openchamber/packages/ui/src/sync/session-actions.ts

/**
 * Session actions — SDK-calling operations for session management.
 * Replaces the action methods from the old useSessionStore.
 */

import type { OpencodeClient, Session, Message, Part } from "@opencode-ai/sdk/v2/client"
import { Binary } from "./binary"
import { useSessionUIStore } from "./session-ui-store"
import { useInputStore } from "./input-store"
import type { ChildStoreManager } from "./child-store"
import { opencodeClient } from "@/lib/opencode/client"
import { useGlobalSessionsStore } from "@/stores/useGlobalSessionsStore"
import { useConfigStore } from "@/stores/useConfigStore"
import { registerSessionDirectory } from "./sync-refs"
import { isSyntheticPart } from "@/lib/messages/synthetic"
import { materializeSessionSnapshots } from "./materialization"
import { stripMessageDiffSnapshots } from "./sanitize"

const MESSAGE_REFETCH_LIMIT = 200
const MESSAGE_REFETCH_SKIP_PARTS = new Set(["patch", "step-start", "step-finish"])
const UNREVERT_REFETCH_ATTEMPTS = 3
const UNREVERT_REFETCH_RETRY_MS = 150

// Reference set by SyncProvider — allows actions to access SDK and stores
let _sdk: OpencodeClient | null = null
let _childStores: ChildStoreManager | null = null
let _getDirectory: () => string = () => ""
let _optimisticAdd: ((input: { sessionID: string; message: Message; parts: Part[] }) => void) | null = null
let _optimisticRemove: ((input: { sessionID: string; messageID: string }) => void) | null = null

const wait = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms))

export function setActionRefs(
  sdk: OpencodeClient,
  childStores: ChildStoreManager,
  getDirectory: () => string,
) {
  _sdk = sdk
  _childStores = childStores
  _getDirectory = getDirectory
}

export function setOptimisticRefs(
  add: (input: { sessionID: string; message: Message; parts: Part[] }) => void,
  remove: (input: { sessionID: string; messageID: string }) => void,
) {
  _optimisticAdd = add
  _optimisticRemove = remove
}

function sdk() {
  if (!_sdk) throw new Error("SDK not initialized — is SyncProvider mounted?")
  return _sdk
}

function dirStore() {
  if (!_childStores) throw new Error("Child stores not initialized")
  const d = _getDirectory()
  if (!d) throw new Error("No current directory")
  return _childStores.ensureChild(d)
}

function dir() {
  return _getDirectory() || undefined
}

function connectionLostError(): Error {
  const { hasEverConnected, lastDisconnectReason } = useConfigStore.getState()
  const suffix = lastDisconnectReason
    ? ` (${lastDisconnectReason})`
    : hasEverConnected
      ? ""
      : " (never connected)"
  return new Error(`Connection lost${suffix}. Please wait for reconnection.`)
}

// Wait briefly for the pipeline to re-establish connection before failing a
// send. Transient reconnects (heartbeat race, WS→SSE fallback, brief network
// blip) otherwise surface as a hard "Connection lost" toast even though the
// pipeline recovers within a second. While waiting, run bounded health probes
// inside the same grace window so stale disconnected state can recover quickly.
const CONNECTION_GRACE_MS = 2000
export async function waitForConnectionOrThrow(): Promise<void> {
  const deadline = Date.now() + CONNECTION_GRACE_MS
  while (Date.now() < deadline) {
    if (useConfigStore.getState().isConnected) return
    const remainingMs = deadline - Date.now()
    if (remainingMs <= 0) break
    if (await useConfigStore.getState().probeConnection({ timeoutMs: Math.min(500, remainingMs) })) return
    const sleepMs = Math.min(100, deadline - Date.now())
    if (sleepMs > 0) {
      await new Promise((resolve) => setTimeout(resolve, sleepMs))
    }
  }
  throw connectionLostError()
}

function getSessionDirectory(sessionId: string): string | undefined {
  return useSessionUIStore.getState().getDirectoryForSession(sessionId) || dir()
}

function getDirectoryStore(directory?: string) {
  if (!_childStores) throw new Error("Child stores not initialized")
  const resolvedDirectory = directory || _getDirectory()
  if (!resolvedDirectory) throw new Error("No current directory")
  return _childStores.ensureChild(resolvedDirectory)
}

function getSessionReplyClient(sessionId?: string): OpencodeClient {
  const directory = sessionId
    ? useSessionUIStore.getState().getDirectoryForSession(sessionId)
    : null
  if (directory) {
    return opencodeClient.getScopedSdkClient(directory)
  }
  return sdk()
}

function resolveDirectoryForBlockingRequest(
  type: "permission" | "question",
  sessionId: string,
  requestId: string,
): string | null {
  const stores = _childStores
  if (!stores || !requestId) {
    return null
  }

  for (const [directory, store] of stores.children) {
    const state = store.getState()
    const requestMap = type === "permission" ? state.permission : state.question
    for (const requests of Object.values(requestMap) as Array<Array<{ id: string }> | undefined>) {
      if (requests?.some((request) => request.id === requestId)) {
        return directory
      }
    }
  }

