {
+		return nil, errors.New("this module asks no seat verb for a run's input")
+	}
+	raw, err := in.Read(m.AskInput)
+	if err != nil && raw != nil {
+		return nil, buildstep.Refuse("%v", err)
+	}
+	return raw, err
+}
+
+// placeHead lays one head's commit as a plain directory at dir, with no symlink in it; a test sets its own.
+func (m *Module) placeHead(ctx context.Context, h delivery.RunHead, dir string) error {
+	if m.PlaceHead != nil {
+		return m.PlaceHead(ctx, h, dir)
+	}
+	if err := os.MkdirAll(dir, 0o700); err != nil {
+		return err
+	}
+	if err := buildstep.FetchCommit(ctx, m.Run, dir, m.remote(h.Repository), h.Commit, "", m.fetchOptions(ctx, h.Repository, h.Commit, "")...); err != nil {
+		return err
+	}
+	if err := m.dissociate(ctx, dir); err != nil {
+		return err
+	}
+	if link := firstSymlink(dir); link != "" {
+		return fmt.Errorf("%s holds a symlink, %s", h.Repository, link)
+	}
+	return nil
+}
+
+// runProgram lays the heads and the input in a workspace of its own and runs exe shut off over them.
+func (m *Module) runProgram(ctx context.Context, exe string, job delivery.RunJob, input []byte) (delivery.RunAnswer, error) {
+	id := sdkstep.NewID()
+	done := m.spaces().Hold(id)
+	defer m.releaseSaid(id)
+	defer done()
+	ws := filepath.Join(m.Work, id)
+	heads := filepath.Join(ws, "heads")
+	for _, h := range job.Heads {
+		if err := m.placeHead(ctx, h, filepath.Join(heads, filepath.FromSlash(h.Repository))); err != nil {
+			return delivery.RunAnswer{}, fmt.Errorf("the head of %s at %s: %w", h.Repository, h.Commit, err)
+		}
+	}
+	if err := os.MkdirAll(heads, 0o700); err != nil {
+		return delivery.RunAnswer{}, err
+	}
+	file := filepath.Join(ws, "input")
+	if err := os.WriteFile(file, input, 0o600); err != nil {
+		return delivery.RunAnswer{}, err
+	}
+	run := m.Run
+	if !m.Inside {
+		iso := m.isolation(id, false)
+		iso.ReadOnly = append(iso.ReadOnly, exe)
+		iso.ReadOnlyInside = []string{heads} // bound after the workspace, so the program cannot change a head
+		run = buildstep.Isolated(m.Run, iso)
+	}
+	r := run(ctx, []string{delivery.RunHeadsEnv + "=" + heads, delivery.RunInputEnv + "=" + file}, exe, job.Args...)
+	if r.Err != "" && r.Status == 0 {
+		return delivery.RunAnswer{}, fmt.Errorf("the checking program could not run: %s", r.Err)
+	}
+	ans := delivery.RunAnswer{Exit: r.Status, Said: firstLine(r.Err + "\n" + r.Stderr)}
+	line := strings.TrimSpace(lastLine(r.Stdout))
+	switch {
+	case line == "":
+	case json.Valid([]byte(line)):
+		ans.Output = json.RawMessage(line)
+	default:
+		ans.Output, _ = json.Marshal(line)
+	}
+	return ans, nil
+}

modules/mesh-build-go/cmd/mesh-build-go/run_integration_test.go

@@ -0,0 +1,141 @@
+//go:build integration
+
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/nats-io/nats.go"
+	"github.com/nats-io/nats.go/jetstream"
+
+	"git.novox.be/novox/mesh-catalog/modules/mesh-build-go/buildstep"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/testbus"
+)
+
+// 1921/C3: a run ask put on the Go build seat's check stream is pulled by the module started whole on the real bus and
+// answered on its step key <node>.<ask id>: the program, run shut off over its heads and its input (asked by digest of the
+// seat verb the ask names, which a fake checker answers on the bus as the checker's verb input does), answers its last
+// line and exit; a program cannot write under its heads, and one
+// that dials the machine's network is shut off, and the answer says it failed.
+func TestARunAskIsAnsweredOnTheBusAndItsProgramIsShutOff(t *testing.T) {
+	needTools(t, "the shut-off run", "bash", "bwrap")
+	nc, err := nats.Connect(testbus.URL(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer nc.Close()
+	js, err := jetstream.New(nc)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ctx, stop := context.WithCancel(context.Background())
+	defer stop()
+	if err := buildstep.DeclareAskWorkers(ctx, js, delivery.AskGo, 2*time.Minute); err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { _ = js.DeleteStream(context.Background(), "SEAT_NODE_BUILD_GO") })
+	tcp, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tcp.Close()
+
+	states := newStates()
+	m := moduleWith(states, "go1.26.0")
+	m.Work, m.Cache, m.Home = t.TempDir(), t.TempDir(), t.TempDir()
+	m.Capacity = func() int { return 1 }
+	m.Run = StepRunner(m.Home)
+	for _, c := range m.caches() {
+		if err := os.MkdirAll(c, 0o700); err != nil {
+			t.Fatal(err)
+		}
+	}
+	m.PlaceHead = func(_ context.Context, h delivery.RunHead, dir string) error { return os.MkdirAll(dir, 0o700) }
+	body := `{"v":1}`
+	// The checker's verb input on the bus, and the module asking it as the runtime calls a seat verb it invokes.
+	asked := make(chan string, 4)
+	sub, err := nc.Subscribe("mesh.seat.mesh-delivery-checker.tool.input", func(msg *nats.Msg) {
+		var ask delivery.RunInputAsk
+		_ = json.Unmarshal(msg.Data, &ask)
+		asked <- ask.Digest
+		reply, _ := json.Marshal(map[string]any{"result": delivery.RunInputAnswer{Digest: ask.Digest, Input: []byte(body)}})
+		_ = msg.Respond(reply)
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer sub.Unsubscribe()
+	m.AskInput = func(key string, b any) (json.RawMessage, error) {
+		if key != runInputVerb {
+			return nil, errors.New("asked " + key)
+		}
+		data, _ := json.Marshal(b)
+		msg, err := nc.Request("mesh.seat.mesh-delivery-checker.tool.input", data, 5*time.Second)
+		if err != nil {
+			return nil, err
+		}
+		var r struct {
+			Result json.RawMessage `json:"result"`
+		}
+		return r.Result, json.Unmarshal(msg.Data, &r)
+	}
+
+	a := runAskOf(t, body)
+	key := delivery.RunKey(a.Run.Program, delivery.ToolchainUsed{Version: "go1.26.0", Recipe: m.Recipe.Version()}, nil)
+	exe := m.programPath("programs", key)
+	os.MkdirAll(filepath.Dir(exe), 0o700)
+	script := "#!/bin/bash\n" + `if touch "$MESH_RUN_HEADS/novox/mesh-sdk/x" 2>/dev/null; then echo '{"wrote":true}'; exit 9; fi; echo "start"; exec 3<>/dev/tcp/127.0.0.1/` + strings.Split(tcp.Addr().String(), ":")[1] + " || exit 7\n" + `echo '{"dialed":true}'` + "\n"
+	if err := os.WriteFile(exe, []byte(script), 0o700); err != nil {
+		t.Fatal(err)
+	}
+	p := m.Puller(fakeSteps(new([]string)), &buildstep.JetStreamAsks{JS: js, Language: delivery.AskGo})
+	p.PullWait = 200 * time.Millisecond
+	go p.Pull(ctx)
+
+	raw, err := delivery.EncodeStepAsk(a)
+	if err != nil {
+		t.Fatal(err)
+	}
+	subject, _ := delivery.AskSubject(delivery.AskGo, delivery.AskCheck)
+	if _, err := js.Publish(ctx, subject, raw); err != nil {
+		t.Fatal(err)
+	}
+	stepKey, _ := delivery.AskStepKey("ace", a.ID)
+	var step delivery.Step
+	for deadline := time.Now().Add(60 * time.Second); time.Now().Before(deadline); time.Sleep(50 * time.Millisecond) {
+		states.mu.Lock()
+		v := states.steps[stepKey]
+		states.mu.Unlock()
+		if len(v) > 0 && v[len(v)-1].State != delivery.StepRunning {
+			step = v[len(v)-1]
+			break
+		}
+	}
+	if step.State != delivery.StepPassed {
+		t.Fatalf("the run ask ended %q: %s", step.State, step.Reason)
+	}
+	var ans delivery.RunAnswer
+	if err := json.Unmarshal(step.Result, &ans); err != nil {
+		t.Fatal(err)
+	}
+	if ans.Key != key || ans.Exit != 7 || strings.Contains(string(ans.Output), "dialed") || string(ans.Output) != `"start"` {
+		t.Fatalf("the answer of a program that dials out = %+v output %s", ans, ans.Output)
+	}
+	select {
+	case d := <-asked:
+		if d != a.Run.Input.Digest {
+			t.Errorf("the verb input was asked %s, want %s", d, a.Run.Input.Digest)
+		}
+	default:
+		t.Error("the run's input was not asked of the checker's verb input")
+	}
+}

