From f604d31d549783f23076461d735370bf5e6c678b Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Wed, 1 Jul 2026 08:30:06 +0000
Subject: [PATCH] Sync generated provider output

---
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 .../detector/detect-antipatterns-browser.js   | 47 +++++++++++++++++++
 .../detector/registry/antipatterns.mjs        | 11 +++++
 .../scripts/detector/rules/checks.mjs         | 36 ++++++++++++++
 39 files changed, 1222 insertions(+)

diff --git a/.agents/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.agents/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.agents/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.agents/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.agents/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.agents/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.agents/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.agents/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.agents/skills/impeccable/scripts/detector/rules/checks.mjs b/.agents/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.agents/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.agents/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.claude/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.claude/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.claude/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.claude/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.claude/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.claude/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.claude/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.claude/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.claude/skills/impeccable/scripts/detector/rules/checks.mjs b/.claude/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.claude/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.claude/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.cursor/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.cursor/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.cursor/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.cursor/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.cursor/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.cursor/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.cursor/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.cursor/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.cursor/skills/impeccable/scripts/detector/rules/checks.mjs b/.cursor/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.cursor/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.cursor/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.gemini/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.gemini/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.gemini/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.gemini/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.gemini/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.gemini/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.gemini/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.gemini/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.gemini/skills/impeccable/scripts/detector/rules/checks.mjs b/.gemini/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.gemini/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.gemini/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.github/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.github/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.github/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.github/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.github/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.github/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.github/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.github/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.github/skills/impeccable/scripts/detector/rules/checks.mjs b/.github/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.github/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.github/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.kiro/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.kiro/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.kiro/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.kiro/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.kiro/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.kiro/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.kiro/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.kiro/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.kiro/skills/impeccable/scripts/detector/rules/checks.mjs b/.kiro/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.kiro/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.kiro/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.opencode/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.opencode/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.opencode/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.opencode/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.opencode/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.opencode/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.opencode/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.opencode/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.opencode/skills/impeccable/scripts/detector/rules/checks.mjs b/.opencode/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.opencode/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.opencode/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.pi/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.pi/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.pi/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.pi/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.pi/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.pi/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.pi/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.pi/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.pi/skills/impeccable/scripts/detector/rules/checks.mjs b/.pi/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.pi/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.pi/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.qoder/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.qoder/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.qoder/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.qoder/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.qoder/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.qoder/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.qoder/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.qoder/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.qoder/skills/impeccable/scripts/detector/rules/checks.mjs b/.qoder/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.qoder/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.qoder/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.rovodev/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.rovodev/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.rovodev/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.rovodev/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.rovodev/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.rovodev/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.rovodev/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.rovodev/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.rovodev/skills/impeccable/scripts/detector/rules/checks.mjs b/.rovodev/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.rovodev/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.rovodev/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.trae-cn/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.trae-cn/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.trae-cn/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.trae-cn/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.trae-cn/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.trae-cn/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.trae-cn/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.trae-cn/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.trae-cn/skills/impeccable/scripts/detector/rules/checks.mjs b/.trae-cn/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.trae-cn/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.trae-cn/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.trae/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/.trae/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/.trae/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/.trae/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/.trae/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/.trae/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/.trae/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/.trae/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/.trae/skills/impeccable/scripts/detector/rules/checks.mjs b/.trae/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/.trae/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/.trae/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/plugin/skills/impeccable/scripts/detector/detect-antipatterns-browser.js b/plugin/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
index b2091c609..3bfc2de47 100644
--- a/plugin/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
+++ b/plugin/skills/impeccable/scripts/detector/detect-antipatterns-browser.js
@@ -478,6 +478,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
@@ -1172,6 +1183,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.
diff --git a/plugin/skills/impeccable/scripts/detector/registry/antipatterns.mjs b/plugin/skills/impeccable/scripts/detector/registry/antipatterns.mjs
index 99eb2da04..ec1045022 100644
--- a/plugin/skills/impeccable/scripts/detector/registry/antipatterns.mjs
+++ b/plugin/skills/impeccable/scripts/detector/registry/antipatterns.mjs
@@ -376,6 +376,17 @@ const ANTIPATTERNS = [
     skillSection: 'Visual Details',
     skillGuideline: 'repeating-gradient decorative stripes',
   },
+  {
+    id: 'codex-grid-background',
+    category: 'slop',
+    severity: 'advisory',
+    gated: 'gpt',
+    name: 'Decorative grid-line background',
+    description:
+      'A two-axis grid drawn with hairline linear-gradient layers ("1px, transparent 1px" on both axes) is a recurring generated-UI signature. Reserve grid overlays for actual canvas, map, blueprint, or measurement surfaces; elsewhere use product structure or a plain surface.',
+    skillSection: 'Visual Details',
+    skillGuideline: 'two-axis grid-line gradient background',
+  },
   {
     id: 'theater-slop-phrase',
     category: 'slop',
diff --git a/plugin/skills/impeccable/scripts/detector/rules/checks.mjs b/plugin/skills/impeccable/scripts/detector/rules/checks.mjs
index 747d9a10f..13bcdc224 100644
--- a/plugin/skills/impeccable/scripts/detector/rules/checks.mjs
+++ b/plugin/skills/impeccable/scripts/detector/rules/checks.mjs
@@ -573,6 +573,42 @@ function checkHtmlPatterns(html) {
     findings.push({ id: 'repeating-stripes-gradient', snippet: 'repeating-gradient decorative stripes' });
   }
 