  const sessionDirectory = useSessionUIStore.getState().getDirectoryForSession(sessionId)
  if (sessionDirectory) {
    return sessionDirectory
  }

  for (const [directory, store] of stores.children) {
    const state = store.getState()
    if (
      state.session.some((session) => session.id === sessionId)
      || Object.prototype.hasOwnProperty.call(state.message, sessionId)
      || Object.prototype.hasOwnProperty.call(state.session_status ?? {}, sessionId)
      || Object.prototype.hasOwnProperty.call(state.permission ?? {}, sessionId)
      || Object.prototype.hasOwnProperty.call(state.question ?? {}, sessionId)
    ) {
      return directory
    }
  }

  return null
}

function getRequestReplyClient(
  type: "permission" | "question",
  sessionId: string,
  requestId: string,
): OpencodeClient {
  const requestDirectory = resolveDirectoryForBlockingRequest(type, sessionId, requestId)
  if (requestDirectory) {
    return opencodeClient.getScopedSdkClient(requestDirectory)
  }
  return getSessionReplyClient(sessionId)
}

// ---------------------------------------------------------------------------
// Session CRUD
// ---------------------------------------------------------------------------

export async function createSession(
  title?: string,
  directoryOverride?: string | null,
  parentID?: string | null,
): Promise<Session | null> {
  try {
    const result = await sdk().session.create({
      directory: directoryOverride ?? dir(),
      title,
      parentID: parentID ?? undefined,
    })
    const session = result.data
    if (!session) return null

      const sessionDirectory = (session as { directory?: string }).directory ?? directoryOverride ?? null
      // Pre-populate routing index so SSE events arriving before session.created
      // can be routed to the correct child store
      if (sessionDirectory) {
        registerSessionDirectory(session.id, sessionDirectory)
      }
      useSessionUIStore.getState().setCurrentSession(session.id, sessionDirectory)
      useSessionUIStore.getState().markSessionAsOpenChamberCreated(session.id)
      useGlobalSessionsStore.getState().upsertSession(session)
      return session
  } catch (error) {
    console.error("[session-actions] createSession failed", error)
    return null
  }
}

/** Optimistically remove a session from the child store list. Returns previous list for rollback. */
function optimisticRemoveSession(sessionId: string, directory?: string): Session[] | null {
  const store = getDirectoryStore(directory)
  const current = store.getState()
  const sessions = [...current.session]
  const result = Binary.search(sessions, sessionId, (s) => s.id)
  if (result.found) {
    const snapshot = current.session
    sessions.splice(result.index, 1)
    store.setState({ session: sessions })
    return snapshot
  }
  return null
}

// eslint-disable-next-line @typescript-eslint/no-unused-vars
export async function deleteSession(sessionId: string, _options?: Record<string, unknown>): Promise<boolean> {
  const sessionDirectory = getSessionDirectory(sessionId)
  // Remove from UI immediately, rollback on error
  let snapshot = optimisticRemoveSession(sessionId, sessionDirectory)
  let removedFromDir: string | null = snapshot ? (sessionDirectory ?? null) : null

  // If the session wasn't in the resolved directory (e.g. archived session
  // whose original child store was disposed), search all child stores.
  if (!snapshot && _childStores) {
    for (const [dir, store] of _childStores.children.entries()) {
      const current = store.getState()
      const sessions = [...current.session]
      const result = Binary.search(sessions, sessionId, (s) => s.id)
      if (result.found) {
        snapshot = current.session
        sessions.splice(result.index, 1)
        store.setState({ session: sessions })
        removedFromDir = dir
        break
      }
    }
  }

  const ui = useSessionUIStore.getState()
  if (ui.currentSessionId === sessionId) {
    ui.setCurrentSession(null)
  }
  try {
    await sdk().session.delete({ sessionID: sessionId, directory: sessionDirectory })
    useGlobalSessionsStore.getState().removeSessions([sessionId])
    return true
  } catch (error) {
    console.error("[session-actions] deleteSession failed", error)
    if (snapshot && removedFromDir) {
      try {
        getDirectoryStore(removedFromDir).setState({ session: snapshot })
      } catch {
        // child store may have been disposed since — ignore rollback
      }
    }
    return false
  }
}

/** Delete a session specifying which directory it lives in. Used by agent groups for cross-directory deletes. */
export async function deleteSessionInDirectory(sessionId: string, directory: string): Promise<boolean> {
  if (!_childStores) return false
  const store = _childStores.ensureChild(directory)
  const current = store.getState()
  const sessions = [...current.session]
  const result = Binary.search(sessions, sessionId, (s) => s.id)
  let snapshot: Session[] | null = null
  if (result.found) {
    snapshot = current.session
    sessions.splice(result.index, 1)
    store.setState({ session: sessions })
  }
  const ui = useSessionUIStore.getState()
  if (ui.currentSessionId === sessionId) ui.setCurrentSession(null)
  try {
    await sdk().session.delete({ sessionID: sessionId, directory })
    useGlobalSessionsStore.getState().removeSessions([sessionId])
    return true
  } catch (error) {
    console.error("[session-actions] deleteSessionInDirectory failed", error)
    if (snapshot) store.setState({ session: snapshot })
    return false
  }
}