modules/mesh-build-go/cmd/mesh-build-go/run_test.go

@@ -0,0 +1,154 @@
+package main
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"git.novox.be/novox/mesh-catalog/modules/mesh-build-go/buildstep"
+	sdkstep "git.novox.be/novox/mesh-sdk/go/buildstep"
+	"git.novox.be/novox/mesh-sdk/go/composer"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/forgekey"
+)
+
+const runCommit = "5555555555555555555555555555555555555555"
+
+// runInputVerb is the seat verb a run ask's input is served on, as the checker names it in the ask.
+const runInputVerb = "seat:mesh-delivery-checker.input"
+
+// answersInput is a seat verb serving body by its digest, as the checker's verb input answers (delivery.RunInputAnswer).
+func answersInput(body string) func(key string, b any) (json.RawMessage, error) {
+	return func(key string, b any) (json.RawMessage, error) {
+		ask, _ := b.(delivery.RunInputAsk)
+		if sum := sha256.Sum256([]byte(body)); key != runInputVerb || ask.Digest != hex.EncodeToString(sum[:]) {
+			return nil, fmt.Errorf("the checker keeps no input %s", ask.Digest)
+		}
+		return json.Marshal(delivery.RunInputAnswer{Digest: ask.Digest, Input: []byte(body)})
+	}
+}
+
+func runAskOf(t *testing.T, body string) delivery.StepAsk {
+	t.Helper()
+	in, err := delivery.RunInputOf(runInputVerb, []byte(body))
+	if err != nil {
+		t.Fatal(err)
+	}
+	return delivery.StepAsk{ID: sdkstep.NewID(), Kind: delivery.AskCheck, Language: delivery.AskGo, Asker: "mesh-delivery-checker", At: time.Now(),
+		Run: &delivery.RunJob{Program: delivery.RunProgram{Repository: "novox/mesh-delivery", Commit: runCommit, Dir: ".", Package: "./cmd/prog"},
+			Heads: []delivery.RunHead{{Repository: "novox/mesh-sdk", Commit: runCommit}, {Repository: "novox/mesh-host", Commit: runCommit}},
+			Input: in, Args: []string{"-seats"}}}
+}
+
+// 1921/C1: a kept checking program is run over the input checked against its digest and the heads laid under
+// MESH_RUN_HEADS at <owner>/<name>, and the answer carries its exit and last line; nothing is fetched or built; a
+// program that fails, or says no JSON, is an answer; an input that is not the one named is refused; and the program was
+// kept under delivery.RunKey, so a second ask finds it.
+func TestAKeptProgramIsRunOverItsHeadsAndInput(t *testing.T) {
+	m := composeModule(t)
+	body := `{"v":1,"case":"x"}`
+	m.AskInput = answersInput(body)
+	m.PlaceHead = func(_ context.Context, h delivery.RunHead, dir string) error {
+		return os.MkdirAll(dir, 0o700)
+	}
+	a := runAskOf(t, body)
+	key := delivery.RunKey(a.Run.Program, delivery.ToolchainUsed{Version: "go1.26.0", Recipe: m.Recipe.Version()}, nil)
+	exe := m.programPath("programs", key)
+	os.MkdirAll(filepath.Dir(exe), 0o700)
+	script := "#!/bin/sh\n" +
+		`echo "noise"; echo "args $*" >&2; ` +
+		`printf '{"input":%s,"heads":"%s"}\n' "$(cat "$MESH_RUN_INPUT")" "$(cd "$MESH_RUN_HEADS" && ls -d */* | tr '\n' ' ')"; exit 3` + "\n"
+	if err := os.WriteFile(exe, []byte(script), 0o700); err != nil {
+		t.Fatal(err)
+	}
+	fetched := 0
+	fetch := func(context.Context, map[string]any) (any, error) { fetched++; return nil, nil }
+	out, err := m.run(context.Background(), fetch, a)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ans := out.(delivery.RunAnswer)
+	if ans.Built || ans.Key != key || fetched != 0 || ans.Exit != 3 || ans.Said != "args -seats" ||
+		string(ans.Output) != `{"input":{"v":1,"case":"x"},"heads":"novox/mesh-host novox/mesh-sdk "}` {
+		t.Fatalf("answer = %+v (fetched %d) output %s", ans, fetched, ans.Output)
+	}
+	if entries, _ := os.ReadDir(m.Work); len(entries) != 0 {
+		t.Errorf("the run's workspace was left: %v", entries)
+	}
+	// Shut off, the heads are bound read-only after the writable workspace, so a write under MESH_RUN_HEADS fails: a
+	// read-only bind before the workspace's is covered by it.
+	m.Inside = false
+	var argv []string
+	m.Run = func(_ context.Context, _ []string, _ string, args ...string) forgekey.Ran {
+		argv = args
+		return forgekey.Ran{Status: 0, Stdout: "{}"}
+	}
+	if _, err := m.run(context.Background(), fetch, a); err != nil {
+		t.Fatal(err)
+	}
+	line, ws, heads := " "+strings.Join(argv, " ")+" ", -1, -1
+	for i := 0; i+2 < len(argv); i++ {
+		switch {
+		case argv[i] == "--bind" && filepath.Dir(argv[i+1]) == m.Work:
+			ws = i
+		case argv[i] == "--ro-bind" && filepath.Base(argv[i+1]) == "heads" && argv[i+2] == argv[i+1]:
+			heads = i
+		}
+	}
+	if ws < 0 || heads < ws || !strings.Contains(line, " "+delivery.RunHeadsEnv+" "+argv[heads+1]+" ") {
+		t.Errorf("the heads are not bound read-only over the workspace: %s", line)
+	}
+	// An answer over the bus's value limit fails the step, naming its size.
+	m.Run = func(context.Context, []string, string, ...string) forgekey.Ran {
+		return forgekey.Ran{Status: 0, Stdout: `"` + strings.Repeat("x", delivery.RunInputBound) + `"`}
+	}
+	if _, err := m.run(context.Background(), fetch, a); err == nil || !strings.Contains(err.Error(), "over the bound") {
+		t.Errorf("an answer over the bound: %v", err)
+	}
+	m.Inside, m.Run = true, StepRunner(t.TempDir())
+	// An input other than the one named is refused, naming it; one the verb does not answer fails the step, saying why.
+	m.AskInput = func(_ string, b any) (json.RawMessage, error) {
+		return json.Marshal(delivery.RunInputAnswer{Digest: b.(delivery.RunInputAsk).Digest, Input: []byte(`{"other":1}`)})
+	}
+	if _, err := m.run(context.Background(), fetch, a); err == nil || !strings.Contains(err.Error(), "not the one the ask names") || !errors.As(err, new(*buildstep.Refusal)) {
+		t.Errorf("a wrong input: %v", err)
+	}
+	m.AskInput = answersInput(`{"v":2}`)
+	if _, err := m.run(context.Background(), fetch, a); err == nil || !strings.Contains(err.Error(), "keeps no input") {
+		t.Errorf("an input the verb does not answer: %v", err)
+	}
+}
+
+// 1921/C2 (F2): a compose ask's seats reach the composer: the module decodes and fills the request and writes it again,
+// and used to drop the seats.
+func TestAComposeAskKeepsItsSeats(t *testing.T) {
+	m := composeModule(t)
+	read, digests := indexerHolds(t, `{"module":"demo","version":"1"}`)
+	m.ReadManifest = read
+	a := composeAskOf(t, digests[0])
+	req := composer.Request{V: composer.Version, Seats: []json.RawMessage{json.RawMessage(`{"seat":"node-x"}`)},
+		Cases: []composer.Case{{Name: "change", Manifests: map[string]composer.Manifest{"demo": {Digest: digests[0]}}}}}
+	a.Compose.Request, _ = json.Marshal(req)
+	key := delivery.ComposerKey("novox/mesh-sdk", composeCommit, "go", composer.Package, delivery.ToolchainUsed{Version: "go1.26.0", Recipe: m.Recipe.Version()}, nil)
+	exe := m.composerPath(key)
+	os.MkdirAll(filepath.Dir(exe), 0o700)
+	script := "#!/bin/sh\n" + `if grep -q '"seats":\[{"seat":"node-x"}\]' "$2"; then S=true; else S=false; fi; ` +
+		`echo '{"v":1,"sdk":"stand-in","cases":[{"name":"change","manifests":{"demo":{"accepted":'$S'}}}]}'` + "\n"
+	os.WriteFile(exe, []byte(script), 0o700)
+	out, err := m.compose(context.Background(), nil, a)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var v composer.Verdict
+	if err := json.Unmarshal(out.(delivery.ComposeAnswer).Verdict, &v); err != nil || !v.Cases[0].Manifests["demo"].Accepted {
+		t.Fatalf("the composer did not receive the seats: %+v %v", v, err)
+	}
+}

modules/mesh-build-go/cmd/mesh-build-go/tools.go

@@ -45,6 +45,7 @@ func (m *Module) Tools(steps []StepTool) []stdio.Tool {
 	tools = append(tools, m.ReadTools()...)
 	tools = append(tools, buildstep.StepEndTool(StepEndTool, m.Node, m.stepScan(), m.Held))
 	tools = append(tools, m.releaseTool())
+	tools = append(tools, m.keptTools()...)
 	return append(tools,
 		stdio.Tool{Name: StatusTool,
 			Description: "What the Go build module is on this machine: the Go version its recipe builds with and the one installed, " +

modules/mesh-build-go/cmd/mesh-build-go/versions.go

@@ -105,6 +105,10 @@ func (m *Module) takeVersion(ctx context.Context, root, dir string, tv *TakenVer
 		// Not a commit Go can fetch: the head of a group's pull request (ADR 0573 §4), placed from the forge's heads.
 		// Whether it is one is the forge's fact (placePin), whatever go said.
 		failure := strings.TrimSpace(info.Error + "\n" + r.Err + "\n" + r.Stderr)
+		if !commitOK.MatchString(tv.Asked) {
+			// "latest" (the trunk's head) is no commit of a pull request: there is nothing to place.
+			return fmt.Errorf("go cannot fetch the latest version of %s, and the ask names no commit of its repository to build it at: either no version of it is published, or the forge did not answer: %s", tv.Package, causeLine(failure))
+		}
 		repo, sub, _ := strings.Cut(strings.TrimPrefix(tv.Package, forgePrefix), "/")
 		p := pin{module: tv.Package, repo: repo, sub: sub, short: tv.Asked[:12]}
 		pins.Lock()

modules/mesh-build-go/module.json

@@ -23,6 +23,9 @@
     "mesh-delivery-checker.kept",
     "mesh-delivery-indexer.manifests"
   ],
+  "invokes": [
+    "seat:mesh-delivery-checker.input"
+  ],
   "config": {
     "capacity": {
       "type": "number",
@@ -50,6 +53,8 @@
     "build_go_build",
     "build_go_imports",
     "build_go_release",
+    "build_go_kept",
+    "build_go_kept_drop",
     "build_go_step",
     "build_go_steps",
     "build_go_step_end",

modules/mesh-build-node/.gitignore

@@ -1 +1,3 @@
-mesh-build-node
+# the binary, built at the module or in its command directory; never the command directory itself
+/mesh-build-node
+/cmd/mesh-build-node/mesh-build-node

modules/mesh-build-node/cmd/mesh-build-node/build.go

@@ -13,6 +13,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"path"
 	"path/filepath"
 	"sort"
 	"strings"
@@ -37,6 +38,27 @@ type artifact struct {
 	Language    string   `json:"language"`
 	Entrypoints []string `json:"entrypoints"`
 	External    []string `json:"external"`
+	// Paths are the directories of a package artifact, relative to the module's: one, holding its package.json and
+	// its package-lock.json (as a Go package's, mesh-build-go gopackage.go); none means the module's directory.
+	Paths []string `json:"paths"`
+}
+
+// packageDir is the directory of a package artifact relative to its module's directory in dir: the one path it names
+// when that is a directory of the module holding a package.json (the contracts folders: ts/seats/<seat>/, each with its
+// own lock, ADR 0634 section 8), else the module's directory itself (a package that names no path, or source paths
+// beside the module's package.json: today's form).
+func (a artifact) packageDir(dir string) string {
+	if len(a.Paths) != 1 {
+		return "."
+	}
+	p := path.Clean(strings.TrimSuffix(a.Paths[0], "/"))
+	if p == "." || path.IsAbs(p) || p == ".." || strings.HasPrefix(p, "../") {
+		return "."
+	}
+	if _, err := os.Stat(filepath.Join(dir, filepath.FromSlash(p), "package.json")); err != nil {
+		return "."
+	}
+	return p
 }
 
