Add timeout to MCP tools/prompts/resources listing

Servers that advertise a capability but never answer the list request
(e.g. prompts/list) parked the init thread forever on an untimed deref,
leaving the server stuck in starting state. Pass mcpTimeoutSeconds to
the plumcp list calls and fall back to an empty list on timeout.

Author: ericdallo

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Apply `mcpTimeoutSeconds` to MCP tools/prompts/resources listing, avoiding servers stuck in `starting` state when a list request never gets a response.
+
 ## 0.153.0
 
 - Store chats in per-chat cache files with a lazy-loaded index instead of one whole-workspace blob, fixing CPU spikes and slow startup as history grows; legacy caches migrate automatically. #557

src/eca/features/tools/mcp.clj

@@ -326,22 +326,33 @@
     (logger/warn logger-tag (format "Could not list %s: %s" kind (format-jsonrpc-error jsonrpc-error)))
     []))
 
-(defn ^:private list-server-tools [client]
+(defn ^:private on-list-timeout [kind]
+  (fn [_id _timeout-value]
+    (logger/warn logger-tag (format "Timeout waiting server response listing %s" kind))
+    []))
+
+(defn ^:private list-options [kind timeout-ms]
+  {:on-error (on-list-error kind)
+   :timeout-millis timeout-ms
+   :timeout-value ::list-timeout
+   :on-timeout (on-list-timeout kind)})
+
+(defn ^:private list-server-tools [client timeout-ms]
   (if (get-in (pmc/get-initialize-result client) [:capabilities :tools])
-    (or (some->> (pmc/list-tools client {:on-error (on-list-error "tools")})
+    (or (some->> (pmc/list-tools client (list-options "tools" timeout-ms))
                  (mapv tool->internal))
         [])
     []))
 
-(defn ^:private list-server-prompts [client]
+(defn ^:private list-server-prompts [client timeout-ms]
   (if (get-in (pmc/get-initialize-result client) [:capabilities :prompts])
-    (or (pmc/list-prompts client {:on-error (on-list-error "prompts")})
+    (or (pmc/list-prompts client (list-options "prompts" timeout-ms))
         [])
     []))
 
-(defn ^:private list-server-resources [client]
+(defn ^:private list-server-resources [client timeout-ms]
   (if (get-in (pmc/get-initialize-result client) [:capabilities :resources])
-    (or (pmc/list-resources client {:on-error (on-list-error "resources")})
+    (or (pmc/list-resources client (list-options "resources" timeout-ms))
         [])
     []))
 
@@ -453,6 +464,7 @@
                                 server-config
                                 {:on-server-updated on-server-updated})
           (let [init-timeout (:mcpTimeoutSeconds config)
+                list-timeout-ms (* 1000 init-timeout)
                 pending-tools-refresh* (atom nil)
                 on-tools-change (fn [tools]
                                   (let [tools (mapv tool->internal tools)]
@@ -479,9 +491,9 @@
                                                                          http-client (assoc :http-client http-client)))
                                (swap! db* assoc-in [:mcp-clients name :version] version)
                                (swap! db* assoc-in [:mcp-clients name :instructions] (:instructions init-result))
-                               (swap! db* assoc-in [:mcp-clients name :tools] (list-server-tools client))
-                               (swap! db* assoc-in [:mcp-clients name :prompts] (list-server-prompts client))
-                               (swap! db* assoc-in [:mcp-clients name :resources] (list-server-resources client))
+                               (swap! db* assoc-in [:mcp-clients name :tools] (list-server-tools client list-timeout-ms))
+                               (swap! db* assoc-in [:mcp-clients name :prompts] (list-server-prompts client list-timeout-ms))
+                               (swap! db* assoc-in [:mcp-clients name :resources] (list-server-resources client list-timeout-ms))
                                (if (and needs-reinit?* @needs-reinit?*)
                                  (do (try (pp/stop-client-transport! transport false) (catch Exception _))
                                      (if (< attempt max-init-retries)