PvZ 2-6 guide identity

The native source story hands Dave's role to his brother and later brings Dave back. Previously the host had no observation of those changes. A compatible client can now send source40164's existing guideRole (0 or 1), advertised by source26-guide-v1. The prompt follows the current original/Blue Dave role; past dialogue and planned handoffs cannot establish it. No new action, persistent state, save schema or account setting is introduced.

Old clients may omit the field. New clients omit it for old hosts and stale, wrong-level, defeated or non-Adventure snapshots. Existing 2-2 role context is retained; other chapters still reject the field.

Verification: new host regression failed before implementation; 32 source context tests pass afterward, including 2-2 and shared source context. Hosted pnpm build, pnpm typecheck and pnpm oss:verify pass. Independent focused review found no concrete issue. Game-side evidence is maintained separately in docs/source26-guide-continuity-2026-09-23.md in the PvZ repository.

These checks establish protocol/context behavior, not universal generated dialogue quality or a full-level natural victory.