Revert the timeline optimistic and pagination rework (#2596)

* Add npm release track invariant and beta dist-tag procedure

* Revert "Keep older chat history and image previews stable (#2490)"

The timeline optimistic/pagination rework needs more work than main releases can wait for. Reverted together with #2484; both are reapplied on integration/timeline-optimistic-rework.

* Revert "Stop completed turns from appearing stuck (#2484)"

See the #2490 revert. #2490 built on this submission-authority change, so the two revert and reapply as a pair.

packages/server/src/server/agent/providers/mock-load-test-agent.test.ts

@@ -49,25 +49,6 @@ describe("MockLoadTestAgentClient", () => {
     });
   });
 
-  test("rejects the configured number of prompts before starting a retry", async () => {
-    const client = new MockLoadTestAgentClient();
-    const session = await client.createSession({
-      provider: "mock",
-      cwd: process.cwd(),
-      model: "ten-second-stream",
-      featureValues: { mockPromptRejections: 1 },
-    });
-
-    await expect(session.startTurn("Reject this prompt.")).rejects.toThrow(
-      "Requested mock prompt rejection",
-    );
-
-    await expect(session.startTurn("Accept this retry.")).resolves.toEqual({
-      turnId: expect.any(String),
-    });
-    await session.interrupt();
-  });
-
   test("returns schema-shaped JSON for structured branch-name generation", async () => {
     vi.useFakeTimers();
     const client = new MockLoadTestAgentClient();
@@ -284,39 +265,6 @@ describe("MockLoadTestAgentClient", () => {
     unsubscribe();
   });
 
-  test("emits a settled assistant Markdown image path selected by prompt", async () => {
-    vi.useFakeTimers();
-    const client = new MockLoadTestAgentClient();
-    const session = await client.createSession({
-      provider: "mock",
-      cwd: process.cwd(),
-      model: "ten-second-stream",
-    });
-    const events: AgentStreamEvent[] = [];
-    const unsubscribe = session.subscribe((event) => events.push(event));
-    const markdown = "![Fixture image](screenshots/fixture.png)";
-
-    const resultPromise = session.run(`Emit settled assistant image Markdown: ${markdown}`);
-    await vi.advanceTimersByTimeAsync(0);
-
-    expect(
-      events.flatMap((event): AgentTimelineItem[] =>
-        event.type === "timeline" && event.item.type === "assistant_message" ? [event.item] : [],
-      ),
-    ).toEqual([
-      expect.objectContaining({
-        type: "assistant_message",
-        text: markdown,
-      }),
-    ]);
-    await expect(resultPromise).resolves.toMatchObject({
-      sessionId: session.id,
-      finalText: markdown,
-      canceled: false,
-    });
-    unsubscribe();
-  });
-
   test("agent manager coalesces adjacent assistant tokens into fewer messages", async () => {
     vi.useFakeTimers();
     const workdir = mkdtempSync(join(tmpdir(), "paseo-mock-load-test-"));

packages/server/src/server/agent/providers/mock-load-test-agent.ts

@@ -36,8 +36,6 @@ export const MOCK_LOAD_TEST_DEFAULT_MODEL_ID = "five-minute-stream";
 const MOCK_LOAD_TEST_MODE_ID = "load-test";
 const MOCK_LOAD_TEST_DURATION_MS = 5 * 60 * 1000;
 const MOCK_LOAD_TEST_INTERVAL_MS = 40;
-const ONE_PIXEL_PNG_BASE64 =
-  "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAusB9Wl4Kj8AAAAASUVORK5CYII=";
 
 const CAPABILITIES: AgentCapabilityFlags = {
   supportsStreaming: true,
@@ -158,13 +156,6 @@ function shouldEmitTurnFailure(prompt: AgentPromptInput): boolean {
   return /emit\s+(?:a\s+)?synthetic\s+turn\s+failure/i.test(promptToText(prompt));
 }
 
