Let a bundle pull one message from its listed worker and settle it, so a build module takes an ask only when it has a free slot, in its workers' order (issue 1887 A11, ADR 0525 §4)

node-tools/internal/runtime/runtime.go

@@ -14,6 +14,7 @@ import (
 	"sort"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/novox/mesh-tools/node-tools/internal/announce"
 	"github.com/novox/mesh-tools/node-tools/internal/bus"
@@ -759,6 +760,9 @@ type seatAsked struct {
 	Worker  string          `json:"worker"`
 	Bucket  string          `json:"bucket"`
 	Key     string          `json:"key"`
+	// WaitMS is how long a pull waits for a message (none when 0); Fate what a settle gives one (issue 1887 A11).
+	WaitMS int    `json:"wait_ms"`
+	Fate   string `json:"fate"`
 }
 
 // Seat answers a bundle's seat traffic, each as the module and only as far as its membership lists:
@@ -792,6 +796,19 @@ func (b *moduleBus) Seat(verb string, params json.RawMessage, handOn func(string
 			return json.RawMessage("null"), err
 		}
 		return json.Marshal(entry)
+	case "pull":
+		// One message from a worker the membership lists, never a prefetch: a build module pulls an ask only when it
+		// has room, from its workers in their order (novox/hq ADR 0525 §4; issue 1887 A11).
+		p, err := conn.SeatPull(b.module, asked.Worker, time.Duration(asked.WaitMS)*time.Millisecond)
+		if err != nil || p == nil {
+			return json.RawMessage("null"), err
+		}
+		return json.Marshal(p)
+	case "settle":
+		if err := conn.SeatSettle(b.module, asked.ID, asked.Fate); err != nil {
+			return nil, err
+		}
+		return json.RawMessage(`{}`), nil
 	case "take":
 		key := "take " + asked.Worker
 		if b.bound(key) {