Implement Issue #11: Initial admin account setup on first deploy

When the database has no users, the UI redirects to /setup and prompts
for creation of the first admin account. The setup endpoints are
self-disabling — once any user exists, POST /setup/admin returns 403
and the frontend redirects /setup back to /login. The backend uses an
atomic transaction to prevent race conditions on concurrent requests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/setup/handler.go

@@ -0,0 +1,84 @@
+package setup
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+
+	"git.unsupervised.ca/walkies/internal/auth"
+	"git.unsupervised.ca/walkies/internal/respond"
+)
+
+// TokenIssuer is the subset of auth.Service the setup handler needs.
+type TokenIssuer interface {
+	IssueToken(volunteerID int64, role string) (string, error)
+}
+
+type Handler struct {
+	store   Storer
+	authSvc TokenIssuer
+}
+
+func NewHandler(store *Store, authSvc *auth.Service) *Handler {
+	return &Handler{store: store, authSvc: authSvc}
+}
+
+// NewHandlerFromInterfaces constructs a Handler from interface values, intended for testing.
+func NewHandlerFromInterfaces(store Storer, authSvc TokenIssuer) *Handler {
+	return &Handler{store: store, authSvc: authSvc}
+}
+
+// Status handles GET /api/v1/setup/status.
+func (h *Handler) Status(w http.ResponseWriter, r *http.Request) {
+	needs, err := h.store.NeedsSetup(r.Context())
+	if err != nil {
+		respond.Error(w, http.StatusInternalServerError, "could not check setup status")
+		return
+	}
+	respond.JSON(w, http.StatusOK, map[string]bool{"needs_setup": needs})
+}
+
+// CreateAdmin handles POST /api/v1/setup/admin.
+func (h *Handler) CreateAdmin(w http.ResponseWriter, r *http.Request) {
+	var body struct {
+		Name     string `json:"name"`
+		Email    string `json:"email"`
+		Password string `json:"password"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		respond.Error(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+	if body.Name == "" || body.Email == "" || body.Password == "" {
+		respond.Error(w, http.StatusBadRequest, "name, email, and password are required")
+		return
+	}
+	if len(body.Password) < 8 {
+		respond.Error(w, http.StatusBadRequest, "password must be at least 8 characters")
+		return
+	}
+
+	hashed, err := auth.HashPassword(body.Password)
+	if err != nil {
+		respond.Error(w, http.StatusInternalServerError, "could not hash password")
+		return
+	}
+
+	id, err := h.store.CreateAdmin(r.Context(), body.Name, body.Email, hashed)
+	if errors.Is(err, ErrSetupAlreadyDone) {
+		respond.Error(w, http.StatusForbidden, "setup already completed")
+		return
+	}
+	if err != nil {
+		respond.Error(w, http.StatusInternalServerError, "could not create admin account")
+		return
+	}
+
+	token, err := h.authSvc.IssueToken(id, "admin")
+	if err != nil {
+		respond.Error(w, http.StatusInternalServerError, "could not issue token")
+		return
+	}
+
+	respond.JSON(w, http.StatusCreated, map[string]string{"token": token})
+}

