fix(agent): reapply provider headers after model switch (#61099) - #61732
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switch_model() rebuilds _client_kwargs from scratch (api_key + base_url) but does not call _apply_client_headers_for_base_url(), so provider- specific headers like OpenRouter HTTP-Referer and X-Title are lost. Subsequent requests show "Unknown" in OpenRouter dashboard logs. Call _apply_client_headers_for_base_url() after rebuilding _client_kwargs and before creating the new client. Fixes #61099
Three tests for the #61099 salvage: OpenRouter attribution headers present after switching to openrouter.ai, Kimi User-Agent sentinel present after switching to api.kimi.com, and stale headers cleared when switching to a provider with no URL-specific headers. 2/3 fail on unpatched main (DID NOT ATTACH), confirming the bug.
alt-glitch
added
type/bug
This was referenced Jul 10, 2026
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Summary
Provider-specific default headers now survive
/modelswitches. Salvages PR #61347 by @AlexFucuson9 (fixes #61099).Root cause:
switch_model()rebuilds_client_kwargsfrom scratch (api_key + base_url + TLS + timeout) but never called_apply_client_headers_for_base_url()— the one client-rebuild site that skipped it (init and credential-swap rebuilds both call it). After any model switch, OpenRouter attribution headers (HTTP-Referer / X-Title) were dropped → logs show "Unknown"; switching TO Kimi mid-session shipped a client without the required User-Agent sentinel → 403s.Changes
agent/agent_runtime_helpers.py: call_apply_client_headers_for_base_url(effective_base)after rebuilding_client_kwargs, before_create_openai_client()(contributor commit, +5).tests/run_agent/test_switch_model_reapplies_headers.py: 3 regression tests — OpenRouter attribution present, Kimi sentinel present, stale headers cleared on switch to an unheadered provider (follow-up commit).Validation
Note: this restores existing header behavior on a missed rebuild path — no new telemetry surface (headers already applied at init and credential swap).
Contributor authorship preserved via cherry-pick; merge with rebase.
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