Request
The payload of the channel request the server sends: the tag byte 9 and the ask.
[9][params JSON …]- The params. The params of the exchange as JSON, relayed verbatim.
The channel request is defined by diverge-sdk-rs/src/provider/endpoints/containers/agents/run/server/channel_request/frame.rs:
//! What a server's channel request frame carries for an agent container
//! run.
use std::fmt;
use crate::wire::decode::Decode;
use crate::wire::encode::{Encode, Writer};
use crate::shared::containers::{fuse, oci, postgres, registration, write_bytes};
use crate::shared::mcp;
/// What a provider asks a caller for while an agent container runs.
///
/// A payload leads with one byte saying which, and the rest is that
/// variant's own bytes.
///
/// | tag | asks for |
/// |-----|----------|
/// | `0` | [`OciManifest`](Self::OciManifest) |
/// | `1` | [`OciBlob`](Self::OciBlob) |
/// | `2` | [`OciHas`](Self::OciHas) |
/// | `3` | [`Registration`](Self::Registration) |
/// | `4` | [`Write`](Self::Write) |
/// | `5` | [`Postgres`](Self::Postgres) |
/// | `6` | [`McpListTools`](Self::McpListTools) |
/// | `7` | [`McpListResources`](Self::McpListResources) |
/// | `8` | [`McpCallTool`](Self::McpCallTool) |
/// | `9` | [`McpReadResource`](Self::McpReadResource) |
/// | `10` | [`McpNotifications`](Self::McpNotifications) |
/// | `11` | [`FuseRead`](Self::FuseRead) |
/// | `12` | [`FuseWrite`](Self::FuseWrite) |
/// | `13` | [`FuseList`](Self::FuseList) |
/// | `14` | [`FuseRemove`](Self::FuseRemove) |
/// | `15` | [`FuseRename`](Self::FuseRename) |
/// | `16` | [`FuseMkdir`](Self::FuseMkdir) |
/// | `17` | [`FuseStat`](Self::FuseStat) |
/// | `18` | [`FuseTruncate`](Self::FuseTruncate) |
/// | `19` | [`FuseSetattr`](Self::FuseSetattr) |
///
/// Twenty. The first five are the provider's own asks — whether the
/// caller holds an image, its manifest and blobs, the container's
/// registration, a write's content — and the rest are the
/// CONTAINER's, relayed: its database connections, its tool calls
/// outward to the caller's MCP servers, and the files the caller
/// mounted live. No daemon connection: an agent
/// container holds no account and asks the daemon nothing, and only
/// a tool container asks the caller for one.
#[derive(Debug, Clone, PartialEq)]
pub enum Frame<'a> {
/// A manifest of an image the caller holds, by digest. Tag `0`.
///
/// Opened when the provider takes the image from the caller, and
/// opened by the container RUNTIME's appetite rather
/// than the provider's: the provider's registry serves the pull,
/// and a manifest its store does not hold becomes one of these.
/// See [`oci`](crate::shared::containers::oci).
OciManifest(oci::manifest::request::Request),
/// A blob of an image the caller holds, by digest. Tag `1`.
///
/// The other half of a pull; see
/// [`oci`](crate::shared::containers::oci).
OciBlob(oci::blob::request::Request),
/// Whether the caller holds an image, by digest, and under what
/// name. Tag `2`.
///
/// Opened by a provider that would take the image from the caller,
/// before it asks for anything of it; see
/// [`oci`](crate::shared::containers::oci).
OciHas(oci::has::request::Request),
/// Register the container: deploy the dependencies it declared,
/// and resolve the secrets it takes. Tag `3`.
///
/// Opened once, after the proxy's `Begun` carried a non-empty
/// list or a non-empty declaration, and before the id; answered
/// with the secrets' first values, which the provider feeds to
/// the container before it sends the id. See
/// [`registration`](crate::shared::containers::registration).
Registration(registration::request::Request<'a>),
/// Send the content for a write. Tag `4`.
///
/// Opened in answer to a write the caller started. A write cannot
/// carry its own content — only a responder can finish a channel —
/// so the bytes travel as responses on this one. See
/// [`write_bytes`](crate::shared::containers::write_bytes).
