Opus 4.8: false '1M context credits required' on standard-context session after /clear

Preflight Checklist

• [x] I have searched existing issues and found related but not identical reports (#61692, #64534)
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

Opus 4.6 (and 4.8) immediately throws "Usage credits required for 1M context" on a fresh session — including right after /clear. The session is NOT using 1M context explicitly. The model was selected via the standard model picker, not the [1m] variant.

Additionally, enabling usage credits at claude.ai/settings/usage (with $0 limit, as suggested by community workarounds in #61692) does NOT resolve the issue. The error persists even after enabling credits and returning to the session.

Error Message

API Error: Usage credits required for 1M context · run /usage-credits to turn them on, or /model to switch to standard context

Steps to Reproduce

1. Start Claude Code (CLI or desktop)
2. Select Opus 4.6 or 4.8 via /model
3. Run /clear to start fresh
4. Run any skill/command that triggers an LLM call (e.g. a plugin skill)
5. Error thrown immediately

Expected Behavior

Opus 4.6/4.8 should work on standard 200K context without requiring usage credits. If credits ARE required for 1M, the model picker should offer a non-1M variant, and enabling credits with $0 limit should satisfy the gate.

Actual Behavior

1. All Opus requests are force-routed to 1M context tier
2. The 1M credit gate blocks the request
3. Enabling usage credits (with $0 limit) does NOT unblock it — the error persists in the current session
4. No session restart hint is given

Workaround

None confirmed for Opus. CLAUDE_CODE_DISABLE_1M_CONTEXT=1 may work but defeats the purpose of using Opus with extended context.

Relationship to existing issues

• #61692: Same root cause (false 1M credit gate) but that issue focuses on Sonnet 4.6. This confirms Opus 4.6/4.8 is also affected.
• #64534: Same error in dispatch/background agents. This confirms it also happens in interactive sessions.

Claude Code Version

2.1.160

Platform

macOS (Darwin 25.5.0)

Claude Model

Opus 4.6 / Opus 4.8

Is this a regression?

Yes — worked in earlier CC versions without requiring usage credits for standard Opus sessions.