diff --git a/packages/app/e2e/regression/btw-sidebar.spec.ts b/packages/app/e2e/regression/btw-sidebar.spec.ts
new file mode 100644
index 00000000000..4486701102c
--- /dev/null
+++ b/packages/app/e2e/regression/btw-sidebar.spec.ts
@@ -0,0 +1,145 @@
+import { base64Encode } from "@opencode/util/encode"
+import { expect, test } from "@playwright/test"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const directory = "C:/OpenCode/BtwSidebar"
+const projectID = "proj_btw_sidebar"
+const sessionID = "ses_btw_sidebar"
+const otherSessionID = "ses_btw_sidebar_other"
+const title = "Side question session"
+const otherTitle = "Other side question session"
+const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
+const sessionHref = (id: string) => `/server/${base64Encode(server)}/session/${id}`
+
+test.use({ viewport: { width: 1440, height: 900 } })
+
+test("answers /btw in the side panel without admitting a prompt", async ({ page }) => {
+  const generations: { sessionID: string; prompt: string }[] = []
+  const prompts: unknown[] = []
+  const generated = Promise.withResolvers<void>()
+  await mockOpenCodeServer(page, {
+    directory,
+    project: {
+      id: projectID,
+      worktree: directory,
+      vcs: "git",
+      name: "btw-sidebar",
+      time: { created: 1700000000000, updated: 1700000000000 },
+      sandboxes: [],
+    },
+    provider: {
+      all: [
+        {
+          id: "opencode",
+          name: "OpenCode",
+          models: { test: { id: "test", name: "Test", limit: { context: 200_000 } } },
+        },
+      ],
+      connected: ["opencode"],
+      default: { providerID: "opencode", modelID: "test" },
+    },
+    sessions: [
+      {
+        id: sessionID,
+        slug: sessionID,
+        projectID,
+        directory,
+        title,
+        version: "dev",
+        time: { created: 1700000000000, updated: 1700000000000 },
+      },
+      {
+        id: otherSessionID,
+        slug: otherSessionID,
+        projectID,
+        directory,
+        title: otherTitle,
+        version: "dev",
+        time: { created: 1700000001000, updated: 1700000001000 },
+      },
+    ],
+    pageMessages: () => ({ items: [] }),
+    vcsDiff: [],
+    onPrompt: (input) => prompts.push(input),
+    generate: async (input) => {
+      generations.push(input)
+      if (input.sessionID === otherSessionID) return { text: "This answer belongs to the **other session**." }
+      await generated.promise
+      return {
+        text: "The retry loop uses **exponential backoff** and stops after three attempts.\n\n```ts\nconst delay = 2 ** attempt\n```",
+      }
+    },
+  })
+  await page.addInitScript(
+    ({ directory, server, sessionID, otherSessionID }) => {
+      localStorage.setItem(
+        "opencode.global.dat:server",
+        JSON.stringify({
+          projects: { local: [{ worktree: directory, expanded: true }] },
+          lastProject: { local: directory },
+        }),
+      )
+      localStorage.setItem(
+        "opencode.window.browser.dat:tabs",
+        JSON.stringify([
+          { type: "session", server, sessionId: sessionID },
+          { type: "session", server, sessionId: otherSessionID },
+        ]),
+      )
+    },
+    { directory, server, sessionID, otherSessionID },
+  )
+
+  await page.goto(sessionHref(sessionID))
+  await expectSessionTitle(page, title)
+  const editor = page.locator('[data-component="composer-editor"]')
+  await expect(editor).toBeEditable()
+
+  await editor.fill("/btw")
+  const suggestion = page.locator('[data-suggestion-id="session.btw"]')
+  await expect(suggestion).toBeVisible()
+  await suggestion.click()
+  await expect(editor).toHaveText("/btw ")
+  await editor.press("Enter")
+
+  const panel = page.locator('[data-slot="session-btw-panel"]')
+  await expect(panel).toBeHidden()
+  await expect(page.getByText("Add a question after /btw", { exact: true })).toBeVisible()
+  expect(generations).toEqual([])
+  expect(prompts).toEqual([])
+
+  await editor.fill("/btw how does the retry loop work?")
+  await editor.press("Enter")
+
+  const tab = page.getByRole("tab", { name: "/btw" })
+  await expect(panel).toBeVisible()
+  await expect(panel.getByRole("textbox")).toHaveCount(0)
+  await expect(panel.getByRole("status")).toContainText("Working")
+  await expect(tab).toHaveAttribute("data-selected", "")
+  generated.resolve()
+  await expect(panel.getByText("how does the retry loop work?", { exact: true })).toBeVisible()
+  await expect(panel.getByText("exponential backoff", { exact: false })).toBeVisible()
+  await expect(panel.getByText("const delay = 2 ** attempt", { exact: true })).toBeVisible()
+  expect(generations).toHaveLength(1)
+  expect(generations[0]?.sessionID).toBe(sessionID)
+  expect(generations[0]?.prompt).toContain("how does the retry loop work?")
+  expect(prompts).toEqual([])
+  await expect(editor).toHaveText("")
+
+  await page.locator(`[data-titlebar-tab-link][href="${sessionHref(otherSessionID)}"]`).click()
+  await expectSessionTitle(page, otherTitle)
+  await editor.fill("/btw what belongs here?")
+  await editor.press("Enter")
+  await expect(panel.getByText("other session", { exact: false })).toBeVisible()
+
+  await page.locator(`[data-titlebar-tab-link][href="${sessionHref(sessionID)}"]`).click()
+  await expectSessionTitle(page, title)
+  await expect(panel.getByText("exponential backoff", { exact: false })).toBeVisible()
+  await expect(panel.getByText("other session", { exact: false })).toHaveCount(0)
+
+  await page.reload()
+  await expectSessionTitle(page, title)
+  await expect(page.getByRole("tab", { name: "/btw" })).toHaveCount(0)
+  await expect(page.locator('[data-slot="session-btw-panel"]')).toHaveCount(0)
+})
diff --git a/packages/app/e2e/utils/mock-api.ts b/packages/app/e2e/utils/mock-api.ts
index d51f96264ca..a0a6bc14a25 100644
--- a/packages/app/e2e/utils/mock-api.ts
+++ b/packages/app/e2e/utils/mock-api.ts
@@ -197,6 +197,13 @@ const Group = HttpApiGroup.make("mock")
       success: Json,
     }),
   )
+  .add(
+    HttpApiEndpoint.post("sessionGenerate", "/api/session/:sessionID/generate", {
+      params: SessionParams,
+      payload: Schema.Struct({ prompt: Schema.String }),
+      success: Json,
+    }),
+  )
   .add(
     HttpApiEndpoint.post("sessionSwitchAgent", "/api/session/:sessionID/agent", {
       params: SessionParams,
diff --git a/packages/app/e2e/utils/mock-server.ts b/packages/app/e2e/utils/mock-server.ts
index 1612ca3583b..f5d19f7a027 100644
--- a/packages/app/e2e/utils/mock-server.ts
+++ b/packages/app/e2e/utils/mock-server.ts
@@ -42,6 +42,7 @@ export interface MockServerConfig {
   sessionStatus?: Record<string, unknown> | (() => Record<string, unknown>)
   inbox?: unknown[] | (() => unknown[])
   onPrompt?: (input: { sessionID: string; body: Record<string, unknown> }) => void
+  generate?: (input: { sessionID: string; prompt: string }) => { text: string } | Promise<{ text: string }>
   onInboxChange?: (input: { sessionID: string; inboxID: string; action: "cancel" | "steer" | "queue" }) => void
 }
 
