Respect caller-provided User-Agent in Api.DownloadBytes#9458
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Martin-Molinero merged 1 commit intoMay 6, 2026
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Skip setting the default "QCAlgorithm.Download(): User Agent Header" when the caller already supplied a User-Agent in the headers dictionary. The check uses HttpRequestHeaders.Contains, which matches header names case-insensitively per the HTTP spec. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
jaredbroad
approved these changes
May 6, 2026
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Description
Api.DownloadBytesalways set a defaultUser-Agentheader ("QCAlgorithm.Download(): User Agent Header") before applying caller-supplied headers. BecauseHttpRequestHeadersdeduplicates case-insensitively butTryAddWithoutValidationdoes not replace an existing header, a caller that passed their ownUser-Agent(in any casing) ended up sending the default value instead of the one they specified.The default is now applied only when the caller has not already supplied a
User-Agent. The check usesDefaultRequestHeaders.Contains("User-Agent"), which matches header names case-insensitively per the HTTP spec, souser-agent,User-Agent, andUSER-AGENTare all detected.Related Issue
N/A — small fix surfaced while reviewing
Api.DownloadBytes.Motivation and Context
Algorithms calling
QCAlgorithm.Download(...)with a customUser-Agent(e.g., to comply with a third-party API's UA policy) were silently overridden by the framework default, causing requests to be rejected or rate-limited by the remote endpoint.Requires Documentation Change
No.
How Has This Been Tested?
HttpRequestHeaders.Containssemantics (case-insensitive header-name match).headersisnullor has no UA, the default UA is added.headerscontains aUser-Agent(any casing), the default is skipped and the caller's value is sent.Types of changes
Checklist:
bug-<issue#>-<description>orfeature-<issue#>-<description>