Merge pull request 'A module's state on the bus: buckets from the catalogue, grants, membership (hq ADR 0201)' (#257) from feat/module-state-on-the-bus into main

internal/catalogue/manifest.go

@@ -325,6 +325,15 @@ type Manifest struct {
 	// person's account (design 25 §7) already had the same shape.
 	Invokes []string `json:"invokes,omitempty"`
 
+	// State is the current state this module keeps on the bus, by local name: each a key-value
+	// bucket the controller creates, which every instance of the module writes and reads
+	// (novox/hq ADR 0201). Not history — that is an event — and never a secret, sealed or not.
+	State []StateDeclaration `json:"state,omitempty"`
+
+	// Reads are other modules' state this module reads and watches, each `<module>.<name>`
+	// (novox/hq ADR 0201). Read-only: only the owner's instances write.
+	Reads []string `json:"reads,omitempty"`
+
 	// Capabilities the machine must have. A different field from Requires because the remedy
 	// differs: a missing module can be assigned, and a missing capability means the wrong
 	// machine.
@@ -1316,6 +1325,8 @@ func ParseManifest(raw []byte) (Manifest, error) {
 	// module whose event names are wrong installs, starts, connects and reacts to nothing, with
 	// every log line saying it is fine (novox/hq 04-ISSUES/127).
 	problems = append(problems, EventProblems(m)...)
+	// And what it may call its state, and whose it may read (state.go, novox/hq ADR 0201).
+	problems = append(problems, StateProblems(m)...)
 	wellFormed := true
 	for _, c := range m.Claims {
 		if !name.MatchString(c.Name) {

internal/catalogue/seats_declared.go

@@ -215,6 +215,13 @@ func CatalogueProblems(shelf Shelf) []string {
 			}
 		}
 	}
+	// A read of a module's state that module does not keep (novox/hq ADR 0201) — said only where the
+	// owner is on the shelf, as a consumer may be installed before its emitter.
+	var manifests []Manifest
+	for _, module := range shelfOrder(shelf) {
+		manifests = append(manifests, shelf[module])
+	}
+	problems = append(problems, StateReadsNothingDeclares(manifests)...)
 	sort.Strings(problems)
 	return problems
 }

