release: 2.12.0

[stainless-app]

Automated Release PR

2.12.0 (2026-01-16)

Full Changelog: v2.11.1...v2.12.0

Features

• api: Add new methods to tests (#748) (2c2ebdc)
• api: adds support for Claude Opus 4.5, Effort, Advance Tool Use Features, Autocompaction, and Computer Use v5 (4689271)
• api: migrate sending message format in output_config rather than output_format (c0103c6)
• api: migrate sending message format in output_config rather than output_format (a6ea665)
• client: add HttpRequest#url() method (49afe52)
• client: allow configuring dispatcher executor service (60554ea)
• client: support Anthropic models on Microsoft Foundry (#698) (8077051)

Bug Fixes

• client: BetaMessageAccumulator crash on empty tool input (e0fe678)
• client: cancel okhttp call when future cancelled (b52f783)
• client: implement visitToolSearchToolResult for Beta Accumulator (41191ed)
• client: run linter (73e141d)
• date time deserialization leniency (f6f7ad1)

Chores

• ci: add Claude Code GitHub Workflow (4eec6e8)
• client: mark claude-3-5-haiku as deprecated (46bf679)
• fix merge conflict (e307fa0)
• fix test (b612010)
• internal: clean up maven repo artifact script and add html documentation to repo root (d319dd7)
• internal: support uploading Maven repo artifacts to stainless package server (17e663a)
• internal: use different example values for some enums (5d45a2f)
• test on Jackson 2.14.0 to avoid encountering FasterXML/jackson-databind#3240 in tests (f6f7ad1)

Documentation

• remove $ for better copy-pasteabality (b2315f9)

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[TimMillerDyck]

Hi, we are eager to get Opus 4.5 support in the Java client library and so looking forward to the 2.12.0 release here. Thanks.

[TomerAberbach]

Hi, we are eager to get Opus 4.5 support in the Java client library and so looking forward to the 2.12.0 release here. Thanks.

Need to fix up some tests, but for now you can pass a plain string for any .model(...) param (or pass Model.of(...))

[TimMillerDyck]

Need to fix up some tests, but for now you can pass a plain string for any .model(...) param (or pass Model.of(...))

Thank you so much for your response, @TomerAberbach. It's great getting a response from someone on the project.

FYI, we use the library's native Model class to validate model selection input in our own internal AI APIs so we would have to recode some validation logic and switch data types to plain strings in a number of places to bypass the native enum. I'm hoping to just update to v2.12.0 and avoid that. We appreciate the work that has gone into this library.