Python: case-insensitive User-Agent detection prevents duplicate headers - #8521
Open
Manohar Paturi (ManoharPaturi) wants to merge 1 commit into
Open
Manohar Paturi (ManoharPaturi) wants to merge 1 commit into
Manohar Paturi (ManoharPaturi) wants to merge 1 commit into
Conversation
prepend_agent_framework_to_user_agent looked up the exact key
"User-Agent" when deciding whether an incoming headers dict already
carries a user agent. HTTP header names are case-insensitive, so a caller
passing default_headers={"user-agent": "my-app/1.0"} (for example to
OpenAI clients or the A2A agent) ended up with two User-Agent entries:
their original one plus a new agent-framework one. httpx then sends both
header lines, and which value a server honors is undefined.
Find the existing entry case-insensitively and prepend to it in place, so
exactly one User-Agent header survives.
Manohar Paturi (ManoharPaturi)
deployed
to
github-app-auth
September 18, 2026 12:29 — with 
GitHub Actions
Active
GitHub Actions
Active
Manohar Paturi (ManoharPaturi)
deployed
to
github-app-auth
September 18, 2026 12:29 — with
GitHub Actions
Active
GitHub Actions
Active
Manohar Paturi (ManoharPaturi)
deployed
to
github-app-auth
September 18, 2026 12:29 — with
GitHub Actions
Active
GitHub Actions
Active
agent-framework-automation
Bot
added
the
python
Manohar Paturi (ManoharPaturi)
deployed
to
github-app-auth
September 18, 2026 12:29 — with
GitHub Actions
Active
GitHub Actions
Active
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Motivation & Context
Fixes #8520. exact-case "User-Agent" detection let a lowercase user-agent through, producing duplicate UA header lines.
Description & Review Guide
Related Issue
Fixes #8520
Contribution Checklist