From 1ad6c458ae357a555e56f5103f24e7d010656d64 Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:10:04 +0300
Subject: [PATCH 01/18] docs(demo): describe bisect seed history

---
 demo-ecommerce/docs/git-bisect-seed-history.md | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 demo-ecommerce/docs/git-bisect-seed-history.md

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
new file mode 100644
index 00000000..34c67cde
--- /dev/null
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -0,0 +1,8 @@
+# Git Bisect Seed History
+
+This branch is intentionally shaped for future shaka-perf git bisect testing.
+Commits alternate between harmless demo maintenance and deterministic regression
+fixtures so category-specific bisect flows have clear first-bad targets.
+
+The regression fixtures are artificial by design, but each one is scoped to the
+demo app and kept easy to inspect.

From 8de754bd625f57d6ea352f9c332dbe4e7b7c1c8b Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:10:26 +0300
Subject: [PATCH 02/18] docs(demo): note clean bisect checkpoints

---
 demo-ecommerce/docs/git-bisect-seed-history.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index 34c67cde..7fd98ff1 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -6,3 +6,6 @@ fixtures so category-specific bisect flows have clear first-bad targets.
 
 The regression fixtures are artificial by design, but each one is scoped to the
 demo app and kept easy to inspect.
+
+Clean commits in this branch should stay runtime-neutral. They can update this
+note or other demo-only documentation without changing measured pages.

From 76ba1147ed2b0e5a74dfddb2543f90ebe9dce2a2 Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:10:46 +0300
Subject: [PATCH 03/18] test(demo): introduce homepage hero visual regression

---
 demo-ecommerce/app/javascript/components/pages/HomePage.tsx | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/demo-ecommerce/app/javascript/components/pages/HomePage.tsx b/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
index ed1e5079..c04ddb25 100644
--- a/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
+++ b/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
@@ -27,7 +27,7 @@ const HomePage: React.FC = () => {
       <Box
         data-cy="hero-section"
         sx={{
-          background: 'linear-gradient(135deg, #4f46b5 0%, #764ba2 100%)',
+          background: 'linear-gradient(135deg, #b45309 0%, #92400e 100%)',
           color: 'white',
           py: { xs: 6, md: 10 },
           mb: 6,

From 5c902c7fba1c6388ad4cd8afc91d54710db0d8d4 Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:11:05 +0300
Subject: [PATCH 04/18] docs(demo): clarify fixture route coverage

---
 demo-ecommerce/docs/git-bisect-seed-history.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index 7fd98ff1..68bb09f9 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -9,3 +9,6 @@ demo app and kept easy to inspect.
 
 Clean commits in this branch should stay runtime-neutral. They can update this
 note or other demo-only documentation without changing measured pages.
+
+Runtime fixtures should prefer existing measured routes so future bisect tests
+do not need a special-case demo configuration.

From 0e5e600c60aa5f8126c9559e1be6307d6addcbde Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:11:26 +0300
Subject: [PATCH 05/18] docs(demo): list covered storefront routes

---
 demo-ecommerce/docs/git-bisect-seed-history.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index 68bb09f9..bedfebb2 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -12,3 +12,7 @@ note or other demo-only documentation without changing measured pages.
 
 Runtime fixtures should prefer existing measured routes so future bisect tests
 do not need a special-case demo configuration.
+
+The homepage fixtures are intended for the existing homepage and shop-now
+coverage. The product detail fixture is intended for the existing product detail
+coverage.

From c2ee811e9fc4ea5bc1dde0a94f790f2378848552 Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:11:48 +0300
Subject: [PATCH 06/18] test(demo): introduce homepage performance regression

---
 .../javascript/components/pages/HomePage.tsx    | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/demo-ecommerce/app/javascript/components/pages/HomePage.tsx b/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
index c04ddb25..65ecc2ff 100644
--- a/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
+++ b/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
@@ -17,10 +17,27 @@ import LoadingSpinner from '../shared/LoadingSpinner';
 import LazySection from '../shared/LazySection';
 import ExperimentA11yRegressions from '../shared/ExperimentA11yRegressions';
 
