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Record why an MCP request was cut off with "session was reset" #8

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Merged
fforres merged 1 commit into from
Sep 26, 2026
Merged

Record why an MCP request was cut off with "session was reset" #8

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76 changes: 31 additions & 45 deletions patches/agents@0.17.3.patch
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Original file line number Diff line number Diff line change
@@ -1,18 +1,3 @@
diff --git a/node_modules/agents/.bun-tag-37e67b70862be2b2 b/.bun-tag-37e67b70862be2b2
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/node_modules/agents/.bun-tag-61b2f1517ab5ced4 b/.bun-tag-61b2f1517ab5ced4
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/node_modules/agents/.bun-tag-61d29b56a6079f1d b/.bun-tag-61d29b56a6079f1d
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/node_modules/agents/.bun-tag-a6a47855632a2623 b/.bun-tag-a6a47855632a2623
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/node_modules/agents/.bun-tag-c0c639aa2299e502 b/.bun-tag-c0c639aa2299e502
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/dist/agent-tool-types-CNyE1iz_.d.ts b/dist/agent-tool-types-CNyE1iz_.d.ts
index 571eececebd5a1eaf7f2fbf5278801c4d34728ba..010811ae74ef2d27f12f7fb2506848f1939d91d6 100644
--- a/dist/agent-tool-types-CNyE1iz_.d.ts
Expand Down Expand Up @@ -95,7 +80,7 @@ index c8fad448e8797b89690a99d93490d1363851b225..d80f66f1532c29dda0a0477dc1ec9ef5
McpAgent,
type McpAuthContext,
diff --git a/dist/mcp/index.js b/dist/mcp/index.js
index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c28786cca392 100644
index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..c661da89ea510827af5bf6a374eed0768462f640 100644
--- a/dist/mcp/index.js
+++ b/dist/mcp/index.js
@@ -28,13 +28,60 @@ import { WebStandardStreamableHTTPServerTransport } from "@modelcontextprotocol/
Expand Down Expand Up @@ -196,7 +181,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
request.headers.forEach((value, key) => {
existingHeaders[key] = value;
});
@@ -206,47 +273,159 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
@@ -206,47 +273,160 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
jsonrpc: "2.0"
});
return new Response(body, { status: 500 });
Expand Down Expand Up @@ -276,7 +261,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
+ * The happy path is byte-identical: every id has been reported
+ * responded by then, so the set is empty and nothing is written.
+ */
+ const __finishAbnormally = async (reason) => {
+ const __finishAbnormally = async (reason, detail = {}) => {
+ if (__finished) return;
+ __finished = true;
+ clearTimeout(__responseDeadline);
Expand All @@ -286,7 +271,8 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
+ event: "mcp_post_stream_lost",
+ outstandingCount: __outstanding.size,
+ reason,
+ sessionId
+ sessionId,
+ ...detail
+ }));
+ for (const id of __outstanding.values()) __forwardSse(encoder.encode(`event: message\ndata: ${JSON.stringify(sessionResetErrorResponse(id, reason))}\n\n`));
+ __outstanding.clear();
Expand Down Expand Up @@ -351,7 +337,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
+ async function onError(_error) {
+ // The DO end of the bridge failed. Nothing still
+ // outstanding will ever be answered.
+ await __finishAbnormally("session_reset");
+ await __finishAbnormally("session_reset", { bridge: "error", error: String(_error?.message ?? _error ?? "") });
}
onError(error).catch(console.error);
});
Expand All @@ -376,14 +362,14 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
+ await writer.close().catch(() => {});
+ return;
+ }
+ await __finishAbnormally("session_reset");
+ await __finishAbnormally("session_reset", { bridge: "close", closeCode: closeEvent?.code ?? null, closeReason: closeEvent?.reason ?? null, wasClean: closeEvent?.wasClean ?? null });
}
- onClose().catch(console.error);
+ onClose(event).catch(console.error);
});
return new Response(readable, {
headers: {
@@ -279,10 +458,16 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
@@ -279,10 +459,16 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
id: null,
jsonrpc: "2.0"
}), { status: 400 });
Expand All @@ -404,7 +390,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
props: ctx.props,
jurisdiction: options.jurisdiction
});
@@ -306,27 +491,116 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
@@ -306,27 +492,116 @@ const createStreamingHttpHandler = (basePath, namespace, options = {}) => {
if (!ws) {
