diff --git a/docs/docs.json b/docs/docs.json
index 402d56aa380..b18409f6fbf 100644
--- a/docs/docs.json
+++ b/docs/docs.json
@@ -1033,6 +1033,7 @@
               {
                 "group": "Skills",
                 "pages": [
+                  "tools/btw",
                   "tools/creating-skills",
                   "tools/slash-commands",
                   "tools/skills",
diff --git a/docs/tools/btw.md b/docs/tools/btw.md
new file mode 100644
index 00000000000..38a30fcec77
--- /dev/null
+++ b/docs/tools/btw.md
@@ -0,0 +1,142 @@
+---
+summary: "Ephemeral side questions with /btw"
+read_when:
+  - You want to ask a quick side question about the current session
+  - You are implementing or debugging BTW behavior across clients
+title: "BTW Side Questions"
+---
+
+# BTW Side Questions
+
+`/btw` lets you ask a quick side question about the **current session** without
+turning that question into normal conversation history.
+
+It is modeled after Claude Code's `/btw` behavior, but adapted to OpenClaw's
+Gateway and multi-channel architecture.
+
+## What it does
+
+When you send:
+
+```text
+/btw what changed?
+```
+
+OpenClaw:
+
+1. snapshots the current session context,
+2. runs a separate **tool-less** model call,
+3. answers only the side question,
+4. leaves the main run alone,
+5. does **not** write the BTW question or answer to session history,
+6. emits the answer as a **live side result** rather than a normal assistant message.
+
+The important mental model is:
+
+- same session context
+- separate one-shot side query
+- no tool calls
+- no future context pollution
+- no transcript persistence
+
+## What it does not do
+
+`/btw` does **not**:
+
+- create a new durable session,
+- continue the unfinished main task,
+- run tools or agent tool loops,
+- write BTW question/answer data to transcript history,
+- appear in `chat.history`,
+- survive a reload.
+
+It is intentionally **ephemeral**.
+
+## How context works
+
+BTW uses the current session as **background context only**.
+
+If the main run is currently active, OpenClaw snapshots the current message
+state and includes the in-flight main prompt as background context, while
+explicitly telling the model:
+
+- answer only the side question,
+- do not resume or complete the unfinished main task,
+- do not emit tool calls or pseudo-tool calls.
+
+That keeps BTW isolated from the main run while still making it aware of what
+the session is about.
+
+## Delivery model
+
+BTW is **not** delivered as a normal assistant transcript message.
+
+At the Gateway protocol level:
+
+- normal assistant chat uses the `chat` event
+- BTW uses the `chat.side_result` event
+
+This separation is intentional. If BTW reused the normal `chat` event path,
+clients would treat it like regular conversation history.
+
+Because BTW uses a separate live event and is not replayed from
+`chat.history`, it disappears after reload.
+
+## Surface behavior
+
+### TUI
+
+In TUI, BTW is rendered inline in the current session view, but it remains
+ephemeral:
+
+- visibly distinct from a normal assistant reply
+- dismissible with `Enter` or `Esc`
+- not replayed on reload
+
+### External channels
+
+On channels like Telegram, WhatsApp, and Discord, BTW is delivered as a
+clearly labeled one-off reply because those surfaces do not have a local
+ephemeral overlay concept.
+
+The answer is still treated as a side result, not normal session history.
+
+### Control UI / web
+
+The Gateway emits BTW correctly as `chat.side_result`, and BTW is not included
+in `chat.history`, so the persistence contract is already correct for web.
+
+The current Control UI still needs a dedicated `chat.side_result` consumer to
+render BTW live in the browser. Until that client-side support lands, BTW is a
+Gateway-level feature with full TUI and external-channel behavior, but not yet
+a complete browser UX.
+
+## When to use BTW
+
+Use `/btw` when you want:
+
+- a quick clarification about the current work,
+- a factual side answer while a long run is still in progress,
+- a temporary answer that should not become part of future session context.
+
+Examples:
+
+```text
+/btw what file are we editing?
+/btw what does this error mean?
+/btw summarize the current task in one sentence
+/btw what is 17 * 19?
+```
+
+## When not to use BTW
+
+Do not use `/btw` when you want the answer to become part of the session's
+future working context.
+
+In that case, ask normally in the main session instead of using BTW.
+
+## Related
+
+- [Slash commands](/tools/slash-commands)
+- [Thinking Levels](/tools/thinking)
+- [Session](/concepts/session)
diff --git a/docs/tools/slash-commands.md b/docs/tools/slash-commands.md
index 0fe5f383f24..19072342b20 100644
--- a/docs/tools/slash-commands.md
+++ b/docs/tools/slash-commands.md
@@ -76,7 +76,7 @@ Text + native (when enabled):
 - `/allowlist` (list/add/remove allowlist entries)
 - `/approve <id> allow-once|allow-always|deny` (resolve exec approval prompts)
 - `/context [list|detail|json]` (explain “context”; `detail` shows per-file + per-tool + per-skill + system prompt size)
-- `/btw <question>` (ask a quick side question about the current session without changing future session context)
+- `/btw <question>` (ask an ephemeral side question about the current session without changing future session context; see [/tools/btw](/tools/btw))
 - `/export-session [path]` (alias: `/export`) (export current session to HTML with full system prompt)
 - `/whoami` (show your sender id; alias: `/id`)
 - `/session idle <duration|off>` (manage inactivity auto-unfocus for focused thread bindings)
@@ -224,3 +224,27 @@ Notes:
 - **`/stop`** targets the active chat session so it can abort the current run.
 - **Slack:** `channels.slack.slashCommand` is still supported for a single `/openclaw`-style command. If you enable `commands.native`, you must create one Slack slash command per built-in command (same names as `/help`). Command argument menus for Slack are delivered as ephemeral Block Kit buttons.
   - Slack native exception: register `/agentstatus` (not `/status`) because Slack reserves `/status`. Text `/status` still works in Slack messages.
+
+## BTW side questions
+
+`/btw` is a quick **side question** about the current session.
+
+Unlike normal chat:
+
+- it uses the current session as background context,
+- it runs as a separate **tool-less** one-shot call,
+- it does not change future session context,
+- it is not written to transcript history,
+- it is delivered as a live side result instead of a normal assistant message.
+
+That makes `/btw` useful when you want a temporary clarification while the main
+task keeps going.
+
+Example:
+
+```text
+/btw what are we doing right now?
+```
+
+See [BTW Side Questions](/tools/btw) for the full behavior and client UX
+details.
diff --git a/src/agents/btw.test.ts b/src/agents/btw.test.ts
index 943cdd140d0..b9f3a9c19f1 100644
--- a/src/agents/btw.test.ts
+++ b/src/agents/btw.test.ts
@@ -2,7 +2,6 @@ import { beforeEach, describe, expect, it, vi } from "vitest";
 import type { SessionEntry } from "../config/sessions.js";
 
