diff --git a/boss_test.go b/boss_test.go
index 0330e5c..7f991e7 100644
--- a/boss_test.go
+++ b/boss_test.go
@@ -3,9 +3,11 @@ package main
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"path/filepath"
+	"slices"
 	"strings"
 	"sync"
 	"testing"
@@ -333,3 +335,172 @@ func TestCrowsRegistryEmptyWithoutStore(t *testing.T) {
 		t.Fatalf("want no crows, got %v", out.Crows)
 	}
 }
+
+// --- #43: Boss creates nests and assigns members ---
+
+// listNests returns every nest from GET /api/nests.
+func listNests(t *testing.T, ts *httptest.Server) []map[string]any {
+	t.Helper()
+	resp, err := http.Get(ts.URL + "/api/nests")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("GET /api/nests: want 200, got %d", resp.StatusCode)
+	}
+	var out struct {
+		Nests []map[string]any `json:"nests"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
+		t.Fatal(err)
+	}
+	return out.Nests
+}
+
+func findNest(t *testing.T, ts *httptest.Server, name string) map[string]any {
+	t.Helper()
+	for _, n := range listNests(t, ts) {
+		if n["name"] == name {
+			return n
+		}
+	}
+	return nil
+}
+
+func nestCrowNames(nest map[string]any) []string {
+	raw, _ := nest["crows"].([]any)
+	out := make([]string, 0, len(raw))
+	for _, c := range raw {
+		out = append(out, c.(string))
+	}
+	slices.Sort(out)
+	return out
+}
+
+func TestBossCreatesNest(t *testing.T) {
+	s, bb := newBossServer(t,
+		`SPIN {"name":"Ash","persona":"Soot","trust":"stranger"}`,
+		`NEST {"name":"Launch","crows":["Hugin","Ash"]}`,
+	)
+	ts := serve(s)
+	defer ts.Close()
+	labID := newNest(t, ts, "Lab", `"Hugin"`)
+
+	// Ash must exist as a registry crow: spin it through Boss first.
+	askBoss(t, ts, labID, "spin up a crow named Ash")
+	bossSay(t, ts, labID, 2)
+
+	askBoss(t, ts, labID, "make a nest Launch with Hugin and Ash")
+
+	var launch map[string]any
+	deadline := time.Now().Add(2 * time.Second)
+	for launch == nil && time.Now().Before(deadline) {
+		launch = findNest(t, ts, "Launch")
+		if launch == nil {
+			time.Sleep(20 * time.Millisecond)
+		}
+	}
+	if launch == nil {
+		t.Fatalf("Boss must create the nest Launch, nests: %v", listNests(t, ts))
+	}
+	if got := nestCrowNames(launch); !slices.Equal(got, []string{"Ash", "Hugin"}) {
+		t.Fatalf("Launch crows must be exactly [Ash Hugin], got %v", got)
+	}
+
+	// Boss announces membership in the NEW nest: a say to the owner.
+	announced := false
+	for _, m := range awaitMessages(t, ts, launch["nest_id"].(string), 1) {
+		if m["author"] == "Boss" && m["kind"] == "say" && m["to"] == "owner" {
+			announced = true
+		}
+	}
+	if !announced {
+		t.Fatalf("Boss must post a say to the owner in Launch, got %v",
+			nestMessages(t, ts, launch["nest_id"].(string)))
+	}
+
+	// And confirms in the requesting nest.
+	confirmed := false
+	for _, m := range awaitMessages(t, ts, labID, 4) {
+		if m["author"] == "Boss" && m["kind"] == "say" && strings.Contains(m["text"].(string), "Launch") {
+			confirmed = true
+		}
+	}
+	if !confirmed {
+		t.Fatalf("Boss must confirm the new nest in Lab, got %v", nestMessages(t, ts, labID))
+	}
+	if bb.count() != 2 {
+		t.Fatalf("two orders are two model calls, got %d", bb.count())
+	}
+}
+
+func TestBossNestUnknownMemberRefused(t *testing.T) {
+	s, _ := newBossServer(t, `NEST {"name":"Nope","crows":["Gandalf"]}`)
+	ts := serve(s)
+	defer ts.Close()
+	labID := newNest(t, ts, "Lab", `"Hugin"`)
+
+	before := len(listNests(t, ts))
+	askBoss(t, ts, labID, "make a nest Nope with Gandalf")
+
+	say := bossSay(t, ts, labID, 2)
+	text, _ := say["text"].(string)
+	if strings.HasPrefix(text, "NEST") {
+		t.Fatalf("Boss must interpret the order, not echo it back: %q", text)
+	}
+	if !strings.Contains(text, "Gandalf") {
+		t.Fatalf("the refusal must name the unknown member, got %q", text)
+	}
+	if after := len(listNests(t, ts)); after != before {
+		t.Fatalf("an unknown member must refuse the whole create: %d before, %d after", before, after)
+	}
+}
+
+func TestBossNestCapRespected(t *testing.T) {
+	s, _ := newBossServer(t, `NEST {"name":"Overflow","crows":["Hugin"]}`)
+	ts := serve(s)
+	defer ts.Close()
+	labID := newNest(t, ts, "Lab", `"Hugin"`)
+
+	// Fill the store to its cap: todo + Lab + (maxNests-2) pads.
+	for i := 0; 2+i < maxNests; i++ {
+		if _, err := s.nests.Create(fmt.Sprintf("Pad %d", i), []string{"Hugin"}); err != nil {
+			t.Fatalf("padding nests: %v", err)
+		}
+	}
+	if n := len(listNests(t, ts)); n != maxNests {
+		t.Fatalf("test setup: want %d nests, got %d", maxNests, n)
+	}
+
+	askBoss(t, ts, labID, "make a nest Overflow with Hugin") // 201: no 500 at the front door
+	say := bossSay(t, ts, labID, 2)
+	text, _ := say["text"].(string)
+	if !strings.Contains(text, fmt.Sprintf("at most %d nests", maxNests)) {
+		t.Fatalf("Boss must report the store's cap refusal, got %q", text)
+	}
+	if findNest(t, ts, "Overflow") != nil {
+		t.Fatal("a capped create must not make a nest")
+	}
+}
+
+func TestBossNestGoesThroughFlock(t *testing.T) {
+	s, _ := newBossServer(t, `NEST {"name":"Launch","crows":["Hugin","Munin"]}`)
+	s.p.Flock.sem = make(chan struct{}, 0) // saturated flock: ask must wait, never act
+	ts := serve(s)
+	defer ts.Close()
+	labID := newNest(t, ts, "Lab", `"Hugin"`)
+
+	before := len(listNests(t, ts))
+	askBoss(t, ts, labID, "make a nest Launch with Hugin and Munin")
+	time.Sleep(300 * time.Millisecond)
+
+	if n := len(listNests(t, ts)); n != before {
+		t.Fatalf("a saturated flock must not create a nest, got %v", listNests(t, ts))
+	}
+	for _, m := range nestMessages(t, ts, labID) {
+		if m["author"] == "Boss" {
+			t.Fatalf("a saturated flock must not produce a Boss message, got %v", m)
+		}
+	}
+}