Module types 

Pi session schema (format version 3).

Pi is a terminal coding agent that stores sessions as JSONL files. The first line is a SessionHeader; every subsequent line is an Entry, forming a tree via id / parentId.

All structs carry an extra catch-all to preserve unknown fields for forward compatibility.

Structs

CostBreakdown

Dollar cost breakdown accompanying Usage.

EntryBase

Shared fields on every non-header entry.

SessionHeader

Pi session file header (first line of a .jsonl file).

ToolCall

A tool-use request inside an assistant content block.

Usage

Per-turn token accounting.

Enums

AgentMessage

A message inside a message entry. Role-tagged union.

ContentBlock

One element of a message’s content array.

Entry

A single entry in a Pi session JSONL.

KnownStopReason

Enumerated stop reasons defined by Pi. Kept inside StopReason so that unknown strings (e.g. from future Pi versions) still deserialize.

MessageContent

Content field for user / custom-role messages: either a bare string or a list of content blocks.

StopReason

Assistant stop reason. Unknown values round-trip through StopReason::Other.

ToolResultContent

Restricted content block set for toolResult messages. Per the Pi schema, tool results may only carry text or image content.