 const streamSimpleMock = vi.fn();
-const appendCustomEntryMock = vi.fn();
 const buildSessionContextMock = vi.fn();
 const getLeafEntryMock = vi.fn();
 const branchMock = vi.fn();
@@ -13,11 +12,8 @@ const discoverModelsMock = vi.fn();
 const resolveModelWithRegistryMock = vi.fn();
 const getApiKeyForModelMock = vi.fn();
 const requireApiKeyMock = vi.fn();
-const acquireSessionWriteLockMock = vi.fn();
 const resolveSessionAuthProfileOverrideMock = vi.fn();
 const getActiveEmbeddedRunSnapshotMock = vi.fn();
-const waitForEmbeddedPiRunEndMock = vi.fn();
-const diagWarnMock = vi.fn();
 const diagDebugMock = vi.fn();
 
 vi.mock("@mariozechner/pi-ai", () => ({
@@ -31,7 +27,6 @@ vi.mock("@mariozechner/pi-coding-agent", () => ({
       branch: branchMock,
       resetLeaf: resetLeafMock,
       buildSessionContext: buildSessionContextMock,
-      appendCustomEntry: appendCustomEntryMock,
     }),
   },
 }));
@@ -54,13 +49,8 @@ vi.mock("./model-auth.js", () => ({
   requireApiKey: (...args: unknown[]) => requireApiKeyMock(...args),
 }));
 
