diff --git a/.github/workflows/verify.yml b/.github/workflows/verify.yml
new file mode 100644
index 00000000..b3109896
--- /dev/null
+++ b/.github/workflows/verify.yml
@@ -0,0 +1,40 @@
+# Cross-adapter capture-parity gate (Layer A). Runs the committed golden
+# fixtures through the reader and snapshots them — fast, no browser. Fixture
+# regeneration (`pnpm fixtures:regen`) needs a real browser and is a deliberate
+# maintainer/nightly step, not part of this gate.
+name: Verify
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      - name: Use Node.js
+        uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6.2.0
+        with:
+          node-version-file: .nvmrc
+      - name: Cache pnpm modules
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
+        env:
+          cache-name: cache-pnpm-modules
+        with:
+          path: ~/.pnpm-store
+          key: ${{ runner.os }}-verify-${{ env.cache-name }}-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-verify-${{ env.cache-name }}-
+      - uses: pnpm/action-setup@41ff72655975bd51cab0327fa583b6e92b6d3061 # v4.2.0
+        with:
+          version: 10.26.1
+          run_install: false
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+      - name: 🔍 Lint harness
+        run: pnpm exec eslint test
+      - name: 🧪 Cross-adapter capture parity
+        run: pnpm verify
diff --git a/CLAUDE.md b/CLAUDE.md
index 71bd7d1f..89268c0f 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -248,6 +248,7 @@ Documented divergences from the conventions above. They exist today as debt to b
 - Nightwatch native asserts are buffered at call time and emitted in one batch at test-end (Nightwatch exposes no per-assertion execution/outcome hook reachable from the plugin — `client.queue.tree` / `client.reporter` aren't on `browser`). Streaming mid-run would flash every assert green before its outcome is known, so rows are held and reconciled against `results.testcases[*].assertions` at `afterEach` (the flat `results.assertions` only reflects the last testcase). The exporter re-sorts commands by timestamp (`buildActionEvents`) so the batched rows land at their real timeline positions rather than clustering at flush time. `actual` is parsed from the failure message (`but got: …`, failures only) into a collapsed `{passed, expected, actual}` result; `expected` is the assertion arg — the label still mirrors the call args, not the derived values.
 - Nightwatch's BDD `describe/it` interface fires the plugin's global `beforeEach`/`afterEach` **once per module** (with an empty `currentTest.name`), not per `it` — Nightwatch runs the individual `it`s internally with no per-testcase hook or event reachable from the plugin (the lib emits only transport-level events). So `traceGranularity:'test'` records a single slice boundary (the first test) and collapses to one session-scoped slice; retry-aware/per-test retention (`tracePolicy`) degrades to session scope for this interface. Per-test slicing works for adapters/styles that expose per-test hooks (WDIO mocha/cucumber, Selenium mocha; likely Nightwatch's exports-object style, unverified). Session-granularity trace is unaffected. **No per-test support has been built for this interface** — real per-`it` slicing needs a hook Nightwatch doesn't surface; deferred to a full-picture pass, not attempted yet.
   - **Empirically confirmed** (BDD example, `mode:'trace'` + `traceGranularity:'test'` + `tracePolicy:'retain-on-failure'` + `screenshot:'on'` + `video:'retain-on-failure'`): the one collapsed slice is keyed to the **first** test's uid (the artifacts manifest's `tests[]` still carries every testcase with correct `state`, so metadata capture is fine — it's the *slice/artifact* keying that collapses). Consequence: with a passing first test and a failing later test, the screenshot **produces** (policy `'on'` captures regardless of outcome, keyed to the first test) but the **trace zip and video are dropped** — `retain-on-failure` evaluates the first (passing) test's outcome, and the actually-failing test never gets its own slice to retain. The per-test produce-only path itself (screenshot/video write + manifest) is correct; only the BDD slice-keying limits it.
+- **Nightwatch cucumber: no `trace.zip` is written in trace mode** (surfaced by the `test/` verification harness, 2026-07-27). Root cause is hook ordering, not granularity: the plugin's cucumber `After` hook runs at `order: -1` (deliberately *after* Nightwatch's browser-quit hook, so it can read final assertion status — see `helpers/cucumberHooks.cts`). By the time `finalizeCucumberScenario` runs its capture/`flushTestSlice`, the per-scenario browser session is already torn down, so `#flushSpecTrace`/`#writeTraceIfNeeded` bail on the absent `sessionCapturer.metadata?.sessionId` and nothing is written — under **either** `traceGranularity`. (`'session'` also has no single live session at run-end because cucumber uses one session per scenario.) Per-scenario metadata capture and **live mode are unaffected**; only the trace-mode zip export is missing. A proper fix must capture/write each scenario's trace **before the browser quits** (e.g. from the last `AfterStep` or a pre-quit hook), which needs a rework + browser-iterated verification. A runnable example exists at `examples/nightwatch/cucumber/` (live-capable); the harness keeps the `nightwatch-cucumber` entry `planned` until this lands.
 - Service renders expect-webdriverio matchers as single `expect.<matcher>` rows by **folding**, not stack/depth suppression (the old `#assertionDepth`/`#matcherStarted`/self-heal machinery is gone). The matcher's value-read (`toHaveText`→`getText`, `toExist`→`isExisting`, …) is captured as a normal command; `afterAssertion` then coalesces the synthesized `expect.*` row into that read in place — inheriting its callSource, screenshot, and timeline position — and the fold replaces **by timestamp, never a public `id`**: `id` is the per-worker `commandCounter`, which resets per spec, so stamping one lets the app's id-first `replaceCommand` swap a same-id row from another spec (duplicate rows + a fold from another spec vanishing, in multi-spec live mode). `beforeAssertion` arms the pending matcher (depth-counted so aliases like `toBeChecked`→`toBeSelected` fold once); a matcher that **hard-throws** — element never resolves, so expect-webdriverio's `waitUntil` rethrows and `afterAssertion` never fires — is synthesized at `afterTest`/`afterStep` from the throwing read, so a failing assertion renders as `expect.<matcher>` whether or not the element existed. Two limits: its error is then the read's (`Can't call getText on … element wasn't found`), not an assertion-phrased message; and `MATCHER_READ_COMMANDS` is a hand-maintained allowlist, so a matcher whose read isn't listed leaves its raw read visible alongside the `expect.*` row. Plain-value jest matchers (`expect(x).toBe(y)`) don't fire the ewdio hooks, so they aren't captured as rows.
 
 ### File-size (raw line counts; soft cap is 500 logic lines)
diff --git a/examples/nightwatch/cucumber/features/login.feature b/examples/nightwatch/cucumber/features/login.feature
new file mode 100644
index 00000000..05fdd88d
--- /dev/null
+++ b/examples/nightwatch/cucumber/features/login.feature
@@ -0,0 +1,15 @@
+Feature: Example site smoke test
+
+  Mirrors the Nightwatch BDD smoke-test: open a site, wait for the body to be
+  visible, and assert the page title. Runs as a Cucumber scenario so the
+  cross-adapter harness has a nightwatch-cucumber trace fixture.
+
+  Scenario Outline: I can open a site and read its title
+    Given I navigate to "<url>"
+    When the page body becomes visible
+    Then the page title contains "<title>"
+
+    Examples:
+      | url                    | title   |
+      | https://example.com    | Example |
+      | https://example.org    | Example |
diff --git a/examples/nightwatch/cucumber/features/step_definitions/login.steps.js b/examples/nightwatch/cucumber/features/step_definitions/login.steps.js
new file mode 100644
index 00000000..00e11202
--- /dev/null
+++ b/examples/nightwatch/cucumber/features/step_definitions/login.steps.js
@@ -0,0 +1,18 @@
+// Step definitions for the example-site smoke scenario.
+//
+// Nightwatch's Cucumber integration injects the Nightwatch `browser` onto the
+// World, so steps reach it via `this.browser` — hence regular (non-arrow)
+// functions so `this` binds to the World.
+const { Given, When, Then } = require('@cucumber/cucumber')
+
+Given(/^I navigate to "([^"]*)"$/, async function (url) {
+  await this.browser.url(url)
+})
+
+When(/^the page body becomes visible$/, async function () {
+  await this.browser.waitForElementVisible('body', 5000)
+})
+
+Then(/^the page title contains "([^"]*)"$/, async function (title) {
+  await this.browser.assert.titleContains(title)
+})
diff --git a/examples/nightwatch/cucumber/nightwatch.cucumber.conf.cjs b/examples/nightwatch/cucumber/nightwatch.cucumber.conf.cjs
new file mode 100644
index 00000000..52318614
--- /dev/null
+++ b/examples/nightwatch/cucumber/nightwatch.cucumber.conf.cjs
@@ -0,0 +1,69 @@
+// Simple import - just require the package
+const path = require('node:path')
+const nightwatchDevtools = require('@wdio/nightwatch-devtools').default
+const { cucumberHooksPath } = require('@wdio/nightwatch-devtools')
+
+const featuresDir = path.resolve(__dirname, 'features')
+
+module.exports = {
+  // Resolve relative to this config file so the paths hold regardless of CWD.
+  src_folders: [path.resolve(featuresDir, 'step_definitions')],
+  output_folder: false, // Skip generating nightwatch reports for this example
+  custom_commands_path: [],
+  custom_assertions_path: [],
+
+  test_runner: {
+    type: 'cucumber',
+    options: {
+      feature_path: featuresDir,
+      // Registers the DevTools Before/After/Step scenario hooks so the plugin
+      // sees each scenario as a test unit.
+      require: [cucumberHooksPath]
+    }
+  },
+
+  webdriver: {
+    start_process: true,
+    // server_path: '/opt/homebrew/bin/chromedriver',
+    port: 9515
+  },
+
+  test_settings: {
+    default: {
+      // Ensure all tests run even if one fails
+      skip_testcases_on_fail: false,
+
+      desiredCapabilities: {
+        browserName: 'chrome',
+        // Required for chromedriver to expose the BiDi WebSocket channel.
+        // Without this, attachBidiHandlers silently fails and the perf-log
+        // fallback takes over.
+        webSocketUrl: true,
+        'goog:chromeOptions': {
+          args: [
+            '--headless',
+            '--no-sandbox',
+            '--disable-dev-shm-usage',
+            '--window-size=1600,900'
+          ]
+        },
+        'goog:loggingPrefs': { performance: 'ALL' }
+      },
+      // bidi: opt-in WebDriver BiDi capture for console + network. When
+      // attached, the per-command Chrome perf-log network path is gated off to
+      // avoid duplicate entries.
+      globals: nightwatchDevtools({
+        port: 3000,
+        // Cucumber exposes per-scenario hooks, so each scenario is captured as
+        // its own test unit. Trace when the harness sets DEVTOOLS_MODE=trace,
+        // otherwise stream live to the backend/UI. NOTE: trace mode does not yet
+        // emit a zip here — the cucumber After hook runs after the browser
+        // session is torn down, so there's no live session to capture/write
+        // from. See CLAUDE.md known debt. Live mode works.
+        mode: process.env.DEVTOOLS_MODE === 'trace' ? 'trace' : 'live',
+        traceGranularity: 'session',
+        bidi: true
+      })
+    }
+  }
+}
diff --git a/examples/selenium/cucumber-test/features/support/setup.js b/examples/selenium/cucumber-test/features/support/setup.js
index 18f1e762..907dfb90 100644
--- a/examples/selenium/cucumber-test/features/support/setup.js
+++ b/examples/selenium/cucumber-test/features/support/setup.js
@@ -6,7 +6,10 @@
 
 import { DevTools } from '@wdio/selenium-devtools'
 
