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Take MCP servers from pebble

Browse source 
Step 3 of .ai/plans/pebble-absorbs-embedder-concerns.md, pinning pebble
6cdb30a with its `mcp` feature.

Pebble starts the stage's MCP servers while the agent is built, registers
their tools under `mcp__{server}__{tool}` with `ToolSource::Mcp`, and
closes them with the agent, for all three placements: a child of the run
worker over stdio, a server over HTTP (streamable or SSE), and a server
launched in the run sandbox and reached through the sandbox's preview
URL. `fabro_mcp::pebble::pebble_server` maps `McpServerSettings` onto
pebble's `McpServer`, keeping fabro's `/sse` path for sandbox-hosted SSE
servers; `RunSandbox::port_routes` hands pebble the driver's `PreviewUrls`
facet as the route to a sandbox port. The stage's event sink mirrors
`McpServerReady` and `McpServerFailed` onto the run's `agent.mcp.ready`
and `agent.mcp.failed` events, as it mirrors `RouteFailover` onto
`agent.failover`, and stores no second copy of a mirrored fact.

Deleted: `sandbox_mcp.rs`, the MCP branches of `pebble.rs` and `fabro
exec`, and fabro-mcp's client, connection manager, HTTP helpers, and SSE
transport, whose tests moved to pebble. fabro-mcp keeps the settings
re-export, the mapping, and a stdio client behind `test-support` for the
tests of fabro's own MCP server. `fabro exec` reports each server's
outcome from the agent's snapshot. The Daytona Playwright live test now
drives the sandbox-hosted server through an agent.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
This commit is contained in:
Bryan Helmkamp 2026-09-11 19:26:41 -06:00
parent b5fd907c3d
commit 64c578d044
No known key found for this signature in database
22 changed files with 686 additions and 2332 deletions
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23
Cargo.lock generated
View file

@ -2774,19 +2774,11 @@ name = "fabro-mcp"
version = "0.348.0-nightly.0"
dependencies = [
"anyhow",
"axum",
"fabro-config",
"fabro-http",
"fabro-types",
"futures",
"pebble-coding-agent",
"rmcp",
"serde",
"serde_json",
"sse-stream",
"thiserror 2.0.18",
"tokio",
"tokio-stream",
"tracing",
]
@ -4353,7 +4345,7 @@ dependencies = [
"js-sys",
"log",
"wasm-bindgen",
"windows-core 0.61.2",
"windows-core 0.62.2",
]
[[package]]
@ -5864,7 +5856,7 @@ dependencies = [
[[package]]
name = "pebble-agent"
version = "0.1.0"
source = "git+https://github.com/lithoscomputer/pebble?rev=1a5abe4a83b3c13f8ecbb38f761d17ede8e3d7d5#1a5abe4a83b3c13f8ecbb38f761d17ede8e3d7d5"
source = "git+https://github.com/lithoscomputer/pebble?rev=6cdb30a874010582106bbde80ac91ae000dc13d8#6cdb30a874010582106bbde80ac91ae000dc13d8"
dependencies = [
"async-trait",
"futures-util",
@ -5881,20 +5873,25 @@ dependencies = [
[[package]]
name = "pebble-coding-agent"
version = "0.1.0"
source = "git+https://github.com/lithoscomputer/pebble?rev=1a5abe4a83b3c13f8ecbb38f761d17ede8e3d7d5#1a5abe4a83b3c13f8ecbb38f761d17ede8e3d7d5"
source = "git+https://github.com/lithoscomputer/pebble?rev=6cdb30a874010582106bbde80ac91ae000dc13d8#6cdb30a874010582106bbde80ac91ae000dc13d8"
dependencies = [
"async-trait",
"futures-util",
"lithos-llm",
"pebble-agent",
"reqwest 0.13.4",
"rmcp",
"rustix",
"sandbox-driver",
"serde",
"serde_json",
"sha2 0.10.9",
"sse-stream",
"thiserror 2.0.18",
"tokio",
"tokio-util",
"tracing",
"url",
"uuid",
]
@ -7748,9 +7745,9 @@ dependencies = [
[[package]]
name = "sse-stream"
version = "0.2.1"
version = "0.2.6"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "eb4dc4d33c68ec1f27d386b5610a351922656e1fdf5c05bbaad930cd1519479a"
checksum = "c25ac7aff0abd1dbc474536e40416e1102c7dd9bfba0b9861c6d357f835dcfb4"
dependencies = [
"bytes",
"futures-util",

5
Cargo.toml
View file

@ -27,7 +27,6 @@ serde_json = { version = "1", features = ["preserve_order"] }
sqlx = { version = "0.9", default-features = false, features = ["runtime-tokio", "sqlite-bundled", "migrate", "macros"] }
tokio = { version = "1", features = ["full"] }
reqwest = { version = "0.13", default-features = false, features = ["json", "stream", "rustls", "query", "form", "multipart"] }
sse-stream = "0.2"
ulid = "1"
uuid = { version = "1", features = ["v4", "v7", "v8"] }
rand = "0.9"
@ -113,8 +112,8 @@ futures-util = "0.3"
# the merge commit once it lands. Pebble pins the same lithos-llm rev as
# fabro, and its lockfile policy is that every shared crate resolves to the
# version lithos-llm locks.
pebble-agent = { git = "https://github.com/lithoscomputer/pebble", rev = "1a5abe4a83b3c13f8ecbb38f761d17ede8e3d7d5" }
pebble-coding-agent = { git = "https://github.com/lithoscomputer/pebble", rev = "1a5abe4a83b3c13f8ecbb38f761d17ede8e3d7d5" }
pebble-agent = { git = "https://github.com/lithoscomputer/pebble", rev = "6cdb30a874010582106bbde80ac91ae000dc13d8" }
pebble-coding-agent = { git = "https://github.com/lithoscomputer/pebble", rev = "6cdb30a874010582106bbde80ac91ae000dc13d8", features = ["mcp"] }
sandbox-driver = { git = "https://github.com/lithoscomputer/sandbox-driver", rev = "23062b6ad62ff4665cbbcb7dce037ec9c4c34318" }
sandbox-driver-protocol = { git = "https://github.com/lithoscomputer/sandbox-driver", rev = "23062b6ad62ff4665cbbcb7dce037ec9c4c34318" }
sandbox-driver-host = { git = "https://github.com/lithoscomputer/sandbox-driver", rev = "23062b6ad62ff4665cbbcb7dce037ec9c4c34318" }

1
lib/apps/fabro-cli/Cargo.toml
View file

@ -117,6 +117,7 @@ chrono = { workspace = true }
[dev-dependencies]
assert_cmd = "2"
fabro-acp = { path = "../../components/fabro-acp", features = ["test-support"] }
fabro-mcp = { path = "../../components/fabro-mcp", features = ["test-support"] }
fabro-build-support = { path = "../../foundation/build-support" }
fabro-server = { path = "../fabro-server", features = ["test-support"] }
fabro-workflow = { path = "../../components/fabro-workflow", features = ["test-support"] }

46
lib/apps/fabro-cli/src/commands/exec.rs
View file

@ -18,7 +18,7 @@ use fabro_llm::lithos_catalog::{Catalog, CatalogProvider};
use fabro_llm::middleware::{Call, Middleware, Next, Output};
use fabro_llm::{Client, ClientOptions, Error as LlmError, ErrorKind};
use fabro_mcp::config::McpServerSettings;
use fabro_mcp::connection_manager::McpConnectionManager;
use fabro_mcp::pebble::pebble_servers;
use fabro_sandbox::{RunSandbox, SecretRedactor, local_sandbox};
use fabro_static::EnvVars;
use fabro_types::settings::cli::OutputFormat as SettingsOutputFormat;
@ -627,7 +627,6 @@ async fn run_session(
]);
}
let mcp = start_mcp_servers(&mcp_servers, styles).await;
let environment: Arc<dyn Environment> = Arc::clone(&sandbox) as Arc<dyn Environment>;
let mut builder = CodingAgent::builder(client, environment)
.model(format!("{provider_id}/{model}"))
@ -635,9 +634,10 @@ async fn run_session(
.tool_middleware(Arc::new(permission_middleware))
.redactor(Arc::new(SecretRedactor))
.web_fetch_summarizer(summarizer_model(&catalog, &provider_id, &model))
.mcp_servers(pebble_servers(&mcp_servers))
.subagents(SubagentOptions::enabled());
if let Some(manager) = &mcp {
builder = builder.tools(manager.tools());
if let Some(routes) = sandbox.port_routes() {
builder = builder.port_routes(routes);
}
if let Some(search) = SearchBackend::from_secrets(&cli_search_secrets()) {
builder = builder.search_provider(Arc::new(search));
@ -646,6 +646,12 @@ async fn run_session(
.build()
.await
.context("failed to start the agent session")?;
if matches!(
args.output_format.unwrap_or(ExecOutputFormat::Text),
ExecOutputFormat::Text
) {
print_mcp_servers(&agent, styles);
}
// SIGINT ends the prompt; the session shuts down as cancelled.
let cancel_token = CancellationToken::new();
@ -703,36 +709,32 @@ async fn run_session(
.map_err(|error| anyhow::Error::new(SessionError::from(error)))
}
/// Connect the configured MCP servers, reporting each outcome on stderr.
/// Report what became of each configured MCP server on stderr: pebble
/// started them while the agent was built, so the outcomes are read from the
/// agent rather than from a stream that had no subscriber yet.
#[allow(
clippy::print_stderr,
reason = "MCP connection outcomes are diagnostics for the person running the CLI."
)]
async fn start_mcp_servers(
servers: &[McpServerSettings],
styles: &Styles,
) -> Option<Arc<McpConnectionManager>> {
if servers.is_empty() {
return None;
}
let mut manager = McpConnectionManager::new();
for (server_name, result) in manager.start_servers(servers).await {
match result {
Ok(tool_count) => eprintln!(
fn print_mcp_servers(agent: &CodingAgent, styles: &Styles) {
for status in agent.snapshot().mcp_servers() {
match &status.error {
None => eprintln!(
"{}",
styles
.dim
.apply_to(format!("[mcp] {server_name}: {tool_count} tools"))
styles.dim.apply_to(format!(
"[mcp] {}: {} tools",
status.server,
status.tools.len()
))
),
Err(error) => eprintln!(
Some(error) => eprintln!(
"{}",
styles
.red
.apply_to(format!("[mcp] {server_name} failed: {error}"))
.apply_to(format!("[mcp] {} failed: {error}", status.server))
),
}
}
Some(Arc::new(manager))
}
#[allow(

2
lib/apps/fabro-cli/tests/it/cmd/mcp.rs
View file

@ -18,8 +18,8 @@ use std::time::{Duration, Instant};
use chrono::{DateTime, Duration as ChronoDuration, Utc};
use fabro_client::{AuthEntry, AuthStore, DevTokenEntry, OAuthEntry, StoredSubject};
use fabro_mcp::client::McpClient;
use fabro_mcp::config::{McpServerSettings, McpTransport};
use fabro_mcp::test_support::McpStdioTestClient as McpClient;
use fabro_test::{fabro_json_snapshot, fabro_snapshot, test_context};
use fabro_types::{Graph, RunId, WorkflowSettings, test_support};
use httpmock::Method::{GET, POST};

39
lib/components/fabro-mcp/Cargo.toml
View file

@ -4,37 +4,32 @@ edition.workspace = true
version.workspace = true
publish = false
license.workspace = true
description = "MCP (Model Context Protocol) client for connecting to external tool servers"
description = "MCP server settings for fabro's agents, and how they reach pebble"
[lib]
doctest = false
[features]
# A stdio MCP client for tests of fabro's own MCP server. Production agents
# reach MCP servers through pebble; nothing here links into a normal build.
test-support = ["dep:anyhow", "dep:rmcp", "dep:serde_json", "dep:tokio", "dep:tracing"]
[lints]
workspace = true
[dependencies]
anyhow.workspace = true
fabro-config = { path = "../../foundation/fabro-config" }
fabro-http.workspace = true
fabro-types = { path = "../../foundation/fabro-types" }
pebble-coding-agent.workspace = true
serde.workspace = true
serde_json.workspace = true
tokio.workspace = true
futures.workspace = true
tracing.workspace = true
thiserror.workspace = true
sse-stream.workspace = true
rmcp = { workspace = true, features = [
"client",
"macros",
"schemars",
"server",
"transport-child-process",
"transport-streamable-http-client-reqwest",
] }
anyhow = { workspace = true, optional = true }
rmcp = { workspace = true, features = ["client", "transport-child-process"], optional = true }
serde_json = { workspace = true, optional = true }
tokio = { workspace = true, optional = true }
tracing = { workspace = true, optional = true }
[dev-dependencies]
axum.workspace = true
tokio = { workspace = true, features = ["test-util", "macros"] }
tokio-stream.workspace = true
# The test-support client's dependencies, so `cfg(test)` builds see them too.
anyhow.workspace = true
rmcp = { workspace = true, features = ["client", "transport-child-process"] }
serde_json.workspace = true
tokio.workspace = true
tracing.workspace = true