 // BuildResult is what a passed build step says.
@@ -88,7 +110,8 @@ func (m *Module) build(ctx context.Context, args map[string]any) (any, error) {
 		return nil, err
 	}
 	if a.Kind == "package" {
-		return m.buildPackage(ctx, workspace, module, root, dir, a, publish)
+		at := a.packageDir(dir)
+		return m.buildPackage(ctx, workspace, module, root, filepath.Join(dir, filepath.FromSlash(at)), at, a, publish)
 	}
 	if why, err := lockProblem(dir, module); err != nil || why != "" {
 		if err == nil {

modules/mesh-build-node/cmd/mesh-build-node/check.go

@@ -16,6 +16,7 @@ import (
 	"fmt"
 	"io/fs"
 	"os"
+	"path"
 	"path/filepath"
 	"strings"
 	"time"
@@ -99,78 +100,89 @@ func (m *Module) test(ctx context.Context, args map[string]any) (any, error) {
 	if err != nil {
 		return nil, err
 	}
-	scripts, err := packageScripts(dir)
-	if err != nil {
-		return nil, err
-	}
-	sources, err := typeScriptFiles(dir)
-	if err != nil {
-		return nil, err
-	}
 	res := &TestResult{Workspace: workspace, Module: module, Level: level, By: sdkstep.By("mesh-build-node")}
 	script := "test"
 	if level == "integration" {
 		script = "test:integration"
 	}
-	hasScript := scripts[script] != ""
-	if level == "integration" && !hasScript {
-		res.Passed, res.NoTests, res.Why = true, true, "no tests: the package has no test:integration script"
-		return res, nil
-	}
-	if !hasScript && len(sources) == 0 {
-		res.Passed, res.NoTests, res.Why = true, true, "no tests: the package has no test script and no .ts files"
-		return res, nil
-	}
-	if err := m.provide(root); err != nil {
-		return nil, fmt.Errorf("providing the toolchain's packages to the workspace: %w", err)
-	}
 	where := module
 	if where == "" {
 		where = "."
 	}
+	targets, err := testTargets(dir, where)
+	if err != nil {
+		return nil, err
+	}
 	var check, run time.Duration
 	var failed []Failure
-	// a command that could not start is not a verdict: the step fails. One that ran and said no is.
-	ran := func(name string, r forgekey.Ran, report string) error {
-		if r.Err != "" {
-			return fmt.Errorf("%s could not be run: status %d %s: %s", name, r.Status, r.Err, firstLine(r.Stderr))
-		}
-		if r.Status != 0 {
-			failed = append(failed, testFailures(where, name, dir, r, report)...)
-		}
-		return nil
-	}
-	if len(sources) > 0 {
-		// A package that builds (a build or prepare script, which the fetch's --ignore-scripts never runs) is emitted
-		// by tsc into the workspace, shut off like every run step, so its tests find what they import of its own output
-		// (issue 1869: mesh-sdk's tests import ../dist); any other is type-checked without emitting.
-		name, line := "type-check", m.typeCheck(dir, sources)
-		if emit := m.emitBuild(dir, scripts); emit != nil {
-			name, line = "build", emit
-		}
-		start := m.now()
-		r := m.runIn(ctx, root, false, dir, nil, "node", line...)
-		check = m.now().Sub(start)
-		if err := ran(name, r, ""); err != nil {
+	tested := false
+	for _, tg := range targets {
+		scripts, err := packageScripts(tg.dir)
+		if err != nil {
 			return nil, err
 		}
-		res.Ran = append(res.Ran, name)
-	}
-	if hasScript && len(failed) == 0 {
-		start := m.now()
-		// node --test writes its TAP report to a file of the workspace (issue 1901), whatever the script prints itself
-		report := filepath.Join(root, ".mesh-node-test-"+level+".tap")
-		_ = os.Remove(report)
-		env := []string{"PATH=" + binDir(root) + ":" + pathOrDefault(), "npm_config_cache=" + filepath.Join(m.Toolchain.Paths.Cache, "npm"),
-			"NODE_OPTIONS=" + buildstep.NodeTestOptions(report)}
-		r := m.runIn(ctx, root, false, dir, env, "npm", scriptArgs(script)...)
-		run = m.now().Sub(start)
-		tap, _ := os.ReadFile(report)
-		_ = os.Remove(report)
-		if err := ran(script, r, string(tap)); err != nil {
+		sources, err := typeScriptFiles(tg.dir)
+		if err != nil {
 			return nil, err
 		}
-		res.Ran = append(res.Ran, script)
+		hasScript := scripts[script] != ""
+		if (level == "integration" && !hasScript) || (!hasScript && len(sources) == 0) {
+			continue
+		}
+		tested = true
+		if err := m.provide(root); err != nil {
+			return nil, fmt.Errorf("providing the toolchain's packages to the workspace: %w", err)
+		}
+		// a command that could not start is not a verdict: the step fails. One that ran and said no is.
+		ran := func(name string, r forgekey.Ran, report string) error {
+			if r.Err != "" {
+				return fmt.Errorf("%s could not be run: status %d %s: %s", name, r.Status, r.Err, firstLine(r.Stderr))
+			}
+			if r.Status != 0 {
+				failed = append(failed, testFailures(tg.where, name, tg.dir, r, report)...)
+			}
+			return nil
+		}
+		if len(sources) > 0 {
+			// A package that builds (a build or prepare script, which the fetch's --ignore-scripts never runs) is emitted
+			// by tsc into the workspace, shut off like every run step, so its tests find what they import of its own output
+			// (issue 1869: mesh-sdk's tests import ../dist); any other is type-checked without emitting.
+			name, line := "type-check", m.typeCheck(tg.dir, sources)
+			if emit := m.emitBuild(tg.dir, scripts); emit != nil {
+				name, line = "build", emit
+			}
+			start := m.now()
+			r := m.runIn(ctx, root, false, tg.dir, nil, "node", line...)
+			check += m.now().Sub(start)
+			if err := ran(name, r, ""); err != nil {
+				return nil, err
+			}
+			res.Ran = appendOnce(res.Ran, name)
+		}
+		if hasScript && len(failed) == 0 {
+			start := m.now()
+			// node --test writes its TAP report to a file of the workspace (issue 1901), whatever the script prints itself
+			report := filepath.Join(root, ".mesh-node-test-"+level+".tap")
+			_ = os.Remove(report)
+			env := []string{"PATH=" + binDir(root) + ":" + pathOrDefault(), "npm_config_cache=" + filepath.Join(m.Toolchain.Paths.Cache, "npm"),
+				"NODE_OPTIONS=" + buildstep.NodeTestOptions(report)}
+			r := m.runIn(ctx, root, false, tg.dir, env, "npm", scriptArgs(script)...)
+			run += m.now().Sub(start)
+			tap, _ := os.ReadFile(report)
+			_ = os.Remove(report)
+			if err := ran(script, r, string(tap)); err != nil {
+				return nil, err
+			}
+			res.Ran = appendOnce(res.Ran, script)
+		}
+	}
+	if !tested {
+		res.Passed, res.NoTests = true, true
+		res.Why = "no tests: the package has no test script and no .ts files"
+		if level == "integration" {
+			res.Why = "no tests: the package has no test:integration script"
+		}
+		return res, nil
 	}
 	res.Failed = failed
 	var why []string
@@ -294,3 +306,56 @@ func typeScriptFiles(dir string) ([]string, error) {
 	})
 	return out, err
 }
+
+// testTarget is a directory whose tests a level runs, and the name it is reported under.
+type testTarget struct{ dir, where string }
+
+// testTargets are the directories a module's tests run in: each TypeScript package artifact's own path when every
+// package the module declares names one (ADR 0634 §8: its package.json, its lock, its tests), else the module's
+// directory.
+func testTargets(dir, where string) ([]testTarget, error) {
+	whole := []testTarget{{dir, where}}
+	raw, err := os.ReadFile(filepath.Join(dir, "module.json"))
+	if err != nil {
+		return whole, nil
+	}
+	var mj struct {
+		Build struct {
+			Artifacts []artifact `json:"artifacts"`
+		} `json:"build"`
+	}
+	if json.Unmarshal(raw, &mj) != nil {
+		return whole, nil
+	}
+	var out []testTarget
+	seen := map[string]bool{}
+	for _, a := range mj.Build.Artifacts {
+		if a.Language != "typescript" {
+			continue
+		}
+		if a.Kind != "package" {
+			return whole, nil // a bundle is tested in its module's directory
+		}
+		at := a.packageDir(dir)
+		if at == "." {
+			return whole, nil
+		}
+		if !seen[at] {
+			seen[at] = true
+			out = append(out, testTarget{filepath.Join(dir, filepath.FromSlash(at)), path.Join(where, at)})
+		}
+	}
+	if len(out) == 0 {
+		return whole, nil
+	}
+	return out, nil
+}
+
+func appendOnce(list []string, s string) []string {
+	for _, x := range list {
+		if x == s {
+			return list
+		}
+	}
+	return append(list, s)
+}

modules/mesh-build-node/cmd/mesh-build-node/fetch.go

@@ -17,6 +17,7 @@ import (
 	"fmt"
 	"io/fs"
 	"os"
+	"path"
 	"path/filepath"
 	"regexp"
 	"sort"
@@ -210,8 +211,8 @@ func (m *Module) fetchInto(ctx context.Context, req sdkstep.FetchRequest, group
 	return res, nil
 }
 
-// typeScriptModules are the directories of the tree whose module.json declares a typescript artifact, relative to
-// it, in order.
+// typeScriptModules are the directories of the tree that a typescript artifact of a module.json is built in, relative to
+// it, in order: the module's directory for a bundle, the artifact's path for a package.
 func (m *Module) typeScriptModules(ctx context.Context, tree string) (dirs []string, packages map[string]bool, err error) {
 	r := m.Run(ctx, m.baseEnv(), "git", "-C", tree, "ls-files", "--", "module.json", "*/module.json")
 	if r.Status != 0 || r.Err != "" {
@@ -237,13 +238,21 @@ func (m *Module) typeScriptModules(ctx context.Context, tree string) (dirs []str
 		if json.Unmarshal(raw, &mj) != nil {
 			continue // a module.json the build step will refuse by name, not a fetch's business
 		}
+		// A bundle is built in its module's directory, a package in its own path (ADR 0634 §8: as at a repository's
+		// root, each package with its own lock); the first artifact to claim a directory decides it.
 		for _, a := range mj.Build.Artifacts {
-			if a.Language == "typescript" {
-				d := filepath.ToSlash(filepath.Dir(l))
-				dirs = append(dirs, d)
-				packages[d] = a.Kind == "package"
-				break
+			if a.Language != "typescript" {
+				continue
 			}
+			d := filepath.ToSlash(filepath.Dir(l))
+			if a.Kind == "package" {
+				d = path.Join(d, a.packageDir(filepath.Join(tree, filepath.FromSlash(d))))
+			}
+			if _, seen := packages[d]; seen {
+				continue
+			}
+			dirs = append(dirs, d)
+			packages[d] = a.Kind == "package"
 		}
 	}
 	sort.Strings(dirs)

