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Context window errors and /compact will not run - Claude Code / Codex

Quick fix

Set the correct model_context_window for the model by hand in cc-switch, so a wrong default does not break compaction or cause a 422.

Symptom

Section titled “Symptom”
Error output
实际上下文窗口在117.9k就出现了报错且无法/compact
English translation

The actual context window errors at 117.9k and /compact will not run

Cause

Section titled “Cause”

When switching model or generating a model catalogue, cc-switch falls back to a wrong default context window size (1M or 128000) if none is specified explicitly. Claude Code or Codex then cannot calculate the remaining context correctly, so automatic compaction (/compact) fails, it reports full early, or it sends an oversized context upstream and triggers a 422.

The related issues are all still open, so there is no automatic context window sync fix yet — you have to override the default in the config by hand.

Fix

Section titled “Fix”

  1. In the cc-switch model config, set the correct model_context_window explicitly for the model you use (272000 for GPT-5.6, for example) to override the wrong fallback default.

    // cc-switch-model-catalog.json
    {
      "models": [
        {
          "id": "gpt-5.6-sol",
          "model_context_window": 272000
        }
      ]
    }

Affected Versions

Section titled “Affected Versions”
ToolClaude Code, Codex
Version3.16.3 - 3.18.0
PlatformsWindowsmacOS

Source Issues

Section titled “Source Issues”

This page is distilled from 5 real issues

FAQ

Section titled “FAQ”
Why does the context still show 1M after switching model?
A known cc-switch problem: the context window config is not updated automatically after a model switch, so it still calculates against 1M. Set the correct size by hand.
Do all models support automatic compaction?
Not all of them. But if the context window is configured correctly and the model itself supports it, compaction should work — a wrong config breaks it outright.
Section titled “Related problems”
Only a 200K context window shows in actual use - Claude CodeChange the default model in `~/.claude/settings.json` to the `[1m]` variant, or run `/model claude-opus-4-8[1m]` in the session, to activate the 1M context.5 issues merged"is not a model this version of Claude Code recognizes" - CC SwitchSet CLAUDE_CODE_MAX_CONTEXT_TOKENS or append [1m] to the model name to define the correct context window size.3 issues mergedconfig.toml and auth.json still hold the previous third-party APIUpgrade CC Switch to v3.16.1+, restart, and switch Codex provider again. If official OAuth broke, run codex logout then codex login --device-auth.11 issues merged

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