+  // --- Provider tells (gated): two-axis grid-line background (Codex/GPT) ---
+  // The Codex grid tell is two hairline `linear-gradient(... <color> 1px,
+  // transparent 1px)` layers (one per axis) tiled by a repeating
+  // `background-size` cell. Both signals must co-occur in the SAME style block
+  // (a CSS rule body or one inline `style="..."`): two hairline stops WITHOUT a
+  // tiling background-size is a fixed crosshair, not a grid, and a single
+  // hairline is a legitimate ruled line. Scoping to one block also stops
+  // unrelated single-axis rules on separate elements from adding up across the
+  // page. Count hairlines only inside `background`/`background-image` values so
+  // a hairline in an unrelated property (mask-image, border-image) can't stand
+  // in for the second axis. Colors like `oklch(96% 0.012 82 / 0.055)` carry
+  // nested parens, so match the hairline stop directly rather than parsing
+  // whole gradient layers.
+  {
+    const hairlineRe = /\b\d{1,3}px\s*,\s*transparent\s+\d{1,3}px/gi;
+    const gridSizeRe = /background-size\s*:[^;{}"']*\b\d{1,3}px\b/i;
+    const bgDeclRe = /\bbackground(?:-image)?\s*:\s*([^;{}"']*)/gi;
+    const blockRe = /\{([^{}]*)\}|style\s*=\s*"([^"]*)"|style\s*=\s*'([^']*)'/gi;
+    let blk;
+    while ((blk = blockRe.exec(html)) !== null) {
+      const block = blk[1] || blk[2] || blk[3] || '';
+      if (!gridSizeRe.test(block)) continue;
+      let hairlineCount = 0;
+      let bm;
+      bgDeclRe.lastIndex = 0;
+      while ((bm = bgDeclRe.exec(block)) !== null) {
+        const stops = bm[1].match(hairlineRe);
+        if (stops) hairlineCount += stops.length;
+      }
+      if (hairlineCount >= 2) {
+        findings.push({ id: 'codex-grid-background', snippet: 'two-axis grid-line gradient background' });
+        break;
+      }
+    }
+  }
+
   // --- Provider tells (gated): "X theater" framing copy (GPT) ---
   // Lives here (regex-on-HTML) rather than in the text-content analyzers so it
   // runs in the bundled browser path too, not just the CLI/static path.