modules/mesh-build-node/cmd/mesh-build-node/package.go

@@ -469,11 +469,13 @@ func fetchCommit(ctx context.Context, run forgekey.Runner, dir, remote, commit,
 // (publish) publishes it, from this module's own process with the registry's write credential, which no run step is
 // given: a version the registry lacks is published; the same packed file already there is done without a publish;
 // another packed file under that version fails `version taken:`. The reference is <name>@<version>, answered only when
-// the registry holds this build's file; a candidate answers its digest alone.
-func (m *Module) buildPackage(ctx context.Context, workspace, module, root, dir string, a artifact, publish bool) (any, error) {
-	rel := module
-	if rel == "" {
-		rel = "."
+// the registry holds this build's file; a candidate answers its digest alone. dir is the package's directory, at its
+// place in the module's.
+func (m *Module) buildPackage(ctx context.Context, workspace, module, root, dir, at string, a artifact, publish bool) (any, error) {
+	// rel is the package's directory in the workspace, as the fetch installed it (the shims lie under it).
+	rel := path.Join(module, at)
+	if module == "" {
+		rel = path.Join(".", at)
 	}
 	p, err := m.buildAndPack(ctx, root, dir, rel, publish)
 	if err != nil {

modules/mesh-build-node/cmd/mesh-build-node/package_paths_test.go

@@ -0,0 +1,93 @@
+package main
+
+import (
+	"context"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// A folder module (mesh-contracts' root, a domain folder) declares several package artifacts, each at its own path
+// with its own package.json and package-lock.json and none at the module's directory (ADR 0634 section 8).
+const folderManifest = `{"module":"c","build":{"artifacts":[` +
+	`{"name":"ts-a","kind":"package","language":"typescript","paths":["ts/seats/a"]},` +
+	`{"name":"ts-b","kind":"package","language":"typescript","paths":["ts/seats/b/"]}]}}`
+
+func folderFiles(prefix string) map[string]string {
+	files := map[string]string{prefix + "module.json": folderManifest}
+	for _, s := range []string{"a", "b"} {
+		files[prefix+"ts/seats/"+s+"/package.json"] = `{"name":"@x/` + s + `","version":"0.1.0","scripts":{"build":"tsc","test":"node --test"}}`
+		files[prefix+"ts/seats/"+s+"/package-lock.json"] = `{"lockfileVersion":3}`
+		files[prefix+"ts/seats/"+s+"/index.ts"] = "export const v = 1;\n"
+	}
+	return files
+}
+
+// The fetch installs each package artifact at its path from the lock there, and finds no lock missing at the module.
+func TestAFolderModulesPackagesAreInstalledEachAtItsPath(t *testing.T) {
+	m, f := fetchMachine(t, folderFiles("modules/c/"), nil)
+	out, err := m.fetch(context.Background(), fetchArgs)
+	if err != nil {
+		t.Fatal(err)
+	}
+	r := out.(FetchResult)
+	if len(r.Modules) != 2 || r.Modules[0] != "modules/c/ts/seats/a" || r.Modules[1] != "modules/c/ts/seats/b" || len(r.Installed) != 2 {
+		t.Errorf("result = %+v, want both package directories found and installed", r)
+	}
+	var prefixes []string
+	for _, c := range npmCalls(f) {
+		for i, a := range c.args {
+			if a == "--prefix" {
+				prefixes = append(prefixes, strings.TrimPrefix(c.args[i+1], filepath.Join(m.Work, r.Workspace, "tree")))
+			}
+		}
+	}
+	if len(prefixes) != 2 || prefixes[0] != "/modules/c/ts/seats/a" || prefixes[1] != "/modules/c/ts/seats/b" {
+		t.Errorf("npm ci ran with --prefix %v, want each package's own directory", prefixes)
+	}
+}
+
+// The build runs the package's script and pack in its own path, and the test level runs in each path.
+func TestAFolderModulesPackageIsBuiltAndTestedInItsPath(t *testing.T) {
+	m, f, work := newMachine(t)
+	workspaceWith(t, work, folderFiles(""))
+	f.effect = func(c call) {
+		if c.name == "npm" && len(c.args) > 0 && c.args[0] == "pack" {
+			for i, a := range c.args {
+				if a == "--pack-destination" {
+					write(t, filepath.Join(c.args[i+1], "x.tgz"), "packed", 0o644)
+				}
+			}
+		}
+	}
+	if _, err := m.build(context.Background(), map[string]any{"workspace": "w1", "module": ".", "artifact": "ts-b"}); err != nil {
+		t.Fatal(err)
+	}
+	want := filepath.Join(work, "w1", "tree", "ts", "seats", "b")
+	built := 0
+	for _, c := range f.calls {
+		if c.name == "npm" {
+			built++
+			if c.dir != want {
+				t.Errorf("%s ran in %s, want %s", joined(c), c.dir, want)
+			}
+		}
+	}
+	if built != 2 {
+		t.Errorf("%d npm commands, want the build and the pack", built)
+	}
+	f.calls = nil
+	res, err := m.test(context.Background(), testArgs("unit"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	tests := map[string]bool{}
+	for _, c := range f.calls {
+		if c.name == "npm" {
+			tests[c.dir] = true
+		}
+	}
+	if r := res.(*TestResult); !r.Passed || len(tests) != 2 || !tests[want] || !tests[filepath.Join(work, "w1", "tree", "ts", "seats", "a")] {
+		t.Errorf("unit level = %+v, ran tests in %v, want both package paths", r, tests)
+	}
+}

modules/mesh-delivery-gate/cmd/mesh-delivery-gate/bridge_test.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 	"sync"
 
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	sdk "git.novox.be/novox/mesh-sdk/go/delivery"
 )
 
@@ -24,7 +25,7 @@ type fakeMerges struct {
 	manual bool
 	failed error
 	// said are the messages the bridge wrote on FORGE, in order.
-	said []sdk.Forge
+	said []forgemsg.Forge
 }
 
 func newFakeMerges(f *fakeForge) *fakeMerges {
@@ -76,11 +77,11 @@ func (m *fakeMerges) Put(group string, v sdk.Merge) error {
 			err = f.refuse
 		}
 		f.mu.Unlock()
-		msg := sdk.Forge{Repository: p.Repository, Number: p.Number, Head: p.Head.Head}
+		msg := forgemsg.Forge{Repository: p.Repository, Number: p.Number, Head: p.Head.Head}
 		if err != nil {
-			msg.Kind, msg.Act, msg.Words = sdk.ForgeRefused, "merge", err.Error()
+			msg.Kind, msg.Act, msg.Words = forgemsg.ForgeRefused, "merge", err.Error()
 		} else {
-			msg.Kind, msg.Merge, msg.Root = sdk.ForgeMerged, strings.Repeat("c", 40), "root"
+			msg.Kind, msg.Merge, msg.Root = forgemsg.ForgeMerged, strings.Repeat("c", 40), "root"
 			msg.Trees = map[string]string{"app": "tree"}
 		}
 		m.say(msg)
@@ -89,12 +90,12 @@ func (m *fakeMerges) Put(group string, v sdk.Merge) error {
 }
 
 // say writes a message on FORGE and has the gate hear it, as the runtime does.
-func (m *fakeMerges) say(msg sdk.Forge) {
-	body, err := sdk.EncodeForge(msg)
+func (m *fakeMerges) say(msg forgemsg.Forge) {
+	body, err := forgemsg.EncodeForge(msg)
 	if err != nil {
 		panic(err)
 	}
-	event, err := sdk.ForgeEvent(msg.Repository, msg.Kind)
+	event, err := forgemsg.ForgeEvent(msg.Repository, msg.Kind)
 	if err != nil {
 		panic(err)
 	}

modules/mesh-delivery-gate/cmd/mesh-delivery-gate/bus_test.go

@@ -16,6 +16,7 @@ import (
 	"testing"
 	"time"
 
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	stdio "git.novox.be/novox/mesh-sdk/go"
 	"git.novox.be/novox/mesh-sdk/go/asks"
 	sdk "git.novox.be/novox/mesh-sdk/go/delivery"
@@ -582,7 +583,7 @@ func TestAPassingVerdictAsksTheApproveAndItsApproveMergesWithinSecondsOverARealB
 		t.Fatalf("the gate asked the forge to merge %d times: the bridge merges", n)
 	}
 	// The bridge says it merged; the mesh's source then holds the merge, in one write.
-	b.forgeSays(t, sdk.Forge{Kind: sdk.ForgeMerged, Repository: "novox/app", Number: 7, Head: head, Merge: strings.Repeat("b", 40),
+	b.forgeSays(t, forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/app", Number: 7, Head: head, Merge: strings.Repeat("b", 40),
 		Root: "r", Trees: map[string]string{"app": "t"}})
 	// The forge's own word that the pull request merged follows the bridge's (its webhook): the delivery ends merged.
 	b.publish(t, "mesh.mod.gitea.event.pull.merged", merged("novox/app", 7, head, strings.Repeat("b", 40)))
@@ -677,13 +678,13 @@ func (b *testBus) answer(t *testing.T, key, option string) time.Time {
 }
 
 // forgeSays is the forge bridge's message on FORGE, as its stream carries it.
-func (b *testBus) forgeSays(t *testing.T, f sdk.Forge) {
+func (b *testBus) forgeSays(t *testing.T, f forgemsg.Forge) {
 	t.Helper()
-	raw, err := sdk.EncodeForge(f)
+	raw, err := forgemsg.EncodeForge(f)
 	if err != nil {
 		t.Fatal(err)
 	}
-	event, err := sdk.ForgeEvent(f.Repository, f.Kind)
+	event, err := forgemsg.ForgeEvent(f.Repository, f.Kind)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -742,7 +743,7 @@ func TestAGroupOfTwoWithGreenChecksGetsOneAskAndOnItsApproveBothMergeOneAfterThe
 		t.Fatalf("the second member was handed before the first merged: %+v", again.Pulls)
 	}
 	one := first.Pulls[0]
-	b.forgeSays(t, sdk.Forge{Kind: sdk.ForgeMerged, Repository: one.Repository, Number: one.Number, Head: one.Head.Head,
+	b.forgeSays(t, forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: one.Repository, Number: one.Number, Head: one.Head.Head,
 		Merge: strings.Repeat("a", 40), Root: "r", Trees: map[string]string{"x": "t"}})
 	var both sdk.Merge
 	rt.until("the second member to be handed", eventWithin, func() bool { both = mergeAt(b, "feat/x"); return len(both.Pulls) == 2 })
@@ -750,7 +751,7 @@ func TestAGroupOfTwoWithGreenChecksGetsOneAskAndOnItsApproveBothMergeOneAfterThe
 		t.Fatalf("the second merge handed is %+v", both.Pulls)
 	}
 	two := both.Pulls[1]
-	b.forgeSays(t, sdk.Forge{Kind: sdk.ForgeMerged, Repository: two.Repository, Number: two.Number, Head: two.Head.Head,
+	b.forgeSays(t, forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: two.Repository, Number: two.Number, Head: two.Head.Head,
 		Merge: strings.Repeat("b", 40), Root: "r", Trees: map[string]string{"x": "t"}})
 	rt.until("source.main to hold both merges", eventWithin, func() bool {
 		e, err := b.kvs["source"].Get(ctx, sdk.SourceMainKey)

modules/mesh-delivery-gate/cmd/mesh-delivery-gate/holder_test.go

@@ -6,7 +6,7 @@ import (
 	"testing"
 	"time"
 
