feat(finance): interactive waterfall + goal auto-tag + free cash prompt

- Waterfall now drills down: click Income/Living/Goals to expand
  category breakdown, click a category to see its transactions
- Goal contributions are now transaction-backed (GoalID on Transaction,
  SavedCents derived from MongoDB aggregation)
- Dashboard goals widget shows this-month funding status per goal
- Goals page lists funding history transactions per goal
- Transactions modal accepts a goal pre-selection (?fund_goal=<id>)
- Categories can auto-tag a linked goal on expense creation
- Settings → categories shows linked goal column and edit modal
- Free cash "what now?" section lists underfunded committed goals
  with shortfall and Fund → links; shows success state when all met
- i18n: full EN/PT coverage for all new keys
- Seed data includes goal-tagged transactions so progress is non-zero
- Bug fixes: ImpactOnDisposable double-subtraction, avgMonthlySavings
  denominator using only positive-savings months, cross-year month key

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

apps/finance/services/api/main/handler.go

@@ -849,6 +849,19 @@ func (h *Handler) CreateTransaction(w http.ResponseWriter, r *http.Request) {
 		date = time.Now()
 	}
 
+	// Auto-tag: if no explicit goal_id but the category has one linked, inherit it.
+	goalID := body.GoalID
+	if goalID == "" && body.Category != "" && body.AmountCents < 0 {
+		if cats, err2 := h.store.getCategories(ctx, a.UserID); err2 == nil {
+			for _, c := range cats {
+				if c.Name == body.Category && c.GoalID != "" {
+					goalID = c.GoalID
+					break
+				}
+			}
+		}
+	}
+
 	txn := Transaction{
 		ID:          bson.NewObjectID().Hex(),
 		UserID:      a.UserID,
@@ -857,7 +870,7 @@ func (h *Handler) CreateTransaction(w http.ResponseWriter, r *http.Request) {
 		Description: body.Description,
 		AmountCents: body.AmountCents,
 		Category:    body.Category,
-		GoalID:      body.GoalID,
+		GoalID:      goalID,
 		CreatedAt:   time.Now(),
 	}
 
@@ -1300,6 +1313,7 @@ func (h *Handler) Categories(w http.ResponseWriter, r *http.Request) {
 			Name        string `json:"name"`
 			Color       string `json:"color"`
 			BudgetCents int64  `json:"budget_cents"`
+			GoalID      string `json:"goal_id"`
 		}
 		if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
 			http.Error(w, "bad request", http.StatusBadRequest)
@@ -1311,6 +1325,7 @@ func (h *Handler) Categories(w http.ResponseWriter, r *http.Request) {
 			Name:        body.Name,
 			Color:       body.Color,
 			BudgetCents: body.BudgetCents,
+			GoalID:      body.GoalID,
 		}
 		if err := h.store.updateCategory(r.Context(), cat); err != nil {
 			slog.Error("update category", "err", err)
@@ -2710,16 +2725,24 @@ func (h *Handler) Settings(w http.ResponseWriter, r *http.Request) {
 
 	accounts, _ := h.store.getAccounts(ctx, a.UserID)
 	categories, _ := h.store.getCategories(ctx, a.UserID)
+	goals, _ := h.store.getGoals(ctx, a.UserID)
+
+	goalNameByID := make(map[string]string, len(goals))
+	for _, g := range goals {
+		goalNameByID[g.ID] = g.Name
+	}
 
 	render(w, settingsTmpl, &SettingsData{
-		T:          h.t(r),
+		T:            h.t(r),
-		UserID:     a.UserID,
+		UserID:       a.UserID,
-		Email:      a.Email,
+		Email:        a.Email,
-		Title:      "Settings",
+		Title:        "Settings",
-		Route:      "settings",
+		Route:        "settings",
-		Tab:        tab,
+		Tab:          tab,
-		Accounts:   accounts,
+		Accounts:     accounts,
-		Categories: categories,
+		Categories:   categories,
+		Goals:        goals,
+		GoalNameByID: goalNameByID,
 	})
 }
 

apps/finance/services/api/main/locales/en.toml

@@ -258,6 +258,9 @@ goals                   = "Goal contributions"
 goals_link              = "manage →"
 free_cash               = "Free cash"
 month_progress          = "Month progress"
+what_now                = "What now?"
+fund_link               = "Fund"
+all_funded              = "All committed goals funded this month ✓"
 
