Merge pull request 'An act's answer is said from one resolution after its write (hq issue 237)' (#253) from fix/237-one-resolution-for-assign into main

cmd/mesh-controller/acts.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"github.com/novox/mesh-controller/internal/broker"
+	"io"
 	"slices"
 	"sort"
 	"strings"
@@ -54,6 +55,9 @@ func assignWith(ctx context.Context, open *stores, node string, opts assignOptio
 	if err := refusedMovingTheController(modules); err != nil {
 		return "", err
 	}
+	// Every line of the answer comes from the one resolution after the write (novox/hq issue 237):
+	// what the reads before it would say about a machine left out is not the answer's.
+	ctx = leftOutSaidBy(ctx, io.Discard)
 	// Held while it is recorded, so it cannot land between a converge's preview and its flip and
 	// be taken without ever having been previewed (novox/hq ADR 0100).
 	ctx, release, err := holdNodes(ctx, open, []string{node})
@@ -125,22 +129,28 @@ func assignWith(ctx context.Context, open *stores, node string, opts assignOptio
 	for _, line := range settled {
 		answer += "\n  " + line
 	}
-	// What this act changed about this node's unmet seat dependencies, and nothing else (novox/hq
-	// ADR 0207): a dependency of a module just assigned, or one this assignment met. The rest of the
-	// node's list, and every other node's, is `status`'s.
-	for _, line := range unheldChange(shelf, node, before, append(append([]string(nil), before...), added...)) {
-		answer += "\n  " + line
-	}
 	// Its bus credential, in the same act (novox/hq issue 203): an assignment pushed before its
 	// credential exists delivers a process that cannot authenticate and crash-loops until somebody
 	// runs a second verb and a second push. Issued here when the module speaks on the bus and has
 	// no credential yet; kept when it has one, so re-assigning rotates nothing.
+	var issued []string
 	for _, module := range added {
 		if line := issueOnAssign(ctx, open, node, module); line != "" {
-			answer += "\n  " + line
+			issued = append(issued, line)
 		}
 	}
-	plan, _, err := planFor(ctx, open, node)
+	// **The one resolution the rest of the answer is said from** (novox/hq issue 237), taken after
+	// the write: what this act changed about this node's unmet seat dependencies, and nothing else
+	// (novox/hq ADR 0207) — a dependency of a module just assigned, or one this assignment met; the
+	// rest of the node's list, and every other node's, is `status`'s — and whether the node resolves.
+	after := resolvedAfter(ctx, open, shelf, node)
+	for _, line := range unheldChangeTo(shelf, node, before, after.modules, after.unheld) {
+		answer += "\n  " + line
+	}
+	for _, line := range issued {
+		answer += "\n  " + line
+	}
+	plan, err := after.plan, after.err
 	if err != nil {
 		// Kept, and still refused. Both halves are the answer, and the rest of the mesh is still
 		// worth reporting: this machine's refusal is rarely the only consequence.
@@ -218,6 +228,8 @@ func unassign(ctx context.Context, open *stores, node string, modules ...string)
 	if len(modules) == 0 {
 		return "", fmt.Errorf("unassign %s names no module", node)
 	}
+	// One resolution after the write, as assign's answer (novox/hq issue 237).
+	ctx = leftOutSaidBy(ctx, io.Discard)
 	ctx, release, err := holdNodes(ctx, open, []string{node})
 	if err != nil {
 		return "", err
@@ -262,15 +274,22 @@ func unassign(ctx context.Context, open *stores, node string, modules ...string)
 	}
 	answer := fmt.Sprintf("%s no longer runs %s — run `push %s` to make it so",
 		node, strings.Join(modules, ", "), node)
-	var left []string
+	after := resolvedAfter(ctx, open, shelf, node)
-	for _, a := range assigned {
+	for _, line := range unheldChangeTo(shelf, node, assigned, after.modules, after.unheld) {
-		if !slices.Contains(modules, a) {
-			left = append(left, a)
-		}
-	}
-	for _, line := range unheldChange(shelf, node, assigned, left) {
 		answer += "\n  " + line
 	}
+	// Whether the node itself still resolves, from the same resolution: before, only the rest of the
+	// mesh's reads said it, on standard error and once per other machine.
+	if after.err != nil {
+		if unresolvable(after.err) {
+			answer += fmt.Sprintf("\n  but %s does not resolve now, so nothing will be sent to it:", node)
+		} else {
+			answer += fmt.Sprintf("\n  but whether %s still resolves could not be read:", node)
+		}
+		for _, line := range strings.Split(strings.TrimRight(after.err.Error(), "\n"), "\n") {
+			answer += "\n    " + strings.TrimSpace(line)
+		}
+	}
 	// What it leaves behind that is irreplaceable is kept and retired, never removed (novox/hq ADR 0233).
 	for _, line := range keptOnUnassign(ctx, open.inventory, node, modules) {
 		answer += "\n  " + line
@@ -278,6 +297,39 @@ func unassign(ctx context.Context, open *stores, node string, modules ...string)
 	return answer + blockedElsewhere(ctx, open, node), nil
 }
 