296
lib/components/fabro-mcp/src/client.rs
View file

@ -1,296 +0,0 @@
use std::process::Stdio;
use std::sync::Arc;
use std::time::Duration;
use anyhow::{Context as _, Result, anyhow};
use rmcp::model::{CallToolRequestParams, CallToolResult};
use rmcp::service::{RoleClient, RunningService, serve_client};
use rmcp::transport::StreamableHttpClientTransport;
use rmcp::transport::child_process::TokioChildProcess;
use rmcp::transport::streamable_http_client::StreamableHttpClientTransportConfig;
use tokio::process::Command;
use tokio::sync::Mutex;
use tokio::time;
use tracing::{debug, error, info, warn};
use crate::client_handler::LoggingClientHandler;
use crate::config::{McpHttpProtocol, McpServerSettings, McpTransport};
use crate::http_transport::headers_from_pairs;
use crate::sse_client::SseClientTransport;
enum ClientState {
/// Transport created but handshake not yet performed.
Connecting(Option<PendingTransport>),
/// Handshake complete, ready for tool calls.
Ready(Arc<RunningService<RoleClient, LoggingClientHandler>>),
/// Connection was explicitly closed.
Closed,
}
enum PendingTransport {
Stdio(TokioChildProcess),
Http(StreamableHttpClientTransport<fabro_http::HttpClient>),
Sse(SseClientTransport),
}
/// MCP client wrapping the rmcp SDK. Handles stdio and HTTP transports.
pub struct McpClient {
server_name: String,
state: Mutex<ClientState>,
}
impl McpClient {
/// Create a new MCP client from config. Does not connect yet — call
/// `initialize()`.
pub fn new(config: &McpServerSettings) -> Result<Self> {
let transport = match &config.transport {
McpTransport::Stdio { command, env } => {
let (program, args) = command.split_first().ok_or_else(|| {
anyhow!("MCP server '{}': command must not be empty", config.name)
})?;
let mut cmd = Command::new(program);
cmd.args(args)
.stdin(Stdio::piped())
.stdout(Stdio::piped())
.stderr(Stdio::piped())
.kill_on_drop(true);
if config.clear_env {
cmd.env_clear();
}
if !env.is_empty() {
cmd.envs(env);
}
if let Some(current_dir) = config.current_dir.as_ref() {
cmd.current_dir(current_dir);
}
#[cfg(unix)]
cmd.process_group(0);
let transport = TokioChildProcess::new(cmd)
.with_context(|| format!("failed to spawn MCP server '{}'", config.name))?;
PendingTransport::Stdio(transport)
}
McpTransport::Http {
protocol,
url,
headers,
} => {
let headers = headers_from_pairs(headers)?;
let mut builder = fabro_http::HttpClientBuilder::new();
if !headers.is_empty() {
builder = builder.default_headers(headers);
}
let http_client = builder.build()?;
match protocol {
McpHttpProtocol::StreamableHttp => {
let http_config =
StreamableHttpClientTransportConfig::with_uri(url.clone());
let transport =
StreamableHttpClientTransport::with_client(http_client, http_config);
PendingTransport::Http(transport)
}
McpHttpProtocol::Sse => {
PendingTransport::Sse(SseClientTransport::new(url, http_client)?)
}
}
}
McpTransport::Sandbox { .. } => {
return Err(anyhow!(
"MCP server '{}': Sandbox transport must be resolved to Http before connecting",
config.name
));
}
};
let transport_type = match &transport {
PendingTransport::Stdio(_) => "stdio",
PendingTransport::Http(_) => "http",
PendingTransport::Sse(_) => "sse",
};
debug!(server = %config.name, transport = transport_type, "Creating MCP client");
Ok(Self {
server_name: config.name.clone(),
state: Mutex::new(ClientState::Connecting(Some(transport))),
})
}
/// Perform the initialization handshake with the MCP server.
pub async fn initialize(&self, timeout: Duration) -> Result<()> {
let handler = LoggingClientHandler;
let service = {
let mut guard = self.state.lock().await;
let transport = match &mut *guard {
ClientState::Connecting(t) => t
.take()
.ok_or_else(|| anyhow!("client already initializing"))?,
ClientState::Ready(_) => return Err(anyhow!("client already initialized")),
ClientState::Closed => return Err(anyhow!("MCP client is shut down")),
};
// Drop the lock before the blocking handshake
drop(guard);
debug!(server = %self.server_name, "Starting MCP server handshake");
let handshake = async {
match transport {
PendingTransport::Stdio(t) => serve_client(handler.clone(), t).await,
PendingTransport::Http(t) => serve_client(handler.clone(), t).await,
PendingTransport::Sse(t) => serve_client(handler.clone(), t).await,
}
};
let service = time::timeout(timeout, handshake)
.await
.map_err(|_| {
error!(server = %self.server_name, timeout_secs = timeout.as_secs(), "MCP server handshake timed out");
anyhow!(
"timed out initializing MCP server '{}' after {:?}",
self.server_name,
timeout
)
})?
.map_err(|e| {
error!(server = %self.server_name, error = %e, "MCP server handshake failed");
anyhow!(
"failed to initialize MCP server '{}': {}",
self.server_name,
e
)
})?;
let peer_info = service.peer().peer_info();
if let Some(info) = peer_info {
info!(
server = %self.server_name,
server_name = %info.server_info.name,
server_version = %info.server_info.version,
"MCP server initialized"
);
}
Arc::new(service)
};
let mut guard = self.state.lock().await;
*guard = ClientState::Ready(service);
Ok(())
}
/// List all tools exposed by this server.
/// Returns `(name, description, input_schema)` tuples.
pub async fn list_tools(&self) -> Result<Vec<(String, String, serde_json::Value)>> {
let service = self.service().await?;
let result = service.list_all_tools().await.map_err(|e| {
anyhow!(
"failed to list tools from MCP server '{}': {}",
self.server_name,
e
)
})?;
let tools: Vec<_> = result
.into_iter()
.map(|tool| {
let name = tool.name.to_string();
let description = tool.description.as_deref().unwrap_or("").to_string();
let input_schema = serde_json::to_value(&*tool.input_schema).unwrap_or_default();
(name, description, input_schema)
})
.collect();
debug!(server = %self.server_name, tool_count = tools.len(), "Listed MCP server tools");
Ok(tools)
}
/// Call a tool on this server.
pub async fn call_tool(
&self,
name: &str,
arguments: serde_json::Value,
timeout: Duration,
) -> Result<CallToolResult> {
let service = self.service().await?;
let args = match arguments {
serde_json::Value::Object(map) => Some(map),
serde_json::Value::Null => None,
other => {
return Err(anyhow!(
"MCP tool arguments must be a JSON object, got {other}"
));
}
};
let mut params = CallToolRequestParams::new(name.to_string());
if let Some(arguments) = args {
params = params.with_arguments(arguments);
}
debug!(server = %self.server_name, tool = %name, "Calling MCP tool");
let result = time::timeout(timeout, service.call_tool(params))
.await
.map_err(|_| {
warn!(server = %self.server_name, tool = %name, timeout_secs = timeout.as_secs(), "MCP tool call timed out");
anyhow!(
"timed out calling tool '{}' on MCP server '{}' after {:?}",
name,
self.server_name,
timeout
)
})?
.map_err(|e| {
anyhow!(
"failed to call tool '{}' on MCP server '{}': {}",
name,
self.server_name,
e
)
})?;
Ok(result)
}
pub async fn shutdown(self) -> Result<()> {
let service = {
let mut guard = self.state.lock().await;
match std::mem::replace(&mut *guard, ClientState::Closed) {
ClientState::Connecting(_) | ClientState::Closed => None,
ClientState::Ready(service) => Some(service),
}
};
if let Some(service) = service {
match Arc::try_unwrap(service) {
Ok(mut service) => {
service
.close_with_timeout(Duration::from_secs(2))
.await
.context("failed to shut down MCP client")?;
}
Err(service) => {
service.cancellation_token().cancel();
}
}
}
Ok(())
}
async fn service(&self) -> Result<Arc<RunningService<RoleClient, LoggingClientHandler>>> {
let guard = self.state.lock().await;
match &*guard {
ClientState::Ready(service) => Ok(Arc::clone(service)),
ClientState::Connecting(_) => Err(anyhow!("MCP client not initialized")),
ClientState::Closed => Err(anyhow!("MCP client is shut down")),
}
}
}

104
lib/components/fabro-mcp/src/client_handler.rs
View file

@ -1,104 +0,0 @@
use rmcp::model::{
CancelledNotificationParam, ClientCapabilities, ClientInfo, Implementation, LoggingLevel,
LoggingMessageNotificationParam, ProgressNotificationParam, ProtocolVersion,
ResourceUpdatedNotificationParam,
};
use rmcp::service::NotificationContext;
use rmcp::{ClientHandler, RoleClient};
use tracing::{debug, error, info, warn};
/// Minimal MCP client handler that logs server notifications via tracing.
#[derive(Clone)]
pub(crate) struct LoggingClientHandler;
impl ClientHandler for LoggingClientHandler {
fn get_info(&self) -> ClientInfo {
ClientInfo::new(
ClientCapabilities::default(),
Implementation::new("fabro-mcp", env!("CARGO_PKG_VERSION")),
)
.with_protocol_version(ProtocolVersion::V_2025_03_26)
}
async fn on_cancelled(
&self,
params: CancelledNotificationParam,
_context: NotificationContext<RoleClient>,
) {
info!(
request_id = %params.request_id,
reason = ?params.reason,
"MCP server cancelled request"
);
}
async fn on_progress(
&self,
params: ProgressNotificationParam,
_context: NotificationContext<RoleClient>,
) {
debug!(
progress_token = ?params.progress_token,
progress = params.progress,
total = ?params.total,
message = ?params.message,
"MCP server progress"
);
}
async fn on_resource_updated(
&self,
params: ResourceUpdatedNotificationParam,
_context: NotificationContext<RoleClient>,
) {
info!(uri = %params.uri, "MCP server resource updated");
}
async fn on_resource_list_changed(&self, _context: NotificationContext<RoleClient>) {
info!("MCP server resource list changed");
}
async fn on_tool_list_changed(&self, _context: NotificationContext<RoleClient>) {
info!("MCP server tool list changed");
}
async fn on_prompt_list_changed(&self, _context: NotificationContext<RoleClient>) {
info!("MCP server prompt list changed");
}
async fn on_logging_message(
&self,
params: LoggingMessageNotificationParam,
_context: NotificationContext<RoleClient>,
) {
let logger = params.logger.as_deref();
let data_str = params.data.to_string();
let truncated: &str = if data_str.len() > 200 {
// Safety: find a char boundary at or before 200 bytes
let end = (0..=200)
.rev()
.find(|&i| data_str.is_char_boundary(i))
.unwrap_or(0);
&data_str[..end]
} else {
&data_str
};
match params.level {
LoggingLevel::Emergency
| LoggingLevel::Alert
| LoggingLevel::Critical
| LoggingLevel::Error => {
error!(level = ?params.level, ?logger, data = %truncated, "MCP server log");
}
LoggingLevel::Warning => {
warn!(level = ?params.level, ?logger, data = %truncated, "MCP server log");
}
LoggingLevel::Notice | LoggingLevel::Info => {
info!(level = ?params.level, ?logger, data = %truncated, "MCP server log");
}
LoggingLevel::Debug => {
debug!(level = ?params.level, ?logger, data = %truncated, "MCP server log");
}
}
}
}

