Claude Code Shows Wrong Context Window for Claude Sonnet 4.6 — Registry Stale Bug

What this error means

Claude Code /context reports 200K context for claude-sonnet-4-6 instead of 1M (registry-stale bug) is a Claude Code failure pattern reported for developers trying to fix claude code /context command showing 200k instead of 1m context window for claude-sonnet-4-6. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

anthropics/claude-code issue #58710: Claude Code v2.1.140 shows /context reporting 200K for claude-sonnet-4-6 instead of expected 1M. Same registry-stale bug previously fixed for Opus 4.7. Affects Windows native build.

Common causes

• Claude Code users paying for Max plan expect 1M context with Sonnet 4.6 (per changelog 2.1.49), but /context shows only 200K. This is a registry-stale bug previously fixed for Opus 4.7 in v2.1.117 but not for Sonnet 4.6.
• anthropics/claude-code issue #58710: Claude Code v2.1.140 shows /context reporting 200K for claude-sonnet-4-6 instead of expected 1M. Same registry-stale bug previously fixed for Opus 4.7. Affects Windows native build.

Quick fixes

1. Confirm the exact error signature matches Claude Code /context reports 200K context for claude-sonnet-4-6 instead of 1M (registry-stale bug).
2. Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/anthropics/claude-code/issues/58710

Evidence note: anthropics/claude-code issue #58710: Claude Code v2.1.140 shows /context reporting 200K for claude-sonnet-4-6 instead of expected 1M. Same registry-stale bug previously fixed for Opus 4.7. Affects Windows native build.

Related errors

• Claude Code wrong model context window
• Claude Code model registry not updating

FAQ

What should I check first?

Start with the exact Claude Code /context reports 200K context for claude-sonnet-4-6 instead of 1M (registry-stale bug) text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Claude Code workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without Claude Code /context reports 200K context for claude-sonnet-4-6 instead of 1M (registry-stale bug).