feat: add WorkflowBrowserView component for browsing saved workflows

Reusable component with two states: empty state prompting user to choose
a workflows folder, and listing state showing all workflows with name,
node count, and relative time. Supports changing folder and one-off browsing.

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

src/components/quickstart/WorkflowBrowserView.tsx

@@ -0,0 +1,322 @@
+"use client";
+
+import { useState, useEffect, useCallback } from "react";
+import { WorkflowFile } from "@/store/workflowStore";
+import { QuickstartBackButton } from "./QuickstartBackButton";
+import {
+  getWorkflowsDirectory,
+  setWorkflowsDirectory,
+} from "@/store/utils/localStorage";
+
+interface WorkflowListEntry {
+  name: string;
+  directoryPath: string;
+  nodeCount: number;
+  lastModified: number;
+}
+
+interface WorkflowBrowserViewProps {
+  onBack?: () => void;
+  onWorkflowLoaded: (workflow: WorkflowFile, directoryPath: string) => void;
+  onClose?: () => void;
+}
+
+function formatRelativeTime(timestamp: number): string {
+  const seconds = Math.floor((Date.now() - timestamp) / 1000);
+  if (seconds < 60) return "just now";
+  const minutes = Math.floor(seconds / 60);
+  if (minutes < 60) return `${minutes}m ago`;
+  const hours = Math.floor(minutes / 60);
+  if (hours < 24) return `${hours}h ago`;
+  const days = Math.floor(hours / 24);
+  if (days < 30) return `${days}d ago`;
+  const months = Math.floor(days / 30);
+  return `${months}mo ago`;
+}
+
+export function WorkflowBrowserView({
+  onBack,
+  onWorkflowLoaded,
+  onClose,
+}: WorkflowBrowserViewProps) {
+  const [defaultDir, setDefaultDir] = useState<string | null>(null);
+  const [workflows, setWorkflows] = useState<WorkflowListEntry[]>([]);
+  const [isLoading, setIsLoading] = useState(false);
+  const [loadingWorkflow, setLoadingWorkflow] = useState<string | null>(null);
+  const [error, setError] = useState<string | null>(null);
+
+  useEffect(() => {
+    setDefaultDir(getWorkflowsDirectory());
+  }, []);
+
+  const fetchWorkflows = useCallback(async (dirPath: string) => {
+    setIsLoading(true);
+    setError(null);
+    try {
+      const res = await fetch(
+        `/api/list-workflows?path=${encodeURIComponent(dirPath)}`
+      );
+      const result = await res.json();
+      if (result.success) {
+        setWorkflows(result.workflows);
+        if (result.workflows.length === 0) {
+          setError("No workflows found in this folder");
+        }
+      } else {
+        setError(result.error || "Failed to list workflows");
+      }
+    } catch {
+      setError("Failed to fetch workflows");
+    } finally {
+      setIsLoading(false);
+    }
+  }, []);
+
+  // Fetch workflows when default directory is set
+  useEffect(() => {
+    if (defaultDir) {
+      fetchWorkflows(defaultDir);
+    }
+  }, [defaultDir, fetchWorkflows]);
+
+  const handleChooseFolder = useCallback(async () => {
+    try {
+      const res = await fetch("/api/browse-directory");
+      const result = await res.json();
+      if (result.success && !result.cancelled && result.path) {
+        setWorkflowsDirectory(result.path);
+        setDefaultDir(result.path);
+      }
+    } catch {
+      setError("Failed to open directory picker");
+    }
+  }, []);
+
+  const handleChangeFolder = useCallback(async () => {
+    try {
+      const res = await fetch("/api/browse-directory");
+      const result = await res.json();
+      if (result.success && !result.cancelled && result.path) {
+        setWorkflowsDirectory(result.path);
+        setDefaultDir(result.path);
+      }
+    } catch {
+      setError("Failed to open directory picker");
+    }
+  }, []);
+
+  const handleBrowseOther = useCallback(async () => {
+    try {
+      const browseRes = await fetch("/api/browse-directory");
+      const browseResult = await browseRes.json();
+
+      if (