-function parseSettledAssistantImageMarkdown(prompt: AgentPromptInput): string | null {
-  const match = /^emit settled assistant image markdown:\s*(!\[[^\]\r\n]*\]\(.+\))\s*$/i.exec(
-    promptToText(prompt),
-  );
-  return match?.[1] ?? null;
-}
-
 function parseMockQuestionPrompt(prompt: AgentPromptInput): MockQuestionPromptRequest | null {
   const text = promptToText(prompt);
   if (!/emit\s+(?:a\s+)?synthetic\s+questions?/i.test(text)) {
@@ -592,7 +583,6 @@ export class MockLoadTestAgentSession implements AgentSession {
   private modeId: string | null;
   private modelId: string | null;
   private readonly rewindError: string | null;
-  private remainingPromptRejections: number;
 
   constructor(options: { config: AgentSessionConfig; sessionId: string; logger?: Logger }) {
     this.id = options.sessionId;
@@ -603,13 +593,6 @@ export class MockLoadTestAgentSession implements AgentSession {
       typeof options.config.featureValues?.mockRewindError === "string"
         ? options.config.featureValues.mockRewindError
         : null;
-    const requestedPromptRejections = options.config.featureValues?.mockPromptRejections;
-    this.remainingPromptRejections =
-      typeof requestedPromptRejections === "number" &&
-      Number.isSafeInteger(requestedPromptRejections) &&
-      requestedPromptRejections > 0
-        ? requestedPromptRejections
-        : 0;
   }
 
   async run(prompt: AgentPromptInput, options?: AgentRunOptions): Promise<AgentRunResult> {
@@ -628,10 +611,6 @@ export class MockLoadTestAgentSession implements AgentSession {
     if (this.activeTurn) {
       throw new Error("Mock load-test provider already has an active turn");
     }
-    if (this.remainingPromptRejections > 0) {
-      this.remainingPromptRejections -= 1;
-      throw new Error("Requested mock prompt rejection");
-    }
 
     const profile = resolveModelProfile(this.modelId);
     const turnId = randomUUID();
@@ -678,13 +657,10 @@ export class MockLoadTestAgentSession implements AgentSession {
     const stress = parseAgentStreamStressPrompt(prompt);
     const questionPrompt = parseMockQuestionPrompt(prompt);
     const structuredBranchName = parseStructuredBranchNamePrompt(prompt);
-    const settledAssistantImageMarkdown = parseSettledAssistantImageMarkdown(prompt);
     if (shouldEmitTurnFailure(prompt)) {
       this.scheduleFailedTurn(turn);
     } else if (structuredBranchName) {
-      this.scheduleSettledAssistantTurn(turn, JSON.stringify(structuredBranchName));
-    } else if (settledAssistantImageMarkdown) {
-      this.scheduleSettledAssistantTurn(turn, settledAssistantImageMarkdown);
+      this.scheduleStructuredJsonTurn(turn, structuredBranchName);
     } else if (shouldEmitPlanApprovalPrompt(prompt)) {
       this.schedulePlanApprovalTurn(turn);
     } else if (questionPrompt) {
@@ -899,14 +875,14 @@ export class MockLoadTestAgentSession implements AgentSession {
     turn.timer.unref?.();
   }
 
-  private scheduleSettledAssistantTurn(turn: ActiveTurn, finalText: string): void {
+  private scheduleStructuredJsonTurn(turn: ActiveTurn, result: Record<string, string>): void {
     turn.timer = setTimeout(() => {
-      this.emitSettledAssistantTurn(turn, finalText);
+      this.emitStructuredJsonTurn(turn, result);
     }, 0);
     turn.timer.unref?.();
   }
 
-  private emitSettledAssistantTurn(turn: ActiveTurn, finalText: string): void {
+  private emitStructuredJsonTurn(turn: ActiveTurn, result: Record<string, string>): void {
     if (this.activeTurn !== turn) {
       return;
     }
@@ -918,6 +894,7 @@ export class MockLoadTestAgentSession implements AgentSession {
       turnId: turn.turnId,
     });
 
+    const finalText = JSON.stringify(result);
     this.emitTimeline(turn.turnId, {
       type: "assistant_message",
       text: finalText,
@@ -1128,14 +1105,9 @@ export class MockLoadTestAgentSession implements AgentSession {
         }),
       );
     } else {
-      const imageBytes = Buffer.from(ONE_PIXEL_PNG_BASE64, "base64");
-      const imagePayload = Buffer.concat([
-        imageBytes,
-        Buffer.alloc(Math.max(0, largePayload.bytes - imageBytes.length)),
-      ]).toString("base64");
       this.emitTimeline(turn.turnId, {
         type: "assistant_message",
-        text: `![Synthetic image](data:image/png;base64,${imagePayload})`,
+        text: `data:image/png;base64,${payload}`,
         messageId: turn.assistantMessageId,
       });
     }

packages/server/src/server/session.ts

@@ -6345,7 +6345,6 @@ export class Session {
             agentId,
             accepted: true,
             error: null,
-            outOfBand: true,
           },
         });
         return;
@@ -6373,7 +6372,6 @@ export class Session {
           agentId,
           accepted: true,
           error: null,
-          outOfBand: false,
         },
       });
     } catch (error) {