+// mode defaults to 'live' (the demo default); the verification harness sets
+// DEVTOOLS_MODE=trace to produce a golden fixture from this same example.
 DevTools.configure({
+  mode: process.env.DEVTOOLS_MODE === 'trace' ? 'trace' : 'live',
   screencast: { enabled: true, quality: 70, maxWidth: 1280, maxHeight: 720 },
   headless: true
 })
diff --git a/examples/wdio/mocha/wdio.trace.conf.ts b/examples/wdio/mocha/wdio.trace.conf.ts
new file mode 100644
index 00000000..3c39e5ea
--- /dev/null
+++ b/examples/wdio/mocha/wdio.trace.conf.ts
@@ -0,0 +1,53 @@
+import type { Options } from '@wdio/types'
+
+// Trace-mode variant of wdio.conf.ts, used by the verification harness
+// (`pnpm fixtures:regen`) to produce a deterministic golden trace.zip. Same
+// capabilities and specs as the live config; session granularity writes one zip
+// per run. Kept separate so the demo config's live default stays untouched.
+export const config: Options.Testrunner = {
+  runner: 'local',
+  autoCompileOpts: {
+    autoCompile: true,
+    tsNodeOpts: {
+      project: './tsconfig.json',
+      transpileOnly: true
+    }
+  },
+  specs: ['./specs/**/*.e2e.ts'],
+  exclude: [],
+  maxInstances: 1,
+  capabilities: [
+    {
+      browserName: 'chrome',
+      'goog:chromeOptions': {
+        args: [
+          '--headless',
+          '--disable-gpu',
+          '--remote-allow-origins=*',
+          '--window-size=1600,900'
+        ]
+      }
+    }
+  ],
+  logLevel: 'warn',
+  bail: 0,
+  baseUrl: 'http://localhost',
+  waitforTimeout: 10000,
+  connectionRetryTimeout: 120000,
+  connectionRetryCount: 3,
+  services: [
+    [
+      'devtools',
+      {
+        mode: 'trace' as const,
+        traceGranularity: 'session' as const
+      }
+    ]
+  ],
+  framework: 'mocha',
+  reporters: ['spec'],
+  mochaOpts: {
+    ui: 'bdd',
+    timeout: 60000
+  }
+}
diff --git a/package.json b/package.json
index a2d08b44..08e39f88 100644
--- a/package.json
+++ b/package.json
@@ -19,6 +19,11 @@
     "test:coverage": "vitest run --coverage",
     "test:ui": "vitest --ui",
     "test:debug": "node --inspect-brk ./node_modules/.bin/vitest run",
+    "verify": "vitest run --config test/vitest.config.ts",
+    "verify:watch": "vitest --config test/vitest.config.ts",
+    "verify:update": "vitest run --config test/vitest.config.ts -u",
+    "verify:ui": "wdio run test/visual/wdio.conf.ts",
+    "fixtures:regen": "tsx test/regen.ts",
     "lint": "pnpm --parallel lint",
     "watch": "pnpm build --watch",
     "changeset:gen": "bash .changeset/changeset-gen.sh"
@@ -43,6 +48,7 @@
     "@vitest/browser": "^4.1.8",
     "@vitest/coverage-v8": "^4.1.8",
     "@wdio/allure-reporter": "^9.29.1",
+    "@wdio/visual-service": "^10.1.0",
     "autoprefixer": "^10.5.0",
     "eslint": "^10.4.1",
     "eslint-config-prettier": "^10.1.8",
diff --git a/packages/nightwatch-devtools/package.json b/packages/nightwatch-devtools/package.json
index 1830cb38..f4ba6a8c 100644
--- a/packages/nightwatch-devtools/package.json
+++ b/packages/nightwatch-devtools/package.json
@@ -35,6 +35,7 @@
     "lint": "eslint .",
     "example": "nightwatch -c ../../examples/nightwatch/nightwatch.conf.cjs",
     "example:retry": "nightwatch -c ../../examples/nightwatch/nightwatch.conf.cjs --retries 1",
+    "example:cucumber": "nightwatch -c ../../examples/nightwatch/cucumber/nightwatch.cucumber.conf.cjs",
     "prepublishOnly": "pnpm build"
   },
   "keywords": [
@@ -59,6 +60,7 @@
     "yazl": "^2.5.1"
   },
   "devDependencies": {
+    "@cucumber/cucumber": "^13.0.0",
     "@types/node": "25.9.3",
     "@types/ws": "^8.18.1",
     "@wdio/devtools-core": "workspace:^",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index bff88351..c9f908e1 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -15,7 +15,7 @@ importers:
     dependencies:
       '@wdio/cli':
         specifier: 9.28.0
-        version: 9.28.0(@types/node@25.9.3)(expect-webdriverio@5.6.8)(puppeteer-core@21.11.0)
+        version: 9.28.0(@types/node@25.9.3)(expect-webdriverio@5.7.0)(puppeteer-core@21.11.0)
     devDependencies:
       '@changesets/cli':
         specifier: ^2.31.0
@@ -44,6 +44,9 @@ importers:
       '@wdio/allure-reporter':
         specifier: ^9.29.1
         version: 9.29.1
+      '@wdio/visual-service':
+        specifier: ^10.1.0
+        version: 10.1.0(webdriverio@9.28.0(puppeteer-core@21.11.0))
       autoprefixer:
         specifier: ^10.5.0
         version: 10.5.0(postcss@8.5.15)
@@ -264,7 +267,7 @@ importers:
         version: 11.2.0
       '@wdio/cli':
         specifier: 9.28.0
-        version: 9.28.0(@types/node@25.9.3)(expect-webdriverio@5.6.8)(puppeteer-core@21.11.0)
+        version: 9.28.0(@types/node@25.9.3)(expect-webdriverio@5.7.0)(puppeteer-core@21.11.0)
       '@wdio/devtools-app':
         specifier: workspace:^
         version: link:../app
@@ -362,7 +365,7 @@ importers:
         version: link:../core
       '@wdio/globals':
         specifier: 9.28.0
-        version: 9.28.0(expect-webdriverio@5.6.8)(webdriverio@9.28.0(puppeteer-core@21.11.0))
+        version: 9.28.0(expect-webdriverio@5.7.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))
       tsup:
         specifier: ^8.5.1
         version: 8.5.1(@microsoft/api-extractor@7.58.9(@types/node@25.9.3))(jiti@2.7.0)(postcss@8.5.15)(tsx@4.22.4)(typescript@6.0.3)(yaml@2.9.0)
@@ -371,7 +374,7 @@ importers:
         version: 6.0.3
       vitest:
         specifier: ^4.0.16
-        version: 4.1.9(@types/node@25.9.3)(@vitest/coverage-v8@4.1.9)(happy-dom@20.10.4)(jsdom@24.1.3)(vite@8.0.16(@types/node@25.9.3)(esbuild@0.28.0)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0))
+        version: 4.1.9(@types/node@25.9.3)(@vitest/coverage-v8@4.1.9)(happy-dom@20.10.4)(jsdom@24.1.3)(vite@8.0.16(@types/node@25.9.3)(esbuild@0.27.7)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0))
 
   packages/nightwatch-devtools:
     dependencies:
@@ -412,6 +415,9 @@ importers:
         specifier: ^2.5.1
         version: 2.5.1
     devDependencies:
+      '@cucumber/cucumber':
+        specifier: ^13.0.0
+        version: 13.0.0
       '@types/node':
         specifier: 25.9.3
         version: 25.9.3
@@ -622,7 +628,7 @@ importers:
         version: link:../shared
       '@wdio/globals':
         specifier: 9.28.0
-        version: 9.28.0(expect-webdriverio@5.6.8)(webdriverio@9.28.0(puppeteer-core@21.11.0))
+        version: 9.28.0(expect-webdriverio@5.7.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))
       '@wdio/protocols':
         specifier: 9.28.0
         version: 9.28.0
@@ -2755,6 +2761,16 @@ packages:
       expect-webdriverio: ^5.6.5
       webdriverio: ^9.0.0
 
+  '@wdio/globals@9.29.1':
+    resolution: {integrity: sha512-F96BKppx4HGD64v+s57TM4K4zaxqUCg2RXHk6sjB2xrSa7P+d2VYV28ID2ddF7iSodVfPlpa1i2/jy8jMGrU8w==}
+    engines: {node: '>=18.20.0'}
+    peerDependencies:
+      expect-webdriverio: ^5.6.5
+      webdriverio: ^9.0.0
+
+  '@wdio/image-comparison-core@2.1.0':
+    resolution: {integrity: sha512-o9w80bkMmgbUuPKoJYbuf2sKh/xyrfVyITftmVJuIaqIPehwriwGF7ZU7sS9JiXAdoqM17Wdy7MdpO3mOgsjZA==}
+
   '@wdio/local-runner@9.28.0':
     resolution: {integrity: sha512-cuITB31LRvEuOfhVNtkqBC0LQsQQTp7jumV8l7YJgchdmNI2gwyRaeKR35HxPpR8Awi5QeBfSkFxipwP8JQIWg==}
     engines: {node: '>=18.20.0'}
@@ -2824,6 +2840,9 @@ packages:
     resolution: {integrity: sha512-VDqUaXpR8oOZSs26dy06Y2LhmA8bldsXDHeZ36n8SfW+Bq0miG0RRxou7aqx7sifVbbsuxrbBPXvmK+40uAIbQ==}
     engines: {node: '>=18.20.0'}
 
