feat(sca): add customer-set spend limit (#55)

api/handlers/account.go

@@ -0,0 +1,111 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"terminalShop/api/middleware"
+	"terminalShop/pkg/audit"
+	"terminalShop/pkg/database"
+	"terminalShop/pkg/models"
+	"terminalShop/pkg/utils"
+)
+
+// AccountHandler serves JWT-authed, customer-facing account-settings endpoints.
+// Unlike AdminUserHandler (X-Admin-Key gated), every route here edits the
+// logged-in user's own row, identified by the JWT user id in context.
+type AccountHandler struct {
+	// maxOrderCents is the global spend cap, needed to bound a self-limit: a
+	// customer may only TIGHTEN their effective ceiling, never raise it.
+	maxOrderCents int
+}
+
+// NewAccountHandler constructs an AccountHandler. maxOrderCents is the global
+// MAX_ORDER_CENTS, wired from cfg in routes.SetupRoutes (same value the cart
+// handler receives).
+func NewAccountHandler(maxOrderCents int) *AccountHandler {
+	return &AccountHandler{maxOrderCents: maxOrderCents}
+}
+
+// SetSpendLimit sets or clears the logged-in user's self-service spend limit
+// (User.SelfLimitCents). Body: {"self_limit_cents": <int|null>}.
+//   - null -> clears the self-limit; the user reverts to the admin/global cap
+//   - 0    -> a real "block everything" ceiling (NOT an off-switch; that is the
+//     whole point of a customer-set limit — it can only tighten)
+//   - >0   -> custom ceiling, must be <= the effective admin/global cap
+//
+// Security: this endpoint is JWT-authed and edits the caller's OWN row, so a
+// self-limit is LOWER-ONLY. A value above the user's effective admin/global cap
+// is rejected here (HTTP 400) so a compromised session cannot lift its own
+// ceiling; the min() fold in cart.go:ConvertCart is the authoritative second
+// guard. Negative values are rejected at the write boundary (the ConvertCart
+// read path also ignores a stray negative from a direct DB write).
+//
+// Mirrors AdminUserHandler.SetUserOrderCap but reads the user id from the JWT
+// context instead of a {id} URL param, uses a distinct body key + audit event,
+// and gates the value against the cap.
+func (h *AccountHandler) SetSpendLimit(w http.ResponseWriter, r *http.Request) {
+	db := database.GetDB().WithContext(r.Context())
+	userID := middleware.UserIDFromContext(r.Context())
+
+	var raw map[string]json.RawMessage
+	if err := json.NewDecoder(r.Body).Decode(&raw); err != nil {
+		utils.RespondError(w, http.StatusBadRequest, "INVALID_BODY", "invalid request body", nil)
+		return
+	}
+	rawLimit, ok := raw["self_limit_cents"]
+	if !ok {
+		utils.RespondError(w, http.StatusBadRequest, "MISSING_FIELD", "self_limit_cents is required (use null to clear the limit)", nil)
+		return
+	}
+
+	var limitCents *int
+	if string(rawLimit) != "null" {
+		var n int
+		if err := json.Unmarshal(rawLimit, &n); err != nil {
+			utils.RespondError(w, http.StatusBadRequest, "INVALID_BODY", "self_limit_cents must be an integer or null", nil)
+			return
+		}
+		if n < 0 {
+			utils.RespondError(w, http.StatusBadRequest, "INVALID_LIMIT", "self_limit_cents must be >= 0 (use null to clear the limit)", nil)
+			return
+		}
+		limitCents = &n
+	}
+
+	var user models.User
+	if err := db.First(&user, userID).Error; err != nil {
+		utils.RespondError(w, http.StatusNotFound, "USER_NOT_FOUND", "user not found", nil)
+		return
+	}
+
+	// A self-limit may only tighten the effective cap, never raise it. Compute
+	// the user's effective admin/global ceiling exactly as cart.go:ConvertCart
+	// does (per-user override wins when present and non-negative; an active cap
+	// is > 0). Reject any self-limit above an ACTIVE admin ceiling. When no admin
+	// ceiling is active (global disabled and no override) there is nothing to
+	// raise, so any non-negative self-limit is allowed — it can only ADD a cap.
+	if limitCents != nil {
+		adminCap := h.maxOrderCents
+		if user.MaxOrderCents != nil && *user.MaxOrderCents >= 0 {
+			adminCap = *user.MaxOrderCents
+		}
+		if adminCap > 0 && *limitCents > adminCap {
+			utils.RespondError(w, http.StatusBadRequest, "SELF_LIMIT_ABOVE_CAP", "self_limit_cents may not exceed your account spend cap", map[string]any{"self_limit_cents": *limitCents, "cap_cents": adminCap})
+			return
+		}
+	}
+
+	// Map form so a nil pointer persists SQL NULL; a struct Updates would skip it.
+	if err := db.Model(&user).Updates(map[string]any{"self_limit_cents": limitCents}).Error; err != nil {
+		utils.RespondError(w, http.StatusInternalServerError, "DATABASE_ERROR", "failed to update spend limit", nil)
+		return
+	}
+
+	audit.UserSelfLimitSet(user.ID, limitCents)
+
+	utils.RespondSuccess(w, http.StatusOK, map[string]any{
+		"user_id":          user.ID,
+		"self_limit_cents": limitCents,
+	})
+}

