Spec — Dialogs

Facet *isual*do Koder Design. Material parity: https://m3.material.io/components/dialogs.

3 dialog variants

Anatomy (basic)

┌──────────────────────────────────┐
│ [icon?] Title                    │   ← title row
│                                  │
│ Body content — explanation       │   ← body
│ of the decision the user faces.  │
│                                  │
│              [Cancel] [Action]   │   ← actions, right-aligned
└──────────────────────────────────┘
         Scrim overlay (page bg darkened)

• *ontainer* radius-lg (16 px default), surface bg, elevation 5
• *adding* 24 px all sides
• *con*(optional): 24 px above title, accent color
• *itle* headline-small (24/32, weight 600)
• *ody* body-medium (14/20)
• *ctions* button row, right-aligned (or left in RTL), 8 px gap

R1 — Scrim

The semi-transparent overlay behind the dialog.

• Background: rgba(0, 0, 0, 0.5) (light mode) or rgba(0, 0, 0, 0.7) (dark)
• Click on scrim: dismisses dialog (unless nonDismissible: true)
• ESC key: dismisses dialog (unless nonDismissible: true)
• Click on scrim is equivalent to clicking "Cancel" action

Per interaction/states.kmd: animate scrim fade-in (medium duration, decelerate easing) and dialog scale 0.95→1.0 in parallel.

R2 — Full-screen variant

Used on Compact class (per window-size-classes.kmd) or for multi-step flows.

┌──────────────────────────────────┐
│ [X]   Title                  [✓] │   ← app bar w/ close + confirm
├──────────────────────────────────┤
│                                  │
│  Content fills viewport          │
│                                  │
│                                  │
└──────────────────────────────────┘

• App bar at top with close button (left) + confirm action (right)
• Content fills below app bar
• No scrim (it IS the viewport)
• Back navigation per navigation/back-behavior.kmd (back button = dismiss)

R3 — Alert dialog (destructive)

Basic dialog variant specifically for destructive confirms.

• Icon: warning or error glyph in error color
• Title: question form ("Delete 12 messages?")
• Body: consequences ("This cannot be undone.")
• Actions: Cancel (text variant, default focus) + Delete (text or outlined w/ error color)
• Destructive action is RIGHT-aligned (Material convention; some

  guidelines prefer left — Koder follows right)

Default focus: Cancel button (less destructive); Delete requires deliberate tab/click. Prevents accidental confirm on keyboard "Enter".

R4 — Focus trap

When dialog is open:

• Focus moves into the dialog (first focusable element OR explicitly

  designated)

• Tab cycles within dialog only — can't tab to background
• Shift+Tab cycles backward within dialog
• On dismiss: focus returns to the element that opened the dialog

Per koder_kit (Flutter): Dialog widget handles this automatically. Per koder_web_kit: needs explicit focus trap implementation.

R5 — Lifecycle hooks

R6 — Title + body content rules

Per foundations/ux-writing.kmd:

• Title: question form for confirms, statement for info ("Saved.")
• Body: max 200 chars typically; explain the WHY or consequences
• Avoid jargon, avoid hedging ("might", "could possibly")
• Use direct voice ("Your changes are saved.")

R7 — Forbidden patterns

• ❌ Dialog with > 3 actions (use sheet/bottom-sheet instead)
• ❌ Nested dialogs (one at a time — second one replaces first)
• ❌ Auto-dismissing dialog after timer (use snackbar)
• ❌ Modal for non-critical info (use snackbar or tooltip)
• ❌ Dialog with form > 1 short input (use full-screen variant or dedicated page)
• ❌ Disabling close button as the ONLY exit (always provide Cancel/X)

R8 — Accessibility

• role="dialog" + aria-modal="true"
• aria-labelledby pointing to title element id
• aria-describedby pointing to body element id (optional but

  helpful)

• Title is <h2> semantic
• ESC key handler bound
• Focus visible on initial focus + on all interactive elements
• Screen reader announces title + body on open

R9 — Per-preset variation

Cross-link

• foundations/ux-writing.kmd — title + body voice
• navigation/back-behavior.kmd — back/ESC dismissal
• themes/motion.kmd — entry/exit transitions
• themes/elevation.kmd — level 5 default
• errors/user-facing-messages.kmd — error dialog content