+  '@wdio/visual-service@10.1.0':
+    resolution: {integrity: sha512-GsWItEpETBRy5Ymuh8HOEX1pMDME2hxSgUBW4UlSHCmKTSOcUEfQosjAx3XVMucpR5SosPIiOB1/4teEi4qLhw==}
+
   '@wdio/xvfb@9.28.0':
     resolution: {integrity: sha512-9NUB6rYS7uOzE+attbvX7frfvXdf/FhinHBL2hJtBW81/lcSm3TPqgFskKVKiUooXfdTf4bvrRYn1+MVVGFFXA==}
     engines: {node: '>=18'}
@@ -4161,6 +4180,14 @@ packages:
       '@wdio/logger': ^9.0.0
       webdriverio: ^9.0.0
 
+  expect-webdriverio@5.7.0:
+    resolution: {integrity: sha512-jLOTrJoPBC3Wtd83ryHMbRcEajMGtAnn6OWtSnoJoDLt16nHvxVdjcI4Bc0n+1KAOr8DvQtlJ55f0M48kJtEpw==}
+    engines: {node: '>=20'}
+    peerDependencies:
+      '@wdio/globals': ^9.0.0
+      '@wdio/logger': ^9.0.0
+      webdriverio: ^9.0.0
+
   expect@30.4.1:
     resolution: {integrity: sha512-PMARsyh/JtqC20HoGqlFcIlQAyqUtW4PlI1rup1uhYJtKuwAjbvWi3GQMAn+STdHum/dk8xrKfUM1+5SAwpolA==}
     engines: {node: ^18.14.0 || ^20.0.0 || ^22.0.0 || >=24.0.0}
@@ -4204,6 +4231,9 @@ packages:
   fast-levenshtein@2.0.6:
     resolution: {integrity: sha512-DCXu6Ifhqcks7TZKY3Hxp3y6qphY5SJZmrWMDrKcERSOXWQdMhU9Ig/PYrzyw/ul9jOIyh0N4M0tbC5hodg8dw==}
 
+  fast-png@8.0.0:
+    resolution: {integrity: sha512-gCysNasJ8KEMgfdYIKd/wTDo6ENK1PWT0RJO7O+0pgmuHPw2O6tA1WvdxFRJoLf9V8yFYpG0FA1YgI8X97OhJA==}
+
   fast-querystring@1.1.2:
     resolution: {integrity: sha512-g6KuKWmFXc0fID8WWH0jit4g0AGBoJhCkJMb1RmbsSEUNvQ+ZC8D6CUZ+GtF8nMzSPXnhiePyyqqipzNNEnHjg==}
 
@@ -4749,6 +4779,9 @@ packages:
     resolution: {integrity: sha512-4gd7VpWNQNB4UKKCFFVcp1AVv+FMOgs9NKzjHKusc8jTMhd5eL1NqQqOpE0KzMds804/yHlglp3uxgluOqAPLw==}
     engines: {node: '>= 0.4'}
 
+  iobuffer@6.0.1:
+    resolution: {integrity: sha512-SZWYkWNfjIXIBYSDpXDYIgshqtbOPsi4lviawAEceR1Kqk+sHDlcQjWrzNQsii80AyBY0q5c8HCTNjqo74ul+Q==}
+
   ip-address@10.2.0:
     resolution: {integrity: sha512-/+S6j4E9AHvW9SWMSEY9Xfy66O5PWvVEJ08O0y5JGyEKQpojb0K0GKpz/v5HJ/G0vi3D2sjGK78119oXZeE0qA==}
     engines: {node: '>= 12'}
@@ -6016,6 +6049,10 @@ packages:
   piscina@4.9.2:
     resolution: {integrity: sha512-Fq0FERJWFEUpB4eSY59wSNwXD4RYqR+nR/WiEVcZW8IWfVBxJJafcgTEZDQo8k3w0sUarJ8RyVbbUF4GQ2LGbQ==}
 
+  pixelmatch@7.2.0:
+    resolution: {integrity: sha512-xhcb4yHu9sM/G7foGzoLtXYcC0zHEaOXXjRKhGup0fw78Nf2Tkiapv4EQyMzrbcmQPsllAI7DbFY2UT7PlI9Pg==}
+    hasBin: true
+
   pkg-dir@4.2.0:
     resolution: {integrity: sha512-HRDzbaKjC+AOWVXxAU/x54COGeIv9eb+6CkDSQoNTt4XyWoIJvuPsXizxu/Fr23EiekbtZwmh1IcIG/l/a10GQ==}
     engines: {node: '>=8'}
@@ -7669,7 +7706,7 @@ snapshots:
       '@babel/types': 7.29.7
       '@jridgewell/remapping': 2.3.5
       convert-source-map: 2.0.0
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       gensync: 1.0.0-beta.2
       json5: 2.2.3
       semver: 6.3.1
@@ -7828,7 +7865,7 @@ snapshots:
       '@babel/parser': 7.29.7
       '@babel/template': 7.29.7
       '@babel/types': 7.29.7
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
     transitivePeerDependencies:
       - supports-color
 
@@ -8509,7 +8546,7 @@ snapshots:
   '@eslint/config-array@0.23.5':
     dependencies:
       '@eslint/object-schema': 3.0.5
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       minimatch: 10.2.5
     transitivePeerDependencies:
       - supports-color
@@ -9193,7 +9230,7 @@ snapshots:
 
   '@puppeteer/browsers@2.13.2':
     dependencies:
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       extract-zip: 2.0.1
       progress: 2.0.3
       proxy-agent: 6.5.0
@@ -9611,7 +9648,7 @@ snapshots:
       '@typescript-eslint/types': 8.61.1
       '@typescript-eslint/typescript-estree': 8.61.1(typescript@6.0.3)
       '@typescript-eslint/visitor-keys': 8.61.1
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       eslint: 10.5.0(jiti@2.7.0)
       typescript: 6.0.3
     transitivePeerDependencies:
@@ -9621,7 +9658,7 @@ snapshots:
     dependencies:
       '@typescript-eslint/tsconfig-utils': 8.61.1(typescript@6.0.3)
       '@typescript-eslint/types': 8.61.1
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       typescript: 6.0.3
     transitivePeerDependencies:
       - supports-color
@@ -9640,7 +9677,7 @@ snapshots:
       '@typescript-eslint/types': 8.61.1
       '@typescript-eslint/typescript-estree': 8.61.1(typescript@6.0.3)
       '@typescript-eslint/utils': 8.61.1(eslint@10.5.0(jiti@2.7.0))(typescript@6.0.3)
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       eslint: 10.5.0(jiti@2.7.0)
       ts-api-utils: 2.5.0(typescript@6.0.3)
       typescript: 6.0.3
@@ -9655,7 +9692,7 @@ snapshots:
       '@typescript-eslint/tsconfig-utils': 8.61.1(typescript@6.0.3)
       '@typescript-eslint/types': 8.61.1
       '@typescript-eslint/visitor-keys': 8.61.1
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       minimatch: 10.2.5
       semver: 7.8.4
       tinyglobby: 0.2.17
@@ -9794,6 +9831,14 @@ snapshots:
       chai: 6.2.2
       tinyrainbow: 3.1.0
 
+  '@vitest/mocker@4.1.9(vite@8.0.16(@types/node@25.9.3)(esbuild@0.27.7)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0))':
+    dependencies:
+      '@vitest/spy': 4.1.9
+      estree-walker: 3.0.3
+      magic-string: 0.30.21
+    optionalDependencies:
+      vite: 8.0.16(@types/node@25.9.3)(esbuild@0.27.7)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0)
+
   '@vitest/mocker@4.1.9(vite@8.0.16(@types/node@25.9.3)(esbuild@0.28.0)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0))':
     dependencies:
       '@vitest/spy': 4.1.9
@@ -9893,6 +9938,39 @@ snapshots:
       - supports-color
       - utf-8-validate
 
+  '@wdio/cli@9.28.0(@types/node@25.9.3)(expect-webdriverio@5.7.0)(puppeteer-core@21.11.0)':
+    dependencies:
+      '@vitest/snapshot': 2.1.9
+      '@wdio/config': 9.28.0
+      '@wdio/globals': 9.28.0(expect-webdriverio@5.7.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))
+      '@wdio/logger': 9.18.0
+      '@wdio/protocols': 9.28.0
+      '@wdio/types': 9.28.0
+      '@wdio/utils': 9.28.0
+      async-exit-hook: 2.0.1
+      chalk: 5.6.2
+      chokidar: 4.0.3
+      create-wdio: 9.28.0(@types/node@25.9.3)
+      dotenv: 17.4.2
+      import-meta-resolve: 4.2.0
+      lodash.flattendeep: 4.4.0
+      lodash.pickby: 4.6.0
+      lodash.union: 4.6.0
+      read-pkg-up: 10.1.0
+      tsx: 4.22.4
+      webdriverio: 9.28.0(puppeteer-core@21.11.0)
+      yargs: 17.7.2
+    transitivePeerDependencies:
+      - '@types/node'
+      - bare-abort-controller
+      - bare-buffer
+      - bufferutil
+      - expect-webdriverio
+      - puppeteer-core
+      - react-native-b4a
+      - supports-color
+      - utf-8-validate
+
   '@wdio/config@8.41.0':
     dependencies:
       '@wdio/logger': 8.38.0
@@ -9952,6 +10030,23 @@ snapshots:
       expect-webdriverio: 5.6.8(@wdio/globals@9.28.0)(@wdio/logger@9.29.1)(webdriverio@9.28.0(puppeteer-core@21.11.0))
       webdriverio: 9.28.0(puppeteer-core@21.11.0)
 
