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[BUG] Custom provider headers (User-Agent) from opencode.json not applied to fetch requests #22608
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Description
Description
When configuring custom headers for a provider in opencode.json, the User-Agent header (and potentially other custom headers) is not actually sent with the API requests.
This is particularly important for providers like Kimi (https://api.kimi.com/coding/v1), where sending a custom User-Agent unlocks higher rate limits and additional coding plan quotas.
Configuration Example
{
"provider": {
"kimi-cli": {
"npm": "@ai-sdk/openai-compatible",
"name": "kimi-cli",
"options": {
"baseURL": "https://api.kimi.com/coding/v1",
"apiKey": "{env:ANTHROPIC_API_KEY}",
"headers": {
"Authorization": "Bearer sk-kimi-xxx",
"User-Agent": "KimiCLI/1.30.0"
}
}
}
}
}Expected Behavior
The User-Agent: KimiCLI/1.30.0 header should be included in the HTTP requests sent to the provider API.
Actual Behavior
The custom User-Agent header is not applied to the outgoing fetch requests. This causes the provider to treat the request as a generic client, missing out on official client benefits (e.g., higher rate limits, extra coding plan quota for Kimi).
Related Issues
- provider headers from config not applied to fetch requests #11789 reported a similar bug with provider headers not being applied to fetch requests, which was supposedly fixed in PR fix(provider): apply config headers to fetch requests #11978. This appears to be a regression or the fix did not cover all cases.
- Are custom provider headers from config expected to work in v1.2.x? #15306 also discusses custom provider headers not working in v1.2.x.
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github-actions commentedon Apr 15, 2026
This issue might be a duplicate of existing issues. Please check:
User-Agent) not reaching the actual HTTP request layer.woaye168 commentedon Apr 15, 2026
Thanks for the triage, but I believe this issue is distinct from #15306 in a few important ways:
Specific symptom: Are custom provider headers from config expected to work in v1.2.x? #15306 is a broad question about whether any custom provider headers work. This issue is specifically about the
User-Agentheader being silently dropped, which is a concrete, reproducible bug.Real-world business impact: For the Kimi provider (
api.kimi.com/coding/v1), theUser-Agentheader is not cosmetic — it directly determines:User-Agent(KimiCLI/1.30.0) are routed to a lower-priority tier.Regression context: provider headers from config not applied to fetch requests #11789 reported the exact same bug and was closed as "fixed" by PR fix(provider): apply config headers to fetch requests #11978. The fact that
User-Agentis still not being forwarded today suggests the previous fix was either incomplete or regressed. This issue highlights a specific header that the prior fix missed.Could a maintainer please confirm whether the custom
fetchwrapper inprovider.tsis stripping/overwriting theUser-Agentheader? Happy to provide packet captures or verbose logs if needed.github-actions commentedon Jul 4, 2026
To stay organized issues are automatically closed after 60 days of no activity. If the issue is still relevant please open a new one.