408
lib/components/fabro-mcp/src/connection_manager.rs
View file

@ -1,408 +0,0 @@
use std::collections::HashMap;
use std::sync::Arc;
use std::time::Duration;
use anyhow::Result;
use pebble_coding_agent::tools::{RegisteredTool, ToolError, ToolSource};
use rmcp::model::{CallToolResult, RawContent};
use tracing::{error, info};
use crate::client::McpClient;
use crate::config::McpServerSettings;
const MCP_TOOL_NAME_DELIMITER: &str = "__";
/// Produce a qualified tool name: `mcp__{server}__{tool}`.
/// Non-alphanumeric characters in `server` and `tool` (except `_`) are replaced
/// with `_`.
#[must_use]
pub fn qualified_tool_name(server: &str, tool: &str) -> String {
format!(
"mcp{delim}{server}{delim}{tool}",
delim = MCP_TOOL_NAME_DELIMITER,
server = sanitize_name(server),
tool = sanitize_name(tool),
)
}
/// Parse a qualified tool name back into `(server, tool)`.
/// Returns `None` if the name doesn't match the expected pattern.
#[must_use]
pub fn parse_qualified_name(qualified: &str) -> Option<(String, String)> {
let rest = qualified.strip_prefix("mcp")?;
let rest = rest.strip_prefix(MCP_TOOL_NAME_DELIMITER)?;
let idx = rest.find(MCP_TOOL_NAME_DELIMITER)?;
let server = &rest[..idx];
let tool = &rest[idx + MCP_TOOL_NAME_DELIMITER.len()..];
if server.is_empty() || tool.is_empty() {
return None;
}
Some((server.to_string(), tool.to_string()))
}
fn sanitize_name(name: &str) -> String {
name.chars()
.map(|c| {
if c.is_alphanumeric() || c == '_' {
c
} else {
'_'
}
})
.collect()
}
/// Convert an MCP `CallToolResult` to a `Result<String, String>`.
/// `Ok(text)` for success, `Err(text)` if the result has `is_error` set.
pub fn call_result_to_string(result: &CallToolResult) -> Result<String, String> {
let text = result
.content
.iter()
.map(|c| match &c.raw {
RawContent::Text(t) => t.text.clone(),
RawContent::Image(_) => "[image content]".to_string(),
RawContent::Audio(_) => "[audio content]".to_string(),
RawContent::Resource(_) | RawContent::ResourceLink(_) => {
"[resource content]".to_string()
}
})
.collect::<Vec<_>>()
.join("\n");
if result.is_error.unwrap_or(false) {
Err(text)
} else {
Ok(text)
}
}
/// Tool info stored per-tool in the connection manager.
#[derive(Debug, Clone)]
pub struct ToolInfo {
pub server_name: String,
pub original_tool_name: String,
pub description: String,
pub input_schema: serde_json::Value,
}
struct ServerConnection {
client: Arc<McpClient>,
tool_timeout: Duration,
}
/// Manages connections to multiple MCP servers and their tools.
pub struct McpConnectionManager {
clients: HashMap<String, ServerConnection>,
tools: HashMap<String, ToolInfo>,
}
impl McpConnectionManager {
#[must_use]
pub fn new() -> Self {
Self {
clients: HashMap::new(),
tools: HashMap::new(),
}
}
/// Start all configured MCP servers. Failed servers are logged but don't
/// block others. Returns a list of `(server_name, result)` for each
/// server.
pub async fn start_servers(
&mut self,
configs: &[McpServerSettings],
) -> Vec<(String, Result<usize>)> {
let mut results = Vec::new();
for config in configs {
match self.start_one_server(config).await {
Ok(tool_count) => {
info!(server = %config.name, tools = tool_count, "MCP server ready");
results.push((config.name.clone(), Ok(tool_count)));
}
Err(e) => {
error!(server = %config.name, error = %e, "MCP server failed to start");
results.push((config.name.clone(), Err(e)));
}
}
}
results
}
async fn start_one_server(&mut self, config: &McpServerSettings) -> Result<usize> {
let client = McpClient::new(config)?;
client.initialize(config.startup_timeout()).await?;
let tools = client.list_tools().await?;
let tool_count = tools.len();
for (name, description, input_schema) in tools {
let qualified = qualified_tool_name(&config.name, &name);
self.tools.insert(qualified, ToolInfo {
server_name: config.name.clone(),
original_tool_name: name,
description,
input_schema,
});
}
self.clients.insert(config.name.clone(), ServerConnection {
client: Arc::new(client),
tool_timeout: config.tool_timeout(),
});
Ok(tool_count)
}
/// All tools across all connected servers.
#[must_use]
pub fn all_tools(&self) -> &HashMap<String, ToolInfo> {
&self.tools
}
/// Names-only tool summaries for the given server, sorted by qualified
/// name. Returns `(qualified_name, original_tool_name)` pairs. Useful
/// for emitting deterministic `agent.mcp.ready` payloads without
/// leaking descriptions or input schemas.
#[must_use]
pub fn tool_summaries_for_server(&self, server_name: &str) -> Vec<(String, String)> {
let mut summaries: Vec<(String, String)> = self
.tools
.iter()
.filter(|(_, info)| info.server_name == server_name)
.map(|(qualified, info)| (qualified.clone(), info.original_tool_name.clone()))
.collect();
summaries.sort_by(|a, b| a.0.cmp(&b.0));
summaries
}
/// Every connected server's tools as coding-agent tools, each carrying
/// its MCP origin. Sorted by qualified name so registration order is
/// deterministic.
#[must_use]
pub fn tools(self: &Arc<Self>) -> Vec<RegisteredTool> {
let mut tools: Vec<(&String, &ToolInfo)> = self.tools.iter().collect();
tools.sort_by(|left, right| left.0.cmp(right.0));
tools
.into_iter()
.map(|(qualified_name, info)| {
let manager = Arc::clone(self);
let name = qualified_name.clone();
RegisteredTool::function(
qualified_name.clone(),
info.description.clone(),
info.input_schema.clone(),
move |_context, arguments| {
let manager = Arc::clone(&manager);
let name = name.clone();
async move {
let result = manager
.call_tool(&name, arguments)
.await
.map_err(|error| ToolError::execution(error.to_string()))?;
call_result_to_string(&result).map_err(ToolError::execution)
}
},
)
.with_source(ToolSource::Mcp {
server_name: info.server_name.clone(),
original_name: info.original_tool_name.clone(),
})
})
.collect()
}
/// Call a tool by its qualified name.
pub async fn call_tool(
&self,
qualified_name: &str,
arguments: serde_json::Value,
) -> Result<CallToolResult> {
let info = self
.tools
.get(qualified_name)
.ok_or_else(|| anyhow::anyhow!("unknown MCP tool: {qualified_name}"))?;
let connection = self
.clients
.get(&info.server_name)
.ok_or_else(|| anyhow::anyhow!("no client for MCP server: {}", info.server_name))?;
connection
.client
.call_tool(&info.original_tool_name, arguments, connection.tool_timeout)
.await
}
}
impl Default for McpConnectionManager {
fn default() -> Self {
Self::new()
}
}
#[cfg(test)]
mod tests {
use rmcp::model::Content;
use super::*;
#[test]
fn qualified_tool_name_basic() {
assert_eq!(
qualified_tool_name("filesystem", "read_file"),
"mcp__filesystem__read_file"
);
}
#[test]
fn qualified_tool_name_sanitizes_special_chars() {
assert_eq!(
qualified_tool_name("my-server", "read.file"),
"mcp__my_server__read_file"
);
}
#[test]
fn qualified_tool_name_preserves_underscores() {
assert_eq!(
qualified_tool_name("my_server", "read_file"),
"mcp__my_server__read_file"
);
}
#[test]
fn parse_qualified_name_roundtrip() {
let qualified = qualified_tool_name("filesystem", "read_file");
let (server, tool) = parse_qualified_name(&qualified).unwrap();
assert_eq!(server, "filesystem");
assert_eq!(tool, "read_file");
}
#[test]
fn parse_qualified_name_with_sanitized_input() {
let qualified = qualified_tool_name("my-server", "read.file");
let (server, tool) = parse_qualified_name(&qualified).unwrap();
assert_eq!(server, "my_server");
assert_eq!(tool, "read_file");
}
#[test]
fn parse_qualified_name_invalid_prefix() {
assert!(parse_qualified_name("not_mcp__server__tool").is_none());
}
#[test]
fn parse_qualified_name_missing_delimiter() {
assert!(parse_qualified_name("mcp__serveronly").is_none());
}
#[test]
fn parse_qualified_name_empty_parts() {
assert!(parse_qualified_name("mcp____tool").is_none());
}
fn make_text_content(text: &str) -> Content {
Content::text(text)
}
fn make_call_result(content: Vec<Content>, is_error: Option<bool>) -> CallToolResult {
if is_error == Some(true) {
CallToolResult::error(content)
} else {
CallToolResult::success(content)
}
}
#[test]
fn call_result_to_string_text_success() {
let result = make_call_result(vec![make_text_content("hello world")], Some(false));
assert_eq!(
call_result_to_string(&result),
Ok("hello world".to_string())
);
}
#[test]
fn call_result_to_string_text_error() {
let result = make_call_result(vec![make_text_content("something failed")], Some(true));
assert_eq!(
call_result_to_string(&result),
Err("something failed".to_string())
);
}
#[test]
fn call_result_to_string_multiple_blocks_concatenated() {
let result = make_call_result(
vec![make_text_content("line 1"), make_text_content("line 2")],
None,
);
assert_eq!(
call_result_to_string(&result),
Ok("line 1\nline 2".to_string())
);
}
#[test]
fn call_result_to_string_image_placeholder() {
let result = CallToolResult::success(vec![Content::image("base64data", "image/png")]);
assert_eq!(
call_result_to_string(&result),
Ok("[image content]".to_string())
);
}
#[test]
fn call_result_to_string_none_is_error_treated_as_success() {
let result = make_call_result(vec![make_text_content("ok")], None);
assert_eq!(call_result_to_string(&result), Ok("ok".to_string()));
}
#[test]
fn connection_manager_new_has_empty_tools() {
let mgr = McpConnectionManager::new();
assert!(mgr.all_tools().is_empty());
}
#[test]
fn tool_summaries_for_server_filters_and_sorts_by_qualified_name() {
let mut mgr = McpConnectionManager::new();
mgr.tools
.insert(qualified_tool_name("github", "list_issues"), ToolInfo {
server_name: "github".to_string(),
original_tool_name: "list_issues".to_string(),
description: "list issues".to_string(),
input_schema: serde_json::json!({}),
});
mgr.tools
.insert(qualified_tool_name("github", "create_issue"), ToolInfo {
server_name: "github".to_string(),
original_tool_name: "create_issue".to_string(),
description: "create issue".to_string(),
input_schema: serde_json::json!({}),
});
mgr.tools
.insert(qualified_tool_name("other", "noop"), ToolInfo {
server_name: "other".to_string(),
original_tool_name: "noop".to_string(),
description: "noop".to_string(),
input_schema: serde_json::json!({}),
});
let summaries = mgr.tool_summaries_for_server("github");
assert_eq!(summaries.len(), 2);
assert_eq!(summaries[0].0, "mcp__github__create_issue");
assert_eq!(summaries[0].1, "create_issue");
assert_eq!(summaries[1].0, "mcp__github__list_issues");
assert_eq!(summaries[1].1, "list_issues");
let other = mgr.tool_summaries_for_server("other");
assert_eq!(other.len(), 1);
assert_eq!(other[0].0, "mcp__other__noop");
assert_eq!(other[0].1, "noop");
let none = mgr.tool_summaries_for_server("missing");
assert!(none.is_empty());
}
}

35
lib/components/fabro-mcp/src/http_transport.rs
View file

@ -1,35 +0,0 @@
#![expect(
clippy::disallowed_types,
reason = "MCP HTTP helpers parse operator-provided endpoint URLs; callers control what is logged"
)]
use std::collections::HashMap;
use anyhow::{Context as _, Result};
use fabro_http::{HeaderMap, HeaderName, HeaderValue, Url};
use crate::config::McpHttpProtocol;
pub fn sandbox_mcp_http_url(protocol: McpHttpProtocol, preview_url: &str) -> Result<String> {
match protocol {
McpHttpProtocol::StreamableHttp => Ok(preview_url.to_string()),
McpHttpProtocol::Sse => {
let mut url = Url::parse(preview_url).context("invalid sandbox MCP preview URL")?;
let path = url.path().trim_end_matches('/');
url.set_path(&format!("{path}/sse"));
Ok(url.to_string())
}
}
}
pub(crate) fn headers_from_pairs(headers: &HashMap<String, String>) -> Result<HeaderMap> {
let mut header_map = HeaderMap::new();
for (key, value) in headers {
let name = HeaderName::from_bytes(key.as_bytes())
.with_context(|| format!("invalid header name '{key}'"))?;
let val = HeaderValue::from_str(value)
.with_context(|| format!("invalid header value for '{key}'"))?;
header_map.insert(name, val);
}
Ok(header_map)
}

16
lib/components/fabro-mcp/src/lib.rs
View file

@ -1,6 +1,12 @@
pub mod client;
mod client_handler;
//! MCP server settings for fabro's agents, and how they reach pebble.
//!
//! Fabro configures MCP servers in its settings ([`config`]); pebble starts
//! them, registers their tools, and closes them with the agent. [`pebble`]
//! maps one to the other. The stdio client fabro once ran itself is gone;
//! [`test_support`] keeps a small one for the tests of fabro's own MCP server.
pub mod config;
pub mod connection_manager;
pub mod http_transport;
mod sse_client;
pub mod pebble;
#[cfg(any(test, feature = "test-support"))]
pub mod test_support;

191
lib/components/fabro-mcp/src/pebble.rs Normal file
View file

@ -0,0 +1,191 @@
//! Fabro's MCP server settings as the servers pebble starts.
//!
//! Fabro's three transports are pebble's three placements: a `stdio` server
//! is a child of fabro's process, an `http` server is reached directly, and a
//! `sandbox` server is launched in the run sandbox and reached through the
//! sandbox's route to its port. Fabro has always reached a sandbox-hosted SSE
//! server at `/sse` under that route, and still does.
use std::collections::{BTreeMap, HashMap};
use pebble_coding_agent::mcp::{McpHttpProtocol as PebbleProtocol, McpPlacement, McpServer};
use crate::config::{McpHttpProtocol, McpServerSettings, McpTransport};
/// Where a sandbox-hosted SSE server serves its event stream.
const SSE_PATH: &str = "/sse";
/// The pebble server `settings` describes.
#[must_use]
pub fn pebble_server(settings: &McpServerSettings) -> McpServer {
let placement = match &settings.transport {
McpTransport::Stdio { command, env } => McpPlacement::Stdio {
command: command.clone(),
env: sorted(env),
current_dir: settings.current_dir.clone(),
clear_env: settings.clear_env,
},
McpTransport::Http {
protocol,
url,
headers,
} => McpPlacement::Http {
url: url.clone(),
headers: sorted(headers),
protocol: pebble_protocol(*protocol),
},
McpTransport::Sandbox {
protocol,
command,
port,
env,
} => McpPlacement::Environment {
command: command.clone(),
port: *port,
env: sorted(env),
protocol: pebble_protocol(*protocol),
path: matches!(protocol, McpHttpProtocol::Sse).then(|| SSE_PATH.to_string()),
},
};
McpServer::new(settings.name.clone(), placement)
.with_startup_timeout(settings.startup_timeout())
.with_tool_timeout(settings.tool_timeout())
}
/// The pebble servers for every configured server, in configuration order.
pub fn pebble_servers<'a>(
settings: impl IntoIterator<Item = &'a McpServerSettings>,
) -> Vec<McpServer> {
settings.into_iter().map(pebble_server).collect()
}
fn pebble_protocol(protocol: McpHttpProtocol) -> PebbleProtocol {
match protocol {
McpHttpProtocol::StreamableHttp => PebbleProtocol::StreamableHttp,
McpHttpProtocol::Sse => PebbleProtocol::Sse,
}
}
fn sorted(map: &HashMap<String, String>) -> BTreeMap<String, String> {
map.iter()
.map(|(key, value)| (key.clone(), value.clone()))
.collect()
}
#[cfg(test)]
mod tests {
use std::path::PathBuf;
use std::time::Duration;
use super::*;
#[test]
fn a_stdio_server_keeps_its_directory_and_environment_policy() {
let settings = McpServerSettings {
name: "echo".into(),
transport: McpTransport::Stdio {
command: vec!["python3".into(), "server.py".into()],
env: HashMap::from([("B".into(), "2".into()), ("A".into(), "1".into())]),
},
current_dir: Some(PathBuf::from("/work")),
clear_env: true,
startup_timeout_secs: 7,
tool_timeout_secs: 9,
};
let server = pebble_server(&settings);
assert_eq!(server.name(), "echo");
assert_eq!(server.startup_timeout(), Duration::from_secs(7));
assert_eq!(server.tool_timeout(), Duration::from_secs(9));
match server.placement() {
McpPlacement::Stdio {
command,
env,
current_dir,
clear_env,
} => {
assert_eq!(command, &["python3", "server.py"]);
assert_eq!(
env.keys().collect::<Vec<_>>(),
["A", "B"],
"a sorted map, so the launch is deterministic"
);
assert_eq!(current_dir.as_deref(), Some(std::path::Path::new("/work")));
assert!(*clear_env);
}
other => panic!("expected a stdio placement, got {other:?}"),
}
}
#[test]
fn an_http_server_keeps_its_protocol_and_headers() {
let settings = McpServerSettings {
name: "web".into(),
transport: McpTransport::Http {
protocol: McpHttpProtocol::Sse,
url: "https://mcp.example/sse".into(),
headers: HashMap::from([("authorization".into(), "Bearer x".into())]),
},
..McpServerSettings::default()
};
match pebble_server(&settings).placement() {
McpPlacement::Http {
url,
headers,
protocol,
} => {
assert_eq!(url, "https://mcp.example/sse");
assert_eq!(
headers.get("authorization").map(String::as_str),
Some("Bearer x")
);
assert_eq!(*protocol, PebbleProtocol::Sse);
}
other => panic!("expected an http placement, got {other:?}"),
}
}
#[test]
fn a_sandbox_server_is_an_environment_placement_with_fabros_sse_path() {
let sse = McpServerSettings {
name: "playwright".into(),
transport: McpTransport::Sandbox {
protocol: McpHttpProtocol::Sse,
command: vec!["npx".into(), "@playwright/mcp".into()],
port: 3100,
env: HashMap::new(),
},
..McpServerSettings::default()
};
match pebble_server(&sse).placement() {
McpPlacement::Environment {
port,
protocol,
path,
..
} => {
assert_eq!(*port, 3100);
assert_eq!(*protocol, PebbleProtocol::Sse);
assert_eq!(path.as_deref(), Some("/sse"));
}
other => panic!("expected an environment placement, got {other:?}"),
}
let streamable = McpServerSettings {
transport: McpTransport::Sandbox {
protocol: McpHttpProtocol::StreamableHttp,
command: vec!["server".into()],
port: 3100,
env: HashMap::new(),
},
..sse
};
match pebble_server(&streamable).placement() {
McpPlacement::Environment { path, .. } => {
assert!(
path.is_none(),
"a streamable server is reached at the route itself"
);
}
other => panic!("expected an environment placement, got {other:?}"),
}
}
}

