Context hit 1M token limit with no auto-compaction and no recovery path

Bug description

During a normal coding session, the conversation context grew to the 1M token limit without auto-compaction triggering. When the limit was hit, the error message was about requiring more credits to use 1M context — misleading, since the user never opted into extended context. Manual /compact was also unavailable or broken at that point, leaving the user stranded with no way to continue the session.

Expected behavior

• Auto-compaction should trigger before hitting the 1M limit
• If auto-compaction fails, /compact should still be available as a fallback
• If the limit is hit, the error should offer a recovery path (e.g., "run /compact"), not a billing/credits message

Actual behavior

• Context grew to 1M without auto-compaction firing
• /compact was not usable when needed
• Error message referenced credits/billing for 1M context, which is confusing and unhelpful
• User was forced to start a new conversation, losing session context

Environment

• Claude Code version: 2.1.158
• OS: Linux (WSL2)
• Model: claude-sonnet-4-6

Impact

High — basic session continuity broken, user loses all conversation context mid-task with no recovery option.