+  '@wdio/globals@9.28.0(expect-webdriverio@5.7.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))':
+    dependencies:
+      expect-webdriverio: 5.7.0(@wdio/globals@9.28.0)(@wdio/logger@9.29.1)(webdriverio@9.28.0(puppeteer-core@21.11.0))
+      webdriverio: 9.28.0(puppeteer-core@21.11.0)
+
+  '@wdio/globals@9.29.1(expect-webdriverio@5.7.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))':
+    dependencies:
+      expect-webdriverio: 5.7.0(@wdio/globals@9.29.1)(@wdio/logger@9.18.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))
+      webdriverio: 9.28.0(puppeteer-core@21.11.0)
+
+  '@wdio/image-comparison-core@2.1.0':
+    dependencies:
+      '@wdio/logger': 9.29.1
+      '@wdio/types': 9.29.1
+      fast-png: 8.0.0
+      pixelmatch: 7.2.0
+
   '@wdio/local-runner@9.28.0(@wdio/globals@9.28.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))':
     dependencies:
       '@types/node': 25.9.3
@@ -10119,6 +10214,16 @@ snapshots:
       - react-native-b4a
       - supports-color
 
+  '@wdio/visual-service@10.1.0(webdriverio@9.28.0(puppeteer-core@21.11.0))':
+    dependencies:
+      '@wdio/globals': 9.29.1(expect-webdriverio@5.7.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))
+      '@wdio/image-comparison-core': 2.1.0
+      '@wdio/logger': 9.29.1
+      '@wdio/types': 9.29.1
+      expect-webdriverio: 5.7.0(@wdio/globals@9.29.1)(@wdio/logger@9.29.1)(webdriverio@9.28.0(puppeteer-core@21.11.0))
+    transitivePeerDependencies:
+      - webdriverio
+
   '@wdio/xvfb@9.28.0':
     dependencies:
       '@wdio/logger': 9.18.0
@@ -10149,7 +10254,7 @@ snapshots:
 
   agent-base@6.0.2:
     dependencies:
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
     transitivePeerDependencies:
       - supports-color
 
@@ -11252,7 +11357,7 @@ snapshots:
 
   edgedriver@6.3.0:
     dependencies:
-      '@wdio/logger': 9.29.1
+      '@wdio/logger': 9.18.0
       '@zip.js/zip.js': 2.8.26
       decamelize: 6.0.1
       edge-paths: 3.0.5
@@ -11597,7 +11702,7 @@ snapshots:
       '@types/estree': 1.0.9
       ajv: 6.15.0
       cross-spawn: 7.0.6
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       escape-string-regexp: 4.0.0
       eslint-scope: 9.1.2
       eslint-visitor-keys: 5.0.1
@@ -11709,6 +11814,36 @@ snapshots:
       jest-matcher-utils: 30.4.1
       webdriverio: 9.28.0(puppeteer-core@21.11.0)
 
+  expect-webdriverio@5.7.0(@wdio/globals@9.28.0)(@wdio/logger@9.29.1)(webdriverio@9.28.0(puppeteer-core@21.11.0)):
+    dependencies:
+      '@vitest/snapshot': 4.1.9
+      '@wdio/globals': 9.28.0(expect-webdriverio@5.7.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))
+      '@wdio/logger': 9.29.1
+      deep-eql: 5.0.2
+      expect: 30.4.1
+      jest-matcher-utils: 30.4.1
+      webdriverio: 9.28.0(puppeteer-core@21.11.0)
+
+  expect-webdriverio@5.7.0(@wdio/globals@9.29.1)(@wdio/logger@9.18.0)(webdriverio@9.28.0(puppeteer-core@21.11.0)):
+    dependencies:
+      '@vitest/snapshot': 4.1.9
+      '@wdio/globals': 9.29.1(expect-webdriverio@5.7.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))
+      '@wdio/logger': 9.18.0
+      deep-eql: 5.0.2
+      expect: 30.4.1
+      jest-matcher-utils: 30.4.1
+      webdriverio: 9.28.0(puppeteer-core@21.11.0)
+
+  expect-webdriverio@5.7.0(@wdio/globals@9.29.1)(@wdio/logger@9.29.1)(webdriverio@9.28.0(puppeteer-core@21.11.0)):
+    dependencies:
+      '@vitest/snapshot': 4.1.9
+      '@wdio/globals': 9.29.1(expect-webdriverio@5.7.0)(webdriverio@9.28.0(puppeteer-core@21.11.0))
+      '@wdio/logger': 9.29.1
+      deep-eql: 5.0.2
+      expect: 30.4.1
+      jest-matcher-utils: 30.4.1
+      webdriverio: 9.28.0(puppeteer-core@21.11.0)
+
   expect@30.4.1:
     dependencies:
       '@jest/expect-utils': 30.4.1
@@ -11724,7 +11859,7 @@ snapshots:
 
   extract-zip@2.0.1:
     dependencies:
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       get-stream: 5.2.0
       yauzl: 2.10.0
     optionalDependencies:
@@ -11763,6 +11898,11 @@ snapshots:
 
   fast-levenshtein@2.0.6: {}
 
+  fast-png@8.0.0:
+    dependencies:
+      fflate: 0.8.3
+      iobuffer: 6.0.1
+
   fast-querystring@1.1.2:
     dependencies:
       fast-decode-uri-component: 1.0.1
@@ -11993,7 +12133,7 @@ snapshots:
 
   geckodriver@6.1.0:
     dependencies:
-      '@wdio/logger': 9.29.1
+      '@wdio/logger': 9.18.0
       '@zip.js/zip.js': 2.8.26
       decamelize: 6.0.1
       http-proxy-agent: 7.0.2
@@ -12055,7 +12195,7 @@ snapshots:
     dependencies:
       basic-ftp: 5.3.1
       data-uri-to-buffer: 6.0.2
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
     transitivePeerDependencies:
       - supports-color
 
@@ -12063,7 +12203,7 @@ snapshots:
     dependencies:
       basic-ftp: 5.3.1
       data-uri-to-buffer: 8.0.0
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
     transitivePeerDependencies:
       - supports-color
 
@@ -12261,35 +12401,35 @@ snapshots:
   http-proxy-agent@7.0.2:
     dependencies:
       agent-base: 7.1.4
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
     transitivePeerDependencies:
       - supports-color
 
   http-proxy-agent@9.0.0:
     dependencies:
       agent-base: 9.0.0
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
     transitivePeerDependencies:
       - supports-color
 
   https-proxy-agent@5.0.1:
     dependencies:
       agent-base: 6.0.2
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
     transitivePeerDependencies:
       - supports-color
 
   https-proxy-agent@7.0.6:
     dependencies:
       agent-base: 7.1.4
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
     transitivePeerDependencies:
       - supports-color
 
   https-proxy-agent@9.0.0:
     dependencies:
       agent-base: 9.0.0
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
     transitivePeerDependencies:
       - supports-color
 
@@ -12370,6 +12510,8 @@ snapshots:
       hasown: 2.0.4
       side-channel: 1.1.0
 
+  iobuffer@6.0.1: {}
+
   ip-address@10.2.0: {}
 
   ip-regex@4.3.0: {}
@@ -12588,7 +12730,7 @@ snapshots:
   istanbul-lib-source-maps@5.0.6:
     dependencies:
       '@jridgewell/trace-mapping': 0.3.31
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       istanbul-lib-coverage: 3.2.2
     transitivePeerDependencies:
       - supports-color
@@ -13051,7 +13193,7 @@ snapshots:
 
   lighthouse-logger@2.0.2:
     dependencies:
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       marky: 1.3.0
     transitivePeerDependencies:
       - supports-color
@@ -13680,7 +13822,7 @@ snapshots:
     dependencies:
       '@tootallnate/quickjs-emscripten': 0.23.0
       agent-base: 7.1.4
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       get-uri: 6.0.5
       http-proxy-agent: 7.0.2
       https-proxy-agent: 7.0.6
@@ -13692,7 +13834,7 @@ snapshots:
   pac-proxy-agent@9.0.1:
     dependencies:
       agent-base: 9.0.0
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       get-uri: 8.0.0
       http-proxy-agent: 9.0.0
       https-proxy-agent: 9.0.0
@@ -13858,6 +14000,10 @@ snapshots:
     optionalDependencies:
       '@napi-rs/nice': 1.1.1
 
+  pixelmatch@7.2.0:
+    dependencies:
+      pngjs: 7.0.0
+
   pkg-dir@4.2.0:
     dependencies:
       find-up: 4.1.0
@@ -13969,7 +14115,7 @@ snapshots:
   proxy-agent@6.3.1:
     dependencies:
       agent-base: 7.1.4
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       http-proxy-agent: 7.0.2
       https-proxy-agent: 7.0.6
       lru-cache: 7.18.3
@@ -13982,7 +14128,7 @@ snapshots:
   proxy-agent@6.5.0:
     dependencies:
       agent-base: 7.1.4
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       http-proxy-agent: 7.0.2
       https-proxy-agent: 7.0.6
       lru-cache: 7.18.3
@@ -13995,7 +14141,7 @@ snapshots:
   proxy-agent@8.0.1:
     dependencies:
       agent-base: 9.0.0
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       http-proxy-agent: 9.0.0
       https-proxy-agent: 9.0.0
       lru-cache: 7.18.3
@@ -14492,7 +14638,7 @@ snapshots:
 
   simple-update-notifier@2.0.0:
     dependencies:
-      semver: 7.8.1
+      semver: 7.8.4
 
   sirv@3.0.2:
     dependencies:
@@ -14515,7 +14661,7 @@ snapshots:
   socks-proxy-agent@10.0.0:
     dependencies:
       agent-base: 9.0.0
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       socks: 2.8.9
     transitivePeerDependencies:
       - supports-color
@@ -14523,7 +14669,7 @@ snapshots:
   socks-proxy-agent@8.0.5:
     dependencies:
       agent-base: 7.1.4
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       socks: 2.8.9
     transitivePeerDependencies:
       - supports-color
@@ -14732,7 +14878,7 @@ snapshots:
       cosmiconfig: 9.0.2(typescript@6.0.3)
       css-functions-list: 3.3.3
       css-tree: 3.2.1
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       fast-glob: 3.3.3
       fastest-levenshtein: 1.0.16
       file-entry-cache: 11.1.3
@@ -14995,7 +15141,7 @@ snapshots:
       cac: 6.7.14
       chokidar: 4.0.3
       consola: 3.4.2
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       esbuild: 0.27.7
       fix-dts-default-cjs-exports: 1.0.1
       joycon: 3.1.1
@@ -15128,7 +15274,7 @@ snapshots:
       '@rollup/pluginutils': 5.4.0(rollup@4.62.0)
       '@volar/typescript': 2.4.28
       compare-versions: 6.1.1
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
       kolorist: 1.8.0
       local-pkg: 1.2.1
       magic-string: 0.30.21
@@ -15271,6 +15417,21 @@ snapshots:
     optionalDependencies:
       rollup: 4.62.0
 