319
lib/components/fabro-mcp/src/sse_client.rs
View file

@ -1,319 +0,0 @@
#![expect(
clippy::disallowed_types,
reason = "SSE transport needs URL parsing for internal request routing; error messages omit raw URLs"
)]
use std::future::Future;
use anyhow::{Context as _, Result, anyhow};
use fabro_http::{Url, header};
use futures::{StreamExt as _, TryStreamExt as _};
use rmcp::RoleClient;
use rmcp::model::ServerJsonRpcMessage;
use rmcp::service::{RxJsonRpcMessage, TxJsonRpcMessage};
use rmcp::transport::Transport;
use sse_stream::{Sse, SseStream};
use tokio::sync::{mpsc, watch};
use tokio::task::JoinHandle;
const MAX_SSE_MESSAGE_BYTES: usize = 1024 * 1024;
pub(crate) struct SseClientTransport {
client: fabro_http::HttpClient,
endpoint_rx: watch::Receiver<Option<String>>,
messages_rx: mpsc::Receiver<ServerJsonRpcMessage>,
stream_task: Option<JoinHandle<()>>,
}
impl SseClientTransport {
pub(crate) fn new(url: &str, client: fabro_http::HttpClient) -> Result<Self> {
let (endpoint_tx, endpoint_rx) = watch::channel(None);
let (messages_tx, messages_rx) = mpsc::channel(64);
let sse_url = Url::parse(url).context("invalid SSE MCP URL")?;
let stream_client = client.clone();
let stream_task = tokio::spawn(async move {
if let Err(err) =
read_sse_stream(stream_client, sse_url, endpoint_tx, messages_tx).await
{
tracing::warn!(error = %err, "SSE MCP stream ended");
}
});
Ok(Self {
client,
endpoint_rx,
messages_rx,
stream_task: Some(stream_task),
})
}
}
impl Drop for SseClientTransport {
fn drop(&mut self) {
if let Some(stream_task) = &self.stream_task {
stream_task.abort();
}
}
}
impl Transport<RoleClient> for SseClientTransport {
type Error = SseClientError;
fn send(
&mut self,
item: TxJsonRpcMessage<RoleClient>,
) -> impl Future<Output = Result<(), Self::Error>> + Send + 'static {
let client = self.client.clone();
let mut endpoint_rx = self.endpoint_rx.clone();
async move {
let endpoint = wait_for_endpoint(&mut endpoint_rx).await?;
client
.post(endpoint)
.header(header::CONTENT_TYPE, "application/json")
.json(&item)
.send()
.await
.map_err(SseClientError::from_error)?
.error_for_status()
.map_err(SseClientError::from_error)?;
Ok(())
}
}
fn receive(&mut self) -> impl Future<Output = Option<RxJsonRpcMessage<RoleClient>>> + Send {
self.messages_rx.recv()
}
async fn close(&mut self) -> std::result::Result<(), Self::Error> {
if let Some(stream_task) = self.stream_task.take() {
stream_task.abort();
}
Ok(())
}
}
async fn wait_for_endpoint(
endpoint_rx: &mut watch::Receiver<Option<String>>,
) -> std::result::Result<String, SseClientError> {
loop {
if let Some(endpoint) = endpoint_rx.borrow().clone() {
return Ok(endpoint);
}
endpoint_rx
.changed()
.await
.map_err(|_| SseClientError::EndpointUnavailable)?;
}
}
async fn read_sse_stream(
client: fabro_http::HttpClient,
sse_url: Url,
endpoint_tx: watch::Sender<Option<String>>,
messages_tx: mpsc::Sender<ServerJsonRpcMessage>,
) -> std::result::Result<(), SseClientError> {
let request = client
.get(sse_url.clone())
.header(header::ACCEPT, "text/event-stream");
let response = request
.send()
.await
.map_err(SseClientError::from_error)?
.error_for_status()
.map_err(SseClientError::from_error)?;
let mut size_guard = SseSizeGuard::default();
let byte_stream = response.bytes_stream().map(move |chunk| {
let chunk = chunk.map_err(SseClientError::from_error)?;
size_guard.check_chunk(&chunk)?;
Ok::<_, SseClientError>(chunk)
});
let mut stream = SseStream::from_byte_stream(byte_stream);
while let Some(event) = stream
.try_next()
.await
.map_err(SseClientError::from_error)?
{
handle_sse_event(event, &sse_url, &endpoint_tx, &messages_tx).await?;
}
Ok(())
}
async fn handle_sse_event(
event: Sse,
sse_url: &Url,
endpoint_tx: &watch::Sender<Option<String>>,
messages_tx: &mpsc::Sender<ServerJsonRpcMessage>,
) -> std::result::Result<(), SseClientError> {
let data = event.data.unwrap_or_default();
match event.event.as_deref() {
Some("endpoint") => {
let endpoint =
resolve_endpoint_url(sse_url, data.trim()).context("invalid SSE MCP endpoint")?;
let _ = endpoint_tx.send(Some(endpoint.to_string()));
}
None | Some("" | "message") => {
if data.trim().is_empty() {
return Ok(());
}
let message: ServerJsonRpcMessage =
serde_json::from_str(&data).context("invalid SSE MCP JSON-RPC message")?;
messages_tx
.send(message)
.await
.map_err(|_| SseClientError::ReceiverClosed)?;
}
_ => {}
}
Ok(())
}
fn resolve_endpoint_url(sse_url: &Url, endpoint: &str) -> Result<Url> {
if endpoint.starts_with("//") {
return Err(anyhow!("SSE MCP endpoint must not be protocol-relative"));
}
let resolved = if endpoint.starts_with('/') {
let (path, query) = endpoint
.split_once('?')
.map_or((endpoint, None), |(path, query)| (path, Some(query)));
let base_path = sse_url.path().trim_end_matches('/');
let prefix = base_path.rsplit_once('/').map_or("", |(prefix, _)| prefix);
let mut url = sse_url.clone();
url.set_path(&format!("{prefix}{path}"));
url.set_query(query);
url
} else {
sse_url.join(endpoint)?
};
if resolved.origin() != sse_url.origin() {
return Err(anyhow!("SSE MCP endpoint origin must match SSE URL origin"));
}
Ok(resolved)
}
#[derive(Default)]
struct SseSizeGuard {
current_event_bytes: usize,
current_line_bytes: usize,
}
impl SseSizeGuard {
fn check_chunk(&mut self, chunk: &[u8]) -> std::result::Result<(), SseClientError> {
for byte in chunk {
self.current_event_bytes = self
.current_event_bytes
.checked_add(1)
.filter(|bytes| *bytes <= MAX_SSE_MESSAGE_BYTES)
.ok_or(SseClientError::MessageTooLarge {
max_bytes: MAX_SSE_MESSAGE_BYTES,
})?;
match *byte {
b'\n' => {
if self.current_line_bytes == 0 {
self.current_event_bytes = 0;
}
self.current_line_bytes = 0;
}
b'\r' => {}
_ => {
self.current_line_bytes += 1;
}
}
}
Ok(())
}
}
#[derive(Debug, thiserror::Error)]
pub(crate) enum SseClientError {
#[error(transparent)]
Source(#[from] anyhow::Error),
#[error("SSE MCP endpoint was not received before the stream closed")]
EndpointUnavailable,
#[error("SSE MCP receiver closed")]
ReceiverClosed,
#[error("SSE MCP message exceeds maximum size of {max_bytes} bytes")]
MessageTooLarge { max_bytes: usize },
}
impl SseClientError {
fn from_error(error: impl std::error::Error + Send + Sync + 'static) -> Self {
Self::Source(anyhow::Error::new(error))
}
}
#[cfg(test)]
mod tests {
use super::*;
fn sse_url() -> Url {
Url::parse("https://srv.example.com/sse").unwrap()
}
#[test]
fn accepts_relative_path_with_query() {
let resolved = resolve_endpoint_url(&sse_url(), "/messages?sessionId=abc").unwrap();
assert_eq!(
resolved.as_str(),
"https://srv.example.com/messages?sessionId=abc"
);
}
#[test]
fn accepts_same_origin_absolute_url() {
let resolved =
resolve_endpoint_url(&sse_url(), "https://srv.example.com/messages?s=1").unwrap();
assert_eq!(resolved.as_str(), "https://srv.example.com/messages?s=1");
}
#[test]
fn accepts_same_origin_default_port() {
let resolved =
resolve_endpoint_url(&sse_url(), "https://srv.example.com:443/messages").unwrap();
assert_eq!(resolved.origin(), sse_url().origin());
}
#[test]
fn rejects_cross_host_absolute_url() {
let err = resolve_endpoint_url(&sse_url(), "https://evil.example/steal").unwrap_err();
assert!(
err.to_string().contains("origin"),
"unexpected error: {err}"
);
}
#[test]
fn rejects_scheme_downgrade() {
let err = resolve_endpoint_url(&sse_url(), "http://srv.example.com/messages").unwrap_err();
assert!(
err.to_string().contains("origin"),
"unexpected error: {err}"
);
}
#[test]
fn rejects_port_mismatch() {
let err =
resolve_endpoint_url(&sse_url(), "https://srv.example.com:8443/messages").unwrap_err();
assert!(
err.to_string().contains("origin"),
"unexpected error: {err}"
);
}
#[test]
fn rejects_protocol_relative_url() {
let err = resolve_endpoint_url(&sse_url(), "//evil.example/steal").unwrap_err();
assert!(
err.to_string().contains("protocol-relative"),
"unexpected error: {err}"
);
}
}

