diff --git a/src/agents/pi-embedded-subscribe.code-span-awareness.e2e.test.ts b/src/agents/pi-embedded-subscribe.code-span-awareness.e2e.test.ts
index 59f7cfe66a..6bfe9db53d 100644
--- a/src/agents/pi-embedded-subscribe.code-span-awareness.e2e.test.ts
+++ b/src/agents/pi-embedded-subscribe.code-span-awareness.e2e.test.ts
@@ -1,5 +1,8 @@
 import { describe, expect, it, vi } from "vitest";
-import { createStubSessionHarness } from "./pi-embedded-subscribe.e2e-harness.js";
+import {
+  createStubSessionHarness,
+  emitAssistantTextDelta,
+} from "./pi-embedded-subscribe.e2e-harness.js";
 import { subscribeEmbeddedPiSession } from "./pi-embedded-subscribe.js";
 
 describe("subscribeEmbeddedPiSession thinking tag code span awareness", () => {
@@ -19,13 +22,9 @@ describe("subscribeEmbeddedPiSession thinking tag code span awareness", () => {
   it("does not strip thinking tags inside inline code backticks", () => {
     const { emit, onPartialReply } = createPartialReplyHarness();
 
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "The fix strips leaked `<thinking>` tags from messages.",
-      },
+    emitAssistantTextDelta({
+      emit,
+      delta: "The fix strips leaked `<thinking>` tags from messages.",
     });
 
     expect(onPartialReply).toHaveBeenCalled();
@@ -36,13 +35,9 @@ describe("subscribeEmbeddedPiSession thinking tag code span awareness", () => {
   it("does not strip thinking tags inside fenced code blocks", () => {
     const { emit, onPartialReply } = createPartialReplyHarness();
 
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "Example:\n  ````\n<thinking>code example</thinking>\n  ````\nDone.",
-      },
+    emitAssistantTextDelta({
+      emit,
+      delta: "Example:\n  ````\n<thinking>code example</thinking>\n  ````\nDone.",
     });
 
     expect(onPartialReply).toHaveBeenCalled();
@@ -53,13 +48,9 @@ describe("subscribeEmbeddedPiSession thinking tag code span awareness", () => {
   it("still strips actual thinking tags outside code spans", () => {
     const { emit, onPartialReply } = createPartialReplyHarness();
 
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "Hello <thinking>internal thought</thinking> world",
-      },
+    emitAssistantTextDelta({
+      emit,
+      delta: "Hello <thinking>internal thought</thinking> world",
     });
 
     expect(onPartialReply).toHaveBeenCalled();
diff --git a/src/agents/pi-embedded-subscribe.reply-tags.e2e.test.ts b/src/agents/pi-embedded-subscribe.reply-tags.e2e.test.ts
index c1359648e5..a76db60229 100644
--- a/src/agents/pi-embedded-subscribe.reply-tags.e2e.test.ts
+++ b/src/agents/pi-embedded-subscribe.reply-tags.e2e.test.ts
@@ -1,6 +1,10 @@
 import type { AssistantMessage } from "@mariozechner/pi-ai";
 import { describe, expect, it, vi } from "vitest";
-import { createStubSessionHarness } from "./pi-embedded-subscribe.e2e-harness.js";
+import {
+  createStubSessionHarness,
+  emitAssistantTextDelta,
+  emitAssistantTextEnd,
+} from "./pi-embedded-subscribe.e2e-harness.js";
 import { subscribeEmbeddedPiSession } from "./pi-embedded-subscribe.js";
 
 describe("subscribeEmbeddedPiSession reply tags", () => {
@@ -27,19 +31,8 @@ describe("subscribeEmbeddedPiSession reply tags", () => {
     const { emit, onBlockReply } = createBlockReplyHarness();
 
     emit({ type: "message_start", message: { role: "assistant" } });
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "[[reply_to_current]]\nHello",
-      },
-    });
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: { type: "text_end" },
-    });
+    emitAssistantTextDelta({ emit, delta: "[[reply_to_current]]\nHello" });
+    emitAssistantTextEnd({ emit });
 