@@ -456,6 +457,12 @@ function mockHandlers(config: MockServerConfig, state: { cursors: Map<string, st
               },
             }
           }),
+        sessionGenerate: (ctx) =>
+          Effect.promise(async () => ({
+            data: (await config.generate?.({ sessionID: ctx.params.sessionID, prompt: ctx.payload.prompt })) ?? {
+              text: "Side-question answer",
+            },
+          })),
         sessionInboxCancel: (ctx) =>
           Effect.sync(() =>
             config.onInboxChange?.({ sessionID: ctx.params.sessionID, inboxID: ctx.params.inboxID, action: "cancel" }),
diff --git a/packages/app/src/composer/client-slash-command.test.ts b/packages/app/src/composer/client-slash-command.test.ts
new file mode 100644
index 00000000000..7047164b50b
--- /dev/null
+++ b/packages/app/src/composer/client-slash-command.test.ts
@@ -0,0 +1,32 @@
+import { describe, expect, test } from "bun:test"
+import { parseClientSlashCommand } from "./client-slash-command"
+
+const options = [
+  { id: "session.btw", trigger: "btw", arguments: true, type: "builtin" as const },
+  { id: "custom.btw", trigger: "custom", type: "custom" as const },
+  { id: "model.choose", trigger: "model", type: "builtin" as const },
+]
+
+describe("parseClientSlashCommand", () => {
+  test("parses inline and multiline arguments", () => {
+    expect(parseClientSlashCommand(options, "/btw why this approach?")).toEqual({
+      id: "session.btw",
+      input: "why this approach?",
+    })
+    expect(parseClientSlashCommand(options, "/btw\nwhy this approach?")).toEqual({
+      id: "session.btw",
+      input: "why this approach?",
+    })
+  })
+
+  test("accepts a bare argument command", () => {
+    expect(parseClientSlashCommand(options, "/btw")).toEqual({ id: "session.btw", input: "" })
+  })
+
+  test("rejects prefixes, custom commands, and ordinary slash commands", () => {
+    expect(parseClientSlashCommand(options, "/btwx nope")).toBeUndefined()
+    expect(parseClientSlashCommand(options, "/custom nope")).toBeUndefined()
+    expect(parseClientSlashCommand(options, "/model opus")).toBeUndefined()
+    expect(parseClientSlashCommand(options, "ask /btw later")).toBeUndefined()
+  })
+})
diff --git a/packages/app/src/composer/client-slash-command.ts b/packages/app/src/composer/client-slash-command.ts
new file mode 100644
index 00000000000..9e67ef393da
--- /dev/null
+++ b/packages/app/src/composer/client-slash-command.ts
@@ -0,0 +1,24 @@
+type ClientSlashCommand = {
+  id: string
+  trigger: string
+  arguments?: boolean
+  type: "builtin" | "custom"
+}
+
+export function parseSlashCommand(text: string) {
+  if (!text.startsWith("/")) return
+  const separator = text.search(/\s/)
+  const name = text.slice(1, separator === -1 ? undefined : separator)
+  return { name, input: separator === -1 ? "" : text.slice(separator).trim() }
+}
+
+export function parseClientSlashCommand(options: readonly ClientSlashCommand[], text: string) {
+  const command = parseSlashCommand(text)
+  if (!command) return
+  const option = options.find((item) => item.type === "builtin" && item.arguments && item.trigger === command.name)
+  if (!option) return
+  return {
+    id: option.id,
+    input: command.input,
+  }
+}
diff --git a/packages/app/src/composer/model.ts b/packages/app/src/composer/model.ts
index c785e95da7c..1faa70cd920 100644
--- a/packages/app/src/composer/model.ts
+++ b/packages/app/src/composer/model.ts
@@ -24,6 +24,7 @@ import { createComposerHistory } from "./history/store"
 import { composerPlaceholder } from "./placeholder"
 import { createComposerSubmit } from "./submit"
 import { useAttachmentDestination } from "./attachments/destination"
+import { parseClientSlashCommand } from "./client-slash-command"
 
