Fix chat history paging around tool updates (#1247)

* Fix projected timeline paging

* Avoid full timeline fetches for plain pages

packages/app/src/hooks/use-agent-initialization.test.ts

@@ -34,7 +34,7 @@ afterEach(() => {
 });
 
 describe("ensureAgentIsInitialized", () => {
-  it("requests bounded canonical catch-up after the current cursor when authoritative history is loaded", () => {
+  it("requests bounded projected catch-up after the current cursor when authoritative history is loaded", () => {
     const client = makeClient();
     useSessionStore.getState().initializeSession(serverId, client as never);
     useSessionStore
@@ -56,12 +56,12 @@ describe("ensureAgentIsInitialized", () => {
       direction: "after",
       cursor: { epoch: "epoch-1", seq: 42 },
       limit: TIMELINE_FETCH_PAGE_SIZE,
-      projection: "canonical",
+      projection: "projected",
     });
     expect(getInitDeferred(getInitKey(serverId, agentId))?.requestDirection).toBe("after");
   });
 
-  it("requests a bounded canonical tail when no authoritative cursor is available", () => {
+  it("requests a bounded projected tail when no authoritative cursor is available", () => {
     const client = makeClient();
     useSessionStore.getState().initializeSession(serverId, client as never);
 
@@ -75,7 +75,7 @@ describe("ensureAgentIsInitialized", () => {
     expect(client.fetchAgentTimeline).toHaveBeenCalledWith(agentId, {
       direction: "tail",
       limit: TIMELINE_FETCH_PAGE_SIZE,
-      projection: "canonical",
+      projection: "projected",
     });
     expect(getInitDeferred(getInitKey(serverId, agentId))?.requestDirection).toBe("tail");
   });
@@ -107,7 +107,7 @@ describe("ensureAgentIsInitialized", () => {
 });
 
 describe("refreshAgent", () => {
-  it("fetches a bounded canonical tail after refreshing the agent", async () => {
+  it("fetches a bounded projected tail after refreshing the agent", async () => {
     const client = makeClient();
     useSessionStore.getState().initializeSession(serverId, client as never);
 
@@ -121,7 +121,7 @@ describe("refreshAgent", () => {
     expect(client.fetchAgentTimeline).toHaveBeenCalledWith(agentId, {
       direction: "tail",
       limit: TIMELINE_FETCH_PAGE_SIZE,
-      projection: "canonical",
+      projection: "projected",
     });
   });
 });