+const runMerchandisingWarmup = () => {
+  const deadline = performance.now() + 450;
+  let checksum = 0;
+
+  while (performance.now() < deadline) {
+    checksum += Math.sqrt(checksum + 1);
+  }
+
+  if (checksum === Number.POSITIVE_INFINITY) {
+    console.info(checksum);
+  }
+};
+
 const HomePage: React.FC = () => {
   const { products, loading, error } = useProducts();
   const featuredProducts = products.filter((p) => p.featured).slice(0, 4);
 
+  React.useEffect(() => {
+    runMerchandisingWarmup();
+  }, []);
+
   return (
     <Box sx={{ bgcolor: '#f5f5f5', minHeight: '100vh' }}>
       {/* Hero Section */}

From 44cca911f7f606cc13955380877c7082cac961e0 Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:12:09 +0300
Subject: [PATCH 07/18] docs(demo): describe perf fixture style

---
 demo-ecommerce/docs/git-bisect-seed-history.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index bedfebb2..dd7c3cdf 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -16,3 +16,6 @@ do not need a special-case demo configuration.
 The homepage fixtures are intended for the existing homepage and shop-now
 coverage. The product detail fixture is intended for the existing product detail
 coverage.
+
+Performance fixtures should use deterministic client-side work instead of
+network delays so results remain easy to reproduce in local containers.

From e71c449dd18026da846356289c6b04e478b761cd Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:12:36 +0300
Subject: [PATCH 08/18] docs(demo): describe a11y fixture style

---
 demo-ecommerce/docs/git-bisect-seed-history.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index dd7c3cdf..f691e207 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -19,3 +19,6 @@ coverage.
 
 Performance fixtures should use deterministic client-side work instead of
 network delays so results remain easy to reproduce in local containers.
+
+Accessibility fixtures should avoid layout-visible changes when they are meant
+to be accessibility-only.

From 844590cd8a80ce4f5134ea0041e1412c819e0f20 Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:13:27 +0300
Subject: [PATCH 09/18] docs(demo): define clean commit expectations

---
 demo-ecommerce/docs/git-bisect-seed-history.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index f691e207..0d568995 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -22,3 +22,6 @@ network delays so results remain easy to reproduce in local containers.
 
 Accessibility fixtures should avoid layout-visible changes when they are meant
 to be accessibility-only.
+
+Clean commits should be safe to classify as good for every category that has
+not yet received its first dedicated regression fixture.

From 4f4434f1ff5400065e80a3179162cc998acafd27 Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:13:55 +0300
Subject: [PATCH 10/18] test(demo): introduce homepage accessibility regression

---
 .../app/javascript/components/pages/HomePage.tsx         | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/demo-ecommerce/app/javascript/components/pages/HomePage.tsx b/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
index 65ecc2ff..abf0ddfa 100644
--- a/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
+++ b/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
@@ -30,6 +30,14 @@ const runMerchandisingWarmup = () => {
   }
 };
 
+const BisectAccessibilityProbe: React.FC = () => (
+  <button
+    type="button"
+    data-cy="bisect-a11y-probe"
+    style={{ position: 'absolute', left: -10000, top: 0, width: 1, height: 1 }}
+  />
+);
+
 const HomePage: React.FC = () => {
   const { products, loading, error } = useProducts();
   const featuredProducts = products.filter((p) => p.featured).slice(0, 4);
@@ -84,6 +92,7 @@ const HomePage: React.FC = () => {
       </Box>
 
       <Container maxWidth="lg">
+        <BisectAccessibilityProbe />
         <ExperimentA11yRegressions />
 
         {/* Features Section */}

From 678abc68efd196500db76d0180a45fce00dc8868 Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:14:20 +0300
Subject: [PATCH 11/18] docs(demo): explain combined fixtures

---
 demo-ecommerce/docs/git-bisect-seed-history.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index 0d568995..03a95872 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -25,3 +25,6 @@ to be accessibility-only.
 
 Clean commits should be safe to classify as good for every category that has
 not yet received its first dedicated regression fixture.
+
+Combined regression commits are useful for checking that category-specific
+bisect still reports the earliest bad commit for each individual category.