 # ── Transactions ─────────────────────────────────────────────────────────────
 
@@ -830,6 +833,7 @@ placeholder_budget  = "Monthly budget (cents)"
 btn_add             = "Add"
 col_category        = "Category"
 col_budget          = "Monthly Budget"
+col_goal            = "Auto-tags goal"
 btn_delete          = "Delete"
 empty_msg           = "No categories yet — add one above."
 confirm_delete      = "Delete this category?"
@@ -838,6 +842,9 @@ confirm_delete      = "Delete this category?"
 title               = "Edit Category"
 placeholder_name    = "Name"
 placeholder_budget  = "Budget (cents)"
+label_goal          = "Auto-tag goal"
+option_no_goal      = "— none —"
+goal_hint           = "Expenses in this category will automatically fund the selected goal."
 btn_cancel          = "Cancel"
 btn_save            = "Save"
 

apps/finance/services/api/main/locales/pt.toml

@@ -258,6 +258,9 @@ goals                   = "Contribuições para objetivos"
 goals_link              = "gerir →"
 free_cash               = "Dinheiro livre"
 month_progress          = "Progresso do mês"
+what_now                = "E agora?"
+fund_link               = "Financiar"
+all_funded              = "Todos os objetivos comprometidos financiados este mês ✓"
 
 # ── Transações ────────────────────────────────────────────────────────────────
 
@@ -830,6 +833,7 @@ placeholder_budget  = "Orçamento mensal (cêntimos)"
 btn_add             = "Adicionar"
 col_category        = "Categoria"
 col_budget          = "Orçamento Mensal"
+col_goal            = "Etiqueta automática"
 btn_delete          = "Eliminar"
 empty_msg           = "Sem categorias ainda — adicione uma acima."
 confirm_delete      = "Eliminar esta categoria?"
@@ -838,6 +842,9 @@ confirm_delete      = "Eliminar esta categoria?"
 title               = "Editar Categoria"
 placeholder_name    = "Nome"
 placeholder_budget  = "Orçamento (cêntimos)"
+label_goal          = "Etiquetar objetivo automaticamente"
+option_no_goal      = "— nenhum —"
+goal_hint           = "As despesas nesta categoria irão financiar automaticamente o objetivo selecionado."
 btn_cancel          = "Cancelar"
 btn_save            = "Guardar"
 

apps/finance/services/api/main/models.go

@@ -34,11 +34,13 @@ type Account struct {
 }
 
 type Category struct {
-	ID         string `bson:"_id" json:"id"`
+	ID          string `bson:"_id" json:"id"`
-	UserID     string `bson:"user_id" json:"user_id"`
+	UserID      string `bson:"user_id" json:"user_id"`
-	Name       string `bson:"name" json:"name"`
+	Name        string `bson:"name" json:"name"`
-	Color      string `bson:"color" json:"color"`
+	Color       string `bson:"color" json:"color"`
-	BudgetCents int64 `bson:"budget_cents" json:"budget_cents"`
+	BudgetCents int64  `bson:"budget_cents" json:"budget_cents"`
+	// GoalID, when set, auto-tags transactions in this category to the linked goal.
+	GoalID string `bson:"goal_id,omitempty" json:"goal_id,omitempty"`
 }
 
 type Transaction struct {
@@ -322,6 +324,8 @@ type SettingsData struct {
 	Tab        string // "accounts" | "categories"
 	Accounts   []Account
 	Categories []Category
+	Goals      []Goal            // for category → goal linking dropdown
+	GoalNameByID map[string]string // goalID → name, for table display
 }
 
 type HouseholdData struct {

apps/finance/services/api/main/store.go

@@ -103,11 +103,13 @@ func (s *Store) createCategory(ctx context.Context, c *Category) error {
 func (s *Store) updateCategory(ctx context.Context, c *Category) error {
 	ctx, span := mongo.StartSpan(ctx, "Store.updateCategory")
 	defer span.End()
-	_, err := s.categories().UpdateOne(ctx, bson.M{"_id": c.ID, "user_id": c.UserID}, bson.M{"$set": bson.M{
+	update := bson.M{
-		"name":        c.Name,
+		"name":         c.Name,
-		"color":       c.Color,
+		"color":        c.Color,
 		"budget_cents": c.BudgetCents,
-	}})
+		"goal_id":      c.GoalID, // "" clears the link
+	}
+	_, err := s.categories().UpdateOne(ctx, bson.M{"_id": c.ID, "user_id": c.UserID}, bson.M{"$set": update})
 	return err
 }
 

