Port of upstream grok-build 0.2.113/0.2.114 fixes, extended to Kigi's
startup order.
- kigi-tty-utils runtime module: worker-cap policy (8 max) — tokio's
per-core default pins 100+ thread slots on many-core shared hosts
against RLIMIT_NPROC / pids.max, and later spawns die with EAGAIN.
- kigi-bin builds the main runtime with capped workers and reports an
out-of-threads host with a diagnostic + exit(1) instead of a panic.
- The pre-runtime optimization threads (HTTP warmup, early model
prefetch) spawn recoverably and degrade — their panic would have
preempted the runtime's own diagnostic.
- The per-session actor thread and its runtime report spawn/build
failure through the existing acp::Error / AgentBuildError boundaries
(new RuntimeBuild variant) instead of panicking the agent host.
- fsnotify's watcher thread spawn maps into FsNotifyError::WatcherStart
so callers degrade instead of crashing.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KSy9S31pZNWXtRZNVJ1sDf
ZacharyZhang-NYandClaude Fable 5
97de661554