olp/docs/openai-spec-pin.md

OpenAI Spec Pin (v0.1 baseline)

• Date pinned: 2026-05-24 (D30)
• Status: v0.1 baseline — annual audit per ALIGNMENT.md § Annual Alignment Audit
• Authority: OpenAI Chat Completions API + Models API

This document is the spec-diff baseline against which OLP's annual audit will compare future OpenAI spec changes. It enumerates the specific spec sections OLP currently implements as the entry surface, verified against lib/ir/openai-to-ir.mjs and lib/ir/ir-to-openai.mjs at the time of pinning.

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Endpoints implemented

POST /v1/chat/completions

• Spec section: https://platform.openai.com/docs/api-reference/chat/create
• Retrieval timestamp: 2026-05-24

Request body fields supported (translated into IR by openAIToIR in lib/ir/openai-to-ir.mjs):

Field	Type	Required	Notes
model	string	required	Passed through to IR; validated non-empty
messages	array	required	Non-empty; each element translated via translateMessage
messages[i].role	string	required	system / user / assistant / tool; deprecated function normalized to tool
messages[i].content	string|null	required	null normalized to ''
messages[i].name	string	optional	Passed through to IR
messages[i].tool_call_id	string	optional	Passed through to IR
messages[i].tool_calls	array	optional	{id, type:'function', function:{name, arguments}}
messages[i].function_call	object	optional	Deprecated field; mapped to a single tool_calls entry
stream	boolean	optional	Default false; true triggers SSE path
temperature	number	optional	Range [0, 2]; passed to IR
max_tokens	integer	optional	Must be a positive integer; passed to IR
top_p	number	optional	Range [0, 1]; passed to IR
stop	string | array	optional	Passed to IR as-is
tools	array	optional	Only type:'function' tools supported; translated via translateTools
tools[i].function.name	string	required (in tool)	Passed through
tools[i].function.description	string	optional	Passed through if present
tools[i].function.parameters	object	optional	Passed through if present
tool_choice	'auto'|'none'|'required'|{type:'function',function:{name}}	optional	Passed to IR verbatim
response_format	object	optional	Passed to IR verbatim

Request body fields NOT yet supported (silently dropped by entry surface — not read in openAIToIR):

• n — multiple completions; OLP is single-completion only
• seed — deterministic sampling
• frequency_penalty, presence_penalty
• logit_bias
• logprobs, top_logprobs
• user
• service_tier
• parallel_tool_calls
• stream_options

Response shape (non-streaming) — object: 'chat.completion' (assembled by irResponseToOpenAINonStream in lib/ir/ir-to-openai.mjs):

{
  "id": "chatcmpl-<base64url>",
  "object": "chat.completion",
  "created": <unix-epoch-seconds>,
  "model": "<model-string-from-request>",
  "choices": [{
    "index": 0,
    "message": {
      "role": "assistant",
      "content": "<string-or-null>",
      "tool_calls": [ ... ]
    },
    "finish_reason": "<stop|length|tool_calls|content_filter|function_call|null>"
  }],
  "usage": { ... }
}

• usage is included only when the provider surfaces token counts on the final chunk.
• message.tool_calls is included only when tool calls are present.
• message.content is null when there is no text content and tool calls are present.

Response shape (streaming) — object: 'chat.completion.chunk' (emitted by irChunkToOpenAISSE in lib/ir/ir-to-openai.mjs):

data: {"id":"chatcmpl-...","object":"chat.completion.chunk","created":<ts>,"model":"<m>","choices":[{"index":0,"delta":{"role":"assistant","content":"..."},"finish_reason":null}]}

data: {"id":"chatcmpl-...","object":"chat.completion.chunk","created":<ts>,"model":"<m>","choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}

data: [DONE]

• delta carries role (first chunk only), content (text chunks), or tool_calls (tool call chunks).
• Final stop chunk has finish_reason set and empty delta.
• usage is included in the stop chunk only when the provider surfaces token counts.
• Stream terminator: data: [DONE]\n\n.

finish_reason enum honored (normalized by normalizeFinishReason; non-spec values normalized to 'stop'):

• stop — natural completion
• length — truncated at max_tokens or synthesized on truncation (D19/D16)
• tool_calls — model stopped to emit a tool call
• content_filter — provider-side content filter
• function_call — deprecated; preserved for backwards compatibility
• null — in-progress (streaming delta chunks)

Error response shape:

HTTP 4xx/5xx with body:

{ "error": { "message": "<string>", "type": "<string>" } }

No invented top-level error field on chat.completion objects (per ALIGNMENT.md Rule 2 — D12 finding). Errors surface exclusively via HTTP status codes with the above body shape.

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GET /v1/models

• Spec section: https://platform.openai.com/docs/api-reference/models/list
• Retrieval timestamp: 2026-05-24

Response shape (handleModels in server.mjs):

{ "object": "list", "data": [ ... ] }

Each entry: { "id": "<model-id>", "object": "model", "created": <ts>, "owned_by": "<provider-key>" } — no invented fields (per D27 F15). Alias entries are also surfaced as separate list members (per D27 F15 alias surfacing).

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GET /health

OLP-specific endpoint (not in OpenAI spec). Returns:

{ "ok": true, "version": "<semver>", "providers": { "enabled": <n>, "available": <n> } }

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Streaming SSE semantics

• MIME: text/event-stream
• Per-chunk framing: data: <json>\n\n
• Terminator: data: [DONE]\n\n
• Truncation marker: finish_reason: 'length' synthesized when the provider generator exhausts without a natural stop chunk (D26 F19 — mirrors D16 buffered-path semantics)
• Response headers on stream: Content-Type: text/event-stream, Cache-Control: no-cache, Connection: keep-alive, X-Accel-Buffering: no plus OLP diagnostic headers

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Audit method

Annual audit (target 2027-05-14): re-fetch each cited URL above, diff against the field lists above, file an ADR amendment for any newly-shipped OpenAI field or changed semantic that OLP should implement. Consult lib/ir/openai-to-ir.mjs and lib/ir/ir-to-openai.mjs as the implementation source of truth.

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Scope note: v0.1 baseline

This is a minimal baseline. v1.0+ should expand coverage to include the "NOT yet supported" fields above where OLP intends to support them (via openAIToIR amendments + ADR 0003 updates).