internal/catalogue/state.go

@@ -0,0 +1,150 @@
+package catalogue
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+// What a module may call its state, and whose state it may ask to read (novox/hq ADR 0201).
+//
+// A module names its state **locally** — `servers`, never a bucket or a subject — and another
+// module's as `<module>.<name>`, the way a consumed event names its emitter (design 32 §1). The
+// mesh derives the bucket from the two names, so the module and the local name must each be one
+// token: the bucket joins them with an underscore, which neither may contain, so two modules can
+// never derive one bucket.
+
+// stateName is one local name of a module's state: lower-case, no dot, no underscore.
+var stateName = regexp.MustCompile(`^[a-z0-9][a-z0-9-]*$`)
+
+// The mesh's caps on what a module may ask of a bucket's history.
+const (
+	// StateMostHistory is the most past values a key may keep. The server's own limit.
+	StateMostHistory = 64
+)
+
+// StateDeclaration is one bucket a module owns: its local name, and the options that are the
+// owner's to choose, as a seat chooses how long its backlog survives (design 32 §3).
+type StateDeclaration struct {
+	Name string `json:"name"`
+	// History is how many values a key keeps, the current one included; zero is one.
+	History int `json:"history,omitempty"`
+	// TTLSeconds is how long a value lives once written; zero is until it is replaced or deleted.
+	TTLSeconds int `json:"ttl-seconds,omitempty"`
+}
+
+// UnmarshalJSON reads a bucket as its bare name, or as {name, history, ttl-seconds}.
+func (s *StateDeclaration) UnmarshalJSON(raw []byte) error {
+	trimmed := bytes.TrimSpace(raw)
+	if len(trimmed) > 0 && trimmed[0] == '"' {
+		return json.Unmarshal(trimmed, &s.Name)
+	}
+	type plain StateDeclaration
+	var full plain
+	dec := json.NewDecoder(bytes.NewReader(trimmed))
+	dec.DisallowUnknownFields()
+	if err := dec.Decode(&full); err != nil {
+		return fmt.Errorf("a state is either a name or {name, history, ttl-seconds}: %w", err)
+	}
+	*s = StateDeclaration(full)
+	return nil
+}
+
+// MarshalJSON writes back the short form when there is nothing else to say.
+func (s StateDeclaration) MarshalJSON() ([]byte, error) {
+	if s.History == 0 && s.TTLSeconds == 0 {
+		return json.Marshal(s.Name)
+	}
+	type plain StateDeclaration
+	return json.Marshal(plain(s))
+}
+
+// ReadState splits a read into the owning module and the local name, or says why it is not one.
+func ReadState(read string) (module, local string, err error) {
+	at := strings.LastIndex(read, ".")
+	if at <= 0 || at == len(read)-1 {
+		return "", "", fmt.Errorf("%q does not name a module and its state: a read is <module>.<name>", read)
+	}
+	module, local = read[:at], read[at+1:]
+	if !stateName.MatchString(module) {
+		return "", "", fmt.Errorf("%q cannot own state: a module whose state is read is one plain name", module)
+	}
+	if !stateName.MatchString(local) {
+		return "", "", fmt.Errorf("%q is not a state name: lower-case letters, digits and hyphens", local)
+	}
+	return module, local, nil
+}
+
+// StateProblems is what is wrong with a manifest's state and reads.
+//
+// Refused at registration, because a bucket name the bus cannot hold is a module that installs,
+// starts, and is refused on its first write with a reason about a bucket nobody named.
+func StateProblems(m Manifest) []string {
+	var problems []string
+	if len(m.State) > 0 && !stateName.MatchString(m.Module) {
+		problems = append(problems, fmt.Sprintf(
+			"%s keeps state, and a module's name is part of its buckets' names, which take one plain "+
+				"name — no dot (novox/hq ADR 0201)", m.Module))
+	}
+	seen := map[string]bool{}
+	for _, s := range m.State {
+		switch {
+		case !stateName.MatchString(s.Name):
+			problems = append(problems, fmt.Sprintf(
+				"%s keeps state %q: a state is named locally — lower-case letters, digits and hyphens, "+
+					"no dot and no underscore; the mesh derives the bucket (novox/hq ADR 0201)", m.Module, s.Name))
+		case seen[s.Name]:
+			problems = append(problems, fmt.Sprintf("%s keeps state %q twice", m.Module, s.Name))
+		}
+		seen[s.Name] = true
+		if s.History < 0 || s.History > StateMostHistory {
+			problems = append(problems, fmt.Sprintf(
+				"%s keeps %d values of %q; a key keeps between 1 and %d", m.Module, s.History, s.Name, StateMostHistory))
+		}
+		if s.TTLSeconds < 0 {
+			problems = append(problems, fmt.Sprintf("%s gives %q a negative lifetime", m.Module, s.Name))
+		}
+	}
+	for _, r := range m.Reads {
+		module, _, err := ReadState(r)
+		if err != nil {
+			problems = append(problems, fmt.Sprintf("%s reads %v", m.Module, err))
+			continue
+		}
+		if module == m.Module {
+			problems = append(problems, fmt.Sprintf(
+				"%s reads %q, which is its own state: a module reads and writes what it keeps already", m.Module, r))
+		}
+	}
+	return problems
+}
+
+// StateReadsNothingDeclares is every read across a catalogue whose owner is present and declares no
+// such state. An absent owner says nothing — a module may be installed long before the one whose
+// state it reads, as a consumer may before its emitter (design 32 §1).
+func StateReadsNothingDeclares(manifests []Manifest) []string {
+	declared := map[string]map[string]bool{}
+	for _, m := range manifests {
+		own := map[string]bool{}
+		for _, s := range m.State {
+			own[s.Name] = true
+		}
+		declared[m.Module] = own
+	}
+	var problems []string
+	for _, m := range manifests {
+		for _, r := range m.Reads {
+			module, local, err := ReadState(r)
+			if err != nil {
+				continue
+			}
+			if own, present := declared[module]; present && !own[local] {
+				problems = append(problems, fmt.Sprintf(
+					"%s reads %q, and %s keeps no state called %q", m.Module, r, module, local))
+			}
+		}
+	}
+	return problems
+}

