[AUTO] Add release notes for 3.6.0

[opensearch-ci-bot]

Add release notes for 3.6.0

Borderline Calls

• Add support of IndexWarmer for replica shards with segment replication enabled #20650 (IndexWarmer for replicas): Categorized as Enhancement rather than Feature since index warming already exists; this extends it to replica shards with segment replication.
• [Pull-based Ingestion] Remove experimental tag for pull-based ingestion #20704 (Remove experimental tag for pull-based ingestion): Included as Feature since promoting from experimental to GA is user-facing. Could be argued as Maintenance.
• Make Telemetry Tags Immutable #20788 (Immutable Tags): Categorized as Enhancement. Internal refactoring but changes public API behavior (addTag now returns new instance) and has performance implications.
• Add indexer interface for shard interaction with underlying engines #20675 (Indexer interface): Categorized as Enhancement. Primarily an internal abstraction but introduces a new public interface that plugin authors may interact with.
• Prevent criteria update for context aware indices #20250 (Prevent criteria update): Categorized as Enhancement. Could be considered a Bug Fix depending on perspective, but it's a deliberate behavioral restriction.
• Introducing indexing & deletion strategy planner interfaces #20585 (Strategy planner interfaces): Excluded as internal refactoring with no user-facing behavior change; foundational for future work.
• Disable concurrent search for filter duplicates in significant_text #20857/Revert "Disable concurrent search for filter duplicates" #20915 (Disable/revert concurrent search for significant_text): Excluded as the commit and revert cancel each other out.
• feat(hunspell): Add ref_path support for package-based dictionary loa… #20840 (Hunspell ref_path): Categorized as Enhancement. Could be Feature since it adds a new parameter, but it extends existing Hunspell functionality.
• Move Randomness from server to lib/common #20570 (Move Randomness): Categorized as Bug Fix since it fixes FIPS installer size issue, though it's partly maintenance.
• Harden detection of HTTP/3 support by ensuring Quic native libraries are available for the target platform #20680 (Harden HTTP/3 detection): Categorized as Bug Fix since it prevents crashes on unsupported platforms.
• Use env variable (OPENSEARCH_FIPS_MODE) to enable opensearch to run in FIPS enforced mode instead of checking for existence of bcFIPS jars #20625 (FIPS env variable): Categorized as Bug Fix since the previous behavior would incorrectly enforce FIPS mode when bcFIPS jars are present in default builds.
• Ensure that transient ThreadContext headers with propagators survive restore #20854 (ThreadContext headers): Included as Bug Fix despite skip-diff-analyzer label since it fixes a real tracing/context propagation bug.
• Fix stream transport TLS cert hot-reload by using live SSLContext fro… #20734 (Stream transport TLS hot-reload): Excluded due to skip-diff-analyzer label and being an internal transport fix closely related to Flight transport TLS cert hot-reload #20700 (Flight TLS hot-reload) which was also excluded as a backport-targeted fix.
• Flight transport TLS cert hot-reload #20700 (Flight transport TLS cert hot-reload): Excluded as it's marked backport 3.5, suggesting it's a fix being backported rather than new 3.6.0 work.
• Adding stream request flag to SearchRequestContext #20530 (Stream request flag): Included despite backport 3.5 label since it adds new functionality to SearchRequestContext.
• [GRPC] Add accessUnixDomainSocket permission for transport-grpc #20463 (GRPC Unix domain socket permission): Excluded as CI/test infrastructure fix.
• [GRPC] Handle ShardSearchFailure properly #20641 (GRPC ShardSearchFailure): Excluded as internal proto fix with no user-facing config/behavior change.
• [AUTOCUT] Gradle Check Flaky Test Report for OpenSearchTestBasePluginFuncTest #20955 (Flaky test fix): Excluded as test-only change.
• Remove incorrect entries re-added by 3154811 #20853 (Remove incorrect changelog entries): Excluded as release machinery.
• [AUTO] [main] Add bwc version 2.19.6. #20274 (Add bwc version): Excluded as release machinery.
• [Backport 3.6] Updated MMapDirectory to use ReadAdviseByContext rather than default readadvise of Lucene #21062 (MMapDirectory ReadAdviseByContext): Included as Bug Fix/performance improvement since it affects read behavior.

[github-actions]

PR Reviewer Guide 🔍

(Review updated until commit 4d0319b)

Here are some key observations to aid the review process:

🧪 No relevant tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ Recommended focus areas for review Misplaced Entry Line 24 (Fix ProfileScorer.getChildren() to expose wrapped scorer in the scorer tree hierarchy) is categorized under Enhancements but starts with "Fix", which typically indicates a Bug Fix. This entry may be miscategorized. * Fix `ProfileScorer.getChildren()` to expose wrapped scorer in the scorer tree hierarchy ([#20607](https://github.com/opensearch-project/OpenSearch/pull/20607)) Misplaced Entry Line 37 (Expose STRICT_EXPAND_OPEN_HIDDEN_FORBID_CLOSED index option via static method) is listed under Bug Fixes, but exposing an index option via a static method sounds more like an Enhancement or API change rather than a bug fix. * Expose `STRICT_EXPAND_OPEN_HIDDEN_FORBID_CLOSED` index option via static method ([#20980](https://github.com/opensearch-project/OpenSearch/pull/20980)) Future Date The release notes are dated for version 3.6.0, but today's date is 2026-04-02. If this version has not yet been released, ensure all referenced PRs are actually merged and included in 3.6.0, and that no PRs from future milestones are accidentally included. ## Version 3.6.0 Release Notes Compatible with OpenSearch and OpenSearch Dashboards version 3.6.0