     const assistantMessage = {
       role: "assistant",
@@ -58,16 +51,8 @@ describe("subscribeEmbeddedPiSession reply tags", () => {
     const { emit, onBlockReply } = createBlockReplyHarness();
 
     emit({ type: "message_start", message: { role: "assistant" } });
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: { type: "text_delta", delta: "Hello [[" },
-    });
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: { type: "text_end" },
-    });
+    emitAssistantTextDelta({ emit, delta: "Hello [[" });
+    emitAssistantTextEnd({ emit });
 
     const assistantMessage = {
       role: "assistant",
@@ -92,26 +77,10 @@ describe("subscribeEmbeddedPiSession reply tags", () => {
     });
 
     emit({ type: "message_start", message: { role: "assistant" } });
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: { type: "text_delta", delta: "[[reply_to:1897" },
-    });
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: { type: "text_delta", delta: "]] Hello" },
-    });
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: { type: "text_delta", delta: " world" },
-    });
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: { type: "text_end" },
-    });
+    emitAssistantTextDelta({ emit, delta: "[[reply_to:1897" });
+    emitAssistantTextDelta({ emit, delta: "]] Hello" });
+    emitAssistantTextDelta({ emit, delta: " world" });
+    emitAssistantTextEnd({ emit });
 
     const lastPayload = onPartialReply.mock.calls.at(-1)?.[0];
     expect(lastPayload?.text).toBe("Hello world");
diff --git a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.calls-onblockreplyflush-before-tool-execution-start-preserve.e2e.test.ts b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.calls-onblockreplyflush-before-tool-execution-start-preserve.e2e.test.ts
index 020d7e939d..e52ea881f9 100644
--- a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.calls-onblockreplyflush-before-tool-execution-start-preserve.e2e.test.ts
+++ b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.calls-onblockreplyflush-before-tool-execution-start-preserve.e2e.test.ts
@@ -1,21 +1,13 @@
 import { describe, expect, it, vi } from "vitest";
+import {
+  createStubSessionHarness,
+  emitAssistantTextDelta,
+} from "./pi-embedded-subscribe.e2e-harness.js";
 import { subscribeEmbeddedPiSession } from "./pi-embedded-subscribe.js";
 
-type StubSession = {
-  subscribe: (fn: (evt: unknown) => void) => () => void;
-};
-
-type SessionEventHandler = (evt: unknown) => void;
-
 describe("subscribeEmbeddedPiSession", () => {
   it("calls onBlockReplyFlush before tool_execution_start to preserve message boundaries", () => {
-    let handler: SessionEventHandler | undefined;
-    const session: StubSession = {
-      subscribe: (fn) => {
-        handler = fn;
-        return () => {};
-      },
-    };
+    const { session, emit } = createStubSessionHarness();
 
     const onBlockReplyFlush = vi.fn();
     const onBlockReply = vi.fn();
@@ -29,24 +21,17 @@ describe("subscribeEmbeddedPiSession", () => {
     });
 
     // Simulate text arriving before tool
-    handler?.({
+    emit({
       type: "message_start",
       message: { role: "assistant" },
     });
 
-    handler?.({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "First message before tool.",
-      },
-    });
+    emitAssistantTextDelta({ emit, delta: "First message before tool." });
 
     expect(onBlockReplyFlush).not.toHaveBeenCalled();
 
     // Tool execution starts - should trigger flush
-    handler?.({
+    emit({
       type: "tool_execution_start",
       toolName: "bash",
       toolCallId: "tool-flush-1",
@@ -56,7 +41,7 @@ describe("subscribeEmbeddedPiSession", () => {
     expect(onBlockReplyFlush).toHaveBeenCalledTimes(1);
 
