fix assistant streaming degradation on long threads

apps/server/src/orchestration/Layers/ProjectionPipeline.test.ts

@@ -11,6 +11,7 @@ import {
 } from "@t3tools/contracts";
 import * as NodeServices from "@effect/platform-node/NodeServices";
 import { assert, it } from "@effect/vitest";
+import * as DateTime from "effect/DateTime";
 import * as Effect from "effect/Effect";
 import * as FileSystem from "effect/FileSystem";
 import * as Layer from "effect/Layer";
@@ -33,6 +34,7 @@ import {
 import { OrchestrationProjectionSnapshotQueryLive } from "./ProjectionSnapshotQuery.ts";
 import { OrchestrationEngineService } from "../Services/OrchestrationEngine.ts";
 import { OrchestrationProjectionPipeline } from "../Services/ProjectionPipeline.ts";
+import { ProjectionSnapshotQuery } from "../Services/ProjectionSnapshotQuery.ts";
 import { ServerConfig } from "../../config.ts";
 
 const makeProjectionPipelinePrefixedTestLayer = (prefix: string) =>
@@ -596,6 +598,285 @@ it.layer(
   );
 });
 
+it.layer(
+  Layer.fresh(
+    OrchestrationProjectionSnapshotQueryLive.pipe(
+      Layer.provideMerge(
+        makeProjectionPipelinePrefixedTestLayer("t3-projection-streaming-append-"),
+      ),
+      Layer.provideMerge(RepositoryIdentityResolverLive),
+      Layer.provideMerge(NodeServices.layer),
+    ),
+  ),
+)("OrchestrationProjectionPipeline", (it) => {
+  it.effect("appends assistant streaming deltas in-place while preserving row metadata", () =>
+    Effect.gen(function* () {
+      const projectionPipeline = yield* OrchestrationProjectionPipeline;
+      const eventStore = yield* OrchestrationEventStore;
+      const sql = yield* SqlClient.SqlClient;
+      const first = DateTime.formatIso(DateTime.makeUnsafe("2026-02-24T00:00:01.000Z"));
+      const second = DateTime.formatIso(DateTime.makeUnsafe("2026-02-24T00:00:02.000Z"));
+      const third = DateTime.formatIso(DateTime.makeUnsafe("2026-02-24T00:00:03.000Z"));
+
+      const appendAndProject = (event: Parameters<typeof eventStore.append>[0]) =>
+        eventStore
+          .append(event)
+          .pipe(Effect.flatMap((savedEvent) => projectionPipeline.projectEvent(savedEvent)));
+
+      yield* appendAndProject({
+        type: "thread.message-sent",
+        eventId: EventId.make("evt-streaming-append-1"),
+        aggregateKind: "thread",
+        aggregateId: ThreadId.make("thread-streaming-append"),
+        occurredAt: first,
+        commandId: CommandId.make("cmd-streaming-append-1"),
+        causationEventId: null,
+        correlationId: CommandId.make("cmd-streaming-append-1"),
+        metadata: {},
+        payload: {
+          threadId: ThreadId.make("thread-streaming-append"),
+          messageId: MessageId.make("message-streaming-append"),
+          role: "assistant",
+          text: "Hello",
+          attachments: [
+            {
+              type: "image",
+              id: "thread-streaming-append-att-1",
+              name: "first.png",
+              mimeType: "image/png",
+              sizeBytes: 5,
+            },
+          ],
+          turnId: TurnId.make("turn-streaming-append"),
+          streaming: true,
+          createdAt: first,
+          updatedAt: first,
+        },
+      });
+
+      yield* appendAndProject({
+        type: "thread.message-sent",
+        eventId: EventId.make("evt-streaming-append-2"),
+        aggregateKind: "thread",
+        aggregateId: ThreadId.make("thread-streaming-append"),
+        occurredAt: second,
+        commandId: CommandId.make("cmd-streaming-append-2"),
+        causationEventId: null,
+        correlationId: CommandId.make("cmd-streaming-append-2"),
+        metadata: {},
+        payload: {
+          threadId: ThreadId.make("thread-streaming-append"),
+          messageId: MessageId.make("message-streaming-append"),
+          role: "assistant",
+          text: " world",
+          turnId: TurnId.make("turn-streaming-append"),
+          streaming: true,
+          createdAt: second,
+          updatedAt: second,
+        },
+      });
+
+      yield* appendAndProject({
+        type: "thread.message-sent",
+        eventId: EventId.make("evt-streaming-append-3"),
+        aggregateKind: "thread",
+        aggregateId: ThreadId.make("thread-streaming-append"),
+        occurredAt: third,
+        commandId: CommandId.make("cmd-streaming-append-3"),
+        causationEventId: null,
+        correlationId: CommandId.make("cmd-streaming-append-3"),
+        metadata: {},
+        payload: {
+          threadId: ThreadId.make("thread-streaming-append"),
+          messageId: MessageId.make("message-streaming-append"),
+          role: "assistant",
+          text: "!",
+          attachments: [],
+          turnId: TurnId.make("turn-streaming-append"),
+          streaming: true,
+          createdAt: third,
+          updatedAt: third,
+        },
+      });
+
+      const rows = yield* sql<{
+        readonly text: string;
+        readonly attachmentsJson: string | null;
+        readonly createdAt: string;
+        readonly updatedAt: string;
+        readonly isStreaming: number;
+      }>`
+        SELECT
+          text,
+          attachments_json AS "attachmentsJson",
+          created_at AS "createdAt",
+          updated_at AS "updatedAt",
+          is_streaming AS "isStreaming"
+        FROM projection_thread_messages
+        WHERE message_id = 'message-streaming-append'
+      `;
+
+      assert.equal(rows.length, 1);
+      assert.deepEqual(rows[0], {
+        text: "Hello world!",
+        attachmentsJson: "[]",
+        createdAt: first,
+        updatedAt: third,