-	sdk "git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 )
 
 // The holder, end to end over fakes (novox/hq ADR 0239 *How it is checked*, cut by ADR 0539 §17): a pull request's head
@@ -241,9 +241,9 @@ func TestAMergedGroupEndsMergedWithSourceMainMoved(t *testing.T) {
 		t.Fatalf("source.main is %+v, wanted both merges", w.source.main)
 	}
 	// A merge that leaves no module.json carries no trees (issue 1367): the gate reads it, and refuses nothing.
-	msg := sdk.Forge{Kind: sdk.ForgeMerged, Repository: "novox/a", Number: 9, Head: strings.Repeat("e", 40),
+	msg := forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: "novox/a", Number: 9, Head: strings.Repeat("e", 40),
 		Merge: strings.Repeat("f", 40), Root: "r"}
-	body, err := sdk.EncodeForge(msg)
+	body, err := forgemsg.EncodeForge(msg)
 	if err != nil {
 		t.Fatalf("a merged message with no trees is refused: %v", err)
 	}
@@ -251,6 +251,17 @@ func TestAMergedGroupEndsMergedWithSourceMainMoved(t *testing.T) {
 	if len(w.h.refusals) != 0 {
 		t.Errorf("the gate refused a merged message with no trees: %v", w.h.refusals)
 	}
+	// A group's end is the indexer's: the gate ignores it before decoding, and says no refusal (1585/T25).
+	w.h.Forged("mesh-delivery-forge-bridge.forge.group.merged", []byte(`{"v":1,"group":"feat/y"}`))
+	if len(w.h.refusals) != 0 {
+		t.Errorf("the gate refused a group's end: %v", w.h.refusals)
+	}
+	// The repository forge/group's merged message ends the same way: it is decoded as a forge message, and this one,
+	// which is none, is refused.
+	w.h.Forged("mesh-delivery-forge-bridge.forge.forge.group.merged", []byte(`{"v":1,"group":"feat/y"}`))
+	if len(w.h.refusals) != 1 {
+		t.Errorf("forge/group's merged message was passed by as a group's end: refusals %v", w.h.refusals)
+	}
 }
 
 // ADR 0419 §2, issue 978: a description's `after:` line is not read, and says so once on its pull request. The

modules/mesh-delivery-gate/cmd/mesh-delivery-gate/issue1275_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 	"time"
 
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/asks"
 	sdk "git.novox.be/novox/mesh-sdk/go/delivery"
 )
@@ -765,6 +766,6 @@ func allGreenFor(w *world, ms ...member) {
 
 // bridgeMerged is the forge bridge's word that it merged a member.
 func bridgeMerged(w *world, repository string, number int, head, merge string) {
-	w.merges.say(sdk.Forge{Kind: sdk.ForgeMerged, Repository: repository, Number: number, Head: head, Merge: merge, Root: "root",
+	w.merges.say(forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: repository, Number: number, Head: head, Merge: merge, Root: "root",
 		Trees: map[string]string{"app": "tree"}})
 }

modules/mesh-delivery-gate/cmd/mesh-delivery-gate/issue1348_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 	"time"
 
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	"git.novox.be/novox/mesh-sdk/go/asks"
 	sdk "git.novox.be/novox/mesh-sdk/go/delivery"
 )
@@ -100,7 +101,7 @@ func TestAnAnswerHandsTheFirstMemberOnlyAndTheBridgesMergedHandsTheNext(t *testi
 	if len(w.merges.puts) != 1 {
 		t.Fatalf("the next member was handed before the bridge said the first merged: %d merges written", len(w.merges.puts))
 	}
-	w.merges.say(sdk.Forge{Kind: sdk.ForgeMerged, Repository: gCat, Number: 2, Head: gHk, Merge: strings.Repeat("a", 40), Root: "r", Trees: map[string]string{"x": "t"}})
+	w.merges.say(forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: gCat, Number: 2, Head: gHk, Merge: strings.Repeat("a", 40), Root: "r", Trees: map[string]string{"x": "t"}})
 	w.settleAll()
 	if len(w.merges.puts) != 2 {
 		t.Fatalf("the second member was not handed after the first merged: %d merges written", len(w.merges.puts))
@@ -115,7 +116,7 @@ func TestAnAnswerHandsTheFirstMemberOnlyAndTheBridgesMergedHandsTheNext(t *testi
 // AC2: the bridge's refused hands no member, and the group is said urgent, naming the member and the forge's words.
 func TestTheBridgesRefusalHandsNoMemberAndIsSaidUrgent(t *testing.T) {
 	w := answeredFirst(t)
-	w.merges.say(sdk.Forge{Kind: sdk.ForgeRefused, Repository: gCat, Number: 2, Head: gHk, Act: "merge",
+	w.merges.say(forgemsg.Forge{Kind: forgemsg.ForgeRefused, Repository: gCat, Number: 2, Head: gHk, Act: "merge",
 		Words: "the forge refused gitea_merge_pull_request: mesh/repo-check (missing)"})
 	w.later(time30s)
 	w.settleAll()
@@ -137,7 +138,7 @@ func TestTheBridgesRefusalHandsNoMemberAndIsSaidUrgent(t *testing.T) {
 // the group, even after the first member merged.
 func TestTheNextMemberIsNotHandedWhileARequiredStatusOfTheGroupIsNotASuccess(t *testing.T) {
 	w := answeredFirst(t)
-	w.merges.say(sdk.Forge{Kind: sdk.ForgeMerged, Repository: gCat, Number: 2, Head: gHk, Merge: strings.Repeat("a", 40), Root: "r", Trees: map[string]string{"x": "t"}})
+	w.merges.say(forgemsg.Forge{Kind: forgemsg.ForgeMerged, Repository: gCat, Number: 2, Head: gHk, Merge: strings.Repeat("a", 40), Root: "r", Trees: map[string]string{"x": "t"}})
 	setChecks(w, gCtl, gHc, "success", "") // the second member's repository check went missing meanwhile
 	w.settleAll()
 	if len(w.merges.puts) != 1 {
@@ -193,7 +194,7 @@ func TestARefusalThatRepeatsWithNoTrunkMoveIsNotAskedAgainWithoutEnd(t *testing.
 	w := answeredFirst(t)
 	d := w.h.deliveries[IDOf(gCat, gHk)]
 	refuse := func(took string) {
-		w.h.ForgeRefused(sdk.Forge{Kind: sdk.ForgeRefused, Repository: gCat, Number: 2, Head: gHk, Act: "merge",
+		w.h.ForgeRefused(forgemsg.Forge{Kind: forgemsg.ForgeRefused, Repository: gCat, Number: 2, Head: gHk, Act: "merge",
 			Words: "novox/mesh-catalog#2 is not merged: its verdict names no trunk commit it was judged against, and main is now f70a99dbf485. " +
 				"The check of head d2d2d2d2d2d2 merged into trunk f70a99dbf485 was asked; the last check took " + took + ". Ask again once both statuses pass"})
 	}

modules/mesh-delivery-gate/cmd/mesh-delivery-gate/merges.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"time"
 
+	"git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg"
 	stdio "git.novox.be/novox/mesh-sdk/go"
 	sdk "git.novox.be/novox/mesh-sdk/go/delivery"
 )
@@ -312,23 +313,33 @@ func (h *Holder) mergeValue(name, key string, approved map[string]string, target
 	return m, len(m.Pulls) > 0 && state == sdk.MergeMerged
 }
 
+// forgeGroupEnd is the whole event of a group's end on FORGE, the forge bridge's event name under its module: compared
+// exactly, so the merged message of a repository named forge/group, which ends the same way, is read as one.
+const forgeGroupEnd = sdk.ForgeBridgeModule + "." + forgemsg.ForgeGroupEndEvent
+
 // Forged takes a message of the forge bridge on FORGE: the gate follows a merge and the refusal of a merge, and nothing else.
+//
+// The end of a group's merges (`forge.group.merged`, a body this gate has no use for: the gate wrote the merges itself) is
+// the indexer's, and is ignored before it is decoded, so no refusal is said for it (issue 1585, ADR 0633 clause 4).
 func (h *Holder) Forged(event string, body []byte) {
-	f, err := sdk.DecodeForge(body)
+	if event == forgeGroupEnd {
+		return
+	}
+	f, err := forgemsg.DecodeForge(body)
 	if err != nil {
 		h.Refuse(fmt.Errorf("a message of the forge bridge is not readable: %v", err))
 		return
 	}
 	switch {
-	case f.Kind == sdk.ForgeMerged:
+	case f.Kind == forgemsg.ForgeMerged:
 		h.ForgeMerged(f)
-	case f.Kind == sdk.ForgeRefused && f.Act == "merge":
+	case f.Kind == forgemsg.ForgeRefused && f.Act == "merge":
 		h.ForgeRefused(f)
 	}
 }
 
 // memberOfForge is the delivery a forge message is about: at the head it names.
-func (h *Holder) memberOfForge(f sdk.Forge) *Delivery {
+func (h *Holder) memberOfForge(f forgemsg.Forge) *Delivery {
 	if d := h.deliveries[IDOf(f.Repository, f.Head)]; d != nil && d.Number == f.Number {
 		return d
 	}
@@ -337,7 +348,7 @@ func (h *Holder) memberOfForge(f sdk.Forge) *Delivery {
 
