host found this while we were elsewhere: four agent-sidecar crashes tonight, one
truncating the owner's turn mid-sentence.
error: ProcessTransport is not ready for writing
at write (…/claude-agent-sdk/sdk.mjs) <- no frames from our code
A floating rejection inside the SDK's own input pump, so no await of ours could
have caught it. With no handler anywhere in src/servers it reached the top
level, Bun exited, PM2 restarted, and every live session on the machine died —
not just the one whose transport failed.
That is 975673a for the second time. It fixed the one path someone had thought
of, a Postgres query throwing, and its own message named the consequence: "any
Postgres restart killed every live agent session on the machine". The general
case had no backstop.
Now logged loudly and survived. This does not pretend an unhandled rejection is
fine — it makes it debuggable instead of fatal.
uncaughtException is deliberately not handled the same way: a rejection leaves
the process's state intact, a synchronous throw that unwound to the top may not
have, and continuing on a corrupted heap is worse than restarting. Same blast
radius either way, which argues for durable sessions rather than for surviving
anything at any cost.
The trigger is untouched and unconfirmed — most likely the CLI exiting while
streamInput is still pumping. That needs catching in the act on the live host.
Also worth knowing, since d59adbf interacts: this restart sweep runs several
times an hour on that machine, and a session with no recorded userId is now
skipped rather than asked about, so it stays marked generating until a
reconnect. A stuck "generating" spinner after an agent restart is that, not the
UI.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
