A heavy --tui session (browser snapshots, large tool outputs) silently
OOM-killed the Node parent within minutes — closing the gateway child's
stdin, which the user saw only as a bare "gateway exited" / stdin EOF.
CLI was immune. Root cause: each completed tool's verbose trail line
embedded up to 16KB of result_text, persisted in transcript Msg.tools[]
for the whole session and rendered EXPANDED by default, so an Ink
render-node tree was built for every one of up to 800 messages at once.
That tree blew past Node's heap at a few hundred MB — far below the 2.5GB
memory-monitor exit threshold, so the death was never even attributed.
- text.ts: persisted verbose tool-trail blocks now cap to a small preview
(VERBOSE_TRAIL_MAX_CHARS=800/12 lines), not the 16KB live-render budget.
Retained trail strings drop ~17x (12.2MB -> 0.7MB at 800 msgs); the live
streaming tail still uses the larger LIVE_RENDER budget.
- tui_gateway/server.py: lower the gateway-side verbose text cap to match
(1KB/16 lines) so we stop shipping output the TUI no longer renders.
- memoryMonitor.ts: derive critical/high thresholds from the real V8 heap
ceiling (~88%/70%) instead of the hardcoded 2.5GB that killed the process
at 31% of an 8GB ceiling; add a one-shot onWarn early-warning on fast
sub-threshold heap growth so the next such death is diagnosable, not silent.
- entry.tsx: wire onWarn to a crash-log breadcrumb + stderr line.
Full tool output is unchanged in the agent context and SQLite session — this
is display/transport only, no behavior or context change.
Fixes#34095. Related #27282.
Tests: ui-tui text + new memoryMonitor suites (33 pass), python verbose-cap
guard (5 pass); full ui-tui suite shows no new failures vs pristine main.
E2E repro confirms the retention drop.
e76d8bf5aa