A seat says what it receives, and its holder places every module's contribution (hq ADR 0212)

Each contribution grain was a manifest field and a renderer of its own; a module now contributes
to any seat with a kind that seat receives, the holder places it with
${contribution:<seat>:<kind>}, and the contribution depends on the seat. node-hotkeys is the
first new seat to receive (triggers); the display session receives window-manager config.

internal/catalogue/environment_into.go

@@ -110,6 +110,8 @@ const (
 var (
 	ofEnvironment = regexp.MustCompile(`\$\{environment:([^}]*)\}`)
 	ofShell       = regexp.MustCompile(`\$\{shell:([^}]*)\}`)
+	// ofContributed is either kind of contributed text, matched together so both fill in one pass.
+	ofContributed = regexp.MustCompile(`\$\{(shell|contribution):([^}]*)\}`)
 )
 
 // variableName is a POSIX shell variable name, which is also what environment.d accepts.
@@ -223,6 +225,7 @@ func (m Manifest) contributionPlaceholderProblems() []string {
 	var problems []string
 	for _, r := range m.Resources {
 		problems = append(problems, placeholderProblems(m, r)...)
+		problems = append(problems, seatPlaceholderProblems(m, r)...)
 	}
 	return problems
 }
@@ -545,7 +548,7 @@ func shellCode(modules []Manifest, shell, slot string) string {
 // is filled before the shell's code is, and each is replaced in a single pass over what the holder
 // wrote, so a contributed piece is never scanned again.
 func contributionsInto(resource map[string]any, m Manifest, modules []Manifest, facts map[string]string) error {
-	if problems := placeholderProblems(m, resource); len(problems) > 0 {
+	if problems := append(placeholderProblems(m, resource), seatPlaceholderProblems(m, resource)...); len(problems) > 0 {
 		return fmt.Errorf("%s", problems[0])
 	}
 	content, ok := resource["content"].(string)
@@ -564,10 +567,17 @@ func contributionsInto(resource map[string]any, m Manifest, modules []Manifest,
 			return env.posix()
 		})
 	}
-	if ofShell.MatchString(content) {
-		content = ofShell.ReplaceAllStringFunc(content, func(placeholder string) string {
-			shell, slot, _ := strings.Cut(ofShell.FindStringSubmatch(placeholder)[1], ":")
-			return shellCode(modules, shell, slot)
+	// Shell code and seat contributions in one pass (novox/hq ADR 0212): both are contributed text
+	// the controller does not read, so neither may be scanned after the other is in place — a
+	// contributed line that happened to spell the other's placeholder would be filled.
+	if ofContributed.MatchString(content) {
+		content = ofContributed.ReplaceAllStringFunc(content, func(placeholder string) string {
+			found := ofContributed.FindStringSubmatch(placeholder)
+			first, second, _ := strings.Cut(found[2], ":")
+			if found[1] == "contribution" {
+				return seatContributions(modules, first, second)
+			}
+			return shellCode(modules, first, second)
 		})
 	}
 	resource["content"] = content

