ASSESSMENT: the idle-session cause was OpenCode 1.15 waiting on a piped stdin

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ASSESSMENT.md

@@ -188,9 +188,13 @@ Ornith's time was lost mostly to the owner's tests and task text. By category:
 - **The OpenCode sandbox** refuses anything outside the repository, including `/tmp` and the nix
   store. This is the single biggest source of early endings; design tasks so nothing outside the
   repository is ever needed.
-- **OpenCode upgrades** ran a one-time database migration on the next start. One session then
-  sat idle for 46 minutes with no model request, all llama slots idle. A trivial prompt worked
-  afterwards. The driver had no timeout, so nothing noticed.
+- **OpenCode 1.15 hangs as a background job unless stdin is closed.** After an upgrade (it ran a
+  one-time database migration), `opencode run` started reading a piped stdin as extra prompt
+  and waiting for EOF. A backgrounded driver's stdin never closes, so two resume sessions sat
+  idle for 46 and 10 minutes without sending one model request (all llama slots idle), while
+  the same command in the foreground worked. Confirmed side by side: exit 124 without, `pong`
+  with `</dev/null`. Both `run-plan.sh` scripts now pass `</dev/null`. The driver had no timeout,
+  so nothing noticed.
 
 ## 8. Recommendations