Module a2a 

A2A discovery surface: the well-known catalog card and per-alias agent cards.

Structs

AgentCapabilities

A2A AgentCapabilities — optional feature flags. Only Some values serialize; None fields are omitted.

AgentCard

A2A AgentCard (spec §14) — the discovery surface for an agent. Serializes to the protobuf-JSON wire shape.

AgentInterface

A2A AgentInterface (spec §5.8) — a declared transport interface. The first entry of supportedInterfaces is the preferred transport. tenant, when set, MUST be echoed into the tenant field of every request sent to this interface (spec §5.2).

AgentSkill

A2A AgentSkill (spec §4.4). id/name/description are spec-required.

Artifact

A2A Artifact (proto message Artifact) — a task output. parts is the same Part oneof used by messages.

Message

A2A Message (proto message Message) — one unit of client/server communication. messageId and role are spec-REQUIRED on send, and parts MUST contain at least one Part (spec §5.7 REQUIRED — a list field with REQUIRED behavior must have ≥1 element).

Part

A2A Part (proto message Part) — a section of communication content. The content oneof is expressed without a discriminator: the active branch is exactly one of text / raw / url / data; the shared optional fields (metadata/filename/mediaType) ride alongside it. The oneof invariant is enforced at deserialization (via deserialize_part): a payload with zero content branches or more than one is rejected, matching the proto oneof semantics (spec §5.7 — a Part carries exactly one content branch). A struct (not an enum) lets serde handle the field-name-keyed shape directly while a custom deserializer validates the oneof invariant.

SendMessageParams

SendMessage request params (proto SendMessageRequest). tenant echoes the selected AgentInterface.tenant; message is REQUIRED.

Task

A2A Task (proto message Task) — returned by SendMessage / GetTask / CancelTask. Fields beyond the spec-required id/status are optional and tolerate absence: a peer that omits contextId or artifacts still parses.

TaskStatus

A2A TaskStatus (proto message TaskStatus).

Enums

Role

A2A Role (proto enum Role) — the sender of a message. ProtoJSON serializes enum values as their SCREAMING_SNAKE_CASE proto names (spec §5.5).

SendMessageResponse

SendMessageResponse (proto message SendMessageResponse) — the oneof payload with branches task / message. Custom de/serialization enforces exactly-one branch and the flat proto-shape ({"task": {...}} / {"message": {...}}): the default externally-tagged enum serializer would nest the branch value one level too deep ({"task":{"task":{...}}}) and would not round-trip through the custom deserializer.

TaskState

A2A TaskState (proto enum TaskState) — task lifecycle state. SCREAMING_SNAKE_CASE on the wire (spec §5.5). TASK_STATE_UNSPECIFIED is rejected at deserialization: the spec marks state as REQUIRED and the default UNSPECIFIED value must not be accepted as a valid wire value.

Functions

a2a_routes

a2a_task_route

build_agent_card

Build a spec-conforming per-alias agent card, or None when the alias is unknown or not published. Skills resolve from the alias’s bundles and narrow through exposed_skills.

build_catalog_card

Build the ZeroClaw discovery catalog card served at the origin root. Lists every published alias as a skill-less entry pointing at its per-alias card and endpoint. This is a catalog, not a runnable agent: it advertises the catalog interface and carries no skills of its own.