Coalesce prepended tool call history

packages/app/src/timeline/session-stream-reducers.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "vitest";
 import type { AgentStreamEventPayload } from "@server/shared/messages";
-import type { StreamItem } from "@/types/stream";
+import { hydrateStreamState, type AgentToolCallItem, type StreamItem } from "@/types/stream";
 import {
   createAgentStreamReducerQueue,
   processTimelineResponse,
@@ -31,6 +31,28 @@ function makeTimelineEntry(
   };
 }
 
+function makeToolCallTimelineEntry(
+  seq: number,
+  callId: string,
+  status: "running" | "completed",
+  detail: Record<string, unknown>,
+) {
+  return {
+    seqStart: seq,
+    seqEnd: seq,
+    provider: "claude",
+    item: {
+      type: "tool_call",
+      callId,
+      name: "Read",
+      status,
+      detail,
+      error: null,
+    },
+    timestamp: new Date(1000 + seq).toISOString(),
+  };
+}
+
 function makeTimelineEvent(
   text: string,
   type: string = "assistant_message",
@@ -97,6 +119,13 @@ function getUserTexts(items: StreamItem[]): string[] {
     .map((item) => item.text);
 }
 
+function getAgentToolCalls(items: StreamItem[]) {
+  return items.filter(
+    (item): item is AgentToolCallItem =>
+      item.kind === "tool_call" && item.payload.source === "agent",
+  );
+}
+
 const baseTimelineInput: ProcessTimelineResponseInput = {
   payload: {
     agentId: "agent-1",
@@ -510,6 +539,68 @@ describe("processTimelineResponse", () => {
     });
   });
 
+  it("coalesces tool call lifecycle rows across the older-page prepend boundary", () => {
+    const callId = "toolu_boundary";
+    const currentTail = hydrateStreamState(
+      [
+        {
+          event: {
+            type: "timeline",
+            provider: "claude",
+            item: makeToolCallTimelineEntry(3, callId, "completed", {
+              type: "read",
+              filePath: "/tmp/example.ts",
+            }).item,
+          } as AgentStreamEventPayload,
+          timestamp: new Date(3000),
+        },
+      ],
+      { source: "canonical" },
+    );
+    const existingCursor: TimelineCursor = {
+      epoch: "epoch-1",
+      startSeq: 3,
+      endSeq: 5,
+    };
+
+    const result = processTimelineResponse({
+      ...baseTimelineInput,
+      currentTail,
+      currentCursor: existingCursor,
+      payload: {
+        ...baseTimelineInput.payload,
+        direction: "before",
+        epoch: "epoch-1",
+        startCursor: { seq: 1 },
+        endCursor: { seq: 2 },
+        entries: [
+          makeToolCallTimelineEntry(1, callId, "running", {
+            type: "unknown",
+            input: { file_path: "/tmp/example.ts" },
+            output: null,
+          }),
+        ],
+      },
+    });
+
+    const toolCalls = getAgentToolCalls(result.tail);
+    expect(
+      toolCalls.map((item) => ({
+        id: item.id,
+        callId: item.payload.data.callId,
+        status: item.payload.data.status,
+        detailType: item.payload.data.detail.type,
+      })),
+    ).toEqual([
+      {
+        id: `agent_tool_${callId}`,
+        callId,
+        status: "completed",
+        detailType: "read",
+      },
+    ]);
+  });
+
   it("requests canonical catch-up when a projected entry overlaps unseen seqs", () => {
     const existingCursor: TimelineCursor = {
       epoch: "epoch-1",

packages/app/src/timeline/session-stream-reducers.ts

@@ -3,7 +3,12 @@ import type { AgentLifecycleStatus } from "@server/shared/agent-lifecycle";
 import type { Agent } from "@/stores/session-store";
 import { useSessionStore } from "@/stores/session-store";
 import type { StreamItem } from "@/types/stream";
-import { applyStreamEvent, hydrateStreamState, reduceStreamUpdate } from "@/types/stream";
+import {
+  applyStreamEvent,
+  coalesceAgentToolCallItems,
+  hydrateStreamState,
+  reduceStreamUpdate,
+} from "@/types/stream";
 
 const AGENT_STREAM_REDUCER_FLUSH_DELAY_MS = 16 * 3;
 
@@ -347,10 +352,10 @@ function mergePrependedCanonicalTail(olderTail: StreamItem[], currentTail: Strea
   const olderLast = olderTail.at(-1);
   const currentFirst = currentTail[0];
   if (olderLast?.kind !== "assistant_message" || currentFirst?.kind !== "assistant_message") {
-    return [...olderTail, ...currentTail];
+    return coalesceAgentToolCallItems([...olderTail, ...currentTail]);
   }
 
-  return [
+  return coalesceAgentToolCallItems([
     ...olderTail.slice(0, -1),
     {
       ...olderLast,
@@ -358,7 +363,7 @@ function mergePrependedCanonicalTail(olderTail: StreamItem[], currentTail: Strea
       timestamp: currentFirst.timestamp,
     },
     ...currentTail.slice(1),
-  ];
+  ]);
 }
 
 function applyTimelineIncrementalPath(args: {