---
title: internal/a2a
description: Go API reference for the a2a package.
---

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# a2a

```go
import "github.com/jbcom/radioactive-ralph/internal/a2a"
```

Package a2a is a thin adoption layer over github.com/a2aproject/a2a\-go/v2's core vocabulary \(github.com/a2aproject/a2a\-go/v2/a2a\), per .agent\-state/decisions.ndjson \("a2a\-comms\-layer"\) and spec §12.

We import ONLY the a2a\-go core\-types package \(a2a/\), which is stdlib\-only \(plus github.com/google/uuid\) — never a2asrv/a2agrpc/a2apb, which pull in grpc/protobuf. This package re\-exports the TaskState constants radioactive \-ralph actually uses, and defines Evidence: the structured result a worker submits to the orchestrator, carried as an a2a.Message so worker\<\-\> orchestrator communication uses the standard vocabulary.

The a2a\_messages store table \(see internal/store/schema/0002\_a2a.up.sql\) is a message/evidence LOG, not a parallel task store — the store's existing tasks table is the durable DAG \(§ decision "a2a\-comms\-layer": "Don't create a parallel task store — the plan DAG IS the task store"\).

Critically: nothing in this package marks a task done. A worker submitting Evidence via an a2a.Message is a proposal for the orchestrator to verify \(see internal/orch.VerifyAndComplete\) — never a self\-assertion of completion.

## Index

- [Constants](<#constants>)
- [func MarshalEvidence\(ev Evidence\) \(string, error\)](<#MarshalEvidence>)
- [type Evidence](<#Evidence>)
  - [func EvidenceFromMessage\(msg \*Message\) \(Evidence, error\)](<#EvidenceFromMessage>)
  - [func UnmarshalEvidence\(raw string\) \(Evidence, error\)](<#UnmarshalEvidence>)
- [type Message](<#Message>)
  - [func NewEvidenceMessage\(role a2a.MessageRole, taskID, contextID string, ev Evidence\) \*Message](<#NewEvidenceMessage>)
- [type Part](<#Part>)
- [type TaskState](<#TaskState>)


## Constants

<a name="StateSubmitted"></a>The TaskState values radioactive\-ralph uses to describe a worker's progress against one store task. The orchestrator drives these transitions; a worker only ever SUGGESTS one via submitted Evidence.

```go
const (
    // StateSubmitted: the task has been claimed and dispatched to a worker
    // but the worker has not yet reported evidence.
    StateSubmitted = a2a.TaskStateSubmitted
    // StateWorking: the worker is actively executing.
    StateWorking = a2a.TaskStateWorking
    // StateInputRequired is the never-block signal: a worker that would
    // otherwise block waiting for input is in this TASK STATE, which the
    // orchestrator handles by re-dispatching with an answer or by
    // kill+reclaim — never by waiting on a blocked pty.
    StateInputRequired = a2a.TaskStateInputRequired
    // StateCompleted: ORCHESTRATOR-VERIFIED completion only. Never set
    // directly from a worker's self-report or from process termination.
    StateCompleted = a2a.TaskStateCompleted
    // StateFailed: verification rejected the evidence, or the worker
    // reported failure.
    StateFailed = a2a.TaskStateFailed
)
```

<a name="RoleAgent"></a>Role constants used when constructing evidence messages.

```go
const (
    RoleAgent = a2a.MessageRoleAgent
    RoleUser  = a2a.MessageRoleUser
)
```

<a name="MarshalEvidence"></a>
## func [MarshalEvidence](<https://github.com/jbcom/radioactive-ralph/blob/main/internal/a2a/a2a.go#L107>)

```go
func MarshalEvidence(ev Evidence) (string, error)
```

MarshalEvidence serializes Evidence to a JSON string for storage in the store's evidence/payload columns \(e.g. MarkDone's evidenceJSON parameter\).

<a name="Evidence"></a>
## type [Evidence](<https://github.com/jbcom/radioactive-ralph/blob/main/internal/a2a/a2a.go#L72-L92>)

Evidence is what a worker submits after it believes it has completed a task: what it ran, what happened, and what changed. This is a PROPOSAL — the orchestrator's VerifyAndComplete re\-checks it against the task's acceptance criteria before ever marking the task done in the store.

```go
type Evidence struct {
    // Ran is the mechanical check the worker believes satisfies the task's
    // acceptance criterion (e.g. "go test ./..." or a file path). Advisory
    // only — the orchestrator re-runs the real check itself rather than
    // trusting this string.
    Ran string `json:"ran,omitempty"`

    // ExitCode is the exit status the worker observed when it ran Ran, if
    // applicable. Advisory only, same caveat as Ran.
    ExitCode int `json:"exit_code"`

    // Output is a bounded capture of what Ran produced (stdout/stderr),
    // kept for the audit trail and for judgment-based acceptance criteria.
    Output string `json:"output,omitempty"`

    // Diff is the worker's summary/patch of what it changed, if any.
    Diff string `json:"diff,omitempty"`

    // FilesChanged lists paths the worker believes it modified.
    FilesChanged []string `json:"files_changed,omitempty"`
}
```

<a name="EvidenceFromMessage"></a>
### func [EvidenceFromMessage](<https://github.com/jbcom/radioactive-ralph/blob/main/internal/a2a/a2a.go#L131>)

```go
func EvidenceFromMessage(msg *Message) (Evidence, error)
```

EvidenceFromMessage extracts Evidence from an a2a.Message's first Data part. Returns an error if the message carries no data part.

<a name="UnmarshalEvidence"></a>
### func [UnmarshalEvidence](<https://github.com/jbcom/radioactive-ralph/blob/main/internal/a2a/a2a.go#L118>)

```go
func UnmarshalEvidence(raw string) (Evidence, error)
```

UnmarshalEvidence parses a JSON string back into Evidence. Used when reloading a worker's submitted evidence \(e.g. from an a2a\_messages row or a stored event payload\) for \(re\-\)verification.

<a name="Message"></a>
## type [Message](<https://github.com/jbcom/radioactive-ralph/blob/main/internal/a2a/a2a.go#L57>)

Message re\-exports a2a.Message, the core type used to carry Evidence.

```go
type Message = a2a.Message
```

<a name="NewEvidenceMessage"></a>
### func [NewEvidenceMessage](<https://github.com/jbcom/radioactive-ralph/blob/main/internal/a2a/a2a.go#L97>)

```go
func NewEvidenceMessage(role a2a.MessageRole, taskID, contextID string, ev Evidence) *Message
```

NewEvidenceMessage wraps Evidence as an a2a.Message with a single JSON data Part, tagged with the given plan/task context. role is typically RoleAgent \(a worker reporting evidence to the orchestrator\).

<a name="Part"></a>
## type [Part](<https://github.com/jbcom/radioactive-ralph/blob/main/internal/a2a/a2a.go#L60>)

Part re\-exports a2a.Part, one content part of a Message.

```go
type Part = a2a.Part
```

<a name="TaskState"></a>
## type [TaskState](<https://github.com/jbcom/radioactive-ralph/blob/main/internal/a2a/a2a.go#L32>)

TaskState re\-exports a2a.TaskState so callers need not import the upstream package directly for the states radioactive\-ralph drives.

```go
type TaskState = a2a.TaskState
```

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