internal/catalogue/state_test.go

@@ -0,0 +1,94 @@
+package catalogue
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+// A module declares the state it keeps and the state it reads (novox/hq ADR 0201), a bucket by its
+// bare name or with the owner's options.
+func TestAManifestMaySayWhatStateItKeepsAndReads(t *testing.T) {
+	m, err := ParseManifest([]byte(`{"module":"claude-code","version":"1",` +
+		`"state":["servers",{"name":"seen","history":5,"ttl-seconds":3600}],` +
+		`"reads":["licence-manager.bindings"]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(m.State) != 2 || m.State[0].Name != "servers" || m.State[1].History != 5 || m.State[1].TTLSeconds != 3600 {
+		t.Fatalf("state not read: %+v", m.State)
+	}
+	if len(m.Reads) != 1 || m.Reads[0] != "licence-manager.bindings" {
+		t.Fatalf("reads not read: %v", m.Reads)
+	}
+	// Written back as it came in: the short form where nothing else is said.
+	out, _ := json.Marshal(m.State)
+	if string(out) != `["servers",{"name":"seen","history":5,"ttl-seconds":3600}]` {
+		t.Fatalf("written back as %s", out)
+	}
+}
+
+// A name the bus could not hold, or that would let two modules derive one bucket, is refused at
+// registration in the manifest's words.
+func TestAStateNameIsLocalAndOneToken(t *testing.T) {
+	for _, c := range []struct{ manifest, says string }{
+		{`{"module":"a","version":"1","state":["mesh.servers"]}`, `keeps state "mesh.servers": a state is named locally`},
+		{`{"module":"a","version":"1","state":["my_servers"]}`, `keeps state "my_servers"`},
+		{`{"module":"a","version":"1","state":["s","s"]}`, `keeps state "s" twice`},
+		{`{"module":"a","version":"1","state":[{"name":"s","history":65}]}`, `a key keeps between 1 and 64`},
+		{`{"module":"a.b","version":"1","state":["s"]}`, `no dot`},
+		{`{"module":"a","version":"1","reads":["bindings"]}`, `a read is <module>.<name>`},
+		{`{"module":"a","version":"1","reads":["a.s"]}`, `which is its own state`},
+		{`{"module":"a","version":"1","state":[{"name":"s","shared":true}]}`, `{name, history, ttl-seconds}`},
+	} {
+		_, err := ParseManifest([]byte(c.manifest))
+		if err == nil {
+			t.Errorf("%s was accepted", c.manifest)
+			continue
+		}
+		if !strings.Contains(err.Error(), c.says) {
+			t.Errorf("%s refused for the wrong reason: %v", c.manifest, err)
+		}
+	}
+}
+
+// A read whose owner is present must name a state that owner keeps; an absent owner says nothing,
+// because a module may be installed before the one whose state it reads.
+func TestAReadNamesStateItsOwnerKeeps(t *testing.T) {
+	owner := Manifest{Module: "licence-manager", State: []StateDeclaration{{Name: "bindings"}}}
+	good := Manifest{Module: "claude-code", Reads: []string{"licence-manager.bindings", "absent.anything"}}
+	bad := Manifest{Module: "other", Reads: []string{"licence-manager.tokens"}}
+	if p := StateReadsNothingDeclares([]Manifest{owner, good}); len(p) != 0 {
+		t.Fatalf("a read of declared state was refused: %v", p)
+	}
+	p := StateReadsNothingDeclares([]Manifest{owner, bad})
+	if len(p) != 1 || !strings.Contains(p[0], `licence-manager keeps no state called "tokens"`) {
+		t.Fatalf("a read of state nobody keeps was not named: %v", p)
+	}
+}
+
+// **Across the whole catalogue**: every state name is local, and every read whose owner is present
+// names state that owner keeps.
+func TestEveryManifestsStateIsLocalAndEveryReadIsKept(t *testing.T) {
+	manifests := theCatalogue(t)
+	var problems []string
+	for _, m := range manifests {
+		problems = append(problems, StateProblems(m)...)
+	}
+	problems = append(problems, StateReadsNothingDeclares(manifests)...)
+	if len(problems) > 0 {
+		t.Fatalf("the catalogue's state is not what ADR 0201 says:\n  %s", strings.Join(problems, "\n  "))
+	}
+}
+
+// `module check` says it too: the cross-catalogue pass names a read nothing on the shelf keeps.
+func TestTheCataloguePassNamesAReadItsOwnerDoesNotKeep(t *testing.T) {
+	shelf := Shelf{
+		"licence-manager": {Module: "licence-manager", State: []StateDeclaration{{Name: "bindings"}}},
+		"claude-code":     {Module: "claude-code", Reads: []string{"licence-manager.tokens"}},
+	}
+	problems := CatalogueProblems(shelf)
+	if len(problems) != 1 || !strings.Contains(problems[0], `keeps no state called "tokens"`) {
+		t.Fatalf("the catalogue pass said %v", problems)
+	}
+}