From 5483ac5dc964b66ca3e92093f0ced88b13d31a3f Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:14:45 +0300
Subject: [PATCH 12/18] docs(demo): constrain product detail fixtures

---
 demo-ecommerce/docs/git-bisect-seed-history.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index 03a95872..55d1f9c1 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -28,3 +28,6 @@ not yet received its first dedicated regression fixture.
 
 Combined regression commits are useful for checking that category-specific
 bisect still reports the earliest bad commit for each individual category.
+
+Product detail fixtures should avoid changing product data or cart behavior, so
+they remain independent of Rails seeds and API responses.

From a0af6e6b85218465007304b02ac86eb216487bdd Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:15:10 +0300
Subject: [PATCH 13/18] docs(demo): keep fixture commits inspectable

---
 demo-ecommerce/docs/git-bisect-seed-history.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index 55d1f9c1..5017ffb7 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -31,3 +31,6 @@ bisect still reports the earliest bad commit for each individual category.
 
 Product detail fixtures should avoid changing product data or cart behavior, so
 they remain independent of Rails seeds and API responses.
+
+Fixture commits should stay small enough that `git show` explains the category
+signal without requiring a full app run.

From bc79de2debd7b9a41218410cb2e66149063c1092 Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:15:40 +0300
Subject: [PATCH 14/18] test(demo): introduce product detail visual and perf
 regression

---
 .../components/pages/ProductDetailPage.tsx     | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/demo-ecommerce/app/javascript/components/pages/ProductDetailPage.tsx b/demo-ecommerce/app/javascript/components/pages/ProductDetailPage.tsx
index 62f98120..ae1a690a 100644
--- a/demo-ecommerce/app/javascript/components/pages/ProductDetailPage.tsx
+++ b/demo-ecommerce/app/javascript/components/pages/ProductDetailPage.tsx
@@ -24,11 +24,28 @@ import { useCart } from '../../hooks/useCart';
 import LoadingSpinner from '../shared/LoadingSpinner';
 import ProductFeatures from '../shared/ProductFeatures';
 
+const runRecommendationScoring = () => {
+  const deadline = performance.now() + 350;
+  let checksum = 0;
+
+  while (performance.now() < deadline) {
+    checksum += Math.sqrt(checksum + 1);
+  }
+
+  if (checksum === Number.POSITIVE_INFINITY) {
+    console.info(checksum);
+  }
+};
+
 const ProductDetailPage: React.FC = () => {
   const { id } = useParams<{ id: string }>();
   const { product, loading, error } = useProduct(Number(id));
   const { addToCart } = useCart();
 
+  React.useEffect(() => {
+    runRecommendationScoring();
+  }, []);
+
   if (loading) {
     return <LoadingSpinner />;
   }
@@ -78,6 +95,7 @@ const ProductDetailPage: React.FC = () => {
                 maxHeight: 400,
                 objectFit: 'cover',
                 borderRadius: 2,
+                boxShadow: '0 0 0 8px rgba(180, 83, 9, 0.35)',
               }}
             />
           </Box>

From 8012cc1c8e3eec0e9f86beddac41e732fe799e5d Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:16:14 +0300
Subject: [PATCH 15/18] docs(demo): map expanded bisect seed commits

---
 .../docs/git-bisect-seed-history.md           | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index 5017ffb7..c3441bbb 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -34,3 +34,22 @@ they remain independent of Rails seeds and API responses.
 
 Fixture commits should stay small enough that `git show` explains the category
 signal without requiring a full app run.
+
+Seed base: `38dae68` (`main` when this branch was created).
+
+Category map:
+
+- `f2cd5c9` - no regression, seed docs only.
+- `267da30` - no regression, docs only.
+- `aa1b86a` - first `visreg` bad commit, homepage hero color change.
+- `c9b2c71` - no regression, docs only.
+- `a24c926` - no regression, docs only.
+- `5d38dcf` - first `perf` bad commit, homepage CPU warmup.
+- `4dbb382` - no regression, docs only.
+- `af79caf` - no regression, docs only.
+- `c0adc35` - no regression, docs only.
+- `38e7882` - first `accessibility` bad commit, offscreen unnamed button.
+- `5956eb6` - no regression, docs only.
+- `db65ccd` - no regression, docs only.
+- `5c3dbad` - no regression, docs only.
+- `993637a` - visual plus performance regression on product detail.

