fix(contracts): read large file attachments from newer clients

packages/contracts/src/chatAttachment.test.ts

@@ -9,9 +9,128 @@ import {
   PROVIDER_SEND_TURN_MAX_FILE_BYTES,
   SnapShotAccessibility,
 } from "./chatAttachment.ts";
+import {
+  OrchestrationV2Command,
+  OrchestrationV2ConversationMessageJson,
+  OrchestrationV2ThreadLaunchInput,
+} from "./orchestrationV2.ts";
+import { ProviderRespondToUserInputInput, ProviderSendTurnInput } from "./provider.ts";
+import { UserInputAttachmentAnswerPayload } from "./providerPolicy.ts";
 
 const decodeAttachment = Schema.decodeUnknownEffect(ChatAttachment);
 const decodeSnapShotAccessibility = Schema.decodeUnknownEffect(SnapShotAccessibility);
+const decodeQuestionAnswer = Schema.decodeUnknownSync(UserInputAttachmentAnswerPayload);
+const decodeMessage = Schema.decodeUnknownSync(OrchestrationV2ConversationMessageJson);
+
+it.each([
+  ["provider turn", ProviderSendTurnInput, {}],
+  [
+    "provider question response",
+    ProviderRespondToUserInputInput,
+    { requestId: "request-1", answers: {} },
+  ],
+  [
+    "message dispatch",
+    OrchestrationV2Command,
+    {
+      type: "message.dispatch",
+      createdBy: "user",
+      creationSource: "web",
+      messageId: "message-1",
+      text: "hello",
+      dispatchMode: { type: "start_immediately" },
+    },
+  ],
+  [
+    "queued message edit",
+    OrchestrationV2Command,
+    { type: "queued-run.edit", runId: "run-1", text: "hello" },
+  ],
+  [
+    "runtime question response",
+    OrchestrationV2Command,
+    { type: "runtime-request.respond", requestId: "request-1", answers: {} },
+  ],
+  [
+    "thread launch",
+    OrchestrationV2ThreadLaunchInput,
+    {
+      projectId: "project-1",
+      title: "Thread",
+      modelSelection: { instanceId: "codex", model: "gpt-5.4" },
+      runtimeMode: "full-access",
+      interactionMode: "default",
+      workspaceStrategy: { type: "root" },
+    },
+  ],
+] as const)("caps new file attachments in %s", (name, schema, fields) => {
+  const input = (sizeBytes: number) => {
+    const attachments = [
+      { type: "file", id: "file-1", name: "report.pdf", mimeType: "application/pdf", sizeBytes },
+    ];
+    return {
+      commandId: "command-1",
+      threadId: "thread-1",
+      ...fields,
+      ...(name === "thread launch"
+        ? { initialMessage: { text: "hello", attachments } }
+        : name.includes("question response")
+          ? { attachmentsByQuestionId: { question: attachments } }
+          : { attachments }),
+    };
+  };
+  assert.strictEqual(Schema.is(schema)(input(PROVIDER_SEND_TURN_MAX_FILE_BYTES)), true);
+  assert.strictEqual(Schema.is(schema)(input(PROVIDER_SEND_TURN_MAX_FILE_BYTES + 1)), false);
+});
+
+it("reads historical question replies with files above the send limit", () => {
+  const payload = decodeQuestionAnswer({
+    requestId: "request-1",
+    answers: {},
+    attachmentsByQuestionId: {
+      question: [
+        {
+          type: "file",
+          id: "file-1",
+          name: "report.pdf",
+          mimeType: "application/pdf",
+          sizeBytes: PROVIDER_SEND_TURN_MAX_FILE_BYTES + 1,
+        },
+      ],
+    },
+  });
+  assert.strictEqual(
+    payload.attachmentsByQuestionId.question?.[0]?.sizeBytes,
+    PROVIDER_SEND_TURN_MAX_FILE_BYTES + 1,
+  );
+});
+
+it("reads complete historical messages with files above the send limit", () => {
+  const message = decodeMessage({
+    id: "message-1",
+    threadId: "thread-1",
+    runId: null,
+    nodeId: null,
+    createdBy: "user",
+    creationSource: "web",
+    role: "user",
+    text: "hello",
+    streaming: false,
+    createdAt: "2026-10-03T00:00:00.000Z",
+    updatedAt: "2026-10-03T00:00:00.000Z",
+    attachments: [
+      {
+        type: "file",
+        id: "file-1",
+        name: "report.pdf",
+        mimeType: "application/pdf",
+        sizeBytes: PROVIDER_SEND_TURN_MAX_FILE_BYTES + 1,
+      },
+    ],
+  });
+  assert.strictEqual(message.attachments[0]?.sizeBytes, PROVIDER_SEND_TURN_MAX_FILE_BYTES + 1);
+  assert.strictEqual(message.text, "hello");
+});
 
