diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index dc3b792d5..849105bb0 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,4 +1,4 @@
-name: "Test build"
+name: "Test and Build"
 
 on:
   push:
@@ -18,6 +18,27 @@ env:
   NODE_VERSION: 18
 
 jobs:
+  test:
+    name: Run tests
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          submodules: recursive
+
+      - name: Set up Node.js ${{ env.NODE_VERSION }}
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
+        with:
+          cache: yarn
+          node-version: ${{ env.NODE_VERSION }}
+
+      - name: Install dependencies
+        run: script/bootstrap
+
+      - name: Run tests
+        run: npx vitest run
+
   build_frontend:
     name: Test build
     runs-on: ubuntu-latest
diff --git a/src/tools/markdown.ts b/src/tools/markdown.ts
index 029a34811..5a6cf8683 100644
--- a/src/tools/markdown.ts
+++ b/src/tools/markdown.ts
@@ -31,12 +31,29 @@ export const markdownWithRepositoryContext = (input: string, repository?: Reposi
       return x.replace("(#", `(/hacs/repository/${repository.id}#`);
     });
 
-    // Add references to issues and PRs
-    input = input.replace(/(?:\w[\w-.]+\/\w[\w-.]+|\B)#[1-9]\d*\b/g, (reference) => {
-      const fullReference = reference.replace(/^#/, `${repository.full_name}#`);
-      const [fullName, issue] = fullReference.split("#");
-      return `[${reference}](https://github.com/${fullName}/issues/${issue})`;
-    });
+    // Add references to issues and PRs (avoid CSS hex colors and code blocks)
+    input = input.replace(
+      /(^|[\s])((?:\w[\w-.]+\/\w[\w-.]+)?#[1-9]\d*)\b/g,
+      (match, prefix, reference, offset) => {
+        const issueNumber = reference.split("#")[1];
+
+        // Skip if it's a valid CSS hex color (only contains 0-9a-f and is 3 or 6 digits)
+        if (issueNumber && /^[0-9a-fA-F]{3}$|^[0-9a-fA-F]{6}$/.test(issueNumber)) {
+          // Check if it's in a CSS context
+          if (/(?<=color:\s*|background:\s*|border:\s*|:\s*)$/.test(input.substring(0, offset))) {
+            return match;
+          }
+        }
+
+        const fullReference = reference.includes("/")
+          ? reference
+          : `${repository.full_name}${reference}`;
+        const [fullName, issue] = fullReference.split("#");
+        return fullName && issue
+          ? `${prefix}[${reference}](https://github.com/${fullName}/issues/${issue})`
+          : match;
+      },
+    );
   }
   return input;
 };
diff --git a/tests/markdown.test.ts b/tests/markdown.test.ts
new file mode 100644
index 000000000..8afe34038
--- /dev/null
+++ b/tests/markdown.test.ts
@@ -0,0 +1,127 @@
+import { describe, it, expect } from "vitest";
+import { markdownWithRepositoryContext } from "../src/tools/markdown.js";
+import type { RepositoryInfo } from "../src/data/repository.js";
+
+const mockRepository: RepositoryInfo = {
+  id: "123",
+  full_name: "awesome/repo",
+  default_branch: "main",
+  available_version: "v1.0.0",
+} as RepositoryInfo;
+
+describe("markdownWithRepositoryContext", () => {
+  it("should convert GitHub issue references to links", () => {
+    const input = "See issue #123 for details";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe("See issue [#123](https://github.com/awesome/repo/issues/123) for details");
+  });
+
+  it("should NOT convert CSS color codes", () => {
+    const input = "Set color: #123456 in your CSS";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe("Set color: #123456 in your CSS");
+  });
+
+  it("should NOT convert CSS shorthand colors", () => {
+    const input = "Use background:#123; border:#abc;";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe("Use background:#123; border:#abc;");
+  });
+
+  it("should handle mixed scenarios correctly", () => {
+    const input = "Fix issue #42 but keep color:#333 and border:#456 styles intact";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe(
+      "Fix issue [#42](https://github.com/awesome/repo/issues/42) but keep color:#333 and border:#456 styles intact",
+    );
+  });
+
+  it("should handle duplicate patterns correctly", () => {