 export type ComposerModel = ComposerEditorModel & {
   readonly model: ComposerControls["model"]
@@ -73,9 +74,7 @@ export function createComposerModel(adapter: ComposerAdapter, options?: { queue?
       return [...result, path]
     }, [])
   })
-  const attachments = createMemo(() =>
-    prompt.current().filter(isAttachment),
-  )
+  const attachments = createMemo(() => prompt.current().filter(isAttachment))
   const commentCount = createMemo(() => {
     if (mode() === "shell") return 0
     return prompt.context.items().filter((item) => !!item.comment?.trim()).length
@@ -242,6 +241,7 @@ export function createComposerModel(adapter: ComposerAdapter, options?: { queue?
         trigger: item.slash!,
         title: item.title,
         description: item.description,
+        arguments: item.slashArguments,
         type: "builtin" as const,
       })),
   ])
@@ -299,6 +299,11 @@ export function createComposerModel(adapter: ComposerAdapter, options?: { queue?
       clear: comments.clear,
       restore: restoreHistoryComments,
     },
+    clientCommand: (text) => {
+      const selected = parseClientSlashCommand(slashCommands(), text)
+      if (!selected) return
+      return () => command.trigger(selected.id, "slash", selected.input)
+    },
   })
   const controller = createComposerEditor({
     store: prompt.store,
@@ -340,6 +345,7 @@ export function createComposerModel(adapter: ComposerAdapter, options?: { queue?
       if (item.kind !== "command") return
       const selected = slashCommands().find((entry) => entry.id === item.id)
       if (!selected || selected.type === "custom") return
+      if (selected.arguments) return
       return () => command.trigger(selected.id, "slash")
     },
     attachments: {
diff --git a/packages/app/src/composer/submit.test.ts b/packages/app/src/composer/submit.test.ts
index 9db0102c368..355cbcd2a53 100644
--- a/packages/app/src/composer/submit.test.ts
+++ b/packages/app/src/composer/submit.test.ts
@@ -54,14 +54,17 @@ function submitInput(
   mode: "normal" | "shell" = "normal",
   commands: () => readonly { name: string }[] | undefined = () => [],
   history: string[] = [],
+  clientCommand?: (text: string) => (() => void | Promise<void>) | undefined,
 ) {
   return createComposerSubmit({
     adapter,
     mode: () => mode,
     commands,
+    clientCommand,
     editor: () => undefined,
     queueScroll() {},
-    addToHistory: (prompt) => history.push(`add:${prompt.map((part) => ("content" in part ? part.content : part.type)).join("")}`),
+    addToHistory: (prompt) =>
+      history.push(`add:${prompt.map((part) => ("content" in part ? part.content : part.type)).join("")}`),
     removeFromHistory: (prompt) =>
       history.push(`remove:${prompt.map((part) => ("content" in part ? part.content : part.type)).join("")}`),
     resetHistory() {},
@@ -118,6 +121,61 @@ function session(input: {
 }
 
 describe("Composer submission", () => {
+  test("runs a client argument command without admitting it to the session", async () => {
+    const state = createMemoryComposerState().capture()
+    state.set([
+      { type: "text", content: "/btw why this approach?", start: 0, end: 23 },
+      {
+        type: "image",
+        id: "attachment",
+        filename: "diagram.png",
+        mime: "image/png",
+        blob: { id: "attachment", url: "data:image/png;base64,YQ==" },
+      },
+    ])
+    state.context.add({ type: "file", path: "src/retry.ts" })
+    const calls: string[] = []
+    const target = session({
+      calls,
+      prompt: async () => {
+        throw new Error("client command must not call prompt")
+      },
+    })
+    const adapter: ActiveComposerAdapter = {
+      kind: "active-session",
+      state,
+      ready: () => true,
+      controls,
+      working: () => false,
+      session: () => target,
+      interrupt: async () => undefined,
+      submitted() {},
+      setEditor() {},
+    }
+
+    const history: string[] = []
+    await submitInput(adapter, undefined, "normal", undefined, history, (text) => {
+      expect(text).toBe("/btw why this approach?")
+      return () => {
+        calls.push("btw")
+      }
+    }).submit(new Event("submit"))
+
+    expect(calls).toEqual(["btw"])
+    expect(history).toEqual([])
+    expect(state.current()).toEqual([
+      { type: "text", content: "", start: 0, end: 0 },
+      {
+        type: "image",
+        id: "attachment",
+        filename: "diagram.png",
+        mime: "image/png",
+        blob: { id: "attachment", url: "data:image/png;base64,YQ==" },
+      },
+    ])
+    expect(state.context.items()).toHaveLength(1)
+  })
+
   test("applies the captured agent and model before a custom command without passing over its overrides", async () => {
     const state = createMemoryComposerState({ prompt: "/review changes" }).capture()
     const calls: string[] = []
@@ -625,12 +683,7 @@ describe("Composer submission", () => {
       },
     }
 
-    await submitInput(
-      adapter,
-      undefined,
-      "normal",
-      () => catalog,
-    ).submit(new Event("submit"))
+    await submitInput(adapter, undefined, "normal", () => catalog).submit(new Event("submit"))
 
     expect(await sent.promise).toBe("command")
     expect(requests).toEqual([
diff --git a/packages/app/src/composer/submit.ts b/packages/app/src/composer/submit.ts
index 762fc07978a..f327aa6a0f1 100644
--- a/packages/app/src/composer/submit.ts
+++ b/packages/app/src/composer/submit.ts
@@ -11,6 +11,7 @@ import { setCursorPosition } from "./editor/dom"
 import { blobDataUrl, resolveBlobUrl } from "@/runtime/persistence/drafts"
 import { isAttachment } from "./prompt-parts"
 import type { ModelSelection } from "@/providers/models/selection"
+import { parseSlashCommand } from "./client-slash-command"
 
 const submitting = new WeakSet<object>()
 
@@ -37,6 +38,7 @@ type ComposerSubmitInput = {
   setMode: (mode: "normal" | "shell") => void
   closePopover: () => void
   delivery?: (alternate: boolean) => ComposerDelivery
+  clientCommand?: (text: string) => (() => void | Promise<void>) | undefined
   notify: {
     missingSelection: () => void
     failed: (kind: "shell" | "command" | "prompt", error: unknown) => void
@@ -52,15 +54,31 @@ export function createComposerSubmit(input: ComposerSubmitInput) {
   const submit = async (event: globalThis.Event, options?: { alternate?: boolean }) => {
     event.preventDefault()
 