+        isStreaming: 1,
+      });
+    }),
+  );
+
+  it.effect("exposes appended assistant streaming text through thread detail snapshots", () =>
+    Effect.gen(function* () {
+      const projectionPipeline = yield* OrchestrationProjectionPipeline;
+      const snapshotQuery = yield* ProjectionSnapshotQuery;
+      const eventStore = yield* OrchestrationEventStore;
+      const first = DateTime.formatIso(DateTime.makeUnsafe("2026-02-24T00:00:01.000Z"));
+      const second = DateTime.formatIso(DateTime.makeUnsafe("2026-02-24T00:00:02.000Z"));
+      const third = DateTime.formatIso(DateTime.makeUnsafe("2026-02-24T00:00:03.000Z"));
+
+      const appendAndProject = (event: Parameters<typeof eventStore.append>[0]) =>
+        eventStore
+          .append(event)
+          .pipe(Effect.flatMap((savedEvent) => projectionPipeline.projectEvent(savedEvent)));
+
+      yield* appendAndProject({
+        type: "project.created",
+        eventId: EventId.make("evt-client-visible-1"),
+        aggregateKind: "project",
+        aggregateId: ProjectId.make("project-client-visible"),
+        occurredAt: first,
+        commandId: CommandId.make("cmd-client-visible-1"),
+        causationEventId: null,
+        correlationId: CorrelationId.make("cmd-client-visible-1"),
+        metadata: {},
+        payload: {
+          projectId: ProjectId.make("project-client-visible"),
+          title: "Project",
+          workspaceRoot: "/tmp/project-client-visible",
+          defaultModelSelection: null,
+          scripts: [],
+          createdAt: first,
+          updatedAt: first,
+        },
+      });
+
+      yield* appendAndProject({
+        type: "thread.created",
+        eventId: EventId.make("evt-client-visible-2"),
+        aggregateKind: "thread",
+        aggregateId: ThreadId.make("thread-client-visible"),
+        occurredAt: first,
+        commandId: CommandId.make("cmd-client-visible-2"),
+        causationEventId: null,
+        correlationId: CorrelationId.make("cmd-client-visible-2"),
+        metadata: {},
+        payload: {
+          threadId: ThreadId.make("thread-client-visible"),
+          projectId: ProjectId.make("project-client-visible"),
+          title: "Thread",
+          modelSelection: {
+            instanceId: ProviderInstanceId.make("codex"),
+            model: "gpt-5-codex",
+          },
+          runtimeMode: "full-access",
+          interactionMode: "default",
+          branch: null,
+          worktreePath: null,
+          createdAt: first,
+          updatedAt: first,
+        },
+      });
+
+      yield* appendAndProject({
+        type: "thread.message-sent",
+        eventId: EventId.make("evt-client-visible-3"),
+        aggregateKind: "thread",
+        aggregateId: ThreadId.make("thread-client-visible"),
+        occurredAt: first,
+        commandId: CommandId.make("cmd-client-visible-3"),
+        causationEventId: null,
+        correlationId: CorrelationId.make("cmd-client-visible-3"),
+        metadata: {},
+        payload: {
+          threadId: ThreadId.make("thread-client-visible"),
+          messageId: MessageId.make("message-client-visible"),
+          role: "assistant",
+          text: "Hello",
+          turnId: null,
+          streaming: true,
+          createdAt: first,
+          updatedAt: first,
+        },
+      });
+
+      yield* appendAndProject({
+        type: "thread.message-sent",
+        eventId: EventId.make("evt-client-visible-4"),
+        aggregateKind: "thread",
+        aggregateId: ThreadId.make("thread-client-visible"),
+        occurredAt: second,
+        commandId: CommandId.make("cmd-client-visible-4"),
+        causationEventId: null,
+        correlationId: CorrelationId.make("cmd-client-visible-4"),
+        metadata: {},
+        payload: {
+          threadId: ThreadId.make("thread-client-visible"),
+          messageId: MessageId.make("message-client-visible"),
+          role: "assistant",
+          text: " world",
+          turnId: null,
+          streaming: true,
+          createdAt: second,
+          updatedAt: second,
+        },
+      });
+
+      yield* appendAndProject({
+        type: "thread.message-sent",
+        eventId: EventId.make("evt-client-visible-5"),
+        aggregateKind: "thread",
+        aggregateId: ThreadId.make("thread-client-visible"),
+        occurredAt: third,
+        commandId: CommandId.make("cmd-client-visible-5"),
+        causationEventId: null,
+        correlationId: CorrelationId.make("cmd-client-visible-5"),
+        metadata: {},
+        payload: {
+          threadId: ThreadId.make("thread-client-visible"),
+          messageId: MessageId.make("message-client-visible"),
+          role: "assistant",
+          text: "",
+          turnId: null,
+          streaming: false,
+          createdAt: third,
+          updatedAt: third,
+        },
+      });
+
+      const detail = yield* snapshotQuery.getThreadDetailById(
+        ThreadId.make("thread-client-visible"),
+      );
+
+      assert.equal(detail._tag, "Some");
+      if (detail._tag === "Some") {
+        assert.deepEqual(detail.value.messages, [
+          {
+            id: MessageId.make("message-client-visible"),
+            role: "assistant",
+            text: "Hello world",
+            turnId: null,
+            streaming: false,
+            createdAt: first,
+            updatedAt: third,
+          },
+        ]);
+      }
+    }),
+  );
+});
+
 it.layer(
   Layer.fresh(makeProjectionPipelinePrefixedTestLayer("t3-projection-attachments-rollback-")),
 )("OrchestrationProjectionPipeline", (it) => {

