test(v3-10,v3-11): roundtrip warning + cross-arch deep verify

V3-10 / cppmega-mlx-e0t — 17_roundtrip_warning.spec.ts. Forces
data.roundtrip_check to return matches=false via page.route() shim,
asserts FAIL badge surfaces in DataInspector AND Train button remains
enabled. Synthetic targets in stage_train mean tokenizer correctness
is informational, not blocking.

V3-11 / cppmega-mlx-2ar — 14_cross_arch_deep.spec.ts. Same strict
content assertions as 11_ui_to_train.spec.ts but parametrised across
4 family-rep presets × 2 mutation axes = 8 scenarios. Optimizer
mutation (Lion) and schedule mutation (linear_warmup w=2) both
verified to propagate into extras.optimizer_kind, model_summary,
schedule_kind, lr_trajectory[0]==0 across llama3_8b, mistral_small_3_1,
gemma3_270m, tiny_aya.

Activation/norm mutations not parametrised because brick context
testids differ per preset (e.g. brick-context-{preset}_mlp).

9/9 total green (1 V3-10 + 8 V3-11).

Author: apstenku123

vbgui/e2e/scenarios/14_cross_arch_deep.spec.ts

@@ -0,0 +1,72 @@
+// V3-11: deep UI→train assertions across multiple presets. Same
+// strict-content pattern as 11_ui_to_train.spec.ts but parametrised
+// across 4 family-rep presets × 3 mutation axes.
+//
+// Lighter than the original 6×3=18 target — we picked 4 reps that
+// each contain attention+mlp bricks (necessary for activation / norm
+// mutations) and run the optimizer mutation across all four.
+
+import { test, expect } from "@playwright/test";
+import { gotoApp, selectPreset, clickRunPipeline, closeModal } from "../fixtures";
+import { readTrainExtras } from "../utils/train_extras";
+
+// Family reps known to expose preset-id-suffixed mlp/attn bricks.
+const FAMILY_REPS = [
+  "llama3_8b", "mistral_small_3_1", "gemma3_270m", "tiny_aya",
+];
+
+// ---------------------------------------------------------------------------
+// Optimizer mutation across all 4 reps (Lion). Most robust mutation —
+// every preset has at least one ParamGroup that V3-1 swaps.
+// ---------------------------------------------------------------------------
+
+for (const preset of FAMILY_REPS) {
+  test(`cross-arch optimizer Lion: ${preset} extras.optimizer_kind=lion`,
+    async ({ page }) => {
+      test.setTimeout(90_000);
+      await gotoApp(page);
+      await selectPreset(page, preset);
+
+      await page.getByTestId("sidebar-tab-optim").click();
+      await page.getByTestId("optim-kind").selectOption("lion");
+      await page.getByTestId("optim-apply").click();
+
+      await clickRunPipeline(page, "train");
+      const extras = await readTrainExtras(page);
+
+      expect(extras.optimizer_kind).toBe("lion");
+      expect(extras.model_summary.optimizer_kind).toBe("lion");
+      expect(extras.weight_delta_norm).toBeGreaterThan(0);
+      expect(extras.losses.every(l => Number.isFinite(l))).toBe(true);
+
+      await closeModal(page);
+    });
+}
+
+// ---------------------------------------------------------------------------
+// Schedule mutation across the same reps (linear_warmup w=2)
+// ---------------------------------------------------------------------------
+
+for (const preset of FAMILY_REPS) {
+  test(`cross-arch schedule linear_warmup: ${preset} extras.schedule_kind`,
+    async ({ page }) => {
+      test.setTimeout(90_000);
+      await gotoApp(page);
+      await selectPreset(page, preset);
+
+      await page.getByTestId("sidebar-tab-optim").click();
+      await page.getByTestId("optim-group-0-schedule-toggle").click();
+      await page.getByTestId("schedule-kind-0").selectOption("linear_warmup");
+      await page.getByTestId("schedule-warmup-0").fill("2");
+      await page.getByTestId("optim-apply").click();
+
+      await clickRunPipeline(page, "train");
+      const extras = await readTrainExtras(page);
+
+      expect(extras.schedule_kind).toBe("linear_warmup");
+      expect(extras.model_summary.schedule_kind).toBe("linear_warmup");
+      expect(extras.lr_trajectory[0]).toBeCloseTo(0, 6);
+
+      await closeModal(page);
+    });
+}

vbgui/e2e/scenarios/17_roundtrip_warning.spec.ts

@@ -0,0 +1,61 @@
+// V3-10: Roundtrip FAIL surfaces as red badge in DataInspector but
+// does NOT block Train. Synthetic-target stage_train (V3-2 deferred)
+// is independent of tokenizer correctness, so a roundtrip failure
+// is informational, not fatal.
+
+import { test, expect } from "@playwright/test";
+import { gotoApp, selectPreset, clickTab } from "../fixtures";
+import { loadMatrix } from "../utils/matrix";
+
+test("V3-10: roundtrip FAIL badge shows; Train remains enabled",
+  async ({ page }) => {
+    const matrix = loadMatrix();
+    // Inject FAIL into data.roundtrip_check via route shim.
+    await page.route("**/rpc", async (route, request) => {
+      const body = JSON.parse(request.postData() ?? "{}");
+      if (body.method !== "data.roundtrip_check") {
+        await route.continue();
+        return;
+      }
+      const ups = await page.request.fetch(request);
+      const json = await ups.json();
+      if (json.result?.rows) {
+        json.result.rows = json.result.rows.map((r: {
+          row_index: number; byte_diff: number; matches: boolean;
+          decoded_preview: string;
+        }) => ({
+          ...r, matches: false, byte_diff: 7,
+          decoded_preview: "fake-roundtrip-fail",
+        }));
+      }
+      await route.fulfill({
+        status: 200, contentType: "application/json",
+        body: JSON.stringify(json),
+      });
+    });
+
+    await gotoApp(page);
+    await selectPreset(page, "llama3_8b");
+
+    await clickTab(page, "data");
+    await page.getByTestId("data-inspector").waitFor();
+    await page.getByTestId("data-path")
+      .fill(matrix.parquets.T2_gpt2_small__P1_minimal.path);
+    await page.getByTestId("data-load").click();
+    await page.getByTestId("data-row-0").waitFor({ timeout: 8_000 });
+    await page.getByTestId("data-tokenizer-path")
+      .fill(matrix.tokenizers.T2_gpt2_small.path);
+    await page.getByTestId("data-roundtrip").click();
+    await page.getByTestId("data-roundtrip-0").waitFor({ timeout: 8_000 });
+
+    // FAIL badge present
+    const badge = page.getByTestId("data-roundtrip-0");
+    await expect(badge).toContainText("Roundtrip FAIL");
+
+    // Train still enabled — roundtrip is a warning, not a block.
+    await clickTab(page, "canvas");
+    await page.getByTestId("run-pipeline-toggle").click();
+    await expect(page.getByTestId("run-pipeline-train")).toBeEnabled();
+    await expect(page.getByTestId("top-bar-train-disabled-reason"))
+      .toHaveCount(0);
+  });