From a5adce5e712c4b22a418b3ed46a8c71d87ec7449 Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 15:25:21 +0300
Subject: [PATCH 16/18] docs(demo): document bisect fixture impact

---
 .../docs/git-bisect-seed-history.md           | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index c3441bbb..f8ffacaf 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -53,3 +53,36 @@ Category map:
 - `db65ccd` - no regression, docs only.
 - `5c3dbad` - no regression, docs only.
 - `993637a` - visual plus performance regression on product detail.
+
+Expected affected AB tests and metrics:
+
+- `Homepage` / `visreg` - screenshot mismatch and diff pixels for
+  `[data-cy="hero-section"]` and `document` after the hero gradient changes.
+- `Homepage` / `perf` - primarily worse `TBT` and lower `LH Score` from the
+  450ms homepage CPU warmup. `speed-index`, `FCP`, and `LCP` can also move
+  depending on timing.
+- `Homepage` / `accessibility` - a new axe finding, expected to be
+  `button-name`, from `button[data-cy="bisect-a11y-probe"]`.
+- `Click Shop Now on the homepage` / `perf` - primarily worse `TBT` and lower
+  `LH Score` in the phone viewport because the test starts on `/` and runs the
+  homepage CPU warmup.
+- `Product Detail` / `visreg` - screenshot mismatch and diff pixels from the
+  product image `boxShadow`.
+- `Product Detail` / `perf` - primarily worse `TBT` and lower `LH Score` from
+  the 350ms product-detail CPU warmup.
+- `Product Detail - Show Product Journey Toggle` / `visreg` - likely full-page
+  screenshot mismatch from the product image `boxShadow` in the phone viewport.
+
+Expected unaffected AB tests:
+
+- `Product Detail - Desktop Actions` captures only
+  `[data-cy="product-actions-desktop"]`, so the product image `boxShadow` should
+  not appear in its screenshot.
+- `Click Reviews on Product Detail` and
+  `Product Details => Click on Reviews => Click on Deals` end on reviews or
+  deals pages and run as visual-only tests, so the product-detail image change
+  should not be captured.
+- `Products List`, `Cart`, `Carousel`, and `Admin` do not visit touched routes
+  or changed fixtures.
+- Product-detail accessibility should stay unchanged because no semantic
+  accessibility regression was added there.

From d25d667e95aaed79d76a950169b25adf20d7116b Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Sun, 12 Jul 2026 22:10:29 +0300
Subject: [PATCH 17/18] docs(demo): refresh bisect seed commit map

---
 .../docs/git-bisect-seed-history.md           | 30 ++++++++++---------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/demo-ecommerce/docs/git-bisect-seed-history.md b/demo-ecommerce/docs/git-bisect-seed-history.md
index f8ffacaf..0d4a422e 100644
--- a/demo-ecommerce/docs/git-bisect-seed-history.md
+++ b/demo-ecommerce/docs/git-bisect-seed-history.md
@@ -39,20 +39,22 @@ Seed base: `38dae68` (`main` when this branch was created).
 
 Category map:
 
