suggestion (non-blocking): make the byte unit visible in the warning and docstring

The bytesize fix is exactly the right call, and the tests are well-chosen — 'é' * 300 at bytesize 600 / size 300, and 'é' * 252 plus prefix at bytesize 514 / size 262. Both straddle 512 such that the new check rejects them and the old .size check would have accepted them, so the tests actively demonstrate the bug being fixed, not just exercise the new path.

A small observation while reading tags_too_large? — at lib/datadog/tracing/distributed/datadog.rb:192 the warning reports size:#{size} >= limit:#{...} with no unit, and the setting docstring at lib/datadog/tracing/configuration/settings.rb:515 ("Maximum size for the x-datadog-tags...") also doesn't say "bytes". A customer setting DD_TRACE_X_DATADOG_TAGS_MAX_LENGTH=512 could keep reasoning in characters even after this lands.

The warning could name the unit:

::Datadog.logger.warn(
  "Failed to #{scenario} x-datadog-tags: tags are too large for configured byte-size limit (size:#{size} >= " \
    "limit:#{::Datadog.configuration.tracing.x_datadog_tags_max_length}). This limit can be configured " \
    'through the DD_TRACE_X_DATADOG_TAGS_MAX_LENGTH environment variable.'
)

Existing /size:600/ and /size:514/ regex assertions still match. The docstring at settings.rb:515 ("Maximum byte size for...") closes the loop end-to-end.

The core fix is correct as-is.

Benchmarks

Benchmark execution time: 2026-05-06 21:44:26

Comparing candidate commit 296b5af in PR branch x-datadog-tags with baseline commit afff006 in branch fix-tracestate.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 45 metrics, 1 unstable metrics.

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

"Maximum size for the x-datadog-tags...") also doesn't say "bytes". A customer setting DD_TRACE_X_DATADOG_TAGS_MAX_LENGTH=512 could keep reasoning in characters even after this lands.

@p-datadog I added the wording around "byte" to the message. Thank you!

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 97.24% (+0.05%)