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//!
//! Apps clients read the provider's current catalog without retaining old arrays.
//! Only active readers, calls, and frozen model bindings pin earlier snapshots.
//! Explicit refreshes publish after calls using this client's current revision finish.
//! Equivalent shared publications preserve calls, but explicit refreshes invalidate them.
use std::collections::HashSet;
use std::future::Future;
use std::sync::Arc;
use anyhow::Result;
use codex_connectors::ConnectorRuntimeSnapshot;
use tokio::sync::Mutex;
use tokio::sync::RwLock;
use tokio::sync::RwLockReadGuard;
use tokio::sync::watch;
use crate::tools::ToolInfo;
type ToolCatalogUpdates = watch::Receiver<Option<Arc<ConnectorRuntimeSnapshot<ToolInfo>>>>;
/// The exact Apps catalog returned by an awaited refresh of one published runtime.
pub struct CodexAppsToolSnapshot {
/// Raw installed tools, including tools hidden or disabled for the model.
pub tools: Vec<ToolInfo>,
/// Raw MCP tool names allowed by the same runtime's generic MCP policy.
/// App-specific policy is applied by the caller.
pub model_visible_tool_names: HashSet<String>,
}
pub(crate) struct ClientToolCatalog {
current: RwLock<CatalogState>,
/// Serialize fetches without blocking calls against the current catalog.
refresh_lock: Mutex<()>,
}
struct CatalogState {
revision: u64,
/// The catalog revision installed by this client's last explicit refresh.
last_refresh_revision: u64,
source: CatalogSource,
}
/// Ordinary MCP clients own their tools; Apps clients observe the shared provider.
enum CatalogSource {
Local(Arc<[ToolInfo]>),
Live {
updates: ToolCatalogUpdates,
tools_version: u64,
},
}
pub(crate) struct ToolCatalogSnapshot {
pub(crate) revision: u64,
pub(crate) tools: Arc<[ToolInfo]>,
}
impl ClientToolCatalog {
/// Live clients read the provider; callers publish startup tools before subscribing.
pub(crate) fn new(
tools: impl Into<Arc<[ToolInfo]>>,
updates: Option<ToolCatalogUpdates>,
) -> Self {
let source = match updates {
Some(mut updates) => {
let tools_version = updates
.borrow_and_update()
.as_ref()
.map_or(0, |snapshot| snapshot.tools_version());
CatalogSource::Live {
updates,
tools_version,
}
}
None => CatalogSource::Local(tools.into()),
};
Self {
current: RwLock::new(CatalogState {
revision: 0,
last_refresh_revision: 0,
source,
}),
refresh_lock: Mutex::new(()),
}
}
pub(crate) async fn read<R>(&self, read: impl FnOnce(ToolCatalogSnapshot) -> R) -> R {
let (_current, snapshot) = self.read_current().await;
read(snapshot)
}
/// Captures tools and their client-local revision together, without retaining them in the client.
async fn read_current(&self) -> (RwLockReadGuard<'_, CatalogState>, ToolCatalogSnapshot) {
loop {
{
let current = self.current.read().await;
let tools = match ¤t.source {
CatalogSource::Local(tools) => Some(Arc::clone(tools)),
CatalogSource::Live { updates, .. } => {
// Hold the watch borrow while checking its version so the tools and
// revision come from the same publication.
let snapshot = updates.borrow();
(!updates.has_changed().unwrap_or(false)).then(|| {
snapshot
.as_ref()
.map(|snapshot| snapshot.shared_tools())
.unwrap_or_default()
})
}
};
if let Some(tools) = tools {
let snapshot = ToolCatalogSnapshot {
revision: current.revision,
tools,
};
return (current, snapshot);
}
}
let mut current = self.current.write().await;
let changed = match &mut current.source {
CatalogSource::Live {
updates,
tools_version,
} => {
let version = updates
.borrow_and_update()
.as_ref()
.map_or(0, |snapshot| snapshot.tools_version());
let changed = *tools_version != version;
*tools_version = version;
changed
}
CatalogSource::Local(_) => false,
};
if changed {
current.revision += 1;
}
}
}
/// Serialize fetching and publication, leaving the current catalog usable during the fetch.
/// The publication callback runs alongside the exact-client update under the write lock.
#[expect(
clippy::await_holding_invalid_type,
reason = "refreshes must remain serialized through fetching and catalog publication"
)]
pub(crate) async fn refresh<C, R, F, Fut, P>(&self, fetch: F, publish: P) -> Result<R>
where
F: FnOnce() -> Fut,
Fut: Future<Output = Result<(Vec<ToolInfo>, C)>>,
P: FnOnce(&[ToolInfo], C) -> R,
{
let _refresh = self.refresh_lock.lock().await;
let (tools, context) = fetch().await?;
let mut current = self.current.write().await;
let result = publish(&tools, context);
match &mut current.source {
CatalogSource::Local(current_tools) => *current_tools = tools.into(),
CatalogSource::Live {
updates,
tools_version,
} => {
*tools_version = updates
.borrow_and_update()
.as_ref()
.map_or(0, |snapshot| snapshot.tools_version());
}
}
current.revision += 1;
current.last_refresh_revision = current.revision;
Ok(result)
}
/// Reject stale calls before preparation and hold catalog authority until execution finishes.
#[expect(
clippy::await_holding_invalid_type,
reason = "catalog publication must wait for call preparation and execution"
)]
pub(crate) async fn run_with_snapshot<R, F, Fut>(
&self,
expected: &ToolCatalogSnapshot,
run: F,
) -> Option<R>
where
F: FnOnce() -> Fut,
Fut: Future<Output = R>,
{
let (current, snapshot) = self.read_current().await;
if current.last_refresh_revision > expected.revision
|| (snapshot.revision != expected.revision
&& !catalogs_match(&snapshot.tools, &expected.tools))
{
return None;
}
let result = run().await;
drop(current);
Some(result)
}
}
/// Compares complete definitions independently of tool-list order. Stable sorting keeps
/// conflicting duplicate identities in their original order, since deduplication can pick the
/// first definition. This slow path runs only after the client's revision has changed.
fn catalogs_match(left: &[ToolInfo], right: &[ToolInfo]) -> bool {
if left == right {
return true;
}
if left.len() != right.len() {
return false;
}
let mut left = left.iter().collect::<Vec<_>>();
let mut right = right.iter().collect::<Vec<_>>();
for tools in [&mut left, &mut right] {
tools.sort_by_key(|tool| {
(
tool.server_name.as_str(),
tool.tool.name.as_ref(),
tool.connector_id.as_deref(),
tool.callable_namespace.as_str(),
tool.callable_name.as_str(),
)
});
}
left == right
}
/// A binding cache key includes client identity, since new clients start at zero.
#[derive(Clone)]
pub(crate) struct ClientToolCatalogRevision {
pub(crate) catalog: Arc<ClientToolCatalog>,
pub(crate) revision: u64,
}
impl PartialEq for ClientToolCatalogRevision {
fn eq(&self, other: &Self) -> bool {
Arc::ptr_eq(&self.catalog, &other.catalog) && self.revision == other.revision
}
}
impl Eq for ClientToolCatalogRevision {}
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