✓ PASS

vercel-ai 7.0.153

stream.utf8 · anthropic

Requirements

Id	Level	Status	Evidence
text-reported	MUST	SATISFIED	text.value="Café Zürich — καλημέρα! 東京で会いましょう 🌸🎉" (primary); truth.text="Café Zürich — καλημέρα! 東京で会いましょう 🌸🎉"
no-replacement-chars	MUST	SATISFIED	text.value="Café Zürich — καλημέρα! 東京で会いましょう 🌸🎉" (primary); U+FFFD count=0

What the provider sent

Finish: stop
Raw finish: end_turn
Text: Café Zürich — καλημέρα! 東京で会いましょう 🌸🎉
Tool calls: []
Usage: { "alternatives": {}, "cached_input": null, "input": 25, "output": 40, "raw": { "input_tokens": 25, "output_tokens": 40 }, "reasoning": null, "total": 65 }
Stream completed: true
Error: null

Wire excerpt

status: 200
content-type: text/event-stream
body (sse):
event: message_start
data: {"type": "message_start", "message": {"id": "msg_01Aq9w938a90dw8q", "type": "message", "role": "assistant", "content": [], "model": "claude-sonnet-5-5", "stop_reason": null, "stop_sequence": null, "usage": {"input_tokens": 25, "output_tokens": 1}}}


event: content_block_start
data: {"type": "content_block_start", "index": 0, "content_block": {"type": "text", "text": ""}}


event: ping
data: {"type": "ping"}


event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": "Café "}}


event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": "Zürich — καλημέρα! 東京で会いましょう 🌸🎉"}}


event: content_block_stop
data: {"type": "content_block_stop", "index": 0}


event: message_delta
data: {"type":"message_delta","delta":{"stop_reason":"end_turn","stop_sequence":null},"usage":{"output_tokens":40}}


event: message_stop
data: {"type": "message_stop"}

What the library reported

Outcome

returned

Finish

{
  "raw": "end_turn",
  "source": "fullStream.finish.finishReason",
  "surface": "primary",
  "value": "stop"
}

Text

Value: Café Zürich — καλημέρα! 東京で会いましょう 🌸🎉
Surface: primary

Tool calls

[]

Usage

{
  "cached_input": 0,
  "input": 25,
  "output": 40,
  "reasoning": null,
  "surface": {
    "cached_input": "primary",
    "input": "primary",
    "output": "primary",
    "reasoning": "absent",
    "total": "primary"
  },
  "total": 65
}

Stream

{
  "chunks_seen": 9,
  "completed": true,
  "used": true
}

Error

null

Unsupported reason

null

Full observation JSON

{
  "elapsed_ms": 161.06262400000003,
  "error": null,
  "finish": {
    "raw": "end_turn",
    "source": "fullStream.finish.finishReason",
    "surface": "primary",
    "value": "stop"
  },
  "format": "wiretruth.observation/v1",
  "library": {
    "api": "streamText",
    "language": "javascript",
    "name": "vercel-ai",
    "version": "7.0.153"
  },
  "notes": [],
  "outcome": "returned",
  "stream": {
    "chunks_seen": 9,
    "completed": true,
    "used": true
  },
  "structured": {
    "attempted": false,
    "returned_as_success": false,
    "value": null
  },
  "text": {
    "surface": "primary",
    "value": "Café Zürich — καλημέρα! 東京で会いましょう 🌸🎉"
  },
  "tool_calls": [],
  "unsupported_reason": null,
  "usage": {
    "cached_input": 0,
    "input": 25,
    "output": 40,
    "reasoning": null,
    "surface": {
      "cached_input": "primary",
      "input": "primary",
      "output": "primary",
      "reasoning": "absent",
      "total": "primary"
    },
    "total": 65
  }
}

Fixture

documented anthropic/stream.utf8

Provenance	Value
Source	https://platform.claude.com/docs/en/build-with-claude/streaming#basic-streaming-request
Notes	Documented shapes, not a recording. Message envelope and stop fields follow handling-stop-reasons; content blocks follow thinking/streaming and handle-tool-calls. Model changed to claude-sonnet-5-5; IDs and scenario text are filled in. Token counts are illustrative, filled in to include thinking within the requested output limit, not measured. Based on the basic Hello stream, substituting the requested accented Latin, Greek, Japanese and emoji text. Each text fragment occurs once in the response. Adaptive thinking is assumed skipped. UTF-8 byte boundaries are unchanged here; the derived variant splits characters. SSE names, JSON shapes, field order and spaced text/thinking events follow streaming examples; the compact message_delta follows Streaming request with tool use. Fragment boundaries and counts are filled in. Signature placeholder is copied literally from the signature_delta example; empty thinking_delta follows the documented omitted display flow.

Provenance

Value

Source

https://platform.claude.com/docs/en/build-with-claude/streaming#basic-streaming-request

Notes

Documented shapes, not a recording. Message envelope and stop fields follow handling-stop-reasons; content blocks follow thinking/streaming and handle-tool-calls. Model changed to claude-sonnet-5-5; IDs and scenario text are filled in. Token counts are illustrative, filled in to include thinking within the requested output limit, not measured. Based on the basic Hello stream, substituting the requested accented Latin, Greek, Japanese and emoji text. Each text fragment occurs once in the response. Adaptive thinking is assumed skipped. UTF-8 byte boundaries are unchanged here; the derived variant splits characters. SSE names, JSON shapes, field order and spaced text/thinking events follow streaming examples; the compact message_delta follows Streaming request with tool use. Fragment boundaries and counts are filled in. Signature placeholder is copied literally from the signature_delta example; empty thinking_delta follows the documented omitted display flow.

Reproduce

wiretruth serve anthropic/stream.utf8

Plain-library snippet from the shim manifest.

createAnthropic({ baseURL: WIRETRUTH_BASE_URL_ANTHROPIC + '/v1', apiKey })(model)

Upstream

No matching upstream report.

History

Version	Grade
7.0.153	✓ PASS
7.0.146	✓ PASS
7.0.142	✓ PASS