+    const prompt = clonePrompt(input.adapter.state.current())
+    const text = submissionText(prompt)
+    const clientCommand = input.mode() === "normal" ? input.clientCommand?.(text) : undefined
+    if (clientCommand) {
+      if (submitting.has(input.adapter.state)) return
+      submitting.add(input.adapter.state)
+      try {
+        clearClientCommand(input, prompt)
+        await clientCommand()
+      } catch (error) {
+        input.notify.failed("command", error)
+      } finally {
+        submitting.delete(input.adapter.state)
+      }
+      return
+    }
     const submission = createComposerSubmission({
       target: input.adapter.state,
-      prompt: clonePrompt(input.adapter.state.current()),
+      prompt,
       context: input.adapter.state.context.items().map((item) => ({
         ...item,
         selection: item.selection ? { ...item.selection } : undefined,
       })),
     })
-    const read = readSubmission(input, submission.prompt, submission.context, options?.alternate ?? false)
+    const read = readSubmission(input, submission.prompt, submission.context, text, options?.alternate ?? false)
     if (!read) {
       if (input.adapter.working() && input.adapter.kind === "active-session") void input.adapter.interrupt()
       return
@@ -150,6 +168,17 @@ export function createComposerSubmit(input: ComposerSubmitInput) {
   }
 }
 
+function clearClientCommand(input: ComposerSubmitInput, prompt: Prompt) {
+  input.adapter.state.set([{ type: "text", content: "", start: 0, end: 0 }, ...prompt.filter(isAttachment)], 0)
+  input.adapter.state.mode.set("normal")
+  input.setMode("normal")
+  input.closePopover()
+}
+
+function submissionText(prompt: Prompt) {
+  return prompt.map((part) => ("content" in part ? part.content : "")).join("")
+}
+
 function handoffMessage(value: ComposerSubmission): SessionMessageUser {
   return {
     id: value.id,
@@ -193,9 +222,9 @@ function readSubmission(
   input: ComposerSubmitInput,
   prompt: Prompt,
   context: ComposerSubmission["context"],
+  text: string,
   alternate: boolean,
 ): ComposerSubmission | undefined {
-  const text = prompt.map((part) => ("content" in part ? part.content : "")).join("")
   const mode = input.mode()
   if (mode === "shell" && !text.trim()) return
   const images = prompt.filter((part): part is ImageAttachmentPart => part.type === "image")
@@ -298,14 +327,11 @@ async function sendShell(session: ComposerSession, value: ComposerSubmission) {
 }
 
 function findCommand(commands: ReturnType<ComposerSubmitInput["commands"]>, text: string) {
-  if (!text.startsWith("/")) return
-  const [name, ...arguments_] = text.split(" ")
-  const command = name.slice(1)
-  if (!commands?.some((item) => item.name === command)) return
-  return { command, arguments: arguments_.join(" ") }
+  const parsed = parseSlashCommand(text)
+  if (!parsed || !commands?.some((item) => item.name === parsed.name)) return
+  return { command: parsed.name, arguments: parsed.input }
 }
 
-
 async function sendCommand(
   session: ComposerSession,
   value: ComposerSubmission,
@@ -390,7 +416,10 @@ async function sendPrompt(
 