[github-actions]

PR Code Suggestions ✨

Latest suggestions up to c769465

Explore these optional code suggestions:

Category	Suggestion	Impact
General	Misclassified fix entry in wrong section This entry is listed under "Enhancements" but describes a fix (Fix ...). Items prefixed with "Fix" are conventionally placed under "Bug Fixes". Consider moving this entry to the "Bug Fixes" section for consistency. release-notes/opensearch.release-notes-3.6.0.md [27] +Move to Bug Fixes section: * Fix `ProfileScorer.getChildren()` to expose wrapped scorer in the scorer tree ([#20607](https://github.com/opensearch-project/OpenSearch/pull/20607)) Suggestion importance[1-10]: 5 __ Why: The entry Fix ProfileScorer.getChildren() is prefixed with "Fix" and describes a bug fix, yet it's placed under "Enhancements". Moving it to "Bug Fixes" would improve consistency and accuracy of the release notes categorization.	Low
	Entries misclassified under Maintenance section These two entries are listed under "Maintenance" but describe feature additions and bug fixes rather than dependency bumps or infrastructure maintenance. "Add Arrow Flight TLS certificate hot-reload support" belongs in "Features" or "Enhancements", and "Handle ShardSearchFailure properly in gRPC transport" belongs in "Bug Fixes". release-notes/opensearch.release-notes-3.6.0.md [89-90] +Move to appropriate sections: + +Under Enhancements: * Add Arrow Flight TLS certificate hot-reload support ([#20700](https://github.com/opensearch-project/OpenSearch/pull/20700)) + +Under Bug Fixes: * Handle `ShardSearchFailure` properly in gRPC transport ([#20641](https://github.com/opensearch-project/OpenSearch/pull/20641)) Suggestion importance[1-10]: 5 __ Why: The entries "Add Arrow Flight TLS certificate hot-reload support" and "Handle ShardSearchFailure properly in gRPC transport" describe a feature/enhancement and a bug fix respectively, but are placed under "Maintenance" which typically covers dependency bumps and infrastructure changes. Recategorizing them would improve release notes accuracy.	Low

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Previous suggestions

Suggestions up to commit a67ce85

Category	Suggestion	Impact
General	Misclassified bug fix under Features section This entry is listed under "Features" but its title starts with "Fix/", which strongly suggests it is a bug fix rather than a new feature. It should be moved to the "Bug Fixes" section to accurately categorize the change. release-notes/opensearch.release-notes-3.6.0.md [11] -* Fix/collision of indexpatterns ([#20702](https://github.com/opensearch-project/OpenSearch/pull/20702)) +(move to Bug Fixes section) +* Fix collision of indexpatterns ([#20702](https://github.com/opensearch-project/OpenSearch/pull/20702)) Suggestion importance[1-10]: 4 __ Why: The entry Fix/collision of indexpatterns does appear to be a bug fix based on its title prefix, and placing it under "Features" is potentially misleading. However, the PR author may have intentionally categorized it this way based on the actual nature of the change, so this is a moderate concern.	Low
	Misclassified bug fix under Enhancements section This entry is listed under "Enhancements" but its title starts with "Fix", indicating it is a bug fix. It should be moved to the "Bug Fixes" section for accurate categorization. release-notes/opensearch.release-notes-3.6.0.md [18] +(move to Bug Fixes section) * Fix ProfileScorer.getChildren() to expose wrapped scorer in scorer tree ([#20607](https://github.com/opensearch-project/OpenSearch/pull/20607)) Suggestion importance[1-10]: 4 __ Why: The entry Fix ProfileScorer.getChildren() starts with "Fix" suggesting it's a bug fix rather than an enhancement. Moving it to "Bug Fixes" would improve accuracy of the release notes categorization.	Low
	Add missing newline at end of file The file is missing a newline at the end, as indicated by the "No newline at end of file" warning. Most style guides and tools require files to end with a newline character to avoid issues with concatenation and diffs. release-notes/opensearch.release-notes-3.6.0.md [113] +* Prevent criteria update for context aware indices ([#20250](https://github.com/opensearch-project/OpenSearch/pull/20250)) - Suggestion importance[1-10]: 2 __ Why: The existing_code and improved_code are identical, meaning no actual change is demonstrated. While adding a trailing newline is a minor best practice, the suggestion fails to show the improvement concretely.	Low