 // Attachments ride on persisted events and thread streams with no client
 // version negotiation. A type this build does not know must decode instead of
@@ -29,20 +148,20 @@ it.effect("tolerates attachment types from newer builds", () =>
   }),
 );
 
-// The tolerant member must not catch malformed known attachments: a file over
-// the size cap or an image with a bad mime has to fail its own schema, not
-// slide through the open one with those constraints unchecked.
 it.effect("rejects malformed known attachment types instead of tolerating them", () =>
   Effect.gen(function* () {
     const base = {
       id: "thread-1-00000000-0000-4000-8000-000000000003-pdf",
       name: "report.pdf",
       mimeType: "application/pdf",
     };
-    const oversizedFile = yield* Effect.exit(
-      decodeAttachment({ ...base, type: "file", sizeBytes: PROVIDER_SEND_TURN_MAX_FILE_BYTES + 1 }),
-    );
-    assert.strictEqual(Exit.isFailure(oversizedFile), true);
+    // A newer build may raise the upload cap; this build must still read those files.
+    const aboveUploadCap = PROVIDER_SEND_TURN_MAX_FILE_BYTES + 1;
+    const largeFile = yield* decodeAttachment({ ...base, type: "file", sizeBytes: aboveUploadCap });
+    assert.strictEqual(largeFile.sizeBytes, aboveUploadCap);
+
+    const emptyFile = yield* Effect.exit(decodeAttachment({ ...base, type: "file", sizeBytes: 0 }));
+    assert.strictEqual(Exit.isFailure(emptyFile), true);
     const badMimeImage = yield* Effect.exit(
       decodeAttachment({ ...base, type: "image", mimeType: "application/pdf", sizeBytes: 12 }),
     );

packages/contracts/src/chatAttachment.ts

@@ -164,17 +164,22 @@ export const ChatFileAttachment = Schema.Struct({
   id: ChatAttachmentId,
   name: TrimmedNonEmptyString.check(Schema.isMaxLength(255)),
   mimeType: TrimmedNonEmptyString.check(Schema.isMaxLength(100)),
-  sizeBytes: NonNegativeInt.check(
-    Schema.isGreaterThanOrEqualTo(1),
-    Schema.isLessThanOrEqualTo(PROVIDER_SEND_TURN_MAX_FILE_BYTES),
-  ),
+  sizeBytes: NonNegativeInt.check(Schema.isGreaterThanOrEqualTo(1)),
   /** Clipboard text folded by a client. Providers keep these path-only so the
       agent can inspect the file selectively instead of eagerly spending the
       same context the fold is intended to preserve. */
   source: Schema.optional(PastedTextAttachmentSource),
 });
 export type ChatFileAttachment = typeof ChatFileAttachment.Type;
 
+export const ChatFileAttachmentInput = Schema.Struct({
+  ...ChatFileAttachment.fields,
+  sizeBytes: ChatFileAttachment.fields.sizeBytes.check(
+    Schema.isLessThanOrEqualTo(PROVIDER_SEND_TURN_MAX_FILE_BYTES),
+  ),
+});
+export type ChatFileAttachmentInput = typeof ChatFileAttachmentInput.Type;
+
 /**
  * Catch-all for attachment types this build does not know. Attachments ride on
  * persisted events and thread streams, so a newer server or client must be able
@@ -217,6 +222,13 @@ export const ChatAttachment = Schema.Union([
 ]);
 export type ChatAttachment = typeof ChatAttachment.Type;
 
+export const ChatAttachmentInput = Schema.Union([
+  ChatImageAttachment,
+  ChatFileAttachmentInput,
+  ChatUnknownAttachment,
+]);
+export type ChatAttachmentInput = typeof ChatAttachmentInput.Type;
+
 export function getProviderAttachmentLimitError(
   attachments: ReadonlyArray<Pick<ChatAttachment, "type" | "mimeType" | "sizeBytes">>,
 ): string | undefined {