 async function buildSubmissionRequest(session: ComposerSession, value: ComposerSubmission) {
   const images = await Promise.all(
-    value.images.map(async (attachment) => ({ ...attachment, dataUrl: await blobDataUrl(attachment.blob, attachment.mime) })),
+    value.images.map(async (attachment) => ({
+      ...attachment,
+      dataUrl: await blobDataUrl(attachment.blob, attachment.mime),
+    })),
   )
   return buildPromptRequest({
     prompt: value.prompt,
diff --git a/packages/app/src/home/sessions/command-palette.tsx b/packages/app/src/home/sessions/command-palette.tsx
index ec4deb74673..6e690f92f94 100644
--- a/packages/app/src/home/sessions/command-palette.tsx
+++ b/packages/app/src/home/sessions/command-palette.tsx
@@ -47,7 +47,7 @@ export function HomeCommandPalette(props: {
     state.cleanup = undefined
     dialog.close()
     if (item.type === "command") {
-      item.option?.onSelect?.("palette")
+      void item.option?.onSelect?.("palette")
       return
     }
     if (item.type === "session") props.onSelectSession(item)
diff --git a/packages/app/src/runtime/i18n/en.ts b/packages/app/src/runtime/i18n/en.ts
index a8f199f2669..ecba2b01850 100644
--- a/packages/app/src/runtime/i18n/en.ts
+++ b/packages/app/src/runtime/i18n/en.ts
@@ -151,6 +151,8 @@ export const dict = {
   "command.session.compact.description": "Summarize the session to reduce context size",
   "command.session.fork": "Fork from message",
   "command.session.fork.description": "Create a new session from a previous message",
+  "command.session.btw": "Ask a side question",
+  "command.session.btw.description": "Get a one-shot answer without adding to the conversation",
   "command.session.export": "Export session",
   "command.session.export.description": "Export the full session transcript as JSON",
   "command.session.import": "Import session",
@@ -756,6 +758,7 @@ export const dict = {
   "session.tab.browser": "Browser",
   "session.tab.add": "Add tab",
   "session.tab.context": "Context",
+  "session.tab.btw": "/btw",
   "session.tab.unknown": "Unknown Session",
   "session.panel.reviewAndFiles": "Review and files",
   "session.error.notFound": "This session cannot be found",
@@ -933,6 +936,10 @@ export const dict = {
   "common.dismiss": "Dismiss",
   "common.moreCountSuffix": " (+{{count}} more)",
   "common.requestFailed": "Request failed",
+  "session.btw.questionRequired": "Add a question after /btw",
+  "session.btw.error": "Couldn’t answer that question",
+  "session.btw.retry": "Retry",
+  "session.btw.copy": "Copy answer",
   "common.moreOptions": "More options",
   "common.learnMore": "Learn more",
   "common.rename": "Rename",
diff --git a/packages/app/src/session/btw/model.ts b/packages/app/src/session/btw/model.ts
new file mode 100644
index 00000000000..606dae5689f
--- /dev/null
+++ b/packages/app/src/session/btw/model.ts
@@ -0,0 +1,114 @@
+import { createEffect, onCleanup } from "solid-js"
+import { createStore } from "solid-js/store"
+import { useLanguage } from "@/runtime/i18n/language"
+import { useServerSDK } from "@/runtime/server/client"
+import { useCommand } from "@/shell/commands/command"
+import { showToast } from "@/shell/notifications/toast"
+import { SESSION_BTW_TAB } from "@/session/helpers"
+import type { SessionModel } from "../model"
+
+const instructions = [
+  "The user is asking a quick side question about the conversation so far.",
+  "Answer directly and concisely in markdown from what you already know.",
+  "Do not call any tools and do not take any actions.",
+].join(" ")
+
+const empty = {
+  question: "",
+  answer: "",
+  error: false,
+  pending: false,
+}
+
+export function createSessionBtw(session: SessionModel) {
+  const command = useCommand()
+  const language = useLanguage()
+  const server = useServerSDK()
+  const [states, setStates] = createStore<Record<string, typeof empty>>({})
+  const requests = new Map<string, number>()
+  const controllers = new Map<string, AbortController>()
+  const state = () => states[session.identity.sessionKey()] ?? empty
+
+  createEffect(() => {
+    const key = session.identity.sessionKey()
+    onCleanup(() => {
+      const controller = controllers.get(key)
+      if (!controller) return
+      controller.abort()
+      controllers.delete(key)
+      if (states[key]?.pending) setStates(key, { pending: false, error: true })
+    })
+  })
+
+  const open = () => {
+    session.layout.view().reviewPanel.open()
+    const tabs = session.layout.tabs()
+    if (tabs.active() !== SESSION_BTW_TAB) tabs.open(SESSION_BTW_TAB)
+  }
+  const ask = (value?: string) => {
+    const question = value?.trim()
+    if (!question) {
+      showToast({ title: language.t("session.btw.questionRequired") })
+      return
+    }
+    open()
+    const sessionID = session.identity.sessionID()
+    if (!sessionID) return
+
+    const key = session.identity.sessionKey()
+    const request = (requests.get(key) ?? 0) + 1
+    requests.set(key, request)
+    controllers.get(key)?.abort()
+    const controller = new AbortController()
+    controllers.set(key, controller)
+    const owner = session.ownership.capture()
+    setStates(key, { question, answer: "", error: false, pending: true })
+    return server.api.session
+      .generate(
+        {
+          sessionID,
+          prompt: [instructions, question].join("\n\n"),
+        },
+        { signal: controller.signal },
+      )
+      .then((result) => {
+        owner.run(() => {
+          if (requests.get(key) !== request) return
+          setStates(key, { answer: result.text.trim(), pending: false })
+        })
+      })
+      .catch(() => {
+        owner.run(() => {
+          if (controller.signal.aborted || requests.get(key) !== request) return
+          setStates(key, { error: true, pending: false })
+        })
+      })
+      .finally(() => {
+        if (controllers.get(key) === controller) controllers.delete(key)
+      })
+  }
+
+  command.register("session.btw", () => [
+    {
+      id: "session.btw",
+      title: language.t("command.session.btw"),
+      description: language.t("command.session.btw.description"),
+      category: language.t("command.category.session"),
+      slash: "btw",
+      slashArguments: true,
+      hidden: true,
