[Liis17]

Summary

Fixes four defects in the regular-chat timeline, catch-up flow, and draft state on Android:

• Confirmed messages now sort chronologically by sentAt with nanosecond precision instead of being appended in sender order, eliminating out-of-order rows.
• After returning to an active chat, missed messages are always fetched from the server, not an incomplete tail from cache; capped at 10 pages of 30 messages per miss, with remaining history loaded on scroll-down.
• A server-revised sent draft no longer loses its tombstone after restart; the client re-reads the server draft and overwrites local state only when the local draft is matching, blank, or strictly newer.
• Chat list display cache (title/avatar/other-user id) is now populated on initial load and saveDisplay() is actually invoked, eliminating redundant per-chat user() lookups on every list refresh.

Testing

• Full testNightlyDebugUnitTest suite passed (exit 0); new tests added for chronological insertion, catch-up page cap, draft tombstone, and cached display resolution.
• Diff covers 11 files (~950 insertions, ~113 deletions) across ChatViewModel, ChatsViewModel, ChatCacheRepository, RegularChatSession, ChatDraftRepository, SearchChatsGateway, and 4 new test files.
• Device runtime checks on Pixel required to confirm realtime catch-up and display cache behaviour; run after the device is authorized (see remaining risks).
• Docs in Obsidian/ClaudeVault/Clients/Android.md updated to document timeline order, catch-up, draft conflicts, and chat display cache.
• Remaining risks: stale avatar from cache after peer deletion; incomplete tail cache defect left in normal scroll-down only.