slice 8C Phase B.1: agentapi disk client (Disks/AssignDisk/EjectDisk/FormatDisk)

ErrFormatRefused surfaces the agent's data-bearing refusal distinctly. Tests:
list, blank format OK, data-bearing refused, eject dependents.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

controller/internal/agentapi/disks_test.go

@@ -0,0 +1,92 @@
+package agentapi
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func diskStub(t *testing.T) (*httptest.Server, string) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /disks", func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`{"ok":true,"data":{"vmid":8200,"disks":[{"name":"bulk","data_bearing":true,"data_reason":"has ext4"}]}}`))
+	})
+	mux.HandleFunc("POST /disks/assign", func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`{"ok":true,"data":{"assigned":"/mnt/data"}}`))
+	})
+	mux.HandleFunc("POST /disks/eject", func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write([]byte(`{"ok":true,"data":{"ejected":"/mnt/bulk","dependent_guests":[8200]}}`))
+	})
+	mux.HandleFunc("POST /disks/format", func(w http.ResponseWriter, r *http.Request) {
+		var body struct{ Device, FSType string }
+		_ = decodeJSON(r, &body)
+		if strings.Contains(body.Device, "data") {
+			w.WriteHeader(http.StatusForbidden)
+			_, _ = w.Write([]byte(`{"ok":false,"error":"device is data-bearing — operator authorization (pending_signature)"}`))
+			return
+		}
+		_, _ = w.Write([]byte(`{"ok":true,"data":{"device":"` + body.Device + `","formatted":true}}`))
+	})
+	s := httptest.NewTLSServer(mux)
+	return s, strings.TrimPrefix(s.URL, "https://")
+}
+
+func decodeJSON(r *http.Request, v any) error {
+	return json.NewDecoder(r.Body).Decode(v)
+}
+
+func clientFor(t *testing.T, s *httptest.Server, endpoint string) *Client {
+	pin := leafPin(t, s)
+	c, err := New(endpoint, "TOK", pin)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return c
+}
+
+func TestDisks_List(t *testing.T) {
+	s, ep := diskStub(t)
+	defer s.Close()
+	c := clientFor(t, s, ep)
+	resp, err := c.Disks(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(resp.Disks) != 1 || !resp.Disks[0].DataBearing {
+		t.Fatalf("unexpected: %+v", resp)
+	}
+}
+
+func TestFormat_BlankOK(t *testing.T) {
+	s, ep := diskStub(t)
+	defer s.Close()
+	c := clientFor(t, s, ep)
+	res, err := c.FormatDisk(context.Background(), "/dev/sdb", "ext4")
+	if err != nil || !res.Formatted {
+		t.Fatalf("blank format: %v %+v", err, res)
+	}
+}
+
+func TestFormat_DataBearingRefused(t *testing.T) {
+	s, ep := diskStub(t)
+	defer s.Close()
+	c := clientFor(t, s, ep)
+	_, err := c.FormatDisk(context.Background(), "/dev/data-disk", "ext4")
+	if !errors.Is(err, ErrFormatRefused) {
+		t.Fatalf("expected ErrFormatRefused, got %v", err)
+	}
+}
+
+func TestEject_Dependents(t *testing.T) {
+	s, ep := diskStub(t)
+	defer s.Close()
+	c := clientFor(t, s, ep)
+	res, err := c.EjectDisk(context.Background(), "/mnt/bulk")
+	if err != nil || len(res.DependentGuests) != 1 || res.DependentGuests[0] != 8200 {
+		t.Fatalf("eject: %v %+v", err, res)
+	}
+}