await writer.close();
return new Response("Failed to establish WS to DO", { status: 500 });
Expand Down Expand Up @@ -536,7 +522,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
return new Response(readable, {
headers: {
"Cache-Control": "no-cache",
@@ -389,10 +663,16 @@ const createLegacySseHandler = (basePath, namespace, options = {}) => {
@@ -389,10 +664,16 @@ const createLegacySseHandler = (basePath, namespace, options = {}) => {
const url = new URL(request.url);
if (request.method === "GET" && basePattern.test(url)) {
const sessionId = url.searchParams.get("sessionId") || namespace.newUniqueId().toString();
Expand All @@ -557,7 +543,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
endpointUrl.pathname = encodeURI(`${basePath}/message`);
endpointUrl.searchParams.set("sessionId", sessionId);
const endpointMessage = `event: endpoint\ndata: ${endpointUrl.pathname + endpointUrl.search + endpointUrl.hash}\n\n`;
@@ -414,35 +694,94 @@ const createLegacySseHandler = (basePath, namespace, options = {}) => {
@@ -414,35 +695,94 @@ const createLegacySseHandler = (basePath, namespace, options = {}) => {
console.error("Failed to establish WebSocket connection");
await writer.close();
return new Response("Failed to establish WebSocket connection", { status: 500 });
Expand Down Expand Up @@ -670,7 +656,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
console.error("Error closing SSE connection:", error);
}
}
@@ -586,6 +925,8 @@ var StreamableHTTPServerTransport = class {
@@ -586,6 +926,8 @@ var StreamableHTTPServerTransport = class {
constructor(options) {
this._started = false;
this._streamResponseIds = /* @__PURE__ */ new Map();
Expand All @@ -679,7 +665,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
const { agent } = getCurrentAgent();
if (!agent) throw new Error("McpAgent was not found in Transport constructor");
this._agent = agent;
@@ -627,23 +968,146 @@ var StreamableHTTPServerTransport = class {
@@ -627,23 +969,146 @@ var StreamableHTTPServerTransport = class {
const resumedStreamId = await this._eventStore.getStreamIdForEventId?.(lastEventId);
if (resumedStreamId) {
const resumeState = { streamId: resumedStreamId };
Expand Down Expand Up @@ -832,7 +818,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
}
/**
* Close any connection (other than `selfId`) currently bound to
@@ -651,6 +1115,9 @@ var StreamableHTTPServerTransport = class {
@@ -651,6 +1116,9 @@ var StreamableHTTPServerTransport = class {
* Closing rather than mutating sibling state mirrors how the SDK's
* single `_streamMapping` entry gives last-writer-wins for free, and
* keeps `send()` from routing to a stale bridge.
Expand All @@ -842,7 +828,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
*/
supersedePriorStreamConnections(agent, selfId, streamId) {
for (const other of agent.getConnections()) {
@@ -664,12 +1131,14 @@ var StreamableHTTPServerTransport = class {
@@ -664,12 +1132,14 @@ var StreamableHTTPServerTransport = class {
* Only used when resumability is enabled
*/
async replayEvents(lastEventId) {
Expand All @@ -858,7 +844,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
this.writeSSEEvent(connection, message, eventId);
} catch (error) {
this.onerror?.(error);
@@ -678,6 +1147,45 @@ var StreamableHTTPServerTransport = class {
@@ -678,6 +1148,45 @@ var StreamableHTTPServerTransport = class {
} catch (error) {
this.onerror?.(error);
}
Expand Down Expand Up @@ -904,7 +890,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
}
/**
* Writes an event to the SSE stream with proper formatting
@@ -689,10 +1197,69 @@ var StreamableHTTPServerTransport = class {
@@ -689,10 +1198,69 @@ var StreamableHTTPServerTransport = class {
return connection.send(JSON.stringify({
type: "cf_mcp_agent_event",
event: eventData,
Expand Down Expand Up @@ -974,7 +960,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
* Handles POST requests containing JSON-RPC messages
*/
async handlePostRequest(req, parsedBody) {
@@ -733,6 +1300,22 @@ var StreamableHTTPServerTransport = class {
@@ -733,6 +1301,22 @@ var StreamableHTTPServerTransport = class {
};
connection.setState(postState);
if (this._eventStore) await agent.setStreamRequestIds(streamId, requestIds);
Expand All @@ -997,7 +983,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
for (const message of messages) {
if (this.messageInterceptor) {
if (await this.messageInterceptor(message, {
@@ -760,7 +1343,22 @@ var StreamableHTTPServerTransport = class {
@@ -760,7 +1344,22 @@ var StreamableHTTPServerTransport = class {
* when the originating WS has dropped.
