Handle _.context syntax/import failures without crashing startup

.changeset/free-numbers-relate.md

@@ -0,0 +1,5 @@
+---
+"counterfact": patch
+---
+
+Warn and skip loading context modules when they fail to import, including syntax errors in \_.context files.

docs/features/state.md

@@ -38,6 +38,8 @@ export class Context {
 
 > [!IMPORTANT]
 > Keep context in memory. Counterfact is a development tool — starting fresh each time is a feature, not a bug. In-memory state also makes the server very fast.
+>
+> If a `_.context.ts` file has a syntax/import error, Counterfact prints a warning and skips loading that context file so the app keeps running.
 
 ## Nested contexts
 

src/server/module-loader.ts

@@ -302,6 +302,16 @@ export class ModuleLoader extends EventTarget {
           unescapePathForWindows(pathName),
         );
 
+        if (this.isContextFile(pathName)) {
+          const warning = isSyntaxError
+            ? `Warning: There is a syntax error in the context file: ${displayPath}`
+            : `Warning: There was an error loading the context file: ${displayPath}`;
+
+          process.stdout.write(`\n${warning}\n`);
+
+          return;
+        }
+
         const message = isSyntaxError
           ? `There is a syntax error in the route file: ${displayPath}`
           : `There was an error loading the route file: ${displayPath}`;

test/server/module-loader.test.ts

@@ -1,6 +1,7 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import { once } from "node:events";
 
+import { jest } from "@jest/globals";
 import { usingTemporaryFiles } from "using-temporary-files";
 
 import { ContextRegistry } from "../../src/server/context-registry.js";
@@ -365,6 +366,45 @@ describe("a module loader", () => {
       expect(response?.body).toContain("syntax error");
     });
   });
+
+  it("prints a warning and skips loading a context file with a syntax error", async () => {
+    await usingTemporaryFiles(async ($) => {
+      await $.add("_.context.js", "this is not valid javascript @@@");
+      await $.add(
+        "hello.js",
+        'export function GET() { return { body: "hello" }; }',
+      );
+      await $.add("package.json", '{ "type": "module" }');
+
+      const registry: Registry = new Registry();
+      const contextRegistry: ContextRegistry = new ContextRegistry();
+      const loader: ModuleLoader = new ModuleLoader(
+        $.path(""),
+        registry,
+        contextRegistry,
+      );
+
+      const stdoutSpy = jest
+        .spyOn(process.stdout, "write")
+        .mockImplementation((() => true) as any);
+
+      await expect(loader.load()).resolves.toBeUndefined();
+
+      expect(registry.exists("GET", "/hello")).toBe(true);
+      expect(contextRegistry.getAllPaths()).toEqual(["/"]);
+      expect(stdoutSpy).toHaveBeenCalledWith(
+        expect.stringContaining(
+          "Warning: There was an error loading the context file:",
+        ),
+      );
+      expect(stdoutSpy).toHaveBeenCalledWith(
+        expect.stringContaining("_.context.js"),
+      );
+      expect(stdoutSpy).toHaveBeenCalledTimes(1);
+
+      stdoutSpy.mockRestore();
+    });
+  });
 });
 
 describe("ModuleLoader scenario loading", () => {