Write(write_bytes::request::Request),
/// The provider's half of a database connection the container
/// opened. Tag `5`.
///
/// What comes back is everything the database says; the caller
/// opens the other half, or declines. See
/// [`postgres`](crate::shared::containers::postgres).
Postgres(postgres::request::Postgres),
/// What tools the caller's servers have. Tag `6`.
///
/// The container asking OUTWARD: an agent's tool calls go to
/// servers that live with the caller, so the five exchanges in
/// [`shared::mcp`](crate::shared::mcp) travel this direction too.
McpListTools(mcp::list_tools::request::Request),
/// What resources they have. Tag `7`.
McpListResources(mcp::list_resources::request::Request),
/// Run one of their tools. Tag `8`.
McpCallTool(mcp::call_tool::request::Request),
/// Read one of their resources. Tag `9`.
McpReadResource(mcp::read_resource::request::Request),
/// Everything they say on their own account. Tag `10`.
McpNotifications(mcp::notifications::request::Request),
/// Read a piece of a file the caller mounted live, by the mount's
/// id, the file's path in it, an offset and a length. Tag `11`.
///
/// The container's proxy asking on behalf of a FUSE mount: every
/// `read(2)` of the file. See
/// [`fuse`](crate::shared::containers::fuse).
FuseRead(fuse::read::request::Request<'a>),
/// Write a piece of a file the caller mounted live, in place at
/// an offset. Tag `12`.
///
/// Every `write(2)` of the file.
FuseWrite(fuse::write::request::Request<'a>),
/// List a directory of a tree the caller mounted live. Tag `13`.
///
/// Every listing in a directory mount: names and kinds.
FuseList(fuse::list::request::Request<'a>),
/// Remove a file or an empty directory of such a tree. Tag `14`.
FuseRemove(fuse::remove::request::Request<'a>),
/// Rename an entry within such a tree. Tag `15`.
FuseRename(fuse::rename::request::Request<'a>),
/// Make a directory in such a tree. Tag `16`.
FuseMkdir(fuse::mkdir::request::Request<'a>),
/// What an entry the caller mounted live is: kind, size, mode,
/// owner, group and times. Tag `17`.
///
/// Every attribute of a file mount, and every lookup and
/// attribute of an entry in a directory mount: a `stat` costs
/// fifty-seven bytes back, not the file.
FuseStat(fuse::stat::request::Request<'a>),
/// Set a file the caller mounted live to a length. Tag `18`.
///
/// Every `truncate(2)`, `ftruncate(2)` and `O_TRUNC` open.
FuseTruncate(fuse::truncate::request::Request<'a>),
/// Set some attributes of an entry the caller mounted live. Tag
/// `19`.
///
/// Every `chmod(2)`, `chown(2)` and `utimensat(2)`.
FuseSetattr(fuse::setattr::request::Request<'a>),
}
/// Tag for [`Frame::OciManifest`].
const OCI_MANIFEST: u8 = 0;
/// Tag for [`Frame::OciBlob`].
const OCI_BLOB: u8 = 1;
/// Tag for [`Frame::OciHas`].
const OCI_HAS: u8 = 2;
/// Tag for [`Frame::Registration`].
const REGISTRATION: u8 = 3;
/// Tag for [`Frame::Write`].
const WRITE: u8 = 4;
/// Tag for [`Frame::Postgres`].
const POSTGRES: u8 = 5;
/// Tag for [`Frame::McpListTools`].
const MCP_LIST_TOOLS: u8 = 6;
/// Tag for [`Frame::McpListResources`].
const MCP_LIST_RESOURCES: u8 = 7;
/// Tag for [`Frame::McpCallTool`].
const MCP_CALL_TOOL: u8 = 8;
/// Tag for [`Frame::McpReadResource`].
const MCP_READ_RESOURCE: u8 = 9;
/// Tag for [`Frame::McpNotifications`].
const MCP_NOTIFICATIONS: u8 = 10;
/// Tag for [`Frame::FuseRead`].
