Forward port release notes for v8.18.2 (#128628)

* Forward port release notes for v8.18.2

* Revert highlights.asciidoc changes

* Revert reversion to highlights.asciidoc

I wasn't awake

---------

Co-authored-by: Liam Thompson <[email protected]>

Author: elasticsearchmachine

docs/reference/migration/migrate_8_18.asciidoc

@@ -81,6 +81,20 @@ Before this change, in case of shard failures, EQL queries always returned an er
 EQL queries that would previously fail due to shard failures, will now succeed and return partial results. The previous defaults can be restored by setting `xpack.eql.default_allow_partial_results` cluster setting to `false` or setting with `allow_partial_search_results` to `false` in the query request.
 ====
 
+[discrete]
+[[breaking_818_esql_changes]]
+==== ES|QL changes
+
+[[limit_scope_skip_unavailable_setting_remote_clusters]]
+.Limit the scope of the skip_unavailable setting for remote clusters
+[%collapsible]
+====
+*Details* +
+Before this change, ES|QL would honor the skip_unavailable setting for nonmatching indices errors at planning time, meaning that when a query with a concrete (non-wildcarded) index was issued to a cluster where skip_unavailable=true, the index would be skipped, allowing the query to proceed on any other specified clusters rather than returning an error.
+
+*Impact* +
+Remote clusters, regardless of their skip_unavailable setting, will now use the same logic as the local cluster for index expression analysis at plan time. As a result, any missing concrete index in your index expression will return an error rather than partial results.
+====
 
 [discrete]
 [[deprecated-8.18]]

docs/reference/release-notes.asciidoc

@@ -7,6 +7,7 @@
 This section summarizes the changes in each release.
 
 * <<release-notes-8.19.0>>
+* <<release-notes-8.18.2>>
 * <<release-notes-8.18.1>>
 * <<release-notes-8.18.0>>
 * <<release-notes-8.17.6>>
@@ -93,6 +94,7 @@ This section summarizes the changes in each release.
 --
 
 include::release-notes/8.19.0.asciidoc[]
+include::release-notes/8.18.2.asciidoc[]
 include::release-notes/8.18.1.asciidoc[]
 include::release-notes/8.18.0.asciidoc[]
 include::release-notes/8.17.6.asciidoc[]

docs/reference/release-notes/8.18.2.asciidoc

@@ -0,0 +1,67 @@
+[[release-notes-8.18.2]]
+== {es} version 8.18.2
+
+Also see <<breaking-changes-8.18,Breaking changes in 8.18>>.
+
+[[breaking-8.18.2]]
+[float]
+=== Breaking changes
+
+Snapshot/Restore::
+* Make S3 custom query parameter optional {es-pull}128043[#128043]
+
+[[bug-8.18.2]]
+[float]
+=== Bug fixes
+
+Aggregations::
+* Fix a bug in `significant_terms` {es-pull}127975[#127975]
+
+Audit::
+* Handle streaming request body in audit log {es-pull}127798[#127798]
+
+Data streams::
+* Fix system data streams incorrectly showing up in the list of template validation problems {es-pull}128161[#128161]
+
+Downsampling::
+* Downsampling does not consider passthrough fields as dimensions {es-pull}127752[#127752] (issue: {es-issue}125156[#125156])
+
+ES|QL::
+* Ensure ordinal builder emit ordinal blocks {es-pull}127949[#127949]
+* Fix union types in CCS {es-pull}128111[#128111]
+
+Infra/Core::
+* Add missing `outbound_network` entitlement to x-pack-core {es-pull}126992[#126992] (issue: {es-issue}127003[#127003])
+* Check hidden frames in entitlements {es-pull}127877[#127877]
+
+Infra/Scripting::
+* Avoid nested docs in painless execute api {es-pull}127991[#127991] (issue: {es-issue}41004[#41004])
+
+Logs::
+* Fix an authorization error when LogsPatternUsageService attempts to update `logsdb.prior_logs_usage` cluster setting. {es-pull}128050[#128050]
+
+Machine Learning::
+* Append all data to Chat Completion buffer {es-pull}127658[#127658]
+* Fix services API Google Vertex AI Rerank location field requirement {es-pull}127856[#127856]
+* Use internal user for internal inference action {es-pull}128327[#128327]
+
+Relevance::
+* Fix: Add `NamedWriteable` for `RuleQueryRankDoc` {es-pull}128153[#128153] (issue: {es-issue}126071[#126071])
+
+Security::
+* Remove dangling spaces wherever found {es-pull}127475[#127475]
+
+Snapshot/Restore::
+* Add missing entitlement to `repository-azure` {es-pull}128047[#128047] (issue: {es-issue}128046[#128046])
+
+TSDB::
+* Skip the validation when retrieving the index mode during reindexing a time series data stream {es-pull}127824[#127824]
+
+[[enhancement-8.18.2]]
+[float]
+=== Enhancements
+
+Authentication::
+* Http proxy support in JWT realm {es-pull}127337[#127337] (issue: {es-issue}114956[#114956])
+
+

docs/reference/release-notes/highlights.asciidoc

@@ -33,12 +33,35 @@ Other versions:
 
 endif::[]
 
-// The notable-highlights tag marks entries that
-// should be featured in the Stack Installation and Upgrade Guide:
 // tag::notable-highlights[]
-// [discrete]
-// === Heading
-//
-// Description.
+
+[discrete]
+[[add_new_experimental_rank_vectors_mapping_for_late_interaction_second_order_ranking]]
+=== `rank_vectors` field type is now available for late-interaction ranking
+
+<<rank-vectors,`rank_vectors`>> is a new field type released as an experimental feature in {es} {minor-version}. It is designed to be used with dense vectors and allows for late-interaction second order ranking.
+
+Late-interaction models are powerful rerankers. While their size and overall cost doesn't lend itself for HNSW indexing, utilizing them as second order reranking can provide excellent boosts in relevance. The new `rank_vectors` mapping allows for rescoring over new and novel multi-vector late-interaction models like ColBERT or ColPali.
+
+[discrete]
+[[enable_lookup_join_in_non_snapshot_builds]]
+=== {esql} LOOKUP JOIN is now available in technical preview
+
+<<esql-lookup-join,LOOKUP JOIN>> is now available in technical preview.
+LOOKUP JOIN combines data from your {esql} queries with matching records from a lookup index, enabling you to:
+
+* Enrich your search results with reference data
+* Speed up root-cause analysis and security investigations 
+* Join data across indices without complex queries
+* Reduce operational overhead when correlating events
+
+[discrete]
+[[release_semantic_text_as_ga_feature]]
+=== The `semantic_text` field type is now GA
+
+<<semantic-text,`semantic_text`>> is now an official GA (generally available) feature! This field type allows you to easily set up and perform semantic search with minimal ramp up time.
+
+
 // end::notable-highlights[]
 
+