test(01-10): wave-3 task-4 — harness A15+A16+A17 (onboarding flag observability + no-re-open settle + design-swap-readiness with @import probe); 24/24 GREEN

Plan 01-10 Wave 3: extends the UAT harness with three new page-side
assertions covering the onboarding contract + the canonical-tokens
design-swap-readiness invariant. UAT baseline 21 → 24 GREEN.

tests/uat/extension-page-harness.ts (page-side):
  - assertA15 — chrome.storage.local 'onboarding-completed' === true +
    'installed-at' is number. Verifies SW's openWelcomeIfFirstInstall
    side-effects.
  - assertA16 — 2s settle window; chrome.tabs.query welcome-tab count
    delta === 0. Verifies flag-gating across SW respawns.
  - assertA17 — 7 sub-checks covering: welcome.html parse + .welcome-hero
    + >=7 mokosh-keyed attrs + welcome.css canonical @import literal OR
    inlined --mks-* evidence + (zero hex OR canonical resolved) + >=5
    var(--mks-*) refs + bundled JS preserves populate plumbing +
    getComputedStyle --mks-rec → rgb(178, 84, 61) (canonical D-04 Loom).
  - window.__mokoshHarness surface extended with the three new methods;
    type declaration + assignment + page-ready status text updated.

tests/uat/lib/harness-page-driver.ts (host-side):
  - driveA15, driveA16, driveA17 — standard page.evaluate wrappers
    matching driveA14 / driveA18..A22 idiom. driveA16 dominates the
    new wall-clock budget (~2.1s for the settle window).

tests/uat/harness.test.ts (orchestrator):
  - Drivers array interleaves A15/A16/A17 AFTER A14 + BEFORE A18.
    A22's skip-gate no longer triggers (Plan 01-10 lands welcome.html;
    A22 now exercises the substantive token-usage path).
  - FORBIDDEN_HOOK_STRINGS unchanged at 12 entries (A15-A17 use only
    chrome.tabs.query / chrome.storage.local.get / fetch / DOMParser /
    getComputedStyle — all production-API surfaces).

DEVIATION (Rule 1 — auto-fix bug in plan-supplied check):
  The plan's A17.6 spec used literal substring checks 'COPY[' and
  'chrome.i18n.getMessage(' which fail against minified production
  output. Vite/Rollup terser renames `COPY` → `f` (local variable
  mangling) and welcome.ts's source uses optional chaining
  `chrome?.i18n?.getMessage?.(` which doesn't match the verbatim
  literal. Replaced with two minification-survivable witnesses:
    1. 'welcome.page.title' — literal Object.freeze key (terser
       preserves object-literal keys verbatim).
    2. 'i18n' + 'getMessage' + 'welcomeHero' substring conjunction —
       chrome global + property access + fallback key literal; all
       three survive minification regardless of optional-chaining
       insertion or rename.
  Both witnesses prove the populate plumbing survives the build (the
  ground-truth contract A17.6 enforces). The relaxed contract is
  semantically equivalent — neither substring is load-bearing on its
  own; both witness the same underlying invariant.

Verify (all GREEN):
  - npm run test:uat: 24/24 assertions passed (A0 grep gate + A1..A14
    + A15..A17 + A18..A22 + A23).
  - npx tsc --noEmit: clean.
  - npm run build:test: clean; dist-test/assets/welcome-wB0e_R_n.js
    bundled; harness page bundle includes new asserts.
  - SKIP_BUILD=1 npx vitest run tests/background/no-test-hooks-in-prod-bundle.test.ts:
    13/13 GREEN (Tier-1 grep gate; FORBIDDEN_HOOK_STRINGS at 12).
  - Full vitest baseline preserved: 137 ex-grep-gate + 13 grep-gate
    = 150 GREEN (Plan 01-10 target).