-- `f2cd5c9` - no regression, seed docs only.
-- `267da30` - no regression, docs only.
-- `aa1b86a` - first `visreg` bad commit, homepage hero color change.
-- `c9b2c71` - no regression, docs only.
-- `a24c926` - no regression, docs only.
-- `5d38dcf` - first `perf` bad commit, homepage CPU warmup.
-- `4dbb382` - no regression, docs only.
-- `af79caf` - no regression, docs only.
-- `c0adc35` - no regression, docs only.
-- `38e7882` - first `accessibility` bad commit, offscreen unnamed button.
-- `5956eb6` - no regression, docs only.
-- `db65ccd` - no regression, docs only.
-- `5c3dbad` - no regression, docs only.
-- `993637a` - visual plus performance regression on product detail.
+- `623a1ae` - no regression, seed docs only.
+- `fe8900e` - no regression, docs only.
+- `58cc828` - first `visreg` bad commit, homepage hero color change.
+- `a55e7f4` - no regression, docs only.
+- `754fcd9` - no regression, docs only.
+- `9c7cfff` - first `perf` bad commit, homepage CPU warmup.
+- `744fe90` - no regression, docs only.
+- `ac38e53` - no regression, docs only.
+- `463c429` - no regression, docs only.
+- `fcb0e2b` - first `accessibility` bad commit, offscreen unnamed button.
+- `c1e2a62` - no regression, docs only.
+- `ce1f601` - no regression, docs only.
+- `3846371` - no regression, docs only.
+- `5345dff` - visual plus performance regression on product detail.
+- `088afb9` - no regression, docs only.
+- `4406a78` - no regression, fixture-impact docs only.
 
 Expected affected AB tests and metrics:
 

From 068c9fa8831e9a2280d30654b64ede1e0d1d520c Mon Sep 17 00:00:00 2001
From: Ramez Weissa <ramez@shakacode.com>
Date: Wed, 15 Jul 2026 16:41:49 +0300
Subject: [PATCH 18/18] test(demo): configure bisect acceptance fixtures

---
 demo-ecommerce/abtests.config.ts              |  17 +-
 .../javascript/components/pages/HomePage.tsx  |  16 +-
 .../bisect/__tests__/seed-history.test.ts     | 189 ++++++++++++++++++
 3 files changed, 213 insertions(+), 9 deletions(-)
 create mode 100644 packages/shaka-perf/src/compare/bisect/__tests__/seed-history.test.ts

diff --git a/demo-ecommerce/abtests.config.ts b/demo-ecommerce/abtests.config.ts
index 36241934..df938442 100644
--- a/demo-ecommerce/abtests.config.ts
+++ b/demo-ecommerce/abtests.config.ts
@@ -63,6 +63,7 @@ export default defineConfig({
       browser: 'chromium',
       args: ['--no-sandbox'],
     },
+    viewports: ['phone'],
     maxNumDiffPixels: 50,
     defaultMisMatchThreshold: 0.1,
   },
@@ -76,8 +77,9 @@ export default defineConfig({
     // `screenEmulation` are NOT set here — the viewport referenced from
     // shared.viewports owns them; the runner lowers them via
     // lhConfigForViewport.
+    viewports: ['phone'],
     lighthouseConfig: LIGHTHOUSE_CONFIG,
-    numberOfMeasurements: 10,
+    numberOfMeasurements: 8,
     pValueThreshold: 0.01,
   },
 
@@ -85,6 +87,19 @@ export default defineConfig({
     lighthouseConfig: LIGHTHOUSE_CONFIG,
   },
 
+  bisect: {
+    rebuildCommands: [
+      {
+        description: 'Install JavaScript dependencies',
+        command: 'yarn install --immutable',
+      },
+      {
+        description: 'Precompile application assets',
+        command: 'rm -rf public/packs tmp/cache && SECRET_KEY_BASE_DUMMY=1 ./bin/rails assets:precompile',
+      },
+    ],
+  },
+
   twinServers: {
     experimentDir: process.cwd(),
     controlDir: process.env.CONTROL_REPO_DIR || '../../shaka-perf-control/demo-ecommerce',
diff --git a/demo-ecommerce/app/javascript/components/pages/HomePage.tsx b/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
index abf0ddfa..fbd28b18 100644
--- a/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
+++ b/demo-ecommerce/app/javascript/components/pages/HomePage.tsx
@@ -17,6 +17,14 @@ import LoadingSpinner from '../shared/LoadingSpinner';
 import LazySection from '../shared/LazySection';
 import ExperimentA11yRegressions from '../shared/ExperimentA11yRegressions';
 
+const BisectAccessibilityProbe: React.FC = () => (
+  <button
+    type="button"
+    data-cy="bisect-a11y-probe"
+    style={{ position: 'absolute', left: -10000, top: 0, width: 1, height: 1 }}
+  />
+);
+
 const runMerchandisingWarmup = () => {
   const deadline = performance.now() + 450;
   let checksum = 0;
@@ -30,14 +38,6 @@ const runMerchandisingWarmup = () => {
   }
 };
 
