Files
donutbrowser/src-tauri/src/remote_session.rs
T

1823 lines
68 KiB
Rust

//! Launching a profile on a remote VM.
//!
//! The desktop app never talks to the Wayfern manager directly. It asks
//! donutbrowser-infra, which holds the service-account credentials and is the
//! only party that can mint a donut-sync token scoped to this user's namespace.
//! That indirection is the point: a desktop client that could call the manager
//! itself would need credentials capable of launching sessions for anyone.
use crate::cloud_errors::{self, FailureCodes};
use crate::profile::types::BrowserProfile;
use crate::remote_exit::ExitReachability;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Mutex;
use std::time::Duration;
use tauri::AppHandle;
/// Which code a remote-session failure resolves to when the backend sends no
/// envelope of its own.
const SESSION_CODES: FailureCodes = FailureCodes {
bad_request: "REMOTE_SESSION_REFUSED",
forbidden: "REMOTE_NOT_ENTITLED",
not_found: "REMOTE_SESSION_NOT_FOUND",
conflict: "REMOTE_SESSION_CONFLICT",
};
/// Why a remote launch failed, mapped to the status the local API should return.
#[derive(Debug)]
pub enum RemoteSessionError {
/// No host of the profile's OS has a free slot right now.
NoCapacity(String),
/// The profile is already open somewhere — locally or in another session.
Conflict(String),
/// The user's plan does not cover remote automation.
NotAuthorised(String),
Other(String),
}
impl std::fmt::Display for RemoteSessionError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::NoCapacity(m) | Self::Conflict(m) | Self::NotAuthorised(m) | Self::Other(m) => {
write!(f, "{m}")
}
}
}
}
impl RemoteSessionError {
/// The `{"code":…,"params":{…}}` string a Tauri command returns.
///
/// The variants carry the backend's own English, which reaches the user
/// untranslated if it is surfaced as-is. This recovers the machine code the
/// frontend has a locale string for.
pub fn to_error_json(&self) -> String {
// The three typed variants know the status they came from; `Other` kept
// only the body, so it is re-read for an embedded envelope.
let (status, message) = match self {
Self::NoCapacity(m) => (503, m),
Self::Conflict(m) => (409, m),
Self::NotAuthorised(m) => (403, m),
Self::Other(m) => return cloud_errors::classify_message(m, SESSION_CODES).to_error_json(),
};
cloud_errors::classify(status, message, SESSION_CODES).to_error_json()
}
}
/// What the backend returns when a session starts.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RemoteSessionOutcome {
pub session_id: String,
pub platform: String,
pub status: String,
}
#[derive(Debug, Serialize)]
struct StartRemoteRequest {
profile_id: String,
/// The profile's own OS. The backend refuses to schedule it anywhere else.
platform: String,
/// Set when the caller wants a page opened once the browser is up.
#[serde(skip_serializing_if = "Option::is_none")]
url: Option<String>,
/// De-duplicates retries so a flaky network cannot open two browsers against
/// one profile.
idempotency_key: String,
}
/// Map a backend status onto a typed error.
///
/// Kept separate from the request so the mapping is testable: getting 503
/// wrong would turn "come back in a minute" into "something is broken",
/// and getting 409 wrong would hide the fact that the profile is already open.
pub fn classify_backend_status(status: u16, body: &str) -> RemoteSessionError {
let message = if body.is_empty() {
format!("remote session request failed with HTTP {status}")
} else {
body.to_string()
};
match status {
503 => RemoteSessionError::NoCapacity(message),
409 => RemoteSessionError::Conflict(message),
401..=403 => RemoteSessionError::NotAuthorised(message),
_ => RemoteSessionError::Other(message),
}
}
/// Build the idempotency key for one launch attempt.
///
/// Derived from the profile and a caller-supplied attempt id rather than
/// random, so a retry of the SAME user action de-duplicates while a genuinely
/// new launch does not. The attempt id is a plain uniqueness token, not a
/// cryptographic value.
pub fn idempotency_key(profile_id: &str, attempt: &str) -> String {
format!("run-remote:{profile_id}:{attempt}")
}
/// Whether this profile's exit rules out running it on a leased host.
///
/// A session runs on a fleet host that pulls the profile — and its proxy record
/// — out of the user's sync namespace, rewriting no addresses along the way. A
/// proxy stored as `127.0.0.1:8080` therefore arrives meaning THAT host's
/// loopback: the browser either cannot connect and the leased hour is burned on
/// a session that never worked, or it falls through and the user's identity
/// egresses from our datacenter. The Cookie Bot has refused this since
/// `remote_exit` existed; interactive sessions take the same profile onto the
/// same hosts and did not, so the same mistake cost a leased hour here.
///
/// A profile with NO exit at all is deliberately allowed through. The Cookie
/// Bot refuses that separately because a night of unattended browsing from a
/// hosting ASN damages an identity, but an interactive session is a person at a
/// keyboard who chose to open this profile and can see where it comes out —
/// and no rule has ever required an exit here. Refusing it would be a new
/// product restriction wearing this bug's error code.
///
/// Split out from the launch because that is the only testable seam:
/// `exit_reachability` reads this machine's proxy and VPN stores and the launch
/// itself needs a fleet.
fn local_exit_refusal(verdict: &ExitReachability) -> Option<RemoteSessionError> {
match verdict {
// An address anyone can dial, so the leased host can dial it too.
ExitReachability::Remote => None,
// See the second paragraph above: allowed on purpose, not overlooked.
ExitReachability::None => None,
// `LocalOnly`, plus `Unknown` — which `remote_exit` produces when it could
// not read the config and which fails closed by design, because "we could
// not confirm it" guessed as "yes" is the failure this whole check exists
// to stop.
unusable => {
// The prose names the offending host, which belongs in the log where
// support can read it. The toast gets the code so it stays translated.
if let Some(detail) = unusable.refusal_detail() {
log::warn!("Refusing an interactive remote session: {detail}");
}
// `Other` rather than a typed variant: the other three are each pinned to
// a status and a meaning — "the fleet is busy", "already open somewhere",
// "not on your plan" — and this refusal is none of them. The code in the
// body is what every surface renders.
Some(RemoteSessionError::Other(
serde_json::json!({ "code": "REMOTE_REQUIRES_REMOTE_EXIT_NODE" }).to_string(),
))
}
}
}
/// Ask donutbrowser-infra to start a remote session for this profile.
///
/// Goes through `api_call_with_retry` so an expired access token is refreshed
/// and the request retried once, rather than surfacing to the user as a
/// spurious "not signed in".
pub async fn start_remote_session(
_app: AppHandle,
profile: &BrowserProfile,
url: Option<String>,
) -> Result<RemoteSessionOutcome, RemoteSessionError> {
let platform = profile
.resolved_os()
.ok_or_else(|| {
RemoteSessionError::Other("profile has no recorded operating system".to_string())
})?
.to_string();
let profile_id = profile.id.to_string();
// Checked here, before the request: the backend is told which profile to
// start but never sees the proxy record, so it cannot derive this — and by
// the time it could, an hour is already leased and billed. Resolving a proxy
// id to an address is only possible on the machine that stores it.
if let Some(refusal) = local_exit_refusal(&crate::cookie_bot::exit_reachability(profile)) {
return Err(refusal);
}
// One key for this user action: a retry inside api_call_with_retry must
// de-duplicate rather than open a second browser on the same profile.
let key = idempotency_key(&profile_id, &uuid::Uuid::new_v4().to_string());
let endpoint = format!("{}/api/remote-sessions", crate::cloud_auth::CLOUD_API_URL);
let outcome = crate::cloud_auth::CLOUD_AUTH
.api_call_with_retry(|token| {
let endpoint = endpoint.clone();
let body = StartRemoteRequest {
profile_id: profile_id.clone(),
platform: platform.clone(),
url: url.clone(),
idempotency_key: key.clone(),
};
async move {
let response = reqwest::Client::new()
.post(&endpoint)
.bearer_auth(token)
.json(&body)
.send()
.await
.map_err(|e| format!("reach backend: {e}"))?;
let status = response.status().as_u16();
if !(200..300).contains(&status) {
let text = response.text().await.unwrap_or_default();
// Encode the status so api_call_with_retry can spot a 401, and so
// classify_backend_status can recover the kind afterwards.
return Err(format!("({status}) {text}"));
}
response
.json::<RemoteSessionOutcome>()
.await
.map_err(|e| format!("decode response: {e}"))
}
})
.await
.map_err(|e| classify_error_string(&e))?;
// Gate the profile here rather than waiting for the stream to say so. A host
// starts pulling this profile the instant the backend accepts, and the first
// transition can arrive seconds later or, on a machine whose stream is down,
// not at all. Those seconds are enough for a user to press Run.
note_session_started(&profile.id.to_string(), &outcome.session_id);
Ok(outcome)
}
/// What the backend returns when a session is stopped.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct EndRemoteSessionOutcome {
pub session_id: String,
pub status: String,
/// What the session actually cost, in seconds.
pub billed_seconds: u64,
}
/// Gate a profile the moment a launch is accepted, and pull when one is stopped.
