fix(ai): tolerate empty-string tool call id/name in streaming deltas

[Garfier]

Issue for this PR

Closes#37841

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Some OpenAI-compatible APIs (e.g. DashScope token-plan / GLM-5.2) send empty strings for id and function.name on subsequent tool call deltas instead of omitting them or sending null. ToolStream.appendOrStart uses ?? (nullish coalescing) to fall back to accumulated identity from the first delta, but "" is not nullish so the fallback never triggers, and !id / !name then fails with "OpenAI Chat tool call delta is missing id or name".

The fix treats empty strings as absent by using || before ??:

constid=(delta.id||undefined)??current?.idconstname=(delta.name||undefined)??current?.name

This preserves the accumulated identity from the first delta (which does contain valid id and name) when subsequent deltas send empty strings.

How did you verify your code works?

• Added a test case simulating the DashScope token-plan streaming format (first delta with valid id/name, subsequent deltas with empty strings). All 8 tests in tool-stream.test.ts pass.
• Verified against the real token-plan API (token-plan.cn-beijing.maas.aliyuncs.com) with GLM-5.2 by curling a streaming tool call request and confirming the empty-string delta pattern.
• Built a local binary and confirmed tool calls work end-to-end with the fix.

Screenshots / recordings

N/A (not a UI change)

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on the search results, I found one potentially related PR:

Related PR:

• fix(opencode): prevent spurious tool events from Qwen 3.7 Plus/Max via OpenRouter #33622: fix(opencode): prevent spurious tool events from Qwen 3.7 Plus/Max via OpenRouter
  • fix(opencode): prevent spurious tool events from Qwen 3.7 Plus/Max via OpenRouter #33622
  • Why related: This PR also addresses compatibility issues with OpenAI-compatible APIs sending malformed or unexpected tool call data during streaming. While it targets a different provider (Qwen 3.7), it appears to be part of a pattern of handling non-standard tool call behavior from various LLM providers.

However, #33622 is not a duplicate—it addresses a different issue with a different provider. This PR (#37842) is specifically about tolerating empty strings in tool call id and name fields from DashScope/GLM-5.2, which is a distinct problem from the spurious events issue in Qwen.

[Garfier]

Closing: upstream v2 already includes an equivalent fix (prefer accumulated identity over delta values). The upstream approach current?.id ?? delta.id is cleaner. Glad to see this resolved!