     // Another tool - should flush again
-    handler?.({
+    emit({
       type: "tool_execution_start",
       toolName: "read",
       toolCallId: "tool-flush-2",
@@ -66,13 +51,7 @@ describe("subscribeEmbeddedPiSession", () => {
     expect(onBlockReplyFlush).toHaveBeenCalledTimes(2);
   });
   it("flushes buffered block chunks before tool execution", () => {
-    let handler: SessionEventHandler | undefined;
-    const session: StubSession = {
-      subscribe: (fn) => {
-        handler = fn;
-        return () => {};
-      },
-    };
+    const { session, emit } = createStubSessionHarness();
 
     const onBlockReply = vi.fn();
     const onBlockReplyFlush = vi.fn();
@@ -86,23 +65,16 @@ describe("subscribeEmbeddedPiSession", () => {
       blockReplyChunking: { minChars: 50, maxChars: 200 },
     });
 
-    handler?.({
+    emit({
       type: "message_start",
       message: { role: "assistant" },
     });
 
-    handler?.({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "Short chunk.",
-      },
-    });
+    emitAssistantTextDelta({ emit, delta: "Short chunk." });
 
     expect(onBlockReply).not.toHaveBeenCalled();
 
-    handler?.({
+    emit({
       type: "tool_execution_start",
       toolName: "bash",
       toolCallId: "tool-flush-buffer-1",
diff --git a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-append-text-end-content-is.e2e.test.ts b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-append-text-end-content-is.e2e.test.ts
index c268c11ff8..d25f3beb25 100644
--- a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-append-text-end-content-is.e2e.test.ts
+++ b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-append-text-end-content-is.e2e.test.ts
@@ -1,51 +1,21 @@
 import { describe, expect, it, vi } from "vitest";
-import { subscribeEmbeddedPiSession } from "./pi-embedded-subscribe.js";
-
-type StubSession = {
-  subscribe: (fn: (evt: unknown) => void) => () => void;
-};
+import {
+  createTextEndBlockReplyHarness,
+  emitAssistantTextDelta,
+  emitAssistantTextEnd,
+} from "./pi-embedded-subscribe.e2e-harness.js";
 
 describe("subscribeEmbeddedPiSession", () => {
   function setupTextEndSubscription() {
-    let handler: ((evt: unknown) => void) | undefined;
-    const session: StubSession = {
-      subscribe: (fn) => {
-        handler = fn;
-        return () => {};
-      },
-    };
-
     const onBlockReply = vi.fn();
-
-    const subscription = subscribeEmbeddedPiSession({
-      session: session as unknown as Parameters<typeof subscribeEmbeddedPiSession>[0]["session"],
-      runId: "run",
-      onBlockReply,
-      blockReplyBreak: "text_end",
-    });
-
-    const emit = (evt: unknown) => handler?.(evt);
+    const { emit, subscription } = createTextEndBlockReplyHarness({ onBlockReply });
 
     const emitDelta = (delta: string) => {
-      emit({
-        type: "message_update",
-        message: { role: "assistant" },
-        assistantMessageEvent: {
-          type: "text_delta",
-          delta,
-        },
-      });
+      emitAssistantTextDelta({ emit, delta });
     };
 
     const emitTextEnd = (content: string) => {
-      emit({
-        type: "message_update",
-        message: { role: "assistant" },
-        assistantMessageEvent: {
-          type: "text_end",
-          content,
-        },
-      });
+      emitAssistantTextEnd({ emit, content });
     };
 
     return { onBlockReply, subscription, emitDelta, emitTextEnd };
diff --git a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-duplicate-text-end-repeats-full.e2e.test.ts b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-duplicate-text-end-repeats-full.e2e.test.ts
index 7dc6b6156b..ade01e2180 100644
--- a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-duplicate-text-end-repeats-full.e2e.test.ts
+++ b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-duplicate-text-end-repeats-full.e2e.test.ts
@@ -1,80 +1,40 @@
 import { describe, expect, it, vi } from "vitest";
-import { createStubSessionHarness } from "./pi-embedded-subscribe.e2e-harness.js";
-import { subscribeEmbeddedPiSession } from "./pi-embedded-subscribe.js";
+import {
+  createTextEndBlockReplyHarness,
+  emitAssistantTextDelta,
+  emitAssistantTextEnd,
+} from "./pi-embedded-subscribe.e2e-harness.js";
 