///
/// The event stream is the normal way this machine learns a session's state, but
/// it is not the only way a session starts or ends and it is not guaranteed to
/// be connected. Both of these are called directly by the launch and stop paths
/// so the gate never depends on a socket being up: a launch whose first
/// transition is missed would leave the profile openable locally while a host
/// wrote to it, and a stop whose `closed` frame is missed would leave the
/// session's work sitting in cloud storage with nothing to pull it.
pub fn note_session_started(profile_id: &str, session_id: &str) {
crate::remote_handoff::note_running(profile_id, session_id);
}
pub fn note_session_stopped(app: &AppHandle, session_id: &str) {
let Some(profile_id) = crate::remote_handoff::profile_for_session(session_id) else {
// A session this machine never saw start. There is nothing recorded to
// pull for, and inventing a profile id would gate the wrong profile.
return;
};
if crate::remote_handoff::note_ended(&profile_id, session_id) {
crate::remote_handoff::schedule_pull(app.clone(), profile_id);
}
}
/// Ask donutbrowser-infra to stop a remote session.
///
/// Without this the only thing that ends a session is the fleet's own two-hour
/// cap, so every launch bills the full 7200s however briefly it was used — a
/// handful of runs exhausts an allowance meant for a hundred. The backend
/// refuses to retire a row it could not stop on the fleet, so a successful
/// return here means the browser is really down and the profile lock released.
pub async fn end_remote_session(
session_id: &str,
) -> Result<EndRemoteSessionOutcome, RemoteSessionError> {
let endpoint = format!(
"{}/api/remote-sessions/{}",
crate::cloud_auth::CLOUD_API_URL,
urlencoding::encode(session_id)
);
crate::cloud_auth::CLOUD_AUTH
.api_call_with_retry(|token| {
let endpoint = endpoint.clone();
async move {
let response = reqwest::Client::new()
.delete(&endpoint)
.bearer_auth(token)
.send()
.await
.map_err(|e| format!("reach backend: {e}"))?;
let status = response.status().as_u16();
if !(200..300).contains(&status) {
let text = response.text().await.unwrap_or_default();
return Err(format!("({status}) {text}"));
}
response
.json::<EndRemoteSessionOutcome>()
.await
.map_err(|e| format!("decode response: {e}"))
}
})
.await
.map_err(|e| classify_error_string(&e))
}
/// Recover a typed error from `api_call_with_retry`'s string.
///
/// That helper flattens everything to `String` to do its 401 sniffing, so the
/// status is re-parsed here rather than lost — a 503 surfacing as a generic
/// failure would tell the user their fleet is broken when it is merely busy.
pub fn classify_error_string(message: &str) -> RemoteSessionError {
match cloud_errors::split_status(message) {
Some((status, body)) => classify_backend_status(status, body),
None => RemoteSessionError::Other(message.to_string()),
}
}
/// A session as the backend currently sees it.
///
/// `POST /api/remote-sessions` hands back the literal string `provisioning`
/// and nothing else, so until this type existed the only way anyone observed a
/// session becoming usable was by reading the production database.
#[derive(Debug, Clone, Serialize, Deserialize, utoipa::ToSchema)]
pub struct RemoteSessionState {
pub session_id: String,
#[serde(default)]
pub profile_id: Option<String>,
#[serde(default)]
pub platform: Option<String>,
/// `provisioning` | `ready` | `live` | `closed` | `error`.
///
/// Named `state` because that is what `RemoteSessionView` in
/// donutbrowser-infra actually sends. It carried the name `status` until a
/// real payload was compared against it, and because the field had no
/// default, every list and single read failed at `missing field \`status\``
/// and surfaced as CLOUD_UNREACHABLE. The alias keeps the launch reply —
/// which predates the reconciled vocabulary and still says `status` —
/// decoding through the same type.
#[serde(rename = "state", alias = "status")]
pub state: String,
/// The relay is up, so the session can actually be driven.
#[serde(default)]
pub cdp_ready: bool,
/// `interactive` or `cookie_bot`.
#[serde(default)]
pub kind: Option<String>,
/// Set when this session belongs to a cookie-bot run.
#[serde(default)]
pub run_id: Option<String>,
/// The team the hours are attributed to, when the caller belongs to one.
#[serde(default)]
pub team_id: Option<String>,
#[serde(default)]
pub started_at: Option<String>,
/// When it finished. The backend sends one timestamp, not a
/// `ready_at`/`closed_at` pair.
#[serde(default)]
pub ended_at: Option<String>,
/// Why it ended: `stopped_by_user`, `max_duration`, `lost the profile lock`…
#[serde(default)]
pub close_reason: Option<String>,
/// What it has cost so far. A live session is already being charged, so this
/// is the running wall clock rather than 0 until it closes.
#[serde(default)]
pub billed_seconds: Option<u64>,
}
#[derive(Debug, Clone, Deserialize)]
struct RemoteSessionListResponse {
#[serde(default)]
sessions: Vec<RemoteSessionState>,
}
/// Every session the caller currently owns.
pub async fn list_remote_sessions() -> Result<Vec<RemoteSessionState>, RemoteSessionError> {
let endpoint = format!("{}/api/remote-sessions", crate::cloud_auth::CLOUD_API_URL);
let response: RemoteSessionListResponse = get_json(endpoint).await?;
Ok(response.sessions)
}
/// One session's real state, for a one-shot read.
///
/// The event stream is how the desktop normally learns a transition; this is
/// for the cases a stream cannot serve — a window opened after the fact, or a
/// reconnect that needs to confirm what it missed.
pub async fn get_remote_session(
session_id: &str,
) -> Result<RemoteSessionState, RemoteSessionError> {
let endpoint = format!(
"{}/api/remote-sessions/{}",
crate::cloud_auth::CLOUD_API_URL,
urlencoding::encode(session_id)
);
get_json(endpoint).await
}
async fn get_json<T: serde::de::DeserializeOwned>(
endpoint: String,
) -> Result<T, RemoteSessionError> {
crate::cloud_auth::CLOUD_AUTH
.api_call_with_retry(|token| {
let endpoint = endpoint.clone();
async move {
let response = reqwest::Client::new()
.get(&endpoint)
.bearer_auth(token)
.send()
.await
.map_err(|e| format!("reach backend: {e}"))?;
let status = response.status().as_u16();
if !(200..300).contains(&status) {
let text = response.text().await.unwrap_or_default();
return Err(format!("({status}) {text}"));
}
response
.json::<T>()
.await
.map_err(|e| format!("decode response: {e}"))
}
})
.await
.map_err(|e| classify_error_string(&e))
}
// --- Driving a session ------------------------------------------------------
/// Where to attach a CDP client for one session.
///
/// The descriptor is deliberately OPAQUE and server-decided. The desktop knows
/// nothing about the fleet — not its hostname, not its paths, not a credential
/// it would accept — and switches only on `auth`. That is what lets the server
/// move the endpoint, or hand out a different kind of credential, without a
/// desktop release; a hard-coded URL in a shipped binary could not be moved at
/// all.
#[derive(Debug, Clone, Deserialize)]
pub struct CdpEndpoint {
#[serde(default)]
pub session_id: String,
pub ws_url: String,
/// Wire protocol the endpoint speaks.
#[serde(default)]
pub protocol: String,
/// How to authenticate: `bearer` means the same access token used for REST.
#[serde(default)]
pub auth: String,
}
/// The only credential scheme this build can present.
const AUTH_BEARER: &str = "bearer";
/// The only relay protocol this build speaks.
const PROTOCOL_CDP_RELAY_1: &str = "cdp-relay/1";
/// Endpoints already resolved, keyed by session id.
