feat(workflows): implement workflow duplication feature

- Added functionality to duplicate workflows via a new API endpoint, allowing users to create copies of existing workflows with modified names and owners.
- Introduced utility functions for managing workflow filenames and ensuring unique names for duplicates.
- Created a user interface component for duplicating workflows, including validation for existing files and owner changes.
- Enhanced existing workflows to support the new duplication feature, ensuring seamless integration with the current workflow management system.

This update significantly improves user experience by enabling efficient workflow management and organization.

packages/server/src/api/workflows.js

@@ -10,6 +10,11 @@ import {
   authLabel,
   validateWorkflowHttpTriggers,
 } from "../../workflow-http-validate.js";
+import {
+  duplicateWorkflowYaml,
+  ensureWorkflowFilename,
+  suggestCopyFilename,
+} from "../../workflow-duplicate.js";
 
 function triggerSummary(owner, workflow) {
   if (!workflow || typeof workflow !== "object") return [];
@@ -259,6 +264,101 @@ export default function workflowsPluginFactory(registry) {
       return { ok: true };
     });
 
+    fastify.post("/workflows/:owner/:file/duplicate", async (req, reply) => {
+      const { owner, file } = /** @type {{ owner: string, file: string }} */ (
+        req.params
+      );
+      try {
+        fsStore.assertOwner(owner);
+        fsStore.assertWorkflowFile(file);
+      } catch (err) {
+        return reply.code(err.statusCode ?? 400).send({ error: err.message });
+      }
+      const source = fsStore.readWorkflowYaml(owner, file);
+      if (source == null) {
+        return reply.code(404).send({ error: "workflow not found" });
+      }
+
+      const body = /** @type {{ file?: unknown, owner?: unknown }} */ (req.body ?? {});
+      let destOwner = owner;
+      if (body.owner != null && body.owner !== "") {
+        if (typeof body.owner !== "string") {
+          return reply.code(400).send({ error: "owner must be a string" });
+        }
+        try {
+          destOwner = fsStore.assertOwner(body.owner);
+        } catch (err) {
+          return reply.code(err.statusCode ?? 400).send({ error: err.message });
+        }
+      }
+
+      let destFile;
+      try {
+        if (body.file == null || body.file === "") {
+          destFile = suggestCopyFilename(file, fsStore.listOwnerYamlFiles(destOwner));
+        } else if (typeof body.file !== "string") {
+          return reply.code(400).send({ error: "file must be a string" });
+        } else {
+          destFile = ensureWorkflowFilename(body.file);
+        }
+        fsStore.assertWorkflowFile(destFile);
+      } catch (err) {
+        return reply.code(err.statusCode ?? 400).send({ error: err.message });
+      }
+
+      if (destOwner === owner && destFile === file) {
+        return reply.code(400).send({ error: "cannot duplicate onto itself" });
+      }
+      if (fsStore.readWorkflowYaml(destOwner, destFile) != null) {
+        return reply.code(409).send({ error: "workflow already exists" });
+      }
+
+      let content;
+      try {
+        content = duplicateWorkflowYaml(source, {
+          sourceFile: file,
+          destFile,
+          rewriteHttpPaths: destOwner === owner,
+        });
+      } catch (err) {
+        return reply.code(err.statusCode ?? 400).send({
+          error: err instanceof Error ? err.message : String(err),
+        });
+      }
+
+      let parsed;
+      try {
+        parsed = yaml.parse(content);
+      } catch (err) {
+        return reply.code(400).send({
+          error: `invalid yaml: ${err instanceof Error ? err.message : String(err)}`,
+        });
+      }
+      try {
+        compileWorkflowScripts(parsed?.scripts);
+      } catch (err) {
+        return reply.code(400).send({
+          error: err instanceof Error ? err.message : String(err),
+        });
+      }
+      try {
+        await validateWorkflowHttpTriggers(parsed);
+      } catch (err) {
+        return reply.code(err.statusCode ?? 400).send({
+          error: err instanceof Error ? err.message : String(err),
+        });
+      }
+
+      fsStore.writeWorkflowYaml(destOwner, destFile, content);
+      const registered = fsStore.readRegisters(destOwner);
+      if (!registered.includes(destFile)) {
+        registered.push(destFile);
+        fsStore.writeRegisters(destOwner, registered);
+      }
+      registry.reregister();
+      return reply.code(201).send({ owner: destOwner, file: destFile });
+    });
+
     fastify.post("/workflows/:owner/:file/run", async (req, reply) => {
       const { owner, file } = /** @type {{ owner: string, file: string }} */ (
         req.params