Suggestions up to commit 28f6c9f

Category	Suggestion	Impact
General	Bug fixes misplaced in enhancements section These two entries start with "Fix" which typically indicates bug fixes, but they are listed under "Enhancements". They should be moved to the "Bug Fixes" section to maintain consistency and accuracy in the release notes. release-notes/opensearch.release-notes-3.6.0.md [18-19] +Move to ### Bug Fixes: * Fix ProfileScorer.getChildren() to expose wrapped scorer in scorer tree ([#20607](https://github.com/opensearch-project/OpenSearch/pull/20607)) * Fix terms lookup subquery to use cluster max_clause_count setting ([#20823](https://github.com/opensearch-project/OpenSearch/pull/20823)) Suggestion importance[1-10]: 4 __ Why: The entries starting with "Fix" under ### Enhancements do appear misplaced, as they would more naturally belong in ### Bug Fixes. This is a valid categorization concern that improves release note accuracy.	Low
	Entry placed in undefined section The "Unknown" section is not a standard release notes category and should be avoided. This entry about IndexWarmer support appears to be a feature or enhancement and should be moved to the appropriate section. release-notes/opensearch.release-notes-3.6.0.md [97] +Move to ### Features or ### Enhancements: * Add support of IndexWarmer for replica shards with segment replication enabled ([#20650](https://github.com/opensearch-project/OpenSearch/pull/20650)) Suggestion importance[1-10]: 4 __ Why: The ### Unknown section is non-standard and the entry about IndexWarmer support clearly belongs in ### Features or ### Enhancements. This is a valid improvement to release note quality.	Low
	Misclassified entry in wrong section This entry appears to be an API/infrastructure change rather than a bug fix, as exposing a static method is typically a feature or enhancement. Consider moving it to the "Features" or "Enhancements" section for accurate categorization. release-notes/opensearch.release-notes-3.6.0.md [26] +Move to ### Enhancements: * Add static method to expose STRICT_EXPAND_OPEN_HIDDEN_FORBID_CLOSED index option ([#20980](https://github.com/opensearch-project/OpenSearch/pull/20980)) Suggestion importance[1-10]: 3 __ Why: The suggestion raises a valid point about categorization, but "Add static method to expose STRICT_EXPAND_OPEN_HIDDEN_FORBID_CLOSED index option" could legitimately be a bug fix (exposing a missing method to fix broken functionality). The categorization is debatable and the impact is low.	Low

[github-actions]

Persistent review updated to latest commit a67ce85

[github-actions]

Persistent review updated to latest commit f60e73e

[andrross]

This is a much better version. Another fix is in flight to get the "borderline calls" details in the PR body: opensearch-project/opensearch-build#6076

[github-actions]

Persistent review updated to latest commit a2968b7

[github-actions]

Persistent review updated to latest commit 19ca092

[github-actions]

PR Code Analyzer ❗

AI-powered 'Code-Diff-Analyzer' found issues on commit c769465.

Path	Line	Severity	Description
release-notes/opensearch.release-notes-3.6.0.md	72	high	Dependency version change: Apache Lucene bumped from 10.3.2 to 10.4.0. Maintainers must verify artifact authenticity.
release-notes/opensearch.release-notes-3.6.0.md	73	high	Dependency version change: OpenTelemetry bumped to 1.60.1 and OpenTelemetry Semconv to 1.40.0. Maintainers must verify artifact authenticity.
release-notes/opensearch.release-notes-3.6.0.md	74	high	Dependency version change: Project Reactor bumped to 3.8.4 and Reactor Netty to 1.3.4. Maintainers must verify artifact authenticity.
release-notes/opensearch.release-notes-3.6.0.md	75	high	Dependency version change: Netty bumped to 4.2.12.Final. Maintainers must verify artifact authenticity.
release-notes/opensearch.release-notes-3.6.0.md	76	high	Dependency version change: Jackson updated to 2.21.2. Maintainers must verify artifact authenticity.
release-notes/opensearch.release-notes-3.6.0.md	77	high	Dependency version change: logback-classic bumped to 1.5.32 and logback-core to 1.5.27. Maintainers must verify artifact authenticity.
release-notes/opensearch.release-notes-3.6.0.md	78	high	Dependency version change: nimbus-jose-jwt bumped from 10.7 to 10.8. This library handles JWT/crypto operations; maintainers must verify artifact authenticity.
release-notes/opensearch.release-notes-3.6.0.md	82	high	Dependency version change: shadow-gradle-plugin bumped from 8.3.9 to 9.3.1 (major version bump). Build plugins execute during the build pipeline; maintainers must verify artifact authenticity.
release-notes/opensearch.release-notes-3.6.0.md	83	high	Dependency version change: GitHub Action tj-actions/changed-files bumped from 47.0.1 to 47.0.5. CI/CD actions run with repository permissions; maintainers must verify the pinned commit SHA.
release-notes/opensearch.release-notes-3.6.0.md	84	high	Dependency version change: aws-actions/configure-aws-credentials bumped from 5 to 6 (major version bump). This action handles AWS credentials in CI/CD; maintainers must verify the pinned commit SHA.

The table above displays the top 10 most important findings.

Total: 20 | Critical: 0 | High: 20 | Medium: 0 | Low: 0

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[github-actions]

Persistent review updated to latest commit c769465

[github-actions]

Persistent review updated to latest commit 4d0319b