Add collapsible code blocks and run workflow button to workflow detail

Code blocks are now expandable/collapsible with a chevron toggle, line
count, and LOC count in the header. TOML defaults collapsed, DOT
expanded. Workflow detail header gets a circular play button and
max-w-prose on the description for readability.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/arc-web/app/routes/workflow-definition.tsx

@@ -1,3 +1,4 @@
+import { ChevronRightIcon } from "@heroicons/react/20/solid";
 import { useEffect, useRef, useState } from "react";
 import { useParams } from "react-router";
 import { workflowData } from "./workflow-detail";
@@ -7,13 +8,16 @@ function CodeBlock({
   code,
   lang,
   filename,
+  defaultOpen = true,
 }: {
   code: string;
   lang: string;
   filename: string;
+  defaultOpen?: boolean;
 }) {
   const containerRef = useRef<HTMLDivElement>(null);
   const [ready, setReady] = useState(false);
+  const [open, setOpen] = useState(defaultOpen);
 
   useEffect(() => {
     let cancelled = false;
@@ -45,22 +49,39 @@ function CodeBlock({
     };
   }, [code, lang]);
 
+  const lines = code.split("\n");
+  const lineCount = lines.length;
+  const loc = lines.filter((l) => l.trim().length > 0).length;
+
   return (
     <div className="rounded-lg border border-white/[0.06] bg-navy-800/50 overflow-hidden">
-      <div className="flex items-center gap-2 border-b border-white/[0.06] px-4 py-2.5">
+      <button
+        type="button"
+        onClick={() => setOpen((v) => !v)}
+        className="flex w-full items-center gap-2 px-4 py-2.5 text-left hover:bg-white/[0.02] transition-colors"
+      >
+        <ChevronRightIcon
+          className={`size-4 text-navy-600 transition-transform duration-150 ${open ? "rotate-90" : ""}`}
+        />
         <span className="font-mono text-xs text-navy-600">{filename}</span>
+        <span className="ml-auto font-mono text-xs text-navy-600/60">
+          {lineCount} lines ({loc} loc)
+        </span>
+      </button>
+
+      <div className={open ? "" : "hidden"}>
+        <div className="border-t border-white/[0.06]" />
+        <div
+          ref={containerRef}
+          className={`shiki-container overflow-x-auto transition-opacity duration-200 ${ready ? "opacity-100" : "opacity-0"}`}
+        />
+
+        {!ready && (
+          <pre className="px-4 py-4 font-mono text-sm leading-relaxed text-navy-600">
+            {code}
+          </pre>
+        )}
       </div>
-
-      <div
-        ref={containerRef}
-        className={`shiki-container overflow-x-auto transition-opacity duration-200 ${ready ? "opacity-100" : "opacity-0"}`}
-      />
-
-      {!ready && (
-        <pre className="px-4 py-4 font-mono text-sm leading-relaxed text-navy-600">
-          {code}
-        </pre>
-      )}
     </div>
   );
 }
@@ -75,7 +96,7 @@ export default function WorkflowDefinition() {
 
   return (
     <div className="flex flex-col gap-6">
-      <CodeBlock code={workflow.config} lang="toml" filename="task.toml" />
+      <CodeBlock code={workflow.config} lang="toml" filename="task.toml" defaultOpen={false} />
       <CodeBlock code={workflow.graph} lang="dot" filename={workflow.filename} />
     </div>
   );

apps/arc-web/app/routes/workflow-detail.tsx

@@ -275,12 +275,23 @@ export default function WorkflowDetail() {
 
   return (
     <div>
-      <div className="mb-6">
-        <div className="flex items-center gap-3">
-          <h2 className="text-xl font-semibold text-white">{workflow.title}</h2>
-          <span className="font-mono text-xs text-navy-600">{workflow.filename}</span>
+      <div className="mb-6 flex items-center gap-4">
+        <div className="min-w-0 flex-1">
+          <div className="flex items-center gap-3">
+            <h2 className="text-xl font-semibold text-white">{workflow.title}</h2>
+            <span className="font-mono text-xs text-navy-600">{workflow.filename}</span>
+          </div>
+          <p className="mt-2 max-w-prose text-sm leading-relaxed text-ice-300">{workflow.description}</p>
         </div>
-        <p className="mt-2 text-sm leading-relaxed text-ice-300">{workflow.description}</p>
+        <button
+          type="button"
+          title="Run workflow"
+          className="flex size-9 shrink-0 items-center justify-center rounded-full border border-mint/20 text-mint transition-colors hover:border-mint/50 hover:bg-mint/10 hover:text-white"
+        >
+          <svg viewBox="0 0 24 24" fill="currentColor" className="size-4" aria-hidden="true">
+            <path fillRule="evenodd" d="M4.5 5.653c0-1.427 1.529-2.33 2.779-1.643l11.54 6.347c1.295.712 1.295 2.573 0 3.286L7.28 19.99c-1.25.687-2.779-.217-2.779-1.643V5.653Z" clipRule="evenodd" />
+          </svg>
+        </button>
       </div>
 
       <div className="border-b border-white/[0.06]">