///
/// A session's endpoint does not move while it lives, and every tool call would
/// otherwise pay a cloud round trip before it could send its first byte.
static CDP_ENDPOINTS: Mutex<Option<HashMap<String, CdpEndpoint>>> = Mutex::new(None);
/// Ask the backend where to attach for `session_id`.
pub async fn cdp_endpoint(session_id: &str) -> Result<CdpEndpoint, RemoteSessionError> {
if let Some(cached) = with_endpoints(|map| map.get(session_id).cloned()) {
return Ok(cached);
}
let endpoint = format!(
"{}/api/remote-sessions/{}/cdp",
crate::cloud_auth::CLOUD_API_URL,
urlencoding::encode(session_id)
);
let mut resolved: CdpEndpoint = get_json(endpoint).await?;
if resolved.session_id.is_empty() {
resolved.session_id = session_id.to_string();
}
if let Some(reason) = unsupported_descriptor(&resolved) {
return Err(RemoteSessionError::Other(reason));
}
with_endpoints(|map| map.insert(session_id.to_string(), resolved.clone()));
Ok(resolved)
}
/// Why this build cannot use a descriptor, if it cannot.
///
/// A scheme or protocol this version does not implement has to fail loudly.
/// Guessing at a credential scheme would send the user's access token somewhere
/// it was never meant to go, and ignoring the fields would present the wrong
/// credential on a wire expecting another — both of which read as "remote
/// driving is broken" rather than "this app is out of date".
///
/// An empty field means the server stated nothing, which is how a descriptor
/// that predates the field looks; the historic behaviour is then the answer.
fn unsupported_descriptor(endpoint: &CdpEndpoint) -> Option<String> {
if !endpoint.auth.is_empty() && endpoint.auth != AUTH_BEARER {
return Some(format!(
"this version cannot attach to a remote browser using {:?} authentication; update Donut Browser",
endpoint.auth
));
}
if !endpoint.protocol.is_empty() && endpoint.protocol != PROTOCOL_CDP_RELAY_1 {
return Some(format!(
"this version does not speak {:?}; update Donut Browser",
endpoint.protocol
));
}
None
}
fn with_endpoints<T>(f: impl FnOnce(&mut HashMap<String, CdpEndpoint>) -> T) -> T {
let mut guard = CDP_ENDPOINTS
.lock()
.unwrap_or_else(std::sync::PoisonError::into_inner);
f(guard.get_or_insert_with(HashMap::new))
}
fn forget_endpoint(session_id: &str) {
with_endpoints(|map| map.remove(session_id));
}
/// The access token a relay attach presents.
///
/// One place, so the credential a WebSocket carries is provably the same one
/// every REST call already carries, and no second copy of the load-and-check
/// logic can drift from it.
pub fn access_token_for_cdp() -> Result<String, String> {
crate::cloud_auth::CloudAuthManager::load_access_token()?
.filter(|token| !token.is_empty())
.ok_or_else(|| "not signed in to Donut cloud".to_string())
}
/// Sessions that can be driven right now, keyed by the profile they hold.
///
/// Maintained from the event stream so deciding "is this profile running on the
/// fleet?" costs a lock rather than a cloud round trip on every tool call.
static LIVE_BY_PROFILE: Mutex<Option<HashMap<String, RemoteSessionState>>> = Mutex::new(None);
/// Whether the stream has delivered a snapshot and has not dropped since.
///
/// Without this the index cannot distinguish "no session for that profile" from
/// "nothing has told us about any session yet", and the second answered as the
/// first is exactly how a live remote profile reports itself as not running.
static INDEX_AUTHORITATIVE: AtomicBool = AtomicBool::new(false);
fn with_index<T>(f: impl FnOnce(&mut HashMap<String, RemoteSessionState>) -> T) -> T {
let mut guard = LIVE_BY_PROFILE
.lock()
.unwrap_or_else(std::sync::PoisonError::into_inner);
f(guard.get_or_insert_with(HashMap::new))
}
/// A session that is up AND attachable.
///
/// `provisioning` and `ready` are both "the browser is not there yet"; treating
/// either as drivable is what makes a client attach into a connection that
/// never establishes.
pub fn is_drivable(session: &RemoteSessionState) -> bool {
session.state == "live" && session.cdp_ready
}
/// A session that will never write to the profile again.
///
/// Deliberately NOT the negation of [`is_drivable`]. A `provisioning` session
/// has already taken the profile lock and its host is about to pull the profile
/// down and launch a browser on it, so it owns the profile every bit as much as
/// a `live` one does — it is simply not attachable yet. Treating "not drivable"
/// as "finished" would lift the local launch gate during the one minute a host
/// spends starting up, which is the window in which two writers do the most
/// damage.
pub fn is_terminal(session: &RemoteSessionState) -> bool {
matches!(session.state.as_str(), "closed" | "error")
}
/// Apply one session to the index, and to the local launch gate.
///
/// A session that stopped being drivable is removed, but only by the session
/// that owns the slot: a late `closed` for a finished session must not evict
/// the live one that replaced it.
fn index_session(app: Option<&AppHandle>, session: &RemoteSessionState) {
let Some(profile_id) = session.profile_id.clone() else {
return;
};
// The gate is maintained from the same frames as the index, because these are
// the only frames that exist. It is deliberately keyed off `is_terminal`
// rather than `is_drivable`: a provisioning host already owns the profile.
if is_terminal(session) {
if crate::remote_handoff::note_ended(&profile_id, &session.session_id) {
if let Some(app) = app {
crate::remote_handoff::schedule_pull(app.clone(), profile_id.clone());
}
}
} else {
crate::remote_handoff::note_running(&profile_id, &session.session_id);
}
if is_drivable(session) {
with_index(|map| map.insert(profile_id, session.clone()));
return;
}
forget_endpoint(&session.session_id);
with_index(|map| {
let owns_slot = map
.get(&profile_id)
.is_some_and(|held| held.session_id == session.session_id);
if owns_slot {
map.remove(&profile_id);
}
});
}
/// Replace the whole index from a full listing, and reconcile the launch gate.
fn reindex(app: Option<&AppHandle>, sessions: &[RemoteSessionState]) {
// Every session the backend still considers unfinished. A profile this
// machine last saw running whose session is not in here finished while
// nothing was watching — its work is in cloud storage and has not been pulled.
let unfinished: std::collections::HashSet<String> = sessions
.iter()
.filter(|session| !is_terminal(session))
.map(|session| session.session_id.clone())
.collect();
for session in sessions {
index_session(app, session);
}
for profile_id in crate::remote_handoff::reconcile(&unfinished) {
if let Some(app) = app {
crate::remote_handoff::schedule_pull(app.clone(), profile_id);
}
}
let next: HashMap<String, RemoteSessionState> = sessions
.iter()
.filter(|session| is_drivable(session))
.filter_map(|session| {
session
.profile_id
.clone()
.map(|profile_id| (profile_id, session.clone()))
})
.collect();
let live: std::collections::HashSet<&str> = next
.values()
.map(|session| session.session_id.as_str())
.collect();
with_endpoints(|map| map.retain(|session_id, _| live.contains(session_id.as_str())));
with_index(|map| *map = next);
}
/// The drivable session holding `profile_id`, if there is one.
///
/// Consults the in-process index first. Only when the stream is not delivering
/// transitions does it spend a cloud round trip, because in that state the
/// index cannot be trusted to be complete and answering "not running" from it
/// would hide a session the user is already paying for.
pub async fn live_session_for_profile(profile_id: &str) -> Option<RemoteSessionState> {
if let Some(session) = with_index(|map| map.get(profile_id).cloned()) {
return Some(session);
}
if INDEX_AUTHORITATIVE.load(Ordering::SeqCst) {
return None;
}
match list_remote_sessions().await {
Ok(sessions) => {
reindex(None, &sessions);
with_index(|map| map.get(profile_id).cloned())
}
Err(e) => {
log::debug!("Could not refresh remote sessions while resolving a CDP target: {e}");
None
}
}
}
// --- Live state, without polling -------------------------------------------
/// A session transition. Payload is the session as the backend sees it.
pub const EVENT_SESSION_STATE: &str = "remote-session-state";
/// Everything the caller owns, sent once when the stream connects.
pub const EVENT_SESSION_SNAPSHOT: &str = "remote-session-snapshot";
/// Whether the desktop is currently receiving transitions.
pub const EVENT_STREAM_STATUS: &str = "remote-session-stream";
/// How long a silent stream is trusted before it is treated as dead.