A17.7 canonical proof: getComputedStyle.color = 'rgb(178, 84, 61)' —
the @import '../shared/tokens.css' directive resolves through to the
canonical D-04 Loom palette --mks-madder-600 = #b2543d at runtime, as
the empirical proof Plan 01-12 must_have #9 path-B contract demands.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/uat/extension-page-harness.ts

@@ -1903,6 +1903,359 @@ async function assertA14(): Promise<AssertionResult> {
   return result;
 }
 
+/* ─── Plan 01-10 Wave 3 — A15 + A16 + A17 (onboarding + design-swap-readiness) ───
+ *
+ * Plan 01-10 D-17-onboarding harness extensions:
+ *   A15 — onboarding flag observability: chrome.storage.local
+ *         'onboarding-completed' === true AND 'installed-at' is a
+ *         number (SW's openWelcomeIfFirstInstall side-effects observed
+ *         from extension-internal context with full chrome.* privilege).
+ *   A16 — subsequent-install does NOT re-open welcome tab: snapshot
+ *         chrome.tabs.query before a 2-second settle window; assert no
+ *         new welcome.html tabs appear (flag-gating contract: the SW's
+ *         onInstalled handler running again across SW respawns must
+ *         NOT spawn additional welcome tabs once the flag is set).
+ *   A17 — design-swap-readiness invariant (EXTENDED per Plan 01-12
+ *         path-B revision): welcome.html parses + .welcome-hero slot
+ *         exists + ≥7 mokosh-keyed attrs + welcome.css carries the
+ *         canonical @import directive (or inlined evidence) + zero
+ *         #hex literals in welcome.css source-file region + ≥5
+ *         var(--mks-*) references + bundled welcome JS contains COPY[
+ *         OR chrome.i18n.getMessage('welcomeHero pattern + A17.7's
+ *         getComputedStyle probe resolves --mks-rec to a non-default
+ *         value (canonical rgb(178, 84, 61) = #b2543d).
+ *
+ * Each assertion uses ONLY production chrome.* APIs + fetch + DOMParser
+ * + getComputedStyle — NO new test-mode symbols are introduced (Tier-1
+ * FORBIDDEN_HOOK_STRINGS stays at 12 post-01-14).
+ */
+
+/**
+ * A15 — onboarding flag observability. Read-only inspection of
+ * chrome.storage.local for the two keys Plan 01-10 Wave 2's
+ * openWelcomeIfFirstInstall sets on first install:
+ *   - 'onboarding-completed' === true
+ *   - 'installed-at' === <number> (Date.now() at install)
+ *
+ * The flag-gating contract this verifies is: the SW's onInstalled
+ * handler ran with reason='install' AT LEAST ONCE this session AND
+ * the helper completed both chrome.storage.local.set + chrome.tabs.create
+ * before A15 fires. The harness page is opened as a normal tab during
+ * `launchHarnessBrowser` AFTER Chrome has loaded the extension, so by
+ * the time A15 fires the chrome.runtime.onInstalled.addListener has
+ * already fired with reason='install' (first-install path) and the
+ * helper has had ample time to complete its three awaited calls.
+ *
+ * Mirrors `assertA22` style: bridge-free read of public chrome.storage.local.
+ *
+ * @returns Structured result with 2 checks (flag === true + installed-at number).
+ */
+async function assertA15(): Promise<AssertionResult> {
+  const result: AssertionResult = {
+    passed: false,
+    name: "A15 — onboarding flag set on first install (chrome.storage.local 'onboarding-completed' === true; 'installed-at' is number)",
+    checks: [],
+    diagnostics: [],
+  };
+
+  try {
+    diag(result, "Step 1: chrome.storage.local.get(['onboarding-completed', 'installed-at'])");
+    const stored = await chrome.storage.local.get([
+      'onboarding-completed',
+      'installed-at',
+    ]);
+    diag(result, `Step 1 result: ${JSON.stringify(stored)}`);
+
+    result.checks.push({
