fix: render full placeholder text in form inputs

bubbles/v2 textinput truncates the placeholder to its first rune when the
input width is 0 (the default): it sizes the placeholder buffer to
Width()+1 and early-returns after the first character. Set a non-zero
width on every text input (defaultInputWidth) and resize inputs
responsively to the terminal on WindowSizeMsg via FormStep.SetWidth, so
placeholders render in full and inputs fill the available width.

Adds a regression test asserting the placeholder renders past its first
rune.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

internal/tui/form.go

@@ -17,6 +17,11 @@ const (
 	FieldTypeNumber
 )
 
+// defaultInputWidth is the visible width of text inputs before the first window-size
+// message arrives. It must be > 0 (and ideally >= the longest placeholder) so the
+// placeholder renders in full; it is overridden responsively via FormStep.SetWidth.
+const defaultInputWidth = 50
+
 type FormField struct {
 	Id          string
 	Label       string
@@ -51,6 +56,9 @@ func NewFormStep(title string, fields []FormField) FormStep {
 
 		ti := textinput.New()
 		ti.Placeholder = f.Fields[i].Placeholder
+		// A non-zero width is required for the placeholder to render in full: with the
+		// default width of 0 the textinput truncates the placeholder to its first rune.
+		ti.SetWidth(defaultInputWidth)
 		if f.Fields[i].Default != "" {
 			ti.SetValue(f.Fields[i].Default)
 		}
@@ -129,6 +137,17 @@ func (f *FormStep) Values() map[string]string {
 	return out
 }
 
+// SetWidth resizes every text input to w (selects are unaffected). Called on window
+// resize so inputs fill the available terminal width and placeholders render in full.
+func (f *FormStep) SetWidth(w int) {
+	for i := range f.Fields {
+		if f.Fields[i].Type == FieldTypeSelect {
+			continue
+		}
+		f.Fields[i].input.SetWidth(w)
+	}
+}
+
 // View
 func (f FormStep) View() string {
 	pad := strings.Repeat(" ", padding)

internal/tui/form_test.go

@@ -1,6 +1,23 @@
 package tui
 
-import "testing"
+import (
+	"strings"
+	"testing"
+)
+
+// Guards against the bubbles bug where a text input with width 0 renders only the
+// first rune of its placeholder. NewFormStep must set a non-zero width.
+func TestPlaceholderRendersBeyondFirstRune(t *testing.T) {
+	const placeholder = "postgres://user@host/db"
+	f := NewFormStep("t", []FormField{
+		{Id: "url", Label: "URL", Placeholder: placeholder, Type: FieldTypeText},
+	})
+
+	view := f.Fields[0].input.View()
+	if !strings.Contains(view, "ostgres://user@host/db") {
+		t.Errorf("placeholder appears truncated; rendered view = %q", view)
+	}
+}
 
 func TestFormStepValues(t *testing.T) {
 	f := NewFormStep("Test", []FormField{

internal/tui/update.go

@@ -33,6 +33,19 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	case tea.WindowSizeMsg:
 		m.width = msg.Width
 		m.height = msg.Height
+
+		// Fit inputs to the terminal: subtract the left padding, the "> " prompt and
+		// the cursor cell, with a sensible floor for very narrow terminals.
+		inputWidth := msg.Width - (padding * 2) - 4
+		if inputWidth < 20 {
+			inputWidth = 20
+		}
+		for _, f := range []*FormStep{
+			&m.loginForm, &m.wireguardForm, &m.appForm,
+			&m.serverForm, &m.dbForm, &m.certForm,
+		} {
+			f.SetWidth(inputWidth)
+		}
 	case spinner.TickMsg:
 		var cmd tea.Cmd
 		m.spinner, cmd = m.spinner.Update(msg)