The real cause of the long-task "Lost connection to the AI provider" — the
earlier 300s-timeout fix (#176) was the wrong layer. The provider-HTTP telemetry
on the user's deploy shows the failures are PRE-RESPONSE `read ECONNRESET` ~500ms
in (not a 300s/15min timeout), correlated with idleSincePrevCall ~42s and large
bodies; and crucially a retry of the SAME request often succeeds. A direct probe
to the real z.ai endpoint does NOT reset (113KB bodies and a 45s-idle keep-alive
reuse both succeed), and another agent (opencode) runs fine from the same infra —
so the provider is healthy and the egress network is usable. The difference is
the transport: undici's keep-alive pool REUSES a socket that the deployment's
egress (NAT / firewall / conntrack) silently dropped during a long idle gap, so
the next request resets pre-response.
Fix (brings gitmost in line with clients that don't reuse stale sockets):
- Keep-alive recycling: the streaming dispatcher (chat fetch AND the external-MCP
dispatcher, via the shared streamingDispatcherOptions) now sets
keepAliveTimeout + keepAliveMaxTimeout to a 10s recycle window
(AI_STREAM_KEEPALIVE_MS), so a connection idle longer than that is closed
instead of reused — a long-gap step opens a fresh connection. keepAliveMaxTimeout
also caps a server-advertised keep-alive so the provider can't widen the window.
- Pre-response connection retry: createStreamingFetch retries a connection-level
reset (ECONNRESET / UND_ERR_SOCKET / ECONNREFUSED / EPIPE / *_TIMEOUT) on a
fresh connection up to 2 times. This is SAFE because fetch() only rejects before
the Response resolves — a started stream is never replayed; an abort (client
disconnect) is never retried.
Tests: ai-streaming-fetch.spec — keep-alive options, streamKeepAliveMs env,
isRetryableConnectError, and a server that resets the first connection so the
retry must land on a fresh one (+ aborted requests are not retried). Verified on
the stand that a normal turn still streams (reasoning + text + finish) through the
new transport. server tsc + ai/mcp specs green.
Note: root cause is the deployment's egress dropping idle connections (Traefik is
inbound-only); this makes the app resilient to it. AI_STREAM_KEEPALIVE_MS can be
lowered if the egress drops faster than ~10s.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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