Fix JetBrains Session Question Scroll

Goal

When a question-like active view first appears in the JetBrains session UI, do not auto-scroll the transcript if the user is already away from the tail and the scroll-to-bottom button is visible. This applies to permission prompts and question-based views. Existing behavior should remain: if the transcript is already at the bottom, new questions/permissions keep the view at the bottom; explicit question navigation can still jump to the active card.

Current Findings

• SessionUi wires QuestionView with:
  • follow = { scroll.following() }
  • scroll = { scroll.followBottom(it) }
• QuestionView.show() runs on first display and calls:
  • val tail = follow() before rendering the card
  • scroll(tail) after rendering
• SessionScroll.following() currently returns component.viewport.view === messages && tail.
• This can use stale internal follow state instead of the live scrollbar state. The user-visible condition is better represented by SessionScroll.atBottom(), which is also what SessionController.beforeUpdate uses for normal transcript updates.
• Existing SessionScrollTest already covers question and login-required middle-scroll preservation, but it does not cover permission first appearance and likely does not cover a stale-tail/live-not-at-bottom edge.

Implementation Plan

1. Update question first-show follow sampling to use live bottom state.

   • In SessionUi.buildUi(), change the QuestionView follow lambda from scroll.following() to scroll.atBottom().
   • Alternatively, if a single semantic API is preferred, change SessionScroll.following() to return component.viewport.view === messages && atBottom() and keep the SessionUi call site unchanged. Prefer the smaller, clearer call-site change unless tests show other following() behavior should change too.

2. Add permission scroll regression tests in SessionScrollTest.

   • Add test permission appearing at bottom keeps scroll at bottom.
   • Add test permission appearing while user is in middle preserves scroll position.
   • Emit ChatEventDto.PermissionAsked("ses_test", PermissionRequestDto(...)) using the same DTO style as the existing recovered permission test.
   • Assert the scrollbar value is preserved and jumpButton().isVisible stays true when initially away from bottom.

3. Strengthen question regression coverage if needed.

   • Keep the existing test question appearing while user is in middle preserves scroll position.
   • If the bug reproduces only when the jump button is visible but tail can be stale, add a targeted regression that creates the visible jump state before QuestionAsked and asserts first display does not jump.
   • Avoid adding production-only test hooks; use existing setValue, setValuePassive, drainScroll, and event helpers.

4. Preserve intentional explicit navigation behavior.

   • Do not change QuestionView.goForward(), goBack(), or goReview(), which intentionally call scroll(true) and are covered by existing tests that expect navigation to jump to the active question card.
   • Do not change prompt growth or normal streaming follow behavior unless a failing test shows the same stale-state issue applies there.

5. Verification.

   • Run the targeted JetBrains frontend session scroll tests from packages/kilo-jetbrains/ using Gradle test filtering for SessionScrollTest if supported.
   • Run ./gradlew typecheck from packages/kilo-jetbrains/ if the targeted tests pass or if Gradle filtering is unavailable.
   • If Java 21 is unavailable, first check/report that blocker as instructed by the repo docs.

Expected Files To Touch

• packages/kilo-jetbrains/frontend/src/main/kotlin/ai/kilocode/client/session/SessionUi.kt
• packages/kilo-jetbrains/frontend/src/test/kotlin/ai/kilocode/client/session/SessionScrollTest.kt

Non-Goals

• No backend or RPC protocol changes.
• No redesign of the session scroll algorithm.
• No changes to explicit question navigation auto-scroll behavior.