+  vite@8.0.16(@types/node@25.9.3)(esbuild@0.27.7)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0):
+    dependencies:
+      lightningcss: 1.32.0
+      picomatch: 4.0.4
+      postcss: 8.5.15
+      rolldown: 1.0.3
+      tinyglobby: 0.2.17
+    optionalDependencies:
+      '@types/node': 25.9.3
+      esbuild: 0.27.7
+      fsevents: 2.3.3
+      jiti: 2.7.0
+      tsx: 4.22.4
+      yaml: 2.9.0
+
   vite@8.0.16(@types/node@25.9.3)(esbuild@0.28.0)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0):
     dependencies:
       lightningcss: 1.32.0
@@ -15286,6 +15447,36 @@ snapshots:
       tsx: 4.22.4
       yaml: 2.9.0
 
+  vitest@4.1.9(@types/node@25.9.3)(@vitest/coverage-v8@4.1.9)(happy-dom@20.10.4)(jsdom@24.1.3)(vite@8.0.16(@types/node@25.9.3)(esbuild@0.27.7)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0)):
+    dependencies:
+      '@vitest/expect': 4.1.9
+      '@vitest/mocker': 4.1.9(vite@8.0.16(@types/node@25.9.3)(esbuild@0.27.7)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0))
+      '@vitest/pretty-format': 4.1.9
+      '@vitest/runner': 4.1.9
+      '@vitest/snapshot': 4.1.9
+      '@vitest/spy': 4.1.9
+      '@vitest/utils': 4.1.9
+      es-module-lexer: 2.1.0
+      expect-type: 1.3.0
+      magic-string: 0.30.21
+      obug: 2.1.3
+      pathe: 2.0.3
+      picomatch: 4.0.4
+      std-env: 4.1.0
+      tinybench: 2.9.0
+      tinyexec: 1.2.4
+      tinyglobby: 0.2.17
+      tinyrainbow: 3.1.0
+      vite: 8.0.16(@types/node@25.9.3)(esbuild@0.27.7)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0)
+      why-is-node-running: 2.3.0
+    optionalDependencies:
+      '@types/node': 25.9.3
+      '@vitest/coverage-v8': 4.1.9(@vitest/browser@4.1.9)(vitest@4.1.9)
+      happy-dom: 20.10.4
+      jsdom: 24.1.3
+    transitivePeerDependencies:
+      - msw
+
   vitest@4.1.9(@types/node@25.9.3)(@vitest/coverage-v8@4.1.9)(happy-dom@20.10.4)(jsdom@24.1.3)(vite@8.0.16(@types/node@25.9.3)(esbuild@0.28.0)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0)):
     dependencies:
       '@vitest/expect': 4.1.9
@@ -15328,7 +15519,7 @@ snapshots:
     dependencies:
       chalk: 4.1.2
       commander: 9.5.0
-      debug: 4.4.3(supports-color@5.5.0)
+      debug: 4.4.3(supports-color@10.2.2)
     transitivePeerDependencies:
       - supports-color
 
