Add llms.txt and llms-all.txt endpoints for LLM-friendly content

src/main/java/io/jenkins/plugins/designlibrary/Home.java

@@ -3,10 +3,14 @@
 import hudson.Extension;
 import hudson.PluginWrapper;
 import hudson.model.RootAction;
+import java.io.IOException;
+import java.io.PrintWriter;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ThreadLocalRandom;
 import jenkins.model.Jenkins;
+import org.kohsuke.stapler.StaplerRequest2;
+import org.kohsuke.stapler.StaplerResponse2;
 
 /**
  * Entry point to all the UI samples.
@@ -54,6 +58,42 @@
         return null;
     }
 
+    /**
+     * Serves LLM-friendly content as plain text markdown.
+     *
+     * <ul>
+     *   <li>{@code llms.txt} - index of all components</li>
+     *   <li>{@code llms-all.txt} - all component documentation in a single file</li>
+     * </ul>
+     */
+    public void doDynamic(StaplerRequest2 req, StaplerResponse2 rsp) throws IOException {
+        String restOfPath = req.getRestOfPath();
+        if (restOfPath.startsWith("/")) {
+            restOfPath = restOfPath.substring(1);
+        }
+
+        String content = resolveLlmContent(restOfPath, req);
+        if (content != null) {
+            rsp.setContentType("text/plain;charset=UTF-8");
+            try (PrintWriter w = rsp.getWriter()) {
+                w.write(content);
+            }
+            return;
+        }
+
+        rsp.sendError(404);
+    }
+
+    private String resolveLlmContent(String name, StaplerRequest2 req) {
+        if ("llms.txt".equals(name)) {
+            return LlmContent.generateIndex();
+        }
+        if ("llms-all.txt".equals(name)) {
+            return LlmContent.generateAll(req.getServletContext());
+        }
+        return null;
+    }
+
     public String getPluginVersion() {
         Jenkins jenkins = Jenkins.get();
         PluginWrapper plugin = jenkins.getPluginManager().getPlugin("design-library");

src/main/java/io/jenkins/plugins/designlibrary/LlmContent.java

@@ -0,0 +1,123 @@
+package io.jenkins.plugins.designlibrary;
+
+import jakarta.servlet.ServletContext;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import org.kohsuke.accmod.Restricted;
+import org.kohsuke.accmod.restrictions.NoExternalUse;
+
+@Restricted(NoExternalUse.class)
+class LlmContent {
+
+    private static final Pattern CODE_FILE_PATTERN = Pattern.compile("file=\"([^\"]+)\"");
+
+    private LlmContent() {}
+
+    static String generateIndex() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("# Jenkins Design Library\n\n");
+        sb.append("> A reference library of UI components and patterns ");
+        sb.append("for building Jenkins plugin interfaces.\n\n");
+
+        for (Map.Entry<Category, List<UISample>> entry : UISample.getGrouped().entrySet()) {
+            sb.append("## ").append(entry.getKey().getDisplayName()).append('\n');
+            for (UISample sample : entry.getValue()) {
+                sb.append("- ").append(sample.getDisplayName()).append(": ");
+                sb.append(sample.getDescription()).append('\n');
+            }
+            sb.append('\n');
+        }
+
+        return sb.toString();
+    }
+
+    static String generateAll(ServletContext context) {
+        StringBuilder sb = new StringBuilder();
+        sb.append("# Jenkins Design Library\n\n");
+        sb.append("> A reference library of UI components and patterns ");
+        sb.append("for building Jenkins plugin interfaces.\n\n");
+
+        for (Map.Entry<Category, List<UISample>> entry : UISample.getGrouped().entrySet()) {
+            sb.append("## ").append(entry.getKey().getDisplayName()).append("\n\n");
+            for (UISample sample : entry.getValue()) {
+                sb.append(generateComponentMarkdown(sample, context));
+                sb.append("\n---\n\n");
+            }
+        }
+
+        return sb.toString();
+    }
+
+    private static String generateComponentMarkdown(UISample sample, ServletContext context) {
+        StringBuilder sb = new StringBuilder();
+        sb.append("# ").append(sample.getDisplayName()).append("\n\n");
+        sb.append("> ").append(sample.getDescription()).append("\n\n");
+        sb.append("**Category:** ")
+                .append(sample.getCategory().getDisplayName())
+                .append('\n');
+
+        if (sample.getSince() != null) {
+            sb.append("**Since:** ").append(sample.getSince()).append('\n');
+        }
+        sb.append('\n');
+
+        String componentName = sample.getClass().getSimpleName();
+        List<String> snippetFiles = findSnippetReferences(sample);
+
+        for (String filename : snippetFiles) {
+            String path = "/" + componentName + "/" + filename;
+            String content = readResource(context, path);
+
+            if (content != null && !content.isBlank()) {
+                String label = filename.replaceFirst("\\.[^.]+$", "");
+                String language = filename.endsWith(".js") ? "javascript" : "xml";
+                sb.append("### ").append(label).append("\n\n");
+                sb.append("```").append(language).append('\n');
+                sb.append(content.strip()).append('\n');
+                sb.append("```\n\n");
+            }
+        }
+
+        return sb.toString();
+    }
+
+    private static List<String> findSnippetReferences(UISample sample) {
+        List<String> files = new ArrayList<>();
+        String jellyPath = sample.getClass().getName().replace('.', '/') + "/index.jelly";
+
+        try (InputStream is = sample.getClass().getClassLoader().getResourceAsStream(jellyPath)) {
+            if (is == null) {
+                return files;
+            }
+            String jelly = new String(is.readAllBytes(), StandardCharsets.UTF_8);
+            Matcher matcher = CODE_FILE_PATTERN.matcher(jelly);
+            while (matcher.find()) {
+                String file = matcher.group(1);
+                if (!files.contains(file)) {
+                    files.add(file);
+                }
+            }
+        } catch (IOException e) {
+            // skip
+        }
+
+        return files;
+    }
+
+    private static String readResource(ServletContext context, String path) {
+        try (InputStream is = context.getResourceAsStream(path)) {
+            if (is == null) {
+                return null;
+            }
+            return new String(is.readAllBytes(), StandardCharsets.UTF_8);
+        } catch (IOException e) {
+            return null;
+        }
+    }
+}