api/handlers/account_test.go

@@ -0,0 +1,118 @@
+package handlers
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+
+	"terminalShop/api/middleware"
+	"terminalShop/pkg/database"
+	"terminalShop/pkg/models"
+)
+
+func TestSetSpendLimit(t *testing.T) {
+	const globalCap = 5000
+	cases := []struct {
+		name       string
+		seedSelf   *int // starting SelfLimitCents on the row
+		seedAdmin  *int // per-user MaxOrderCents override (effective admin cap)
+		body       string
+		wantStatus int
+		wantCode   string // error code; "" means success
+		wantLimit  *int   // expected SelfLimitCents after a successful update
+	}{
+		{"set positive under cap", nil, nil, `{"self_limit_cents":2000}`, http.StatusOK, "", intPtr(2000)},
+		{"set zero blocks all", nil, nil, `{"self_limit_cents":0}`, http.StatusOK, "", intPtr(0)},
+		{"set equal to cap", nil, nil, `{"self_limit_cents":5000}`, http.StatusOK, "", intPtr(5000)},
+		{"clear with null", intPtr(2000), nil, `{"self_limit_cents":null}`, http.StatusOK, "", nil},
+		{"overwrite existing", intPtr(2000), nil, `{"self_limit_cents":1000}`, http.StatusOK, "", intPtr(1000)},
+		{"above global cap rejected", nil, nil, `{"self_limit_cents":6000}`, http.StatusBadRequest, "SELF_LIMIT_ABOVE_CAP", nil},
+		{"under per-user override accepted", nil, intPtr(10000), `{"self_limit_cents":8000}`, http.StatusOK, "", intPtr(8000)},
+		{"above per-user override rejected", nil, intPtr(10000), `{"self_limit_cents":12000}`, http.StatusBadRequest, "SELF_LIMIT_ABOVE_CAP", nil},
+		{"negative rejected", nil, nil, `{"self_limit_cents":-1}`, http.StatusBadRequest, "INVALID_LIMIT", nil},
+		{"missing field rejected", nil, nil, `{}`, http.StatusBadRequest, "MISSING_FIELD", nil},
+		{"non-integer rejected", nil, nil, `{"self_limit_cents":"lots"}`, http.StatusBadRequest, "INVALID_BODY", nil},
+		{"malformed json rejected", nil, nil, `{`, http.StatusBadRequest, "INVALID_BODY", nil},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			user := setupOrderTestDB(t)
+			db := database.GetDB()
+			if tc.seedSelf != nil {
+				if err := db.Model(&user).Update("self_limit_cents", *tc.seedSelf).Error; err != nil {
+					t.Fatalf("seed self limit: %v", err)
+				}
+			}
+			if tc.seedAdmin != nil {
+				if err := db.Model(&user).Update("max_order_cents", *tc.seedAdmin).Error; err != nil {
+					t.Fatalf("seed admin cap: %v", err)
+				}
+			}
+
+			handler := NewAccountHandler(globalCap)
+			req := authRequest("PUT", "/api/v1/account/spend-limit", []byte(tc.body), user.ID)
+			w := httptest.NewRecorder()
+			handler.SetSpendLimit(w, req)
+
+			if w.Code != tc.wantStatus {
+				t.Fatalf("status: want %d got %d (%s)", tc.wantStatus, w.Code, w.Body.String())
+			}
+			assertErrCode(t, w, tc.wantCode)
+