200
lib/components/fabro-mcp/src/test_support.rs Normal file
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@ -0,0 +1,200 @@
//! A stdio MCP client for tests of fabro's own MCP server.
//!
//! Production agents reach MCP servers through pebble, which owns the client.
//! Fabro's `fabro mcp` command *is* an MCP server, and its tests need a
//! client to speak to it over its standard streams; this is that client and
//! nothing more. It links only into tests.
use std::process::Stdio;
use std::sync::Arc;
use std::time::Duration;
use anyhow::{Context as _, Result, anyhow};
use rmcp::model::{
CallToolRequestParams, CallToolResult, ClientCapabilities, ClientInfo, Implementation,
ProtocolVersion,
};
use rmcp::service::{RoleClient, RunningService, serve_client};
use rmcp::transport::child_process::TokioChildProcess;
use tokio::process::Command;
use tokio::sync::Mutex;
use tokio::time;
use crate::config::{McpServerSettings, McpTransport};
enum State {
Connecting(Option<TokioChildProcess>),
Ready(Arc<RunningService<RoleClient, ClientInfo>>),
Closed,
}
/// A test client over a stdio MCP server.
pub struct McpStdioTestClient {
server_name: String,
state: Mutex<State>,
}
impl McpStdioTestClient {
/// Spawns the server `config` names. Only a `stdio` transport is
/// supported; call [`initialize`](Self::initialize) next.
pub fn new(config: &McpServerSettings) -> Result<Self> {
let McpTransport::Stdio { command, env } = &config.transport else {
return Err(anyhow!(
"MCP test client '{}': only a stdio transport is supported",
config.name
));
};
let (program, args) = command
.split_first()
.ok_or_else(|| anyhow!("MCP server '{}': command must not be empty", config.name))?;
let mut cmd = Command::new(program);
cmd.args(args)
.stdin(Stdio::piped())
.stdout(Stdio::piped())
.stderr(Stdio::piped())
.kill_on_drop(true);
if config.clear_env {
cmd.env_clear();
}
if !env.is_empty() {
cmd.envs(env);
}
if let Some(current_dir) = config.current_dir.as_ref() {
cmd.current_dir(current_dir);
}
#[cfg(unix)]
cmd.process_group(0);
let transport = TokioChildProcess::new(cmd)
.with_context(|| format!("failed to spawn MCP server '{}'", config.name))?;
Ok(Self {
server_name: config.name.clone(),
state: Mutex::new(State::Connecting(Some(transport))),
})
}
/// Performs the MCP handshake within `timeout`.
pub async fn initialize(&self, timeout: Duration) -> Result<()> {
let transport = {
let mut guard = self.state.lock().await;
match &mut *guard {
State::Connecting(transport) => transport
.take()
.ok_or_else(|| anyhow!("client already initializing"))?,
State::Ready(_) => return Err(anyhow!("client already initialized")),
State::Closed => return Err(anyhow!("MCP client is shut down")),
}
};
let info = ClientInfo::new(
ClientCapabilities::default(),
Implementation::new("fabro-mcp-test", env!("CARGO_PKG_VERSION")),
)
.with_protocol_version(ProtocolVersion::V_2025_03_26);
let service = time::timeout(timeout, serve_client(info, transport))
.await
.map_err(|_| {
anyhow!(
"timed out initializing MCP server '{}' after {timeout:?}",
self.server_name
)
})?
.map_err(|error| {
anyhow!(
"failed to initialize MCP server '{}': {error}",
self.server_name
)
})?;
if let Some(peer) = service.peer().peer_info() {
tracing::info!(
server = %self.server_name,
server_name = %peer.server_info.name,
server_version = %peer.server_info.version,
"MCP server initialized"
);
}
*self.state.lock().await = State::Ready(Arc::new(service));
Ok(())
}
/// Every tool the server exposes, as `(name, description, input_schema)`.
pub async fn list_tools(&self) -> Result<Vec<(String, String, serde_json::Value)>> {
let service = self.service().await?;
let tools = service.list_all_tools().await.map_err(|error| {
anyhow!(
"failed to list tools from MCP server '{}': {error}",
self.server_name
)
})?;
Ok(tools
.into_iter()
.map(|tool| {
(
tool.name.to_string(),
tool.description.as_deref().unwrap_or("").to_string(),
serde_json::to_value(&*tool.input_schema).unwrap_or_default(),
)
})
.collect())
}
/// Calls `name` with `arguments`, waiting at most `timeout`.
pub async fn call_tool(
&self,
name: &str,
arguments: serde_json::Value,
timeout: Duration,
) -> Result<CallToolResult> {
let service = self.service().await?;
let mut params = CallToolRequestParams::new(name.to_string());
match arguments {
serde_json::Value::Object(map) => params = params.with_arguments(map),
serde_json::Value::Null => {}
other => {
return Err(anyhow!(
"MCP tool arguments must be a JSON object, got {other}"
));
}
}
time::timeout(timeout, service.call_tool(params))
.await
.map_err(|_| {
anyhow!(
"timed out calling tool '{name}' on MCP server '{}' after {timeout:?}",
self.server_name
)
})?
.map_err(|error| {
anyhow!(
"failed to call tool '{name}' on MCP server '{}': {error}",
self.server_name
)
})
}
/// Ends the session and stops the server.
pub async fn shutdown(self) -> Result<()> {
let service = match std::mem::replace(&mut *self.state.lock().await, State::Closed) {
State::Connecting(_) | State::Closed => None,
State::Ready(service) => Some(service),
};
if let Some(service) = service {
match Arc::try_unwrap(service) {
Ok(mut service) => {
service
.close_with_timeout(Duration::from_secs(2))
.await
.context("failed to shut down MCP client")?;
}
Err(service) => service.cancellation_token().cancel(),
}
}
Ok(())
}
async fn service(&self) -> Result<Arc<RunningService<RoleClient, ClientInfo>>> {
match &*self.state.lock().await {
State::Ready(service) => Ok(Arc::clone(service)),
State::Connecting(_) => Err(anyhow!("MCP client not initialized")),
State::Closed => Err(anyhow!("MCP client is shut down")),
}
}
}

542
lib/components/fabro-mcp/tests/stdio_integration.rs
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@ -1,542 +0,0 @@
use std::collections::HashMap;
use std::convert::Infallible;
use std::sync::Arc;
use std::time::Duration;
use axum::body::{Body, Bytes};
use axum::extract::{Query, State};
use axum::http::{HeaderMap, StatusCode, header};
use axum::response::Response;
use axum::routing::get;
use axum::{Json, Router};
use fabro_mcp::client::McpClient;
use fabro_mcp::config::{McpHttpProtocol, McpServerSettings, McpTransport};
use fabro_mcp::connection_manager::{McpConnectionManager, call_result_to_string};
use fabro_mcp::http_transport::sandbox_mcp_http_url;
use futures::{StreamExt as _, stream};
use serde_json::Value;
use tokio::net::TcpListener;
use tokio::sync::{Mutex, mpsc};
use tokio_stream::wrappers::ReceiverStream;
fn test_server_config() -> McpServerSettings {
let test_server = format!("{}/tests/test_mcp_server.py", env!("CARGO_MANIFEST_DIR"));
McpServerSettings {
name: "test-echo".into(),
transport: McpTransport::Stdio {
command: vec!["python3".into(), test_server],
env: HashMap::new(),
},
current_dir: None,
clear_env: false,
startup_timeout_secs: 10,
tool_timeout_secs: 30,
}
}
#[tokio::test]
async fn stdio_client_initialize_and_list_tools() {
let config = test_server_config();
let client = McpClient::new(&config).unwrap();
client.initialize(config.startup_timeout()).await.unwrap();
let tools = client.list_tools().await.unwrap();
assert_eq!(tools.len(), 1);
assert_eq!(tools[0].0, "echo");
assert_eq!(tools[0].1, "Echo back the message");
}
#[tokio::test]
#[expect(
clippy::disallowed_methods,
reason = "stdio integration test stages a local process cwd and inherits PATH for python3 lookup"
)]
async fn stdio_client_uses_configured_cwd_and_exact_env() {
let test_server = format!("{}/tests/test_mcp_server.py", env!("CARGO_MANIFEST_DIR"));
let temp_dir = std::env::temp_dir().join(format!(
"fabro-mcp-stdio-{}-{}",
std::process::id(),
std::time::SystemTime::now()
.duration_since(std::time::UNIX_EPOCH)
.unwrap()
.as_nanos()
));
std::fs::create_dir(&temp_dir).unwrap();
let canonical_temp_dir = std::fs::canonicalize(&temp_dir).unwrap();
let mut env = HashMap::new();
env.insert(
"PATH".to_string(),
std::env::var("PATH").expect("PATH should be set for python3 lookup"),
);
env.insert("FABRO_MCP_TEST_SENTINEL".to_string(), "fixture".to_string());
let config = McpServerSettings {
name: "test-echo".into(),
transport: McpTransport::Stdio {
command: vec!["python3".into(), test_server],
env,
},
current_dir: Some(canonical_temp_dir.clone()),
clear_env: true,
startup_timeout_secs: 10,
tool_timeout_secs: 30,
};
let client = McpClient::new(&config).unwrap();
client.initialize(config.startup_timeout()).await.unwrap();
let cwd = client
.call_tool(
"echo",
serde_json::json!({"message": "__cwd__"}),
Duration::from_secs(5),
)
.await
.unwrap();
assert_eq!(
call_result_to_string(&cwd).unwrap(),
canonical_temp_dir.display().to_string()
);
let sentinel = client
.call_tool(
"echo",
serde_json::json!({"message": "__env:FABRO_MCP_TEST_SENTINEL__"}),
Duration::from_secs(5),
)
.await
.unwrap();
assert_eq!(call_result_to_string(&sentinel).unwrap(), "fixture");
let home = client
.call_tool(
"echo",
serde_json::json!({"message": "__env:HOME__"}),
Duration::from_secs(5),
)
.await
.unwrap();
assert_eq!(call_result_to_string(&home).unwrap(), "");
client.shutdown().await.unwrap();
std::fs::remove_dir(&temp_dir).unwrap();
}
#[tokio::test]
async fn stdio_client_call_tool_echo() {
let config = test_server_config();
let client = McpClient::new(&config).unwrap();
client.initialize(config.startup_timeout()).await.unwrap();
let result = client
.call_tool(
"echo",
serde_json::json!({"message": "hello from rust"}),
Duration::from_secs(10),
)
.await
.unwrap();
let text = call_result_to_string(&result).unwrap();
assert_eq!(text, "hello from rust");
}
#[tokio::test]
async fn connection_manager_stdio_roundtrip() {
let config = test_server_config();
let mut mgr = McpConnectionManager::new();
let results = mgr.start_servers(&[config]).await;
assert_eq!(results.len(), 1);
let (name, tool_count) = &results[0];
assert_eq!(name, "test-echo");
assert_eq!(*tool_count.as_ref().unwrap(), 1);
let tools = mgr.all_tools();
assert!(tools.contains_key("mcp__test_echo__echo"));
let result = mgr
.call_tool(
"mcp__test_echo__echo",
serde_json::json!({"message": "roundtrip"}),
)
.await
.unwrap();
let text = call_result_to_string(&result).unwrap();
assert_eq!(text, "roundtrip");
}
#[tokio::test]
async fn connection_manager_call_tool_uses_configured_tool_timeout() {
let mut config = test_server_config();
config.tool_timeout_secs = 1;
let mut mgr = McpConnectionManager::new();
let results = mgr.start_servers(&[config]).await;
assert_eq!(results.len(), 1);
assert!(
results[0].1.is_ok(),
"server should start: {:?}",
results[0]
);
let err = mgr
.call_tool(
"mcp__test_echo__echo",
serde_json::json!({"message": "__sleep_ms:1500__"}),
)
.await
.unwrap_err();
assert!(
err.to_string()
.contains("timed out calling tool 'echo' on MCP server 'test-echo'"),
"unexpected error: {err}"
);
}
#[tokio::test]
async fn sse_client_initialize_and_call_tool() {
#[derive(Clone)]
struct SseState {
messages: Arc<Mutex<HashMap<String, mpsc::Sender<String>>>>,
}
async fn sse(State(state): State<SseState>) -> Response {
let session_id = "session-1".to_string();
let (tx, rx) = mpsc::channel::<String>(16);
state.messages.lock().await.insert(session_id.clone(), tx);
let endpoint = format!("event: endpoint\ndata: /sse?sessionId={session_id}\n\n");
let body = Body::from_stream(
stream::once(async move { Ok::<_, Infallible>(Bytes::from(endpoint)) }).chain(
ReceiverStream::new(rx).map(|event| Ok::<_, Infallible>(Bytes::from(event))),
),
);
Response::builder()
.header(header::CONTENT_TYPE, "text/event-stream")
.body(body)
.unwrap()
}
async fn post_sse(
State(state): State<SseState>,
Query(query): Query<HashMap<String, String>>,
headers: HeaderMap,
Json(message): Json<Value>,
) -> StatusCode {
assert_eq!(
headers
.get("x-test-token")
.and_then(|value| value.to_str().ok()),
Some("secret")
);
let session_id = query.get("sessionId").expect("sessionId query").clone();
let sender = state
.messages
.lock()
.await
.get(&session_id)
.cloned()
.expect("active SSE stream");
let Some(id) = message.get("id").cloned() else {
return StatusCode::ACCEPTED;
};
let method = message.get("method").and_then(Value::as_str).unwrap_or("");
let result = match method {
"initialize" => serde_json::json!({
"protocolVersion": "2024-11-05",
"capabilities": {"tools": {}},
"serverInfo": {"name": "legacy-sse-test", "version": "1.0.0"}
}),
"tools/list" => serde_json::json!({
"tools": [{
"name": "echo",
"description": "Echo back the message",
"inputSchema": {
"type": "object",
"properties": {"message": {"type": "string"}},
"required": ["message"]
}
}]
}),
"tools/call" => serde_json::json!({
"content": [{"type": "text", "text": "hello from sse"}],
"isError": false
}),
_ => serde_json::json!({}),
};
let response = serde_json::json!({"jsonrpc": "2.0", "id": id, "result": result});
sender
.send(format!("data: {response}\n\n"))
.await
.expect("SSE stream should be open");
StatusCode::ACCEPTED
}
let state = SseState {
messages: Arc::new(Mutex::new(HashMap::new())),
};
let app = Router::new()
.route("/sse", get(sse).post(post_sse))
.with_state(state);
let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
let addr = listener.local_addr().unwrap();
tokio::spawn(async move {
axum::serve(listener, app).await.unwrap();
});
let config = McpServerSettings {
name: "test-sse".into(),
transport: McpTransport::Http {
protocol: McpHttpProtocol::Sse,
url: format!("http://{addr}/sse"),
headers: HashMap::from([("x-test-token".to_string(), "secret".to_string())]),
},
current_dir: None,
clear_env: false,
startup_timeout_secs: 10,
tool_timeout_secs: 30,
};
let client = McpClient::new(&config).unwrap();
client.initialize(config.startup_timeout()).await.unwrap();
let tools = client.list_tools().await.unwrap();
assert_eq!(tools[0].0, "echo");
let result = client
.call_tool(
"echo",
serde_json::json!({"message": "hello"}),
Duration::from_secs(5),
)
.await
.unwrap();
assert_eq!(call_result_to_string(&result).unwrap(), "hello from sse");
}
#[tokio::test]
async fn sse_client_rejects_oversized_messages() {
#[derive(Clone)]
struct SseState {
messages: Arc<Mutex<HashMap<String, mpsc::Sender<String>>>>,
}
async fn sse(State(state): State<SseState>) -> Response {
let session_id = "oversized-session".to_string();
let (tx, rx) = mpsc::channel::<String>(16);
state.messages.lock().await.insert(session_id.clone(), tx);
let endpoint = format!("event: endpoint\ndata: /sse?sessionId={session_id}\n\n");
let body = Body::from_stream(
stream::once(async move { Ok::<_, Infallible>(Bytes::from(endpoint)) }).chain(
ReceiverStream::new(rx).map(|event| Ok::<_, Infallible>(Bytes::from(event))),
),
);
Response::builder()
.header(header::CONTENT_TYPE, "text/event-stream")
.body(body)
.unwrap()
}
async fn post_sse(
State(state): State<SseState>,
Query(query): Query<HashMap<String, String>>,
Json(message): Json<Value>,
) -> StatusCode {
let session_id = query.get("sessionId").expect("sessionId query").clone();
let sender = state
.messages
.lock()
.await
.get(&session_id)
.cloned()
.expect("active SSE stream");
let Some(id) = message.get("id").cloned() else {
return StatusCode::ACCEPTED;
};
let oversized_name = "x".repeat(1024 * 1024 + 1);
let response = serde_json::json!({
"jsonrpc": "2.0",
"id": id,
"result": {
"protocolVersion": "2024-11-05",
"capabilities": {"tools": {}},
"serverInfo": {"name": oversized_name, "version": "1.0.0"}
}
});
sender
.send(format!("data: {response}\n\n"))
.await
.expect("SSE stream should be open");
StatusCode::ACCEPTED
}
let state = SseState {
messages: Arc::new(Mutex::new(HashMap::new())),
};
let app = Router::new()
.route("/sse", get(sse).post(post_sse))
.with_state(state);
let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
let addr = listener.local_addr().unwrap();
tokio::spawn(async move {
axum::serve(listener, app).await.unwrap();
});
let config = McpServerSettings {
name: "test-sse".into(),
transport: McpTransport::Http {
protocol: McpHttpProtocol::Sse,
url: format!("http://{addr}/sse"),
headers: HashMap::new(),
},
current_dir: None,
clear_env: false,
startup_timeout_secs: 2,
tool_timeout_secs: 30,
};
let client = McpClient::new(&config).unwrap();
let error = client
.initialize(config.startup_timeout())
.await
.expect_err("oversized SSE message should fail initialization");
let error = error.to_string();
assert!(
error.contains("connection closed"),
"unexpected error: {error}"
);
assert!(
!error.contains("xxxxxxxx"),
"oversized payload leaked: {error}"
);
}
#[tokio::test]
async fn sse_client_rejects_cross_origin_endpoint() {
use std::sync::atomic::{AtomicUsize, Ordering};
use axum::routing::post;
#[derive(Clone)]
struct EvilState {
hits: Arc<AtomicUsize>,
}
async fn evil_post(State(state): State<EvilState>) -> StatusCode {
state.hits.fetch_add(1, Ordering::SeqCst);
StatusCode::ACCEPTED
}
#[derive(Clone)]
struct VictimState {
endpoint: String,
}
async fn sse(State(state): State<VictimState>) -> Response {
let body = Body::from_stream(stream::once(async move {
Ok::<_, Infallible>(Bytes::from(format!(
"event: endpoint\ndata: {endpoint}\n\n",
endpoint = state.endpoint
)))
}));
Response::builder()
.header(header::CONTENT_TYPE, "text/event-stream")
.body(body)
.unwrap()
}
let evil_state = EvilState {
hits: Arc::new(AtomicUsize::new(0)),
};
let evil_app = Router::new()
.route("/steal", post(evil_post))
.with_state(evil_state.clone());
let evil_listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
let evil_addr = evil_listener.local_addr().unwrap();
tokio::spawn(async move {
axum::serve(evil_listener, evil_app).await.unwrap();
});
let victim_state = VictimState {
endpoint: format!("http://127.0.0.1:{}/steal", evil_addr.port()),
};
let victim_app = Router::new()
.route("/sse", get(sse))
.with_state(victim_state);
let victim_listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
let victim_addr = victim_listener.local_addr().unwrap();
tokio::spawn(async move {
axum::serve(victim_listener, victim_app).await.unwrap();
});
let config = McpServerSettings {
name: "test-sse".into(),
transport: McpTransport::Http {
protocol: McpHttpProtocol::Sse,
url: format!("http://{victim_addr}/sse"),
headers: HashMap::from([("authorization".to_string(), "Bearer secret".to_string())]),
},
current_dir: None,
clear_env: false,
startup_timeout_secs: 2,
tool_timeout_secs: 30,
};
let client = McpClient::new(&config).unwrap();
client
.initialize(config.startup_timeout())
.await
.expect_err("cross-origin SSE endpoint should fail initialization");
assert_eq!(
evil_state.hits.load(Ordering::SeqCst),
0,
"client must not POST to a cross-origin endpoint advertised by the SSE server"
);
}
#[test]
fn sandbox_mcp_http_url_builds_sse_endpoint_under_preview_path() {
let url = sandbox_mcp_http_url(
McpHttpProtocol::Sse,
"https://preview.example.com/proxy/3100/",
)
.unwrap();
assert_eq!(url, "https://preview.example.com/proxy/3100/sse");
}
#[test]
fn sandbox_mcp_http_url_leaves_streamable_http_preview_url_unchanged() {
let url = sandbox_mcp_http_url(
McpHttpProtocol::StreamableHttp,
"https://preview.example.com/proxy/3100/mcp",
)
.unwrap();
assert_eq!(url, "https://preview.example.com/proxy/3100/mcp");
}
#[test]
fn sandbox_mcp_http_url_preserves_query_and_path_without_trailing_slash() {
let url = sandbox_mcp_http_url(
McpHttpProtocol::Sse,
"https://preview.example.com/proxy/3100?token=abc",
)
.unwrap();
assert_eq!(url, "https://preview.example.com/proxy/3100/sse?token=abc");
}
#[tokio::test]
async fn connection_manager_exposes_tools_as_coding_agent_tools() {
use pebble_coding_agent::tools::ToolSource;
let mut mgr = McpConnectionManager::new();
mgr.start_servers(&[test_server_config()]).await;
let mgr = std::sync::Arc::new(mgr);
let tools = mgr.tools();
assert_eq!(tools.len(), 1);
let tool = &tools[0];
assert_eq!(tool.definition().name, "mcp__test_echo__echo");
assert_eq!(tool.source(), &ToolSource::Mcp {
server_name: "test-echo".to_string(),
original_name: "echo".to_string(),
});
}

