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bc-mcp-bridge: timeout + one-retry-with-fresh-session self-heal

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Neither fetch() call had a timeout, and the BC session (Mcp-Session-Id)
plus the underlying HTTP connection were reused for the bridge process's
entire lifetime with no proactive refresh. A long-running Claude Code
session with gaps between calls can leave either stale.

Observed today: a 30-minute hang on one call (no timeout meant it never
failed on its own), and separately an "Internal_CompanyNotFound" on two
machines that likely wasn't a real company problem but a dead session --
Michael noticed the pattern independently: Summatim's frequent quick calls
never have this issue, longer sessions with gaps do.

Added REQUEST_TIMEOUT_MS (30s) via AbortSignal.timeout on both fetch
calls, and wrapped forward() to retry once with sessionId cleared on any
failure -- self-heals a stale session/connection without the developer
noticing. Tested end to end: full initialize + tools/call succeeds
normally (no retry needed), and a forced-failure path correctly retries
once then surfaces the real error if it persists.
This commit is contained in:
Michael Dieringer 2026-08-05 14:05:42 +02:00
parent ea5ca2c3fd
commit 0563887aea
1 changed files with 34 additions and 2 deletions
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36
custom/setup/bc-mcp-bridge.js
View file

@ -15,6 +15,14 @@ const fs = require("fs");
const path = require("path");
const ENDPOINT = "https://mcp.businesscentral.dynamics.com";
// 2026-08-04: neither fetch() call below had a timeout, and the BC session
// (sessionId) + underlying HTTP connection were reused for the bridge
// process's entire lifetime with no proactive refresh. A long-running Claude
// Code session with gaps between calls can leave either stale -- observed as
// a 30-minute hang on one call, and separately as an "Internal_CompanyNotFound"
// that wasn't actually a company problem. REQUEST_TIMEOUT_MS + the one-retry
// wrapper below fail fast and self-heal with a forced-fresh session instead.
const REQUEST_TIMEOUT_MS = 30000;
function die(m) { process.stderr.write(`[bc-mcp-bridge] ${m}\n`); process.exit(1); }
@ -56,6 +64,7 @@ async function getToken() {
method: "POST",
headers: { "Content-Type": "application/x-www-form-urlencoded" },
body,
signal: AbortSignal.timeout(REQUEST_TIMEOUT_MS),
});
if (!r.ok) throw new Error(`token ${r.status}: ${await r.text()}`);
const j = await r.json();
@ -76,7 +85,7 @@ function parseSSE(text) {
return msgs;
}
async function forward(msg) {
async function forwardOnce(msg) {
const tok = await getToken();
const headers = {
"Authorization": `Bearer ${tok}`,
@ -88,7 +97,12 @@ async function forward(msg) {
"ConfigurationName": enc(cfg.config),
};
if (sessionId) headers["Mcp-Session-Id"] = sessionId;
const r = await fetch(ENDPOINT, { method: "POST", headers, body: JSON.stringify(msg) });
const r = await fetch(ENDPOINT, {
method: "POST",
headers,
body: JSON.stringify(msg),
signal: AbortSignal.timeout(REQUEST_TIMEOUT_MS),
});
const sid = r.headers.get("mcp-session-id"); if (sid) sessionId = sid;
const ct = r.headers.get("content-type") || "";
const text = await r.text();
@ -103,6 +117,24 @@ async function forward(msg) {
return ct.includes("text/event-stream") ? parseSSE(text) : (text.trim() ? [text.trim()] : []);
}
async function forward(msg) {
try {
return await forwardOnce(msg);
} catch (e) {
// 2026-08-04: one retry with a forced-fresh BC session (sessionId cleared).
// A long-idle Claude Code session can leave the cached Mcp-Session-Id or
// the underlying HTTP connection stale -- observed as a request hanging
// until REQUEST_TIMEOUT_MS, or as an "Internal_CompanyNotFound" that was
// actually a dead session, not a real company problem. Quick, frequent
// calls never idle long enough to hit this; a long session with gaps
// between calls does. One retry self-heals without the developer noticing;
// if the retry also fails, this is a real error and should surface as one.
process.stderr.write(`[bc-mcp-bridge] retrying after: ${e.message || e}\n`);
sessionId = null;
return await forwardOnce(msg);
}
}
// Splits text into chunks of max maxLen chars, breaking at word boundaries.
function splitTextToChunks(text, maxLen = 250) {
const chunks = [];