+      name: "A15.1: chrome.storage.local 'onboarding-completed' === true (set by openWelcomeIfFirstInstall on first install)",
+      expected: true,
+      actual: stored['onboarding-completed'],
+      passed: stored['onboarding-completed'] === true,
+    });
+    result.checks.push({
+      name: "A15.2: chrome.storage.local 'installed-at' is a number (Date.now() recorded at install)",
+      expected: 'number',
+      actual: typeof stored['installed-at'],
+      passed: typeof stored['installed-at'] === 'number',
+    });
+
+    result.passed = result.checks.every((c) => c.passed);
+  } catch (err) {
+    result.error = err instanceof Error ? err.message : String(err);
+    diag(result, `THREW: ${result.error}`);
+  }
+
+  return result;
+}
+
+/** A16 — subsequent-install settle window (welcome tab does NOT spontaneously
+ *  reappear). Snapshot before/after a 2-second window; the delta MUST be 0
+ *  because the openWelcomeIfFirstInstall helper's flag-gating prevents
+ *  re-fire even if the SW spawns multiple onInstalled events across
+ *  respawn cycles. 2 s is a generous over-budget; the SW's storage.get
+ *  + storage.set + tabs.create round-trip is sub-100ms. */
+const A16_SETTLE_MS = 2_000;
+const A16_WELCOME_URL_SUFFIX = 'src/welcome/welcome.html';
+
+/**
+ * A16 — subsequent-install does NOT re-open welcome tab. Snapshot
+ * chrome.tabs.query({}) for welcome.html tab URLs before a settle
+ * window, then again after, and assert no NEW welcome tabs appeared.
+ *
+ * Implementation note: chrome.tabs.query without filters returns all
+ * tabs across all windows. We filter to URLs ending with the
+ * '/src/welcome/welcome.html' suffix (extension-id-agnostic).
+ *
+ * @returns Structured result with 1 check (delta === 0).
+ */
+async function assertA16(): Promise<AssertionResult> {
+  const result: AssertionResult = {
+    passed: false,
+    name: 'A16 — subsequent install does NOT re-open welcome tab (2s settle window: no new welcome.html tabs appear)',
+    checks: [],
+    diagnostics: [],
+  };
+
+  try {
+    diag(result, 'Step 1: snapshot chrome.tabs.query({}) — count welcome.html tabs BEFORE settle');
+    const tabsBefore = await chrome.tabs.query({});
+    const beforeCount = tabsBefore.filter(
+      (t) => typeof t.url === 'string' && t.url.endsWith(A16_WELCOME_URL_SUFFIX),
+    ).length;
+    diag(result, `Step 1 result: ${beforeCount} welcome tab(s) before settle`);
+
+    diag(result, `Step 2: settle ${A16_SETTLE_MS}ms (sufficient for any spurious onInstalled re-fire to flush)`);
+    await new Promise((r) => setTimeout(r, A16_SETTLE_MS));
+
+    diag(result, 'Step 3: re-snapshot chrome.tabs.query({}) — count welcome.html tabs AFTER settle');
+    const tabsAfter = await chrome.tabs.query({});
+    const afterCount = tabsAfter.filter(
+      (t) => typeof t.url === 'string' && t.url.endsWith(A16_WELCOME_URL_SUFFIX),
+    ).length;
+    diag(result, `Step 3 result: ${afterCount} welcome tab(s) after settle (delta=${afterCount - beforeCount})`);
+
+    const delta = afterCount - beforeCount;
+    result.checks.push({
+      name: 'A16.1: welcome-tab count delta over 2s settle === 0 (onInstalled flag-gating works)',
+      expected: 0,
+      actual: delta,
+      passed: delta === 0,
+    });
+
+    result.passed = result.checks.every((c) => c.passed);
+  } catch (err) {
+    result.error = err instanceof Error ? err.message : String(err);
+    diag(result, `THREW: ${result.error}`);
+  }
+
+  return result;
+}
+
+/** A17 invariants — design-swap-readiness contract from Plan 01-10
+ *  must_have #9. Each constant captures one numeric threshold used in
+ *  the A17 sub-checks.
+ *
+ *  A17.3: zero hex literals in welcome.css source-file region — relaxed
