feat(openfeature): add feature flag configuration settings

[pavlokhrebto]

What does this PR do?

Adds stable OpenFeature settings for Feature Flags enablement, configuration source selection, and agentless delivery timeouts. Implements cross-SDK precedence and validation while preserving the deprecated DD_EXPERIMENTAL_FLAGGING_PROVIDER_ENABLED behavior for existing adopters.

Motivation:

Establishes the shared configuration contract required for agentless Feature Flags delivery without moving existing adopters away from Remote Configuration.

Change log entry

Yes. Adds configuration options for selecting and tuning Feature Flags configuration delivery.

Additional Notes:

This is the first PR in a four-PR stack and contains the configuration groundwork. Agentless HTTP delivery and provider lifecycle wiring will follow in subsequent PRs.

How to test the change?

docker compose run --no-deps --rm tracer-4.0 bundle exec rake local_config_map:generate
docker compose run --no-deps --rm -e STANDARDOPTS="lib/datadog/open_feature/configuration.rb spec/datadog/open_feature/configuration/settings_spec.rb" tracer-4.0 bundle exec rake standard
docker compose run --no-deps --rm tracer-4.0 bundle exec rake "steep:check[lib/datadog/open_feature/configuration.rb,spec/datadog/open_feature/configuration]"
docker compose run --no-deps --rm tracer-4.0 bundle exec rake rbs:missing rbs:stale
docker compose run --no-deps --rm tracer-3.1 bundle exec rake test:open_feature
docker compose run --no-deps --rm tracer-4.0 bundle exec rake test:open_feature

[linear-code]

FFLSDK-10

[dd-octo-sts]

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**Change log entry**

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^{Visited at: 2026-08-28 15:37:55 UTC}

[chatgpt-codex-connector]

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[datadog-official]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 99.59%
• Overall Coverage: 90.33% (+0.01%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: d12180d | Docs | View more details | Give us feedback!}

[pavlokhrebto]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: d12180d552

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• Mark a draft as ready
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[chatgpt-codex-connector]

Start an agentless component for the default source

With the documented defaults (DD_FEATURE_FLAGS_ENABLED=true and source agentless), this guard still returns without building an evaluation engine, so adopting Datadog::OpenFeature::Provider produces only fatal/default evaluations. Fresh evidence after the prior review is that Component.build now explicitly accepts only remote_config, while a repo-wide search finds no runtime consumer for the new agentless URL, polling, or request-timeout settings; either wire an agentless component here or avoid exposing it as the working default.

AGENTS.md reference: lib/datadog/open_feature/AGENTS.md:L180-L180

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[chatgpt-codex-connector]

Apply the initialization timeout during provider startup

When a user changes DD_EXPERIMENTAL_FLAGGING_PROVIDER_INITIALIZATION_TIMEOUT_MS, the value cannot affect initialization: the only production reference is this option declaration, Component never reads it, and Provider#init remains a no-op. Consequently the newly documented promise to wait this long for the first configuration is silently ignored for every source.

AGENTS.md reference: lib/datadog/open_feature/AGENTS.md:L180-L180

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