[OpenTelemetry] Add AlwaysRecordSampler

[martincostello]

Changes

Add AlwaysRecordSampler, which is now stable (open-telemetry/opentelemetry-specification#4934), based on original proposal in #6732.

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

❌ Patch coverage is 91.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 91.72%. Comparing base (e7c3757) to head (891e4e9).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...OpenTelemetry/Trace/Sampler/AlwaysRecordSampler.cs	91.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7695      +/-   ##
==========================================
- Coverage   91.76%   91.72%   -0.04%     
==========================================
  Files         336      337       +1     
  Lines       18302    18314      +12     
==========================================
+ Hits        16794    16798       +4     
- Misses       1508     1516       +8     

Flag	Coverage Δ
unittests-Project-Experimental	91.77% <91.66%> (-0.10%)	⬇️
unittests-Project-Stable	91.80% <91.66%> (-0.05%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...OpenTelemetry/Trace/Sampler/AlwaysRecordSampler.cs	91.66% <91.66%> (ø)

... and 4 files with indirect coverage changes

[Copilot]

Pull request overview

Adds the stable AlwaysRecordSampler decorator to the tracing SDK.

Changes:

• Converts Drop decisions to RecordOnly while preserving other results.
• Adds unit tests, public API declarations, and a changelog entry.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/OpenTelemetry/Trace/Sampler/AlwaysRecordSampler.cs	Implements the sampler decorator.
test/OpenTelemetry.Tests/Trace/AlwaysRecordSamplerTests.cs	Tests construction and all decision mappings.
src/OpenTelemetry/.publicApi/Stable/PublicAPI.Unshipped.txt	Registers the stable public API.
src/OpenTelemetry/CHANGELOG.md	Documents the new sampler.

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[opentelemetry-pr-dashboard]

Pull request dashboard status

Merged · refreshed 2026-09-10 17:04 UTC

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[stevejgordon]

General comment. Should we add this to the samplers list in the docs too?

[Kielek]

LGTM