Crate ferrin_message 

Ferrin application-level messages.

• Message and its role structs: the conversation model applications build and persist. Content may be a plain string or a list of parts.
• Part types: UserPart, AssistantPart, ToolPart and the application-only parts ImagePart, FilePart, ReasoningFilePart, ToolApprovalRequest, ToolApprovalResponse. Parts whose shape equals the provider specification (TextPart, ReasoningPart, CustomPart, ToolCallPart, ToolResultPart, ToolResultOutput) are re-exported from ferrin_spec.
• FileSource: application file payloads (bytes, base64, URL, provider reference, inline text, local path) plus data_url parsing.
• prune: removal of reasoning, tool calls and empty messages from a history.

Conversion to the provider Prompt (downloads, media type detection) lives in the core crate.

Design: docs/01-architecture/03-core-data-model.md §7, docs/01-architecture/05-prompt-conversion.md.

Attribution

Portions of this crate are derived from the Vercel AI SDK (Apache-2.0, Copyright 2023 Vercel, Inc.), translated from TypeScript to Rust and modified. See the NOTICE file in the crate root.

Re-exports

pub use data_url::DataUrl;

pub use prune::PruneOptions;

Modules

data_url

RFC 2397 data: URL parsing.

prune

Message pruning: drop reasoning, tool calls and empty messages to control context size.

Structs

ApprovalId

Identifier of a tool approval request.

AssistantMessage

An assistant message.

CustomPart

Provider-specific content identified by a provider.type kind.

FilePart

A file in a user or assistant message.

ImagePart

An image in a user message.

InvalidDataContentError

Binary or data-URL content could not be decoded.

MediaType

An IANA media type such as image/png, or a top-level type such as image.

ReasoningFilePart

A reasoning artefact (for example an image the model reasoned over) in an assistant message.

ReasoningPart

Reasoning text produced by the model.

SystemMessage

A system message.

TextPart

Text content.

ToolApprovalRequest

A request for user approval of a tool call, recorded in an assistant message.

ToolApprovalResponse

The user’s answer to a ToolApprovalRequest, recorded in a tool message.

ToolCallId

Identifier of a tool call, assigned by the provider.

ToolCallPart

A tool call issued by the model in a previous step.

ToolMessage

A tool message.

ToolName

Name of a tool as exposed to the model.

ToolResultPart

The result of a tool call.

UserMessage

A user message.

Enums

AssistantContent

Content of an assistant message: a string or a list of parts.

AssistantPart

A part of an assistant message.

FileData

The payload of a file: inline bytes, a URL, a provider reference or an inline text document.

FileSource

Where the bytes of a file part come from.

FileSourceError

A FileSource could not be converted into provider file data.

Message

A message in an application conversation, tagged by role.

Role

The role of a Message.

ToolPart

A part of a tool message.

ToolResultContentPart

A part of a multi-part tool result.

ToolResultOutput

The output of a tool call as sent back to the model.

UserContent

Content of a user message: a string or a list of parts.

UserPart

A part of a user message.

Traits

MessagesExt

Helpers for message histories.

Type Aliases

ProviderOptions

Provider-specific request options, grouped by provider key.

ProviderReference

Provider-side resource identifiers, keyed by provider name.