internal/catalogue/graphical_session.go

@@ -41,16 +41,20 @@ func graphicalSessionSeats() []Seat {
 					"name":   "the profile to save or apply (save and apply only)",
 				}, []string{"action"}), "action", "list", "save", "apply")},
 		}},
-		{Name: DisplaySessionSeat, Scope: ScopeNode, Decision: decided, Serves: []Verb{
-			{Name: "reload", Description: "Reload the session's configuration in place, keeping its windows.",
-				Input: schema(map[string]string{}, nil)},
-			{Name: "workspaces", Description: "The session's workspaces: each one's name, output, and whether " +
-				"it is visible or focused.",
-				Input: schema(map[string]string{}, nil)},
-			{Name: "windows", Description: "The session's windows: each one's title, class, workspace and " +
-				"whether it has focus; narrowed to one workspace when named.",
-				Input: schema(map[string]string{"workspace": "one workspace (optional)"}, nil)},
-		}},
+		// It receives window-manager configuration lines from every other module (novox/hq ADR 0212):
+		// bindings, start-up commands, rules — placed by the session's holder, never written into
+		// its directory by the contributor.
+		{Name: DisplaySessionSeat, Scope: ScopeNode, Decision: decided,
+			Receives: []Receivable{{Kind: "config", Comment: "#"}}, Serves: []Verb{
+				{Name: "reload", Description: "Reload the session's configuration in place, keeping its windows.",
+					Input: schema(map[string]string{}, nil)},
+				{Name: "workspaces", Description: "The session's workspaces: each one's name, output, and whether " +
+					"it is visible or focused.",
+					Input: schema(map[string]string{}, nil)},
+				{Name: "windows", Description: "The session's windows: each one's title, class, workspace and " +
+					"whether it has focus; narrowed to one workspace when named.",
+					Input: schema(map[string]string{"workspace": "one workspace (optional)"}, nil)},
+			}},
 		{Name: TerminalEmulatorSeat, Scope: ScopeNode, Decision: decided, Serves: []Verb{
 			{Name: "open", Description: "Open a terminal window in the operator's session, running a command " +
 				"or the login shell, in a directory or the account's home.",

internal/catalogue/manifest.go

@@ -539,6 +539,11 @@ type Manifest struct {
 	// the holder of node-login-shell put the slot's placeholder.
 	Shell []ShellCode `json:"shell,omitempty"`
 
+	// Contributions are configuration this module gives the holder of a seat it does not hold, in
+	// that tool's own grammar (novox/hq ADR 0212): a seat, a kind the seat receives, and the text. The
+	// holder places them; the module depends on the seat (ADR 0210 §3).
+	Contributions []SeatContribution `json:"contributions,omitempty"`
+
 	// Guards are ports of this module's the mesh refuses on an adopted node except from the
 	// private network and from the machine itself (novox/hq ADR 0100) — the store's port and the
 	// broker's management port. The ports the software uses; the mesh guards where the machine
@@ -1846,6 +1851,7 @@ func ParseManifest(raw []byte) (Manifest, error) {
 	problems = append(problems, m.environmentProblems()...)
 	problems = append(problems, m.shellProblems()...)
 	problems = append(problems, m.contributionPlaceholderProblems()...)
+	problems = append(problems, m.seatContributionProblems()...)
 
 	for i, r := range m.Resources {
 		id, _ := r["id"].(string)