+// afterAct is the one resolution of a node an act's answer is said from, taken after its write
+// (novox/hq issue 237): the plan or why there is none, the modules it has on the node, and its unmet
+// seat dependencies.
+type afterAct struct {
+	plan    catalogue.Resolution
+	err     error
+	modules []string
+	unheld  []catalogue.Unheld
+}
+
+// resolvedAfter resolves the node as `plan` does, once, after the act's write. When the node resolves,
+// its modules and unmet seat dependencies are the resolution's — the closure, so a holder pulled in by
+// a requirement counts as `plan` counts it. When it does not, they are judged over the assignments read
+// after the write, which can only find more unmet than the closure would: a seat said held there is
+// held in the closure too.
+func resolvedAfter(ctx context.Context, open *stores, shelf map[string]catalogue.Manifest, node string) afterAct {
+	plan, _, err := planFor(ctx, open, node)
+	if err == nil {
+		out := afterAct{plan: plan, unheld: plan.Unheld}
+		for _, m := range plan.Modules {
+			out.modules = append(out.modules, m.Module)
+		}
+		return out
+	}
+	out := afterAct{err: err}
+	assigned, readErr := open.inventory.Assigned(ctx, node)
+	if readErr != nil {
+		return out
+	}
+	out.modules, out.unheld = assigned, unheldOver(shelf, node, assigned)
+	return out
+}
+
 // splitModules is a surface's one `module` field as the modules it names: several, comma-separated,
 // are one act (novox/hq ADR 0207), so the holders that depend on each other go on together from the
 // command API and the controller seat's verbs as they do from the command line.