+			var got models.User
+			if err := db.First(&got, user.ID).Error; err != nil {
+				t.Fatalf("reload user: %v", err)
+			}
+			if tc.wantStatus == http.StatusOK {
+				if !eqIntPtr(got.SelfLimitCents, tc.wantLimit) {
+					t.Errorf("db SelfLimitCents: want %s got %s", fmtIntPtr(tc.wantLimit), fmtIntPtr(got.SelfLimitCents))
+				}
+			} else if !eqIntPtr(got.SelfLimitCents, tc.seedSelf) {
+				// A rejected request must not mutate the column.
+				t.Errorf("rejected request changed db limit: want %s got %s", fmtIntPtr(tc.seedSelf), fmtIntPtr(got.SelfLimitCents))
+			}
+		})
+	}
+}
+
+// TestSetSpendLimit_CapDisabledAllowsAnyLimit: with no active admin ceiling
+// (global 0, no override) any non-negative self-limit is accepted — a self-limit
+// can only ADD a ceiling, so there is nothing to raise.
+func TestSetSpendLimit_CapDisabledAllowsAnyLimit(t *testing.T) {
+	user := setupOrderTestDB(t)
+	handler := NewAccountHandler(0) // global cap disabled
+	req := authRequest("PUT", "/api/v1/account/spend-limit", []byte(`{"self_limit_cents":999999}`), user.ID)
+	w := httptest.NewRecorder()
+	handler.SetSpendLimit(w, req)
+	if w.Code != http.StatusOK {
+		t.Fatalf("status: want 200 got %d (%s)", w.Code, w.Body.String())
+	}
+	var got models.User
+	if err := database.GetDB().First(&got, user.ID).Error; err != nil {
+		t.Fatalf("reload user: %v", err)
+	}
+	if !eqIntPtr(got.SelfLimitCents, intPtr(999999)) {
+		t.Errorf("db SelfLimitCents: want 999999 got %s", fmtIntPtr(got.SelfLimitCents))
+	}
+}
+
+// TestSetSpendLimit_RequireAuthGate exercises the JWT gate through a real
+// router: no user context => 401, the handler is never reached.
+func TestSetSpendLimit_RequireAuthGate(t *testing.T) {
+	setupOrderTestDB(t)
+	router := chi.NewRouter()
+	router.With(middleware.RequireAuth).
+		Put("/api/v1/account/spend-limit", NewAccountHandler(5000).SetSpendLimit)
+
+	req := httptest.NewRequest("PUT", "/api/v1/account/spend-limit", strings.NewReader(`{"self_limit_cents":1000}`))
+	w := httptest.NewRecorder()
+	router.ServeHTTP(w, req)
+	if w.Code != http.StatusUnauthorized {
+		t.Fatalf("status: want 401 got %d", w.Code)
+	}
+	assertErrCode(t, w, "UNAUTHORIZED")
+}

api/routes/routes.go

@@ -54,6 +54,7 @@ func SetupRoutes(
 	webhookHandler := handlers.NewWebhookHandler(stripeWebhookSecret, shippoWebhookSecret)
 	slackHandler := handlers.NewSlackHandler(slackSigningSecret, adminAPIKey, apiPort, shippoWebhookSecret)
 	adminUserHandler := handlers.NewAdminUserHandler()
+	accountHandler := handlers.NewAccountHandler(maxOrderCents)
 
 	// Short payment redirect and success page — no auth required.
 	r.Get("/pay/{token}", handlers.PayRedirect)
@@ -105,6 +106,11 @@ func SetupRoutes(
 
 			r.Get("/view/init", viewHandler.GetViewInit)
 