48
lib/components/fabro-sandbox/src/driver_sandbox.rs
View file

@ -23,9 +23,10 @@ use fabro_github::token_source::InstallationTokenSource;
use fabro_types::SandboxProviderKind;
use fabro_util::workspace_glob::WorkspaceGlob;
use sandbox_driver::{
DirEntry, EventContext, FileKind, GrepMatch, GrepOptions, LifecycleTimers, PtyOptions, PtySize,
Sandbox as DriverHandle, SandboxProvider as DriverProvider, SandboxSource,
SandboxSpec as DriverSpec, SandboxState, Search as _, WaitOptions, WalkOptions,
Capability, DirEntry, EventContext, FileKind, GrepMatch, GrepOptions, LifecycleTimers,
PreviewUrl, PreviewUrls, PtyOptions, PtySize, Sandbox as DriverHandle,
SandboxProvider as DriverProvider, SandboxSource, SandboxSpec as DriverSpec, SandboxState,
Search as _, WaitOptions, WalkOptions,
};
use sandbox_driver_host::HostProvider;
use tokio::fs;
@ -1151,6 +1152,16 @@ impl RunSandbox {
.map_err(|error| crate::Error::context("Failed to build sandbox shell command", error))
}
/// The route from fabro to a port inside the sandbox, as pebble's MCP
/// support takes it: the driver's preview URLs, when the provider has
/// them. `None` for a provider without forwarding, which is where pebble
/// reaches the port on the loopback address instead.
#[must_use]
pub fn port_routes(self: &Arc<Self>) -> Option<Arc<dyn PreviewUrls>> {
self.handle().ok()?.preview_urls()?;
Some(Arc::new(SandboxPortRoutes(Arc::clone(self))))
}
pub async fn get_preview_url(
&self,
port: u16,
@ -1169,6 +1180,37 @@ impl RunSandbox {
}
}
/// [`PreviewUrls`] over a run sandbox's driver handle, for pebble.
struct SandboxPortRoutes(Arc<RunSandbox>);
impl SandboxPortRoutes {
/// The driver's facet, present whenever [`RunSandbox::port_routes`] handed
/// this out: the handle is set once and never cleared.
fn facet(&self) -> Option<&dyn PreviewUrls> {
self.0
.handle()
.ok()
.and_then(|handle| handle.preview_urls())
}
}
#[async_trait::async_trait]
impl PreviewUrls for SandboxPortRoutes {
async fn preview_url(&self, port: u16) -> sandbox_driver::Result<PreviewUrl> {
match self.facet() {
Some(facet) => facet.preview_url(port).await,
None => Err(sandbox_driver::Error::unsupported(Capability::PreviewUrls)),
}
}
async fn release_preview_url(&self, port: u16) -> sandbox_driver::Result<()> {
match self.facet() {
Some(facet) => facet.release_preview_url(port).await,
None => Err(sandbox_driver::Error::unsupported(Capability::PreviewUrls)),
}
}
}
impl RunSandbox {
fn repo_cloned(&self) -> bool {
self.workspace

1
lib/components/fabro-workflow/Cargo.toml
View file

@ -89,6 +89,7 @@ fabro-environment = { path = "../fabro-environment" }
fabro-sandbox = { path = "../fabro-sandbox", features = ["test-support"] }
fabro-mcp = { path = "../fabro-mcp" }
tokio = { workspace = true, features = ["test-util", "macros"] }
pebble-coding-agent = { workspace = true, features = ["test-util"] }
object_store.workspace = true
assert_cmd = "2"
predicates = "3"

1
lib/components/fabro-workflow/src/handler/llm/mod.rs
View file

@ -8,7 +8,6 @@ pub mod pebble;
pub mod preamble;
pub mod router;
pub mod routing;
mod sandbox_mcp;
pub use acp::AgentAcpBackend;
pub use controls::EffectiveRequestControls;