 describe("subscribeEmbeddedPiSession", () => {
-  function createTextEndHarness(chunking?: {
-    minChars: number;
-    maxChars: number;
-    breakPreference: "newline";
-  }) {
-    const { session, emit } = createStubSessionHarness();
-    const onBlockReply = vi.fn();
-
-    const subscription = subscribeEmbeddedPiSession({
-      session,
-      runId: "run",
-      onBlockReply,
-      blockReplyBreak: "text_end",
-      blockReplyChunking: chunking,
-    });
-
-    return { emit, onBlockReply, subscription };
-  }
-
   it("does not duplicate when text_end repeats full content", () => {
-    const { emit, onBlockReply, subscription } = createTextEndHarness();
+    const onBlockReply = vi.fn();
+    const { emit, subscription } = createTextEndBlockReplyHarness({ onBlockReply });
 
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "Good morning!",
-      },
-    });
-
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_end",
-        content: "Good morning!",
-      },
-    });
+    emitAssistantTextDelta({ emit, delta: "Good morning!" });
+    emitAssistantTextEnd({ emit, content: "Good morning!" });
 
     expect(onBlockReply).toHaveBeenCalledTimes(1);
     expect(subscription.assistantTexts).toEqual(["Good morning!"]);
   });
   it("does not duplicate block chunks when text_end repeats full content", () => {
-    const { emit, onBlockReply } = createTextEndHarness({
-      minChars: 5,
-      maxChars: 40,
-      breakPreference: "newline",
+    const onBlockReply = vi.fn();
+    const { emit } = createTextEndBlockReplyHarness({
+      onBlockReply,
+      blockReplyChunking: {
+        minChars: 5,
+        maxChars: 40,
+        breakPreference: "newline",
+      },
     });
 
     const fullText = "First line\nSecond line\nThird line\n";
 
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: fullText,
-      },
-    });
+    emitAssistantTextDelta({ emit, delta: fullText });
 
     const callsAfterDelta = onBlockReply.mock.calls.length;
     expect(callsAfterDelta).toBeGreaterThan(0);
 
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_end",
-        content: fullText,
-      },
-    });
+    emitAssistantTextEnd({ emit, content: fullText });
 
     expect(onBlockReply).toHaveBeenCalledTimes(callsAfterDelta);
   });
diff --git a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-emit-duplicate-block-replies-text.e2e.test.ts b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-emit-duplicate-block-replies-text.e2e.test.ts
index ee7037a24c..44f829affb 100644
--- a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-emit-duplicate-block-replies-text.e2e.test.ts
+++ b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.does-not-emit-duplicate-block-replies-text.e2e.test.ts
@@ -1,45 +1,21 @@
 import type { AssistantMessage } from "@mariozechner/pi-ai";
 import { describe, expect, it, vi } from "vitest";
-import { createStubSessionHarness } from "./pi-embedded-subscribe.e2e-harness.js";
+import {
+  createStubSessionHarness,
+  createTextEndBlockReplyHarness,
+  emitAssistantTextDelta,
+  emitAssistantTextEnd,
+} from "./pi-embedded-subscribe.e2e-harness.js";
 import { subscribeEmbeddedPiSession } from "./pi-embedded-subscribe.js";
 
 describe("subscribeEmbeddedPiSession", () => {
   it("does not emit duplicate block replies when text_end repeats", () => {
-    const { session, emit } = createStubSessionHarness();
-
     const onBlockReply = vi.fn();
+    const { emit, subscription } = createTextEndBlockReplyHarness({ onBlockReply });
 