+			// Account self-service settings, JWT-authed, edits the callers
+			// own row (user id from context, never a URL param). Distinct from
+			// the admin /users/{id}/order-cap setter in the RequireAdmin group.
+			r.Put("/account/spend-limit", accountHandler.SetSpendLimit)
+
 			// Cart
 			r.Route("/cart", func(r chi.Router) {
 				r.Get("/", cartHandler.GetCart)

pkg/api/client.go

@@ -453,6 +453,44 @@ func (c *Client) SetCartCard(cardID uint) error {
 	return nil
 }
 
+func (c *Client) SetSpendLimit(cents *int) error {
+	url := fmt.Sprintf("%s/api/v1/account/spend-limit", c.BaseURL)
+
+	body := map[string]any{
+		"self_limit_cents": cents,
+	}
+	jsonData, err := json.Marshal(body)
+	if err != nil {
+		return fmt.Errorf("failed to marshal request: %w", err)
+	}
+
+	req, err := http.NewRequest("PUT", url, bytes.NewBuffer(jsonData))
+	if err != nil {
+		return fmt.Errorf("failed to create request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := c.doRequest(req)
+	if err != nil {
+		return fmt.Errorf("failed to set spend limit: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	var result APIResponse
+	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
+		return fmt.Errorf("failed to decode response: %w", err)
+	}
+
+	if !result.Success {
+		if result.Error != nil {
+			return fmt.Errorf("%s: %s", result.Error.Code, result.Error.Message)
+		}
+		return fmt.Errorf("failed to set spend limit")
+	}
+
+	return nil
+}
+
 // ClearCart removes all items from the user's cart.
 func (c *Client) ClearCart() error {
 	url := fmt.Sprintf("%s/api/v1/cart", c.BaseURL)

pkg/audit/audit.go

@@ -51,6 +51,7 @@ const (
 	eventOrderDelivered         eventType = "order_delivered"
 	eventTrackingMarkedManually eventType = "tracking_marked_manually"
 	eventUserOrderCapSet        eventType = "user_order_cap_set"
+	eventUserSelfLimitSet       eventType = "user_self_limit_set"
 )
 
 type event struct {
@@ -401,3 +402,26 @@ func UserOrderCapSet(actor string, userID uint, capCents *int) {
 	}
 	slog.Info("audit", e.attrs()...)
 }
+
+// UserSelfLimitSet records a customer changing their own self-service spend
+// limit (User.SelfLimitCents) via the JWT-authed account endpoint. Kept
+// deliberately distinct from UserOrderCapSet (the operator's admin-gated
+// override) so the customer action and the operator action are never conflated
+// in the audit trail. A nil capCents means the self-limit was cleared (the user
+// reverts to the admin/global cap). Unlike the admin cap, an explicit 0 here is
+// a real "block everything" ceiling, not an off-switch, so Status distinguishes
+// "set" from "cleared" and a cap of 0 (which attrs() omits) stays legible.
+func UserSelfLimitSet(userID uint, capCents *int) {
+	e := event{
+		Event:  eventUserSelfLimitSet,
+		Actor:  "self",
+		UserID: userID,
+	}
+	if capCents == nil {
+		e.Status = "cleared"
+	} else {
+		e.Status = "set"
+		e.CapCents = *capCents
+	}
+	slog.Info("audit", e.attrs()...)
+}

pkg/models/coffee.go

@@ -33,6 +33,7 @@ var AccountMenuItems = []string{
 	"order history",
 	"addresses",
 	"cards",
+	"spend limit",
 	"faq",
 	"about",
 }

pkg/models/user.go

@@ -41,6 +41,7 @@ type PublicUser struct {
 	SSHKeyFingerprint string    `json:"ssh_key_fingerprint"`
 	Name              string    `json:"name,omitempty"`
 	Email             string    `json:"email,omitempty"`
+	SelfLimitCents    *int      `json:"self_limit_cents,omitempty"`
 	CreatedAt         time.Time `json:"created_at"`
 }
 
