Add tag probabilities to AI Guard evaluation result

[y9v]

What does this PR do?
This PR adds AIGuard::Evaluation::Result#tag_probabilities attribute, exposing the tag_probs field from the AI Guard API response.

Motivation:
We want to add evaluation result tag probabilities to our SDK, and attach tag probabilities to metastruct.

Change log entry
Yes. AI Guard evaluation results now include tag probabilities from the API response.

Additional Notes:
APPSEC-61897

How to test the change?
CI and manual testing

[github-actions]

Typing analysis

Note: Ignored files are excluded from the next sections.

steep:ignore comments

This PR introduces 1 steep:ignore comment, and clears 1 steep:ignore comment.

steep:ignore comments (+1-1)

❌ Introduced:

lib/datadog/ai_guard/evaluation.rb:66

✅ Cleared:

lib/datadog/ai_guard/evaluation.rb:65

Untyped methods

This PR introduces 1 partially typed method, and clears 1 partially typed method.

Partially typed methods (+1-1)

❌ Introduced:

sig/datadog/ai_guard/evaluation/result.rbs:29
└── def initialize: (::Hash[::String, untyped] raw_response_body) -> void

✅ Cleared:

sig/datadog/ai_guard/evaluation/result.rbs:28
└── def initialize: (::Hash[::String, untyped] raw_response_body) -> void

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

[datadog-datadog-prod-us1]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 94.12%
• Overall Coverage: 95.35% (+0.05%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 672a7c7 | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!}

[pr-commenter]

Benchmarks

Benchmark execution time: 2026-04-13 11:56:19

Comparing candidate commit 672a7c7 in PR branch ai-guard-tag-probabilities with baseline commit b9193de in branch master.

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

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

• 🟩 = significantly better candidate vs. baseline
• 🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

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

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       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 ----------------------------------'