-    const subscription = subscribeEmbeddedPiSession({
-      session,
-      runId: "run",
-      onBlockReply,
-      blockReplyBreak: "text_end",
-    });
-
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "Hello block",
-      },
-    });
-
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_end",
-      },
-    });
-
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_end",
-      },
-    });
+    emitAssistantTextDelta({ emit, delta: "Hello block" });
+    emitAssistantTextEnd({ emit });
+    emitAssistantTextEnd({ emit });
 
     expect(onBlockReply).toHaveBeenCalledTimes(1);
     expect(subscription.assistantTexts).toEqual(["Hello block"]);
diff --git a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.emits-block-replies-text-end-does-not.e2e.test.ts b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.emits-block-replies-text-end-does-not.e2e.test.ts
index e13ffda120..cb383b04bf 100644
--- a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.emits-block-replies-text-end-does-not.e2e.test.ts
+++ b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.emits-block-replies-text-end-does-not.e2e.test.ts
@@ -1,42 +1,18 @@
 import type { AssistantMessage } from "@mariozechner/pi-ai";
 import { describe, expect, it, vi } from "vitest";
-import { createStubSessionHarness } from "./pi-embedded-subscribe.e2e-harness.js";
-import { subscribeEmbeddedPiSession } from "./pi-embedded-subscribe.js";
+import {
+  createTextEndBlockReplyHarness,
+  emitAssistantTextDelta,
+  emitAssistantTextEnd,
+} from "./pi-embedded-subscribe.e2e-harness.js";
 
 describe("subscribeEmbeddedPiSession", () => {
-  function createTextEndBlockReplyHarness() {
-    const { session, emit } = createStubSessionHarness();
-    const onBlockReply = vi.fn();
-
-    const subscription = subscribeEmbeddedPiSession({
-      session,
-      runId: "run",
-      onBlockReply,
-      blockReplyBreak: "text_end",
-    });
-
-    return { emit, onBlockReply, subscription };
-  }
-
   it("emits block replies on text_end and does not duplicate on message_end", () => {
-    const { emit, onBlockReply, subscription } = createTextEndBlockReplyHarness();
+    const onBlockReply = vi.fn();
+    const { emit, subscription } = createTextEndBlockReplyHarness({ onBlockReply });
 
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "Hello block",
-      },
-    });
-
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_end",
-      },
-    });
+    emitAssistantTextDelta({ emit, delta: "Hello block" });
+    emitAssistantTextEnd({ emit });
 
     expect(onBlockReply).toHaveBeenCalledTimes(1);
     const payload = onBlockReply.mock.calls[0][0];
@@ -54,18 +30,12 @@ describe("subscribeEmbeddedPiSession", () => {
     expect(subscription.assistantTexts).toEqual(["Hello block"]);
   });
   it("does not duplicate when message_end flushes and a late text_end arrives", () => {
-    const { emit, onBlockReply, subscription } = createTextEndBlockReplyHarness();
+    const onBlockReply = vi.fn();
+    const { emit, subscription } = createTextEndBlockReplyHarness({ onBlockReply });
 
     emit({ type: "message_start", message: { role: "assistant" } });
 
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "Hello block",
-      },
-    });
+    emitAssistantTextDelta({ emit, delta: "Hello block" });
 
     const assistantMessage = {
       role: "assistant",
@@ -79,14 +49,7 @@ describe("subscribeEmbeddedPiSession", () => {
     expect(subscription.assistantTexts).toEqual(["Hello block"]);
 