+      disabled: !session.isDesktop(),
+      onSelect: (_source, input) => ask(input),
+    },
+  ])
+
+  return {
+    answer: () => state().answer,
+    error: () => state().error,
+    pending: () => state().pending,
+    question: () => state().question,
+    retry: () => ask(state().question),
+  }
+}
+
+export type SessionBtwModel = ReturnType<typeof createSessionBtw>
diff --git a/packages/app/src/session/btw/panel.tsx b/packages/app/src/session/btw/panel.tsx
new file mode 100644
index 00000000000..5b17d41b98a
--- /dev/null
+++ b/packages/app/src/session/btw/panel.tsx
@@ -0,0 +1,80 @@
+import { createEffect, createSignal, Match, Show, Switch } from "solid-js"
+import { Button } from "@opencode/ui/button"
+import { Icon } from "@opencode/ui/icon"
+import { IconButton } from "@opencode/ui/icon-button"
+import { ScrollView } from "@opencode/ui/scroll-view"
+import { TextShimmer } from "@opencode/ui/text-shimmer"
+import { Tooltip } from "@opencode/ui/tooltip"
+import { Markdown } from "@opencode/session-ui/markdown"
+import { useLanguage } from "@/runtime/i18n/language"
+import { usePlatform } from "@/runtime/platform/platform"
+import { showToast } from "@/shell/notifications/toast"
+import type { SessionBtwModel } from "./model"
+
+export function SessionBtwPanel(props: { btw: SessionBtwModel }) {
+  const language = useLanguage()
+  const platform = usePlatform()
+  const [copied, setCopied] = createSignal(false)
+
+  createEffect(() => {
+    props.btw.answer()
+    setCopied(false)
+  })
+
+  const copy = () => {
+    const answer = props.btw.answer()
+    if (!answer) return
+    void (platform.writeClipboardText?.(answer) ?? navigator.clipboard.writeText(answer)).then(
+      () => setCopied(true),
+      () => showToast({ title: language.t("common.requestFailed") }),
+    )
+  }
+
+  return (
+    <div class="flex h-full min-h-0 flex-col bg-v2-background-bg-base" data-slot="session-btw-panel">
+      <div class="flex shrink-0 items-start justify-between gap-3 border-b border-v2-border-border-base px-5 py-4">
+        <div class="min-w-0 text-13-regular text-text-weak">{props.btw.question()}</div>
+        <Show when={props.btw.answer()}>
+          <Tooltip value={copied() ? language.t("common.copied") : language.t("session.btw.copy")}>
+            <IconButton
+              size="small"
+              variant="ghost-muted"
+              icon={<Icon name={copied() ? "check" : "outline-copy"} />}
+              aria-label={copied() ? language.t("common.copied") : language.t("session.btw.copy")}
+              onClick={copy}
+            />
+          </Tooltip>
+        </Show>
+      </div>
+
+      <div class="relative min-h-0 flex-1">
+        <Switch>
+          <Match when={props.btw.pending()}>
+            <div
+              data-component="session-working"
+              role="status"
+              class="flex h-9 items-center px-5 pt-3 text-[13px] font-[530] leading-text-compact"
+            >
+              <TextShimmer text={language.t("session.timeline.working")} active />
+            </div>
+          </Match>
+          <Match when={props.btw.error()}>
+            <div class="flex h-full flex-col items-center justify-center gap-3 px-8 pb-24 text-center">
+              <div class="text-13-regular text-text-weak">{language.t("session.btw.error")}</div>
+              <Button size="small" variant="outline" onClick={props.btw.retry}>
+                {language.t("session.btw.retry")}
+              </Button>
+            </div>
+          </Match>
+          <Match when={props.btw.answer()}>
+            <ScrollView class="absolute inset-0">
+              <div class="px-5 py-4 pb-8">
+                <Markdown text={props.btw.answer()} class="text-14-regular" />
+              </div>
+            </ScrollView>
+          </Match>
+        </Switch>
+      </div>
+    </div>
+  )
+}
diff --git a/packages/app/src/session/files/session-side-panel.tsx b/packages/app/src/session/files/session-side-panel.tsx
index a48ace00b86..02ab8468705 100644
--- a/packages/app/src/session/files/session-side-panel.tsx
+++ b/packages/app/src/session/files/session-side-panel.tsx
@@ -37,6 +37,7 @@ import { useSettings } from "@/settings/model"
 import { createFileTabListSync } from "@/session/files/file-tab-scroll"
 import {
   SESSION_OPEN_FILE_TAB,
+  SESSION_BTW_TAB,
   isSessionBrowserTab,
   sessionBrowserTab,
   createOpenSessionFileTab,
@@ -74,6 +75,7 @@ export function SessionSidePanel(props: {
   size: Sizing
   stacked?: boolean
   browser: ReturnType<typeof createSessionBrowser>
+  btwPanel: () => JSX.Element
 }) {
   const layout = useLayout()
   const settings = useSettings()
@@ -227,7 +229,7 @@ export function SessionSidePanel(props: {
   })
   const fileBrowserVisible = createMemo(() => {
     const active = activeTab()
-    return active !== "review" && active !== "context" && active !== "empty" && !isSessionBrowserTab(active)
+    return active === SESSION_OPEN_FILE_TAB || active === activeFileTab()
   })
   const openFileKeybind = createMemo(() => command.keybindParts("file.open"))
   const openBrowserKeybind = createMemo(() => command.keybindParts("browser.open"))
@@ -385,6 +387,14 @@ export function SessionSidePanel(props: {
                                   />
                                 }
                               >
+                                <Match when={tab === SESSION_BTW_TAB}>
+                                  <SortableTab tab={tab} index={tabs().all().indexOf(tab)} onTabClose={tabs().close}>
+                                    <div class="flex items-center gap-1.5">
+                                      <Icon name="bubble-5" size="small" />
+                                      <span>{language.t("session.tab.btw")}</span>
+                                    </div>
+                                  </SortableTab>
+                                </Match>
                                 <Match when={isSessionBrowserTab(tab)}>
                                   <Show when={props.browser.tabs().find((item) => sessionBrowserTab(item.id) === tab)}>
                                     {(item) => (
@@ -583,6 +593,12 @@ export function SessionSidePanel(props: {
                         </Tabs.Content>
                       </Show>
 