internal/catalogue/seat_contributions.go

@@ -0,0 +1,156 @@
+package catalogue
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+// A module contributes to a seat it does not hold (novox/hq ADR 0212).
+//
+// ADR 0210 made a tool's configuration its seat holder's, and every other module's way in a
+// contribution to the seat. The environment, the shell's slots and the power moments each became a
+// field of their own; this is the general form, so a new seat that takes contributions is a row in
+// the seat table rather than a change to the manifest: a contribution names a seat, a kind that
+// seat receives, and text in the tool's own grammar, which the controller never reads.
+
+// HotkeysSeat is the machine's hotkey daemon (novox/hq ADR 0212 §5).
+const HotkeysSeat = "node-hotkeys"
+
+// SeatContribution is one piece of configuration a module gives a seat's holder to place.
+type SeatContribution struct {
+	// Seat is the seat whose holder places it.
+	Seat string `json:"seat"`
+	// Kind is which of the seat's receivable kinds it is.
+	Kind string `json:"kind"`
+	// Content is the text, in the tool's own grammar. Never interpreted.
+	Content string `json:"content"`
+}
+
+// ofContribution is where a holder places a kind: ${contribution:<seat>:<kind>}. Loose inside the
+// braces, so a misspelt seat or kind is found and refused rather than written out as text.
+var ofContribution = regexp.MustCompile(`\$\{contribution:([^}]*)\}`)
+
+// receivable is what a seat receives of a kind, with the seat's canonical name; false when the seat
+// is unknown or does not receive it.
+func receivable(seat, kind string) (Seat, Receivable, bool) {
+	s, known := SeatNamed(seat)
+	if !known {
+		return Seat{}, Receivable{}, false
+	}
+	for _, r := range s.Receives {
+		if r.Kind == kind {
+			return s, r, true
+		}
+	}
+	return s, Receivable{}, false
+}
+
+// kindsOf names a seat's receivable kinds for a refusal.
+func kindsOf(s Seat) string {
+	if len(s.Receives) == 0 {
+		return "it receives no contributions"
+	}
+	var kinds []string
+	for _, r := range s.Receives {
+		kinds = append(kinds, r.Kind)
+	}
+	return "it receives " + strings.Join(kinds, ", ")
+}
+
+// seatContributionProblems is what is wrong with this module's contributions, from the manifest
+// alone (novox/hq ADR 0212 §2).
+func (m Manifest) seatContributionProblems() []string {
+	var problems []string
+	for i, c := range m.Contributions {
+		s, _, ok := receivable(c.Seat, c.Kind)
+		switch {
+		case s.Name == "":
+			problems = append(problems, fmt.Sprintf(
+				"%s's contribution %d is to the seat %q, which the mesh does not define", m.Module, i+1, c.Seat))
+		case !ok:
+			problems = append(problems, fmt.Sprintf(
+				"%s's contribution %d to %s is of the kind %q; %s (novox/hq ADR 0212)",
+				m.Module, i+1, s.Name, c.Kind, kindsOf(s)))
+		}
+		if strings.TrimSpace(c.Content) == "" {
+			problems = append(problems, fmt.Sprintf("%s's contribution %d has no content", m.Module, i+1))
+		}
+	}
+	return problems
+}
+
+// seatPlaceholderProblems is what is wrong with one resource's ${contribution:…}: placed only in a
+// file's content, naming a seat and a kind it receives, and only by a module that claims that seat
+// — another would be a second writer of a file there is one of (novox/hq ADR 0212 §3).
+func seatPlaceholderProblems(m Manifest, r map[string]any) []string {
+	var problems []string
+	for _, field := range sortedKeys(r) {
+		v, ok := r[field].(string)
+		if !ok {
+			continue
+		}
+		found := ofContribution.FindAllStringSubmatch(v, -1)
+		if len(found) == 0 {
+			continue
+		}
+		if field != "content" {
+			problems = append(problems, fmt.Sprintf(
+				"%s's resource %v names %s in its %s; contributions are placed only in a file's content",
+				m.Module, r["id"], found[0][0], field))
+			continue
+		}
+		for _, f := range found {
+			seat, kind, two := strings.Cut(f[1], ":")
+			s, _, ok := receivable(seat, kind)
+			if !two || !ok {
+				detail := "the mesh defines no seat " + fmt.Sprintf("%q", seat)
+				if s.Name != "" {
+					detail = s.Name + ": " + kindsOf(s)
+				}
+				problems = append(problems, fmt.Sprintf(
+					"%s's resource %v names %s; a contribution is ${contribution:<seat>:<kind>} (%s)",
+					m.Module, r["id"], f[0], detail))
+				continue
+			}
+			if !m.ClaimsSeat(s.Name) {
+				problems = append(problems, fmt.Sprintf(
+					"%s's resource %v names %s and %s does not claim %s; every module's contributions to a "+
+						"seat are placed by its holder alone (novox/hq ADR 0212)",
+					m.Module, r["id"], f[0], m.Module, s.Name))
+			}
+		}
+	}
+	return problems
+}
+
+// seatContributions is every module's contribution of one kind to one seat (novox/hq ADR 0212 §3):
+// in module order, each module's pieces in the order it declared them, each module's preceded by a
+// comment line naming it in the tool's grammar, and empty when nothing is contributed.
+func seatContributions(modules []Manifest, seat, kind string) string {
+	s, r, ok := receivable(seat, kind)
+	if !ok {
+		return ""
+	}
+	var b strings.Builder
+	for _, m := range inModuleOrder(modules) {
+		named := false
+		for _, c := range m.Contributions {
+			if c.Kind != kind {
+				continue
+			}
+			if cs, known := SeatNamed(c.Seat); !known || cs.Name != s.Name {
+				continue
+			}
+			if !named {
+				fmt.Fprintf(&b, "%s %s\n", r.Comment, m.Module)
+				named = true
+			}
+			b.WriteString(c.Content)
+			if !strings.HasSuffix(c.Content, "\n") {
+				b.WriteString("\n")
+			}
+		}
+	}
+	return b.String()
+}