src/main/resources/io/jenkins/plugins/designlibrary/Home/index.jelly

@@ -51,6 +51,21 @@
             </div>
           </s:section>
 
+          <s:section title="${%integrate}">
+            <div class="app-home__side-by-side">
+              <s:card icon="symbol-intellij plugin-design-library"
+                      title="${%get-plugin}"
+                      description="${%get-plugin-description}"
+                      href="https://plugins.jetbrains.com/plugin/1885-jenkins-development-support"
+                      tag="${%Updated}" />
+              <s:card icon="symbol-sparkles-outline plugin-ionicons-api"
+                      title="${%use-with-ai}"
+                      description="${%use-with-ai-description}"
+                      href="llms.txt"
+                      tag="${%New}" />
+            </div>
+          </s:section>
+
           <s:section title="${%get-involved}">
             <div class="app-home__side-by-side">
               <s:card icon="symbol-gitter plugin-design-library"

src/main/resources/io/jenkins/plugins/designlibrary/Home/index.properties

@@ -14,3 +14,8 @@ gitter-description=Join the UX discussion on Gitter
 ux-youtube=Watch the latest Jenkins UX meetings
 ux-wip-core=View in-progress UX work
 contribute=Contribute to Jenkins Design Library
+integrate=Integrate with your workflow
+get-plugin=Get the IntelliJ plugin
+get-plugin-description=Jenkins development support for Jelly, Stapler, and Symbols autocompletion.
+use-with-ai=Use with AI
+use-with-ai-description=Provide structured design guidance to coding assistants, agents, and other LLM tools.

src/main/resources/scss/pages/_home.scss

@@ -22,7 +22,6 @@
   display: grid;
   grid-template-columns: 1fr 1fr;
   grid-gap: var(--jdl-spacing);
-  overflow: hidden;
 
   @media (max-width: 970px) {
     display: flex;

src/test/java/LlmContentTest.java

@@ -0,0 +1,57 @@
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.TestInstance.Lifecycle.PER_CLASS;
+
+import org.htmlunit.Page;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.junit.jupiter.WithJenkins;
+
+@WithJenkins
+@TestInstance(PER_CLASS)
+class LlmContentTest {
+
+    private JenkinsRule jenkins;
+
+    @BeforeAll
+    void beforeAll(JenkinsRule jenkins) {
+        this.jenkins = jenkins;
+    }
+
+    @Test
+    void llmsTxtContainsIndex() throws Exception {
+        try (var webClient = jenkins.createWebClient()) {
+            Page page = webClient.getPage(jenkins.getURL() + "design-library/llms.txt");
+            String content = page.getWebResponse().getContentAsString();
+
+            assertThat(content).startsWith("# Jenkins Design Library");
+            assertThat(content).contains("## Components");
+            assertThat(content).contains("## Patterns");
+            assertThat(content).contains("Buttons");
+        }
+    }
+
+    @Test
+    void llmsAllTxtContainsAllComponents() throws Exception {
+        try (var webClient = jenkins.createWebClient()) {
+            Page page = webClient.getPage(jenkins.getURL() + "design-library/llms-all.txt");
+            String content = page.getWebResponse().getContentAsString();
+
+            assertThat(content).startsWith("# Jenkins Design Library");
+            assertThat(content).contains("# Buttons");
+            assertThat(content).contains("# Cards");
+            assertThat(content).contains("# Colors");
+        }
+    }
+
+    @Test
+    void existingComponentPagesStillWork() throws Exception {
+        try (var webClient = jenkins.createWebClient().withJavaScriptEnabled(false)) {
+            webClient.getOptions().setThrowExceptionOnFailingStatusCode(false);
+            webClient.getOptions().setPrintContentOnFailingStatusCode(false);
+            Page page = webClient.getPage(jenkins.getURL() + "design-library/buttons");
+            assertThat(page.getWebResponse().getStatusCode()).isEqualTo(200);
+        }
+    }
+}

src/test/java/ValidRelativeUrlsTest.java

@@ -2,7 +2,6 @@
 import static org.junit.jupiter.api.TestInstance.Lifecycle.PER_CLASS;
 
 import io.jenkins.plugins.designlibrary.UISample;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.stream.Stream;
 import org.htmlunit.html.DomNode;
@@ -22,6 +21,8 @@ class ValidRelativeUrlsTest {
 
     private List<UISample> samples;
 
+    private final List<String> otherUrls = List.of("llms.txt");
+
     @BeforeAll
     void beforeAll(JenkinsRule jenkins) {
         this.jenkins = jenkins;
@@ -39,8 +40,8 @@ void validRelativeUrls(String url) throws Exception {
             webClient.getOptions().setPrintContentOnFailingStatusCode(false);
             webClient.getOptions().setThrowExceptionOnFailingStatusCode(false);
 
-            List<String> validUrls =
-                    new ArrayList<>(samples.stream().map(UISample::getUrlName).toList());
+            List<String> validUrls = Stream.concat(samples.stream().map(UISample::getUrlName), otherUrls.stream())
+                    .toList();
 
             var page = webClient.goTo(url);
             var links = page.querySelectorAll(".jdl-section a");