+                      <Show when={activeTab() === SESSION_BTW_TAB}>
+                        <Tabs.Content value={SESSION_BTW_TAB} class="flex h-full min-h-0 flex-col overflow-hidden">
+                          {props.btwPanel()}
+                        </Tabs.Content>
+                      </Show>
+
                       <Show when={props.browser.opened()}>
                         <div
                           id={browserTabPanelID}
diff --git a/packages/app/src/session/helpers.test.ts b/packages/app/src/session/helpers.test.ts
index 6ecca230775..dad25851940 100644
--- a/packages/app/src/session/helpers.test.ts
+++ b/packages/app/src/session/helpers.test.ts
@@ -2,6 +2,7 @@ import { describe, expect, test } from "bun:test"
 import { createMemo, createRoot } from "solid-js"
 import { createStore } from "solid-js/store"
 import {
+  SESSION_BTW_TAB,
   SESSION_BROWSER_TAB,
   sessionBrowserTab,
   SESSION_OPEN_FILE_TAB,
@@ -236,6 +237,24 @@ describe("createSessionTabs", () => {
     })
   })
 
+  test("exposes the BTW tab without treating it as a file tab", () => {
+    createRoot((dispose) => {
+      const tabs = createMemo(() => ({ active: () => SESSION_BTW_TAB, all: () => [SESSION_BTW_TAB] }))
+      const result = createSessionTabs({
+        tabs,
+        pathFromTab: () => undefined,
+        normalizeTab: (tab) => tab,
+      })
+
+      expect(result.panelTabs()).toEqual([SESSION_BTW_TAB])
+      expect(result.openedTabs()).toEqual([])
+      expect(result.activeTab()).toBe(SESSION_BTW_TAB)
+      expect(result.activeFileTab()).toBeUndefined()
+      expect(result.closableTab()).toBe(SESSION_BTW_TAB)
+      dispose()
+    })
+  })
+
   test("exposes one browser tab without treating it as a file tab", () => {
     createRoot((dispose) => {
       const tabs = createMemo(() => ({ active: () => SESSION_BROWSER_TAB, all: () => [SESSION_BROWSER_TAB] }))
diff --git a/packages/app/src/session/helpers.ts b/packages/app/src/session/helpers.ts
index f337725200b..b5438942e49 100644
--- a/packages/app/src/session/helpers.ts
+++ b/packages/app/src/session/helpers.ts
@@ -2,10 +2,11 @@ import { batch, createMemo, onCleanup, onMount, type Accessor } from "solid-js"
 import { createStore } from "solid-js/store"
 import { makeEventListener } from "@solid-primitives/event-listener"
 import { same } from "@/runtime/persistence/equality"
-import { isSessionBrowserTab, SESSION_OPEN_FILE_TAB } from "@/shell/state/session-tabs"
+import { isSessionBrowserTab, SESSION_BTW_TAB, SESSION_OPEN_FILE_TAB } from "@/shell/state/session-tabs"
 
 export {
   SESSION_BROWSER_TAB,
+  SESSION_BTW_TAB,
   SESSION_OPEN_FILE_TAB,
   sessionBrowserTab,
   isSessionBrowserTab,
@@ -63,13 +64,17 @@ export const createSessionTabs = (input: TabsInput) => {
     { equals: same },
   )
   const openedTabs = createMemo(
-    () => panelTabs().filter((tab) => tab !== SESSION_OPEN_FILE_TAB && !isSessionBrowserTab(tab)),
+    () =>
+      panelTabs().filter(
+        (tab) => tab !== SESSION_OPEN_FILE_TAB && tab !== SESSION_BTW_TAB && !isSessionBrowserTab(tab),
+      ),
     emptyTabs,
     { equals: same },
   )
   const activeTab = createMemo(() => {
     const active = input.tabs().active()
     if (active === "context") return active
+    if (active === SESSION_BTW_TAB) return active
     if (active === SESSION_OPEN_FILE_TAB && openFileOpen()) return active
     if (active && isSessionBrowserTab(active) && browser()) return active
     if (active === "review" && review()) return active
@@ -89,6 +94,7 @@ export const createSessionTabs = (input: TabsInput) => {
   const closableTab = createMemo<string | undefined>(() => {
     const active = activeTab()
     if (active === "context") return active
+    if (active === SESSION_BTW_TAB) return active
     if (active === SESSION_OPEN_FILE_TAB && openFileOpen()) return active
     if (active && isSessionBrowserTab(active) && browser()) return active
     if (!openedTabs().includes(active)) return
diff --git a/packages/app/src/session/review/view.tsx b/packages/app/src/session/review/view.tsx
index 783c74d200e..e2e81013609 100644
--- a/packages/app/src/session/review/view.tsx
+++ b/packages/app/src/session/review/view.tsx
@@ -14,6 +14,8 @@ import { ReviewPanel } from "./panel"
 import { SessionReviewTab } from "./review-tab"
 import type { ChangeMode, SessionReviewModel } from "./model"
 import type { createSessionBrowser } from "../browser/model"
+import type { SessionBtwModel } from "../btw/model"
+import { SessionBtwPanel } from "../btw/panel"
 
 const MobilePanelDrawer = lazy(async () => {
   const { MobilePanelDrawer } = await import("@/shell/mobile-panel-drawer")
@@ -127,6 +129,7 @@ export function SessionMobileReview(props: { review: SessionReviewModel }) {
 export function SessionDesktopReview(props: {
   review: SessionReviewModel
   browser: ReturnType<typeof createSessionBrowser>
+  btw: SessionBtwModel
   present?: boolean
 }) {
   return (
@@ -153,6 +156,7 @@ export function SessionDesktopReview(props: {
         size={props.review.screen.size}
         stacked={props.review.screen.side.layout().stacked}
         browser={props.browser}
+        btwPanel={() => <SessionBtwPanel btw={props.btw} />}
       />
     </Suspense>
   )
diff --git a/packages/app/src/session/screen.tsx b/packages/app/src/session/screen.tsx
index 8e048a272f0..81d76c143c2 100644
--- a/packages/app/src/session/screen.tsx
+++ b/packages/app/src/session/screen.tsx
@@ -39,6 +39,7 @@ import { createAnimatedPresence } from "@/runtime/animated-presence"
 import { createSessionBrowser } from "./browser/model"
 import { createTimelineCache } from "./timeline/cache"
 import { ArtifactMarkdownProvider, ArtifactOpenerProvider } from "./files/open-artifact"
+import { createSessionBtw } from "./btw/model"
 
 const SessionMobileFiles = lazy(async () => {
   const { SessionMobileFiles } = await import("./files/session-mobile-files")
@@ -71,6 +72,7 @@ function SessionScreenContent(props: { session: SessionModel; browser: ReturnTyp
     return info ? projectForSession(info, server.ctx.sync.data.project) : undefined
   })
   const isDesktop = session.isDesktop
+  const btw = createSessionBtw(session)
   const screen = createSessionScreenLayout(session)
   const timeline = createSessionTimelineInteraction(session)
   const timelineSearch = createTimelineSearchController({
@@ -451,7 +453,12 @@ function SessionScreenContent(props: { session: SessionModel; browser: ReturnTyp
                         setStore("sideReviewPresent", false)
                       }}
                     >
-                      <SessionDesktopReview review={review} browser={browser} present={store.sideReviewPresent} />
+                      <SessionDesktopReview
+                        review={review}
+                        browser={browser}
+                        btw={btw}
+                        present={store.sideReviewPresent}
+                      />
                     </div>
                   </Show>
                 </div>
diff --git a/packages/app/src/shell/commands/command.tsx b/packages/app/src/shell/commands/command.tsx
index 4ce001a1a35..22368d31d87 100644
--- a/packages/app/src/shell/commands/command.tsx
+++ b/packages/app/src/shell/commands/command.tsx
@@ -88,11 +88,12 @@ export interface CommandOption {
   category?: string
   keybind?: KeybindConfig
   slash?: string
+  slashArguments?: boolean
   suggested?: boolean
   disabled?: boolean
   hidden?: boolean
   when?: (event: KeyboardEvent) => boolean
-  onSelect?: (source?: "palette" | "keybind" | "slash") => void
+  onSelect?: (source?: "palette" | "keybind" | "slash", input?: string) => void | Promise<void>
   onHighlight?: () => (() => void) | void
 }
 
