fix: preserve anthropic assistant ids in tool-first streams

[shaked-frame]

Summary

• add parentMessageId to Anthropic TOOL_CALL_START chunks so tool-first streams bind to the eventual assistant message id immediately
• add an Anthropic adapter regression covering tool-first streams and asserting the tool call chunk references the same assistant message id as TEXT_MESSAGE_START
• add a stream processor regression showing tool-first flows with parentMessageId preserve a single assistant message instead of creating a temporary local id

fixes#477

Verification

• pnpm exec vitest run packages/typescript/ai/tests/stream-processor.test.ts
• pnpm test:lib -- --runInBand in packages/typescript/ai
  • the new stream-processor regression passed
  • the package command still hits existing workspace resolution issues (@tanstack/ai-event-client, examples/ts-svelte-chat/.svelte-kit/tsconfig.json)
• pnpm test:lib -- --runInBand in packages/typescript/ai-anthropic
  • blocked by an existing @tanstack/ai package-entry resolution issue before the adapter test file runs

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Fixed an issue where streaming tool calls would create temporary message IDs that changed mid-stream. Tool calls are now properly bound to their parent assistant messages, ensuring stable message IDs throughout streaming across all supported providers.

[coderabbitai]

Note

Reviews paused

It looks like this branch is under active development. To avoid overwhelming you with review comments due to an influx of new commits, CodeRabbit has automatically paused this review. You can configure this behavior by changing the reviews.auto_review.auto_pause_after_reviewed_commits setting.

Use the following commands to manage reviews:

• @coderabbitai resume to resume automatic reviews.
• @coderabbitai review to trigger a single review.

Use the checkboxes below for quick actions:

• ▶️ Resume reviews
• 🔍 Trigger review

📝 Walkthrough

Walkthrough

This PR adds a changeset file documenting a fix for AG-UI stream handling. Tool call start events now include parentMessageId to bind them to the stable assistant message id, preventing temporary message creation and mid-stream id changes when tool calls arrive before text across all provider adapters.

Changes

Stream Stability Fix Release Notes

Layer / File(s)	Summary
Stream stability fix changelog .changeset/tool-first-parent-message-id.md	Changeset documenting the fix where TOOL_CALL_START events now carry parentMessageId tied to the per-stream assistant message id, preventing StreamProcessor from creating temporary messages that would later cause mid-stream id changes. The fix spans all adapters: Anthropic, OpenAI (Responses and Chat Completions), OpenRouter, Gemini (including experimental text-interactions), and Ollama.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Suggested reviewers

• tombeckenham
• AlemTuzlak

Poem

A bunny's stream now flows so true,
Tool calls bind to parent, tried and new,
No id remounts in mid-stream glow—
Stability fixed from head to toe! 🐰✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Description check	❓ Inconclusive	The description covers key aspects but lacks evidence of PR checklist completion and changeset generation verification, which the template requires.	Clarify whether the Contributing guide steps were followed and confirm changeset was created as required by the template checklist.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main fix: preserving Anthropic assistant IDs in tool-first streams, which is the primary objective of this changeset.
Linked Issues check	✅ Passed	The PR successfully addresses issue #477 by implementing parentMessageId on TOOL_CALL_START chunks, stabilizing assistant message IDs through tool-first streams as required.
Out of Scope Changes check	✅ Passed	All changes focus on fixing the tool-first stream ID stability issue in issue #477; the changeset entry documents the fix without introducing unrelated modifications.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[shaked-frame]

rebased and pushed after resolving conflicts

[tombeckenham]

Thanks for this. I fixed it in the rest of the adpaters as well.

[nx-cloud]

View your CI Pipeline Execution ↗ for commit 683fb09

Command	Status	Duration	Result
nx run-many --targets=build --exclude=examples/...	✅ Succeeded	25s	View ↗

---

☁️ Nx Cloud last updated this comment at 2026-06-23 09:34:21 UTC

[pkg-pr-new]

Open in StackBlitz

@tanstack/ai

npm i https://pkg.pr.new/@tanstack/ai@480

@tanstack/ai-angular

npm i https://pkg.pr.new/@tanstack/ai-angular@480

@tanstack/ai-anthropic

npm i https://pkg.pr.new/@tanstack/ai-anthropic@480

@tanstack/ai-client

npm i https://pkg.pr.new/@tanstack/ai-client@480

@tanstack/ai-code-mode

npm i https://pkg.pr.new/@tanstack/ai-code-mode@480

@tanstack/ai-code-mode-skills

npm i https://pkg.pr.new/@tanstack/ai-code-mode-skills@480

@tanstack/ai-devtools-core

npm i https://pkg.pr.new/@tanstack/ai-devtools-core@480

@tanstack/ai-elevenlabs

npm i https://pkg.pr.new/@tanstack/ai-elevenlabs@480

@tanstack/ai-event-client

npm i https://pkg.pr.new/@tanstack/ai-event-client@480

@tanstack/ai-fal

npm i https://pkg.pr.new/@tanstack/ai-fal@480

@tanstack/ai-gemini

npm i https://pkg.pr.new/@tanstack/ai-gemini@480

@tanstack/ai-grok

npm i https://pkg.pr.new/@tanstack/ai-grok@480

@tanstack/ai-groq

npm i https://pkg.pr.new/@tanstack/ai-groq@480

@tanstack/ai-isolate-cloudflare

npm i https://pkg.pr.new/@tanstack/ai-isolate-cloudflare@480

@tanstack/ai-isolate-node

npm i https://pkg.pr.new/@tanstack/ai-isolate-node@480

@tanstack/ai-isolate-quickjs

npm i https://pkg.pr.new/@tanstack/ai-isolate-quickjs@480

@tanstack/ai-mcp

npm i https://pkg.pr.new/@tanstack/ai-mcp@480

@tanstack/ai-ollama

npm i https://pkg.pr.new/@tanstack/ai-ollama@480

@tanstack/ai-openai

npm i https://pkg.pr.new/@tanstack/ai-openai@480

@tanstack/ai-openrouter

npm i https://pkg.pr.new/@tanstack/ai-openrouter@480

@tanstack/ai-preact

npm i https://pkg.pr.new/@tanstack/ai-preact@480

@tanstack/ai-react

npm i https://pkg.pr.new/@tanstack/ai-react@480

@tanstack/ai-react-ui

npm i https://pkg.pr.new/@tanstack/ai-react-ui@480

@tanstack/ai-solid

npm i https://pkg.pr.new/@tanstack/ai-solid@480

@tanstack/ai-solid-ui

npm i https://pkg.pr.new/@tanstack/ai-solid-ui@480

@tanstack/ai-svelte

npm i https://pkg.pr.new/@tanstack/ai-svelte@480

@tanstack/ai-utils

npm i https://pkg.pr.new/@tanstack/ai-utils@480

@tanstack/ai-vue

npm i https://pkg.pr.new/@tanstack/ai-vue@480

@tanstack/ai-vue-ui

npm i https://pkg.pr.new/@tanstack/ai-vue-ui@480

@tanstack/openai-base

npm i https://pkg.pr.new/@tanstack/openai-base@480

@tanstack/preact-ai-devtools

npm i https://pkg.pr.new/@tanstack/preact-ai-devtools@480

@tanstack/react-ai-devtools

npm i https://pkg.pr.new/@tanstack/react-ai-devtools@480

@tanstack/solid-ai-devtools

npm i https://pkg.pr.new/@tanstack/solid-ai-devtools@480

commit: 683fb09