接续L4-TOOL-DB浏览器Provider协议

结论：浏览器 Worker 已支持可插拔 Python runtime provider 的 line I/O，缺真实 Python/WASM runtime 时仍保持阻塞不解锁。

wasm-port/runtime/sdk/README.md

@@ -577,7 +577,9 @@ private module paths:
   boundary. The bundled worker reports
   `blocked_browser_python_wasm_runtime_missing` until a real Python/WASM runtime
   is installed; the Worker shell alone must not mark `DB_PROGRAM` execution
-  ready.
+  ready. The Worker supports a provider protocol (`start`, `writeLine`,
+  `readLine`, `close`) so a future Python/WASM runtime can provide line-based
+  `DB_PROGRAM` I/O without changing `ToolDbProcessPort`.
 - `createLinuxCncToolDbNodeRuntimeAdapter()` in
   `runtime/sdk/src/tool-db-node-runtime-adapter.js` for Node/native verification
   of the real LinuxCNC `DB_PROGRAM` child process. This adapter is intentionally

wasm-port/runtime/sdk/src/tool-db-browser-worker-adapter.js

@@ -96,7 +96,14 @@ export function createLinuxCncToolDbBrowserWorkerAdapter({
       return result.line;
     },
 
-    close() {
+    async close() {
+      if (worker) {
+        try {
+          await request("close");
+        } catch {
+          // The worker may be blocked or already gone; termination below is authoritative.
+        }
+      }
       rejectPending(new Error("Tool DB browser worker closed."));
       worker?.terminate();
       worker = null;

wasm-port/runtime/workers/tool-db-python-worker.js

@@ -15,12 +15,21 @@ function pythonRuntimeAvailable() {
   return typeof self.loadPyodide === "function" || Boolean(self.pyodide?.runPythonAsync);
 }
 
+function getRuntimeProvider() {
+  return self.linuxCncToolDbPythonRuntimeProvider ?? null;
+}
+
 self.addEventListener("message", async (event) => {
   const message = event.data ?? {};
-  const { id, type } = message;
+  const { id, type, line } = message;
   try {
     if (type === "start") {
-      const ready = pythonRuntimeAvailable();
+      const provider = getRuntimeProvider();
+      const providerReady = Boolean(provider?.start && provider?.writeLine && provider?.readLine);
+      const ready = providerReady || pythonRuntimeAvailable();
+      if (providerReady) {
+        await provider.start(message);
+      }
       postReply(id, type, {
         runtimeMode: "browser-python-wasm-worker",
         runtimeExecutionReady: ready,
@@ -32,6 +41,25 @@ self.addEventListener("message", async (event) => {
       });
       return;
     }
+    const provider = getRuntimeProvider();
+    if (type === "writeLine" && provider?.writeLine) {
+      await provider.writeLine(line);
+      postReply(id, type, { executionEnabled: false, promotionAllowed: false });
+      return;
+    }
+    if (type === "readLine" && provider?.readLine) {
+      postReply(id, type, {
+        line: await provider.readLine(),
+        executionEnabled: false,
+        promotionAllowed: false,
+      });
+      return;
+    }
+    if (type === "close" && provider?.close) {
+      await provider.close();
+      postReply(id, type, { executionEnabled: false, promotionAllowed: false });
+      return;
+    }
     throw new Error("blocked_browser_python_wasm_runtime_missing");
   } catch (error) {
     postError(id, type, error);