const FUSE_READ: u8 = 11;
/// Tag for [`Frame::FuseWrite`].
const FUSE_WRITE: u8 = 12;
/// Tag for [`Frame::FuseList`].
const FUSE_LIST: u8 = 13;
/// Tag for [`Frame::FuseRemove`].
const FUSE_REMOVE: u8 = 14;
/// Tag for [`Frame::FuseRename`].
const FUSE_RENAME: u8 = 15;
/// Tag for [`Frame::FuseMkdir`].
const FUSE_MKDIR: u8 = 16;
/// Tag for [`Frame::FuseStat`].
const FUSE_STAT: u8 = 17;
/// Tag for [`Frame::FuseTruncate`].
const FUSE_TRUNCATE: u8 = 18;
/// Tag for [`Frame::FuseSetattr`].
const FUSE_SETATTR: u8 = 19;
impl Encode for Frame<'_> {
/// The JSON failure from the asks that are JSON, or a fuse id or
/// path too long for its prefix; everything else is bytes copied.
type Error = FrameEncodeError;
fn encode(&self, out: &mut Writer<'_>) -> Result<(), FrameEncodeError> {
match self {
Frame::OciManifest(request) => {
out.extend_from_slice(&[OCI_MANIFEST]);
request.encode(out).map_err(FrameEncodeError::Json)
}
Frame::OciBlob(request) => {
out.extend_from_slice(&[OCI_BLOB]);
request.encode(out).map_err(FrameEncodeError::Json)
}
Frame::OciHas(request) => {
out.extend_from_slice(&[OCI_HAS]);
request.encode(out).map_err(FrameEncodeError::Json)
}
Frame::Registration(request) => {
out.extend_from_slice(&[REGISTRATION]);
request.encode(out).map_err(FrameEncodeError::Json)
}
Frame::Write(request) => {
out.extend_from_slice(&[WRITE]);
// Its error is `Infallible`, and an empty match on one
// is how you say so: there is no value to handle.
request.encode(out).map_err(|error| match error {})
}
Frame::Postgres(request) => {
out.extend_from_slice(&[POSTGRES]);
request.encode(out).map_err(|error| match error {})
}
Frame::McpListTools(request) => {
out.extend_from_slice(&[MCP_LIST_TOOLS]);
request.encode(out).map_err(FrameEncodeError::Json)
}
Frame::McpListResources(request) => {
out.extend_from_slice(&[MCP_LIST_RESOURCES]);
request.encode(out).map_err(FrameEncodeError::Json)
}
Frame::McpCallTool(request) => {
out.extend_from_slice(&[MCP_CALL_TOOL]);
request.encode(out).map_err(FrameEncodeError::Json)
}
Frame::McpReadResource(request) => {
out.extend_from_slice(&[MCP_READ_RESOURCE]);
request.encode(out).map_err(FrameEncodeError::Json)
}
Frame::McpNotifications(request) => {
out.extend_from_slice(&[MCP_NOTIFICATIONS]);
request.encode(out).map_err(|error| match error {})
}
Frame::FuseRead(request) => {
out.extend_from_slice(&[FUSE_READ]);
request.encode(out).map_err(FrameEncodeError::Fuse)
}
Frame::FuseWrite(request) => {
out.extend_from_slice(&[FUSE_WRITE]);
request.encode(out).map_err(FrameEncodeError::Fuse)
}
Frame::FuseList(request) => {
out.extend_from_slice(&[FUSE_LIST]);
request.encode(out).map_err(FrameEncodeError::Fuse)
}
Frame::FuseRemove(request) => {
out.extend_from_slice(&[FUSE_REMOVE]);
request.encode(out).map_err(FrameEncodeError::Fuse)
}
Frame::FuseRename(request) => {
out.extend_from_slice(&[FUSE_RENAME]);
request.encode(out).map_err(FrameEncodeError::Fuse)
}
Frame::FuseMkdir(request) => {
out.extend_from_slice(&[FUSE_MKDIR]);
request.encode(out).map_err(FrameEncodeError::Fuse)
}
Frame::FuseStat(request) => {
out.extend_from_slice(&[FUSE_STAT]);
request.encode(out).map_err(FrameEncodeError::Fuse)
}
Frame::FuseTruncate(request) => {
out.extend_from_slice(&[FUSE_TRUNCATE]);
request.encode(out).map_err(FrameEncodeError::Fuse)
}
Frame::FuseSetattr(request) => {
out.extend_from_slice(&[FUSE_SETATTR]);
request.encode(out).map_err(FrameEncodeError::Fuse)
}
}
}
}
/// An agent container run channel request that could not be written.