@@ -51,6 +52,7 @@ func (u *User) ToPublic() PublicUser {
 		SSHKeyFingerprint: u.SSHKeyFingerprint,
 		Name:              u.Name,
 		Email:             u.Email,
+		SelfLimitCents:    u.SelfLimitCents,
 		CreatedAt:         u.CreatedAt,
 	}
 }

pkg/tui/account.go

@@ -1,8 +1,11 @@
 package tui
 
 import (
+	"fmt"
+	"strconv"
 	"strings"
 
+	"charm.land/bubbles/v2/textinput"
 	"charm.land/bubbles/v2/viewport"
 	tea "charm.land/bubbletea/v2"
 	"charm.land/lipgloss/v2"
@@ -82,6 +85,8 @@ func (m Model) getAccountDetailContent() string {
 		return m.AddressesView(detailContentWidth)
 	case "cards":
 		return m.CardsView(detailContentWidth)
+	case "spend limit":
+		return m.SpendLimitView(detailContentWidth)
 	case "faq":
 		questionStyle := m.theme.TextHighlight().Bold(true)
 		contentStyle := m.theme.TextBody().Width(detailContentWidth)
@@ -170,7 +175,7 @@ func (m Model) BuildAccountView() string {
 	// the menu, and falls back to the gray pill when focus has moved into the
 	// detail area (browsing orders, managing addresses/cards, scrolling faq).
 	focusedInside := m.account.orderViewState > 0 || m.account.addressListFocused ||
-		m.account.cardListFocused || m.account.faqFocused
+		m.account.cardListFocused || m.account.faqFocused || m.account.spendLimitFocused
 	pillBg := m.theme.Highlight()
 	if focusedInside {
 		pillBg = cPill
@@ -257,6 +262,25 @@ func (m Model) AboutView(width int) string {
 }
 
 func (m Model) AccountUpdate(msg tea.Msg) (Model, tea.Cmd) {
+	// Async result of a spend-limit save (delivered here because the account
+	// page is active when the command resolves).
+	if saved, ok := msg.(spendLimitSavedMsg); ok {
+		m.account.spendLimitSaving = false
+		if saved.Err != nil {
+			m.account.spendLimitErr = friendlySpendLimitError(saved.Err)
+			return m, nil
+		}
+		if m.User != nil {
+			m.User.SelfLimitCents = saved.Cents
+		}
+		m.account.spendLimitFocused = false
+		m.account.spendLimitInput.Blur()
+		m.account.spendLimitErr = ""
+		m.footer = defaultAccountFooter()
+		m.notice = &VisibleNotice{message: "Spend limit updated"}
+		return m, nil
+	}
+
 	keyMsg, ok := msg.(tea.KeyMsg)
 	if !ok {
 		// Pass non-key messages to viewport (e.g. window resize)
@@ -265,6 +289,24 @@ func (m Model) AccountUpdate(msg tea.Msg) (Model, tea.Cmd) {
 		return m, cmd
 	}
 
+	// While the spend-limit input is focused it owns the keyboard: enter saves,
+	// esc cancels, everything else edits the field.
+	if m.account.spendLimitFocused {
+		switch keyMsg.String() {
+		case "esc":
+			m.account.spendLimitFocused = false
+			m.account.spendLimitInput.Blur()
+			m.account.spendLimitErr = ""
+			m.footer = defaultAccountFooter()
+			return m, nil
+		case "enter":
+			return m.submitSpendLimit()
+		}
+		var cmd tea.Cmd
+		m.account.spendLimitInput, cmd = m.account.spendLimitInput.Update(msg)
+		return m, cmd
+	}
+
 	selectedItem := ""
 	if m.account.cursor < len(models.AccountMenuItems) {
 		selectedItem = models.AccountMenuItems[m.account.cursor]
@@ -423,6 +465,26 @@ func (m Model) AccountUpdate(msg tea.Msg) (Model, tea.Cmd) {
 					{key: "esc", value: "back"},
 				}
 			}
+		case "spend limit":
+			if !m.account.spendLimitFocused {
+				ti := textinput.New()
+				ti.Prompt = ""
+				ti.Placeholder = "cents (blank = no limit)"
+				ti.CharLimit = 9
+				// Prefill with the current limit so the user edits rather than retypes.
+				if m.User != nil && m.User.SelfLimitCents != nil {
+					ti.SetValue(strconv.Itoa(*m.User.SelfLimitCents))
+				}
+				cmd := ti.Focus()
+				m.account.spendLimitInput = ti
+				m.account.spendLimitFocused = true
+				m.account.spendLimitErr = ""
+				m.footer = []footerCommand{
+					{key: "enter", value: "save"},
+					{key: "esc", value: "cancel"},
+				}
+				return m, cmd
+			}
 		case "faq":
 			if !m.account.faqFocused {
 				m.account.faqFocused = true
@@ -438,14 +500,7 @@ func (m Model) AccountUpdate(msg tea.Msg) (Model, tea.Cmd) {
 		}
 
