Gap 1 — WS_URL now derives from NEXT_PUBLIC_PLATFORM_URL when
NEXT_PUBLIC_WS_URL is not set (http→ws, appends /ws; https→wss).
Operators need only one env var. NEXT_PUBLIC_WS_URL remains an explicit
override escape hatch.
Gap 2 — Add canvas/.env.example documenting NEXT_PUBLIC_PLATFORM_URL
(required) and NEXT_PUBLIC_WS_URL (optional override, commented out).
Gap 3 — Toolbar fires showToast("Live updates restored", "success")
when wsStatus transitions connecting→connected. mountedRef (set after
2 s) suppresses the toast on the very first page-load connection so
only genuine reconnects notify the user.
Gap 4 — New canvas/src/store/__tests__/socket.url.test.ts (6 tests):
· fallback to ws://localhost:8080/ws when no env set
· http→ws derivation from NEXT_PUBLIC_PLATFORM_URL
· https→wss derivation
· NEXT_PUBLIC_WS_URL override takes precedence
· api.ts PLATFORM_URL fallback
· api.ts reads NEXT_PUBLIC_PLATFORM_URL
375/375 tests passing, production build clean.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