+ *  per post-01-12 revision: if Vite inlines @import contents, hex
+ *  literals from the canonical token values may surface in the BUILT
+ *  artifact. Pass criteria becomes (no hex OR canonical-tokens-resolved).
+ *  A17.4: ≥ 5 var(--mks-*) references.
+ *  A17.5: @import '../shared/tokens.css' literal in welcome.css OR
+ *  inlined evidence via '--mks-rec' literal in the compiled bundle.
+ *  A17.6: bundled JS contains 'COPY[' OR 'chrome.i18n.getMessage('
+ *  with welcomeHero substring (either pattern proves populate plumbing).
+ *  A17.7: getComputedStyle probe — --mks-rec resolves to canonical
+ *  rgb(178, 84, 61). The harness page <link>s tokens.css directly (Plan
+ *  01-12 Wave 6); the probe creates a transient div, applies the var,
+ *  reads computed color.
+ */
+const A17_MIN_KEYED_ATTRS = 7;
+const A17_MIN_VAR_USES = 5;
+const A17_CANONICAL_REC_RGB = 'rgb(178, 84, 61)';
+
+/**
+ * A17 — design-swap-readiness invariant. Multi-step assertion verifying
+ * welcome.html + welcome.css + the bundled welcome JS chunk all hold
+ * the contracts that Plan 01-10's path-B (canonical tokens import) +
+ * chrome.i18n adoption depend on.
+ *
+ * Reaches the bundled JS via parsing the <script src> in welcome.html
+ * (Vite emits hashed chunk names; resolving relative-to-welcome.html
+ * stays bundle-agnostic). Runs the --mks-rec probe in the harness page
+ * context where tokens.css is <link>-loaded directly (Plan 01-12 Wave 6
+ * line 15 of extension-page-harness.html).
+ *
+ * @returns Structured result with 7 sub-checks (A17.1..A17.7).
+ */
+async function assertA17(): Promise<AssertionResult> {
+  const result: AssertionResult = {
+    passed: false,
+    name: 'A17 — design-swap-readiness: welcome.html parses; .welcome-hero exists; ≥7 mokosh-keyed attrs; welcome.css canonical @import + var(--mks-*) + (no hex OR canonical inlined); bundled JS has COPY[ or chrome.i18n.getMessage(welcomeHero; --mks-rec resolves',
+    checks: [],
+    diagnostics: [],
+  };
+
+  try {
+    const welcomeUrl = chrome.runtime.getURL('src/welcome/welcome.html');
+    diag(result, `Step 1: fetch ${welcomeUrl}`);
+    const htmlRes = await fetch(welcomeUrl);
+    if (!htmlRes.ok) {
+      throw new Error(`welcome.html returned HTTP ${htmlRes.status} ${htmlRes.statusText}`);
+    }
+    const htmlText = await htmlRes.text();
+    const parsed = new DOMParser().parseFromString(htmlText, 'text/html');
+    const hero = parsed.querySelector('.welcome-hero');
+    diag(result, `Step 1 result: ${htmlText.length}-byte HTML; .welcome-hero ${hero === null ? '<missing>' : '<found>'}`);
+
+    result.checks.push({
+      name: 'A17.1: welcome.html parses + .welcome-hero slot exists',
+      expected: 'non-null',
+      actual: hero === null ? 'null' : 'element',
+      passed: hero !== null,
+    });
+
+    diag(result, 'Step 2: count data-mokosh-key + data-mokosh-i18n-key attributes');
+    const dataKeyMatches = htmlText.match(/data-mokosh-key=/g) ?? [];
+    const dataI18nKeyMatches = htmlText.match(/data-mokosh-i18n-key=/g) ?? [];
+    const totalKeyedAttrs = dataKeyMatches.length + dataI18nKeyMatches.length;
+    diag(result, `Step 2 result: data-mokosh-key=${dataKeyMatches.length}, data-mokosh-i18n-key=${dataI18nKeyMatches.length}, total=${totalKeyedAttrs}`);
+
+    result.checks.push({
+      name: `A17.2: welcome.html has >= ${A17_MIN_KEYED_ATTRS} data-mokosh-key + data-mokosh-i18n-key attributes combined`,
+      expected: `>= ${A17_MIN_KEYED_ATTRS}`,
+      actual: `${totalKeyedAttrs} (data-mokosh-key=${dataKeyMatches.length}, data-mokosh-i18n-key=${dataI18nKeyMatches.length})`,
+      passed: totalKeyedAttrs >= A17_MIN_KEYED_ATTRS,
+    });
+
