Class: PromptBuilder::Serializers::Messages::Request

Inherits:
Base
  • Object
show all
Defined in:
lib/prompt_builder/serializers/messages/request.rb

Overview

Request serializer for the Anthropic Messages API format.

Unsupported Open Responses features

These session fields are not supported and are silently omitted from the serialized output:

  • frequency_penalty — not supported by the Messages API
  • include — response-field inclusion is an Open Responses-only concept
  • max_tool_calls — per-request tool-call caps are not supported
  • presence_penalty — not supported by the Messages API
  • prompt_cache_key / prompt_cache_retention — explicit prompt cache keys are not supported
  • store — server-side response storage is not supported
  • stream_options — stream event options are not supported
  • top_logprobs — log probability output is not supported
  • truncation — server-side context truncation is not supported
  • background — background/async mode is not supported on the Messages endpoint
  • text.verbosity — Anthropic Messages has no equivalent verbosity control

Partially supported session fields (unsupported keys/values are omitted):

  • metadata — only the user_id key is forwarded; safety_identifier is also mapped into metadata.user_id automatically
  • service_tier — only auto and standard_only are accepted
  • text — format.type=json_schema is mapped to output_config.format
  • reasoning — budget_tokens, display, effort, and type are forwarded; temperature must be unset and top_p must be >= 0.95 when reasoning is enabled

Input content restrictions:

  • InputVideo content is not supported and is omitted
  • RefusalContent is dropped silently (a parsed refusal can stay in session history without breaking subsequent request_payload calls)
  • InputImage content is only supported in user messages (assistant images are omitted)
  • InputImage.detail is not part of the Anthropic schema and is dropped
  • InputImage.file_id is mapped to a file source (Anthropic Files API beta)
  • InputFile content is only supported in user messages (assistant files are omitted)
  • InputFile is sent as a document block; media_type is forwarded when provided, otherwise application/pdf is used for base64 sources
  • InputFile.file_id is mapped to a file source (Anthropic Files API beta)
  • Thinking blocks without a signature are dropped silently (cross-provider reasoning history doesn't round-trip into Anthropic)
  • Reasoning items with summary blocks have the summary dropped
  • Forced tool choice (+any+/+tool+ type) is incompatible with thinking enabled (raises)
  • Compaction and ItemReference items are silently skipped
  • FunctionCallOutput.status values incomplete, failed, and error are mapped to tool_result.is_error: true

Features in the Messages API not available through Open Responses

The following Messages API parameters cannot be set through the Open Responses canonical format:

  • top_k — top-K sampling parameter
  • stop_sequences — custom stop sequences
  • cache_control — top-level prompt-cache breakpoint selection
  • inference_geo — geographic inference routing
  • mcp_servers — MCP connector beta parameter
  • container — code execution container reuse parameter
  • cache_control markers on system blocks, message content blocks, tool definitions, or document blocks (prompt caching)
  • Citations on documents and tool_result content blocks
  • search_result content blocks
  • Web search, code execution, computer use, bash tool, text editor, and memory built-in tools
  • Redacted thinking round-trip (+redacted_thinking+ blocks are supported when they appear in conversation history but cannot be requested via OR)
  • Cryptographic thinking signatures (passed through in history but not configurable as a generation parameter)
  • anthropic-beta headers and API versioning (this gem produces no HTTP request — set headers in your HTTP client)

Constant Summary collapse

SUPPORTED_METADATA_KEYS = 
["user_id"].freeze
EFFORT_LEVELS = 
["low", "medium", "high", "xhigh", "max"].freeze
SUPPORTED_THINKING_TYPES = 
["adaptive", "disabled", "enabled"].freeze
SUPPORTED_TOOL_CHOICE_TYPES = 
["any", "auto", "none", "tool"].freeze
SUPPORTED_CITATION_TYPES =

Citation types accepted by the Messages API on text blocks. Annotations parsed from other providers (e.g. Chat Completions url_citation) have no Anthropic equivalent and are silently dropped.

[
  "char_location",
  "content_block_location",
  "page_location",
  "search_result_location",
  "web_search_result_location"
].freeze

Method Summary

Methods inherited from Base

parse_response, request_payload