 // ForgeMerged takes the bridge's word that a pull request the gate handed to it merged: the merge is announced once,
 // with the ask, its asker the teller and the heads (issue 1025), and the next member's turn comes at the next look.
-func (h *Holder) ForgeMerged(f sdk.Forge) {
+func (h *Holder) ForgeMerged(f forgemsg.Forge) {
 	h.mu.Lock()
 	defer h.mu.Unlock()
 	d := h.memberOfForge(f)
@@ -354,7 +365,7 @@ func (h *Holder) ForgeMerged(f sdk.Forge) {
 // ForgeRefused takes the bridge's word that the forge refused a merge: nothing after it is merged, and the refusal is said
 // as a stalled line (ADR 0441 §3, §4). The merge is handed again only at the next event that decides whether it may
 // merge (mergeAgainNow).
-func (h *Holder) ForgeRefused(f sdk.Forge) {
+func (h *Holder) ForgeRefused(f forgemsg.Forge) {
 	h.mu.Lock()
 	defer h.mu.Unlock()
 	d := h.memberOfForge(f)

modules/mesh-delivery-gate/go.mod

@@ -3,7 +3,8 @@ module mesh-delivery-gate
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103174208-b7abe203a929
+	git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg v0.0.0-20261104235927-c78941e80b59
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )

modules/mesh-delivery-gate/go.sum

@@ -1,5 +1,7 @@
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103174208-b7abe203a929 h1:RtAFbUJRP1qO9AIMM2ue+cXNzqj7WZ7IOlSqNvttwuU=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261103174208-b7abe203a929/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg v0.0.0-20261104235927-c78941e80b59 h1:pFb+lP0FxS3bF6N3gHKtjzyixI9b1vC/NLViT/lVzRQ=
+git.novox.be/novox/mesh-delivery/modules/mesh-delivery-forge-bridge/forgemsg v0.0.0-20261104235927-c78941e80b59/go.mod h1:Xxg9VI4y755tznAS2PygQFe2V3/aIzjRn3/06+Br9nQ=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659 h1:tK7MzxVm/ECNg1Yblhh1ynVEthbZCg2mSPW0wQZC0b0=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261104002338-5a38a1221659/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=

modules/mesh-knowledge/README.md

@@ -16,7 +16,7 @@ operator, it is accepted only on the operator's Approve, given on a channel that
 | Verb | Takes | Answers |
 |---|---|---|
 | `ask` | `question` (at most 500 characters), `bound` | the records and clauses bearing on the question, ranked; each clause says whether it holds, what changed it, or that it is only drafted; each record says what changed it since and how to read its reasoning |
-| `get` | `number`, `kind`, `reasoning`, `section`, `version`, `bound` | one record: clauses, links both ways, what changed it since, versions, reviews, the operator's ask; its reasoning only when asked |
+| `get` | `number`, `kind`, `reasoning`, `section`, `version`, `bound` | one record: clauses, links both ways, what changed it since, versions, reviews, the pending version's reviews with their findings (`pending-reviews`), the operator's ask; its reasoning only when asked |
 | `list` | `kind`, `status`, `topic`, `flag` (`research-done` or `proposed-old`), `before` (a number, the cursor), `limit` | short rows, newest first, number by number: number, kind, title, status, topic, date, versions, and whether a proposal is pending; `next`, the `before` that reads on, when more match |
 | `findings` | `number` (optional) | the whole-set findings kept — each a rule's failure, the records it names, what it says, and when; with `number`, only the findings naming that record |
 | `holds` | `topic` or `number`, `bound` | the clauses in force for a topic of the reading order or for one record; never a drafted clause |

modules/mesh-knowledge/cmd/mesh-knowledge/active_effort_test.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"context"
+	"fmt"
 	"strings"
 	"testing"
 	"time"
@@ -118,6 +120,33 @@ func TestAChangesVerdictLeavesTheServedVersionServedAndGraduatingNeedsABecameLin
 		e.Current.Status != StatusActive || e.Current.Section("01-findings.md") != "" {
 		t.Fatalf("after changes: pending %v, current %+v", e.Pending != nil, e.Current.Sections)
 	}
+	// 1970/AC1: get with no version shows the pending version's findings, and says where the version stands.
+	g, err := w.k.Get(GetAsk{Kind: KindResearch, Number: r.Number})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(g.PendingReviews) != 1 || g.PendingReviews[0].Verdict != VerdictChanges || g.PendingReviews[0].Version == 0 ||
+		!strings.Contains(g.PendingReviews[0].Findings, "say where the finding comes from") || len(g.Reviews) != 1 ||
+		!strings.Contains(g.Pending, "changes asked") || !strings.Contains(g.Pending, "pending-reviews") {
+		t.Fatalf("pending findings not shown: %+v, pending %q, reviews %+v", g.PendingReviews, g.Pending, g.Reviews)
+	}
+	// 1970/AC3: under a small bound the last pending review is kept, and the cut is said.
+	e2 := mustGet(t, w.k.Store, key)
+	more := e2.Pending.Clone()
+	for i := 0; i < 3; i++ {
+		more.Reviews = append(more.Reviews, Review{By: "r", Verdict: VerdictChanges, Version: 9, Findings: strings.Repeat("a long finding ", 60) + fmt.Sprint(i)})
+	}
+	if err := w.k.Store.Save(context.Background(), Version{By: "author@g14", Why: "test", Record: more}, false, false, e2.Revision); err != nil {
+		t.Fatal(err)
+	}
+	g, err = w.k.Get(GetAsk{Kind: KindResearch, Number: r.Number, Bound: LeastBound})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(g.PendingReviews) != 1 || !strings.HasSuffix(g.PendingReviews[0].Findings, "2") ||
+		!strings.Contains(g.Cut, "earlier pending review") {
+		t.Fatalf("pending cut: %d kept, cut %q", len(g.PendingReviews), g.Cut)
+	}
 	grad := effortAsk(r.Number, StatusGraduated, overview)
 	if _, err := w.k.Propose("author@g14", grad); err == nil || !strings.Contains(err.Error(), "became") {
 		t.Fatalf("graduated without a became link: %v", err)

modules/mesh-knowledge/cmd/mesh-knowledge/answers.go

@@ -312,14 +312,17 @@ type Got struct {
 	Idea    string `json:"idea,omitempty"`
 	Waiting string `json:"waiting,omitempty"`
 	// Retracted are the retractions the operator approved; Retracting, one waiting for the operator.
-	Retracted   []RetractionRow `json:"retracted,omitempty"`
-	Retracting  string          `json:"retracting,omitempty"`
-	Reviews     []Review        `json:"reviews,omitempty"`
-	Drafting    *Drafting       `json:"drafting,omitempty"`
-	Review      string          `json:"review,omitempty"`
-	Source      string          `json:"source,omitempty"`
-	Reserved    string          `json:"reserved,omitempty"`
-	NeedsOperat bool            `json:"needs-operator,omitempty"`
+	Retracted  []RetractionRow `json:"retracted,omitempty"`
+	Retracting string          `json:"retracting,omitempty"`
+	Reviews    []Review        `json:"reviews,omitempty"`
+	// PendingReviews are the reviews of the pending version, with their findings, when get is asked without a
+	// version (issue 1970): the version waits for its author, and these are what it must answer.
+	PendingReviews []Review  `json:"pending-reviews,omitempty"`
+	Drafting       *Drafting `json:"drafting,omitempty"`
+	Review         string    `json:"review,omitempty"`
+	Source         string    `json:"source,omitempty"`
+	Reserved       string    `json:"reserved,omitempty"`
+	NeedsOperat    bool      `json:"needs-operator,omitempty"`
 	// Brief is what the operator's ask shows of it (issue 639).
 	Brief *Brief `json:"brief,omitempty"`
 	Cut   string `json:"cut,omitempty"`
@@ -371,7 +374,17 @@ func (k *KB) Get(a GetAsk) (*Got, error) {
 		g.Idea = "an idea: research it again before anything rests on it"
 	}
 	if e.Pending != nil && a.Version == 0 {
+		g.PendingReviews = e.Pending.Reviews
 		g.Pending = fmt.Sprintf("version %d, a progressive insight or a new version of an active effort, waits for its review: history shows what it changes", e.PendingVersion)
+		if n := len(e.Pending.Reviews); n > 0 && e.Pending.Reviews[n-1].Verdict == VerdictChanges {
+			last := e.Pending.Reviews[n-1]
+			k := len(strings.Split(strings.TrimSpace(last.Findings), "\n"))
+			if strings.TrimSpace(last.Findings) == "" {
+				k = 0
+			}
+			g.Pending = fmt.Sprintf("version %d: changes asked (%d finding(s)) on version %d, shown in pending-reviews; it waits for its author's revision",
+				e.PendingVersion, k, last.Version)
+		}
 	}
 	if r.Ask != nil {
 		g.Waiting = "the operator's ask: " + r.Ask.Said
@@ -452,6 +465,10 @@ func (k *KB) Get(a GetAsk) (*Got, error) {
 		cut = append(cut, fmt.Sprintf("%d earlier review(s) are not shown: history lists every version", len(g.Reviews)-1))
 		g.Reviews = g.Reviews[len(g.Reviews)-1:]
 	}
+	if size(g) > room && len(g.PendingReviews) > 1 {
+		cut = append(cut, fmt.Sprintf("%d earlier pending review(s) are not shown: get with the pending version's number shows them", len(g.PendingReviews)-1))
+		g.PendingReviews = g.PendingReviews[len(g.PendingReviews)-1:]
+	}
 	for _, which := range []string{"linked-from", "links"} {
 		if size(g) <= room {
 			break

modules/mesh-knowledge/cmd/mesh-knowledge/main.go

@@ -783,7 +783,7 @@ func Tools(k *KB, caller func(map[string]any) string) []stdio.Tool {
 			}},
 		{Name: Seat + ".get",
 			Description: "One record by its number: its title, status, topic, date and deciders; its clauses, each with whether it holds; " +
-				"its links both ways; what changed it since; its versions; its reviews, and the operator's ask when it waits for one. " +
+				"its links both ways; what changed it since; its versions; its reviews, and the findings of the pending version's reviews (pending-reviews) when one waits for its author; the operator's ask when it waits for one. " +
 				"Its reasoning (context, options, consequences, how it is checked; a research effort's documents) only with reasoning, " +
 				"or one section by name; an earlier version with version. Within a bound it states, 4 KiB unless asked for more, " +
 				"saying what it cut.",

modules/mesh-knowledge/cmd/mesh-knowledge/review_test.go

@@ -361,6 +361,15 @@ func TestAnAcceptedRecordChangesOnlyByAnInsightReviewedLikeAProposal(t *testing.
 		e.Pending.Reviews[0].Verdict != VerdictChanges {
 		t.Fatalf("the insight was served before its review approved it: %+v", e.Current.Sections)
 	}
+	// 1970/AC2: the same for a pending insight.
+	g, err := w.k.Get(GetAsk{Kind: KindDecision, Number: n})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(g.PendingReviews) != 1 || !strings.Contains(g.PendingReviews[0].Findings, "what a minute is measured from") ||
+		!strings.Contains(g.Pending, "changes asked") {
+		t.Fatalf("pending insight findings not shown: %+v, %q", g.PendingReviews, g.Pending)
+	}
 	w.judge.review = ""
 	p.Sections[2].Text = "Merges land sooner, by about a minute from the last merge."
 	if _, err := w.k.Propose("author@g14", p); err != nil {

modules/mesh-vault/cmd/mesh-vault/main.go

@@ -302,9 +302,20 @@ func readPlanRaw(key string) ([]byte, error) {
 // assignmentKeys is every key of the controller's assignments mirror, read the same way.
 func assignmentKeys() ([]string, error) { return stdio.State(AssignmentsRead).Keys() }
 
