~ LOSSY

any-llm 1.40.2

stream.missing-finish · anthropic

Requirements

Id	Level	Status	Evidence
no-normal-stop	MUST	SATISFIED	outcome=returned; finish.value=null (absent); truth.finish="none"; forbidden finish="stop"
stream-incomplete	MUST	NOT_OBSERVABLE	stream.completed=null; outcome=returned; truth.stream_completed=false

What the provider sent

Finish: none
Raw finish: null
Text: Octopuses change colour by
Tool calls: []
Usage: { "alternatives": {}, "cached_input": null, "input": 25, "output": 1, "raw": { "input_tokens": 25, "output_tokens": 1 }, "reasoning": null, "total": 26 }
Stream completed: false
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": "thinking", "thinking": "", "signature": ""}}


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


event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": ""}}


event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "signature_delta", "signature": "EqQBCgIYAhIM1gbcDa9GJwZA2b3hGgxBdjrkzLoky3dl1pkiMOYds..."}}


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


event: content_block_start
data: {"type": "content_block_start", "index": 1, "content_block": {"type": "text", "text": ""}}


event: content_block_delta
data: {"type": "content_block_delta", "index": 1, "delta": {"type": "text_delta", "text": "Octopuses "}}


event: content_block_delta
data: {"type": "content_block_delta", "index": 1, "delta": {"type": "text_delta", "text": "change colour by"}}


event: content_block_stop
data: {"type": "content_block_stop", "index": 1}

What the library reported

Outcome

returned

Finish

{
  "raw": null,
  "source": null,
  "surface": "absent",
  "value": null
}

Text

Value: Octopuses change colour by
Surface: primary

Tool calls

[]

Usage

{
  "cached_input": null,
  "input": null,
  "output": null,
  "reasoning": null,
  "surface": {
    "cached_input": "absent",
    "input": "absent",
    "output": "absent",
    "reasoning": "absent",
    "total": "absent"
  },
  "total": null
}

Stream

{
  "chunks_seen": 13,
  "completed": null,
  "used": true
}

Error

null

Unsupported reason

null

Full observation JSON

{
  "elapsed_ms": 170.41339445859194,
  "error": null,
  "finish": {
    "raw": null,
    "source": null,
    "surface": "absent",
    "value": null
  },
  "format": "wiretruth.observation/v1",
  "library": {
    "api": "any_llm.completion",
    "language": "python",
    "name": "any-llm",
    "version": "1.40.2"
  },
  "notes": [],
  "outcome": "returned",
  "stream": {
    "chunks_seen": 13,
    "completed": null,
    "used": true
  },
  "structured": {
    "attempted": false,
    "returned_as_success": false,
    "value": null
  },
  "text": {
    "surface": "primary",
    "value": "Octopuses change colour by"
  },
  "tool_calls": [],
  "unsupported_reason": null,
  "usage": {
    "cached_input": null,
    "input": null,
    "output": null,
    "reasoning": null,
    "surface": {
      "cached_input": "absent",
      "input": "absent",
      "output": "absent",
      "reasoning": "absent",
      "total": "absent"
    },
    "total": null
  }
}

Fixture

derived anthropic/stream.missing-finish

Provenance	Value
Transform	strip_finish
Source fixture	anthropic/truncation.text-stream
Rationale	The stream ends cleanly without its finish signal.
Evidence	https://platform.claude.com/docs/en/build-with-claude/streaming#event-types

Reproduce

wiretruth serve anthropic/stream.missing-finish

Plain-library snippet from the shim manifest.

any_llm.completion(model=model, provider='anthropic', api_base=WIRETRUTH_BASE_URL_ANTHROPIC, api_key=WIRETRUTH_API_KEY); host root, SDK appends /v1/messages and uses x-api-key

Upstream

reported Issue

Fixed in: not specified

A stream that ends before the provider's terminal signal returns the partial chunks normally, with no error and no incomplete flag (reproduced on 1.40.2 and 1.50.0). The OpenAI Responses path reports the output item as incomplete and passes.

History

Version	Grade
1.40.2	~ LOSSY
1.38.0	~ LOSSY
1.33.0	~ LOSSY