///
/// The backend heartbeats, so silence past this means the socket died without
/// an error — which is exactly what a laptop returning from sleep sees. Held
/// well above the heartbeat interval so a slow network cannot cause a churn of
/// reconnects.
const STREAM_IDLE_TIMEOUT: Duration = Duration::from_secs(90);
/// First reconnect delay. Doubles per failure.
const RECONNECT_BASE: Duration = Duration::from_secs(1);
/// Ceiling on the reconnect delay.
const RECONNECT_MAX: Duration = Duration::from_secs(60);
/// Where the backoff restarts after an auth failure. Being signed out or
/// unentitled is not something a fast retry fixes, and hammering an endpoint
/// that will keep saying no is how a background task becomes a battery bug.
const AUTH_BACKOFF_ATTEMPT: u32 = 6;
/// Granularity of the cancellable sleep, so a shutdown is not held up by a
/// minute-long backoff.
const SHUTDOWN_POLL: Duration = Duration::from_millis(250);
static STREAM_RUNNING: AtomicBool = AtomicBool::new(false);
static STREAM_TASK: Mutex<Option<tauri::async_runtime::JoinHandle<()>>> = Mutex::new(None);
/// One frame off the wire.
#[derive(Debug, Clone, PartialEq, Eq, Default)]
pub struct SseFrame {
pub id: Option<String>,
pub event: Option<String>,
pub data: String,
}
/// Incremental `text/event-stream` decoder.
///
/// Kept as a value with no IO so the framing rules — multi-line data, the
/// blank-line terminator, comments, CRLF, a chunk boundary landing mid-field —
/// are testable without a server.
#[derive(Debug, Default)]
pub struct SseDecoder {
buffer: Vec<u8>,
event: Option<String>,
data: String,
id: Option<String>,
}
impl SseDecoder {
pub fn new() -> Self {
Self::default()
}
/// Feed bytes, get back whatever frames completed.
pub fn push(&mut self, chunk: &[u8]) -> Vec<SseFrame> {
self.buffer.extend_from_slice(chunk);
let mut frames = Vec::new();
// A newline is never part of a multi-byte UTF-8 sequence, so splitting the
// raw bytes on it cannot cut a character in half.
while let Some(index) = self.buffer.iter().position(|b| *b == b'\n') {
let line: Vec<u8> = self.buffer.drain(..=index).collect();
let line = String::from_utf8_lossy(&line[..line.len() - 1]);
let line = line.strip_suffix('\r').unwrap_or(&line);
if line.is_empty() {
if let Some(frame) = self.take_frame() {
frames.push(frame);
}
continue;
}
// A leading colon is a comment; some proxies keep a stream alive with
// nothing else, so it must not be mistaken for a field.
if line.starts_with(':') {
continue;
}
let (field, value) = match line.split_once(':') {
Some((field, value)) => (field, value.strip_prefix(' ').unwrap_or(value)),
None => (line, ""),
};
match field {
"event" => self.event = Some(value.to_string()),
"id" => self.id = Some(value.to_string()),
"data" => {
if !self.data.is_empty() {
self.data.push('\n');
}
self.data.push_str(value);
}
// `retry` is the server's reconnect hint; this client's own backoff
// already bounds that, so honouring it would only make the interval
// less predictable.
_ => {}
}
}
frames
}
fn take_frame(&mut self) -> Option<SseFrame> {
let event = self.event.take();
let id = self.id.take();
let data = std::mem::take(&mut self.data);
if data.is_empty() && event.is_none() {
return None;
}
Some(SseFrame { id, event, data })
}
}
/// A frame that carries nothing the frontend needs.
fn is_heartbeat(kind: &str) -> bool {
matches!(kind, "heartbeat" | "ping" | "keepalive")
}
/// Turn one decoded frame into the Tauri event and payload it becomes.
///
/// The discriminator lives INSIDE the JSON, not in the SSE `event:` line: Nest
/// only sets `MessageEvent.type` for the heartbeat, so every real frame arrives
/// as the default `message` event carrying
/// `{"type":"snapshot"|"state"|"progress"|"closed","at":…,"sessions"|"session":…}`.
/// Routing on the event name alone emitted that whole envelope as a session, so
/// `profile_id` was always undefined and the frontend dropped every transition
/// — the desktop stayed exactly as blind between launch and stop as it was
/// before the stream existed.
///
/// The SSE name is still honoured when there is one, so a backend that starts
/// naming its frames keeps working without a desktop release.
pub fn route_frame(event: Option<&str>, data: &str) -> Option<(&'static str, serde_json::Value)> {
if let Some(name) = event {
if is_heartbeat(name) {
return None;
}
}
let payload = match serde_json::from_str::<serde_json::Value>(data) {
Ok(value) => value,
Err(e) => {
log::warn!("Ignoring malformed remote-session event: {e}");
return None;
}
};
let object = payload.as_object()?;
let kind = object
.get("type")
.and_then(serde_json::Value::as_str)
.or(event)
.unwrap_or("state");
if is_heartbeat(kind) {
return None;
}
if kind == "snapshot" {
let sessions = object
.get("sessions")
.cloned()
.unwrap_or_else(|| serde_json::Value::Array(Vec::new()));
return Some((
EVENT_SESSION_SNAPSHOT,
serde_json::json!({ "sessions": sessions }),
));
}
// `state`, `progress` and `closed` all wrap one session. A frame that
// carries neither an inner `session` nor a session of its own is not
// something a consumer can apply, and forwarding it is how the envelope bug
// happened in the first place.
if let Some(session) = object.get("session").filter(|v| v.is_object()) {
return Some((EVENT_SESSION_STATE, session.clone()));
}
if object.contains_key("session_id") {
return Some((EVENT_SESSION_STATE, payload));
}
log::warn!("Ignoring remote-session frame with no session: {kind}");
None
}
/// Delay before reconnect attempt `attempt`, doubling to a ceiling.
pub fn reconnect_delay(attempt: u32) -> Duration {
let factor = 1u64.checked_shl(attempt.min(16)).unwrap_or(u64::MAX);
RECONNECT_BASE
.saturating_mul(factor.min(u32::MAX as u64) as u32)
.min(RECONNECT_MAX)
}
/// Start receiving session transitions. Idempotent: a second call while the
/// stream is up is a no-op rather than a second socket.
pub fn start_session_events(app: AppHandle) {
if STREAM_RUNNING.swap(true, Ordering::SeqCst) {
return;
}
let handle = tauri::async_runtime::spawn(async move {
run_session_events(app).await;
});
if let Ok(mut slot) = STREAM_TASK.lock() {
*slot = Some(handle);
}
}
/// Stop receiving. Safe to call when nothing is running.
pub fn stop_session_events() {
// Cleared unconditionally: unsubscribing is what sign-out does, and an index
// left marked authoritative would keep answering from state nothing is
// maintaining any more.
INDEX_AUTHORITATIVE.store(false, Ordering::SeqCst);
if !STREAM_RUNNING.swap(false, Ordering::SeqCst) {
return;
}
if let Ok(mut slot) = STREAM_TASK.lock() {
if let Some(handle) = slot.take() {
handle.abort();
}
}
}
/// Whether the subscriber task is alive.
pub fn session_events_running() -> bool {
STREAM_RUNNING.load(Ordering::SeqCst)
}
async fn run_session_events(app: AppHandle) {
let mut attempt = 0u32;
// Echoed back on reconnect as `Last-Event-ID`, per the SSE spec, IF the
// backend ever labels its frames. It does not today — `stream()` emits no
// `id:` line and keeps no replay buffer — so this stays `None` and nothing is
// resumed. What bounds the loss instead is the stream opening with a full
// snapshot, which re-states every session the caller still owns.
let mut last_event_id: Option<String> = None;
while STREAM_RUNNING.load(Ordering::SeqCst) {
match connect_session_events(last_event_id.as_deref()).await {
Ok(response) => {
attempt = 0;
emit_stream_status(&app, true, None);
match consume_session_events(&app, response, &mut last_event_id).await {
Ok(()) => {
log::info!("Remote session stream closed by the backend");
emit_stream_status(&app, false, None);
}
Err(reason) => {
log::warn!("Remote session stream ended: {reason}");
emit_stream_status(&app, false, Some(&reason));
}
}
}
Err(err) => {
let reason = err.to_string();
if matches!(err, RemoteSessionError::NotAuthorised(_)) {
attempt = attempt.max(AUTH_BACKOFF_ATTEMPT);
}
log::warn!("Remote session stream could not connect: {reason}");
emit_stream_status(&app, false, Some(&reason));
}
}
if !STREAM_RUNNING.load(Ordering::SeqCst) {
break;
}
let delay = jittered(reconnect_delay(attempt));
attempt = attempt.saturating_add(1);
sleep_unless_stopped(delay).await;
}
log::info!("Remote session stream stopped");
}
/// Spread reconnects so every desktop that lost the same backend does not come
/// back in the same millisecond.
fn jittered(delay: Duration) -> Duration {
use rand::RngExt;
let factor = rand::rng().random_range(0.8f64..1.2f64);
delay.mul_f64(factor)
}
async fn sleep_unless_stopped(total: Duration) {
let mut slept = Duration::ZERO;
while slept < total && STREAM_RUNNING.load(Ordering::SeqCst) {
let step = SHUTDOWN_POLL.min(total - slept);
tokio::time::sleep(step).await;
slept += step;
}
}
/// The stream's own HTTP client.