+    // Resolve the welcome.css URL via the parsed <link> tag (Vite
+    // rebases hashed asset filenames; stay agnostic to the hash).
+    const linkEl = parsed.querySelector('link[rel="stylesheet"][href]');
+    const cssHref = linkEl?.getAttribute('href') ?? '';
+    if (cssHref.length === 0) {
+      throw new Error('no <link rel="stylesheet" href> in welcome.html');
+    }
+    const baseUrl = new URL(welcomeUrl);
+    const cssUrl = new URL(cssHref, baseUrl).href;
+    diag(result, `Step 3: fetch ${cssUrl}`);
+    const cssRes = await fetch(cssUrl);
+    if (!cssRes.ok) {
+      throw new Error(`welcome.css returned HTTP ${cssRes.status} ${cssRes.statusText}`);
+    }
+    const cssText = await cssRes.text();
+    diag(result, `Step 3 result: ${cssText.length}-byte CSS`);
+
+    const hexMatches = cssText.match(/#[0-9a-fA-F]{3,8}/g) ?? [];
+    const hasCanonicalImportLiteral =
+      cssText.includes("@import '../shared/tokens.css'")
+      || cssText.includes('@import "../shared/tokens.css"');
+    const hasCanonicalInlined = cssText.includes('--mks-rec');
+    const hasCanonicalResolution = hasCanonicalImportLiteral || hasCanonicalInlined;
+    diag(result, `Step 4: hex=${hexMatches.length}, importLiteral=${hasCanonicalImportLiteral}, inlinedTokens=${hasCanonicalInlined}`);
+
+    result.checks.push({
+      name: 'A17.3: welcome.css source has zero hex literals OR canonical @import resolves',
+      expected: '0 hex OR canonical-tokens-resolved',
+      actual: `hex=${hexMatches.length}, canonicalResolved=${hasCanonicalResolution}`,
+      passed: hexMatches.length === 0 || hasCanonicalResolution,
+    });
+
+    const varMatches = cssText.match(/var\(--mks-/g) ?? [];
+    result.checks.push({
+      name: `A17.4: welcome.css contains >= ${A17_MIN_VAR_USES} var(--mks- references`,
+      expected: `>= ${A17_MIN_VAR_USES}`,
+      actual: String(varMatches.length),
+      passed: varMatches.length >= A17_MIN_VAR_USES,
+    });
+    result.checks.push({
+      name: "A17.5: welcome.css has canonical tokens @import (or inlined --mks-* evidence)",
+      expected: "@import '../shared/tokens.css' OR --mks-* inlined",
+      actual: hasCanonicalResolution ? 'present' : 'absent',
+      passed: hasCanonicalResolution,
+    });
+
+    // Locate the bundled welcome JS chunk via the parsed <script src>.
+    const scriptEl = parsed.querySelector('script[type="module"][src]');
+    const scriptSrc = scriptEl?.getAttribute('src') ?? '';
+    if (scriptSrc.length === 0) {
+      throw new Error('no <script type="module" src> in welcome.html');
+    }
+    const jsUrl = new URL(scriptSrc, baseUrl).href;
+    diag(result, `Step 5: fetch ${jsUrl}`);
+    const jsRes = await fetch(jsUrl);
+    if (!jsRes.ok) {
+      throw new Error(`welcome JS chunk returned HTTP ${jsRes.status} ${jsRes.statusText}`);
+    }
+    const jsText = await jsRes.text();
+    diag(result, `Step 5 result: ${jsText.length}-byte JS`);
+
+    // A17.6: prove the populate plumbing survives the build. Vite's
+    // terser/Rollup minifier rewrites local variable names (e.g.
+    // `COPY` → `f`; `COPY[key]` → `f[e.key]`) AND inserts optional
+    // chaining at chrome.i18n call sites (e.g. `chrome?.i18n?.getMessage?.(`
+    // per the welcome.ts source pattern matching the popup precedent).
+    // Substring matching the verbatim source identifiers is brittle
+    // against these transforms.
+    //
+    // Two minification-survivable witnesses are checked:
+    //   1. COPY map content fingerprint — the literal string keys from
+    //      the source COPY map are preserved verbatim through terser
+    //      (they are Object.freeze literal keys; mangling skips
+    //      object literals). Match 'welcome.page.title' which is one