 	case "esc":
-		accountDefaultFooter := []footerCommand{
-			{key: "j/k", value: "navigate"},
-			{key: "enter", value: "select"},
-			{key: "s", value: "shop"},
-			{key: "c", value: "cart"},
-			{key: "?", value: "help"},
-			{key: "q", value: "quit"},
-		}
+		accountDefaultFooter := defaultAccountFooter()
 		if m.account.addressDeleting != nil {
 			m.account.addressDeleting = nil
 		} else if m.account.addressListFocused {
@@ -485,3 +540,123 @@ func (m Model) AccountUpdate(msg tea.Msg) (Model, tea.Cmd) {
 	}
 	return m, nil
 }
+
+// spendLimitSavedMsg carries the result of an async SetSpendLimit call back to
+// AccountUpdate. Cents is the value that was sent (echoed so the view can update
+// without a refetch); Err is non-nil when the save failed.
+type spendLimitSavedMsg struct {
+	Cents *int
+	Err   error
+}
+
+// SpendLimitView renders the self-service spend-limit panel: the current limit,
+// and — when focused — the editable input. Layout follows the label/box idiom
+// used by the refund composer (pkg/tui/refund.go).
+func (m Model) SpendLimitView(width int) string {
+	labelStyle := m.theme.TextLabel()
+	bodyStyle := m.theme.TextBody().Width(width)
+	hintStyle := m.theme.TextDim()
+
+	current := "no limit set"
+	if m.User != nil && m.User.SelfLimitCents != nil {
+		c := *m.User.SelfLimitCents
+		current = fmt.Sprintf("$%.2f (%d cents)", float64(c)/100, c)
+	}
+
+	out := bodyStyle.Render(wordWrap(
+		"Set your own spending limit. It can only lower the cap on your account, never raise it. Leave blank to remove your limit; 0 blocks all orders.",
+		width,
+	)) + "\n\n"
+	out += labelStyle.Render("Current limit") + "\n"
+	out += m.theme.TextAccent().Render(current) + "\n\n"
+
+	if !m.account.spendLimitFocused {
+		return out + hintStyle.Render("enter: edit limit")
+	}
+
+	box := lipgloss.NewStyle().
+		Border(lipgloss.RoundedBorder()).
+		BorderForeground(m.theme.Highlight()).
+		Width(max(1, width-2))
+	out += labelStyle.Render("New limit (cents)") + "\n"
+	out += box.Render(m.account.spendLimitInput.View())
+	switch {
+	case m.account.spendLimitSaving:
+		out += "\n" + m.theme.TextAccent().Render("saving...")
+	case m.account.spendLimitErr != "":
+		out += "\n" + m.theme.TextError().Render(m.account.spendLimitErr)
+	}
+	out += "\n" + hintStyle.Render("enter: save · esc: cancel")
+	return out
+}
+
+// submitSpendLimit validates the input and, if valid, fires the save command.
+// Validation mirrors the server's write-boundary rules so the user gets instant
+// feedback for the negative/non-numeric cases before any round-trip.
+func (m Model) submitSpendLimit() (Model, tea.Cmd) {
+	cents, err := parseSpendLimitInput(m.account.spendLimitInput.Value())
+	if err != nil {
+		m.account.spendLimitErr = err.Error()
+		return m, nil
+	}
+	m.account.spendLimitErr = ""
+	m.account.spendLimitSaving = true
+	return m, m.setSpendLimitCmd(cents)
+}
+
+// setSpendLimitCmd calls the API off the UI thread and reports back via
+// spendLimitSavedMsg. Mirrors the command shape of createRefundRequestCmd.
+func (m Model) setSpendLimitCmd(cents *int) tea.Cmd {
+	return func() tea.Msg {
+		if m.APIClient == nil || m.User == nil {
+			return spendLimitSavedMsg{Err: fmt.Errorf("not authenticated")}
+		}
+		err := m.APIClient.SetSpendLimit(cents)
+		return spendLimitSavedMsg{Cents: cents, Err: err}
+	}
+}
+
+// parseSpendLimitInput maps the raw input to a *int of cents. Blank clears the
+// limit (nil -> revert to admin/global). "0" is a real "block everything"
+// ceiling, NOT a clear. Negative or non-numeric input is rejected. These rules
+// match the server boundary in api/handlers/account.go:SetSpendLimit.
+func parseSpendLimitInput(s string) (*int, error) {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return nil, nil
+	}
+	n, err := strconv.Atoi(s)
+	if err != nil {
+		return nil, fmt.Errorf("enter a whole number of cents, or blank to clear")
+	}
+	if n < 0 {
+		return nil, fmt.Errorf("limit cannot be negative")
+	}
+	return &n, nil
+}
+
+// defaultAccountFooter is the account-menu footer shown when no sub-view owns
+// the keyboard. Extracted so the spend-limit save/cancel paths can restore it
+// without duplicating the slice.
+func defaultAccountFooter() []footerCommand {
+	return []footerCommand{
+		{key: "j/k", value: "navigate"},
+		{key: "enter", value: "select"},
+		{key: "s", value: "shop"},
+		{key: "c", value: "cart"},
+		{key: "?", value: "help"},
+		{key: "q", value: "quit"},
+	}
+}
+
+// friendlySpendLimitError turns a raw API error into one line of TUI copy.
+// SELF_LIMIT_ABOVE_CAP is the one case worth calling out specifically.
+func friendlySpendLimitError(err error) string {
+	if err == nil {
+		return ""
+	}
+	if strings.Contains(err.Error(), "SELF_LIMIT_ABOVE_CAP") {
+		return "limit can't exceed your account cap"
+	}
+	return "failed to save limit"
+}