///
/// Deliberately not the shared one: a total request timeout would kill a
/// healthy stream on schedule, so only the connect phase is bounded and
/// liveness is enforced by the idle timeout instead.
fn stream_client() -> &'static reqwest::Client {
static CLIENT: std::sync::OnceLock<reqwest::Client> = std::sync::OnceLock::new();
CLIENT.get_or_init(|| {
reqwest::Client::builder()
.connect_timeout(Duration::from_secs(10))
.build()
.unwrap_or_else(|_| reqwest::Client::new())
})
}
async fn connect_session_events(
last_event_id: Option<&str>,
) -> Result<reqwest::Response, RemoteSessionError> {
let endpoint = format!(
"{}/api/remote-sessions/events",
crate::cloud_auth::CLOUD_API_URL
);
crate::cloud_auth::CLOUD_AUTH
.api_call_with_retry(|token| {
let endpoint = endpoint.clone();
let resume_from = last_event_id.map(str::to_string);
async move {
// Going through api_call_with_retry means a token that expired during
// a long stream is refreshed on the reconnect instead of turning a
// signed-in desktop into a permanently silent one.
let mut request = stream_client()
.get(&endpoint)
.bearer_auth(token)
.header(reqwest::header::ACCEPT, "text/event-stream")
.header(reqwest::header::CACHE_CONTROL, "no-cache");
if let Some(id) = resume_from {
request = request.header("Last-Event-ID", id);
}
let response = request
.send()
.await
.map_err(|e| format!("reach backend: {e}"))?;
let status = response.status().as_u16();
if !(200..300).contains(&status) {
let text = response.text().await.unwrap_or_default();
return Err(format!("({status}) {text}"));
}
Ok(response)
}
})
.await
.map_err(|e| classify_error_string(&e))
}
async fn consume_session_events(
app: &AppHandle,
response: reqwest::Response,
last_event_id: &mut Option<String>,
) -> Result<(), String> {
use futures_util::StreamExt;
let mut stream = response.bytes_stream();
let mut decoder = SseDecoder::new();
loop {
if !STREAM_RUNNING.load(Ordering::SeqCst) {
return Ok(());
}
let next = tokio::time::timeout(STREAM_IDLE_TIMEOUT, stream.next()).await;
let chunk = match next {
// No heartbeat. The socket is gone even though nothing errored, which
// is what a machine returning from sleep sees.
Err(_) => return Err("no heartbeat within the idle timeout".to_string()),
Ok(None) => return Ok(()),
Ok(Some(Err(e))) => return Err(format!("stream error: {e}")),
Ok(Some(Ok(bytes))) => bytes,
};
for frame in decoder.push(&chunk) {
if let Some(id) = &frame.id {
*last_event_id = Some(id.clone());
}
dispatch_frame(app, &frame);
}
}
}
fn dispatch_frame(app: &AppHandle, frame: &SseFrame) {
let Some((target, payload)) = route_frame(frame.event.as_deref(), &frame.data) else {
return;
};
apply_to_index(Some(app), target, &payload);
use tauri::Emitter;
if let Err(e) = app.emit(target, payload) {
log::warn!("Failed to emit {target}: {e}");
}
}
/// Keep the drivable-session index in step with what the stream just said.
///
/// The same frames that tell the frontend a session went live are the only
/// thing that can tell the CDP resolver so without polling, and a resolver that
/// polls would put a cloud round trip in front of every automation call.
pub fn apply_to_index(app: Option<&AppHandle>, target: &str, payload: &serde_json::Value) {
if target == EVENT_SESSION_SNAPSHOT {
let Some(array) = payload.get("sessions").and_then(|v| v.as_array()) else {
// Marking the index authoritative off a frame that carried no list would
// answer "no session" for every profile until the next reconnect.
log::warn!("Ignoring a remote-session snapshot that carried no session list");
return;
};
let mut sessions = Vec::with_capacity(array.len());
for value in array {
match serde_json::from_value::<RemoteSessionState>(value.clone()) {
Ok(session) => sessions.push(session),
Err(e) => log::warn!("Skipping an undecodable session in the snapshot: {e}"),
}
}
reindex(app, &sessions);
INDEX_AUTHORITATIVE.store(true, Ordering::SeqCst);
return;
}
if target == EVENT_SESSION_STATE {
match serde_json::from_value::<RemoteSessionState>(payload.clone()) {
Ok(session) => index_session(app, &session),
Err(e) => log::warn!("Ignoring an undecodable session transition: {e}"),
}
}
}
fn emit_stream_status(app: &AppHandle, connected: bool, reason: Option<&str>) {
if !connected {
// A dropped stream means transitions are being missed, so the index stops
// being an answer and becomes a cache: a miss now costs one cloud read
// rather than silently reporting a live session as absent.
INDEX_AUTHORITATIVE.store(false, Ordering::SeqCst);
}
use tauri::Emitter;
let payload = serde_json::json!({ "connected": connected, "reason": reason });
if let Err(e) = app.emit(EVENT_STREAM_STATUS, payload) {
log::warn!("Failed to emit {EVENT_STREAM_STATUS}: {e}");
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn no_capacity_is_distinguished_from_a_real_failure() {
// 503 means "come back in a minute", not "something is broken" — conflating
// them would make a busy fleet look like an outage to the user.
assert!(matches!(
classify_backend_status(503, "no macos host free"),
RemoteSessionError::NoCapacity(_)
));
assert!(matches!(
classify_backend_status(500, "boom"),
RemoteSessionError::Other(_)
));
}
#[test]
fn conflict_is_surfaced_so_the_user_learns_the_profile_is_open() {
assert!(matches!(
classify_backend_status(409, "profile already has a live session"),
RemoteSessionError::Conflict(_)
));
}
#[test]
fn payment_and_auth_failures_map_to_not_authorised() {
for status in [401u16, 402, 403] {
assert!(
matches!(
classify_backend_status(status, ""),
RemoteSessionError::NotAuthorised(_)
),
"status {status} should be NotAuthorised"
);
}
}
#[test]
fn an_empty_body_still_produces_a_useful_message() {
let err = classify_backend_status(500, "");
assert!(err.to_string().contains("500"));
}
#[test]
fn a_status_encoded_error_string_round_trips_to_its_kind() {
// api_call_with_retry flattens everything to String to sniff for 401s; the
// status must survive that or a busy fleet looks like a broken one.
assert!(matches!(
classify_error_string("(503) no macos host free"),
RemoteSessionError::NoCapacity(_)
));
assert!(matches!(
classify_error_string("(409) already running"),
RemoteSessionError::Conflict(_)
));
}
#[test]
fn an_unencoded_error_string_is_not_misread_as_a_status() {
assert!(matches!(
classify_error_string("reach backend: connection refused"),
RemoteSessionError::Other(_)
));
}
#[test]
fn the_stop_response_parses_what_the_backend_actually_sends() {
// Pinned against EndRemoteSessionOutcome in donutbrowser-infra
// (apps/backend/src/remote-sessions/remote-sessions.service.ts). A field
// name that does not match makes every stop fail at the decode step, and
// the session then runs to the 2h cap and bills 7200s — the exact defect
// this endpoint exists to fix, reintroduced silently.
let outcome: EndRemoteSessionOutcome =
serde_json::from_str(r#"{"session_id":"sess-1","status":"closed","billed_seconds":42}"#)
.expect("the backend's stop payload must deserialize");
assert_eq!(outcome.session_id, "sess-1");
assert_eq!(outcome.status, "closed");
assert_eq!(outcome.billed_seconds, 42);
}
#[test]
fn a_stop_of_an_unknown_session_is_not_reported_as_capacity() {
// The backend 404s a session that is not the caller's. Mapping that to
// NoCapacity would tell the user the fleet is busy and invite a retry.
