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Third-party model still claims based on GPT-5 - Codex

Quick fix

Move the baseInstructions override out of the if profile != ProxyChat block so it applies to ProxyChat. Currently it is not injected even when set.

Symptom

Section titled “Symptom”
Error output
模型回答中提到 "GPT-5"，而非实际模型名
English translation

The model response mentions "GPT-5" instead of the actual model name

Cause

Section titled “Cause”

The root cause is in `codex_catalog_model_entry()` (L498) in `src-tauri/src/codex_config.rs`: the `baseInstructions` override logic is wrapped in an `if profile != CodexCatalogToolProfile::ProxyChat` condition. `CodexCatalogToolProfile::from_api_format()` (L146-153) classifies every provider whose `apiFormat` is not `"openai_responses"` or `"anthropic"` as ProxyChat. ProxyChat templates come from `models_cache.json`, `codex debug models --bundled`, or the static `gpt5_5_template.json`, and the first sentence of `base_instructions` in these sources is "You are Codex, a coding agent **based on GPT-5**.". As a result, when DeepSeek, Qwen, Moonshot, or similar providers connect to Codex through `openai_chat`, the model reuses the template and introduces itself as GPT-5. Issue #5969 suggests moving the override logic out of that `if` block. At the time of that issue it was still open, with no merged fix or maintainer confirmation visible; this is currently a code-level fix.

Fix

Section titled “Fix”

  1. Confirm that your provider uses `apiFormat: "openai_chat"` (or any format other than `openai_responses` / `anthropic`). Codex then enters the ProxyChat branch.

  2. Edit `src-tauri/src/codex_config.rs` and move the `baseInstructions` override logic outside the `if profile != CodexCatalogToolProfile::ProxyChat` block so it applies to all profiles.

    // src-tauri/src/codex_config.rs
    if let Some(base_instructions) = spec
        .base_instructions
        .as_deref()
        .map(str::trim)
        .filter(|s| !s.is_empty())
    {
        entry_obj.insert("base_instructions".to_string(), json!(base_instructions));
    }
    

    if profile != CodexCatalogToolProfile::ProxyChat {
        // 原有 tools 清理 + supports_parallel_tool_calls 逻辑保持不变
        // ...
    }

  3. Rebuild and run cc-switch, then ask Codex "What model are you based on?" and confirm the answer no longer contains "based on GPT-5".

Affected Versions

Section titled “Affected Versions”
ToolCodex
VersionUnknown
PlatformsUnknown

Source Issues

Section titled “Source Issues”

This page is distilled from 1 real issues

FAQ

Section titled “FAQ”

(No FAQ yet)

Section titled “Related problems”
API Error: 400 Param Incorrect Claude CodeUpgrade CC Switch to v3.16.2+ to fix 400 errors caused by missing reasoning_content in MiMo thinking mode.2 issues mergedNo DEEPSEEK settings in the json config fileUpgrade cc-switch to v3.20.0+, tick the reasoning level in the model mapping and save again, to fix config not being written or overwritten by a template.6 issues merged400 content[].thinking must be passed backUpgrade cc-switch to v3.15.0 or newer to fix lost thinking blocks, or downgrade Claude Code and use the native DeepSeek Anthropic endpoint.4 issues merged

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