+// Checked by TestTheVaultWholeRotatesANodesLoginWithAStandInEngine: the race it met (a pass before Serve, every watch
+// refused, the rotation waiting for the minute's pass) is what this closes.
+// afterServed runs f once served is closed, that is once stdio.Serve holds the runtime's channel: every function of the
+// bus refuses before that ("before Serve"), and a watch refused then waits for the minute's pass.
+func afterServed(served <-chan struct{}, f func()) {
+	go func() {
+		<-served
+		f()
+	}()
+}
+
 func main() {
 	env := build()
-	go func() {
+	afterServed(stdio.Served(), func() {
 		tick := time.NewTicker(time.Minute)
 		defer tick.Stop()
 		// At start, every covered account it holds whose hash is not of its current generation (ADR 0547 clause 9).
@@ -361,7 +372,7 @@ func main() {
 			}
 			<-tick.C
 		}
-	}()
+	})
 	if err := stdio.Serve("", tools(env)); err != nil {
 		say("%v", err)
 		os.Exit(1)

modules/messenger/cmd/messenger/asks.go

@@ -1416,3 +1416,76 @@ func (h *Holder) AsksNow() []AskView {
 	})
 	return out
 }
+
+// AsksQuery narrows what the tool `operator-channel.asks` answers (issue 595): Key one ask, State open (open and held) or
+// ended, Since the asks opened at or after that time, Bound the most bytes of the answer's asks. The zero query keeps the
+// whole answer, as before.
+type AsksQuery struct {
+	Key, State string
+	Since      time.Time
+	Bound      int
+}
+
+// AsksAnswer is the answer of a narrowed query: the asks kept, how many the filters matched, and, when the bound cut the
+// answer short, that it did and how.
+type AsksAnswer struct {
+	Asks    []AskView `json:"asks"`
+	Matched int       `json:"matched"`
+	Cut     string    `json:"cut,omitempty"`
+}
+
+// AsksQueryOf reads the arguments of the tool; an empty set is the zero query.
+func AsksQueryOf(a map[string]any) (AsksQuery, error) {
+	q := AsksQuery{Key: strArg(a, "key"), State: strArg(a, "state")}
+	if q.State != "" && q.State != "open" && q.State != "ended" {
+		return q, errorf("state is open or ended, not %q", q.State)
+	}
+	if since := strArg(a, "since"); since != "" {
+		t, err := time.Parse(time.RFC3339, since)
+		if err != nil {
+			return q, errorf("since is a time like 2026-11-04T22:00:00Z: %v", err)
+		}
+		q.Since = t
+	}
+	if v, ok := a["bound"].(float64); ok {
+		if v < 1 {
+			return q, errorf("bound is the most bytes of the answer, at least 1")
+		}
+		q.Bound = int(v)
+	}
+	return q, nil
+}
+
+// Narrow keeps of the views (open first, newest first) the asks the query names, and cuts the answer at its byte bound: the
+// asks that fit, in order, and a said cut when one more did not.
+func (q AsksQuery) Narrow(all []AskView) AsksAnswer {
+	var out AsksAnswer
+	out.Asks = []AskView{}
+	var kept []AskView
+	for _, v := range all {
+		open := v.State == StateOpen || v.State == StateHeld
+		switch {
+		case q.Key != "" && v.Key != q.Key,
+			q.State == "open" && !open,
+			q.State == "ended" && open,
+			!q.Since.IsZero() && v.Opened < q.Since.UTC().Format(time.RFC3339):
+			continue
+		}
+		kept = append(kept, v)
+	}
+	out.Matched = len(kept)
+	used := 0
+	for i, v := range kept {
+		if q.Bound > 0 {
+			raw, _ := json.Marshal(v)
+			if used+len(raw)+1 > q.Bound {
+				out.Cut = fmt.Sprintf("the answer is cut at its bound of %d bytes: %d of %d asks are shown, the %d after them are not "+
+					"(narrow with key, state or since, or raise bound)", q.Bound, i, len(kept), len(kept)-i)
+				break
+			}
+			used += len(raw) + 1
+		}
+		out.Asks = append(out.Asks, v)
+	}
+	return out
+}

modules/messenger/cmd/messenger/held_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/json"
+	"reflect"
 	"strings"
 	"testing"
 	"time"
@@ -140,3 +141,55 @@ func TestAHeldAskNamesEveryKindAndWhyWhenNoChannelIsReady(t *testing.T) {
 		t.Fatalf("%q", why)
 	}
 }
+
+// Issue 595: operator-channel.asks answers one ask, the open or the ended, those opened from a time, and no more bytes than a
+// bound, said when it cut the answer short; with no argument it keeps the whole answer.
+func TestTheAsksVerbNarrowsItsAnswer(t *testing.T) {
+	view := func(key, state, opened string) AskView {
+		return AskView{Key: key, Asker: "mesh-delivery", Headline: "Approve " + key, State: state, Opened: opened}
+	}
+	all := []AskView{view("a.3", StateOpen, "2026-11-04T10:00:00Z"), view("a.2", StateHeld, "2026-11-03T10:00:00Z"),
+		view("a.1", "ended", "2026-11-02T10:00:00Z"), view("a.0", "ended", "2026-11-01T10:00:00Z")}
+	one, _ := json.Marshal(all[0])
+	for _, tc := range []struct {
+		name    string
+		args    map[string]any
+		want    []string
+		matched int
+		cut     bool
+		err     bool
+	}{
+		{"no argument is the zero query", map[string]any{}, nil, 0, false, false},
+		{"key", map[string]any{"key": "a.1"}, []string{"a.1"}, 1, false, false},
+		{"state open takes open and held", map[string]any{"state": "open"}, []string{"a.3", "a.2"}, 2, false, false},
+		{"state ended", map[string]any{"state": "ended"}, []string{"a.1", "a.0"}, 2, false, false},
+		{"since", map[string]any{"since": "2026-11-02T12:00:00Z"}, []string{"a.3", "a.2"}, 2, false, false},
+		{"bound cuts and says so", map[string]any{"bound": float64(2*len(one) + 10), "state": "open"}, []string{"a.3", "a.2"}, 2, false, false},
+		{"a bound under the asks cuts", map[string]any{"bound": float64(len(one) + 5)}, []string{"a.3"}, 4, true, false},
+		{"a state that is neither", map[string]any{"state": "done"}, nil, 0, false, true},
+		{"a time that is not one", map[string]any{"since": "yesterday"}, nil, 0, false, true},
+	} {
+		q, err := AsksQueryOf(tc.args)
+		if (err != nil) != tc.err {
+			t.Errorf("%s: err = %v", tc.name, err)
+			continue
+		}
+		if tc.err {
+			continue
+		}
+		if tc.want == nil {
+			if q != (AsksQuery{}) {
+				t.Errorf("%s: %+v is not the zero query, which keeps today's answer", tc.name, q)
+			}
+			continue
+		}
+		got := q.Narrow(all)
+		var keys []string
+		for _, v := range got.Asks {
+			keys = append(keys, v.Key)
+		}
+		if !reflect.DeepEqual(keys, tc.want) || got.Matched != tc.matched || (got.Cut != "") != tc.cut {
+			t.Errorf("%s: asks %v matched %d cut %q, want %v, %d, cut %v", tc.name, keys, got.Matched, got.Cut, tc.want, tc.matched, tc.cut)
+		}
+	}
+}

modules/messenger/cmd/messenger/main.go

@@ -734,8 +734,24 @@ func tools(h *Holder, l *listening) []stdio.Tool {
 		{Name: "operator-channel.asks",
 			Description: "The asks this router holds (novox/hq ADR 0259): open (or held, with since when and why no channel can carry it yet) first, then the last month's — each " +
 				"one's asker, headline, state, when it opened and expires, the channels it was offered on, how it " +
-				"ended (the warrant: who chose what, through which channel), and whether its asker was told.",
-			Run: func(map[string]any) (any, error) { return h.AsksNow(), nil }},
+				"ended (the warrant: who chose what, through which channel), and whether its asker was told. With no argument every " +
+				"ask, which is large; filter it: key for one ask, state open or ended, since (a time, RFC 3339) for the asks opened " +
+				"from then, and bound, the most bytes of the answer, which says when it cut it short.",
+			Input: map[string]any{
+				"key":   str("one ask, by its key (asker.id); none for every ask"),
+				"state": str("open (open and held) or ended; none for both"),
+				"since": str("only the asks opened at or after this time, RFC 3339"),
+				"bound": map[string]any{"type": "integer", "description": "the most bytes of the asks in the answer; said when it cuts the answer short"}},
+			Run: func(a map[string]any) (any, error) {
+				q, err := AsksQueryOf(a)
+				if err != nil {
+					return nil, err
+				}
+				if q == (AsksQuery{}) {
+					return h.AsksNow(), nil
+				}
+				return q.Narrow(h.AsksNow()), nil
+			}},
 		{Name: "messenger_identities",
 			Description: "The accounts linked as the operator, one per channel kind: the account, the name its " +
 				"service shows, when it was linked, and from when it can approve (an hour after linking).",

modules/nfs-server/cmd/nfs-server/machine.go

@@ -105,9 +105,11 @@ type Machine struct {
 	// ownerOf reads a file's owner from its inode; nil is the inode as the kernel says it. Tests set it
 	// so the folders they make stand for a non-root owner, whoever runs them.
 	ownerOf func(info os.FileInfo) (uid, gid int)
-	// clean is when a look below each real path last found no backup repository (LookKept).
-	clean   map[string]time.Time
-	cleanMu sync.Mutex
+	// Beside runs a look below a share beside the pass; nil is a goroutine. Tests run it in place.
+	Beside func(func())
+	// looks is the last look below each real path (LookKept).
+	looks   map[string]*lookBelow
+	looksMu sync.Mutex
 	// walk is the running pass's context, which ends the look below a share when the process stops.
 	walk   context.Context
 	walkMu sync.Mutex

modules/nfs-server/cmd/nfs-server/nfs_test.go

@@ -32,7 +32,7 @@ func newFake(t *testing.T) *fake {
 }
 
 func (f *fake) machine() *Machine {
-	return &Machine{Root: f.root, UID: f.uid, owners: f.owners, ownerOf: asTheLibrarysOwner, Now: func() time.Time { return f.now }, Run: func(_ context.Context, name string, args ...string) Ran {
+	return &Machine{Root: f.root, UID: f.uid, owners: f.owners, ownerOf: asTheLibrarysOwner, Beside: func(f func()) { f() }, Now: func() time.Time { return f.now }, Run: func(_ context.Context, name string, args ...string) Ran {
 		line := strings.Join(append([]string{name}, args...), " ")
 		f.ran = append(f.ran, line)
 		if (line == "exportfs -ra" || line == "sudo -n exportfs -ra") && f.onExportfs != nil {

modules/nfs-server/cmd/nfs-server/process.go

@@ -61,9 +61,8 @@ func (m *Machine) Pass(ctx context.Context, last *Status) Status {
 	if _, note := m.Backup(); note != "" {
 		s.Warnings = append(s.Warnings, note)
 	}
-	m.setWalk(ctx)
+	m.setWalk(ctx) // stays set: a look beside the pass ends when the process does
 	exports, refused, said := m.Judge(c, roster, wants)
-	m.setWalk(nil)
 	if ctx.Err() != nil {
 		// Stopping: write nothing and reload nothing, so Stopped starts at once.
 		s.Problems = append(s.Problems, "the pass was ended by the process stopping; nothing was written")

