Two targeted fixes on the critical path from `hermes --tui` launch to
`gateway.ready`:
1. **Defer `@hermes/ink` import in memoryMonitor.ts.** The static top-level
import dragged the full ~414KB Ink bundle (React + renderer + all
components/hooks) onto the critical path *before* `gw.start()` could
spawn the Python gateway — serialising ~155ms of Node work in front of
it on every launch. `evictInkCaches` only runs inside the 10-second
tick under heap pressure, so it moves to a lazy dynamic import. First
tick hits the ESM cache because the app entry has long since imported
`@hermes/ink`.
2. **Gate `tools.mcp_tool` import on config in tui_gateway/entry.py.**
Importing the module transitively pulls the MCP SDK + pydantic + httpx
+ jsonschema + starlette formparsers (~200ms). The overwhelming
majority of users have no `mcp_servers` configured, so this runs for
nothing. A cheap `load_config()` check (~25ms) skips the 200ms import
when no servers are declared, with a conservative fallback to the old
behaviour if the config probe itself fails.
## Measurements (macOS Terminal.app, Apple Silicon, n=12)
| Metric | Before (p50) | After (p50) | Δ |
|----------------------------|--------------|-------------|----------|
| Python gateway boot alone | 252–365ms | 105–151ms | −180ms |
| `hermes --tui` banner paint | 686ms | 665ms | −21ms |
| `hermes --tui` → ready | **1843ms** | **1655ms** | **−188ms (−10.2%)** |
| `hermes --tui` → ready p90 | 1932ms | 1778ms | −154ms |
| stdev (ready) | 126ms | 83ms | also more consistent |
## Tests
- `scripts/run_tests.sh tests/tui_gateway/ tests/tools/test_mcp_tool.py`:
195 passed. (The one pre-existing failure in
`test_session_resume_returns_hydrated_messages` reproduces on main —
unrelated, it's a mock-DB kwarg mismatch.)
- `ui-tui` vitest: 430 tests, all pass.
- `npm run type-check` in ui-tui: clean.
## Notes
- Node-side first paint ("banner") didn't move meaningfully because that
latency is dominated by Ink's render pipeline + React mount, not by
which imports load first.
- The win shows up entirely in the time from banner to `gateway.ready`
— exactly where we expected it, since both fixes shorten the Python
gateway's boot path or let it overlap more with Node startup.
- No user-visible behaviour change. Memory monitoring still fires every
10s; MCP still works when `mcp_servers` is configured.
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