-vi.mock("./session-write-lock.js", () => ({
-  acquireSessionWriteLock: (...args: unknown[]) => acquireSessionWriteLockMock(...args),
-}));
-
 vi.mock("./pi-embedded-runner/runs.js", () => ({
   getActiveEmbeddedRunSnapshot: (...args: unknown[]) => getActiveEmbeddedRunSnapshotMock(...args),
-  waitForEmbeddedPiRunEnd: (...args: unknown[]) => waitForEmbeddedPiRunEndMock(...args),
 }));
 
 vi.mock("./auth-profiles/session-override.js", () => ({
@@ -70,12 +60,11 @@ vi.mock("./auth-profiles/session-override.js", () => ({
 
 vi.mock("../logging/diagnostic.js", () => ({
   diagnosticLogger: {
-    warn: (...args: unknown[]) => diagWarnMock(...args),
     debug: (...args: unknown[]) => diagDebugMock(...args),
   },
 }));
 
-const { BTW_CUSTOM_TYPE, runBtwSideQuestion } = await import("./btw.js");
+const { runBtwSideQuestion } = await import("./btw.js");
 
 function makeAsyncEvents(events: unknown[]) {
   return {
@@ -99,7 +88,6 @@ function createSessionEntry(overrides: Partial<SessionEntry> = {}): SessionEntry
 describe("runBtwSideQuestion", () => {
   beforeEach(() => {
     streamSimpleMock.mockReset();
-    appendCustomEntryMock.mockReset();
     buildSessionContextMock.mockReset();
     getLeafEntryMock.mockReset();
     branchMock.mockReset();
@@ -110,11 +98,8 @@ describe("runBtwSideQuestion", () => {
     resolveModelWithRegistryMock.mockReset();
     getApiKeyForModelMock.mockReset();
     requireApiKeyMock.mockReset();
-    acquireSessionWriteLockMock.mockReset();
     resolveSessionAuthProfileOverrideMock.mockReset();
     getActiveEmbeddedRunSnapshotMock.mockReset();
-    waitForEmbeddedPiRunEndMock.mockReset();
-    diagWarnMock.mockReset();
     diagDebugMock.mockReset();
 
     buildSessionContextMock.mockReturnValue({
@@ -128,15 +113,11 @@ describe("runBtwSideQuestion", () => {
     });
     getApiKeyForModelMock.mockResolvedValue({ apiKey: "secret", mode: "api-key", source: "test" });
     requireApiKeyMock.mockReturnValue("secret");
-    acquireSessionWriteLockMock.mockResolvedValue({
-      release: vi.fn().mockResolvedValue(undefined),
-    });
     resolveSessionAuthProfileOverrideMock.mockResolvedValue("profile-1");
     getActiveEmbeddedRunSnapshotMock.mockReturnValue(undefined);
-    waitForEmbeddedPiRunEndMock.mockResolvedValue(true);
   });
 
-  it("streams blocks and persists a non-context custom entry", async () => {
+  it("streams blocks without persisting BTW data to disk", async () => {
     const onBlockReply = vi.fn().mockResolvedValue(undefined);
     streamSimpleMock.mockReturnValue(
       makeAsyncEvents([
@@ -212,17 +193,6 @@ describe("runBtwSideQuestion", () => {
       text: "Side answer.",
       btw: { question: "What changed?" },
     });
-    await vi.waitFor(() => {
-      expect(appendCustomEntryMock).toHaveBeenCalledWith(
-        BTW_CUSTOM_TYPE,
-        expect.objectContaining({
-          question: "What changed?",
-          answer: "Side answer.",
-          provider: "anthropic",
-          model: "claude-sonnet-4-5",
-        }),
-      );
-    });
   });
 
   it("returns a final payload when block streaming is unavailable", async () => {
@@ -641,14 +611,7 @@ describe("runBtwSideQuestion", () => {
     );
   });
 