diff --git a/test/README.md b/test/README.md
new file mode 100644
index 00000000..d6345591
--- /dev/null
+++ b/test/README.md
@@ -0,0 +1,77 @@
+# Cross-adapter verification harness
+
+Automates the per-adapter verification that was previously manual: run each
+framework's example, open the trace, and eyeball that capture is complete and
+the UI renders it. Instead:
+
+- **`pnpm verify`** — Layer A: loads each committed golden `trace.zip` through
+  the real backend reader, reduces it to a capture summary, and snapshots it.
+  Fast, no browser, runs in CI.
+- **`pnpm verify:ui`** — Layer B (Phase 2): boots the player against each fixture
+  and visual-diffs every panel. Local, needs a browser.
+- **`pnpm fixtures:regen`** — the one browser step: re-runs the examples in trace
+  mode and refreshes the committed fixtures.
+
+## Layout
+
+```
+test/
+├─ capture/
+│  ├─ matrix.ts              entry table (adapters × runners) — the only file that knows adapters
+│  ├─ summarize.ts           trace → deterministic capture summary (the snapshotted value)
+│  ├─ capture-parity.test.ts expect(summarize(trace)).toMatchSnapshot() per entry
+│  └─ __snapshots__/         committed golden summaries
+├─ support/
+│  ├─ paths.ts               repo/test roots + fixture paths
+│  └─ find-zip.ts            newest-zip finder (used by regen)
+├─ fixtures/<id>/trace.zip   committed golden fixtures (one folder per entry)
+├─ regen.ts                  regenerate fixtures (browser step)
+└─ vitest.config.ts          standalone project (kept out of `pnpm test`)
+```
+
+## How it works
+
+`verify` runs against **committed fixtures**, not live browsers. The fixture is a
+frozen known-good input:
+
+- **Change the app / reader / UI** → `verify` catches a regression against the
+  frozen fixture, no browser.
+- **Change capture** (an adapter, the exporter, the collector) → run
+  `fixtures:regen`, then `verify:update` to accept the new snapshot (an intended
+  change) or read the diff as a regression.
+
+CI closes the "forgot to regen" gap by re-running `fixtures:regen` when a
+capture-layer path changes (see `.github/workflows/`).
+
+## Commands
+
+```sh
+pnpm verify                    # Layer A — snapshot check (no browser)
+pnpm verify:watch              # watch mode
+pnpm verify:update             # seed/accept snapshots after a regen (vitest -u)
+pnpm fixtures:regen            # regenerate all ready fixtures (needs Chrome)
+pnpm fixtures:regen wdio-mocha # regenerate one entry by id
+```
+
+A fixture that doesn't exist yet skips its entry, so `verify` is green on a fresh
+clone until you run `fixtures:regen`. **First run:** after the first
+`fixtures:regen`, run `pnpm verify:update` once to write the initial snapshots
+(vitest does not auto-create them); thereafter `pnpm verify` checks against them.
+
+## Extending
+
+Add a runner by adding a row to [`capture/matrix.ts`](./capture/matrix.ts):
+its `command`, `cleanDirs`, and `traceOutputGlobs`. Nothing else enumerates
+adapters. Set `status: 'ready'` once the example produces a trace.
+
+## Status
+
+Five entries are `ready` with committed fixtures: WebdriverIO mocha + cucumber,
+Selenium mocha + cucumber, Nightwatch BDD.
+
+`nightwatch-cucumber` has a working example (it runs and captures per-scenario in
+trace mode) but is `planned` — a **documented limitation**: Nightwatch's cucumber
+runner uses a browser session per scenario, so the adapter's session-scoped trace
+export (written once at run-end) has no single live session to finalize and writes
+no `trace.zip`. The harness surfaced it; it's tracked in CLAUDE.md known debt.
+Flip to `ready` once `@wdio/nightwatch-devtools` supports per-scenario trace writing.
diff --git a/test/capture/__snapshots__/capture-parity.test.ts.snap b/test/capture/__snapshots__/capture-parity.test.ts.snap
new file mode 100644
index 00000000..bfd6fcfb
--- /dev/null
+++ b/test/capture/__snapshots__/capture-parity.test.ts.snap
@@ -0,0 +1,109 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`Nightwatch · BDD (describe/it) [nightwatch-bdd] > captures a consistent trace shape 1`] = `
+{
+  "commandVocabulary": [
+    "titleContains",
+    "url",
+  ],
+  "groups": {
+    "maxDepth": 2,
+    "topLevel": 1,
+  },
+  "hasConsole": true,
+  "hasFrames": true,
+  "hasMutations": true,
+  "hasNetwork": true,
+  "hasSources": true,
+  "hasTranscript": true,
+}
+`;
+
+exports[`Selenium · cucumber [selenium-cucumber] > captures a consistent trace shape 1`] = `
+{
+  "commandVocabulary": [
+    "assert.match",
+    "click",
+    "getText",
+    "getUrl",
+    "setValue",
+    "url",
+  ],
+  "groups": {
+    "maxDepth": 3,
+    "topLevel": 1,
+  },
+  "hasConsole": true,
+  "hasFrames": true,
+  "hasMutations": true,
+  "hasNetwork": true,
+  "hasSources": true,
+  "hasTranscript": true,
+}
+`;
+
+exports[`Selenium · mocha [selenium-mocha] > captures a consistent trace shape 1`] = `
+{
+  "commandVocabulary": [
+    "assert.equal",
+    "assert.match",
+    "getText",
+    "getTitle",
+    "url",
+  ],
+  "groups": {
+    "maxDepth": 2,
+    "topLevel": 1,
+  },
+  "hasConsole": true,
+  "hasFrames": true,
+  "hasMutations": true,
+  "hasNetwork": true,
+  "hasSources": true,
+  "hasTranscript": true,
+}
+`;
+
+exports[`WebdriverIO · cucumber [wdio-cucumber] > captures a consistent trace shape 1`] = `
+{
+  "commandVocabulary": [
+    "click",
+    "setValue",
+    "toExist",
+    "toHaveText",
+    "url",
+  ],
+  "groups": {
+    "maxDepth": 2,
+    "topLevel": 2,
+  },
+  "hasConsole": true,
+  "hasFrames": true,
+  "hasMutations": true,
+  "hasNetwork": true,
+  "hasSources": true,
+  "hasTranscript": true,
+}
+`;
+
+exports[`WebdriverIO · mocha [wdio-mocha] > captures a consistent trace shape 1`] = `
+{
+  "commandVocabulary": [
+    "click",
+    "setValue",
+    "toExist",
+    "toHaveText",
+    "url",
+  ],
+  "groups": {
+    "maxDepth": 1,
+    "topLevel": 2,
+  },
+  "hasConsole": true,
+  "hasFrames": true,
+  "hasMutations": true,
+  "hasNetwork": true,
+  "hasSources": true,
+  "hasTranscript": true,
+}
+`;
diff --git a/test/capture/capture-parity.test.ts b/test/capture/capture-parity.test.ts
new file mode 100644
index 00000000..9b3650e3
--- /dev/null
+++ b/test/capture/capture-parity.test.ts
@@ -0,0 +1,30 @@
+// Layer A — cross-adapter capture parity. Loads each committed golden trace.zip
+// through the real backend reader, reduces it to a capture summary, and
+// snapshots it. No browser: it reads fixtures produced by `pnpm fixtures:regen`.
+//
+// A fixture that isn't present yet (fresh clone / CI before a regen) skips its
+// entry, so the suite is green without fixtures and meaningful once they exist.
+// A capture change surfaces as a snapshot diff on that adapter — accept it with
+// `pnpm verify:update` (an intended change) or fix it (a regression).
+
+import { existsSync } from 'node:fs'
+
+import { describe, expect, it } from 'vitest'
+
+import { readTraceZip } from '../../packages/backend/src/trace-reader.js'
+import { fixtureTrace } from '../support/paths.js'
+
+import { READY_ENTRIES } from './matrix.js'
+import { summarizeCapture } from './summarize.js'
+
+for (const entry of READY_ENTRIES) {
+  const fixture = fixtureTrace(entry.id)
+  const present = existsSync(fixture)
+
+  describe.skipIf(!present)(`${entry.label} [${entry.id}]`, () => {
+    it('captures a consistent trace shape', async () => {
+      const data = await readTraceZip(fixture)
+      expect(summarizeCapture(data)).toMatchSnapshot()
+    })
+  })
+}
diff --git a/test/capture/matrix.ts b/test/capture/matrix.ts
new file mode 100644
index 00000000..432766a6
--- /dev/null
+++ b/test/capture/matrix.ts
@@ -0,0 +1,134 @@
+// The cross-adapter verification matrix. One entry per (adapter, runner)
+// example the harness drives through the same login flow. Adding a runner later
+// = adding a row here; nothing else in the harness enumerates adapters.
+//
+// `regen.ts` uses `command` + `traceOutputGlobs` to produce and collect a golden
+// fixture; `capture-parity.test.ts` loads the fixture and snapshots its capture
+// summary. The two stay in sync through this file.
+
+export type AdapterId = 'wdio' | 'selenium' | 'nightwatch'
+export type RunnerId = 'mocha' | 'cucumber' | 'bdd'
+
+export interface VerificationEntry {
+  /** Stable slug — also the fixture folder name under `test/fixtures/`. */
+  id: string
+  adapter: AdapterId
+  runner: RunnerId
+  label: string
+  /** `ready` entries regen + verify; `planned` are documented gaps skipped by
+   *  both (kept here so the matrix shows the whole intended surface). */
+  status: 'ready' | 'planned'
+  /** Why a `planned` entry can't run yet. */
+  plannedReason?: string
+  /** Command to produce a trace, spawned from the repo root with
+   *  `DEVTOOLS_MODE=trace` in the environment. */
+  command: { cmd: string; args: string[] }
+  /** Directories cleaned before a regen run so "newest zip" is unambiguous. */
+  cleanDirs: string[]
+  /** Globs (repo-root-relative) the produced `trace.zip` lands under; the
+   *  newest match is collected as the fixture. */
+  traceOutputGlobs: string[]
+}
+
+export const ENTRIES: VerificationEntry[] = [
+  {
+    id: 'wdio-mocha',
+    adapter: 'wdio',
+    runner: 'mocha',
+    label: 'WebdriverIO · mocha',
+    status: 'ready',
+    command: {
+      cmd: 'npx',
+      args: ['wdio', 'run', './examples/wdio/mocha/wdio.trace.conf.ts']
+    },
+    cleanDirs: ['examples/wdio/mocha/test-results'],
+    traceOutputGlobs: ['examples/wdio/mocha/test-results/**/trace*.zip']
+  },
+  {
+    id: 'wdio-cucumber',
+    adapter: 'wdio',
+    runner: 'cucumber',
+    label: 'WebdriverIO · cucumber',
+    status: 'ready',
+    command: {
+      cmd: 'npx',
+      args: ['wdio', 'run', './examples/wdio/cucumber/wdio.trace.conf.ts']
+    },
+    cleanDirs: ['examples/wdio/cucumber/test-results'],
+    traceOutputGlobs: ['examples/wdio/cucumber/test-results/**/trace*.zip']
+  },
+  {
+    id: 'selenium-mocha',
+    adapter: 'selenium',
+    runner: 'mocha',
+    label: 'Selenium · mocha',
+    status: 'ready',
+    command: {
+      cmd: 'pnpm',
+      args: ['--filter', '@wdio/selenium-devtools', 'example:mocha']
+    },
+    cleanDirs: [
+      'examples/selenium/mocha-test/test/test-results',
+      'examples/selenium/mocha-test/allure-results'
+    ],
+    traceOutputGlobs: [
+      'examples/selenium/mocha-test/test/test-results/**/trace*.zip'
+    ]
+  },
+  {
+    id: 'selenium-cucumber',
+    adapter: 'selenium',
+    runner: 'cucumber',
+    label: 'Selenium · cucumber',
+    status: 'ready',
+    command: {
+      cmd: 'pnpm',
+      args: ['--filter', '@wdio/selenium-devtools', 'example:cucumber']
+    },
+    cleanDirs: [
+      'examples/selenium/cucumber-test/features/support/test-results'
+    ],
+    traceOutputGlobs: [
+      'examples/selenium/cucumber-test/features/support/test-results/**/trace*.zip'
+    ]
+  },
+  {
+    id: 'nightwatch-bdd',
+    adapter: 'nightwatch',
+    runner: 'bdd',
+    label: 'Nightwatch · BDD (describe/it)',
+    status: 'ready',
+    command: {
+      cmd: 'pnpm',
+      args: ['--filter', '@wdio/nightwatch-devtools', 'example']
+    },
+    cleanDirs: ['examples/nightwatch/tests/test-results'],
+    traceOutputGlobs: ['examples/nightwatch/tests/test-results/**/trace*.zip']
