Add modernization workflow canvas (#2758)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-09-16 11:51:03 +00:00 · 2026-09-14 14:29:03 +10:00
parent 7568a482ce
commit 5e59c61ead
12 changed files with 799 additions and 0 deletions
@@ -0,0 +1,104 @@
+import { randomBytes } from "node:crypto";
+import { createServer } from "node:http";
+import { getWorkflowState } from "./state.mjs";
+import { renderHtml } from "./renderer.mjs";
+
+function sendJson(res, status, value) {
+    res.writeHead(status, {
+        "Content-Type": "application/json; charset=utf-8",
+        "Cache-Control": "no-store",
+    });
+    res.end(JSON.stringify(value));
+}
+
+async function readJson(req) {
+    const chunks = [];
+    let size = 0;
+    for await (const chunk of req) {
+        size += chunk.length;
+        if (size > 64 * 1024) throw new Error("Request body is too large.");
+        chunks.push(chunk);
+    }
+    return chunks.length ? JSON.parse(Buffer.concat(chunks).toString("utf8")) : {};
+}
+
+export async function pushState(rec, state) {
+    const payload = `event: state\ndata: ${JSON.stringify(state)}\n\n`;
+    for (const client of rec.clients) client.write(payload);
+}
+
+export async function createInstanceServer(options) {
+    const token = randomBytes(24).toString("hex");
+    const clients = new Set();
+    let rec;
+
+    const server = createServer(async (req, res) => {
+        const url = new URL(req.url, "http://127.0.0.1");
+        try {
+            if (req.method === "GET" && url.pathname === "/") {
+                const state = await getWorkflowState(options.workspace, options.stateId);
+                res.writeHead(200, {
+                    "Content-Type": "text/html; charset=utf-8",
+                    "Cache-Control": "no-store",
+                    "Content-Security-Policy": "default-src 'self'; style-src 'unsafe-inline'; script-src 'unsafe-inline'; connect-src 'self'; img-src 'self' data:",
+                    "X-Content-Type-Options": "nosniff",
+                    "Referrer-Policy": "no-referrer",
+                });
+                res.end(renderHtml(state, token));
+                return;
+            }
+
+            if (req.method === "GET" && url.pathname === "/events") {
+                res.writeHead(200, {
+                    "Content-Type": "text/event-stream",
+                    "Cache-Control": "no-cache",
+                    Connection: "keep-alive",
+                });
+                clients.add(res);
+                req.on("close", () => clients.delete(res));
+                return;
+            }
+
+            if (req.method !== "POST" || req.headers["x-canvas-token"] !== token) {
+                sendJson(res, 403, { error: "Request rejected." });
+                return;
+            }
+
+            const input = await readJson(req);
+            let state;
+            if (url.pathname === "/api/configure") {
+                state = await options.onConfigure(input);
+            } else if (url.pathname === "/api/step") {
+                state = await options.onSetStep(input.step, input.status);
+            } else if (url.pathname === "/api/refresh") {
+                state = await options.onRefresh();
+            } else {
+                sendJson(res, 404, { error: "Not found." });
+                return;
+            }
+
+            await pushState(rec, state);
+            sendJson(res, 200, state);
+        } catch (error) {
+            sendJson(res, 400, { error: error instanceof Error ? error.message : String(error) });
+        }
+    });
+
+    await new Promise((resolve, reject) => {
+        server.once("error", reject);
+        server.listen(0, "127.0.0.1", resolve);
+    });
+    const address = server.address();
+    rec = {
+        ...options,
+        server,
+        clients,
+        url: `http://127.0.0.1:${address.port}/`,
+    };
+
+    if (Object.keys(options.initialConfig).some((key) =>
+        ["language", "source", "goal", "planName"].includes(key))) {
+        await options.onConfigure(options.initialConfig);
+    }
+    return rec;
+}