Auto-compression not triggering before context limit — forces conversation restart

Description

Since upgrading to Claude Opus 4.6, the automatic context compression that previously worked reliably no longer triggers before hitting the context limit. Instead of auto-compressing the conversation, it immediately shows:

Context limit reached · /compact or /clear to continue

The problem is that even /compact cannot be typed — the error blocks all input.

Expected behavior

The conversation should auto-compress (as it did before the 4.6 model update) when approaching the context limit, allowing the session to continue seamlessly.

Actual behavior

• No auto-compression happens
• "Context limit reached" error appears abruptly
• /compact is sometimes inaccessible due to the blocked input state
• The only workaround is /clear (losing all context) or restarting the session

Environment

• Claude Code version: 2.1.37
• OS: macOS (Darwin 24.6.0)
• Model: Claude Opus 4.6

Reproduction

1. Start a conversation with multiple file reads and edits (e.g., working on a NestJS + Vue project)
2. Continue the conversation for several tool calls
3. Context limit is hit without auto-compression triggering

Workaround

Breaking work into shorter sessions and starting new conversations frequently.