packages/contracts/src/orchestrationV2.ts

@@ -31,7 +31,7 @@ import {
   TrimmedNonEmptyString,
   TurnItemId,
 } from "./baseSchemas.ts";
-import { ChatAttachment } from "./chatAttachment.ts";
+import { ChatAttachment, ChatAttachmentInput } from "./chatAttachment.ts";
 import {
   OrchestrationGetFullThreadDiffInput,
   OrchestrationGetFullThreadDiffResult,
@@ -54,7 +54,7 @@ import {
   ProviderInteractionMode,
   ProviderRequestKind,
   ProviderUserInputAnswers,
-  UserInputAttachments,
+  UserInputAttachmentsInput,
   UserInputAttachmentAnswerPayload,
   RuntimeMode,
 } from "./providerPolicy.ts";
@@ -2672,7 +2672,7 @@ export const OrchestrationV2Command = Schema.Union([
     messageId: MessageId,
     text: Schema.String,
     context: Schema.optional(OrchestrationMessageContext),
-    attachments: Schema.Array(ChatAttachment),
+    attachments: Schema.Array(ChatAttachmentInput),
     /** Seed the temporary title and generate a durable replacement for the first message. */
     titleSeed: Schema.optional(TrimmedNonEmptyString),
     modelSelection: Schema.optional(ModelSelection),
@@ -2767,7 +2767,7 @@ export const OrchestrationV2Command = Schema.Union([
     text: Schema.String,
     // Full replacement list. Absent = leave the message's attachments as-is,
     // so pre-attachment clients editing text keep the original attachments.
-    attachments: Schema.optional(Schema.Array(ChatAttachment)),
+    attachments: Schema.optional(Schema.Array(ChatAttachmentInput)),
   }),
   Schema.Struct({
     type: Schema.Literal("runtime-request.respond"),
@@ -2776,7 +2776,7 @@ export const OrchestrationV2Command = Schema.Union([
     requestId: RuntimeRequestId,
     decision: Schema.optional(ProviderApprovalDecision),
     answers: Schema.optional(ProviderUserInputAnswers),
-    attachmentsByQuestionId: Schema.optional(UserInputAttachments),
+    attachmentsByQuestionId: Schema.optional(UserInputAttachmentsInput),
   }),
   Schema.Struct({
     type: Schema.Literal("thread.user-input.dismiss"),
@@ -2998,7 +2998,7 @@ export const OrchestrationV2ThreadLaunchInput = Schema.Struct({
       messageId: Schema.optional(MessageId),
       text: Schema.String,
       context: Schema.optional(OrchestrationMessageContext),
-      attachments: Schema.Array(ChatAttachment),
+      attachments: Schema.Array(ChatAttachmentInput),
     }),
   ),
 });

packages/contracts/src/provider.ts

@@ -11,7 +11,7 @@ import {
 import {
   getProviderAttachmentLimitError,
   PROVIDER_SEND_TURN_MAX_INPUT_CHARS,
-  ChatAttachment,
+  ChatAttachmentInput,
 } from "./chatAttachment.ts";
 import { ModelSelection } from "./modelSelection.ts";
 import {
@@ -21,7 +21,7 @@ import {
   ProviderRequestKind,
   ProviderSandboxMode,
   ProviderUserInputAnswers,
-  UserInputAttachments,
+  UserInputAttachmentsInput,
   RuntimeMode,
 } from "./providerPolicy.ts";
 import { ProviderInstanceId, ProviderDriverKind } from "./providerInstance.ts";
@@ -77,7 +77,7 @@ export const ProviderSendTurnInput = Schema.Struct({
     TrimmedNonEmptyString.check(Schema.isMaxLength(PROVIDER_SEND_TURN_MAX_INPUT_CHARS)),
   ),
   attachments: Schema.optional(
-    Schema.Array(ChatAttachment).check(
+    Schema.Array(ChatAttachmentInput).check(
       Schema.makeFilter((attachments) => getProviderAttachmentLimitError(attachments) ?? true),
     ),
   ),
@@ -115,7 +115,7 @@ export const ProviderRespondToUserInputInput = Schema.Struct({
   threadId: ThreadId,
   requestId: ApprovalRequestId,
   answers: ProviderUserInputAnswers,
-  attachmentsByQuestionId: Schema.optional(UserInputAttachments),
+  attachmentsByQuestionId: Schema.optional(UserInputAttachmentsInput),
 });
 export type ProviderRespondToUserInputInput = typeof ProviderRespondToUserInputInput.Type;
 

packages/contracts/src/providerPolicy.ts

@@ -1,6 +1,7 @@
 import {
   ChatImageAttachment,
   ChatFileAttachment,
+  ChatFileAttachmentInput,
   PROVIDER_SEND_TURN_MAX_ATTACHMENTS,
 } from "./chatAttachment.ts";
 import * as Schema from "effect/Schema";
@@ -75,6 +76,14 @@ export const UserInputAttachments = Schema.Record(
 );
 export type UserInputAttachments = typeof UserInputAttachments.Type;
 
+export const UserInputAttachmentsInput = Schema.Record(
+  Schema.String,
+  Schema.Array(Schema.Union([ChatImageAttachment, ChatFileAttachmentInput])).pipe(
+    Schema.check(Schema.isMaxLength(PROVIDER_SEND_TURN_MAX_ATTACHMENTS)),
+  ),
+);
+export type UserInputAttachmentsInput = typeof UserInputAttachmentsInput.Type;
+
 export const UserInputAttachmentAnswerPayload = Schema.Struct({
   requestId: TrimmedNonEmptyString,
   questionTextById: Schema.optional(Schema.Record(Schema.String, Schema.String)),