internal/catalogue/seat_contributions_test.go

@@ -0,0 +1,117 @@
+package catalogue
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+// Defends novox/hq ADR 0212: a seat says what it receives, its holder places it, and a contribution
+// depends on the seat.
+
+func hotkeysHolder() Manifest {
+	return Manifest{Module: "triggerhappy", Claims: []Claim{{Name: HotkeysSeat}}, Resources: []map[string]any{
+		{"id": "triggers", "type": "file", "path": "/etc/triggerhappy/triggers.d/mesh.conf",
+			"content": "# the mesh's triggers\n${contribution:node-hotkeys:trigger}"},
+	}}
+}
+
+func TestAContributionReachesTheHoldersFileInModuleOrderNamedByModule(t *testing.T) {
+	laptop := Manifest{Module: "laptop", Contributions: []SeatContribution{
+		{Seat: HotkeysSeat, Kind: "trigger", Content: "KEY_PROG1 1 play ${machine:account-home}"},
+		{Seat: HotkeysSeat, Kind: "trigger", Content: "KEY_F21 1 touchpad\n"},
+	}}
+	another := Manifest{Module: "another", Contributions: []SeatContribution{
+		{Seat: HotkeysSeat, Kind: "trigger", Content: "KEY_MUTE 1 mute ${shell:zsh:first}"},
+	}}
+	unrelated := Manifest{Module: "bar", Contributions: []SeatContribution{
+		{Seat: DisplaySessionSeat, Kind: "config", Content: "bar { }"},
+	}}
+	r := Resolution{Node: "laptop", Account: "op", Modules: []Manifest{hotkeysHolder(), laptop, another, unrelated}}
+	out, err := r.Declaration(Rendering{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	var file map[string]any
+	for _, res := range out {
+		if res["id"] == "triggerhappy.triggers" {
+			file = res
+		}
+	}
+	if file == nil {
+		t.Fatalf("the holder's file was not composed: %v", out)
+	}
+	// Module order; each module named once; text never read, so neither ${machine:…} nor ${shell:…}
+	// inside a contribution is filled.
+	want := "# the mesh's triggers\n" +
+		"# another\nKEY_MUTE 1 mute ${shell:zsh:first}\n" +
+		"# laptop\nKEY_PROG1 1 play ${machine:account-home}\nKEY_F21 1 touchpad\n"
+	if got := file["content"]; got != want {
+		t.Fatalf("the holder's file is\n%s\nnot\n%s", got, want)
+	}
+}
+
+func TestNoContributionPlacesNothing(t *testing.T) {
+	r := Resolution{Node: "laptop", Account: "op", Modules: []Manifest{hotkeysHolder()}}
+	out, err := r.Declaration(Rendering{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, res := range out {
+		if res["id"] == "triggerhappy.triggers" && res["content"] != "# the mesh's triggers\n" {
+			t.Fatalf("an empty kind left %q", res["content"])
+		}
+	}
+}
+
+func TestAContributionToASeatThatDoesNotReceiveItIsRefused(t *testing.T) {
+	cases := map[string]string{
+		`{"seat":"node-hotkeys","kind":"config","content":"x"}`:          "it receives trigger",
+		`{"seat":"node-nothing","kind":"trigger","content":"x"}`:         "the mesh does not define",