*/
async sendOnStream(agent, streamId, relatedIds, liveConnection, message, requestId) {
Expand All @@ -1021,7 +1007,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
let shouldClose = false;
if (isJSONRPCResultResponse(message) || isJSONRPCErrorResponse(message)) {
let responseIds = this._streamResponseIds.get(streamId);
@@ -777,9 +1375,11 @@ var StreamableHTTPServerTransport = class {
@@ -777,9 +1376,11 @@ var StreamableHTTPServerTransport = class {
} catch (error) {
this.onerror?.(error);
}
Expand All @@ -1035,7 +1021,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
}
}
async send(message, options) {
@@ -798,14 +1398,19 @@ var StreamableHTTPServerTransport = class {
@@ -798,14 +1399,19 @@ var StreamableHTTPServerTransport = class {
*
* Sent on exactly one stream, per MCP: "the server MUST send each of
* its JSON-RPC messages on only one of the connected streams; it MUST
Expand All @@ -1059,7 +1045,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
if (standalone) this.writeSSEEvent(standalone, message, eventId);
}
/**
@@ -861,12 +1466,10 @@ var StreamableHTTPServerTransport = class {
@@ -861,12 +1467,10 @@ var StreamableHTTPServerTransport = class {
*
* ## Lifecycle
*
Expand All @@ -1076,7 +1062,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
*
* Standalone GET stream events (`_GET_stream`) are *not* cleared
* automatically; they accumulate for the lifetime of the DO. Bounded
@@ -893,12 +1496,34 @@ var DurableObjectEventStore = class DurableObjectEventStore {
@@ -893,12 +1497,34 @@ var DurableObjectEventStore = class DurableObjectEventStore {
}
async storeEvent(streamId, message) {
if (streamId.includes(":")) throw new Error(`DurableObjectEventStore: streamId must not contain ':' (got ${JSON.stringify(streamId)})`);
Expand Down Expand Up @@ -1111,7 +1097,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
return eventId;
}
async getStreamIdForEventId(eventId) {
@@ -915,9 +1540,59 @@ var DurableObjectEventStore = class DurableObjectEventStore {
@@ -915,9 +1541,59 @@ var DurableObjectEventStore = class DurableObjectEventStore {
start: startKey,
limit: DurableObjectEventStore.REPLAY_LIMIT
});
Expand Down Expand Up @@ -1172,7 +1158,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
/**
* Drop the event log for a single stream. Called by the transport
* immediately after a POST's final response has been written to the
@@ -973,6 +1648,13 @@ DurableObjectEventStore.EVENT_KEY_PREFIX = "__mcp_event__:";
@@ -973,6 +1649,13 @@ DurableObjectEventStore.EVENT_KEY_PREFIX = "__mcp_event__:";
DurableObjectEventStore.SEQ_PAD = 16;
DurableObjectEventStore.DELETE_CHUNK = 128;
DurableObjectEventStore.REPLAY_LIMIT = 1e3;
Expand All @@ -1186,7 +1172,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
//#endregion
//#region src/mcp/client-transports.ts
/**
@@ -1355,6 +2037,26 @@ function experimental_createMcpHandler(server, options = {}) {
@@ -1355,6 +2038,26 @@ function experimental_createMcpHandler(server, options = {}) {
}
//#endregion
//#region src/mcp/index.ts
Expand All @@ -1213,7 +1199,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
var McpAgent = class McpAgent extends Agent {
constructor(..._args) {
super(..._args);
@@ -1369,18 +2071,121 @@ var McpAgent = class McpAgent extends Agent {
@@ -1369,18 +2072,121 @@ var McpAgent = class McpAgent extends Agent {
async getInitializeRequest() {
return this.ctx.storage.get("initializeRequest");
}
Expand Down Expand Up @@ -1338,7 +1324,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
/**
* Reverse lookup: find which POST stream a given `requestId` belongs
* to, and return the stream's full `requestIds` list in the same
@@ -1407,10 +2212,14 @@ var McpAgent = class McpAgent extends Agent {
@@ -1407,10 +2213,14 @@ var McpAgent = class McpAgent extends Agent {
limit: STREAM_REQS_SCAN_LIMIT
});
if (rows.size === STREAM_REQS_SCAN_LIMIT) console.warn(`McpAgent: getStreamForRequestId hit the ${STREAM_REQS_SCAN_LIMIT}-key scan cap; stale __mcp_stream_reqs__ entries may be accumulating from abandoned POSTs`);
Expand All @@ -1357,7 +1343,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
}
/** Read the transport type for this agent.
* This relies on the naming scheme being `sse:${sessionId}`,
@@ -1498,6 +2307,12 @@ var McpAgent = class McpAgent extends Agent {
@@ -1498,6 +2308,12 @@ var McpAgent = class McpAgent extends Agent {
}
/** Sets up the MCP transport and server every time the Agent is started.*/
async onStart(props) {
Expand All @@ -1370,7 +1356,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
if (props) await this.updateProps(props);
else this.props = await this.ctx.storage.get("props");
await this.init();
@@ -1516,23 +2331,36 @@ var McpAgent = class McpAgent extends Agent {
@@ -1516,23 +2332,36 @@ var McpAgent = class McpAgent extends Agent {
return;
}
break;
Expand Down Expand Up @@ -1422,7 +1408,7 @@ index 1edcf0c8c9e67aa211ae515e7672cdf79912101e..231220c26b995a48e40dba993773c287
}
}
}
@@ -1697,7 +2525,9 @@ var McpAgent = class McpAgent extends Agent {
@@ -1697,7 +2526,9 @@ var McpAgent = class McpAgent extends Agent {
}
};
McpAgent.STREAM_REQS_KEY_PREFIX = "__mcp_stream_reqs__:";
Expand Down
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