Quick Chat viewport layout Requirements

Overview

The Quick Chat dialog contains a tab strip, a transcript, and a chat composer. The transcript can be empty or taller than the available viewport.

The UI system owns this presentation contract. The task system continues to own the conversation data and session lifecycle.

Conversation slot: The area between the Quick Chat tab strip and the bottom edge of the dialog.
Transcript scroll owner: The element that scrolls the Quick Chat message history.
Chat composer: The input area and its toolbar.

Intent: Keep the chat composer reachable while the transcript uses the available dialog height.

User story: As a Quick Chat user, I want the transcript to scroll inside the dialog, so that the chat composer remains visible.

AC-UI-QUICK-CHAT-VIEWPORT-LAYOUT-001.1: When a conversation opens on a tablet or desktop, the conversation slot shall fill the remaining dialog height.
AC-UI-QUICK-CHAT-VIEWPORT-LAYOUT-001.2: When the transcript is short or empty, the chat composer shall stay at the bottom of the conversation slot.
AC-UI-QUICK-CHAT-VIEWPORT-LAYOUT-001.3: When the transcript exceeds the available height, the transcript shall scroll inside its existing scroll owner. The tab strip and chat composer shall remain visible.
AC-UI-QUICK-CHAT-VIEWPORT-LAYOUT-001.4: When the viewport height changes, the dialog shall keep the chat composer inside its lower edge.
AC-UI-QUICK-CHAT-VIEWPORT-LAYOUT-001.5: On a phone viewport, the existing full-height surface shall preserve the same scroll ownership. The chat composer shall remain reachable above the bottom safe area.
AC-UI-QUICK-CHAT-VIEWPORT-LAYOUT-001.6: Given a laptop-height viewport, both a new conversation and a long conversation shall keep the composer inside the dialog. The long transcript shall have scrollable overflow.