Add SPLIT_PART string function to the SQL interface (#22158)
Allow scalar expr in Expr.diff (#22142)
Support additional unsigned int aliases in the SQL interface (#22127)
Add STRING_TO_ARRAY function to the SQL interface (#22129)
Add dt.is_business_day (#21776)
Add an eager parameter to pl.cov (#22098)
Add support for Int128 parsing/recognition to the SQL interface (#22104)
Add an eager parameter to pl.coalesce (#22092)
Add an eager parameter to pl.corr (#22097)
Allow sinking to abstract python io and fs classes (#21987)
Add add_alp_optimize_exprs to IRBuilder (#22061)
Add cat.slice (#21971)
Support growing schema if line lenght increases during csv schema inference (#21979)
Replace thread unsafe GilOnceCell with Mutex (#21927)
Support modified dsl in file cache (#21907)

🐞 Bug fixes

Implode in agg (#22197)
Reduce GIL hold time for IO plugins in new-streaming (#22186)
Enhance predicate validation and cast safety in join_where (#22112)
Handle Parquet with compressed empty DataPage v2 (#22172)
Schema error during lowering (#22175)
Rewrite unroll of overlapping groups to mitigate out of range index panic (#22072)
Incorrect rounding for very large/small numbers (#22173)
Allow set input to list.set_* operations (#22163)
Deadlock in join due to rayon nested task-stealing (#22159)
Mark Expr.repeat_by as elementwise (#22068)
Fix csv serializer panic by supporting ScalarColumn in as_single_chunk (#22146)
Raise an error if a number doesn't have associated unit in duration strings (#22035)
Add i128 as supertype to boolean (#22138)
Fix panic when constructing DF from pyarrow due to duplicate field names (#22114)
Add broadcasts and error messages for many elementwise operations (#22130)
Throw error for n=0 on list.gather_every (#22122)
Throw error for unsupported rolling operations (#22121)
Error on unequal length str.to_integer arguments (#22100)
Make bottom interval closed in hist (#22090)
Relative path resolution for plugin libraries (#21911)
Avoiding panic with striptime for out-of-bounds dates (#21208)
Join revmaps for categoricals in merge_sorted (#21976)
Fix glob expansion matching extra files (#21991)
Ensure SQL dot-notation for nested column fields resolves correctly (#22109)
Parquet filter performance regression from multiscan dispatch (#22116)
Panic for unequal length ewm_mean_by args (#22093)
Add scalarity checks to pl.repeat (#22088)
Type check n parameter of pl.repeat (#22071)
Mark bitwise_{count,leading,trailing}_{ones,zeros} as elementwise (#22044)
Mark pl.*_ranges functions correctly as element-wise (#22059)
Correctly type check pl.arctan2 (#22060)
Mark pl.business_day_count as elementwise (#22055)
Check input python type for str.extract_groups (#22032)
Check types for fill_char in str.pad_{start,end} (#22036)
Mark str.to_decimal properly as non-elementwise (#22040)
Documented return type for bin.encode and bin.decode (#22022)
Revert #22017 and improve block(_in_place)_on doc comment (#22031)
Remove outdated depth warning (#22030)
Expression pl.concat was incorrectly marked as elementwise (#22019)
Use block_in_place_on to start streaming (#22017)
Panic on empty aggregation in streaming (#22016)
Error instead of panick for invalid durations in dt.offset_by() and dt.round() (#21982)
Raise error instead of silently appending NULL in NDJSON parsing (#21953)
Ensure AV is static before pushing to row buffer (#21967)
Deadlock in new-streaming multiplexer (#21963)
Release GIL in collect_with_callback (#21941)
Panic in new RegexCache (#21935)
Type hint of cs.exclude() is SelectorType instead of Expr (#21892)
Add correct deprecation warning for .str.concat (#21666)
Use absolute paths by defaults for plugins (#21904)

📖 Documentation

Add user guide section on working with Sheets in Colab (#22161)
Update distributed engine docs (#22128)
Add Polars Cloud release notes (#22021)
Remove trailing space in settings POLARS_CLOUD_CLIENT_ID (#21995)
Fix typo (#21954)
Fix 'pickleable' typo in docs (#21938)
Change ctx to compute=ctx for all remote query examples (#21930)

🛠️ Other improvements

Remove old MultiScanExec for in-memory (#22184)
Separate FunctionOptions from DSL calls (#22133)
Undeprecate backward_fill and forward_fill (#22156)
Handle conversion of Duration specially in pyir (#22101)
Deprecate duplicate backward_fill and forward_fill interface (#22083)
Solve clippy lints for 1.86 (#22102)
Remove rust exclusive MaxBound and MinBound fill strategies (#22063)
Change Partition API to base_path and file_path (#21888)
Fix pydantic model_fields deprecation (#21958)

Thank you to all our contributors for making this release possible! @DeflateAwning, @EnricoMi, @Jacob640, @JakubValtar, @MarcoGorelli, @MaxJackson, @alexander-beedie, @amotzop, @anath2, @bschoenmaeckers, @cnpryer, @coastalwhite, @dependabot[bot], @eitsupi, @etiennebacher, @hemanth94, @kdn36, @mcrumiller, @nameexhaustion, @orlp, @r-brink, @rgertenbach, @ritchie46, @sebasv, @silannisik, @stijnherfst, @wence-, @zachlefevre and dependabot[bot]