-  it("returns the BTW answer and retries transcript persistence after a session lock", async () => {
-    acquireSessionWriteLockMock
-      .mockRejectedValueOnce(
-        new Error("session file locked (timeout 250ms): pid=123 /tmp/session.lock"),
-      )
-      .mockResolvedValueOnce({
-        release: vi.fn().mockResolvedValue(undefined),
-      });
+  it("returns the BTW answer without appending transcript custom entries", async () => {
     streamSimpleMock.mockReturnValue(
       makeAsyncEvents([
         {
@@ -688,26 +651,10 @@ describe("runBtwSideQuestion", () => {
     });
 
     expect(result).toEqual({ text: "323" });
-    await vi.waitFor(() => {
-      expect(waitForEmbeddedPiRunEndMock).toHaveBeenCalledWith("session-1", 30000);
-      expect(appendCustomEntryMock).toHaveBeenCalledWith(
-        BTW_CUSTOM_TYPE,
-        expect.objectContaining({
-          question: "What is 17 * 19?",
-          answer: "323",
-        }),
-      );
-    });
+    expect(buildSessionContextMock).toHaveBeenCalled();
   });
 
-  it("logs deferred persistence failures through the diagnostic logger", async () => {
-    acquireSessionWriteLockMock
-      .mockRejectedValueOnce(
-        new Error("session file locked (timeout 250ms): pid=123 /tmp/session.lock"),
-      )
-      .mockRejectedValueOnce(
-        new Error("session file locked (timeout 10000ms): pid=123 /tmp/session.lock"),
-      );
+  it("does not log transcript persistence warnings because BTW no longer writes to disk", async () => {
     streamSimpleMock.mockReturnValue(
       makeAsyncEvents([
         {
@@ -747,11 +694,9 @@ describe("runBtwSideQuestion", () => {
     });
 
     expect(result).toEqual({ text: "323" });
-    await vi.waitFor(() => {
-      expect(diagWarnMock).toHaveBeenCalledWith(
-        expect.stringContaining("btw transcript persistence skipped: sessionId=session-1"),
-      );
-    });
+    expect(diagDebugMock).not.toHaveBeenCalledWith(
+      expect.stringContaining("btw transcript persistence skipped"),
+    );
   });
 
   it("excludes tool results from BTW context to avoid replaying raw tool output", async () => {
diff --git a/src/agents/btw.ts b/src/agents/btw.ts
index 79ab9239479..d0f494277b1 100644
--- a/src/agents/btw.ts
+++ b/src/agents/btw.ts
@@ -21,19 +21,10 @@ import { getApiKeyForModel, requireApiKey } from "./model-auth.js";
 import { ensureOpenClawModelsJson } from "./models-config.js";
 import { EmbeddedBlockChunker, type BlockReplyChunking } from "./pi-embedded-block-chunker.js";
 import { resolveModelWithRegistry } from "./pi-embedded-runner/model.js";
-import {
-  getActiveEmbeddedRunSnapshot,
-  waitForEmbeddedPiRunEnd,
-} from "./pi-embedded-runner/runs.js";
+import { getActiveEmbeddedRunSnapshot } from "./pi-embedded-runner/runs.js";
 import { mapThinkingLevel } from "./pi-embedded-runner/utils.js";
 import { discoverAuthStorage, discoverModels } from "./pi-model-discovery.js";
 import { stripToolResultDetails } from "./session-transcript-repair.js";
-import { acquireSessionWriteLock } from "./session-write-lock.js";
-
-const BTW_CUSTOM_TYPE = "openclaw:btw";
-const BTW_PERSIST_TIMEOUT_MS = 250;
-const BTW_PERSIST_RETRY_WAIT_MS = 30_000;
-const BTW_PERSIST_RETRY_LOCK_MS = 10_000;
 
 type SessionManagerLike = {
   getLeafEntry?: () => {
@@ -47,97 +38,6 @@ type SessionManagerLike = {
   buildSessionContext: () => { messages?: unknown[] };
 };
 