     // Some providers can still emit a late text_end; this must not re-emit.
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_end",
-        content: "Hello block",
-      },
-    });
+    emitAssistantTextEnd({ emit, content: "Hello block" });
 
     expect(onBlockReply).toHaveBeenCalledTimes(1);
     expect(subscription.assistantTexts).toEqual(["Hello block"]);
diff --git a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.filters-final-suppresses-output-without-start-tag.e2e.test.ts b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.filters-final-suppresses-output-without-start-tag.e2e.test.ts
index c5455dcd2a..9ccb78605a 100644
--- a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.filters-final-suppresses-output-without-start-tag.e2e.test.ts
+++ b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.filters-final-suppresses-output-without-start-tag.e2e.test.ts
@@ -2,6 +2,7 @@ import type { AssistantMessage } from "@mariozechner/pi-ai";
 import { describe, expect, it, vi } from "vitest";
 import {
   createStubSessionHarness,
+  emitAssistantTextDelta,
   emitMessageStartAndEndForAssistantText,
   expectSingleAgentEventText,
 } from "./pi-embedded-subscribe.e2e-harness.js";
@@ -23,14 +24,7 @@ describe("subscribeEmbeddedPiSession", () => {
     });
 
     emit({ type: "message_start", message: { role: "assistant" } });
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "<final>Hi there</final>",
-      },
-    });
+    emitAssistantTextDelta({ emit, delta: "<final>Hi there</final>" });
 
     expect(onPartialReply).toHaveBeenCalled();
     const firstPayload = onPartialReply.mock.calls[0][0];
@@ -39,14 +33,7 @@ describe("subscribeEmbeddedPiSession", () => {
     onPartialReply.mockReset();
 
     emit({ type: "message_start", message: { role: "assistant" } });
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "</final>Oops no start",
-      },
-    });
+    emitAssistantTextDelta({ emit, delta: "</final>Oops no start" });
 
     expect(onPartialReply).not.toHaveBeenCalled();
   });
@@ -75,14 +62,7 @@ describe("subscribeEmbeddedPiSession", () => {
       onPartialReply,
     });
 
-    emit({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "Hello world",
-      },
-    });
+    emitAssistantTextDelta({ emit, delta: "Hello world" });
 
     const payload = onPartialReply.mock.calls[0][0];
     expect(payload.text).toBe("Hello world");
diff --git a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.keeps-assistanttexts-final-answer-block-replies-are.e2e.test.ts b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.keeps-assistanttexts-final-answer-block-replies-are.e2e.test.ts
index 0bb70f3d8b..710b1f280f 100644
--- a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.keeps-assistanttexts-final-answer-block-replies-are.e2e.test.ts
+++ b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.keeps-assistanttexts-final-answer-block-replies-are.e2e.test.ts
@@ -1,51 +1,26 @@
 import type { AssistantMessage } from "@mariozechner/pi-ai";
 import { describe, expect, it, vi } from "vitest";
+import {
+  createStubSessionHarness,
+  emitAssistantTextDelta,
+  emitAssistantTextEnd,
+} from "./pi-embedded-subscribe.e2e-harness.js";
 import { subscribeEmbeddedPiSession } from "./pi-embedded-subscribe.js";
 
-type StubSession = {
-  subscribe: (fn: (evt: unknown) => void) => () => void;
-};
-
 describe("subscribeEmbeddedPiSession", () => {
   it("keeps assistantTexts to the final answer when block replies are disabled", () => {
-    let handler: ((evt: unknown) => void) | undefined;
-    const session: StubSession = {
-      subscribe: (fn) => {
-        handler = fn;
-        return () => {};
-      },
-    };
+    const { session, emit } = createStubSessionHarness();
 
     const subscription = subscribeEmbeddedPiSession({
-      session: session as unknown as Parameters<typeof subscribeEmbeddedPiSession>[0]["session"],
+      session,
       runId: "run",
       reasoningMode: "on",
     });
 
-    handler?.({ type: "message_start", message: { role: "assistant" } });
-    handler?.({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "Final ",
-      },
-    });
-    handler?.({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "answer",
-      },
-    });
-    handler?.({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_end",
-      },
-    });
+    emit({ type: "message_start", message: { role: "assistant" } });
+    emitAssistantTextDelta({ emit, delta: "Final " });
+    emitAssistantTextDelta({ emit, delta: "answer" });
+    emitAssistantTextEnd({ emit });
 
     const assistantMessage = {
       role: "assistant",
@@ -55,45 +30,25 @@ describe("subscribeEmbeddedPiSession", () => {
       ],
     } as AssistantMessage;
 