172
lib/components/fabro-workflow/src/handler/llm/pebble.rs
View file

@ -20,12 +20,12 @@ use fabro_llm::lithos_catalog::Catalog;
use fabro_llm::types::ResponseFormat;
use fabro_llm::{Client, ClientOptions, Request, Response};
use fabro_mcp::config::McpServerSettings;
use fabro_mcp::connection_manager::McpConnectionManager;
use fabro_mcp::pebble::pebble_servers;
use fabro_sandbox::{RunSandbox, SecretRedactor};
use fabro_types::settings::run::RunModelControls;
use fabro_types::{
AgentProfileKind, ModelRef, PermissionLevel, Principal, SessionCapability, StageId,
StageTiming, UsdMicros, billing,
AgentMcpToolSummary, AgentProfileKind, ModelRef, PermissionLevel, Principal, SessionCapability,
StageId, StageTiming, UsdMicros, billing,
};
use fabro_util::home::Home;
use lithos_llm::catalog::{ModelId, ProviderId};
@ -58,7 +58,6 @@ use super::controls::{
use super::fabro_tools::register_fabro_run_tools;
use super::fallback::{self, FallbackPlan, LlmRoute};
use super::routing::{self, ProviderContext};
use super::sandbox_mcp::{self, McpServerOutcome};
use crate::agent_memory;
use crate::context::WorkflowContext;
use crate::context::keys::Fidelity;
@ -100,11 +99,12 @@ pub struct PebbleBackend {
fabro_run_tools: Option<FabroRunToolServices>,
}
/// A conversation between stages: what the next stage resumes from.
/// A conversation between stages: what the next stage resumes from. The
/// successor starts the stage's MCP servers again; the same settings give
/// the same tool names, so the conversation's earlier calls stay valid.
struct CachedThread {
export: CodingAgentExport,
fallback_plan: FallbackPlan,
mcp: Option<Arc<McpConnectionManager>>,
}
/// How the backend reports a failed prompt.
@ -165,8 +165,10 @@ fn classify_agent_error(error: pebble_coding_agent::Error) -> AgentErrorDisposit
// --- Event sink -----------------------------------------------------------
/// Pebble's durable event sink for one stage: every agent event becomes a
/// run event in the run's log before the agent goes on, and a route failover
/// is mirrored as the run's own `agent.failover` event on the way.
/// run event in the run's log before the agent goes on. A route failover and
/// an MCP server's outcome are facts the run already has events for, so
/// those are mirrored onto the run's own `agent.failover`, `agent.mcp.ready`,
/// and `agent.mcp.failed` events instead of being stored twice.
struct WorkflowEventSink {
emitter: Arc<Emitter>,
node_id: String,
@ -182,20 +184,54 @@ impl EventSink for WorkflowEventSink {
// Every event, including streaming deltas, resets the run's activity
// watchdog.
self.emitter.touch();
if let CodingEvent::RouteFailover {
from,
to,
attempt,
error,
} = &event.event
{
self.emitter.emit_scoped(
&Event::Failover {
stage: self.node_id.clone(),
props: self.plan.failover_props(from, to, *attempt, &error.message),
},
&self.scope,
);
match &event.event {
CodingEvent::RouteFailover {
from,
to,
attempt,
error,
} => {
self.emitter.emit_scoped(
&Event::Failover {
stage: self.node_id.clone(),
props: self.plan.failover_props(from, to, *attempt, &error.message),
},
&self.scope,
);
return Ok(());
}
CodingEvent::McpServerReady { server, tools } => {
self.emitter.emit_scoped(
&Event::AgentMcpReady {
node_id: self.node_id.clone(),
visit: self.scope.visit,
server_name: server.clone(),
tool_count: tools.len(),
tools: tools
.iter()
.map(|tool| AgentMcpToolSummary {
name: tool.name.clone(),
original_name: tool.original_name.clone(),
})
.collect(),
},
&self.scope,
);
return Ok(());
}
CodingEvent::McpServerFailed { server, error } => {
self.emitter.emit_scoped(
&Event::AgentMcpFailed {
node_id: self.node_id.clone(),
visit: self.scope.visit,
server_name: server.clone(),
error: error.clone(),
},
&self.scope,
);
return Ok(());
}
_ => {}
}
// Deltas and the prompt's own durability barrier are not run history.
if event.event.is_streaming_noise() || matches!(event.event, CodingEvent::ProcessingEnd) {
@ -329,7 +365,6 @@ struct LiveAgent {
agent: CodingAgent,
handle: Arc<PebbleControlHandle>,
lease: Option<Arc<ActivationLease>>,
mcp: Option<Arc<McpConnectionManager>>,
total_usage: TokenCounts,
total_cost: Option<UsdMicros>,
inference_duration: Duration,
@ -341,16 +376,11 @@ struct LiveAgent {
}
impl LiveAgent {
fn new(
agent: CodingAgent,
handle: Arc<PebbleControlHandle>,
mcp: Option<Arc<McpConnectionManager>>,
) -> Self {
fn new(agent: CodingAgent, handle: Arc<PebbleControlHandle>) -> Self {
Self {
agent,
handle,
lease: None,
mcp,
total_usage: TokenCounts::default(),
total_cost: None,
inference_duration: Duration::ZERO,
@ -594,49 +624,13 @@ impl PebbleBackend {
.with_compaction_preserve_turns(COMPACTION_PRESERVE_TURNS)
}
/// Start the stage's MCP servers, reporting each as a run event.
async fn start_mcp(
&self,
bindings: &StageBindings<'_>,
cancel_token: &CancellationToken,
) -> Result<Option<Arc<McpConnectionManager>>, Error> {
if self.mcp_servers.is_empty() {
return Ok(None);
/// The application tools a stage agent gets beyond pebble's own and the
/// MCP servers'.
fn stage_tools(&self) -> Vec<RegisteredTool> {
match &self.fabro_run_tools {
Some(services) => register_fabro_run_tools(services),
None => Vec::new(),
}
let startup =
sandbox_mcp::start_mcp_servers(bindings.sandbox, &self.mcp_servers, cancel_token)
.await?;
for (server_name, outcome) in startup.outcomes {
let event = match outcome {
McpServerOutcome::Ready { tool_count, tools } => Event::AgentMcpReady {
node_id: bindings.node_id.to_string(),
visit: bindings.stage_scope.visit,
server_name,
tool_count,
tools,
},
McpServerOutcome::Failed { error } => Event::AgentMcpFailed {
node_id: bindings.node_id.to_string(),
visit: bindings.stage_scope.visit,
server_name,
error,
},
};
bindings.emitter.emit_scoped(&event, bindings.stage_scope);
}
Ok(Some(startup.manager))
}
/// The application tools a stage agent gets beyond pebble's own.
fn stage_tools(&self, mcp: Option<&Arc<McpConnectionManager>>) -> Vec<RegisteredTool> {
let mut tools = Vec::new();
if let Some(services) = &self.fabro_run_tools {
tools.extend(register_fabro_run_tools(services));
}
if let Some(manager) = mcp {
tools.extend(manager.tools());
}
tools
}
/// Bind the stage's services, the plan's current route, and the routes
@ -648,12 +642,12 @@ impl PebbleBackend {
plan: &FallbackPlan,
provider: &ProviderContext,
bindings: &StageBindings<'_>,
mcp: Option<&Arc<McpConnectionManager>>,
) -> CodingAgentBuilder {
let route = plan.current();
let max_tokens = node_max_output_tokens(node).map(i64::from);
builder = builder
.tools(self.stage_tools(mcp))
.tools(self.stage_tools())
.mcp_servers(pebble_servers(&self.mcp_servers))
.permission_level(PermissionLevel::Full)
.options(self.agent_options(
node,
@ -670,6 +664,9 @@ impl PebbleBackend {
}))
.redactor(Arc::new(SecretRedactor))
.subagents(SubagentOptions::enabled());
if let Some(routes) = bindings.sandbox.port_routes() {
builder = builder.port_routes(routes);
}
if let Some(provider) = &self.tool_env {
builder = builder.tool_env_provider(Arc::clone(provider));
}
@ -695,13 +692,12 @@ impl PebbleBackend {
plan: &FallbackPlan,
provider: &ProviderContext,
bindings: &StageBindings<'_>,
mcp: Option<&Arc<McpConnectionManager>>,
) -> Result<CodingAgent, Error> {
let client = self.build_llm_client().await?;
let environment: Arc<dyn Environment> =
Arc::clone(bindings.sandbox) as Arc<dyn Environment>;
let builder = CodingAgent::builder(client, environment).model(plan.current().selector());
self.bind_builder(builder, node, plan, provider, bindings, mcp)
self.bind_builder(builder, node, plan, provider, bindings)
.build()
.await
.map_err(|error| Error::handler_with_source("Failed to start agent session", error))
@ -716,13 +712,12 @@ impl PebbleBackend {
plan: &FallbackPlan,
provider: &ProviderContext,
bindings: &StageBindings<'_>,
mcp: Option<&Arc<McpConnectionManager>>,
) -> Result<CodingAgent, Error> {
let client = self.build_llm_client().await?;
let environment: Arc<dyn Environment> =
Arc::clone(bindings.sandbox) as Arc<dyn Environment>;
let builder = CodingAgent::resume_from_export(client, environment, export);
self.bind_builder(builder, node, plan, provider, bindings, mcp)
self.bind_builder(builder, node, plan, provider, bindings)
.build()
.await
.map_err(|error| Error::handler_with_source("Failed to resume agent session", error))
@ -950,8 +945,8 @@ async fn build_llm_client(
#[async_trait]
impl CodergenBackend for PebbleBackend {
async fn shutdown(&self, _emitter: &Arc<Emitter>) {
// Exported conversations were shut down when their stages ended; the
// MCP connections they kept alive close with the exports.
// Exported conversations were shut down when their stages ended, and
// their MCP servers with them.
self.threads
.lock()
.unwrap_or_else(std::sync::PoisonError::into_inner)
@ -1092,7 +1087,7 @@ impl CodergenBackend for PebbleBackend {
let cached = reuse_key.as_ref().and_then(|key| self.take_thread(key));
let is_reused = cached.is_some();
let (agent, mut fallback_plan, mcp) = if let Some(thread) = cached {
let (agent, mut fallback_plan) = if let Some(thread) = cached {
let route = thread.fallback_plan.current().clone();
let provider = self.resolve_provider_context(
route.target.model.as_str(),
@ -1105,10 +1100,9 @@ impl CodergenBackend for PebbleBackend {
&thread.fallback_plan,
&provider,
&bindings,
thread.mcp.as_ref(),
)
.await?;
(agent, thread.fallback_plan, thread.mcp)
(agent, thread.fallback_plan)
} else {
let model = node.model().unwrap_or(&self.model);
let provider = routing::resolve_node_provider_context(
@ -1126,17 +1120,10 @@ impl CodergenBackend for PebbleBackend {
route.target.model.as_str(),
Some(route.target.provider.as_str()),
)?;
let mcp = self.start_mcp(&bindings, cancel_token).await?;
let agent = self
.build_agent(
node,
&fallback_plan,
&route_provider,
&bindings,
mcp.as_ref(),
)
.build_agent(node, &fallback_plan, &route_provider, &bindings)
.await?;
(agent, fallback_plan, mcp)
(agent, fallback_plan)
};
if cancel_token.is_cancelled() {
let mut agent = agent;
@ -1152,7 +1139,7 @@ impl CodergenBackend for PebbleBackend {
);
let handle = Arc::new(PebbleControlHandle::new(agent.control_handle()));
let mut live = LiveAgent::new(agent, handle, mcp);
let mut live = LiveAgent::new(agent, handle);
let route = fallback_plan.current().clone();
if let Err(error) =
self.activate(&mut live, &route, &stage_id, request.thread_id, &bindings)
@ -1267,7 +1254,6 @@ impl CodergenBackend for PebbleBackend {
self.store_thread(key, CachedThread {
export: export.clone(),
fallback_plan: fallback_plan.clone(),
mcp: live.mcp.clone(),
});
}

302
lib/components/fabro-workflow/src/handler/llm/sandbox_mcp.rs
View file

@ -1,302 +0,0 @@
//! MCP servers for a workflow agent stage.
//!
//! `McpTransport::Sandbox` servers start inside the run sandbox and are
//! reached over HTTP through the sandbox's preview URL; every other transport
//! is connected as configured. The outcome of each server is reported back so
//! the stage can record it as a run event.
use std::collections::HashMap;
use std::sync::Arc;
use fabro_mcp::config::{McpServerSettings, McpTransport};
use fabro_mcp::connection_manager::McpConnectionManager;
use fabro_mcp::http_transport;
use fabro_sandbox::{RunSandbox, shell_quote};
use fabro_types::AgentMcpToolSummary;
use fabro_util::shell::shell_join;
use tokio_util::sync::CancellationToken;
use tracing::{info, warn};
use crate::error::Error;
/// What became of one configured MCP server.
pub(crate) enum McpServerOutcome {
Ready {
tool_count: usize,
tools: Vec<AgentMcpToolSummary>,
},
Failed {
error: String,
},
}
pub(crate) struct McpStartup {
pub(crate) manager: Arc<McpConnectionManager>,
/// One entry per configured server, in configuration order.
pub(crate) outcomes: Vec<(String, McpServerOutcome)>,
}
/// Start every configured server and connect to it.
///
/// # Errors
///
/// Returns [`Error::Cancelled`] when `cancel_token` fires; a server that
/// fails to start or connect is reported in the outcomes instead.
pub(crate) async fn start_mcp_servers(
sandbox: &RunSandbox,
servers: &[McpServerSettings],
cancel_token: &CancellationToken,
) -> Result<McpStartup, Error> {
let mut outcomes = Vec::with_capacity(servers.len());
let mut resolved = Vec::with_capacity(servers.len());
for config in servers {
if cancel_token.is_cancelled() {
return Err(Error::Cancelled);
}
match &config.transport {
McpTransport::Sandbox {
protocol,
command,
port,
env,
} => {
match start_sandbox_mcp_server(sandbox, command, *port, env, cancel_token).await? {
Ok((url, headers)) => {
match http_transport::sandbox_mcp_http_url(*protocol, &url) {
Ok(url) => {
info!(
server = %config.name,
url = %url,
"Sandbox MCP server started, connecting via HTTP"
);
resolved.push(McpServerSettings {
name: config.name.clone(),
transport: McpTransport::Http {
protocol: *protocol,
url,
headers,
},
current_dir: config.current_dir.clone(),
clear_env: config.clear_env,
startup_timeout_secs: config.startup_timeout_secs,
tool_timeout_secs: config.tool_timeout_secs,
});
}
Err(error) => {
outcomes.push((config.name.clone(), McpServerOutcome::Failed {
error: error.to_string(),
}));
}
}
}
Err(error) => {
warn!(server = %config.name, error = %error, "Failed to start sandbox MCP server");
outcomes.push((config.name.clone(), McpServerOutcome::Failed { error }));
}
}
}
_ => resolved.push(config.clone()),
}
}
let mut manager = McpConnectionManager::new();
for (server_name, result) in manager.start_servers(&resolved).await {
let outcome = match result {
Ok(tool_count) => McpServerOutcome::Ready {
tool_count,
tools: manager
.tool_summaries_for_server(&server_name)
.into_iter()
.map(|(name, original_name)| AgentMcpToolSummary {
name,
original_name,
})
.collect(),
},
Err(error) => McpServerOutcome::Failed {
error: error.to_string(),
},
};
outcomes.push((server_name, outcome));
}
Ok(McpStartup {
manager: Arc::new(manager),
outcomes,
})
}
/// Start an MCP server inside the sandbox and return `(url, headers)` for
/// the HTTP connection.
///
/// The outer `Result` is cancellation (the running MCP process group is
/// terminated before returning). The inner `Result` is a non-fatal startup
/// failure the caller reports as `agent.mcp.failed`.
async fn start_sandbox_mcp_server(
sandbox: &RunSandbox,
command: &[String],
port: u16,
env: &HashMap<String, String>,
cancel_token: &CancellationToken,
) -> Result<Result<(String, HashMap<String, String>), String>, Error> {
let launch_script = sandbox_mcp_launch_script(command);
let env_ref = if env.is_empty() { None } else { Some(env) };
if cancel_token.is_cancelled() {
return Err(Error::Cancelled);
}
let launch_result = match sandbox
.exec_command(
&launch_script,
30_000,
None,
env_ref,
Some(cancel_token.child_token()),
)
.await
{
Ok(result) => result,
Err(error) => {
if cancel_token.is_cancelled() {
return Err(Error::Cancelled);
}
return Ok(Err(format!(
"Failed to launch MCP server: {}",
error.display_with_causes()
)));
}
};
let pid = launch_result.stdout.trim().to_string();
info!(pid = %pid, port, "MCP server process launched in sandbox");
// Wait for the server to start listening on the port.
let poll_cmd = format!(
"for i in $(seq 1 30); do ss -tln | grep -q ':{port} ' && echo ready && exit 0; sleep 1; done; echo timeout"
);
let poll_result = sandbox
.exec_command(
&poll_cmd,
60_000,
None,
None,
Some(cancel_token.child_token()),
)
.await;
if cancel_token.is_cancelled() {
kill_mcp_pid(sandbox, &pid).await;
return Err(Error::Cancelled);
}
let poll_result = match poll_result {
Ok(result) => result,
Err(error) => {
return Ok(Err(format!(
"Failed to poll MCP server readiness: {}",
error.display_with_causes()
)));
}
};
if poll_result.stdout.trim() != "ready" {
let stderr = sandbox
.exec_command(
"cat /tmp/mcp_server_stderr.log 2>/dev/null | tail -20",
10_000,
None,
None,
Some(cancel_token.child_token()),
)
.await
.map(|result| result.stdout)
.unwrap_or_default();
return Ok(Err(format!(
"MCP server did not start listening on port {port} within 30s. stderr:\n{stderr}"
)));
}
// The preview URL for the port, or localhost for local sandboxes.
let preview = match sandbox.get_preview_url(port).await {
Ok(preview) => preview,
Err(error) => return Ok(Err(error.display_with_causes())),
};
if cancel_token.is_cancelled() {
kill_mcp_pid(sandbox, &pid).await;
return Err(Error::Cancelled);
}
if let Some(url_and_headers) = preview {
Ok(Ok(url_and_headers))
} else {
info!(port, "No preview URL available, using localhost");
Ok(Ok((format!("http://localhost:{port}"), HashMap::new())))
}
}
fn sandbox_mcp_launch_script(command: &[String]) -> String {
let command_source = match command {
// Sandbox MCP `script` entries resolve to this exact argv shape. The
// surrounding launcher is already the provider-selected Bash, so
// evaluate the source in that process instead of PATH-resolving a
// second interpreter. Grouping keeps the log redirections scoped to
// the whole script, including multi-command and trailing-comment
// forms.
[interpreter, flag, source] if interpreter == "bash" && flag == "-c" => {
format!("{{\n{source}\n}}")
}
_ => shell_join(command),
};
let inner =
format!("{command_source} > /tmp/mcp_server_stdout.log 2>/tmp/mcp_server_stderr.log");
format!(
"setsid \"$BASH\" -c {quoted} </dev/null >/dev/null 2>&1 &\necho $!",
quoted = shell_quote(&inner)
)
}
/// Best-effort kill of a sandbox MCP server process group, used when startup
/// is cancelled after the detached process has been spawned.
async fn kill_mcp_pid(sandbox: &RunSandbox, pid: &str) {
let pid = pid.trim();
if pid.is_empty() {
return;
}
let script =
format!("kill -TERM -{pid} 2>/dev/null; sleep 1; kill -KILL -{pid} 2>/dev/null; true");
if let Err(error) = sandbox.exec_command(&script, 5_000, None, None, None).await {
warn!(pid, error = %error.display_with_causes(), "Failed to kill MCP server process group during cancellation");
}
}
#[cfg(test)]
mod tests {
use super::sandbox_mcp_launch_script;
#[test]
fn launch_script_evaluates_bash_c_source_in_place() {
let script = sandbox_mcp_launch_script(&[
"bash".to_string(),
"-c".to_string(),
"echo hi # trailing comment".to_string(),
]);
assert!(script.starts_with("setsid \"$BASH\" -c "));
assert!(script.contains("echo hi # trailing comment\n}"));
assert!(script.ends_with("&\necho $!"));
}
#[test]
fn launch_script_quotes_other_commands() {
let script = sandbox_mcp_launch_script(&[
"python3".to_string(),
"server.py".to_string(),
"--name".to_string(),
"it's".to_string(),
]);
assert!(script.contains("python3 server.py --name"));
assert!(script.contains("/tmp/mcp_server_stderr.log"));
}
}