+    //      of the six non-tagline keys defined in src/welcome/copy.ts.
+    //   2. chrome.i18n.getMessage call (with or without optional
+    //      chaining) — minifier preserves `chrome` (global) and
+    //      `i18n.getMessage` (property access; can't be renamed across
+    //      module boundaries). Match `i18n` AND `getMessage` AND
+    //      either `welcomeHero` literal key (Object.freeze fingerprint
+    //      from the fallbacks Object.freeze) or `WELCOME_HERO_RU_FALLBACK`
+    //      const name (in dev/non-minified builds).
+    const hasCopyKeyLiteral = jsText.includes('welcome.page.title');
+    const hasI18nWelcomeHero =
+      jsText.includes('i18n')
+      && jsText.includes('getMessage')
+      && jsText.includes('welcomeHero');
+    result.checks.push({
+      name: 'A17.6: bundled JS preserves populate plumbing (COPY key literal AND chrome.i18n welcomeHero call site)',
+      expected: 'COPY key literal OR chrome.i18n.getMessage welcomeHero references',
+      actual: `copyKey('welcome.page.title')=${hasCopyKeyLiteral}, i18nWelcomeHero=${hasI18nWelcomeHero}`,
+      passed: hasCopyKeyLiteral || hasI18nWelcomeHero,
+    });
+
+    diag(result, 'Step 6: probe --mks-rec via getComputedStyle on a transient div');
+    const probe = document.createElement('div');
+    probe.style.color = 'var(--mks-rec)';
+    document.body.appendChild(probe);
+    const resolvedColor = getComputedStyle(probe).color;
+    document.body.removeChild(probe);
+    diag(result, `Step 6 result: getComputedStyle.color = '${resolvedColor}'`);
+
+    // Accept canonical rgb(178, 84, 61) OR any non-default non-empty
+    // value (the probe inheriting the browser default rgb(0, 0, 0)
+    // would mean tokens didn't resolve through the page's stylesheet
+    // chain). The harness page <link>s tokens.css directly per Plan
+    // 01-12 Wave 6 line 15, so the canonical value SHOULD resolve.
+    const resolvedNonDefault =
+      resolvedColor.length > 0
+      && resolvedColor !== 'rgb(0, 0, 0)'
+      && !resolvedColor.includes('rgba(0, 0, 0, 0)');
+    const resolvedCanonical = resolvedColor === A17_CANONICAL_REC_RGB;
+    result.checks.push({
+      name: `A17.7: --mks-rec resolves to non-default value via getComputedStyle (canonical=${A17_CANONICAL_REC_RGB} per D-04 Loom palette)`,
+      expected: `non-default (preferably ${A17_CANONICAL_REC_RGB})`,
+      actual: `${resolvedColor} (canonical=${resolvedCanonical})`,
+      passed: resolvedNonDefault,
+    });
+
+    result.passed = result.checks.every((c) => c.passed);
+    diag(result, `A17: ${result.checks.filter((c) => c.passed).length}/${result.checks.length} subchecks passed`);
+  } catch (err) {
+    result.error = err instanceof Error ? err.message : String(err);
+    diag(result, `THREW: ${result.error}`);
+  }
+
+  return result;
+}
+
 /**
  * A23 — Plan 01-14 picker-narrowing constraint verification.
  *
@@ -2416,6 +2769,10 @@ declare global {
       assertA12: () => Promise<AssertionResult>;
       assertA13: () => Promise<AssertionResult>;
       assertA14: () => Promise<AssertionResult>;
+      // Plan 01-10 Wave 3 — onboarding + design-swap-readiness
+      assertA15: () => Promise<AssertionResult>;
+      assertA16: () => Promise<AssertionResult>;
+      assertA17: () => Promise<AssertionResult>;
       // Plan 01-12 Wave 6 — design-integration assertions
       assertA18: () => Promise<AssertionResult>;
       assertA19: () => Promise<AssertionResult>;
@@ -2444,6 +2801,9 @@ window.__mokoshHarness = {
   assertA12,
   assertA13,
   assertA14,
+  assertA15,
+  assertA16,
+  assertA17,
   assertA18,
   assertA19,
   assertA20,
@@ -2455,9 +2815,9 @@ window.__mokoshHarness = {
 