modules/nfs-server/cmd/nfs-server/review_test.go

@@ -432,3 +432,89 @@ func TestAHangingCommandStillLetsStoppedRemoveTheFileInTime(t *testing.T) {
 		t.Errorf("the export file stays after an unassignment whose commands hung")
 	}
 }
+
+// Issue 1971: the look below a share runs beside the pass. A pass whose walk has not finished still writes
+// its status, refuses the share until a look has finished, keeps believing a clean look while it is renewed,
+// and a walk ended by the process stopping leaves no result.
+func TestTheLookBelowRunsBesideThePassAndNeverHoldsItsStatus(t *testing.T) {
+	f := newFake(t)
+	f.mountinfo("/")
+	f.dir("/srv/clean/films/one")
+	f.file(ConfigFile, grantsConfig("clean=/srv/clean", "clean=ws:rw"))
+	f.roster("ws 10.0.0.3")
+	f.wants(map[string][]Want{"ws": {{Share: "clean", Access: "rw"}}})
+	m := f.machine()
+	var walks []func()
+	m.Beside = func(w func()) { walks = append(walks, w) } // the walk is still running
+	now := time.Date(2026, 11, 5, 5, 0, 0, 0, time.UTC)
+	m.Now = func() time.Time { return now }
+
+	s := m.Pass(context.Background(), nil)
+	if !s.At.Equal(now) || f.read(StatusFile) == "" || len(walks) != 1 {
+		t.Fatalf("the pass waited for the walk: at %v, walks %d", s.At, len(walks))
+	}
+	if !strings.Contains(refusedWhy(s, "clean"), "not been looked through yet") {
+		t.Errorf("a share whose look is unfinished is exported: %+v", s.Refused)
+	}
+	m.Pass(context.Background(), &s)
+	if len(walks) != 1 {
+		t.Errorf("a second walk started while one runs: %d", len(walks))
+	}
+	walks[0]()
+	if s = m.Pass(context.Background(), &s); refusedWhy(s, "clean") != "" {
+		t.Fatalf("the finished look was not used: %+v", s.Refused)
+	}
+
+	now = now.Add(LookKept)
+	s = m.Pass(context.Background(), &s)
+	if len(walks) != 2 || refusedWhy(s, "clean") != "" {
+		t.Errorf("the renewal must run beside the pass and the clean look stand: walks %d, %+v", len(walks), s.Refused)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	m.Pass(ctx, &s)
+	cancel()
+	f.restic("/srv/clean/films/one/backup")
+	walks[1]()
+	if s = m.Pass(context.Background(), &s); refusedWhy(s, "clean") != "" {
+		t.Errorf("a walk ended by the stop left a result: %+v", s.Refused)
+	}
+	walks[len(walks)-1]()
+	if s = m.Pass(context.Background(), &s); !strings.Contains(refusedWhy(s, "clean"), "/srv/clean/films/one/backup") {
+		t.Errorf("the repository was not found by the next look: %+v", s.Refused)
+	}
+}
+
+// After a restart no look is remembered; a share the previous process's export file carries stays exported,
+// and nothing is reloaded, while its first look runs (a delivery never unexports a mounted share).
+func TestARestartKeepsTheExportedShareWhileItsFirstLookRuns(t *testing.T) {
+	f := newFake(t)
+	f.mountinfo("/", "/srv/clean")
+	f.dir("/srv/clean/films/one")
+	f.file(ConfigFile, grantsConfig("clean=/srv/clean", "clean=ws:rw"))
+	f.roster("ws 10.0.0.3")
+	f.wants(map[string][]Want{"ws": {{Share: "clean", Access: "rw"}}})
+	f.kernelReads()
+	first := f.machine()
+	s := first.Pass(context.Background(), nil)
+	before := f.read(ExportFile)
+	if refusedWhy(s, "clean") != "" || !strings.Contains(before, "/srv/clean ") {
+		t.Fatalf("the share was not exported to begin with: %+v %q", s.Refused, before)
+	}
+	m := f.machine()
+	var held []func()
+	m.Beside = func(w func()) { held = append(held, w) }
+	f.ran = nil
+	s = m.Pass(context.Background(), &s)
+	if len(held) != 1 || refusedWhy(s, "clean") != "" || f.read(ExportFile) != before || countExportfs(f.ran) != 0 {
+		t.Errorf("a restart with an unfinished walk unexported the share: %+v, ran %v", s.Refused, f.ran)
+	}
+	// The same name, a new folder holding a repository, the walk unfinished: refused, not carried by name.
+	f.restic("/srv/other/backup")
+	f.file(ConfigFile, grantsConfig("clean=/srv/other", "clean=ws:rw"))
+	m3 := f.machine()
+	m3.Beside = func(func()) {}
+	s = m3.Pass(context.Background(), &s)
+	if refusedWhy(s, "clean") == "" || strings.Contains(f.read(ExportFile), "/srv/other") {
+		t.Errorf("a share moved to a new folder was exported unlooked: %+v", s.Refused)
+	}
+}

modules/nfs-server/cmd/nfs-server/shares.go

@@ -244,33 +244,72 @@ const (
 )
 
 // LookKept is how long a look below a share that found no backup repository is believed. The look walks up
-// to WalkLimit folders, which on a large library is too much for every 30 s pass; a repository put under a
+// to WalkLimit folders, which on a large library takes minutes on a cold disk; a repository put under a
 // share is found within this long. A look that found one, or was cut short, is never kept: the share stays
 // refused and is looked at again on the next pass.
 const LookKept = time.Hour
 
-// repositoryBelow finds a backup repository within WalkDepth levels below dir. complete is false when
-// the look stopped at its bound before it saw everything.
-func (m *Machine) repositoryBelow(dir string) (found string, complete bool) {
-	now := time.Now()
-	if m.Now != nil {
-		now = m.Now()
-	}
-	m.cleanMu.Lock()
-	defer m.cleanMu.Unlock()
-	if at, kept := m.clean[dir]; kept && now.Sub(at) < LookKept {
-		return "", true
-	}
-	found, complete = m.walkBelow(dir)
-	if found == "" && complete {
-		if m.clean == nil {
-			m.clean = map[string]time.Time{}
+// lookBelow is the last look below one folder, and whether another runs now.
+type lookBelow struct {
+	found    string
+	complete bool
+	at       time.Time
+	done     bool // a look has finished; until then there is no result
+	running  bool
+}
+
+// repositoryBelow answers the last look below dir for a backup repository, and starts the next one beside
+// the caller when there is none, or it was not clean, or LookKept has passed. The pass therefore never waits
+// for the walk (issue 1971: a walk of minutes held the status's time back until the module was found
+// unhealthy). pending is true while no look has finished yet; the share is refused until then, and while a
+// kept clean look is being renewed the old result stands. complete is false when the look stopped at its
+// bound or with the process.
+func (m *Machine) repositoryBelow(dir string) (found string, complete, pending bool) {
+	m.looksMu.Lock()
+	r := m.looks[dir]
+	if r == nil {
+		if m.looks == nil {
+			m.looks = map[string]*lookBelow{}
 		}
-		m.clean[dir] = now
-	} else {
-		delete(m.clean, dir)
+		r = &lookBelow{}
+		m.looks[dir] = r
 	}
-	return found, complete
+	fresh := r.done && r.found == "" && r.complete && m.clock().Sub(r.at) < LookKept
+	start := !fresh && !r.running
+	if start {
+		r.running = true
+	}
+	m.looksMu.Unlock()
+	if start {
+		walk := func() {
+			f, c := m.walkBelow(dir)
+			m.looksMu.Lock()
+			defer m.looksMu.Unlock()
+			r.running = false
+			if w := m.walking(); w != nil && w.Err() != nil {
+				return // ended by the process stopping: no result, the old one stands
+			}
+			r.found, r.complete, r.at, r.done = f, c, m.clock(), true
+		}
+		if m.Beside != nil {
+			m.Beside(walk)
+		} else {
+			go walk()
+		}
+	}
+	m.looksMu.Lock()
+	defer m.looksMu.Unlock()
+	if !r.done {
+		return "", false, true
+	}
+	return r.found, r.complete, false
+}
+
+func (m *Machine) clock() time.Time {
+	if m.Now != nil {
+		return m.Now()
+	}
+	return time.Now()
 }
 
 // walkBelow is the look itself, breadth first, bounded by WalkDepth and WalkLimit.
@@ -342,7 +381,8 @@ func (m *Machine) Judge(c Config, roster map[string]string, wants map[string][]W
 		prefix, _ = netip.ParsePrefix(c.Range)
 	}
 	points := m.MountPoints()
-	backup, _ := m.Backup() // judged on every pass, never kept: see backup.go
+	onDisk, _ := m.Read(ExportFile) // what the previous process judged
+	backup, _ := m.Backup()         // judged on every pass, never kept: see backup.go
 	backup.Paths = m.realPaths(backup.Paths)
 	shares := map[string]bool{}
 	for _, s := range c.Shares {
@@ -411,12 +451,16 @@ func (m *Machine) Judge(c Config, roster map[string]string, wants map[string][]W
 			no(fmt.Sprintf("The share %s's folder %s%s is inside the backup repository %s, and backups are never exported.", s.Name, real, via, inside))
 			continue
 		}
-		holds, complete := m.repositoryBelow(real)
+		holds, complete, pending := m.repositoryBelow(real)
 		if holds != "" {
 			no(fmt.Sprintf("The share %s's folder %s%s holds a backup repository (%s), and backups are never exported: share the folders beside it instead.", s.Name, real, via, holds))
 			continue
 		}
-		if !complete {
+		if pending && !carries(onDisk, real) {
+			no(fmt.Sprintf("The share %s's folder %s%s has not been looked through yet for a backup repository (the look runs beside the pass and takes a while on a large folder), so it is not exported yet.", s.Name, real, via))
+			continue
+		}
+		if !pending && !complete {
 			no(fmt.Sprintf("The share %s's folder %s%s holds more folders than the module looks through (%d levels, at most %d folders), so it could not make sure no backup repository is under it: share smaller folders.", s.Name, real, via, WalkDepth, m.limit()))
 			continue
 		}
@@ -487,6 +531,18 @@ func (m *Machine) Judge(c Config, roster map[string]string, wants map[string][]W
 	return out, refused, said
 }
 
+// carries says whether the export file already holds the line for this real folder (a share exported to no
+// node has none and waits for its look; a share whose folder changed is a new folder). While a share's first look is unfinished (after a restart) it stays as the previous process judged
+// it, so a delivery never unexports a share clients have mounted.
+func carries(file, real string) bool {
+	for _, l := range strings.Split(file, "\n") {
+		if strings.HasPrefix(l, real+" ") {
+			return true
+		}
+	}
+	return false
+}
+
 func (m *Machine) limit() int {
 	if m.WalkLimit > 0 {
 		return m.WalkLimit