# `Raxol.AgentClientProtocol.Schema.Version`
[🔗](https://github.com/DROOdotFOO/raxol-agent/blob/raxol_agent_client_protocol-v0.1.0/packages/raxol_agent_client_protocol/lib/raxol/agent_client_protocol/schema/version.ex#L1)

Protocol version identifier for ACP (`protocolVersion` on the wire).

Only bumped for breaking changes to the protocol surface. The wire value
is a plain integer (`1` is the current stable ACP v1 surface) — never a
semver string.

## Legacy date-string handshakes

Some ACP-adjacent clients (notably Zed, in older releases) sent a
date-formatted `protocolVersion` inherited from MCP's `"2024-11-05"`-style
versioning instead of ACP's integer scheme. `from_json/1` is strict and
rejects that shape; `coerce/1` is the tolerant counterpart that accepts it
(and any other legacy string) by mapping it to `latest/0`, so a handshake
from an older/foreign client degrades gracefully instead of failing the
connection outright. Callers doing the initial `initialize` handshake
should prefer `coerce/1`; callers validating an already-negotiated,
spec-conformant value should use the stricter `from_json/1`.

Ported from the MIT `f1729/agent_client_protocol` (c) 2025 f1729; see NOTICE.md.

# `t`

```elixir
@type t() :: non_neg_integer()
```

# `coerce`

```elixir
@spec coerce(term()) :: {:ok, t()} | {:error, :invalid_protocol_version}
```

Tolerant deserialize for `protocolVersion`, for handshakes with clients
that may not speak the current integer scheme.

Non-negative integers pass through unchanged. Any string (including a
legacy MCP-style date string such as `"2024-11-05"`) is coerced to
`latest/0` rather than rejected. This is deliberately lenient: we don't attempt to
parse or validate the string's shape, we simply treat "sent a string at
all" as "speaks a version we don't recognize, negotiate down to what we
know". Anything else is rejected. Never raises.

# `from_json`

```elixir
@spec from_json(term()) :: {:ok, t()} | {:error, :invalid_protocol_version}
```

Deserialize `protocolVersion` from an already-decoded JSON value.

Strict: only non-negative integers are accepted. Never raises — always
returns a result tuple, even for malformed input.

# `latest`

```elixir
@spec latest() :: t()
```

The latest protocol version this library implements.

# `v0`

```elixir
@spec v0() :: t()
```

The initial (pre-stabilization) protocol version.

# `v1`

```elixir
@spec v1() :: t()
```

The current stable ACP v1 protocol version.

---

*Consult [api-reference.md](api-reference.md) for complete listing*