Commit 1e5f62801b7c4d247247bc3648310a20560e5b43 | the-knife

author	Julius Marminge <julius0216@outlook.com> 2026-06-20 11:20:14-07:00
committer	GitHub <noreply@github.com> 2026-06-20 11:20:14-07:00
log	1e5f62801b7c4d247247bc3648310a20560e5b43
tree	a87bc85d72ad9f8943dd9f0bc4fe4b7fa9c730b0
parent	ed6ba7439d55b8c2cf7324d5107c2c1cb3ee0920
signature	Signed by PGP key B5690EEEBB952194

[codex] Structure MCP snapshot failures (#3423)

Co-authored-by: codex <codex@users.noreply.github.com>

2 files changed, 103 insertions(+), 18 deletions(-)

apps
- server
  - src
    mcp
    McpHttpServer.test.ts
    McpHttpServer.ts

apps/server/src/mcp/McpHttpServer.test.ts+56

...	@@ -49,6 +49,62 @@ it("normalizes empty successful notification responses to accepted", () => {	...	@@ -49,6 +49,62 @@ it("normalizes empty successful notification responses to accepted", () => {
49	expect(resultResponse.status).toBe(200);	49	expect(resultResponse.status).toBe(200);
50	});	50	});
51		51
		52	it.effect("returns bounded structural preview snapshot failures", () =>
		53	Effect.scoped(
		54	Effect.gen(function* () {
		55	const server = yield* McpServer.McpServer;
		56	const broker = yield* PreviewAutomationBroker.PreviewAutomationBroker;
		57	const requests = yield* broker.connect({
		58	clientId: "mcp-failure-client",
		59	environmentId,
		60	threadId,
		61	tabId,
		62	visible: true,
		63	supportsAutomation: true,
		64	focusedAt: "2026-06-11T00:00:00.000Z",
		65	});
		66	yield* Stream.runForEach(requests, (request) =>
		67	broker.respond({
		68	requestId: request.requestId,
		69	ok: false,
		70	error: {
		71	_tag: "PreviewAutomationExecutionError",
		72	message: "sensitive renderer failure",
		73	detail: { consoleOutput: "sensitive browser output" },
		74	},
		75	}),
		76	).pipe(Effect.forkScoped);
		77	yield* Effect.yieldNow;
		78	yield* broker.reportOwner({
		79	clientId: "mcp-failure-client",
		80	environmentId,
		81	threadId,
		82	tabId,
		83	visible: true,
		84	supportsAutomation: true,
		85	focusedAt: "2026-06-11T00:00:00.000Z",
		86	});
		87
		88	const snapshot = yield* server
		89	.callTool({ name: "preview_snapshot", arguments: {} })
		90	.pipe(
		91	Effect.provideService(McpInvocationContext.McpInvocationContext, invocation),
		92	Effect.provideService(McpSchema.McpServerClient, client),
		93	);
		94
		95	expect(snapshot.isError).toBe(true);
		96	expect(snapshot.content).toEqual([{ type: "text", text: "Preview snapshot failed." }]);
		97	expect(snapshot.structuredContent).toEqual({
		98	error: {
		99	_tag: "PreviewAutomationExecutionError",
		100	operation: "snapshot",
		101	failureCount: 1,
		102	},
		103	});
		104	}),
		105	).pipe(Effect.provide(TestLayer)),
		106	);
		107
52	it.effect("terminates HTTP MCP sessions with DELETE", () =>	108	it.effect("terminates HTTP MCP sessions with DELETE", () =>
53	Effect.scoped(	109	Effect.scoped(
54	Effect.gen(function* () {	110	Effect.gen(function* () {

apps/server/src/mcp/McpHttpServer.ts+47-18

 @@ -88,6 +88,37 @@ const McpAuthMiddlewareLive = HttpRouter.middleware<{
   provides: McpInvocationContext.McpInvocationContext;
 }>()(makeMcpAuthMiddleware).layer;
+const previewSnapshotFailure = <E>(cause: Cause.Cause<E>) => {
+  if (Cause.hasInterrupts(cause) || cause.reasons.some(Cause.isDieReason)) {
+    return Effect.failCause(cause).pipe(Effect.orDie);
+  }
+  const failures = cause.reasons.filter(Cause.isFailReason);
+  const firstFailure = failures[0]?.error;
+  const errorTag =
+    typeof firstFailure === "object" &&
+    firstFailure !== null &&
+    "_tag" in firstFailure &&
+    typeof firstFailure._tag === "string"
+      ? firstFailure._tag
+      : "PreviewSnapshotError";
+  const result = new McpSchema.CallToolResult({
+    isError: true,
+    structuredContent: {
+      error: {
+        _tag: errorTag,
+        operation: "snapshot",
+        failureCount: failures.length,
+      },
+    },
+    content: [{ type: "text", text: "Preview snapshot failed." }],
+  });
+  return Effect.logWarning("preview snapshot failed", {
+    operation: "snapshot",
+    errorTag,
+    failureCount: failures.length,
+  }).pipe(Effect.as(result));
+};
 const registerPreviewSnapshot = Effect.fn("McpHttpServer.registerPreviewSnapshot")(function* () {
   const server = yield* McpServer.McpServer;
   const broker = yield* PreviewAutomationBroker.PreviewAutomationBroker;
 @@ -122,12 +153,8 @@ const registerPreviewSnapshot = Effect.fn("McpHttpServer.registerPreviewSnapshot
           Effect.flatMap(Effect.fromOption),
           Effect.provideService(PreviewAutomationBroker.PreviewAutomationBroker, broker),
           Effect.provideService(McpInvocationContext.McpInvocationContext, invocation),
-          Effect.matchCause({
+          Effect.matchCauseEffect({
-            onFailure: (cause) =>
+            onFailure: previewSnapshotFailure,
-              new McpSchema.CallToolResult({
-                isError: true,
-                content: [{ type: "text", text: Cause.pretty(cause) }],
-              }),
             onSuccess: ({ encodedResult }) => {
               const snapshot = encodedResult as {
                 readonly screenshot: {
 @@ -147,18 +174,20 @@ const registerPreviewSnapshot = Effect.fn("McpHttpServer.registerPreviewSnapshot
                   height: screenshot.height,
                 },
               };
-              return new McpSchema.CallToolResult({
+              return Effect.succeed(
-                isError: false,
+                new McpSchema.CallToolResult({
-                structuredContent: metadata,
+                  isError: false,
-                content: [
+                  structuredContent: metadata,
-                  { type: "text", text: JSON.stringify(metadata) },
+                  content: [
-                  {
+                    { type: "text", text: JSON.stringify(metadata) },
-                    type: "image",
+                    {
-                    data: new Uint8Array(Buffer.from(screenshot.data, "base64")),
+                      type: "image",
-                    mimeType: screenshot.mimeType,
+                      data: new Uint8Array(Buffer.from(screenshot.data, "base64")),
-                  },
+                      mimeType: screenshot.mimeType,
-                ],
+                    },
-              });
+                  ],
+                }),
+              );
             },
           }),
         );