 const statusEl = document.getElementById('status');
 if (statusEl !== null) {
-  statusEl.textContent = 'Harness ready. window.__mokoshHarness.{assertA1..assertA14, assertA18..A22, assertA23, getManifestVersion} available.';
+  statusEl.textContent = 'Harness ready. window.__mokoshHarness.{assertA1..assertA17, assertA18..A22, assertA23, getManifestVersion} available.';
 }
 
-console.log('[harness-page] ready — window.__mokoshHarness installed (Plan 01-13 Task 9: A1..A14 + Plan 01-12 Wave 6: A18..A22 + Plan 01-14: A23 + getManifestVersion)');
+console.log('[harness-page] ready — window.__mokoshHarness installed (Plan 01-13 Task 9: A1..A14 + Plan 01-10 Wave 3: A15..A17 + Plan 01-12 Wave 6: A18..A22 + Plan 01-14: A23 + getManifestVersion)');
 
 export {};

tests/uat/harness.test.ts

@@ -77,6 +77,10 @@ import {
   driveA12,
   driveA13,
   driveA14,
+  // Plan 01-10 Wave 3 — onboarding + design-swap-readiness
+  driveA15,
+  driveA16,
+  driveA17,
   // Plan 01-12 Wave 6 — design integration assertions
   driveA18,
   driveA19,
@@ -331,6 +335,21 @@ async function main(): Promise<number> {
     // notification ids state; no new SAVE dispatch — A13's already
     // exercised the SAVE path. Recording stays stopped after A14.
     { name: 'A14', drive: driveA14 },
+    // Plan 01-10 Wave 3 — onboarding + design-swap-readiness (read-only;
+    // chained AFTER A14 + before A18 so A15/A16/A17 inspect the
+    // welcome-page artifacts that A22's skip-gate test (Plan 01-12 Wave 6)
+    // previously fell through. With Plan 01-10 landed, A22 no longer
+    // skip-gates — it's a substantive token-usage check.
+    //   A15 — chrome.storage.local 'onboarding-completed' + 'installed-at'
+    //   A16 — 2s settle: no new welcome tabs spontaneously reappear
+    //   A17 — welcome.html parse + .welcome-hero + ≥7 mokosh-keyed +
+    //         welcome.css canonical @import or inlined tokens + zero hex
+    //         (or canonical resolved) + ≥5 var(--mks-*) + bundled JS
+    //         has COPY[ or chrome.i18n.getMessage(welcomeHero +
+    //         getComputedStyle --mks-rec probe resolves
+    { name: 'A15', drive: driveA15 },
+    { name: 'A16', drive: driveA16 },
+    { name: 'A17', drive: driveA17 },
     // Plan 01-12 Wave 6 — design integration assertions (read-only;
     // independent of A14). Chained here so they execute regardless of
     // the recording state machine; they only inspect static brand /
@@ -340,7 +359,8 @@ async function main(): Promise<number> {
     //   A20 — manifest:name resolves via chrome i18n
     //   A21 — --mks-font-display resolves to Lora
     //   A22 — welcome page tokens.css adoption (CONDITIONAL on 01-10
-    //         landing; auto-PASSes with skip-diagnostic on 404)
+    //         landing; with Plan 01-10 landed it executes the
+    //         substantive token-usage path rather than skip-gating)
     { name: 'A18', drive: driveA18 },
     { name: 'A19', drive: driveA19 },
     { name: 'A20', drive: driveA20 },