-const BisectAccessibilityProbe: React.FC = () => (
-  <button
-    type="button"
-    data-cy="bisect-a11y-probe"
-    style={{ position: 'absolute', left: -10000, top: 0, width: 1, height: 1 }}
-  />
-);
-
 const HomePage: React.FC = () => {
   const { products, loading, error } = useProducts();
   const featuredProducts = products.filter((p) => p.featured).slice(0, 4);
diff --git a/packages/shaka-perf/src/compare/bisect/__tests__/seed-history.test.ts b/packages/shaka-perf/src/compare/bisect/__tests__/seed-history.test.ts
new file mode 100644
index 00000000..1b845cf8
--- /dev/null
+++ b/packages/shaka-perf/src/compare/bisect/__tests__/seed-history.test.ts
@@ -0,0 +1,189 @@
+/*
+ * Copyright (c) 2026 ShakaCode LLC.
+ *
+ * SPDX-License-Identifier: LicenseRef-ShakaPerf-1.0
+ *
+ * This file is part of ShakaPerf. Use is governed by The ShakaPerf
+ * License in LICENSE.md.
+ */
+
+import * as fs from 'node:fs';
+import * as path from 'node:path';
+import { applyCachedObservations, applyObservations, nextCandidate } from '../search';
+import type {
+  BisectCategory,
+  BisectSession,
+  BisectTarget,
+  TargetObservation,
+} from '../types';
+
+const seedCommits = [
+  '38dae6871b8b443dd1880269dacde951700e77cc',
+  '623a1ae6f39cb6cbddd550ecd33d83c670877d14',
+  'fe8900e2568f11d05e41d43ad62e0aa863017264',
+  '58cc828b7272cd69408fa4dc5cd36206dcd8846a',
+  'a55e7f44dea86afa94775cf448dc3e696c71ed33',
+  '754fcd9b72b5623118a9bc1fb84b87ec98e002e1',
+  '9c7cfff6c0ca9bd561f5bb9905a1b09ee3132d1e',
+  '744fe902ab6b087f761f2df7e1f52bcc2e88d1c1',
+  'ac38e5320e6c33b67474f445c15e3012e22fb491',
+  '463c4296e003fafe5dc4e23f5f43e805e555938d',
+  'fcb0e2b107a99c6e4edab01da114d4d83b3d7a94',
+  'c1e2a62486870b02354c0c5b8727f8944e4913a3',
+  'ce1f6015bfd01e05228d94affb788fe5f0d896a0',
+  '3846371172486d851b836883c54520cc1b844199',
+  '5345dffb62b761b9cb0e1516a6bbd4389a6cf642',
+  '088afb9342d8c4337361df177e3731550b096fc9',
+  '4406a7800cfec9af52e9f7e731a1ad59915ac227',
+  'f7b872f2a6d5817be15261b4d9f21a4f6814126f',
+];
+
+const seedRegressionsByCommit = {
+  '58cc828b7272cd69408fa4dc5cd36206dcd8846a': ['homepage-hero-visual'],
+  '9c7cfff6c0ca9bd561f5bb9905a1b09ee3132d1e': ['homepage-tbt'],
+  'fcb0e2b107a99c6e4edab01da114d4d83b3d7a94': ['homepage-button-name'],
+  '5345dffb62b761b9cb0e1516a6bbd4389a6cf642': [
+    'product-detail-visual',
+    'product-detail-tbt',
+  ],
+} as const;
+
+type SeedTargetId =
+  (typeof seedRegressionsByCommit)[keyof typeof seedRegressionsByCommit][number];
+
+const expectedFirstBad = {
+  'homepage-hero-visual': '58cc828b7272cd69408fa4dc5cd36206dcd8846a',
+  'homepage-tbt': '9c7cfff6c0ca9bd561f5bb9905a1b09ee3132d1e',
+  'homepage-button-name': 'fcb0e2b107a99c6e4edab01da114d4d83b3d7a94',
+  'product-detail-visual': '5345dffb62b761b9cb0e1516a6bbd4389a6cf642',
+  'product-detail-tbt': '5345dffb62b761b9cb0e1516a6bbd4389a6cf642',
+} as const;
+
+function target(
+  id: keyof typeof expectedFirstBad,
+  category: BisectCategory,
+  testFile: string,
+  testName: string,
+  subject: string,
+): BisectTarget {
+  return {
+    id,
+    category,
+    testFile,
+    testName,
+    viewport: 'desktop',
+    subject,
+    status: 'active',
+    goodIndex: 0,