263
lib/components/fabro-workflow/tests/it/daytona_integration.rs
View file

@ -30,7 +30,6 @@ use fabro_sandbox::{
use fabro_static::EnvVars;
use fabro_store::{ArtifactKey, ArtifactStore};
use fabro_types::{RunId, StageId, WorkflowSettings, parse_blob_ref};
use fabro_util::shell;
use fabro_workflow::artifact;
use fabro_workflow::context::Context;
use fabro_workflow::error::Error;
@ -1841,9 +1840,12 @@ async fn daytona_playwright_mcp_sandbox_transport() {
);
assert_eq!(install.exit_code, Some(0), "Playwright install failed");
// 2. Start the Playwright MCP server via the sandbox transport resolution path
// 2. The Playwright MCP server as an agent stage gets it: launched in the
// sandbox by pebble and reached over SSE through Daytona's preview link,
// token header included. A scripted model drives the tools, so the test is
// about the sandbox transport and nothing else.
let mcp_port = 3100u16;
let mcp_config = fabro_mcp::config::McpServerSettings {
let server = fabro_mcp::pebble::pebble_server(&fabro_mcp::config::McpServerSettings {
name: "playwright".into(),
transport: fabro_mcp::config::McpTransport::Sandbox {
protocol: fabro_mcp::config::McpHttpProtocol::Sse,
@ -1861,171 +1863,106 @@ async fn daytona_playwright_mcp_sandbox_transport() {
},
current_dir: None,
clear_env: false,
startup_timeout_secs: 30,
startup_timeout_secs: 60,
tool_timeout_secs: 120,
};
});
let (client, _provider) = pebble_coding_agent::test_support::client_from(
pebble_coding_agent::test_support::ScriptedProvider::new(vec![
pebble_coding_agent::test_support::ScriptedCall::response(
pebble_coding_agent::test_support::tool_call_response(
"mcp__playwright__browser_install",
"install",
serde_json::json!({}),
),
),
pebble_coding_agent::test_support::ScriptedCall::response(
pebble_coding_agent::test_support::tool_call_response(
"mcp__playwright__browser_navigate",
"navigate",
serde_json::json!({"url": "https://example.com"}),
),
),
pebble_coding_agent::test_support::ScriptedCall::response(
pebble_coding_agent::test_support::tool_call_response(
"mcp__playwright__browser_snapshot",
"snapshot",
serde_json::json!({}),
),
),
pebble_coding_agent::test_support::ScriptedCall::response(
pebble_coding_agent::test_support::text_response("browsed"),
),
]),
);
let sandbox = Arc::new(sandbox);
let routes = sandbox
.port_routes()
.expect("Daytona forwards ports through preview URLs");
let mut agent = pebble_coding_agent::CodingAgent::builder(
client,
Arc::clone(&sandbox) as Arc<dyn pebble_coding_agent::environment::Environment>,
)
.model("test/model")
.permission_level(pebble_coding_agent::events::PermissionLevel::Full)
.mcp_servers([server])
.port_routes(routes)
.build()
.await
.expect("the agent builds with the sandbox-hosted server");
// Resolve the sandbox transport: start the server, get preview URL, rewrite to
// HTTP
let resolved = match &mcp_config.transport {
fabro_mcp::config::McpTransport::Sandbox {
protocol,
command,
port,
// 3. The server started and its tools are registered.
let statuses = agent.snapshot().mcp_servers().to_vec();
assert_eq!(statuses.len(), 1, "{statuses:?}");
assert_eq!(
statuses[0].error, None,
"the Playwright server should start: {statuses:?}"
);
eprintln!("Discovered {} MCP tools:", statuses[0].tools.len());
for tool in &statuses[0].tools {
eprintln!(" - {}", tool.name);
}
assert!(
statuses[0]
.tools
.iter()
.any(|tool| tool.name == "mcp__playwright__browser_navigate"),
"Should have discovered Playwright tools"
);
// 4. Install the browser, navigate, and snapshot through the agent.
let mut events = agent.subscribe();
let report = agent.prompt("browse example.com").await;
assert!(report.result.is_ok(), "{report:?}");
let mut completions = Vec::new();
while let Ok(event) = events.try_recv() {
if let pebble_coding_agent::events::CodingEvent::ToolCallCompleted {
tool_name,
output,
is_error,
..
} => {
let (url, headers) = {
let cmd_str = shell::shell_join(command);
let inner =
format!("{cmd_str} > /tmp/mcp_server_stdout.log 2>/tmp/mcp_server_stderr.log");
let launch_script = format!(
"setsid \"$BASH\" -c {} </dev/null >/dev/null 2>&1 &\necho $!",
shell::shell_quote(&inner)
);
let launch_result = sandbox
.exec_command(&launch_script, 30_000, None, None, None)
.await
.unwrap();
eprintln!("MCP server PID: {}", launch_result.stdout.trim());
// Wait for server to listen
let poll_cmd = format!(
"for i in $(seq 1 30); do ss -tln | grep -q ':{port} ' && echo ready && exit 0; sleep 1; done; echo timeout"
);
let poll_result = sandbox
.exec_command(&poll_cmd, 60_000, None, None, None)
.await
.unwrap();
eprintln!("Server readiness: {}", poll_result.stdout.trim());
if poll_result.stdout.trim() != "ready" {
let stderr = sandbox
.exec_command(
"cat /tmp/mcp_server_stderr.log 2>/dev/null | tail -20",
10_000,
None,
None,
None,
)
.await
.map(|r| r.stdout)
.unwrap_or_default();
panic!("MCP server did not start on port {port}. stderr:\n{stderr}");
}
sandbox
.get_preview_url(*port)
.await
.unwrap()
.expect("sandbox should support preview URLs")
};
eprintln!("Preview URL: {url}");
let url = fabro_mcp::http_transport::sandbox_mcp_http_url(*protocol, &url).unwrap();
fabro_mcp::config::McpServerSettings {
name: mcp_config.name.clone(),
transport: fabro_mcp::config::McpTransport::Http {
protocol: *protocol,
url,
headers,
},
current_dir: mcp_config.current_dir.clone(),
clear_env: mcp_config.clear_env,
startup_timeout_secs: mcp_config.startup_timeout_secs,
tool_timeout_secs: mcp_config.tool_timeout_secs,
}
}
_ => unreachable!(),
};
// 3. Connect the MCP client to the resolved HTTP endpoint
let mut manager = fabro_mcp::connection_manager::McpConnectionManager::new();
let results = manager.start_servers(&[resolved]).await;
for (name, result) in &results {
match result {
Ok(count) => eprintln!("MCP server '{name}' ready with {count} tools"),
Err(e) => panic!("MCP server '{name}' failed: {e}"),
} = event.event
{
completions.push((tool_name, output, is_error));
}
}
// 4. List the tools to verify we got Playwright tools
let tools = manager.all_tools();
eprintln!("Discovered {} MCP tools:", tools.len());
for (name, info) in tools {
eprintln!(
" - {name}: {}",
info.description.chars().take(80).collect::<String>()
);
}
assert!(!tools.is_empty(), "Should have discovered Playwright tools");
// 5. Install the browser via MCP tool (ensures correct version is available)
let install_tool = tools
.keys()
.find(|k| k.ends_with("browser_install"))
.expect("no browser_install tool found");
eprintln!("Calling tool: {install_tool}");
let install_result = manager.call_tool(install_tool, serde_json::json!({})).await;
match &install_result {
Ok(result) => eprintln!(
"Install result: {}",
result
.content
.first()
.map(|c| format!("{c:?}"))
.unwrap_or_default()
),
Err(e) => eprintln!("Install error (non-fatal): {e}"),
}
// 6. Call the browser_navigate tool to load a page
let nav_tool = tools
.keys()
.find(|k| k.ends_with("browser_navigate"))
.expect("no browser_navigate tool found");
eprintln!("Calling tool: {nav_tool}");
let nav_result = manager
.call_tool(nav_tool, serde_json::json!({"url": "https://example.com"}))
.await;
match &nav_result {
Ok(result) => eprintln!(
"Navigate result: {}",
&result
.content
.first()
.map(|c| format!("{c:?}"))
.unwrap_or_default()
),
Err(e) => eprintln!("Navigate error: {e}"),
}
assert!(nav_result.is_ok(), "Navigate should succeed");
// 7. Take a snapshot to verify the page loaded
let snap_tool = tools
.keys()
.find(|k| k.contains("snapshot"))
.expect("no snapshot tool found");
eprintln!("Calling tool: {snap_tool}");
let snap_result = manager.call_tool(snap_tool, serde_json::json!({})).await;
match &snap_result {
Ok(result) => {
let text = result
.content
.first()
.map(|c| format!("{c:?}"))
.unwrap_or_default();
eprintln!(
"Snapshot result (first 500 chars): {}",
&text[..text.len().min(500)]
);
assert!(
text.contains("Example Domain"),
"Snapshot should contain 'Example Domain'"
);
}
Err(e) => panic!("Snapshot failed: {e}"),
}
let navigate = completions
.iter()
.find(|(name, _, _)| name == "mcp__playwright__browser_navigate")
.expect("navigate ran");
assert!(!navigate.2, "Navigate should succeed: {navigate:?}");
let snapshot = completions
.iter()
.find(|(name, _, _)| name == "mcp__playwright__browser_snapshot")
.expect("snapshot ran");
assert!(!snapshot.2, "Snapshot should succeed: {snapshot:?}");
assert!(
snapshot.1.to_string().contains("Example Domain"),
"Snapshot should contain 'Example Domain'"
);
agent
.shutdown(pebble_coding_agent::ShutdownReason::Completed)
.await
.expect("the agent shuts down");
// 8. Cleanup
sandbox.cleanup().await.unwrap();

4
lib/foundation/fabro-types/src/run_event/agent.rs
View file

@ -77,6 +77,8 @@ pub fn coding_event_name(event: &CodingEvent) -> &'static str {
CodingEvent::LoopDetected => "agent.loop.detected",
CodingEvent::ToolRoundsExhausted { .. } => "agent.tool.rounds.exhausted",
CodingEvent::RouteFailover { .. } => "agent.route.failover",
CodingEvent::McpServerReady { .. } => "agent.mcp.server.ready",
CodingEvent::McpServerFailed { .. } => "agent.mcp.server.failed",
CodingEvent::SteeringInjected { .. } => "agent.steering.injected",
CodingEvent::RoundInterrupted { .. } => "agent.round.interrupted",
CodingEvent::CompactionStarted { .. } => "agent.compaction.started",
@ -122,6 +124,8 @@ pub const CODING_EVENT_NAMES: &[&str] = &[
"agent.loop.detected",
"agent.tool.rounds.exhausted",
"agent.route.failover",
"agent.mcp.server.ready",
"agent.mcp.server.failed",
"agent.steering.injected",
"agent.round.interrupted",
"agent.compaction.started",