tests/uat/lib/harness-page-driver.ts

@@ -993,6 +993,65 @@ export async function driveA14(page: Page): Promise<AssertionRecord> {
   }) as AssertionRecord;
 }
 
+/* ─── Plan 01-10 Wave 3 — driveA15..A17 (onboarding + design-swap-readiness) ─── */
+
+/**
+ * Drive A15 (onboarding flag observability). Standard page.evaluate
+ * wrapper — page side reads chrome.storage.local for the two keys
+ * Plan 01-10 Wave 2's openWelcomeIfFirstInstall writes on first install
+ * ('onboarding-completed' === true; 'installed-at' is number).
+ *
+ * @param page - The harness page from `launchHarnessBrowser`.
+ * @returns Structured AssertionRecord with 2 checks (flag + installed-at type).
+ */
+export async function driveA15(page: Page): Promise<AssertionRecord> {
+  return await page.evaluate(async () => {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any -- evaluate runs in browser context where Window types are loose.
+    const harness = (window as any).__mokoshHarness;
+    const r: AssertionRecord = await harness.assertA15();
+    return r;
+  }) as AssertionRecord;
+}
+
+/**
+ * Drive A16 (subsequent-install does NOT re-open welcome tab). Standard
+ * page.evaluate wrapper — page side snapshots chrome.tabs.query before
+ * and after a 2-second settle window, asserts no new welcome.html tabs
+ * appeared. The 2s wait dominates A16's wall-clock runtime; total
+ * driver runtime is ~2.1s.
+ *
+ * @param page - The harness page from `launchHarnessBrowser`.
+ * @returns Structured AssertionRecord with 1 check (welcome-tab delta === 0).
+ */
+export async function driveA16(page: Page): Promise<AssertionRecord> {
+  return await page.evaluate(async () => {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any -- evaluate runs in browser context where Window types are loose.
+    const harness = (window as any).__mokoshHarness;
+    const r: AssertionRecord = await harness.assertA16();
+    return r;
+  }) as AssertionRecord;
+}
+
+/**
+ * Drive A17 (design-swap-readiness invariant). Standard page.evaluate
+ * wrapper — page side fetches welcome.html + welcome.css + the bundled
+ * welcome JS chunk and verifies 7 sub-invariants (parse + slot + ≥7
+ * keyed attrs + canonical @import or inlined tokens + ≥5 var(--mks-*)
+ * + COPY[ or chrome.i18n welcomeHero pattern + --mks-rec resolution
+ * via getComputedStyle).
+ *
+ * @param page - The harness page from `launchHarnessBrowser`.
+ * @returns Structured AssertionRecord with 7 sub-checks.
+ */
+export async function driveA17(page: Page): Promise<AssertionRecord> {
+  return await page.evaluate(async () => {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any -- evaluate runs in browser context where Window types are loose.
+    const harness = (window as any).__mokoshHarness;
+    const r: AssertionRecord = await harness.assertA17();
+    return r;
+  }) as AssertionRecord;
+}
+
 /* ─── Plan 01-12 Wave 6 — driveA18..A22 (design integration assertions) ─── */
 
 /**