fix(scripts): make smoke:tui assert the TUI survives its first frame (#2147)

AGENTS.md

@@ -973,7 +973,13 @@ The ⚠️ option-deletion hazard, the snapshot rule, and the recovery recipe ab
 - `smoke:web:elicit` (`scripts/smoke-web-elicitation.mjs`, #1854) is the app-rendered **elicitation** counterpart of `smoke:web:app`: same prod `--web` server and the same deep-link connect, but it then calls `app_choose_option` from the Tools tab, waits for `[data-testid="app-elicitation"][data-app-elicitation-status="ready"]`, clicks a choice **inside the sandboxed app** (two `frameLocator` hops — the trusted sandbox proxy, then the untrusted app), and asserts the app's standard `ElicitResult` comes back in the *tool result*, i.e. that it reached the server rather than merely the host. It then repeats against `app-elicitation-native-http.json` — the same tool and app on a server that never advertised the nested MCP Apps `elicitation` capability — and asserts the **native** elicitation dialog takes it and no app modal is rendered. That second half is the more valuable one: the failure this feature can produce is not "the app doesn't render" but "an app renders when it should not have been offered one", which strands every user of a server that never opted in. Set `SMOKE_SCREENSHOT_DIR` to capture PNGs of the three states (used for PR proof); unset, it asserts only. Two mechanics worth knowing: the main-view tabs are a Mantine `SegmentedControl`, so there is no `role="tab"` — the clickable element is the sibling `label[for$="-Tools"]`; and the prompt string also appears in the (hidden) Protocol-tab payload, so the fallback assertion is scoped to the dialog rather than a bare text lookup.
 
 - **The build gate for the browser-externalized-builtin class (#1769)** is the earlier, more complete companion to `smoke:web:browser`. A Vite plugin in `clients/web/vite.config.ts` (logic in `clients/web/server/browser-externalized-builtin-gate.ts`, unit-tested) turns Vite 8's _browser-externalization warning_ (`Module "node:*" has been externalized for browser compatibility`) into a hard `vite build` error, so a Node built-in in the browser graph now **fails `npm run build` / `validate`** instead of shipping a `{}` stub. This catches **both** the _called-at-init_ case (which `smoke:web:browser` also catches, but later/at runtime) **and** the _imported-but-never-called_ case (the `{}` stub that is invisible to the runtime smoke "by design" — see above). Because rolldown **swallows a throw inside `onLog`** (the one hook where a thrown error doesn't abort — verified against vite@8.0.0), the plugin _records_ the warning in `onLog` and re-throws in `buildEnd`. There is **no stable log `code`**, so the gate keys off the documented message phrasing; `npm run verify:build-gate` (`scripts/verify-build-gate.mjs`, in `npm run ci` and the GitHub workflow) runs a real build with a `node:fs` probe forced into `src/main.tsx` and asserts the build fails via the gate — the only check that catches the message phrasing **drifting** in a future Vite bump and silently disabling the gate. The gate is scoped to `vite build` (`apply: 'build'`) — never `vite dev` or the vitest projects — **and** to the browser (`client`) environment (`applyToEnvironment`), so a future SSR/node environment built from this config isn't failed for a legitimate `node:*` import; the Node runner build (tsup, `build:runner`) is a separate config where built-ins are legitimate. `smoke:web:browser` stays as the runtime backstop for crashes the build can't reason about.
-- `smoke:cli` (`scripts/smoke-cli.mjs`) drives `mcp-inspector --cli` through the built launcher against the bundled stdio test server via a temp `--catalog`: it asserts `tools/list` returns the server's tools (real connect over stdio), the default writable catalog is seeded empty on first run, a missing read-only `--config` errors without seeding, and `--catalog` + `--config` is rejected. `smoke:tui` (`scripts/smoke-tui.mjs`) launches `mcp-inspector --tui --catalog <temp>` and asserts the Ink app renders its first frame (the "MCP Servers" panel) within a timeout, then SIGTERMs it — a shallow boot/render check, not full interaction. **`smoke:tui` is local-only: it self-skips when `process.env.CI` is set**, because the Ink TUI needs a real TTY (raw mode) that headless CI lacks — so run it (via `npm run smoke`) on your own machine before pushing. Both build `test-servers/build` on demand if it's missing.
+- `smoke:cli` (`scripts/smoke-cli.mjs`) drives `mcp-inspector --cli` through the built launcher against the bundled stdio test server via a temp `--catalog`: it asserts `tools/list` returns the server's tools (real connect over stdio), the default writable catalog is seeded empty on first run, a missing read-only `--config` errors without seeding, and `--catalog` + `--config` is rejected. `smoke:tui` (`scripts/smoke-tui.mjs`) launches `mcp-inspector --tui --catalog <temp>` **under a pseudoterminal**, asserts the Ink app renders its first frame (the "MCP Servers" panel) within a timeout, then waits `SMOKE_TUI_SURVIVE_MS` (default 2s) and asserts it is **still running** before SIGTERMing it — a shallow boot/render/survival check, not full interaction. Both build `test-servers/build` on demand if it's missing.
+
+  **The survival half is the assertion, and it is the whole point (#2147).** This smoke used to settle OK the instant the marker appeared and never look at the child again. It was spawning the TUI with `stdio: ["ignore", …]`, i.e. stdin on `/dev/null`; Ink mounts `useInput`, `useInput` needs raw mode, and raw mode is a property of the **file descriptor** — so the TUI painted one frame and died ~40ms later with `Raw mode is not supported on the current process.stdin`. The smoke won that ~40ms race and printed OK. What it asserted was *first paint*, while its own header claimed "boots and renders without crashing", and it had never once verified a running TUI **on any machine** — `stdio: ["ignore", …]` makes the child's stdin `/dev/null` whether or not the developer's own terminal is a TTY. The race also cut both ways: an `exit` processed first failed the run, which reads as flake rather than as the standing defect it was.
+
+  Two pieces, and the order matters. **`scripts/lib/pty.mjs`** gives the child a real terminal via `script(1)` — no dependency, and the flavors are not interchangeable (BSD takes argv, util-linux takes one shell string plus `-e`, busybox that string without `-e`), so the invocation is built and unit-tested rather than written inline; a platform with no `script(1)` (Windows) **skips** rather than running without one, since that is a guaranteed failure and not a weaker check. **`scripts/lib/render-smoke.mjs`** is the fix: it requires the child to outlive its first frame. Without that, a future harness change reintroduces the same false green and nothing notices — which is why it lives in a module `test:scripts` drives against a stub that paints the marker and immediately exits (the old harness passes that stub; this one must not), rather than in a smoke that only ever walks its own happy path. Do **not** collapse the survival wait back into "resolve on the marker" to save two seconds.
+
+  **`smoke:tui` is still local-only: it self-skips when `process.env.CI` is set** — now by decision rather than by capability. The PTY removes the technical blocker the skip used to cite; whether it joins GitHub CI is a separate call, and #2146 deliberately keeps the other local-only smokes out. So run it (via `npm run smoke`) on your own machine before pushing: a local-only gate is exactly where a false green is least likely to be caught by anything else.
 - Storybook play-function tests (`clients/web` `test:storybook`) run in headless Chromium via `@vitest/browser-playwright` (~10s). They are part of `npm run ci` (which installs Playwright chromium first); kept out of `validate` because they need the browser binary and are slower than the unit suite.
 
 ### The web smokes are engine-parameterized; Firefox is in the pre-push gate, not CI (#2086)