fix: native llama reasoning stream and provider options

[JKobrynski]

Related issue - #199

Summary

Improves the @react-native-ai/llama streaming adapter by preferring native parsed reasoning/content fields from llama.rn when they are available, instead of relying only on placeholder parsing of raw token text.
Previously, the adapter inferred reasoning boundaries entirely from streamed token markers like <think>...</think>. That fallback parser remains useful, but newer llama.rn versions can expose native structured fields such as tokenData.reasoning_content and tokenData.content, which are a more reliable source of truth.
This change updates the stream parser to use native parsed fields when present, emit proper incremental deltas from their accumulated values, preserve fallback placeholder parsing when native fields are absent, and keep tool-call behavior intact across both paths.

Changes

• Prefer native tokenData.reasoning_content for reasoning stream output when available
• Prefer native tokenData.content for normal text stream output when available
• Track previously emitted native values and emit only new suffixes as deltas
• Preserve fallback placeholder parsing when native fields are absent
• Prevent duplicate text/reasoning emission when native fields and raw token text coexist on the same chunk
• Ensure buffered fallback text is still flushed safely after native chunks
• Preserve queued tool-call emission even when native parsed fields are present on a chunk
• Keep <think> markers inside tool-call payload text untouched
• Keep split <think> markers inside tool-call payload text untouched
• Extract llama completion option building into buildLlamaCompletionOptions
• Add focused unit tests for providerOptions.llama passthrough
• Export the completion-options helper from the llama package entrypoint

Testing

• Ran bun test packages/llama/src/__tests__/streamParser.test.ts
• Ran bun test packages/llama/src/__tests__/completionOptions.test.ts
• Ran ./node_modules/.bin/tsc --noEmit --project packages/llama/tsconfig.json
• Ran ./node_modules/.bin/tsc --noEmit --project packages/llama/tsconfig.build.json
• Ran bun lint
• Added regression coverage for:
  • native reasoning/content delta emission from accumulated values
  • native chunks that also include raw token text
  • fallback placeholder parsing when native fields are absent
  • buffered fallback flushing after native chunks
  • tool-call payloads containing <think> markers
  • split <think> markers inside tool-call payloads
  • queued tool-call emission from native chunks

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Pull request overview

This PR updates the @react-native-ai/llama adapter to (1) prefer native structured streaming fields (tokenData.reasoning_content / tokenData.content) when available, and (2) forward providerOptions.llama into llama.rn completion options via a shared builder helper.

Changes:

• Update the stream parser to emit incremental deltas based on native accumulated reasoning_content / content fields, while keeping the placeholder-based fallback path.
• Extract completion option construction into buildLlamaCompletionOptions and add providerOptions.llama passthrough.
• Add/extend unit tests for native streaming behavior and completion option passthrough.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/llama/src/streamParser.ts	Prefer native parsed content/reasoning_content and emit suffix deltas; adjust tool-call flushing logic.
packages/llama/src/completionOptions.ts	New helper for preparing messages (multimodal) and building completion options with providerOptions.llama passthrough.
packages/llama/src/ai-sdk.ts	Refactor to use shared completion-options builder and message preparation helper.
packages/llama/src/index.ts	Export completion-options helpers from the package entrypoint.
packages/llama/src/tests/streamParser.test.ts	Add coverage for native parsed streaming and tool-call edge cases.
packages/llama/src/tests/completionOptions.test.ts	Add focused tests for providerOptions.llama passthrough behavior.

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[JKobrynski]

Good point, addressed