+		`{"seat":"node-hotkeys","kind":"trigger","content":"   "}`:       "has no content",
+		`{"seat":"node-display-session","kind":"trigger","content":"x"}`: "it receives config",
+	}
+	for c, want := range cases {
+		raw := `{"module":"laptop","contributions":[` + c + `]}`
+		if _, err := ParseManifest([]byte(raw)); err == nil || !strings.Contains(err.Error(), want) {
+			t.Errorf("%s: accepted, or refused without %q: %v", c, want, err)
+		}
+	}
+}
+
+func TestAContributionPlaceholderOutsideTheHolderIsRefused(t *testing.T) {
+	raw := `{"module":"laptop","resources":[{"id":"t","type":"file","path":"/etc/t","content":"${contribution:node-hotkeys:trigger}"}]}`
+	if _, err := ParseManifest([]byte(raw)); err == nil || !strings.Contains(err.Error(), "laptop does not claim node-hotkeys") {
+		t.Errorf("a placeholder outside the holder was accepted: %v", err)
+	}
+	raw = `{"module":"triggerhappy","claims":[{"name":"node-hotkeys"}],"resources":[{"id":"t","type":"file","path":"/etc/t","content":"${contribution:node-hotkeys:keys}"}]}`
+	if _, err := ParseManifest([]byte(raw)); err == nil || !strings.Contains(err.Error(), "it receives trigger") {
+		t.Errorf("a placeholder for a kind the seat does not receive was accepted: %v", err)
+	}
+}
+
+func TestAContributionDependsOnItsSeat(t *testing.T) {
+	m := Manifest{Module: "laptop", Contributions: []SeatContribution{
+		{Seat: HotkeysSeat, Kind: "trigger", Content: "x"},
+		{Seat: DisplaySessionSeat, Kind: "config", Content: "y"},
+	}}
+	if got, want := DependsOn(m), []string{DisplaySessionSeat, HotkeysSeat}; !reflect.DeepEqual(got, want) {
+		t.Errorf("depends on %v, want %v", got, want)
+	}
+	catalogue := map[string]Manifest{"laptop": m, "triggerhappy": hotkeysHolder()}
+	if _, err := AssignRefusal(catalogue, "laptop", nil, []string{"laptop"}); err == nil ||
+		!strings.Contains(err.Error(), HotkeysSeat) {
+		t.Errorf("a contributor without the holder was accepted: %v", err)
+	}
+}
+
+func TestTheHotkeysSeatIsTheMeshsAndReceivesTriggers(t *testing.T) {
+	s, ok := SeatNamed(HotkeysSeat)
+	if !ok || s.Scope != ScopeNode || len(s.Receives) != 1 || s.Receives[0].Kind != "trigger" {
+		t.Fatalf("%+v %v", s, ok)
+	}
+	d, _ := SeatNamed(DisplaySessionSeat)
+	if len(d.Receives) != 1 || d.Receives[0].Kind != "config" {
+		t.Fatalf("the display session receives %+v", d.Receives)
+	}
+}

internal/catalogue/seat_dependencies.go

@@ -114,6 +114,13 @@ func contributedTo(m Manifest) []string {
 	for _, c := range m.Shell {
 		out = append(out, placerOf(c.For))
 	}
+	// Any other seat's contribution (novox/hq ADR 0212 §4), by the seat's canonical name; one the
+	// mesh does not define is refused at registration and depends on nothing here.
+	for _, c := range m.Contributions {
+		if s, known := SeatNamed(c.Seat); known {
+			out = append(out, s.Name)
+		}
+	}
 	return out
 }
 

