feat: add process tags to traces

[wantsui]

What does this PR do?

The goal of AIDM-253 is to add process tags to the trace payloads.

I'm creating a draft for now but I still need to research some things like:
[x] add memoization or some kind of cache to avoid looking for these values over and over when are fixed by process
[] figure out the best place to add more tests to assert on the overall behavior (right now I have a test in process_spec to assert on the values)
[x] research if Windows is part of this testing strategy -> Not supported
[x] determine how to approach server type since it's not at the process level -> Will remove in this PR and add later
[x] normalization of tags

After this gets merged, the next step is to add it for the other products.

Main tests:

bundle exec rspec spec/datadog/core/environment/process_spec.rb
bundle exec rspec spec/datadog/tracing/transport/trace_formatter_spec.rb
bundle exec rspec spec/datadog/core/normalizer_spec.rb

Motivation:

Change log entry

Add process tags to trace payloads.

Additional Notes:

How to test the change?

[github-actions]

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^{Visited at: 2025-11-11 18:46:13 UTC}

[datadog-official]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage
• Patch Coverage: 100.00%
• Total Coverage: 98.44% (+0.02%)

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[marcotc]

This convert possible windows separator to unix, correct?

[wantsui]

I don't have a way to test in Windows to confirm this, but also based on the compatibility docs we don't support Windows: https://docs.datadoghq.com/tracing/trace_collection/compatibility/ruby/#supported-operating-systems?

[marcotc]

This is impossible right? If so, we can remove it, as it would give us a false sense of uncertainty here.

[wantsui]

I think I fixed it in 8dae705 by just removing the check in process tags, but let me know if you spot issues with it!

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-11-11 20:54:12

Comparing candidate commit f5ca84a in PR branch add-process-tags-to-tracing with baseline commit 4d6369e in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 44 metrics, 2 unstable metrics.

[wantsui]

@marcotc - do you think there's value in asserting for the values of the tag? Or is the test in process_spec enough?

[github-actions]

Typing analysis

Note: Ignored files are excluded from the next sections.

Untyped methods

This PR introduces 5 untyped methods and 2 partially typed methods. It decreases the percentage of typed methods from 53.12% to 52.89% (-0.23%).

Untyped methods (+5-0)

❌ Introduced:

sig/datadog/core/environment/process.rbs:7
└── def self?.entrypoint_workdir: () -> untyped
sig/datadog/core/environment/process.rbs:9
└── def self?.entrypoint_type: () -> untyped
sig/datadog/core/environment/process.rbs:11
└── def self?.entrypoint_name: () -> untyped
sig/datadog/core/environment/process.rbs:13
└── def self?.entrypoint_basedir: () -> untyped
sig/datadog/core/environment/process.rbs:15
└── def self?.serialized: () -> untyped

Partially typed methods (+2-0)

❌ Introduced:

sig/datadog/core/environment/process.rbs:14
└── def self?.serialized_kv_helper: (untyped key, untyped value) -> ::String
sig/datadog/core/normalizer.rbs:5
└── def self.normalize: (untyped original_value) -> ("" | untyped)

Untyped other declarations

This PR introduces 1 untyped other declaration. It increases the percentage of typed other declarations from 66.92% to 67.05% (+0.13%).

Untyped other declarations (+1-0)

❌ Introduced:

sig/datadog/core/environment/process.rbs:5
└── @serialized: untyped

If you believe a method or an attribute is rightfully untyped or partially typed, you can add # untyped:accept to the end of the line to remove it from the stats.