🤖 Tutorial bubble: hand focus over when a covering panel closes, and Tab from the composer to the bubble #7198

Follow-up split out of #7170 (#7114). Impact 1. Two Codex findings from the PR's review round 5, deferred because that round fixes only blockers.

Background

#7170 stops the tutorial bubble from taking keyboard focus in two cases: when a text field (the composer) has focus, and when a full-screen layer (Artifacts, App View) covers the bubble. The bubble stays visible and clickable, and Escape on the bubble still skips the tutorial once the bubble has focus.

Problem 1: focus is not handed over when the covering panel closes

useBubbleFocus (src/browser/components/TutorialTooltip/TutorialTooltip.tsx) runs once, when the bubble is positioned. If a full-screen panel covers the bubble at that moment, the hook leaves focus alone. When the panel leaves full-screen, both panel implementations move focus back to their own panel, so the now-visible bubble never gets focus. The user must click or Tab to the bubble before Escape skips it.

Problem 2: Tab from the composer does not reach the bubble next

In the creation flow, focus stays in the composer. The bubble is portaled after the app tree with tabIndex={-1}, so Tab from the composer goes through the composer's mode and model controls and the rest of the page before it reaches Skip or Next.

Acceptance

• When the layer that covered the bubble goes away, the bubble takes focus, unless a text field has focus.
• From a focused composer, the next Tab reaches the bubble (for example, a focus sentinel or an explicit Tab handoff), and Shift+Tab from the bubble returns to the composer.
• Bun tests in TutorialTooltip.test.tsx cover both. The 🤖 Escape does not close the tutorial tooltip #5701 repro (tests/bugbash/repros/tutorialEscapeOverSettings.e2e.ts) still passes.

Generated with xum • Model: anthropic:claude-opus-5-5 • Thinking: high • Cost: $64.46