internal/setup/handler_test.go

@@ -0,0 +1,168 @@
+package setup_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"git.unsupervised.ca/walkies/internal/setup"
+)
+
+// ---- fakes ---------------------------------------------------------------
+
+type fakeStore struct {
+	needsSetup     bool
+	needsSetupErr  error
+	createAdminID  int64
+	createAdminErr error
+}
+
+func (f *fakeStore) NeedsSetup(_ context.Context) (bool, error) {
+	return f.needsSetup, f.needsSetupErr
+}
+
+func (f *fakeStore) CreateAdmin(_ context.Context, _, _, _ string) (int64, error) {
+	return f.createAdminID, f.createAdminErr
+}
+
+type fakeTokenIssuer struct {
+	token string
+	err   error
+}
+
+func (f *fakeTokenIssuer) IssueToken(_ int64, _ string) (string, error) {
+	return f.token, f.err
+}
+
+// Compile-time interface checks.
+var _ setup.Storer = (*fakeStore)(nil)
+var _ setup.TokenIssuer = (*fakeTokenIssuer)(nil)
+
+// ---- helpers -------------------------------------------------------------
+
+func do(t *testing.T, handler http.HandlerFunc, method, path, body string) *httptest.ResponseRecorder {
+	t.Helper()
+	var b *bytes.Reader
+	if body != "" {
+		b = bytes.NewReader([]byte(body))
+	} else {
+		b = bytes.NewReader(nil)
+	}
+	req := httptest.NewRequest(method, path, b)
+	if body != "" {
+		req.Header.Set("Content-Type", "application/json")
+	}
+	w := httptest.NewRecorder()
+	handler.ServeHTTP(w, req)
+	return w
+}
+
+// ---- Status tests --------------------------------------------------------
+
+func TestStatus_NeedsSetup(t *testing.T) {
+	h := setup.NewHandlerFromInterfaces(
+		&fakeStore{needsSetup: true},
+		&fakeTokenIssuer{},
+	)
+	w := do(t, h.Status, "GET", "/api/v1/setup/status", "")
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body)
+	}
+	var resp map[string]bool
+	json.NewDecoder(w.Body).Decode(&resp)
+	if !resp["needs_setup"] {
+		t.Error("expected needs_setup=true")
+	}
+}
+
+func TestStatus_SetupDone(t *testing.T) {
+	h := setup.NewHandlerFromInterfaces(
+		&fakeStore{needsSetup: false},
+		&fakeTokenIssuer{},
+	)
+	w := do(t, h.Status, "GET", "/api/v1/setup/status", "")
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body)
+	}
+	var resp map[string]bool
+	json.NewDecoder(w.Body).Decode(&resp)
+	if resp["needs_setup"] {
+		t.Error("expected needs_setup=false")
+	}
+}
+
+// ---- CreateAdmin tests ---------------------------------------------------
+
+func TestCreateAdmin_Success(t *testing.T) {
+	h := setup.NewHandlerFromInterfaces(
+		&fakeStore{createAdminID: 1},
+		&fakeTokenIssuer{token: "jwt-token"},
+	)
+	w := do(t, h.CreateAdmin, "POST", "/api/v1/setup/admin",
+		`{"name":"Admin","email":"admin@example.com","password":"supersecret"}`)
+
+	if w.Code != http.StatusCreated {
+		t.Fatalf("expected 201, got %d: %s", w.Code, w.Body)
+	}
+	var resp map[string]string
+	json.NewDecoder(w.Body).Decode(&resp)
+	if resp["token"] != "jwt-token" {
+		t.Errorf("expected token jwt-token, got %q", resp["token"])
+	}
+}
+
+func TestCreateAdmin_AlreadyDone(t *testing.T) {
+	h := setup.NewHandlerFromInterfaces(
+		&fakeStore{createAdminErr: setup.ErrSetupAlreadyDone},
+		&fakeTokenIssuer{},
+	)
+	w := do(t, h.CreateAdmin, "POST", "/api/v1/setup/admin",
+		`{"name":"Admin","email":"admin@example.com","password":"supersecret"}`)
+
+	if w.Code != http.StatusForbidden {
+		t.Fatalf("expected 403, got %d: %s", w.Code, w.Body)
+	}
+}
+
+func TestCreateAdmin_MissingFields(t *testing.T) {
+	h := setup.NewHandlerFromInterfaces(
+		&fakeStore{},
+		&fakeTokenIssuer{},
+	)
+
+	tests := []struct {
+		name string
+		body string
+	}{
+		{"missing name", `{"email":"a@b.com","password":"supersecret"}`},
+		{"missing email", `{"name":"Admin","password":"supersecret"}`},
+		{"missing password", `{"name":"Admin","email":"a@b.com"}`},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			w := do(t, h.CreateAdmin, "POST", "/api/v1/setup/admin", tc.body)
+			if w.Code != http.StatusBadRequest {
+				t.Fatalf("expected 400, got %d: %s", w.Code, w.Body)
+			}
+		})
+	}
+}
+
+func TestCreateAdmin_PasswordTooShort(t *testing.T) {
+	h := setup.NewHandlerFromInterfaces(
+		&fakeStore{},
+		&fakeTokenIssuer{},
+	)
+	w := do(t, h.CreateAdmin, "POST", "/api/v1/setup/admin",
+		`{"name":"Admin","email":"admin@example.com","password":"short"}`)
+
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("expected 400, got %d: %s", w.Code, w.Body)
+	}
+}

internal/setup/setup.go

@@ -0,0 +1,68 @@
+package setup
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+)
+
+var ErrSetupAlreadyDone = errors.New("setup already completed")
+
+// Storer is the interface for setup-related DB operations.
+type Storer interface {
+	NeedsSetup(ctx context.Context) (bool, error)
+	CreateAdmin(ctx context.Context, name, email, hashedPassword string) (int64, error)
+}
+
+type Store struct {
+	db *sql.DB
+}
+
+func NewStore(db *sql.DB) *Store {
+	return &Store{db: db}
+}
+
+// NeedsSetup returns true when the volunteers table has zero rows.
+func (s *Store) NeedsSetup(ctx context.Context) (bool, error) {
+	var count int
+	err := s.db.QueryRowContext(ctx, `SELECT COUNT(*) FROM volunteers`).Scan(&count)
+	if err != nil {
+		return false, err
+	}
+	return count == 0, nil
+}
+
+// CreateAdmin atomically checks that no users exist and inserts the first admin.
+func (s *Store) CreateAdmin(ctx context.Context, name, email, hashedPassword string) (int64, error) {
+	tx, err := s.db.BeginTx(ctx, nil)
+	if err != nil {
+		return 0, err
+	}
+	defer tx.Rollback()
+
+	var count int
+	if err := tx.QueryRowContext(ctx, `SELECT COUNT(*) FROM volunteers`).Scan(&count); err != nil {
+		return 0, err
+	}
+	if count > 0 {
+		return 0, ErrSetupAlreadyDone
+	}
+
+	res, err := tx.ExecContext(ctx,
+		`INSERT INTO volunteers (name, email, password, role, active, operational_roles) VALUES (?, ?, ?, 'admin', 1, '')`,
+		name, email, hashedPassword,
+	)
+	if err != nil {
+		return 0, err
+	}
+
+	id, err := res.LastInsertId()
+	if err != nil {
+		return 0, err
+	}
+
+	if err := tx.Commit(); err != nil {
+		return 0, err
+	}
+	return id, nil
+}