rig-core-v0.38.0

### Added

- *(rig-derive)* replace hand-rolled schema with schemars in #[rig_tool] ([#1576](https://github.com/0xPlaygrounds/rig/pull/1576)) (by @tomasz-feliksik)
- *(embeddings)* expose token usage via embed_texts_with_usage ([#1791](https://github.com/0xPlaygrounds/rig/pull/1791)) (by @sergiomeneses)
- *(openrouter)* add prompt-caching support ([#1832](https://github.com/0xPlaygrounds/rig/pull/1832)) (by @gold-silver-copper)
- *(openrouter)* add with_app_identity and with_app_categories builders for app attribution ([#1806](https://github.com/0xPlaygrounds/rig/pull/1806)) (by @jimmiebfulton)
- *(openrouter)* surface cache token accounting in Usage ([#1808](https://github.com/0xPlaygrounds/rig/pull/1808)) (by @jimmiebfulton)
- *(gemini)* expose streaming response metadata ([#1790](https://github.com/0xPlaygrounds/rig/pull/1790)) (by @mateobelanger)
- *(anthropic)* support document citations ([#1778](https://github.com/0xPlaygrounds/rig/pull/1778)) (by @temrjan)
- *(gemini)* expose finish_reason and model_version on StreamingCompletionResponse ([#1776](https://github.com/0xPlaygrounds/rig/pull/1776)) (by @mateobelanger)

### Fixed

- *(openai)* tolerate object-form tool-call `arguments` in streaming ([#1822](https://github.com/0xPlaygrounds/rig/pull/1822)) (by @xavierforge)
- *(chatgpt)* Handle ChatGPT response.completed events without output field ([#1825](https://github.com/0xPlaygrounds/rig/pull/1825)) (by @geraschenko)
- *(rig-core)* Expose tools added via ToolServerHandle::append_toolset ([#1837](https://github.com/0xPlaygrounds/rig/pull/1837)) (by @mccormickt)
- avoid duplicate streaming reasoning history ([#1849](https://github.com/0xPlaygrounds/rig/pull/1849)) (by @gold-silver-copper) - #1849
- *(rig-gemini-grpc)* populate FunctionDeclaration.parameters from ToolDefinition ([#1763](https://github.com/0xPlaygrounds/rig/pull/1763)) (by @abhicris)
- *(openrouter)* avoid replaying generated images ([#1835](https://github.com/0xPlaygrounds/rig/pull/1835)) (by @gold-silver-copper)
- *(openrouter)* accept Gemini model role responses ([#1800](https://github.com/0xPlaygrounds/rig/pull/1800)) (by @puneetdixit200)
- *(tools)* safely normalize null tool call arguments ([#1814](https://github.com/0xPlaygrounds/rig/pull/1814)) (by @gold-silver-copper)
- *(ollama)* buffer NDJSON streaming across HTTP chunk boundaries bytes_stream may split a single NDJSON line across chunks, causing serde_json::from_slice to fail mid-stream with an EOF error on longer assistant messages ([#1759](https://github.com/0xPlaygrounds/rig/pull/1759)) (by @ChadBartley)
- *(gemini)* record tool use prompt token telemetry ([#1799](https://github.com/0xPlaygrounds/rig/pull/1799)) (by @gold-silver-copper)
- default OpenAI base64 image detail ([#1781](https://github.com/0xPlaygrounds/rig/pull/1781)) (by @fangkangmi) - #1781
- stream ToolCallDelta in prompt_request ([#1789](https://github.com/0xPlaygrounds/rig/pull/1789)) (by @notV4l) - #1789
- fix sqlite threshold and null tool call streaming ([#1786](https://github.com/0xPlaygrounds/rig/pull/1786)) (by @gold-silver-copper) - #1786
- *(anthropic)* serialize ToolResultContent::Image with source wrapper ([#1772](https://github.com/0xPlaygrounds/rig/pull/1772)) (by @Cyanistic)

### Other

- Fix parsing of streamed function-call argument deltas ([#1828](https://github.com/0xPlaygrounds/rig/pull/1828)) (by @geraschenko) - #1828
- Add invalid tool call recovery hooks ([#1840](https://github.com/0xPlaygrounds/rig/pull/1840)) (by @gold-silver-copper) - #1840
- [codex] Validate model tool calls ([#1823](https://github.com/0xPlaygrounds/rig/pull/1823)) (by @gold-silver-copper) - #1823
- Cap OpenRouter app categories header ([#1821](https://github.com/0xPlaygrounds/rig/pull/1821)) (by @gold-silver-copper) - #1821
- [codex] apply Anthropic cache control to tools ([#1815](https://github.com/0xPlaygrounds/rig/pull/1815)) (by @gold-silver-copper) - #1815
- Expose per-completion-call usage in agent responses ([#1787](https://github.com/0xPlaygrounds/rig/pull/1787)) (by @gold-silver-copper) - #1787
- Add replayable provider cassette tests ([#1769](https://github.com/0xPlaygrounds/rig/pull/1769)) (by @gold-silver-copper) - #1769

### Contributors

* @xavierforge
* @geraschenko
* @mccormickt
* @gold-silver-copper
* @tomasz-feliksik
* @sergiomeneses
* @abhicris
* @jimmiebfulton
* @puneetdixit200
* @ChadBartley
* @mateobelanger
* @temrjan
* @fangkangmi
* @notV4l
* @Cyanistic