+  },
+  {
+    id: 'nightwatch-cucumber',
+    adapter: 'nightwatch',
+    runner: 'cucumber',
+    label: 'Nightwatch · cucumber',
+    // Documented limitation: Nightwatch's cucumber runner launches a browser
+    // session PER SCENARIO, so the adapter's session-scoped trace export (written
+    // once at run-end) has no single live session to finalize and produces no
+    // trace.zip. The example runs and captures per-scenario in trace mode; only
+    // the session-zip export is missing. See CLAUDE.md known debt. Supporting it
+    // needs per-scenario trace writing in @wdio/nightwatch-devtools.
+    status: 'planned',
+    command: {
+      cmd: 'pnpm',
+      args: ['--filter', '@wdio/nightwatch-devtools', 'example:cucumber']
+    },
+    cleanDirs: [
+      'examples/nightwatch/cucumber/test-results',
+      'examples/nightwatch/cucumber/features/step_definitions/test-results'
+    ],
+    traceOutputGlobs: [
+      'examples/nightwatch/cucumber/**/test-results/**/trace*.zip'
+    ]
+  }
+]
+
+export const READY_ENTRIES = ENTRIES.filter((entry) => entry.status === 'ready')
diff --git a/test/capture/summarize.ts b/test/capture/summarize.ts
new file mode 100644
index 00000000..892e079f
--- /dev/null
+++ b/test/capture/summarize.ts
@@ -0,0 +1,61 @@
+// Reduces a reconstructed trace to a deterministic capture summary — the value
+// that gets snapshotted per adapter. Everything here must be stable across runs
+// (no timestamps, ids, counts that drift, or absolute paths), so the snapshot
+// only changes when capture behaviour actually changes.
+//
+// The command vocabulary (the sorted set of distinct command names) is the
+// sharp signal, and deliberately carries assertions too: each framework names
+// them differently and inconsistently — WebdriverIO `toExist`/`toHaveText`
+// (no result payload), Selenium `assert.*` (payload only on failure), Nightwatch
+// `titleContains` (with a `passed` flag) — so there is no clean cross-adapter
+// predicate for "is an assertion". The vocabulary sidesteps that: if an adapter
+// stops emitting its assertion (or any) rows, that name vanishes from the set
+// and the snapshot diff names it. No per-framework heuristic required.
+
+import type {
+  TraceActionChild,
+  TracePlayerData
+} from '../../packages/shared/src/trace-player.js'
+
+export interface CaptureSummary {
+  /** Sorted distinct command names captured — actions AND assertions. */
+  commandVocabulary: string[]
+  hasNetwork: boolean
+  hasConsole: boolean
+  hasMutations: boolean
+  hasSources: boolean
+  hasTranscript: boolean
+  hasFrames: boolean
+  /** Structural shape of the group tree (no titles — those carry run data). */
+  groups: { topLevel: number; maxDepth: number }
+}
+
+function groupDepth(child: TraceActionChild): number {
+  if ('group' in child) {
+    const children = child.group.children ?? []
+    return 1 + Math.max(0, ...children.map(groupDepth))
+  }
+  return 0
+}
+
+export function summarizeCapture(data: TracePlayerData): CaptureSummary {
+  const trace = data.trace
+  const roots = data.groups ?? []
+
+  return {
+    commandVocabulary: [
+      ...new Set(trace.commands.map((c) => c.command))
+    ].sort(),
+    hasNetwork: trace.networkRequests.length > 0,
+    hasConsole: trace.consoleLogs.length > 0,
+    hasMutations: trace.mutations.length > 0,
+    hasSources: Object.keys(trace.sources).length > 0,
+    hasTranscript:
+      typeof data.transcript === 'string' && data.transcript.length > 0,
+    hasFrames: data.frames.length > 0,
+    groups: {
+      topLevel: roots.filter((child) => 'group' in child).length,
+      maxDepth: Math.max(0, ...roots.map(groupDepth))
+    }
+  }
+}
diff --git a/test/fixtures/nightwatch-bdd/trace.zip b/test/fixtures/nightwatch-bdd/trace.zip
new file mode 100644
index 00000000..344da811
Binary files /dev/null and b/test/fixtures/nightwatch-bdd/trace.zip differ
diff --git a/test/fixtures/selenium-cucumber/trace.zip b/test/fixtures/selenium-cucumber/trace.zip
new file mode 100644
index 00000000..f59c4160
Binary files /dev/null and b/test/fixtures/selenium-cucumber/trace.zip differ
diff --git a/test/fixtures/selenium-mocha/trace.zip b/test/fixtures/selenium-mocha/trace.zip
new file mode 100644
index 00000000..8b5641ac
Binary files /dev/null and b/test/fixtures/selenium-mocha/trace.zip differ
diff --git a/test/fixtures/wdio-cucumber/trace.zip b/test/fixtures/wdio-cucumber/trace.zip
new file mode 100644
index 00000000..03323a3c
Binary files /dev/null and b/test/fixtures/wdio-cucumber/trace.zip differ
diff --git a/test/fixtures/wdio-mocha/trace.zip b/test/fixtures/wdio-mocha/trace.zip
new file mode 100644
index 00000000..3dfb611e
Binary files /dev/null and b/test/fixtures/wdio-mocha/trace.zip differ
diff --git a/test/regen.ts b/test/regen.ts
new file mode 100644
index 00000000..e982b9cb
--- /dev/null
+++ b/test/regen.ts
@@ -0,0 +1,81 @@
+// Regenerates the committed golden fixtures — the ONE browser-dependent step of
+// the harness. Run it deliberately when you intend to change capture, then
+// review the fixture diff (and `pnpm verify:update` the snapshots) and commit.
+// Everyday verification runs against the committed fixtures with no browser.
+//
+//   pnpm fixtures:regen            # all ready entries
+//   pnpm fixtures:regen wdio-mocha # one entry by id
+//
+// For each entry: clean its output dirs, run the example in trace mode
+// (DEVTOOLS_MODE=trace), find the newest produced trace.zip, and copy it to
+// test/fixtures/<id>/trace.zip.
+
+import { spawnSync } from 'node:child_process'
+import { copyFileSync, mkdirSync, rmSync } from 'node:fs'
+import path from 'node:path'
+
+import { READY_ENTRIES, type VerificationEntry } from './capture/matrix.js'
+import { findNewestZip } from './support/find-zip.js'
+import { fixtureTrace, REPO_ROOT } from './support/paths.js'
+
+function regen(entry: VerificationEntry): boolean {
+  console.log(`\n── ${entry.label} [${entry.id}] ──`)
+
+  for (const dir of entry.cleanDirs) {
+    rmSync(path.resolve(REPO_ROOT, dir), { recursive: true, force: true })
+  }
+
+  const { cmd, args } = entry.command
+  console.log(`  $ DEVTOOLS_MODE=trace ${cmd} ${args.join(' ')}`)
+  const run = spawnSync(cmd, args, {
+    cwd: REPO_ROOT,
+    stdio: 'inherit',
+    env: { ...process.env, DEVTOOLS_MODE: 'trace' },
+    shell: process.platform === 'win32'
+  })
+  if (run.status !== 0) {
+    console.warn(
+      `  ⚠ command exited with ${run.status ?? run.signal} — some examples fail on purpose; still collecting.`
+    )
+  }
+
+  const zip = findNewestZip(entry.traceOutputGlobs, REPO_ROOT)
+  if (!zip) {
+    console.error(
+      `  ✗ no trace.zip found under ${entry.traceOutputGlobs.join(', ')}`
+    )
+    return false
+  }
+
+  const dest = fixtureTrace(entry.id)
+  mkdirSync(path.dirname(dest), { recursive: true })
+  copyFileSync(zip, dest)
+  console.log(
+    `  ✓ ${path.relative(REPO_ROOT, zip)} → ${path.relative(REPO_ROOT, dest)}`
+  )
+  return true
+}
+
+const only = process.argv.slice(2)
+const targets = only.length
+  ? READY_ENTRIES.filter((e) => only.includes(e.id))
+  : READY_ENTRIES
+
+if (only.length && targets.length === 0) {
+  console.error(`No ready entry matches: ${only.join(', ')}`)
+  console.error(`Known: ${READY_ENTRIES.map((e) => e.id).join(', ')}`)
+  process.exit(1)
+}
+
+const results = targets.map((entry) => ({ id: entry.id, ok: regen(entry) }))
+const failed = results.filter((r) => !r.ok)
+
+console.log(
+  `\nRegenerated ${results.length - failed.length}/${results.length} fixtures.`
+)
+if (failed.length) {
+  console.log(
+    `Missing: ${failed.map((r) => r.id).join(', ')} — check the run output above (Chrome present? example wired for trace?).`
+  )
+  process.exit(1)
+}
diff --git a/test/support/find-zip.ts b/test/support/find-zip.ts
new file mode 100644
index 00000000..ba8d8b91
--- /dev/null
+++ b/test/support/find-zip.ts
@@ -0,0 +1,59 @@
+import { existsSync, readdirSync, statSync } from 'node:fs'
+import path from 'node:path'
+
+// Match a single-`*` basename glob (e.g. "trace*.zip") without a RegExp — the
+// matrix's globs always use one wildcard, so prefix/suffix matching suffices
+// and avoids a dynamic-RegExp lint/CodeQL flag.
+function basenameMatches(fileGlob: string, name: string): boolean {
+  const star = fileGlob.indexOf('*')
+  if (star === -1) {
+    return name === fileGlob
+  }
+  const prefix = fileGlob.slice(0, star)
+  const suffix = fileGlob.slice(star + 1)
+  return (
+    name.length >= prefix.length + suffix.length &&
+    name.startsWith(prefix) &&
+    name.endsWith(suffix)
+  )
+}
+
+// Resolve recursive "dir/<...>/trace*.zip" globs against a base dir and return
+// the newest matching file. No glob dependency — a small walk covers the fixed
+// shapes the matrix uses.
+function matchesFor(glob: string, repoRoot: string): string[] {
+  const wildcardAt = glob.indexOf('**')
+  const baseRel =
+    wildcardAt === -1 ? path.dirname(glob) : glob.slice(0, wildcardAt)
+  const baseAbs = path.resolve(repoRoot, baseRel)
+  const fileGlob = path.basename(glob)
+  if (!existsSync(baseAbs)) {
+    return []
+  }
+
+  const out: string[] = []
+  const walk = (dir: string): void => {
+    for (const dirent of readdirSync(dir, { withFileTypes: true })) {
+      const full = path.join(dir, dirent.name)
+      if (dirent.isDirectory()) {
+        walk(full)
+      } else if (basenameMatches(fileGlob, dirent.name)) {
+        out.push(full)
+      }
+    }
+  }
+  walk(baseAbs)
+  return out
+}
+
+/** Newest file matching any of the globs (repo-root-relative), or null. */
+export function findNewestZip(
+  globs: string[],
+  repoRoot: string
+): string | null {
+  const matches = globs.flatMap((glob) => matchesFor(glob, repoRoot))
+  if (matches.length === 0) {
+    return null
+  }
+  return matches.sort((a, b) => statSync(b).mtimeMs - statSync(a).mtimeMs)[0]
+}
diff --git a/test/support/paths.ts b/test/support/paths.ts
new file mode 100644
index 00000000..3273a4bb
--- /dev/null
+++ b/test/support/paths.ts
@@ -0,0 +1,20 @@
+import path from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+// Roots resolved from this file's location so the harness works regardless of
+// the process cwd (vitest, tsx regen, or a CI runner).
+export const TEST_ROOT = path.resolve(
+  path.dirname(fileURLToPath(import.meta.url)),
+  '..'
+)
+export const REPO_ROOT = path.resolve(TEST_ROOT, '..')
+
+/** Committed golden trace for an entry: `test/fixtures/<id>/trace.zip`. */
+export function fixtureTrace(id: string): string {
+  return path.join(TEST_ROOT, 'fixtures', id, 'trace.zip')
+}
+
+/** Recorded live event stream for an entry (Phase 1b). */
+export function fixtureLiveEvents(id: string): string {
+  return path.join(TEST_ROOT, 'fixtures', id, 'live-events.json')
+}
diff --git a/test/support/serve-fixture.ts b/test/support/serve-fixture.ts
new file mode 100644
index 00000000..276a5c0e
--- /dev/null
+++ b/test/support/serve-fixture.ts
@@ -0,0 +1,27 @@
+// Layer B support: boot the real backend in trace-serve mode against a
+// committed golden fixture so the WebdriverIO visual specs can drive the trace
+// player. Mirrors show-trace.ts (readTraceZip → start({ trace })), but returns