assert!(matches!(
classify_error_string("(404) No such remote session"),
RemoteSessionError::Other(_)
));
}
#[test]
fn idempotency_key_is_stable_for_one_attempt_and_distinct_across_attempts() {
let a = idempotency_key("p1", "attempt-1");
assert_eq!(a, idempotency_key("p1", "attempt-1"));
assert_ne!(a, idempotency_key("p1", "attempt-2"));
assert_ne!(a, idempotency_key("p2", "attempt-1"));
}
#[test]
fn a_typed_failure_becomes_a_code_the_frontend_can_translate() {
// The variants carry the backend's English. Surfacing that verbatim is
// how an untranslated string reaches a Russian user.
let busy = RemoteSessionError::NoCapacity("no macos host free".to_string());
assert_eq!(busy.to_error_json(), r#"{"code":"REMOTE_NO_CAPACITY"}"#);
let taken = RemoteSessionError::Conflict("profile already has a live session".to_string());
assert_eq!(
taken.to_error_json(),
r#"{"code":"REMOTE_SESSION_CONFLICT"}"#
);
}
#[test]
fn a_local_only_exit_is_refused_before_a_host_is_leased() {
// The profile and its proxy record are copied onto the fleet unrewritten,
// so this loopback address would mean the FLEET's loopback. Accepting the
// launch bills an hour for a session that cannot reach the user's exit.
let refusal = local_exit_refusal(&ExitReachability::LocalOnly {
host: "127.0.0.1".to_string(),
source: "proxy",
})
.expect("a loopback proxy is unusable from a leased host");
assert_eq!(
refusal.to_error_json(),
r#"{"code":"REMOTE_REQUIRES_REMOTE_EXIT_NODE"}"#
);
}
#[test]
fn an_exit_that_could_not_be_read_is_refused_too() {
// `Unknown` is "we could not confirm this works from elsewhere". Treating
// that as a yes reintroduces exactly the burned hour above, so it fails
// closed here as it does everywhere else `remote_exit` is consulted.
let refusal = local_exit_refusal(&ExitReachability::Unknown {
reason: "the profile references a proxy that no longer exists".to_string(),
source: "proxy",
})
.expect("an unreadable exit is not evidence of a reachable one");
assert_eq!(
refusal.to_error_json(),
r#"{"code":"REMOTE_REQUIRES_REMOTE_EXIT_NODE"}"#
);
}
#[test]
fn a_reachable_exit_and_no_exit_at_all_are_both_allowed_to_launch() {
assert!(local_exit_refusal(&ExitReachability::Remote).is_none());
// Deliberate, and the reason this gate is not simply `!is_remote()`: a
// proxyless interactive session has always been permitted, and refusing it
// with a code that says "your proxy is local" would be both a new product
// rule and a sentence that does not describe the profile.
assert!(local_exit_refusal(&ExitReachability::None).is_none());
}
#[test]
fn a_backend_supplied_code_survives_the_trip_through_the_typed_error() {
// Once infra sends an envelope, its code must win over the status default
// — "you are out of hours" and "the fleet is full" are both refusals but
// only one of them is worth retrying.
let err =
classify_error_string(r#"(403) {"code":"REMOTE_HOURS_EXHAUSTED","granted":200,"used":200}"#);
let json: serde_json::Value =
serde_json::from_str(&err.to_error_json()).expect("valid envelope");
assert_eq!(json["code"], "REMOTE_HOURS_EXHAUSTED");
assert_eq!(json["params"]["granted"], "200");
}
/// A verbatim `RemoteSessionView`, field for field, as `toView` in
/// donutbrowser-infra's `remote-sessions.service.ts` builds it.
///
/// Hand-written JSON is what let this type declare `status`, `ready_at` and
/// `closed_at` while the backend sent `state` and `ended_at`: the test agreed
/// with the type and neither agreed with the server, so every list and single
/// read failed to decode in production and passed in CI.
const SERVER_SESSION_VIEW: &str = r#"{
"session_id":"sess-1","profile_id":"p1","platform":"macos","kind":"cookie_bot",
"run_id":"r1","team_id":"t1","state":"live","cdp_ready":true,
"started_at":"2026-08-03T00:00:00.000Z","ended_at":null,
"billed_seconds":1830,"close_reason":null
}"#;
#[test]
fn the_session_state_payload_matches_what_the_backend_sends() {
// The desktop has been blind between launch and stop; every field here is
// one it could previously only learn by reading the production database.
let state: RemoteSessionState = serde_json::from_str(SERVER_SESSION_VIEW)
.expect("the backend's session payload must deserialize");
assert_eq!(state.state, "live");
assert!(state.cdp_ready);
assert_eq!(state.run_id.as_deref(), Some("r1"));
assert_eq!(state.team_id.as_deref(), Some("t1"));
assert_eq!(state.kind.as_deref(), Some("cookie_bot"));
assert_eq!(state.billed_seconds, Some(1830));
assert!(state.ended_at.is_none());
}
#[test]
fn a_list_response_of_real_server_views_decodes() {
// `list_remote_sessions` is the fallback for everything the stream cannot
// serve. It returned Err("decode response: missing field `status`") on
// every call for as long as this type disagreed with `toView`.
let body = format!(r#"{{"sessions":[{SERVER_SESSION_VIEW}]}}"#);
let response: RemoteSessionListResponse =
serde_json::from_str(&body).expect("the backend's list payload must deserialize");
assert_eq!(response.sessions.len(), 1);
assert_eq!(response.sessions[0].state, "live");
}
#[test]
fn the_older_status_key_from_the_launch_reply_still_decodes() {
// `POST /api/remote-sessions` predates the reconciled vocabulary and
// answers `status`. One type reads both rather than two types drifting.
let state: RemoteSessionState =
serde_json::from_str(r#"{"session_id":"s1","status":"provisioning"}"#)
.expect("a fresh session must deserialize");
assert_eq!(state.state, "provisioning");
assert!(!state.cdp_ready);
assert!(state.platform.is_none());
}
#[test]
fn a_close_transition_carries_what_the_session_cost() {
let state: RemoteSessionState = serde_json::from_str(
r#"{"session_id":"s1","state":"closed","close_reason":"stopped_by_user",
"ended_at":"2026-08-03T01:30:00.000Z","billed_seconds":1830}"#,
)
.expect("a close payload must deserialize");
assert_eq!(state.billed_seconds, Some(1830));
assert_eq!(state.close_reason.as_deref(), Some("stopped_by_user"));
assert!(state.ended_at.is_some());
}
#[test]
fn an_error_state_decodes_rather_than_being_treated_as_unknown() {
// `error` is one of the five states the backend reconciles to. A session
// that failed on the fleet must reach the UI as itself.
let state: RemoteSessionState =
serde_json::from_str(r#"{"session_id":"s1","state":"error","close_reason":"agent_lost"}"#)
.expect("an error payload must deserialize");
assert_eq!(state.state, "error");
}
#[test]
fn the_decoder_reads_a_whole_frame() {
let mut decoder = SseDecoder::new();
let frames = decoder.push(b"event: session\nid: 7\ndata: {\"status\":\"ready\"}\n\n");
assert_eq!(frames.len(), 1);
assert_eq!(frames[0].event.as_deref(), Some("session"));
assert_eq!(frames[0].id.as_deref(), Some("7"));
assert_eq!(frames[0].data, r#"{"status":"ready"}"#);
}
#[test]
fn a_frame_split_across_chunks_is_not_lost() {
// TCP does not respect frame boundaries. Dropping a half-arrived frame
// would silently lose the transition that says the browser is ready.
let mut decoder = SseDecoder::new();
assert!(decoder.push(b"event: session\ndata: {\"sta").is_empty());
assert!(decoder.push(b"tus\":\"live\"}").is_empty());
let frames = decoder.push(b"\n\n");
assert_eq!(frames.len(), 1);
assert_eq!(frames[0].data, r#"{"status":"live"}"#);
}
#[test]
fn several_frames_in_one_chunk_all_arrive() {
let mut decoder = SseDecoder::new();
let frames = decoder.push(b"data: 1\n\ndata: 2\n\ndata: 3\n\n");
let payloads: Vec<&str> = frames.iter().map(|f| f.data.as_str()).collect();
assert_eq!(payloads, vec!["1", "2", "3"]);
}
#[test]
fn comments_and_crlf_framing_do_not_produce_phantom_events() {
// A proxy that keeps the connection warm with `:` lines must not look
// like a stream of empty transitions.