+    badIndex: seedCommits.length - 1,
+    observations: {},
+  };
+}
+
+function observation(
+  targetId: string,
+  commitSha: string,
+  present: boolean,
+): TargetObservation {
+  return {
+    targetId,
+    commitSha,
+    present,
+    values: { fixture: true },
+    artifacts: [],
+  };
+}
+
+function seedSession(): BisectSession {
+  return {
+    version: 1,
+    status: 'running',
+    goodSha: seedCommits[0],
+    badSha: seedCommits.at(-1)!,
+    originalExperiment: { sha: seedCommits.at(-1)!, branch: 'codex/git-bisect-demo-history' },
+    selectedCategories: ['visreg', 'perf', 'accessibility'],
+    orderedCommits: seedCommits,
+    targets: [
+      target(
+        'homepage-hero-visual',
+        'visreg',
+        'demo-ecommerce/ab-tests/homepage.abtest.ts',
+        'Homepage',
+        '[data-cy="hero-section"]',
+      ),
+      target('homepage-tbt', 'perf', 'demo-ecommerce/ab-tests/homepage.abtest.ts', 'Homepage', 'TBT'),
+      target(
+        'homepage-button-name',
+        'accessibility',
+        'demo-ecommerce/ab-tests/homepage.abtest.ts',
+        'Homepage',
+        'button-name',
+      ),
+      target(
+        'product-detail-visual',
+        'visreg',
+        'demo-ecommerce/ab-tests/product-detail.abtest.ts',
+        'Product Detail',
+        'document',
+      ),
+      target(
+        'product-detail-tbt',
+        'perf',
+        'demo-ecommerce/ab-tests/product-detail.abtest.ts',
+        'Product Detail',
+        'TBT',
+      ),
+    ],
+    commitRuns: {},
+    startedAt: '2026-07-12T00:00:00.000Z',
+  };
+}
+
+describe('demo ecommerce bisect seed history fixture', () => {
+  it('clears persistent build output before precompiling each candidate', () => {
+    const configPath = path.resolve(
+      __dirname,
+      '../../../../../../demo-ecommerce/abtests.config.ts',
+    );
+
+    expect(fs.readFileSync(configPath, 'utf8')).toContain(
+      "command: 'rm -rf public/packs tmp/cache && SECRET_KEY_BASE_DUMMY=1 ./bin/rails assets:precompile'",
+    );
+  });
+
+  it('finds the documented first bad commit for every seeded regression target', () => {
+    let session = seedSession();
+
+    while (true) {
+      const normalized = applyCachedObservations(session);
+      const work = nextCandidate(normalized);
+      if (!work) {
+        session = normalized;
+        break;
+      }
+      const candidateIndex = seedCommits.indexOf(work.sha);
+      const regressionsPresent = new Set(
+        seedCommits
+          .slice(0, candidateIndex + 1)
+          .flatMap(
+            (sha) => seedRegressionsByCommit[sha as keyof typeof seedRegressionsByCommit] ?? [],
+          ),
+      );
+      session = applyObservations(normalized, work.sha, new Map(
+        work.targetIds.map((targetId) => [
+          targetId,
+          observation(
+            targetId,
+            work.sha,
+            regressionsPresent.has(targetId as SeedTargetId),
+          ),
+        ]),
+      ));
+    }
+
+    expect(Object.fromEntries(
+      session.targets.map((item) => [item.id, item.firstBadSha]),
+    )).toEqual(expectedFirstBad);
+    expect(session.targets.every((item) => item.status === 'found')).toBe(true);
+  });
+});