M1 — Single SessionProvider via nested router.
The previous router had two route entries with `path: '/'`
(Navigate, AppShell) plus a separate `/login` entry, each wrapped in
its own RootLayout. That instantiated SessionProvider three times,
forking state the moment session writes diverged across siblings.
Replaced by one Root route with SessionProvider + <Outlet />, and
index/login/AppShell-children nested underneath. RootLayout (the
per-tree wrapper) is now obsolete and deleted; the new Root component
lives in src/routing/Root.tsx (addresses NIT N4 as a side effect).
M2 — Typo: "pollign" → "polling" in LiveCockpitPage masthead.
M3 — Replace asymmetric `?? 'rt_operator'` / `?? 'soc_analyst'`
fallbacks in LiveCockpitPage with an explicit `if (!user) return null;`
guard placed after all hooks (rules-of-hooks). AppShell already
redirects unauthenticated visitors to /login, so the guard documents
the invariant rather than introducing one.
NITs N1-N3, N5-N7 recorded in tasks/todo.md as sprint 1+ follow-ups.
- Role enum (rt_operator, rt_lead, soc_analyst) aligned with spec §3 / F11.
Frontend predicates (isRT, isLead, isSOC) drive layout only — backend
remains the source of truth for permissions (D-008).
- SessionContext split into Provider (TSX) and hook (useSession) to satisfy
react-refresh/only-export-components.
- AppShell composes StatusRail (link health, active run, UTC clock, build) +
Sidebar (role-conditional nav with keyboard shortcut hints) + Outlet.
Unauthenticated visitors redirect to /login.
- StatusRail uses pulsing status-dot pattern and label-system micro-typo
(uppercase 10px, 0.08em tracking) to evoke an instrument-panel header.
- Router (createBrowserRouter): /login outside the shell, all app routes
nested inside the shell. RootLayout extracted to its own file for
fast-refresh compliance.
Routes (sprint 0, flat):
/login LoginPage
/engagements EngagementsPage
/library TtpLibraryPage (RT only — gated client-side, will
be re-enforced by backend RBAC)
/scenarios ScenarioComposerPage (RT only)
/runs LiveCockpitPage
/reports ReportPage
/audit AuditPage (lead RT only)
Sub-routes under /engagements/:eid land in sprint 1+ when real scoping
arrives.