pkg/tui/account_test.go

@@ -0,0 +1,115 @@
+package tui
+
+import (
+	"testing"
+
+	tea "charm.land/bubbletea/v2"
+
+	"terminalShop/pkg/models"
+)
+
+func TestParseSpendLimitInput(t *testing.T) {
+	cases := []struct {
+		in      string
+		want    int
+		wantNil bool
+		wantErr bool
+	}{
+		{"", 0, true, false},           // blank clears
+		{"0", 0, false, false},         // 0 is block-all, NOT a clear
+		{"1500", 1500, false, false},   // plain value
+		{"  250  ", 250, false, false}, // trims whitespace
+		{"-5", 0, false, true},         // negative rejected
+		{"abc", 0, false, true},        // non-numeric rejected
+		{"12.5", 0, false, true},       // non-integer rejected
+	}
+	for _, tc := range cases {
+		got, err := parseSpendLimitInput(tc.in)
+		if tc.wantErr {
+			if err == nil {
+				t.Errorf("%q: want error, got value %v", tc.in, got)
+			}
+			continue
+		}
+		if err != nil {
+			t.Errorf("%q: unexpected error: %v", tc.in, err)
+			continue
+		}
+		if tc.wantNil {
+			if got != nil {
+				t.Errorf("%q: want nil, got %d", tc.in, *got)
+			}
+			continue
+		}
+		if got == nil || *got != tc.want {
+			t.Errorf("%q: want %d, got %v", tc.in, tc.want, got)
+		}
+	}
+}
+
+func TestSetSpendLimitCmd_NilClient(t *testing.T) {
+	m := NewModel("test")
+	m.APIClient = nil
+	cmd := m.setSpendLimitCmd(nil)
+	if cmd == nil {
+		t.Fatal("setSpendLimitCmd returned nil cmd")
+	}
+	saved, ok := cmd().(spendLimitSavedMsg)
+	if !ok {
+		t.Fatalf("expected spendLimitSavedMsg, got %T", cmd())
+	}
+	if saved.Err == nil {
+		t.Error("expected error when API client is nil")
+	}
+}
+
+// TestSpendLimitFocusFlow: enter focuses the input and prefills from the user's
+// current limit; esc cancels without mutating the stored limit.
+func TestSpendLimitFocusFlow(t *testing.T) {
+	m := NewModel("test")
+	m = m.updateLayout(100, 40)
+	m, _ = m.AccountSwitch()
+	m.User = &models.User{ID: 1, SelfLimitCents: intp(2500)}
+	for i, item := range models.AccountMenuItems {
+		if item == "spend limit" {
+			m.account.cursor = i
+		}
+	}
+
+	m, _ = m.AccountUpdate(tea.KeyPressMsg{Code: tea.KeyEnter})
+	if !m.account.spendLimitFocused {
+		t.Fatal("enter did not focus the spend-limit input")
+	}
+	if got := m.account.spendLimitInput.Value(); got != "2500" {
+		t.Errorf("prefill: want \"2500\", got %q", got)
+	}
+
+	m, _ = m.AccountUpdate(tea.KeyPressMsg{Code: tea.KeyEsc})