apps/server/src/orchestration/Layers/ProjectionPipeline.ts

@@ -701,6 +701,13 @@ const makeOrchestrationProjectionPipeline = Effect.fn("makeOrchestrationProjecti
             ...existingRow.value,
             updatedAt: event.occurredAt,
           });
+          if (
+            event.type === "thread.message-sent" &&
+            event.payload.role === "assistant" &&
+            event.payload.streaming
+          ) {
+            return;
+          }
           yield* refreshThreadShellSummary(event.payload.threadId);
           return;
         }
@@ -785,6 +792,27 @@ const makeOrchestrationProjectionPipeline = Effect.fn("makeOrchestrationProjecti
     )(function* (event, attachmentSideEffects) {
       switch (event.type) {
         case "thread.message-sent": {
+          if (event.payload.role === "assistant" && event.payload.streaming) {
+            const nextAttachments =
+              event.payload.attachments !== undefined
+                ? yield* materializeAttachmentsForProjection({
+                    attachments: event.payload.attachments,
+                  })
+                : undefined;
+            yield* projectionThreadMessageRepository.appendText({
+              messageId: event.payload.messageId,
+              threadId: event.payload.threadId,
+              turnId: event.payload.turnId,
+              role: event.payload.role,
+              textDelta: event.payload.text,
+              ...(nextAttachments !== undefined ? { attachments: [...nextAttachments] } : {}),
+              isStreaming: event.payload.streaming,
+              createdAt: event.payload.createdAt,
+              updatedAt: event.payload.updatedAt,
+            });
+            return;
+          }
+
           const existingMessage = yield* projectionThreadMessageRepository.getByMessageId({
             messageId: event.payload.messageId,
           });