-type BtwCustomEntryData = {
-  timestamp: number;
-  question: string;
-  answer: string;
-  provider: string;
-  model: string;
-  thinkingLevel: ThinkLevel | "off";
-  reasoningLevel: ReasoningLevel;
-  sessionKey?: string;
-  authProfileId?: string;
-  authProfileIdSource?: "auto" | "user";
-  usage?: unknown;
-};
-
-async function appendBtwCustomEntry(params: {
-  sessionFile: string;
-  timeoutMs: number;
-  entry: BtwCustomEntryData;
-}) {
-  const lock = await acquireSessionWriteLock({
-    sessionFile: params.sessionFile,
-    timeoutMs: params.timeoutMs,
-    allowReentrant: false,
-  });
-  try {
-    const persisted = SessionManager.open(params.sessionFile);
-    persisted.appendCustomEntry(BTW_CUSTOM_TYPE, params.entry);
-  } finally {
-    await lock.release();
-  }
-}
-
-function isSessionLockError(error: unknown): boolean {
-  const message = error instanceof Error ? error.message : String(error);
-  return message.includes("session file locked");
-}
-
-function deferBtwCustomEntryPersist(params: {
-  sessionId: string;
-  sessionFile: string;
-  entry: BtwCustomEntryData;
-}) {
-  void (async () => {
-    try {
-      await waitForEmbeddedPiRunEnd(params.sessionId, BTW_PERSIST_RETRY_WAIT_MS);
-      await appendBtwCustomEntry({
-        sessionFile: params.sessionFile,
-        timeoutMs: BTW_PERSIST_RETRY_LOCK_MS,
-        entry: params.entry,
-      });
-    } catch (error) {
-      const message = error instanceof Error ? error.message : String(error);
-      diag.warn(`btw transcript persistence skipped: sessionId=${params.sessionId} err=${message}`);
-    }
-  })();
-}
-
-async function persistBtwCustomEntry(params: {
-  sessionId: string;
-  sessionFile: string;
-  entry: BtwCustomEntryData;
-}) {
-  try {
-    await appendBtwCustomEntry({
-      sessionFile: params.sessionFile,
-      timeoutMs: BTW_PERSIST_TIMEOUT_MS,
-      entry: params.entry,
-    });
-  } catch (error) {
-    if (!isSessionLockError(error)) {
-      throw error;
-    }
-    deferBtwCustomEntryPersist({
-      sessionId: params.sessionId,
-      sessionFile: params.sessionFile,
-      entry: params.entry,
-    });
-  }
-}
-
-function persistBtwCustomEntryInBackground(params: {
-  sessionId: string;
-  sessionFile: string;
-  entry: BtwCustomEntryData;
-}) {
-  void persistBtwCustomEntry(params).catch((error) => {
-    const message = error instanceof Error ? error.message : String(error);
-    diag.warn(`btw transcript persistence skipped: sessionId=${params.sessionId} err=${message}`);
-  });
-}
-
 function collectTextContent(content: Array<{ type?: string; text?: string }>): string {
   return content
     .filter((part): part is { type: "text"; text: string } => part.type === "text")
@@ -347,7 +247,7 @@ export async function runBtwSideQuestion(
     throw new Error("No active session context.");
   }
 
-  const { model, authProfileId, authProfileIdSource } = await resolveRuntimeModel({
+  const { model, authProfileId } = await resolveRuntimeModel({
     cfg: params.cfg,
     provider: params.provider,
     model: params.model,
@@ -483,31 +383,9 @@ export async function runBtwSideQuestion(
     throw new Error("No BTW response generated.");
   }
 
-  const customEntry = {
-    timestamp: Date.now(),
-    question: params.question,
-    answer,
-    provider: model.provider,
-    model: model.id,
-    thinkingLevel: params.resolvedThinkLevel ?? "off",
-    reasoningLevel: params.resolvedReasoningLevel,
-    sessionKey: params.sessionKey,
-    authProfileId,
-    authProfileIdSource,
-    usage: finalMessage?.usage,
-  } satisfies BtwCustomEntryData;
-
-  persistBtwCustomEntryInBackground({
-    sessionId,
-    sessionFile,
-    entry: customEntry,
-  });
-
   if (emittedBlocks > 0) {
     return undefined;
   }
 
   return { text: answer };
 }
-
-export { BTW_CUSTOM_TYPE };