Task-by-task implementation plan for Phase 8 of the Nexus layout
overhaul (docs/specs/2026-04-11-nexus-layout-overhaul.md §13).
Seven tasks:
1. IconRail component + test
2. ModeBreadcrumb component + test
3. CmdKButton shim component + test
4. GlobalMicButton scaffold + test
5. TopStrip composite + test
6. Layout.tsx rewrite (mount new frame, kill old chrome)
7. Manual smoke test
TDD throughout (write failing test, run, implement, run, commit).
One commit per task. Execution via subagent-driven-development with
fresh subagent per task and two-stage review.
The plan includes complete code for every task (no placeholders),
exact file paths, exact test patterns matching the existing vitest
manual-createRoot pattern from ChatInput.test.tsx, and wire-up
details for preserving Layout.tsx's non-chrome responsibilities
(company-prefix URL sync, first-run onboarding, body overflow,
instance settings memory, dialog overlays).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2a42f4ab86