#[derive(Debug)]
pub enum FrameEncodeError {
/// A JSON ask did not serialize.
Json(serde_json::Error),
/// A fuse ask would not encode: an id or a path too long for its
/// prefix.
Fuse(fuse::RequestEncodeError),
}
impl fmt::Display for FrameEncodeError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
FrameEncodeError::Json(error) => {
write!(f, "channel request did not serialize: {error}")
}
FrameEncodeError::Fuse(error) => write!(f, "{error}"),
}
}
}
impl std::error::Error for FrameEncodeError {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
match self {
FrameEncodeError::Json(error) => Some(error),
FrameEncodeError::Fuse(error) => Some(error),
}
}
}
impl<'a> Decode<'a> for Frame<'a> {
/// Several ways to fail, and each names which ask it was.
type Error = FrameError;
fn decode(bytes: &'a [u8]) -> Result<Self, Self::Error> {
let (tag, rest) = bytes.split_first().ok_or(FrameError::Empty)?;
match *tag {
OCI_MANIFEST => oci::manifest::request::Request::decode(rest)
.map(Frame::OciManifest)
.map_err(FrameError::Oci),
OCI_BLOB => oci::blob::request::Request::decode(rest)
.map(Frame::OciBlob)
.map_err(FrameError::Oci),
OCI_HAS => oci::has::request::Request::decode(rest)
.map(Frame::OciHas)
.map_err(FrameError::Oci),
REGISTRATION => registration::request::Request::decode(rest)
.map(Frame::Registration)
.map_err(FrameError::Registration),
WRITE => write_bytes::request::Request::decode(rest)
.map(Frame::Write)
.map_err(FrameError::Write),
POSTGRES => postgres::request::Postgres::decode(rest)
.map(Frame::Postgres)
.map_err(FrameError::Postgres),
MCP_LIST_TOOLS => mcp::list_tools::request::Request::decode(rest)
.map(Frame::McpListTools)
.map_err(FrameError::McpParams),
MCP_LIST_RESOURCES => {
mcp::list_resources::request::Request::decode(rest)
.map(Frame::McpListResources)
.map_err(FrameError::McpParams)
}
MCP_CALL_TOOL => mcp::call_tool::request::Request::decode(rest)
.map(Frame::McpCallTool)
.map_err(FrameError::McpParams),
MCP_READ_RESOURCE => {
mcp::read_resource::request::Request::decode(rest)
.map(Frame::McpReadResource)
.map_err(FrameError::McpParams)
}
MCP_NOTIFICATIONS => Ok(Frame::McpNotifications(
mcp::notifications::request::Request::decode(rest)
.unwrap_or_else(|error| match error {}),
)),
FUSE_READ => fuse::read::request::Request::decode(rest)
.map(Frame::FuseRead)
.map_err(FrameError::Fuse),
FUSE_WRITE => fuse::write::request::Request::decode(rest)
.map(Frame::FuseWrite)
.map_err(FrameError::Fuse),
FUSE_LIST => fuse::list::request::Request::decode(rest)
.map(Frame::FuseList)
.map_err(FrameError::Fuse),
FUSE_REMOVE => fuse::remove::request::Request::decode(rest)
.map(Frame::FuseRemove)
.map_err(FrameError::Fuse),
FUSE_RENAME => fuse::rename::request::Request::decode(rest)
.map(Frame::FuseRename)
.map_err(FrameError::Fuse),
FUSE_MKDIR => fuse::mkdir::request::Request::decode(rest)
.map(Frame::FuseMkdir)
.map_err(FrameError::Fuse),
FUSE_STAT => fuse::stat::request::Request::decode(rest)
.map(Frame::FuseStat)
.map_err(FrameError::Fuse),
FUSE_TRUNCATE => fuse::truncate::request::Request::decode(rest)
.map(Frame::FuseTruncate)
.map_err(FrameError::Fuse),
FUSE_SETATTR => fuse::setattr::request::Request::decode(rest)
.map(Frame::FuseSetattr)
.map_err(FrameError::Fuse),
tag => Err(FrameError::UnknownTag(tag)),
}
}
}
/// An agent container run channel request that could not be read.