let mut decoder = SseDecoder::new();
let frames = decoder.push(b": keep-alive\r\n\r\ndata: {}\r\n\r\n");
assert_eq!(frames.len(), 1);
assert_eq!(frames[0].data, "{}");
}
#[test]
fn multi_line_data_is_rejoined_with_newlines() {
let mut decoder = SseDecoder::new();
let frames = decoder.push(b"data: {\ndata: \"a\": 1\ndata: }\n\n");
assert_eq!(frames[0].data, "{\n\"a\": 1\n}");
}
/// Route whatever the decoder makes of a literal wire capture, so the test
/// exercises the same two steps production does.
fn route_wire(bytes: &[u8]) -> Vec<(&'static str, serde_json::Value)> {
let mut decoder = SseDecoder::new();
decoder
.push(bytes)
.iter()
.filter_map(|frame| route_frame(frame.event.as_deref(), &frame.data))
.collect()
}
#[test]
fn a_heartbeat_is_not_forwarded_to_the_frontend() {
// Emitting one would make every consumer re-render twice a minute for
// nothing. Nest names this one, so it arrives with an `event:` line.
assert!(route_wire(b"event: ping\ndata: {}\n\n").is_empty());
assert!(route_wire(b"event: heartbeat\ndata: {}\n\n").is_empty());
// And the same frame with the discriminator inside the JSON instead.
assert!(
route_wire(b"data: {\"type\":\"ping\",\"at\":\"2026-08-03T00:00:00.000Z\"}\n\n").is_empty()
);
}
#[test]
fn the_opening_snapshot_reaches_the_snapshot_event() {
// Byte-for-byte what Nest writes for `{type:'snapshot',at,sessions}`: no
// `event:` line, because the controller only sets MessageEvent.type for the
// ping. Routing on the event NAME sent this to `remote-session-state` as a
// raw envelope, so `remote-session-snapshot` was never emitted at all and
// the live view started empty and stayed empty.
let routed = route_wire(
b"data: {\"type\":\"snapshot\",\"at\":\"2026-08-03T00:00:00.000Z\",\"sessions\":[{\"session_id\":\"s1\",\"profile_id\":\"p1\",\"state\":\"live\"}]}\n\n",
);
assert_eq!(routed.len(), 1);
assert_eq!(routed[0].0, EVENT_SESSION_SNAPSHOT);
assert_eq!(routed[0].1["sessions"][0]["profile_id"], "p1");
}
#[test]
fn a_transition_is_unwrapped_to_the_session_the_frontend_indexes_by() {
// The consumer keys `liveSessions` by `profile_id`. Emitting the envelope
// meant every frame hit `if (!session.profile_id) return;` and a live run
// showed as idle for its whole duration.
for kind in ["state", "progress", "closed"] {
let wire = format!(
"data: {{\"type\":\"{kind}\",\"at\":\"2026-08-03T00:00:00.000Z\",\"session\":{{\"session_id\":\"s1\",\"profile_id\":\"p1\",\"state\":\"live\",\"cdp_ready\":true}}}}\n\n"
);
let routed = route_wire(wire.as_bytes());
assert_eq!(routed.len(), 1, "{kind} must produce one event");
assert_eq!(routed[0].0, EVENT_SESSION_STATE);
assert_eq!(routed[0].1["profile_id"], "p1", "{kind} must be unwrapped");
assert_eq!(routed[0].1["state"], "live");
// And the payload must deserialize as the type the one-shot reads use.
let session: RemoteSessionState = serde_json::from_value(routed[0].1.clone())
.expect("a streamed session must decode as RemoteSessionState");
assert_eq!(session.session_id, "s1");
}
}
#[test]
fn a_named_event_carrying_a_bare_session_is_still_routed() {
// If the backend starts labelling its frames and drops the envelope, the
// desktop must not need a release to keep working.
let routed = route_wire(
b"event: state\ndata: {\"session_id\":\"s1\",\"profile_id\":\"p1\",\"state\":\"ready\"}\n\n",
);
assert_eq!(routed.len(), 1);
assert_eq!(routed[0].0, EVENT_SESSION_STATE);
assert_eq!(routed[0].1["profile_id"], "p1");
let snapshot =
route_wire(b"event: snapshot\ndata: {\"type\":\"snapshot\",\"sessions\":[]}\n\n");
assert_eq!(snapshot[0].0, EVENT_SESSION_SNAPSHOT);
}
#[test]
fn a_frame_carrying_no_session_is_dropped_rather_than_emitted_raw() {
// Forwarding an envelope the consumer cannot apply is exactly the bug this
// routing exists to close; a malformed frame must be silent, not wrong.
assert!(
route_wire(b"data: {\"type\":\"state\",\"at\":\"2026-08-03T00:00:00.000Z\"}\n\n").is_empty()
);
assert!(route_wire(b"data: not json\n\n").is_empty());
assert!(route_wire(b"data: []\n\n").is_empty());
}
#[test]
fn reconnect_backs_off_and_stops_growing() {
assert_eq!(reconnect_delay(0), Duration::from_secs(1));
assert_eq!(reconnect_delay(3), Duration::from_secs(8));
// A backend that is down for an hour must not be probed thousands of
// times, nor overflow the shift.
assert_eq!(reconnect_delay(20), RECONNECT_MAX);
assert_eq!(reconnect_delay(u32::MAX), RECONNECT_MAX);
}
#[test]
fn the_auth_backoff_floor_is_far_longer_than_the_first_retry() {
// Being signed out or unentitled is not fixed by retrying in a second.
assert!(reconnect_delay(AUTH_BACKOFF_ATTEMPT) >= Duration::from_secs(30));
}
#[test]
fn jitter_stays_within_a_fifth_of_the_delay() {
let base = Duration::from_secs(10);
for _ in 0..64 {
let delay = jittered(base);
assert!(
delay >= Duration::from_secs(8) && delay <= Duration::from_secs(12),
"jitter escaped its bounds: {delay:?}"
);
}
}
#[tokio::test]
async fn a_stopped_stream_does_not_wait_out_its_backoff() {
// A minute-long backoff must not hold up app shutdown.
STREAM_RUNNING.store(true, Ordering::SeqCst);
let started = std::time::Instant::now();
let sleeper = tokio::spawn(sleep_unless_stopped(Duration::from_secs(60)));
tokio::time::sleep(Duration::from_millis(50)).await;
STREAM_RUNNING.store(false, Ordering::SeqCst);
sleeper.await.expect("the sleep task must finish");
assert!(
started.elapsed() < Duration::from_secs(5),
"shutdown waited on the backoff"
);
}
#[test]
fn stopping_a_stream_that_never_started_is_harmless() {
STREAM_RUNNING.store(false, Ordering::SeqCst);
stop_session_events();
assert!(!session_events_running());
}
// --- The drivable-session index ------------------------------------------
//
// This index is what lets an automation call decide "is this profile running
// on the fleet?" without a cloud round trip. Everything below drives it
// through the SAME two steps production uses — decode the wire, route the
// frame, apply it — because the whole class of bug this replaced came from a
// test that agreed with the client and neither agreeing with the server.
/// The statics below are process-wide, and `cargo test` runs these threads in
/// parallel. Without this every index test would be racing every other one.
static INDEX_TESTS: Mutex<()> = Mutex::new(());
fn index_test<T>(body: impl FnOnce() -> T) -> T {
let _guard = INDEX_TESTS
.lock()
.unwrap_or_else(std::sync::PoisonError::into_inner);
// Applying a session transition also drives `remote_handoff`: it mutates
// that module's process-global store and persists the launch gate to the
// data directory. Its lock keeps the two test groups from clobbering each
// other's `p1`/`p2` fixtures, and the scratch directory keeps the gate file
// out of the developer's own app data.
let _handoff = crate::remote_handoff::lock_for_test();
let dir = tempfile::TempDir::new().expect("a scratch directory");
let _data_dir = crate::app_dirs::set_test_data_dir(dir.path().to_path_buf());
with_index(|map| map.clear());
with_endpoints(|map| map.clear());
INDEX_AUTHORITATIVE.store(false, Ordering::SeqCst);
body()
}
/// Decode, route and apply a literal wire capture, exactly as
/// `dispatch_frame` does minus the emit to the frontend.
fn feed(bytes: &[u8]) {
let mut decoder = SseDecoder::new();
for frame in decoder.push(bytes) {
if let Some((target, payload)) = route_frame(frame.event.as_deref(), &frame.data) {
apply_to_index(None, target, &payload);
}
}
}
fn indexed(profile_id: &str) -> Option<RemoteSessionState> {
with_index(|map| map.get(profile_id).cloned())
}
fn transition(session_id: &str, profile_id: &str, state: &str, cdp_ready: bool) -> Vec<u8> {
format!(
"data: {{\"type\":\"state\",\"session\":{{\"session_id\":\"{session_id}\",\"profile_id\":\"{profile_id}\",\"state\":\"{state}\",\"cdp_ready\":{cdp_ready}}}}}\n\n"
)
.into_bytes()
}
#[test]
fn a_session_becoming_drivable_is_indexed_by_the_profile_it_holds() {
index_test(|| {
feed(&transition("sess-1", "p1", "live", true));
let held = indexed("p1").expect("a live session must be resolvable by profile");
assert_eq!(held.session_id, "sess-1");
});
}
#[test]
fn a_browser_that_is_up_but_not_attachable_is_not_offered_for_driving() {
index_test(|| {
// `ready` without CDP is a browser that exists and cannot be driven.