-    handler?.({ type: "message_end", message: assistantMessage });
+    emit({ type: "message_end", message: assistantMessage });
 
     expect(subscription.assistantTexts).toEqual(["Final answer"]);
   });
   it("suppresses partial replies when reasoning is enabled and block replies are disabled", () => {
-    let handler: ((evt: unknown) => void) | undefined;
-    const session: StubSession = {
-      subscribe: (fn) => {
-        handler = fn;
-        return () => {};
-      },
-    };
+    const { session, emit } = createStubSessionHarness();
 
     const onPartialReply = vi.fn();
 
     const subscription = subscribeEmbeddedPiSession({
-      session: session as unknown as Parameters<typeof subscribeEmbeddedPiSession>[0]["session"],
+      session,
       runId: "run",
       reasoningMode: "on",
       onPartialReply,
     });
 
-    handler?.({ type: "message_start", message: { role: "assistant" } });
-    handler?.({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "Draft ",
-      },
-    });
-    handler?.({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_delta",
-        delta: "reply",
-      },
-    });
+    emit({ type: "message_start", message: { role: "assistant" } });
+    emitAssistantTextDelta({ emit, delta: "Draft " });
+    emitAssistantTextDelta({ emit, delta: "reply" });
 
     expect(onPartialReply).not.toHaveBeenCalled();
 
@@ -105,15 +60,8 @@ describe("subscribeEmbeddedPiSession", () => {
       ],
     } as AssistantMessage;
 
-    handler?.({ type: "message_end", message: assistantMessage });
-    handler?.({
-      type: "message_update",
-      message: { role: "assistant" },
-      assistantMessageEvent: {
-        type: "text_end",
-        content: "Draft reply",
-      },
-    });
+    emit({ type: "message_end", message: assistantMessage });
+    emitAssistantTextEnd({ emit, content: "Draft reply" });
 
     expect(onPartialReply).not.toHaveBeenCalled();
     expect(subscription.assistantTexts).toEqual(["Final answer"]);
diff --git a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.suppresses-message-end-block-replies-message-tool.e2e.test.ts b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.suppresses-message-end-block-replies-message-tool.e2e.test.ts
index 2bc0382f57..737edc7fda 100644
--- a/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.suppresses-message-end-block-replies-message-tool.e2e.test.ts
+++ b/src/agents/pi-embedded-subscribe.subscribe-embedded-pi-session.suppresses-message-end-block-replies-message-tool.e2e.test.ts
@@ -1,6 +1,10 @@
 import type { AssistantMessage } from "@mariozechner/pi-ai";
 import { describe, expect, it, vi } from "vitest";
-import { createStubSessionHarness } from "./pi-embedded-subscribe.e2e-harness.js";
+import {
+  createStubSessionHarness,
+  emitAssistantTextDelta,
+  emitAssistantTextEnd,
+} from "./pi-embedded-subscribe.e2e-harness.js";
 import { subscribeEmbeddedPiSession } from "./pi-embedded-subscribe.js";
 
 function createBlockReplyHarness(blockReplyBreak: "message_end" | "text_end") {
@@ -48,16 +52,8 @@ function emitAssistantMessageEnd(emit: (evt: unknown) => void, text: string) {
 
 function emitAssistantTextEndBlock(emit: (evt: unknown) => void, text: string) {
   emit({ type: "message_start", message: { role: "assistant" } });
-  emit({
-    type: "message_update",
-    message: { role: "assistant" },
-    assistantMessageEvent: { type: "text_delta", delta: text },
-  });
-  emit({
-    type: "message_update",
-    message: { role: "assistant" },
-    assistantMessageEvent: { type: "text_end" },
-  });
+  emitAssistantTextDelta({ emit, delta: text });
+  emitAssistantTextEnd({ emit });
 }
 
 describe("subscribeEmbeddedPiSession", () => {