# Component cookbook

GROWS every migration. Each entry: what it is, the swap rule it uses, and the canonical
snippet. Reuse these before writing anything new; the success signal is *more reuse each
migration*.

Seeded from `transaction/edit.clj` (Hiccup form — Selmer versions land in Phase 2).

---

## typeahead (account / vendor) — Alpine + tippy, survives swaps

Used for account and vendor selection. Click-to-select (not a live text caret), so a
whole-form swap on change is safe. Null-guard `tippy?`/`$refs.input?`.

```clojure
(defn account-typeahead* [{:keys [name value client-id x-model]}]
  [:div.flex.flex-col
   (com/typeahead {:name name
                   :placeholder "Search..."
                   :url (hu/url (bidi/path-for ssr-routes/only-routes :account-search)
                                (cond-> {:purpose "transaction"} client-id (assoc :client-id client-id)))
                   :id name
                   :x-model x-model            ; binds selected value into the row's Alpine scope
                   :value value
                   :content-fn (fn [v] (:account/name (d-accounts/clientize ... v client-id)))})])
```
Reuse note: `:x-model` lets the *parent* row read the selected id (e.g. `accountId`) to
gate a targeted location swap. See account-row.

## account-row — cursor render fn + per-row targeted location swap + whole-form remove

The canonical "row in a repeated grid" pattern. One render fn, top-rooted cursor.
- account typeahead binds `accountId` into row Alpine scope;
- **location cell** swaps *only itself* (`#account-location-<index>`) on `changed`
  (swap-doctrine Rule 2);
- **amount cell** swaps *only* `#account-totals` (Rule 4, sibling tbody);
- **remove** swaps the whole form (Rule 3).

```clojure
(defn transaction-account-row* [{:keys [value client-id amount-mode index]}]
  (com/data-grid-row
   (-> {:class "account-row" :id (str "account-row-" index)
        :x-data (hx/json {:show ... :accountId (fc/field-value (:transaction-account/account value))})
        :data-key "show" :x-ref "p"}
       hx/alpine-mount-then-appear)
   (fc/with-field :db/id (com/hidden {:name (fc/field-name) :value (fc/field-value)}))
   (fc/with-field :transaction-account/account
     (com/data-grid-cell {} (com/validated-field {:errors (fc/field-errors)}
       (account-typeahead* {:value (fc/field-value) :client-id client-id
                            :name (fc/field-name) :x-model "accountId"}))))
   (fc/with-field :transaction-account/location
     (com/data-grid-cell {:id (str "account-location-" index)} ...Rule 2 targeted swap...))
   (fc/with-field :transaction-account/amount
     (com/data-grid-cell {} ...Rule 4 totals swap...))
   (com/data-grid-cell {:class "align-top"} ...Rule 3 whole-form remove...)))
```
TODO Phase 2: drop the `transaction-account-row-no-cursor*` twin; this is the only kept form.

## totals in a sibling `<tbody>` — Rule 4 instead of OOB

Running totals live in their own `<tbody id="account-totals">`, a sibling of the
input-bearing rows, so an amount edit refreshes them with a plain targeted swap and never
replaces the amount input (caret survives).

```clojure
(com/data-grid
 {:footer-tbody
  [:tbody {:id "account-totals"}
   (com/data-grid-row {:class "account-total-row"} ... (account-total* request) ...)
   (com/data-grid-row {:class "account-balance-row"} ... (account-balance* request) ...)]}
 ...input rows...)
```

## money-input / text-input amount field — Rule 4 targeted totals swap

```clojure
(com/money-input
 {:name (fc/field-name) :id (str "account-amount-" index) :class "w-16 account-amount-field"
  :hx-post (bidi/path-for ssr-routes/only-routes ::route/edit-form-changed)
  :hx-target "#account-totals" :hx-select "#account-totals" :hx-swap "outerHTML"
  :hx-trigger "keyup changed delay:300ms" :hx-include "closest form"})
```
`%` mode swaps to `com/text-input {:type "number" :step "0.01"}` with the same swap attrs.

## memo field — Rule 1, no request

```clojure
(com/text-input {:value (fc/field-value) :name (fc/field-name) :id "edit-memo"
                 :placeholder "Optional note"})   ; no hx-* — rides along to save
```

## mode toggle ($/% radio, simple/advanced link) — Rule 3, whole-form swap

```clojure
(com/radio-card {:options [{:value "$" :content "$"} {:value "%" :content "%"}]
                 :value amount-mode :name "step-params[amount-mode]"
                 :hx-post (bidi/path-for ssr-routes/only-routes ::route/toggle-amount-mode)
                 :hx-target "#wizard-form" :hx-select "#wizard-form" :hx-swap "outerHTML"
                 :hx-include "closest form"})
```
TODO Phase 2: the simple/advanced toggle becomes a `?mode=` re-render (plain form), not a
dedicated route.