// Offering it is what makes a client attach into a connection that never
// establishes, and then blame the fleet for the timeout.
feed(&transition("sess-1", "p1", "ready", false));
assert!(indexed("p1").is_none());
feed(&transition("sess-1", "p1", "provisioning", false));
assert!(indexed("p1").is_none());
});
}
#[test]
fn a_session_that_closes_frees_the_profile_and_forgets_its_endpoint() {
index_test(|| {
feed(&transition("sess-1", "p1", "live", true));
with_endpoints(|map| {
map.insert(
"sess-1".to_string(),
CdpEndpoint {
session_id: "sess-1".to_string(),
ws_url: "wss://example/cdp".to_string(),
protocol: PROTOCOL_CDP_RELAY_1.to_string(),
auth: AUTH_BEARER.to_string(),
},
)
});
feed(&transition("sess-1", "p1", "closed", false));
assert!(indexed("p1").is_none());
// A cached endpoint for a dead session would be handed to the next
// attach, which would then fail against a relay that has nothing left to
// relay to.
assert!(with_endpoints(|map| map.get("sess-1").cloned()).is_none());
});
}
#[test]
fn a_late_close_for_a_finished_session_does_not_evict_the_one_that_replaced_it() {
index_test(|| {
feed(&transition("sess-1", "p1", "live", true));
feed(&transition("sess-1", "p1", "closed", false));
feed(&transition("sess-2", "p1", "live", true));
// Out-of-order frames are normal: the reconciler polls the fleet while
// the user is already starting the next session. A stale close arriving
// after the new session went live must not make a working browser
// unreachable.
feed(&transition("sess-1", "p1", "closed", false));
assert_eq!(
indexed("p1").map(|s| s.session_id),
Some("sess-2".to_string())
);
});
}
#[test]
fn the_opening_snapshot_replaces_the_index_and_makes_it_authoritative() {
index_test(|| {
feed(&transition("stale", "p-gone", "live", true));
feed(
concat!(
r#"data: {"type":"snapshot","at":"2026-08-03T00:00:00.000Z","sessions":["#,
r#"{"session_id":"sess-1","profile_id":"p1","state":"live","cdp_ready":true},"#,
r#"{"session_id":"sess-2","profile_id":"p2","state":"ready","cdp_ready":false}]}"#,
"\n\n"
)
.as_bytes(),
);
assert_eq!(
indexed("p1").map(|s| s.session_id),
Some("sess-1".to_string())
);
// Not attachable, so not in the index even though the snapshot listed it.
assert!(indexed("p2").is_none());
// A session the snapshot did not mention is gone, however live the index
// last believed it to be.
assert!(indexed("p-gone").is_none());
assert!(INDEX_AUTHORITATIVE.load(Ordering::SeqCst));
});
}
#[test]
fn a_snapshot_carrying_no_session_list_does_not_blind_the_resolver() {
index_test(|| {
feed(&transition("sess-1", "p1", "live", true));
// Trusting a malformed snapshot would answer "no session" for every
// profile until the next reconnect, which is exactly the blindness the
// index exists to remove.
apply_to_index(None, EVENT_SESSION_SNAPSHOT, &serde_json::json!({}));
assert_eq!(
indexed("p1").map(|s| s.session_id),
Some("sess-1".to_string())
);
assert!(!INDEX_AUTHORITATIVE.load(Ordering::SeqCst));
});
}
#[test]
fn one_undecodable_session_does_not_cost_the_whole_snapshot() {
index_test(|| {
feed(
concat!(
r#"data: {"type":"snapshot","sessions":[{"nonsense":true},"#,
r#"{"session_id":"sess-1","profile_id":"p1","state":"live","cdp_ready":true}]}"#,
"\n\n"
)
.as_bytes(),
);
assert_eq!(
indexed("p1").map(|s| s.session_id),
Some("sess-1".to_string())
);
assert!(INDEX_AUTHORITATIVE.load(Ordering::SeqCst));
});
}
#[test]
fn unsubscribing_stops_the_index_being_an_answer() {
index_test(|| {
INDEX_AUTHORITATIVE.store(true, Ordering::SeqCst);
STREAM_RUNNING.store(false, Ordering::SeqCst);
// Sign-out unsubscribes. An index still marked authoritative would keep
// answering from state nothing is maintaining any more, so a session
// started by the next account would report as absent.
stop_session_events();
assert!(!INDEX_AUTHORITATIVE.load(Ordering::SeqCst));
});
}
#[test]
fn a_session_with_no_profile_is_ignored_rather_than_indexed_under_nothing() {
index_test(|| {
feed(b"data: {\"type\":\"state\",\"session\":{\"session_id\":\"s1\",\"state\":\"live\",\"cdp_ready\":true}}\n\n");
assert!(with_index(|map| map.is_empty()));
});
}
// --- The CDP endpoint descriptor -----------------------------------------
#[test]
fn the_endpoint_descriptor_matches_what_the_backend_sends() {
// Pinned against `GET /api/remote-sessions/:id/cdp` in donutbrowser-infra.
// A field name that does not match makes every remote attach fail at the
// decode step, and the desktop reports a live session as undrivable.
let endpoint: CdpEndpoint = serde_json::from_str(
r#"{"session_id":"sess-1",
"ws_url":"wss://api.donutbrowser.com/api/remote-sessions/cdp?session_id=sess-1",
"protocol":"cdp-relay/1","auth":"bearer"}"#,
)
.expect("the backend's CDP descriptor must deserialize");
assert_eq!(endpoint.session_id, "sess-1");
assert!(endpoint.ws_url.starts_with("wss://"));
assert!(unsupported_descriptor(&endpoint).is_none());
}
#[test]
fn a_descriptor_this_build_cannot_honour_is_refused_rather_than_guessed_at() {
// The descriptor is opaque and server-decided so the endpoint can move
// without a desktop release. The other side of that bargain is that a
// scheme this build does not implement must say so, not present the user's
// access token on a wire that expected something else.
let ticketed = CdpEndpoint {
session_id: "sess-1".to_string(),
ws_url: "wss://fleet.example/cdp".to_string(),
protocol: PROTOCOL_CDP_RELAY_1.to_string(),
auth: "ticket".to_string(),
};
assert!(unsupported_descriptor(&ticketed)
.expect("an unknown auth scheme must be refused")
.contains("update Donut Browser"));
let future_protocol = CdpEndpoint {
auth: AUTH_BEARER.to_string(),
protocol: "cdp-relay/2".to_string(),
..ticketed
};
assert!(unsupported_descriptor(&future_protocol).is_some());
}
#[test]
fn a_descriptor_that_states_nothing_is_treated_as_todays_behaviour() {
// An older backend that predates the fields must keep working; the fields
// are a forward-compatibility hook, not a required handshake.
let bare: CdpEndpoint = serde_json::from_str(r#"{"ws_url":"wss://example/cdp"}"#)
.expect("a descriptor with only a URL must deserialize");
assert!(bare.session_id.is_empty());
assert!(unsupported_descriptor(&bare).is_none());
}
#[test]
fn only_a_session_that_is_both_live_and_attachable_is_drivable() {
let mut session: RemoteSessionState =
serde_json::from_str(r#"{"session_id":"s1","state":"live","cdp_ready":true}"#).unwrap();
assert!(is_drivable(&session));
session.cdp_ready = false;
assert!(!is_drivable(&session));
session.cdp_ready = true;
session.state = "ready".to_string();
assert!(!is_drivable(&session));
}
}