+// an instance-scoped close handle instead of opening a browser.
+
+import { readTraceZip } from '../../packages/backend/src/trace-reader.js'
+import { start } from '../../packages/backend/src/index.js'
+
+import { fixtureTrace } from './paths.js'
+
+export interface ServedFixture {
+  url: string
+  close: () => Promise<void>
+}
+
+/** Reconstruct the fixture trace, serve it, and hand back the player URL plus a
+ *  close handle. `start()` resolves to `{ server, port }`, so `server.close()`
+ *  is a real per-instance shutdown (the module-level `stop()` export closes the
+ *  last-started server, which would race parallel/sequential specs). */
+export async function serveFixture(id: string): Promise<ServedFixture> {
+  const trace = await readTraceZip(fixtureTrace(id))
+  const { server, port } = await start({ trace })
+  return {
+    url: `http://localhost:${port}`,
+    close: () => server.close()
+  }
+}
diff --git a/test/visual/.gitignore b/test/visual/.gitignore
new file mode 100644
index 00000000..6634a99a
--- /dev/null
+++ b/test/visual/.gitignore
@@ -0,0 +1,3 @@
+# Visual-service working dir — per-run actual + diff images. Only the committed
+# goldens under ./baseline are tracked.
+.tmp/
diff --git a/test/visual/README.md b/test/visual/README.md
new file mode 100644
index 00000000..3caf02c1
--- /dev/null
+++ b/test/visual/README.md
@@ -0,0 +1,34 @@
+# Layer B — visual regression
+
+Boots the trace **player** against each committed golden fixture and
+visual-snapshots every panel with WebdriverIO + [`@wdio/visual-service`].
+
+`player.e2e.ts` walks `READY_ENTRIES` from the capture matrix. For each entry it
+serves `fixtures/<id>/trace.zip` through the real backend (`serveFixture` →
+`readTraceZip` + `start({ trace })`), loads the player in headless Chrome, then
+snapshots the full player plus the timeline, controls, snapshot/viewport,
+actions, console, network, errors, and a11y panels. A block whose fixture is
+missing is skipped, so the suite is green on a fresh checkout and meaningful
+once fixtures exist.
+
+`dashboard.e2e.ts` is a skipped scaffold for the live dashboard — it awaits
+Phase 1b (`fixtures/<id>/live-events.json` + a live-serve helper).
+
+## Running
+
+```
+pnpm fixtures:regen                       # produce the golden trace.zip fixtures first
+npx wdio run test/visual/wdio.conf.ts
+```
+
+Requires `@wdio/visual-service` installed and a local Chrome/chromedriver.
+
+## Baselines
+
+Committed goldens live under `baseline/`. The config sets `autoSaveBaseline`, so
+the **first run seeds** the baselines — commit them, and later runs assert a 0%
+mismatch against them. Actual/diff images from a failing run land in `.tmp/`
+(not committed). An intended UI change is accepted by deleting the affected
+baseline images and re-running to reseed.
+
+[`@wdio/visual-service`]: https://webdriver.io/docs/visual-testing
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diff --git a/test/visual/dashboard.e2e.ts b/test/visual/dashboard.e2e.ts
new file mode 100644
index 00000000..b6dfe891
--- /dev/null
+++ b/test/visual/dashboard.e2e.ts
@@ -0,0 +1,20 @@
+// Layer B — live dashboard visual regression. SCAFFOLD ONLY.
+//
+// Unlike player.e2e.ts (which serves a static trace.zip), the live dashboard
+// needs a worker WebSocket streaming a recorded event feed into the backend.
+// That depends on Phase 1b: committed `fixtures/<id>/live-events.json` streams
+// plus a live-serve helper that boots the backend without `{ trace }` and
+// replays those events over the worker socket. Neither exists yet.
+//
+// This block stays skipped until then. Do NOT implement live serving here —
+// it lands with Phase 1b so the harness has a real feed to replay.
+
+import { READY_ENTRIES } from '../capture/matrix.js'
+
+describe.skip('live dashboard (awaits Phase 1b live fixtures)', () => {
+  for (const entry of READY_ENTRIES) {
+    it(`matches the live dashboard for ${entry.label}`, () => {
+      // Pending: serveLiveFixture(entry.id) → browser.url → snapshot panels.
+    })
+  }
+})
diff --git a/test/visual/player.e2e.ts b/test/visual/player.e2e.ts
new file mode 100644
index 00000000..bb32d84c
--- /dev/null
+++ b/test/visual/player.e2e.ts
@@ -0,0 +1,98 @@
+// Layer B — trace-player visual regression. For each ready matrix entry we serve
+// its committed golden fixture, load the player, and snapshot the whole player
+// plus every panel we have a stable selector for. A missing fixture skips the
+// block (fresh clone / CI before `pnpm fixtures:regen`), matching Layer A.
+//
+// The player is nested Lit shadow DOM with no data-testid, so panels are
+// addressed by their custom-element tag through the `>>>` deep combinator.
+// Dock panels (Console/Network/Errors/A11y) live inside inactive tabs; rather
+// than click through nested shadow roots we fire the same `open-dock-tab`
+// window event the app itself uses to switch tabs programmatically (tabs.ts).
+
+import fs from 'node:fs'
+
+import { browser, $, expect } from '@wdio/globals'
+
+import { READY_ENTRIES } from '../capture/matrix.js'
+import { fixtureTrace } from '../support/paths.js'
+import { serveFixture, type ServedFixture } from '../support/serve-fixture.js'
+
+const PLAYER_ROOT = 'wdio-devtools'
+// Only exists in player mode — the reliable "player has mounted" signal.
+const PLAYER_READY = '>>> wdio-devtools-trace-player-controls'
+
+// Max % of pixels allowed to differ. A small tolerance absorbs sub-pixel
+// anti-aliasing / font-hinting noise (and headed-vs-headless rendering); a real
+// UI change is far larger. Prevents brittle 0%-threshold failures.
+const MISMATCH_TOLERANCE = 0.1
+
+interface Panel {
+  name: string
+  selector: string
+  /** Dock-tab label to activate before snapshotting; omit for always-visible panels. */
+  tab?: string
+}
+
+const PANELS: Panel[] = [
+  { name: 'timeline', selector: '>>> wdio-devtools-trace-timeline' },
+  { name: 'controls', selector: '>>> wdio-devtools-trace-player-controls' },
+  { name: 'snapshot', selector: '>>> wdio-devtools-browser' },
+  { name: 'actions', selector: '>>> wdio-devtools-actions' },
+  {
+    name: 'console',
+    selector: '>>> wdio-devtools-console-logs',
+    tab: 'Console'
+  },
+  { name: 'network', selector: '>>> wdio-devtools-network', tab: 'Network' },
+  { name: 'errors', selector: '>>> wdio-devtools-errors', tab: 'Errors' },
+  { name: 'a11y', selector: '>>> wdio-devtools-a11y', tab: 'A11y' }
+]
+
+async function activateDockTab(label: string): Promise<void> {
+  await browser.execute((tab: string) => {
+    window.dispatchEvent(
+      new CustomEvent('open-dock-tab', { detail: { label: tab } })
+    )
+  }, label)
+}
+
+for (const entry of READY_ENTRIES) {
+  const present = fs.existsSync(fixtureTrace(entry.id))
+  const suite = present ? describe : describe.skip
+
+  suite(entry.label, () => {
+    let served: ServedFixture
+
+    before(async () => {
+      served = await serveFixture(entry.id)
+      await browser.url(served.url)
+      await $(PLAYER_ROOT).waitForExist({ timeout: 20000 })
+      await $(PLAYER_READY).waitForExist({ timeout: 20000 })
+    })
+
+    after(async () => {
+      await served?.close()
+    })
+
+    it('matches the full player', async () => {
+      await expect(browser).toMatchScreenSnapshot(
+        `player-${entry.id}`,
+        MISMATCH_TOLERANCE
+      )
+    })
+
+    for (const panel of PANELS) {
+      it(`matches the ${panel.name} panel`, async () => {
+        if (panel.tab) {
+          await activateDockTab(panel.tab)
+        }
+        const el = await $(panel.selector)
+        await el.waitForExist({ timeout: 10000 })
+        await expect(el).toMatchElementSnapshot(
+          `${entry.id}-${panel.name}`,
+          MISMATCH_TOLERANCE
+        )
+      })
+    }
+  })
+}
diff --git a/test/visual/wdio.conf.ts b/test/visual/wdio.conf.ts
new file mode 100644
index 00000000..0cf6476d
--- /dev/null
+++ b/test/visual/wdio.conf.ts
@@ -0,0 +1,75 @@
+import path from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+import type { Options } from '@wdio/types'
+
+// Layer B — visual regression. Drives the trace player served by
+// serve-fixture.ts and snapshots each panel via @wdio/visual-service.
+// Capabilities mirror examples/wdio/mocha/wdio.conf.ts so the player renders at
+// the same viewport the goldens were captured against.
+//
+// Headless is the default so baselines render deterministically across machines
+// and CI. Set HEADED=1 to watch the browser drive the player live — but headed
+// rendering can differ from the headless goldens, so use it to observe, not to
+// re-seed baselines.
+
+const here = path.dirname(fileURLToPath(import.meta.url))
+const headed = process.env.HEADED === '1' || process.env.HEADED === 'true'
+
+export const config: Options.Testrunner = {
+  runner: 'local',
+  autoCompileOpts: {
+    autoCompile: true,
+    tsNodeOpts: {
+      transpileOnly: true
+    }
+  },
+  specs: ['./*.e2e.ts'],
+  exclude: [],
+  maxInstances: 1,
+  capabilities: [
+    {
+      browserName: 'chrome',
+      // Opt out of BiDi: the player's nested shadow DOM is queried via the `>>>`
+      // deep combinator, which routes through BiDi browsingContext.locateNodes —
+      // that intermittently hangs ~60s (esp. headed) before falling back to
+      // Classic. Classic resolves the same elements reliably; screenshots are
+      // identical either way, so committed baselines are unaffected.
+      'wdio:enforceWebDriverClassic': true,
+      'goog:chromeOptions': {
+        args: [
+          ...(headed ? [] : ['--headless']),
+          '--disable-gpu',
+          '--remote-allow-origins=*',
+          '--window-size=1600,900'
+        ]
+      }
+    }
+  ],
+  logLevel: 'warn',
+  bail: 0,
+  waitforTimeout: 10000,
+  connectionRetryTimeout: 120000,
+  connectionRetryCount: 3,
+  framework: 'mocha',
+  reporters: ['spec'],
+  services: [
+    [
+      'visual',
+      {
+        baselineFolder: path.join(here, 'baseline'),
+        // Actual + diff images for a failing run; the committed goldens live in
+        // baselineFolder, so this stays out of git (see .gitignore/README).
+        screenshotPath: path.join(here, '.tmp'),
+        // First run has no baseline — seed it instead of failing, so a fresh
+        // checkout produces the goldens to commit.
+        autoSaveBaseline: true,
+        formatImageName: '{tag}-{width}x{height}-dpr{dpr}'
+      }
+    ]
+  ],
+  mochaOpts: {
+    ui: 'bdd',
+    timeout: 60000
+  }
+}
diff --git a/test/vitest.config.ts b/test/vitest.config.ts
new file mode 100644
index 00000000..cfe100db
--- /dev/null
+++ b/test/vitest.config.ts
@@ -0,0 +1,22 @@
+import path from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+import { defineConfig } from 'vitest/config'
+
+// Standalone from the root vitest project: the verification suite reads golden
+// fixtures (produced by `pnpm fixtures:regen`), so it must stay out of
+// `pnpm test` and the coverage gate. Run it with `pnpm verify`.
+const repoRoot = path.resolve(
+  path.dirname(fileURLToPath(import.meta.url)),
+  '..'
+)
+
+export default defineConfig({
+  root: repoRoot,
+  test: {
+    globals: true,
+    environment: 'node',
+    include: ['test/**/*.test.ts'],
+    exclude: ['**/node_modules/**', '**/dist/**']
+  }
+})