apps/finance/services/api/main/templates/dashboard.html

@@ -153,6 +153,29 @@
            background:var(--text3); transition:width 1s ease;"></div>
     </div>
   </div>
+
+  <!-- What now? prompt — underfunded committed goals -->
+  {{if $d.DashGoals}}
+  <div style="margin-top:16px; padding-top:14px; border-top:1px solid var(--border);">
+    <div style="font-size:11px; font-weight:700; color:var(--muted); text-transform:uppercase; letter-spacing:0.06em; margin-bottom:8px;">{{$d.T.Get "dashboard.waterfall.what_now"}}</div>
+    <div id="wf-what-now-list">
+      {{range $d.DashGoals}}
+      {{if .Committed}}
+        {{$funded := index $d.GoalFundedThisMonth .ID}}
+        {{$needed := .MonthlyCents}}
+        {{if lt $funded $needed}}
+        {{$shortfall := sub $needed $funded}}
+        <div style="display:flex; justify-content:space-between; align-items:center; padding:5px 0; font-size:13px;">
+          <span style="color:var(--text2);">{{.Name}} <span style="color:var(--red);">−€{{cents $shortfall}}</span></span>
+          <a href="/transactions?fund_goal={{.ID}}" style="font-size:12px; color:var(--accent); text-decoration:none; font-weight:600;">{{$d.T.Get "dashboard.waterfall.fund_link"}} →</a>
+        </div>
+        {{end}}
+      {{end}}
+      {{end}}
+    </div>
+    <div id="wf-all-funded" style="display:none; font-size:13px; color:var(--green);">{{$d.T.Get "dashboard.waterfall.all_funded"}}</div>
+  </div>
+  {{end}}
 </div>
 
 <style>
@@ -215,6 +238,11 @@ function wfToggleCat(id) {
   list.style.display = open ? 'none' : 'block';
   if (chev) chev.classList.toggle('open', !open);
 }
+(function() {
+  const list = document.getElementById('wf-what-now-list');
+  const allFunded = document.getElementById('wf-all-funded');
+  if (list && allFunded && !list.children.length) allFunded.style.display = '';
+})();
 </script>
 