cmd/mesh-controller/one_resolution_test.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+)
+
+// novox/hq issue 237: every line of an act's answer comes from one resolution of the node taken after
+// its write, so the answer agrees with `plan` for the node right after.
+
+func aProviderAndItsConsumer(t *testing.T, open *stores) {
+	t.Helper()
+	register(t, open, catalogue.Manifest{Module: "db", Version: "1",
+		Provides: []catalogue.Offer{{Name: "rows", Scope: catalogue.ScopeNode}}})
+	register(t, open, catalogue.Manifest{Module: "app", Version: "1", Requires: []string{"rows"}})
+}
+
+// twoRivalsAndANote is a node that does not resolve — two modules claim one node seat there — and a
+// module beside them that changes nothing about it.
+func twoRivalsAndANote(t *testing.T, open *stores) {
+	t.Helper()
+	one, two := rivals()
+	register(t, open, one)
+	register(t, open, two)
+	register(t, open, catalogue.Manifest{Module: "notes", Version: "1"})
+}
+
+func TestAnUnassignThatLeavesItsNodeUnresolvedSaysSoOnceInItsAnswer(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	twoRivalsAndANote(t, open)
+	// Straight into the store, as a node that came to this before the act.
+	for _, m := range []string{"rival-one", "rival-two", "notes"} {
+		if _, err := open.inventory.Assign(ctx, "laptop", m); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	said := answered(t, func() error { return assignCommand(ctx, "unassign", []string{"laptop", "notes"}) })
+
+	if _, _, err := planFor(ctx, open, "laptop"); err == nil || !unresolvable(err) {
+		t.Fatalf("laptop resolves with two claimants of one seat: %v", err)
+	}
+	if n := strings.Count(said, "laptop does not resolve now"); n != 1 {
+		t.Errorf("the answer says laptop does not resolve %d times, want once:\n%s", n, said)
+	}
+	if strings.Contains(said, "is left out of the rest of the mesh") {
+		t.Errorf("the answer carries a line from a read that is not its resolution:\n%s", said)
+	}
+}
+
+func TestAnUnassignThatLeavesItsNodeResolvedSaysNothingOfIt(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	aProviderAndItsConsumer(t, open)
+	if _, err := assign(ctx, open, "laptop", "db", "app"); err != nil {
+		t.Fatal(err)
+	}
+	said, err := unassign(ctx, open, "laptop", "app")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, _, err := planFor(ctx, open, "laptop"); err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(said, "does not resolve") || strings.Contains(said, "could not be read") {
+		t.Errorf("a node that resolves is said not to:\n%s", said)
+	}
+}
+
+func TestAnAssignThatLeavesItsNodeUnresolvedSaysOnlyThePlansRefusal(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	twoRivalsAndANote(t, open)
+	if _, err := assign(ctx, open, "laptop", "rival-one"); err != nil {
+		t.Fatal(err)
+	}
+	// Kept and not resolvable: a second claimant of the seat, which assignment keeps.
+	said, err := assign(ctx, open, "laptop", "rival-two")
+	if err == nil {
+		t.Fatalf("two claimants of one node seat resolved:\n%s", said)
+	}
+	_, _, planErr := planFor(ctx, open, "laptop")
+	if planErr == nil || planErr.Error() != err.Error() {
+		t.Errorf("the act's refusal is not the plan's right after:\nact:  %v\nplan: %v", err, planErr)
+	}
+	if strings.Contains(said, "now has") {
+		t.Errorf("the answer says a seat is now held on a node that does not resolve:\n%s", said)
+	}
+}
+
+// The other readers of the whole mesh still say a machine they leave out, on standard error (novox/hq
+// issue 188); an act sends it elsewhere.
+func TestAMachineLeftOutIsSaidWhereTheContextSays(t *testing.T) {
+	var buf bytes.Buffer
+	sayLeftOut(leftOutSaidBy(context.Background(), &buf), "laptop", errors.New("why"))
+	if buf.String() != "laptop is left out of the rest of the mesh: it does not resolve: why\n" {
+		t.Errorf("said %q", buf.String())
+	}
+	got := answered(t, func() error {
+		sayLeftOut(context.Background(), "laptop", errors.New("why"))
+		return nil
+	})
+	if !strings.Contains(got, "laptop is left out") {
+		t.Errorf("without an act's writer the line did not reach standard error: %q", got)
+	}
+}

cmd/mesh-controller/plan.go

@@ -292,7 +292,7 @@ func theRestOfTheMesh(ctx context.Context, inv *inventory.Inventory,
 		if err != nil {
 			// Said, not skipped: a machine dropped here offers nothing and holds nothing as far
 			// as every other machine's plan can tell (novox/hq issue 188).
-			fmt.Fprintf(os.Stderr, "%s is left out of the rest of the mesh: it does not resolve: %v\n", o.node.Name, err)
+			sayLeftOut(ctx, o.node.Name, err)
 			continue
 		}
 		firstHeld = append(firstHeld, got.Claims...)
@@ -337,7 +337,7 @@ func theRestOfTheMesh(ctx context.Context, inv *inventory.Inventory,
 			// resolved without its offers, and one that consumes them cannot resolve here by
 			// design — that is not the machine being dropped, it is the view being partial.
 			if exclude == "" {
-				fmt.Fprintf(os.Stderr, "%s is left out of the rest of the mesh: it does not resolve: %v\n", o.node.Name, err)
+				sayLeftOut(ctx, o.node.Name, err)
 			}
 			continue
 		}
@@ -347,6 +347,35 @@ func theRestOfTheMesh(ctx context.Context, inv *inventory.Inventory,
 	return world, nil
 }
 
