Claude Code Compaction Loses All Context When Summary API Fails

What this error means

Compaction irreversibly discards context when summary API call fails (401, 429, 500) is a Claude Code failure pattern reported for developers trying to prevent losing entire conversation context when claude code /compact api call fails. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Issue #57636 reports that manual /compact discards original conversation before confirming summary API success. When API returns 401, 429, or 500, context is lost and replaced with raw error message as continuation.

Common causes

• When developers run /compact in long sessions and the summary API returns 401/429/500, the original conversation is irreversibly lost and replaced with the raw error message. This is a data-loss bug unique to Claude Code.
• Issue #57636 reports that manual /compact discards original conversation before confirming summary API success. When API returns 401, 429, or 500, context is lost and replaced with raw error message as continuation.

Quick fixes

1. Confirm the exact error signature matches Compaction irreversibly discards context when summary API call fails (401, 429, 500).
2. Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
3. Verify the account session, API key, provider settings, and environment where the failing tool is running.

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/57636

Evidence note: Issue #57636 reports that manual /compact discards original conversation before confirming summary API success. When API returns 401, 429, or 500, context is lost and replaced with raw error message as continuation.

Related errors

• Claude Code API key expired during long session
• Claude Code context window exceeded with compaction
• Claude Code session restoration after crash

FAQ

What should I check first?

Start with the exact Compaction irreversibly discards context when summary API call fails (401, 429, 500) 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 Compaction irreversibly discards context when summary API call fails (401, 429, 500).