refactor(form): replace inline error text with tooltip icon

Instead of rendering error messages as `<small class="form-error">`
below inputs, errors now display as a circle-x icon inside the input
area. Hovering the icon shows the error text in a danger-styled tooltip.

- Wrap children in `.form-field-control` when error is present
- Use existing tooltip + icon components for the error indicator
- Add CSS for positioning, padding-right offset, and danger color overrides
- Update tests to match new structure
- Add pre-commit tmux server check instructions to AGENTS.md

AGENTS.md

@@ -190,9 +190,28 @@ Add the component to all three dev targets so it renders in the visual test page
 ```sh
 bb build-theme   # Regenerate CSS with new component styles
 bb test          # All tests pass
-bb dev-hiccup    # Visual check
 ```
 
+### 6. Check running dev servers before committing — CRITICAL
+
+A tmux session `ui-dev` runs all three dev servers (`bb dev-all`). **Always check every pane for compile errors before committing:**
+
+```sh
+# List panes, then check each for errors
+tmux list-panes -t ui-dev -F "#{pane_index}: #{pane_current_command}"
+for i in $(tmux list-panes -t ui-dev -F "#{pane_index}"); do
+  echo "=== pane $i ==="
+  tmux capture-pane -t "ui-dev:bash.$i" -p -S -30 | grep -v '^$' | tail -10
+done
+```
+
+Look for:
+- **shadow-cljs** (Replicant): `Build failure`, warnings, or `CompilerException`
+- **Vite/Squint**: `ERROR`, `SyntaxError`, or failed imports
+- **Hiccup** (Babashka): stack traces or `Exception`
+
+Do **not** commit if any pane shows errors. Fix them first.
+
 ## Theme System
 
 ### Token naming

src/ui/form.cljc

@@ -1,5 +1,7 @@
 (ns ui.form
-  (:require [clojure.string :as str]))
+  (:require [clojure.string :as str]
+            [ui.icon :as icon]
+            [ui.tooltip :as tooltip]))
 
 ;; In squint, keywords are strings — name is identity
 #?(:squint (defn- kw-name [s] s)
@@ -19,6 +21,12 @@
   [opts]
   (str/join " " (form-field-class-list opts)))
 
+(defn- error-icon
+  "Render a circle-x icon wrapped in a tooltip showing the error text."
+  [error]
+  (tooltip/tooltip {:text error :class "form-error-icon"}
+    (icon/icon {:icon-name :circle-x :size :sm})))
+
 (defn form-field
   "Render a form field wrapper with label, hint, and error support.
 
@@ -37,9 +45,11 @@
              (cond-> (if label
                        [[:label {:class "form-label"} label]]
                        [])
-               true (into children)
-               hint  (conj [:small {:class "form-hint"} hint])
-               error (conj [:small {:class "form-error"} error]))))
+               true (into (if error
+                            [(into [:div {:class "form-field-control"}]
+                                   (conj (vec children) (error-icon error)))]
+                            children))
+               hint (conj [:small {:class "form-hint"} hint]))))
 
      :cljs
      (let [cls (form-field-class-list {:error error})
@@ -49,9 +59,11 @@
              (cond-> (if label
                        [[:label {:class ["form-label"]} label]]
                        [])
-               true (into children)
-               hint  (conj [:small {:class ["form-hint"]} hint])
-               error (conj [:small {:class ["form-error"]} error]))))
+               true (into (if error
+                            [(into [:div {:class ["form-field-control"]}]
+                                   (conj (vec children) (error-icon error)))]
+                            children))
+               hint (conj [:small {:class ["form-hint"]} hint]))))
 
      :clj
      (let [classes (cond-> (form-field-classes {:error error})
@@ -61,9 +73,11 @@
              (cond-> (if label
                        [[:label {:class "form-label"} label]]
                        [])
-               true (into children)
-               hint  (conj [:small {:class "form-hint"} hint])
-               error (conj [:small {:class "form-error"} error]))))))
+               true (into (if error
+                            [(into [:div {:class "form-field-control"}]
+                                   (conj (vec children) (error-icon error)))]
+                            children))
+               hint (conj [:small {:class "form-hint"} hint]))))))
 
 ;; ── Text input ──────────────────────────────────────────────────────
 

src/ui/form.css

@@ -240,16 +240,63 @@
   cursor: not-allowed;
 }
 
-/* ── Hint & Error text ─────────────────────────────────────────── */
+/* ── Hint text ─────────────────────────────────────────────────── */
 
 .form-hint {
   font-size: var(--font-xs);
   color: var(--fg-2);
 }
 
-.form-error {
-  font-size: var(--font-xs);
+/* ── Error icon with tooltip ───────────────────────────────────── */
+
+.form-field-control {
+  position: relative;
+}
+
+.form-field-control > .form-input,
+.form-field-control > .form-textarea,
+.form-field-control > .form-select {
+  padding-right: var(--size-8);
+}
+
+.tooltip.form-error-icon {
+  position: absolute;
+  right: var(--size-2);
+  top: 0;
+  bottom: 0;
+  display: flex;
+  align-items: center;
   color: var(--danger);
+  cursor: pointer;
+  z-index: 1;
+}
+
+.tooltip.form-error-icon::after {
+  background: color-mix(in srgb, var(--danger) 18%, var(--bg-1));
+  color: var(--fg-0);
+  border: 1px solid color-mix(in srgb, var(--danger) 25%, transparent);
+  white-space: normal;
+  min-width: 12rem;
+  max-width: 20rem;
+  line-height: 1.4;
+  left: auto;
+  right: 0;
+  transform: translateY(4px);
+}
+
+.tooltip.form-error-icon:hover::after {
+  transform: translateY(0);
+}
+
+.tooltip.form-error-icon::before {
+  border-top-color: color-mix(in srgb, var(--danger) 18%, var(--bg-1));
+  left: auto;
+  right: var(--size-1);
+  transform: translateY(4px);
+}
+
+.tooltip.form-error-icon:hover::before {
+  transform: translateY(0);
 }
 
 /* ── Fieldset & Legend ──────────────────────────────────────────── */

test/ui/form_test.clj

@@ -32,11 +32,19 @@
       (is (some #(and (vector? %) (= :small (first %)) (= "form-hint" (get-in % [1 :class])))
                 result))))
 
-  (testing "renders error text"
+  (testing "renders error icon with tooltip"
     (let [result (form/form-field {:label "Email" :error "Invalid email"} [:input])]
       (is (= "form-field form-field--error" (get-in result [1 :class])))
-      (is (some #(and (vector? %) (= :small (first %)) (= "form-error" (get-in % [1 :class])))
-                result))))
+      ;; Children wrapped in form-field-control
+      (let [control (nth result 3)]
+        (is (= :div (first control)))
+        (is (= "form-field-control" (get-in control [1 :class])))
+        ;; Contains the child input
+        (is (= :input (first (nth control 2))))
+        ;; Contains the tooltip with error text
+        (let [tip (nth control 3)]
+          (is (= :span (first tip)))
+          (is (= "Invalid email" (get-in tip [1 :data-tooltip])))))))
 
   (testing "no label renders without label element"
     (let [result (form/form-field {} [:input])]