#[derive(Debug)]
pub enum FrameError {
/// No bytes at all, so not even a tag.
Empty,
/// A tag that is none of this frame's twenty.
UnknownTag(u8),
/// An image ask did not parse.
Oci(serde_json::Error),
/// The registration did not parse.
Registration(serde_json::Error),
/// The write content request did not decode.
Write(write_bytes::request::RequestError),
/// The connection id was not four bytes.
Postgres(postgres::request::PostgresError),
/// A fuse ask did not decode.
Fuse(fuse::RequestError),
/// One of the five MCP exchanges' params did not parse.
///
/// One variant for five tags, because they fail the same way and
/// the tag already said which was meant.
McpParams(serde_json::Error),
}
impl fmt::Display for FrameError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
FrameError::Empty => {
f.write_str("agents run channel request frame is empty")
}
FrameError::UnknownTag(tag) => {
write!(f, "unknown agents run channel request tag {tag}")
}
FrameError::Oci(error) => {
write!(f, "image ask did not parse: {error}")
}
FrameError::Registration(error) => {
write!(f, "registration did not parse: {error}")
}
FrameError::Write(error) => {
write!(f, "write content request did not decode: {error}")
}
FrameError::Postgres(error) => write!(f, "{error}"),
FrameError::Fuse(error) => write!(f, "{error}"),
FrameError::McpParams(error) => {
write!(f, "mcp request params did not parse: {error}")
}
}
}
}
impl std::error::Error for FrameError {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
match self {
FrameError::Oci(error)
| FrameError::Registration(error)
| FrameError::McpParams(error) => Some(error),
FrameError::Write(error) => Some(error),
FrameError::Postgres(error) => Some(error),
FrameError::Fuse(error) => Some(error),
FrameError::Empty | FrameError::UnknownTag(_) => None,
}
}
}and by diverge-sdk-rs/src/shared/mcp/read_resource/request/request.rs:
//! Asking for a resource to be read.
use rmcp::model::{ReadResourceRequestParams};
use serde_json::Error;
use crate::wire::decode::Decode;
use crate::wire::encode::{Encode, Writer};
/// The URI of a resource.
///
/// The URI is the server's to interpret. A relay that resolved one
/// would be deciding what a resource is.
///
/// # It is a wrapper, and a thin one
///
/// [`rmcp`] already defines the shape and this crate has no business
/// redefining it — an MCP request has one form and it is MCP's. What
/// the wrapper adds is the two impls beneath it, so that a channel
/// request carrying one writes `request.encode(out)` like every other
/// payload in this crate rather than reaching for `serde_json` itself.
#[derive(Debug, Clone, PartialEq)]
pub struct Request(
/// The parameters, as [`rmcp`] defines them.
pub ReadResourceRequestParams,
);
/// Its JSON, and nothing in front of it. The tag that says which
/// request this is belongs to whichever frame carries it.
impl Encode for Request {
/// The ordinary JSON failure.
type Error = Error;
fn encode(&self, out: &mut Writer<'_>) -> Result<(), Error> {
serde_json::to_writer(out, &self.0)
}
}
impl Decode<'_> for Request {
/// The ordinary JSON failure. There is nothing else here to get
/// wrong — no tag to be unknown, and no empty case, since no bytes
/// at all is a JSON document that ended too early and is reported
/// as one.
type Error = Error;
fn decode(bytes: &[u8]) -> Result<Self, Error> {
serde_json::from_slice(bytes).map(Request)
}
}