 <!-- 3 diagnostic cards -->

apps/finance/services/api/main/templates/settings.html

@@ -87,7 +87,12 @@ tr:last-child td { border-bottom:none; }
 <div class="s-card">
   {{if $d.Categories}}
   <table>
-    <thead><tr><th>{{$d.T.Get "settings.categories.col_category"}}</th><th style="text-align:right;">{{$d.T.Get "settings.categories.col_budget"}}</th><th></th></tr></thead>
+    <thead><tr>
+      <th>{{$d.T.Get "settings.categories.col_category"}}</th>
+      <th style="text-align:right;">{{$d.T.Get "settings.categories.col_budget"}}</th>
+      {{if $d.Goals}}<th style="text-align:left; padding-left:12px; font-size:12px;">{{$d.T.Get "settings.categories.col_goal"}}</th>{{end}}
+      <th></th>
+    </tr></thead>
     <tbody>
     {{range $d.Categories}}
     <tr id="cat-row-{{.ID}}">
@@ -101,9 +106,19 @@ tr:last-child td { border-bottom:none; }
         {{else}}
         <span id="cat-budget-{{.ID}}" style="color:var(--muted);">—</span>
         {{end}}
-        <button onclick="editCat('{{.ID}}','{{.Name}}',{{.BudgetCents}},'{{.Color}}')"
+        <button onclick="editCat('{{.ID}}','{{.Name}}',{{.BudgetCents}},'{{.Color}}','{{.GoalID}}')"
                 style="margin-left:8px; background:none; border:none; cursor:pointer; color:var(--muted); font-size:0.85rem;">✎</button>
       </td>
+      {{if $d.Goals}}
+      <td style="padding-left:12px;">
+        {{$goalName := index $d.GoalNameByID .GoalID}}
+        {{if $goalName}}
+        <span id="cat-goal-{{.ID}}" style="font-size:12px; color:var(--accent);">⚡ {{$goalName}}</span>
+        {{else}}
+        <span id="cat-goal-{{.ID}}" style="font-size:12px; color:var(--muted);">—</span>
+        {{end}}
+      </td>
+      {{end}}
       <td style="text-align:right;">
         <button class="btn btn-danger" onclick="deleteCat('{{.ID}}')">{{$d.T.Get "settings.categories.btn_delete"}}</button>
       </td>
@@ -129,6 +144,18 @@ tr:last-child td { border-bottom:none; }
       <input id="edit-cat-name"   type="text"   placeholder="{{$d.T.Get "settings.categories.modal_edit.placeholder_name"}}" style="padding:8px 12px; border:1px solid var(--border); border-radius:8px; background:var(--bg); color:var(--text);">
       <input id="edit-cat-budget" type="number" placeholder="{{$d.T.Get "settings.categories.modal_edit.placeholder_budget"}}" min="0" style="padding:8px 12px; border:1px solid var(--border); border-radius:8px; background:var(--bg); color:var(--text);">
       <input id="edit-cat-color"  type="color"  style="width:100%; height:38px; padding:4px; border:1px solid var(--border); border-radius:8px; cursor:pointer;">
+      {{if $d.Goals}}
+      <div>
+        <label style="font-size:12px; color:var(--muted); display:block; margin-bottom:4px;">{{$d.T.Get "settings.categories.modal_edit.label_goal"}}</label>
+        <select id="edit-cat-goal" style="width:100%; padding:8px 12px; border:1px solid var(--border); border-radius:8px; background:var(--bg); color:var(--text);">
+          <option value="">{{$d.T.Get "settings.categories.modal_edit.option_no_goal"}}</option>
+          {{range $d.Goals}}
+          <option value="{{.ID}}">{{.Name}}</option>
+          {{end}}
+        </select>
+        <p style="font-size:11px; color:var(--muted); margin-top:4px;">{{$d.T.Get "settings.categories.modal_edit.goal_hint"}}</p>
+      </div>
+      {{end}}
     </div>
     <div style="display:flex; gap:8px; justify-content:flex-end; margin-top:16px;">
       <button onclick="closeEditCat()" class="btn" style="background:var(--bg); border:1px solid var(--border); color:var(--text);">{{$d.T.Get "settings.categories.modal_edit.btn_cancel"}}</button>
@@ -154,11 +181,13 @@ function deleteCat(id) {
     .then(r => { if (r.ok) location.reload(); });
 }
 
-function editCat(id, name, budgetCents, color) {
+function editCat(id, name, budgetCents, color, goalID) {
   editingCatID = id;
   document.getElementById('edit-cat-name').value   = name;
   document.getElementById('edit-cat-budget').value = budgetCents || '';
   document.getElementById('edit-cat-color').value  = color || '#6366f1';
+  const goalSel = document.getElementById('edit-cat-goal');
+  if (goalSel) goalSel.value = goalID || '';
   document.getElementById('edit-cat-modal').style.display = 'flex';
 }
 
@@ -169,13 +198,17 @@ function closeEditCat() {
 
 function saveEditCat() {
   if (!editingCatID) return;
-  const body = new URLSearchParams({
+  const goalSel = document.getElementById('edit-cat-goal');
-    name:         document.getElementById('edit-cat-name').value,
+  fetch('/categories/' + editingCatID, {
-    budget_cents: document.getElementById('edit-cat-budget').value || '0',
+    method: 'PUT',
-    color:        document.getElementById('edit-cat-color').value,
+    headers: {'Content-Type': 'application/json'},
-  });
+    body: JSON.stringify({
-  fetch('/categories/' + editingCatID, { method: 'PUT', body })
+      name:         document.getElementById('edit-cat-name').value,
-    .then(r => { if (r.ok) { closeEditCat(); location.reload(); } });
+      budget_cents: parseInt(document.getElementById('edit-cat-budget').value || '0'),
+      color:        document.getElementById('edit-cat-color').value,
+      goal_id:      goalSel ? goalSel.value : '',
+    }),
+  }).then(r => { if (r.ok) { closeEditCat(); location.reload(); } });
 }
 
 document.getElementById('add-account-form')?.addEventListener('submit', function(e) {