+        !browseResult.success ||
+        browseResult.cancelled ||
+        !browseResult.path
+      ) {
+        if (!browseResult.success && !browseResult.cancelled) {
+          setError(browseResult.error || "Failed to open directory picker");
+        }
+        return;
+      }
+
+      const dirPath = browseResult.path;
+
+      setLoadingWorkflow(dirPath);
+      const loadRes = await fetch(
+        `/api/workflow?path=${encodeURIComponent(dirPath)}&load=true`
+      );
+      const loadResult = await loadRes.json();
+      setLoadingWorkflow(null);
+
+      if (!loadResult.success) {
+        setError(loadResult.error || "No workflow file found in directory");
+        return;
+      }
+
+      onWorkflowLoaded(loadResult.workflow as WorkflowFile, dirPath);
+      onClose?.();
+    } catch {
+      setLoadingWorkflow(null);
+      setError("Failed to open workflow");
+    }
+  }, [onWorkflowLoaded, onClose]);
+
+  const handleSelectWorkflow = useCallback(
+    async (entry: WorkflowListEntry) => {
+      setLoadingWorkflow(entry.directoryPath);
+      setError(null);
+      try {
+        const res = await fetch(
+          `/api/workflow?path=${encodeURIComponent(entry.directoryPath)}&load=true`
+        );
+        const result = await res.json();
+
+        if (!result.success) {
+          setError(result.error || "Failed to load workflow");
+          setLoadingWorkflow(null);
+          return;
+        }
+
+        onWorkflowLoaded(
+          result.workflow as WorkflowFile,
+          entry.directoryPath
+        );
+        onClose?.();
+      } catch {
+        setError("Failed to load workflow");
+        setLoadingWorkflow(null);
+      }
+    },
+    [onWorkflowLoaded, onClose]
+  );
+
+  // State A: No default directory configured
+  if (defaultDir === null) {
+    return (
+      <div className="p-8 flex flex-col items-center">
+        {onBack && (
+          <div className="w-full mb-4">
+            <QuickstartBackButton onClick={onBack} />
+          </div>
+        )}
+        <div className="flex flex-col items-center gap-4 py-8">
+          <div className="w-12 h-12 rounded-xl bg-neutral-700/50 flex items-center justify-center">
+            <svg
+              className="w-6 h-6 text-neutral-400"
+              fill="none"
+              viewBox="0 0 24 24"
+              stroke="currentColor"
+              strokeWidth={1.5}
+            >
+              <path
+                strokeLinecap="round"
+                strokeLinejoin="round"
+                d="M2.25 12.75V12A2.25 2.25 0 014.5 9.75h15A2.25 2.25 0 0121.75 12v.75m-8.69-6.44l-2.12-2.12a1.5 1.5 0 00-1.061-.44H4.5A2.25 2.25 0 002.25 6v12a2.25 2.25 0 002.25 2.25h15A2.25 2.25 0 0021.75 18V9a2.25 2.25 0 00-2.25-2.25h-5.379a1.5 1.5 0 01-1.06-.44z"
+              />
+            </svg>
+          </div>
+          <div className="text-center">
+            <h2 className="text-lg font-medium text-neutral-200 mb-1">
+              Your Workflows
+            </h2>
+            <p className="text-sm text-neutral-500 max-w-xs">
+              Choose a folder that contains your workflow projects
+            </p>
+          </div>
+          <button
+            onClick={handleChooseFolder}
+            className="px-4 py-2 text-sm font-medium text-neutral-200 bg-neutral-700 hover:bg-neutral-600 rounded-lg transition-colors"
+          >
+            Choose folder
+          </button>
+        </div>
+      </div>
+    );
+  }
+
+  // State B: Default directory configured — show listing
+  return (
+    <div className="flex flex-col h-full max-h-[70vh]">
+      {/* Header */}
+      <div className="px-6 py-4 border-b border-neutral-700/50 flex-shrink-0">
+        <div className="flex items-center gap-3">
+          {onBack && <QuickstartBackButton onClick={onBack} />}
+          <div className="flex-1 min-w-0">