+    const input = "Issue #123 was fixed. Later, set color: #123 in CSS. Then see #456.";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe(
+      "Issue [#123](https://github.com/awesome/repo/issues/123) was fixed. Later, set color: #123 in CSS. Then see [#456](https://github.com/awesome/repo/issues/456).",
+    );
+  });
+
+  it("should convert legitimate issue numbers but not hex colors", () => {
+    const input = "Issue #123 was fixed, but color: #456789 remains unchanged";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe(
+      "Issue [#123](https://github.com/awesome/repo/issues/123) was fixed, but color: #456789 remains unchanged",
+    );
+  });
+
+  it("should work without repository context", () => {
+    const input = "Some text with #123 reference";
+    const result = markdownWithRepositoryContext(input);
+    expect(result).toBe("Some text with #123 reference");
+  });
+
+  it("should NOT convert CSS hex colors in code examples", () => {
+    const input = "Example CSS: div { color:#ff0000; background:#123456; }";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe("Example CSS: div { color:#ff0000; background:#123456; }");
+  });
+
+  it("should handle repository/issue references correctly", () => {
+    const input = "Check out awesome/other-repo#456 for more info";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe(
+      "Check out [awesome/other-repo#456](https://github.com/awesome/other-repo/issues/456) for more info",
+    );
+  });
+
+  it("should handle issue numbers with 8 and 9 (non-hex digits)", () => {
+    const input = "See issues #789 and #98 for details";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe(
+      "See issues [#789](https://github.com/awesome/repo/issues/789) and [#98](https://github.com/awesome/repo/issues/98) for details",
+    );
+  });
+
+  it("should NOT convert 6-digit hex colors in CSS context", () => {
+    const input = "Apply color:#ffffff and background-color:#000000 styles";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe("Apply color:#ffffff and background-color:#000000 styles");
+  });
+
+  it("should convert valid issue numbers that contain non-hex digits", () => {
+    const input = "Fixed in #987 and resolved in #1289";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe(
+      "Fixed in [#987](https://github.com/awesome/repo/issues/987) and resolved in [#1289](https://github.com/awesome/repo/issues/1289)",
+    );
+  });
+
+  it("should handle mixed CSS and issue references in same text", () => {
+    const input = "Issue #789 fixed. Use border:#123; and see #890 too";
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    expect(result).toBe(
+      "Issue [#789](https://github.com/awesome/repo/issues/789) fixed. Use border:#123; and see [#890](https://github.com/awesome/repo/issues/890) too",
+    );
+  });
+  it("should handle large text efficiently", () => {
+    // Create a large string with mixed content to test performance
+    const parts: string[] = [];
+    for (let i = 0; i < 25_000; i++) {
+      parts.push(`Issue #${i + 1} was fixed. Use color:#${String(i).padStart(3, "0")}; in CSS.`);
+    }
+    const input = parts.join(" ");
+
+    const start = performance.now();
+    const result = markdownWithRepositoryContext(input, mockRepository);
+    const end = performance.now();
+
+    // Should complete in reasonable time (< 100ms for this test)
+    expect(end - start).toBeLessThan(100);
+
+    // Should have converted all issue references
+    expect(result).toContain("[#1](https://github.com/awesome/repo/issues/1)");
+    expect(result).toContain("[#25000](https://github.com/awesome/repo/issues/25000)");
+
+    // Should not have converted CSS colors
+    expect(result).toContain("color:#001;");
+    expect(result).toContain("color:#099;");
+  });
+});
diff --git a/vitest.config.ts b/vitest.config.ts
new file mode 100644
index 000000000..05a242924
--- /dev/null
+++ b/vitest.config.ts
@@ -0,0 +1,8 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    environment: "node",
+    include: ["tests/**/*.test.{js,ts}"],
+  },
+});