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fix: simplify MCP STDIO reconnection by closing client before reconnect #11887

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fix: simplify MCP STDIO reconnection by closing client before reconnect #11887

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871b7c5
fix: simplify MCP STDIO reconnection by closing client before reconnect
yaruchyo Mar 26, 2026
cf55775
fix: resolve MCP reconnection 'Already connected to a transport' error
yaruchyo Mar 26, 2026
db3d590
fix: preserve Client instance on reconnect, fallback to fresh Client …
yaruchyo Mar 26, 2026
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38 changes: 17 additions & 21 deletions core/context/mcp/MCPConnection.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -85,7 +85,13 @@ class MCPConnection {
// Don't construct transport in constructor to avoid blocking
this.transport = {} as Transport; // Will be set in connectClient

this.client = new Client(
this.client = this.createClient();

this.abortController = new AbortController();
}

private createClient(): Client {
return new Client(
{
name: "continue-client",
version: "1.0.0",
Expand All @@ -94,8 +100,6 @@ class MCPConnection {
capabilities: {},
},
);

this.abortController = new AbortController();
}

async disconnect(disable = false) {
Expand Down Expand Up @@ -213,29 +217,20 @@ Org-level secrets can only be used for MCP by Background Agents (https://docs.co
});
}),
(async () => {
try {
await this.client.close();
} catch {
// Best-effort cleanup; may fail if never connected
}
this.client = this.createClient();

if ("command" in this.options) {
// STDIO: no need to check type, just if command is present
const transport = await this.constructStdioTransport(
this.options,
);
try {
await this.client.connect(transport, {});
this.transport = transport;
} catch (error) {
// Allow the case where for whatever reason is already connected
if (
error instanceof Error &&
error.message.startsWith(
"StdioClientTransport already started",
)
) {
await this.client.close();
await this.client.connect(transport);
this.transport = transport;
} else {
throw error;
}
}
await this.client.connect(transport, {});
this.transport = transport;
} else {
// SSE/HTTP: if type isn't explicit: try http and fall back to sse
if (this.options.type === "sse") {
Expand Down Expand Up @@ -265,6 +260,7 @@ Org-level secrets can only be used for MCP by Background Agents (https://docs.co
await this.client.connect(transport, {});
this.transport = transport;
} catch (e) {
this.client = this.createClient();
try {
const transport = this.constructSseTransport({
...this.options,
Expand Down
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