+            <h2 className="text-lg font-medium text-neutral-200">
+              Your Workflows
+            </h2>
+            <p
+              className="text-xs text-neutral-500 truncate"
+              title={defaultDir}
+            >
+              {defaultDir}
+            </p>
+          </div>
+        </div>
+      </div>
+
+      {/* Workflow list */}
+      <div className="flex-1 overflow-y-auto px-6 py-3">
+        {isLoading ? (
+          <div className="flex items-center justify-center py-12">
+            <div className="w-5 h-5 border-2 border-neutral-600 border-t-neutral-300 rounded-full animate-spin" />
+          </div>
+        ) : error && workflows.length === 0 ? (
+          <div className="flex flex-col items-center justify-center py-12 text-center">
+            <p className="text-sm text-neutral-500">{error}</p>
+          </div>
+        ) : (
+          <div className="flex flex-col gap-1">
+            {workflows.map((entry) => (
+              <button
+                key={entry.directoryPath}
+                onClick={() => handleSelectWorkflow(entry)}
+                disabled={loadingWorkflow !== null}
+                className="group text-left px-4 py-3 rounded-lg hover:bg-neutral-700/40 transition-colors disabled:opacity-50"
+              >
+                <div className="flex items-center justify-between">
+                  <div className="min-w-0 flex-1">
+                    <span className="text-sm font-medium text-neutral-200 group-hover:text-neutral-100 transition-colors">
+                      {entry.name}
+                    </span>
+                    <div className="flex items-center gap-2 mt-0.5">
+                      <span className="text-xs text-neutral-500">
+                        {entry.nodeCount} node{entry.nodeCount !== 1 ? "s" : ""}
+                      </span>
+                      <span className="text-neutral-700">·</span>
+                      <span className="text-xs text-neutral-500">
+                        {formatRelativeTime(entry.lastModified)}
+                      </span>
+                    </div>
+                  </div>
+                  {loadingWorkflow === entry.directoryPath ? (
+                    <div className="w-4 h-4 border-2 border-neutral-600 border-t-neutral-300 rounded-full animate-spin" />
+                  ) : (
+                    <svg
+                      className="w-4 h-4 text-neutral-600 group-hover:text-neutral-400 transition-colors"
+                      fill="none"
+                      viewBox="0 0 24 24"
+                      stroke="currentColor"
+                      strokeWidth={2}
+                    >
+                      <path
+                        strokeLinecap="round"
+                        strokeLinejoin="round"
+                        d="M8.25 4.5l7.5 7.5-7.5 7.5"
+                      />
+                    </svg>
+                  )}
+                </div>
+              </button>
+            ))}
+          </div>
+        )}
+
+        {error && workflows.length > 0 && (
+          <p className="text-xs text-red-400 mt-2 px-4">{error}</p>
+        )}
+      </div>
+
+      {/* Footer */}
+      <div className="px-6 py-3 border-t border-neutral-700/50 flex-shrink-0 flex items-center gap-3">
+        <button
+          onClick={handleBrowseOther}
+          disabled={loadingWorkflow !== null}
+          className="text-xs text-neutral-400 hover:text-neutral-200 transition-colors disabled:opacity-50"
+        >
+          Browse other location...
+        </button>
+        <span className="text-neutral-700">·</span>
+        <button
+          onClick={handleChangeFolder}
+          disabled={loadingWorkflow !== null}
+          className="text-xs text-neutral-400 hover:text-neutral-200 transition-colors disabled:opacity-50"
+        >
+          Change folder
+        </button>
+      </div>
+    </div>
+  );
+}