+// leftOutKey carries where theRestOfTheMesh says a machine it leaves out, for an act that answers with
+// its own resolution instead (novox/hq issue 237).
+type leftOutKey struct{}
+
+// leftOutSaidBy is ctx with theRestOfTheMesh's "left out" lines written to w rather than to standard
+// error.
+//
+// **An act's answer is one resolution taken after its write** (novox/hq issue 237, decided 2026-10-11).
+// `assign` read the whole mesh once before its write — to record the seats held by derivation — and that
+// read said, on standard error, that the node did not resolve for lack of the seat the act was about to
+// give it. The controller seat's verb answers with both streams, so the stale line came last, after the
+// act's own "now has it held", and named as its remedy the assignment just made. An act gives io.Discard
+// here: what the node resolves to after the write is said by its own planFor, and every other machine
+// that does not resolve by blockedElsewhere, both read after the write.
+func leftOutSaidBy(ctx context.Context, w io.Writer) context.Context {
+	return context.WithValue(ctx, leftOutKey{}, w)
+}
+
+// sayLeftOut says that a machine is left out of the rest of the mesh, where ctx says to: standard
+// error unless an act said otherwise. Said, not skipped: a machine dropped there offers nothing and
+// holds nothing as far as every other machine's plan can tell (novox/hq issue 188).
+func sayLeftOut(ctx context.Context, node string, err error) {
+	w, ok := ctx.Value(leftOutKey{}).(io.Writer)
+	if !ok {
+		w = os.Stderr
+	}
+	fmt.Fprintf(w, "%s is left out of the rest of the mesh: it does not resolve: %v\n", node, err)
+}
+
 // declarationFor is everything a node would be sent.
 //
 // One place, because there were three and one of them was written before credentials existed and
@@ -1751,28 +1780,43 @@ func (l *unheldLogger) log(node string, unheld []catalogue.Unheld) {
 // which includes every one of a module just assigned — and each now met that was not. Nothing about
 // any other node, and nothing that was already true before the act.
 func unheldChange(shelf map[string]catalogue.Manifest, node string, before, after []string) []string {
-	judge := func(names []string) map[string]catalogue.Unheld {
+	return unheldChangeTo(shelf, node, before, after, unheldOver(shelf, node, after))
-		var set []catalogue.Manifest
+}
-		for _, n := range names {
+
-			if m, known := shelf[n]; known {
+// unheldOver is the node's unmet seat dependencies judged over a set of module names alone.
-				set = append(set, m)
+func unheldOver(shelf map[string]catalogue.Manifest, node string, names []string) []catalogue.Unheld {
-			}
+	var set []catalogue.Manifest
+	for _, n := range names {
+		if m, known := shelf[n]; known {
+			set = append(set, m)
 		}
-		out := map[string]catalogue.Unheld{}
-		for _, u := range catalogue.UnheldDependencies(shelf, node, set, nil) {
-			out[u.Module+" "+u.Seat] = u
-		}
-		return out
 	}
-	was, now := judge(before), judge(after)
+	return catalogue.UnheldDependencies(shelf, node, set, nil)
+}
+
+// unheldChangeTo is unheldChange with the node's dependencies as they now stand given: `now` is what
+// the act's one resolution after its write says is unmet, and `after` the modules that resolution has
+// on the node (novox/hq issue 237). A line about how things stand after the act is never judged from
+// anything else, so it cannot disagree with `plan` for the node.
+func unheldChangeTo(shelf map[string]catalogue.Manifest, node string, before, after []string,
+	now []catalogue.Unheld) []string {
+	key := func(u catalogue.Unheld) string { return u.Module + " " + u.Seat }
+	was := map[string]catalogue.Unheld{}
+	for _, u := range unheldOver(shelf, node, before) {
+		was[key(u)] = u
+	}
+	is := map[string]catalogue.Unheld{}
+	for _, u := range now {
+		is[key(u)] = u
+	}
 	var lines []string
-	for _, k := range sortedNames(now) {
+	for _, k := range sortedNames(is) {
 		if _, already := was[k]; !already {
-			lines = append(lines, "but "+now[k].String())
+			lines = append(lines, "but "+is[k].String())
 		}
 	}
 	for _, k := range sortedNames(was) {
-		if _, still := now[k]; still {
+		if _, still := is[k]; still {
 			continue
 		}
 		u := was[k]

