Claude Code silently escalates to 1M context model and bills usage credits without user consent, bypassing auto-compaction

Bug Report

What happened

During a session where the conversation context grew large, Claude Code automatically switched to the 1M context model and billed usage credits — without any confirmation prompt or warning to the user. The auto-compaction feature (which should compact the conversation and stay on standard context) did not fire before this escalation occurred.

Expected behavior

1. Auto-compaction should trigger before any model escalation
2. If a model switch would incur usage credit charges, the user should be explicitly asked for consent before proceeding

Actual behavior

• Auto-compaction did not run
• Claude Code silently escalated to the 1M context model
• Usage credits were billed without user awareness or consent
• User only discovered this after credits were depleted

Impact

User lost usage credits without knowledge or consent.