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fix(mcp): parse SSE-framed responses from mcp-org streamable-HTTP #49

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Merged
JustAGhosT merged 1 commit into from
May 18, 2026
Merged

fix(mcp): parse SSE-framed responses from mcp-org streamable-HTTP #49

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26 changes: 25 additions & 1 deletion backend/src/mcp/orgClient.ts
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
import { config } from '../config.js';

type OrgToolResult = { content: { type: string; text: string }[]; isError?: boolean };
type Envelope = { result?: OrgToolResult; error?: { message: string } };

let _requestId = 1;

Expand Down Expand Up @@ -38,7 +39,19 @@ export async function callOrgTool(
};
}

const envelope = await res.json() as { result?: OrgToolResult; error?: { message: string } };
const contentType = res.headers.get('content-type') ?? '';
const rawText = await res.text();
let envelope: Envelope;
try {
envelope = contentType.includes('text/event-stream')
? parseSseEnvelope(rawText)
: JSON.parse(rawText);
} catch (err) {
return {
content: [{ type: 'text', text: `Failed to parse mcp-org response (${contentType}): ${String(err)} — body: ${rawText.slice(0, 200)}` }],
isError: true,
};
}
if (envelope.error) {
return { content: [{ type: 'text', text: `mcp-org error: ${envelope.error.message}` }], isError: true };
}
Expand All @@ -47,3 +60,14 @@ export async function callOrgTool(
return { content: [{ type: 'text', text: `Failed to reach mcp-org: ${String(err)}` }], isError: true };
}
}

function parseSseEnvelope(text: string): Envelope {
for (const frame of text.split(/\r?\n\r?\n/)) {
const dataLines: string[] = [];
for (const line of frame.split(/\r?\n/)) {
if (line.startsWith('data:')) dataLines.push(line.slice(5).trimStart());
}
if (dataLines.length > 0) return JSON.parse(dataLines.join('\n')) as Envelope;

@chatgpt-codex-connector chatgpt-codex-connector Bot May 18, 2026

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P1 Badge Continue scanning SSE frames until JSON-RPC result appears

parseSseEnvelope returns after parsing the first SSE frame that has any data: lines, but Streamable HTTP responses are allowed to include JSON-RPC notifications/requests before the actual response. In that case this code will either throw on non-JSON data or parse a non-response message and cause callOrgTool to return empty response, even though a valid result frame appears later in the same stream. The parser should keep iterating frames until it finds a JSON-RPC message with a matching response shape (or exhausts the stream).

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}
throw new Error('no data lines in SSE response');
}
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