+	if m.account.spendLimitFocused {
+		t.Error("esc did not blur the spend-limit input")
+	}
+	if m.User.SelfLimitCents == nil || *m.User.SelfLimitCents != 2500 {
+		t.Error("esc must not change the stored limit")
+	}
+}
+
+// TestSpendLimitSavedMsg: the async-result handler updates the local user and
+// clears focus on success.
+func TestSpendLimitSavedMsg(t *testing.T) {
+	m := NewModel("test")
+	m = m.updateLayout(100, 40)
+	m, _ = m.AccountSwitch()
+	m.User = &models.User{ID: 1}
+	m.account.spendLimitFocused = true
+	m.account.spendLimitSaving = true
+
+	m, _ = m.AccountUpdate(spendLimitSavedMsg{Cents: intp(750)})
+	if m.account.spendLimitFocused {
+		t.Error("successful save should blur the input")
+	}
+	if m.User.SelfLimitCents == nil || *m.User.SelfLimitCents != 750 {
+		t.Errorf("save should update local user limit to 750, got %v", m.User.SelfLimitCents)
+	}
+}
+
+func intp(i int) *int { return &i }

pkg/tui/model.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"charm.land/bubbles/v2/key"
+	"charm.land/bubbles/v2/textinput"
 	"charm.land/bubbles/v2/viewport"
 	tea "charm.land/bubbletea/v2"
 	"github.com/stripe/stripe-go/v78"
@@ -191,6 +192,10 @@ type accountState struct {
 	cardCursor         int
 	addressDeleting    *int
 	cardDeleting       *int
+	spendLimitFocused  bool
+	spendLimitInput    textinput.Model
+	spendLimitSaving   bool
+	spendLimitErr      string
 	detailViewport     viewport.Model
 	viewportReady      bool
 }

pkg/tui/update.go

@@ -98,9 +98,10 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		}
 		if msg.Data.User.ID != 0 {
 			u := models.User{
-				ID:    msg.Data.User.ID,
-				Name:  msg.Data.User.Email,
-				Email: msg.Data.User.Email,
+				ID:             msg.Data.User.ID,
+				Name:           msg.Data.User.Email,
+				Email:          msg.Data.User.Email,
+				SelfLimitCents: msg.Data.User.SelfLimitCents,
 			}
 			m.User = &u
 			m.Username = u.Name
@@ -176,6 +177,11 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		if m.shipping.form != nil || m.payment.form != nil {
 			break
 		}
+		// spend-limit input owns keys while focused - skip global nav so a
+		// keystroke edits the field instead of switching pages (s/c/a/q/etc...)
+		if m.account.spendLimitFocused {
+			break
+		}
 		// Refund overlay owns input when open; dispatched below before page handlers.
 		if m.refund.open {
 			break