@@ -389,9 +390,9 @@ export const { use: useCommand, provider: CommandProvider } = createSimpleContex
       return map
     })
 
-    const run = (id: string, source?: CommandSource) => {
+    const run = (id: string, source?: CommandSource, input?: string) => {
       const option = optionMap().get(id)
-      option?.onSelect?.(source)
+      return option?.onSelect?.(source, input)
     }
 
     const showPalette = () => {
@@ -420,7 +421,7 @@ export const { use: useCommand, provider: CommandProvider } = createSimpleContex
       if (!option) return
       event.preventDefault()
       event.stopPropagation()
-      option.onSelect?.("keybind")
+      void option.onSelect?.("keybind")
     }
 
     onMount(() => {
@@ -454,8 +455,8 @@ export const { use: useCommand, provider: CommandProvider } = createSimpleContex
 
     return {
       register,
-      trigger(id: string, source?: CommandSource) {
-        run(id, source)
+      trigger(id: string, source?: CommandSource, input?: string) {
+        return run(id, source, input)
       },
       keybind(id: string) {
         const config = keybindConfig(id)
diff --git a/packages/app/src/shell/commands/palette.ts b/packages/app/src/shell/commands/palette.ts
index fa886c4a5bd..998b2c1ca02 100644
--- a/packages/app/src/shell/commands/palette.ts
+++ b/packages/app/src/shell/commands/palette.ts
@@ -166,7 +166,7 @@ export function createCommandPaletteModel(props: { filesOnly?: () => boolean; on
     state.cleanup = undefined
     dialog.close()
     if (item.type === "command") {
-      item.option?.onSelect?.("palette")
+      void item.option?.onSelect?.("palette")
       return
     }
     if (item.type === "session") {
diff --git a/packages/app/src/shell/state/layout.test.ts b/packages/app/src/shell/state/layout.test.ts
index 2470b037e80..e69bf23f28b 100644
--- a/packages/app/src/shell/state/layout.test.ts
+++ b/packages/app/src/shell/state/layout.test.ts
@@ -96,7 +96,7 @@ describe("layout persistence", () => {
   test("keeps scoped state and salvages valid tab entries", () => {
     const key = "local\u0000L3Byb2plY3Q/session"
     const value = decode({
-      sessionTabs: { old: { all: ["old"] }, [key]: { all: ["a", null, "a", "b"], active: 12 } },
+      sessionTabs: { old: { all: ["old"] }, [key]: { all: ["a", null, "a", "b", "btw"], active: "btw" } },
       sessionView: { old: { scroll: {} }, [key]: { scroll: {}, reviewOpen: ["a", null, "b"] } },
     })
     expect(value.sessionTabs).toEqual({ [key]: { all: ["a", "b"], active: undefined } })
diff --git a/packages/app/src/shell/state/layout.tsx b/packages/app/src/shell/state/layout.tsx
index 4cf523b55c7..87027d6d07a 100644
--- a/packages/app/src/shell/state/layout.tsx
+++ b/packages/app/src/shell/state/layout.tsx
@@ -18,7 +18,7 @@ import type { ProjectAvatarVariant } from "@opencode/ui/project-avatar"
 import { SessionStateKey } from "@/runtime/server/scope"
 import { createSessionKeyReader, ensureSessionKey, pruneSessionKeys } from "./helpers"
 import { requireServerKey } from "@/shell/routes/session"
-import { closeSessionTab, openSessionTab, previewSessionTab, type SessionTabs } from "./session-tabs"
+import { closeSessionTab, openSessionTab, previewSessionTab, SESSION_BTW_TAB, type SessionTabs } from "./session-tabs"
 
 export { createSessionKeyReader, ensureSessionKey, pruneSessionKeys }
 
@@ -97,8 +97,9 @@ const normalizeSessionTabList = (path: ReturnType<typeof createPathHelpers> | un
 const normalizeStoredSessionTabs = (key: string, tabs: SessionTabs) => {
   const path = sessionPath(key)
   return {
-    all: normalizeSessionTabList(path, tabs.all),
-    active: tabs.active ? normalizeSessionTab(path, tabs.active) : tabs.active,
+    all: normalizeSessionTabList(path, tabs.all).filter((tab) => tab !== SESSION_BTW_TAB),
+    active:
+      tabs.active === SESSION_BTW_TAB ? undefined : tabs.active ? normalizeSessionTab(path, tabs.active) : tabs.active,
   }
 }
 
diff --git a/packages/app/src/shell/state/session-tabs.ts b/packages/app/src/shell/state/session-tabs.ts
index 1f3f0ad5b0f..0f8c4b57558 100644
--- a/packages/app/src/shell/state/session-tabs.ts
+++ b/packages/app/src/shell/state/session-tabs.ts
@@ -1,5 +1,6 @@
 export const SESSION_OPEN_FILE_TAB = "open-file"
 export const SESSION_BROWSER_TAB = "browser"
+export const SESSION_BTW_TAB = "btw"
 export const sessionBrowserTab = (tabID: string) => `${SESSION_BROWSER_TAB}:${tabID}`
 export const isSessionBrowserTab = (tab: string | undefined) =>
   !!tab && (tab === SESSION_BROWSER_TAB || tab.startsWith(`${SESSION_BROWSER_TAB}:`))