internal/catalogue/seats.go

@@ -40,10 +40,22 @@ type Seat struct {
 	// Serves carries each verb in full — name, description, schema — because a role's tools are the
 	// mesh's to define and an agent's to call (novox/hq ADR 0132, design 33 §2).
 	Serves []Verb
+	// Receives is what other modules may contribute to the seat's holder, by kind (novox/hq ADR
+	// 0212): each kind is text in the tool's own grammar, placed by the holder with
+	// ${contribution:<seat>:<kind>}. Compiled, never stored: like the protocol, it is the mesh's
+	// definition of the role, and the store's rows carry no column for it.
+	Receives []Receivable
 	// Decision is the record that made it a seat.
 	Decision string
 }
 
+// Receivable is one kind of contribution a seat receives (novox/hq ADR 0212 §2): its name, and the
+// comment prefix of the tool's grammar, with which the controller names each contributing module.
+type Receivable struct {
+	Kind    string
+	Comment string
+}
+
 // defaultSeats is the set the mesh ships with — the seed for the control plane's seat table and the
 // fallback when it has none (novox/hq ADR 0122). It is the one place the closed set 0110 defines is
 // written; the store's table is seeded from it and thereafter is the live, editable copy.
@@ -176,6 +188,11 @@ var defaultSeats = append([]Seat{
 	// code modules contribute for the power moments, and publishes the machine's power states as
 	// its events. Every machine has one — every machine boots and shuts down. No verbs yet.
 	{Name: PowerSeat, Scope: ScopeNode, Decision: "novox/hq ADR 0211"},
+	// The machine's hotkeys (novox/hq ADR 0212): the daemon that sees the keys the window manager
+	// does not — a laptop's vendor keys — run by one module per machine, which owns its
+	// configuration. Every other module with keys contributes trigger lines to it.
+	{Name: HotkeysSeat, Scope: ScopeNode, Decision: "novox/hq ADR 0212",
+		Receives: []Receivable{{Kind: "trigger", Comment: "#"}}},
 	// Deferred (novox/hq ADR 0121): renaming to mesh-private-network is a scope + server/client
 	// model change, not a rename, so it stays until that is built.
 	{Name: "the-private-network", Scope: ScopeNode, Decision: "novox/hq ADR 0110"},
@@ -238,6 +255,10 @@ func UseSeats(s []Seat) {
 				row.Accepts, row.Emits, row.Serves = d.Accepts, d.Emits, d.Serves
 			}
 		}
+		// What a seat receives is never stored (novox/hq ADR 0212), so it is always the compiled one.
+		if d, known := byName[row.Name]; known {
+			row.Receives = d.Receives
+		}
 		merged = append(merged, row)
 	}
 	seats = merged

internal/catalogue/seats_test.go

@@ -46,13 +46,13 @@ func TestTheSeatsAreAClosedSetAndEachNamesItsDecision(t *testing.T) {
 			delivered[s.Delivers] = s.Name
 		}
 	}
-	// Thirty-three with node-power (novox/hq ADR 0211); thirty-two since the graphical session's
+	// Thirty-four with node-hotkeys (novox/hq ADR 0212); thirty-three with node-power (ADR 0211); thirty-two since the graphical session's
 	// eleven (ADR 0208); twenty-one with
 	// node-package-manager and node-container-runtime (ADR 0207); nineteen with node-environment and
 	// node-login-shell (ADR 0203, ADR 0204); seventeen with node-build-agent (ADR 0190). One fewer
 	// once the retired mesh-build-machine row goes, when no registered manifest claims it any more.
-	if len(Seats()) != 33 {
-		t.Errorf("the mesh defines %d seats rather than 33; the set is closed, so a change here is "+
+	if len(Seats()) != 34 {
+		t.Errorf("the mesh defines %d seats rather than 34; the set is closed, so a change here is "+
 			"a decision (novox/hq ADR 0110): %s", len(Seats()), seatNames())
 	}
 }