cmd/mesh-controller/replay237_test.go

@@ -0,0 +1,85 @@
+package main
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+)
+
+// TestReplay237 replays novox/hq issue 237 (2026-10-04): a workstation already ran a module that
+// depends on a node seat nothing there held, and the module holding that seat was assigned to it. The
+// answer said the seat was now held, and then that the workstation was left out of the rest of the mesh
+// for lack of it, naming as the remedy the assignment just made. `plan` for the node, right after,
+// resolved. The outcome asserted: every line of the answer, as the controller seat's verb gives it
+// (standard output, then standard error), agrees with `plan` for the node right after the act. Written
+// with only what the controller had before its fix — register, assign's command, planFor — so it is laid
+// over the commit before.
+func TestReplay237(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	register(t, open, aContainer("web"))
+	register(t, open, catalogue.Manifest{Module: "docker", Version: "1",
+		Claims: []catalogue.Claim{{Name: catalogue.ContainerRuntimeSeat, Scope: catalogue.ScopeNode}}})
+	// Already on the node, from before the rule refused it: the node does not resolve until the
+	// holder comes.
+	if _, err := open.inventory.Assign(ctx, "laptop", "web"); err != nil {
+		t.Fatal(err)
+	}
+
+	said := answered(t, func() error { return assignCommand(ctx, "assign", []string{"laptop", "docker"}) })
+
+	if _, _, err := planFor(ctx, open, "laptop"); err != nil {
+		t.Fatalf("laptop does not resolve right after the act: %v\nthe answer was:\n%s", err, said)
+	}
+	if !strings.Contains(said, "web on laptop now has "+catalogue.ContainerRuntimeSeat+" held") {
+		t.Errorf("the answer does not say the seat is now held:\n%s", said)
+	}
+	for _, not := range []string{"laptop is left out", "does not resolve", "which nothing on laptop holds"} {
+		if strings.Contains(said, not) {
+			t.Errorf("the answer says %q, which `plan` right after contradicts:\n%s", not, said)
+		}
+	}
+}
+
+// answered is what a command says as the controller seat's verb answers it: standard output, then
+// standard error (answerOf).
+func answered(t *testing.T, f func() error) string {
+	t.Helper()
+	read := func(w **os.File) (func() string, error) {
+		old := *w
+		r, pw, err := os.Pipe()
+		if err != nil {
+			return nil, err
+		}
+		*w = pw
+		got := make(chan string)
+		go func() {
+			var buf bytes.Buffer
+			_, _ = io.Copy(&buf, r)
+			got <- buf.String()
+		}()
+		return func() string {
+			_ = pw.Close()
+			*w = old
+			return <-got
+		}, nil
+	}
+	stdout, err := read(&os.Stdout)
+	if err != nil {
+		t.Fatal(err)
+	}
+	stderr, err := read(&os.Stderr)
+	if err != nil {
+		t.Fatal(err)
+	}
+	runErr := f()
+	said := stdout() + stderr()
+	if runErr != nil {
+		t.Fatalf("%v\n%s", runErr, said)
+	}
+	return said
+}

testdata/store-tests

@@ -22,3 +22,7 @@
 ./cmd/mesh-controller TestAWalkEndedByCancelOrClearIsSaidEnded
 ./cmd/mesh-controller TestAWalkRestartedByARebuildIsSaidStarted
 ./cmd/mesh-controller TestAWalkStoppedByHandAndRetriedEndsFailedWhenItFailsAgain
+./cmd/mesh-controller TestReplay237
+./cmd/mesh-controller TestAnUnassignThatLeavesItsNodeUnresolvedSaysSoOnceInItsAnswer
+./cmd/mesh-controller TestAnUnassignThatLeavesItsNodeResolvedSaysNothingOfIt
+./cmd/mesh-controller TestAnAssignThatLeavesItsNodeUnresolvedSaysOnlyThePlansRefusal