export async function archiveSession(sessionId: string): Promise<boolean> {
  const sessionDirectory = getSessionDirectory(sessionId)
  const snapshot = optimisticRemoveSession(sessionId, sessionDirectory)
  const ui = useSessionUIStore.getState()
  if (ui.currentSessionId === sessionId) {
    ui.setCurrentSession(null)
  }
  try {
    const archivedAt = Date.now()
    await sdk().session.update({ sessionID: sessionId, directory: sessionDirectory, time: { archived: archivedAt } })
    useGlobalSessionsStore.getState().archiveSessions([sessionId], archivedAt)
    return true
  } catch (error) {
    console.error("[session-actions] archiveSession failed", error)
    if (snapshot) getDirectoryStore(sessionDirectory).setState({ session: snapshot })
    return false
  }
}

export async function updateSessionTitle(sessionId: string, title: string): Promise<void> {
  const sessionDirectory = getSessionDirectory(sessionId)
  const result = await sdk().session.update({ sessionID: sessionId, directory: sessionDirectory, title })
  if (result.data) {
    useGlobalSessionsStore.getState().upsertSession(result.data)
  }
}

export async function shareSession(sessionId: string): Promise<Session | null> {
  const sessionDirectory = getSessionDirectory(sessionId)
  const result = await sdk().session.share({ sessionID: sessionId, directory: sessionDirectory })
  if (result.data) {
    useGlobalSessionsStore.getState().upsertSession(result.data)
  }
  return result.data ?? null
}

export async function unshareSession(sessionId: string): Promise<Session | null> {
  const sessionDirectory = getSessionDirectory(sessionId)
  const result = await sdk().session.unshare({ sessionID: sessionId, directory: sessionDirectory })
  if (result.data) {
    useGlobalSessionsStore.getState().upsertSession(result.data)
  }
  return result.data ?? null
}

// ---------------------------------------------------------------------------
// Optimistic message send — insert user message before API call, rollback on error
// ---------------------------------------------------------------------------

// ID generator matching OpenCode's Identifier.ascending format.
// Uses BigInt(timestamp) * 0x1000 + counter, encoded as 6 hex bytes + random base62.
// This ensures client-generated IDs sort correctly with server-generated ones.
let lastIdTimestamp = 0
let idCounter = 0

function ascendingId(prefix: string): string {
  const now = Date.now()
  if (now !== lastIdTimestamp) {
    lastIdTimestamp = now
    idCounter = 0
  }
  idCounter += 1

  const value = BigInt(now) * BigInt(0x1000) + BigInt(idCounter)
  const bytes = new Uint8Array(6)
  for (let i = 0; i < 6; i++) {
    bytes[i] = Number((value >> BigInt(40 - 8 * i)) & BigInt(0xff))
  }

  let hex = ""
  for (let i = 0; i < bytes.length; i++) {
    hex += bytes[i].toString(16).padStart(2, "0")
  }

  const chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
  let rand = ""
  for (let i = 0; i < 14; i++) {
    rand += chars[Math.floor(Math.random() * 62)]
  }

  return `${prefix}_${hex}${rand}`
}

/**
 * Wraps an async send operation with optimistic user-message insertion.
 * Uses useSync()'s optimistic infrastructure — message + parts are inserted
 * into the store AND registered in the shadow Map. mergeOptimisticPage
 * handles deduplication when the server echoes back the real message.
 */
export async function optimisticSend(input: {
  sessionId: string
  content: string
  providerID: string
  modelID: string
  agent?: string
  files?: Array<{ type: "file"; mime: string; url: string; filename: string }>
  /** The actual API call — receives the optimistic messageID so the server can use the same ID */
  send: (messageID: string) => Promise<void>
}): Promise<void> {
  if (!_optimisticAdd || !_optimisticRemove) {
    throw new Error("Optimistic refs not set — is useSync() mounted?")
  }

  await waitForConnectionOrThrow()

  const store = dirStore()
  const messageID = ascendingId("msg")
  const textPartId = ascendingId("prt")

  const optimisticParts: Part[] = [
    { id: textPartId, type: "text", text: input.content } as Part,
  ]
  if (input.files) {
    for (const f of input.files) {
      optimisticParts.push({ id: ascendingId("prt"), type: "file", mime: f.mime, url: f.url, filename: f.filename } as Part)
    }
  }

  const optimisticMessage = {
    id: messageID,
    role: "user" as const,
    sessionID: input.sessionId,
    parentID: "",
    modelID: input.modelID,
    providerID: input.providerID,
    system: "",
    agent: input.agent ?? "",
    model: `${input.providerID}/${input.modelID}`,
    metadata: {} as Record<string, unknown>,
    time: { created: Date.now(), completed: 0 },
  } as unknown as Message

  // Insert into store + register in shadow Map (for mergeOptimisticPage cleanup)
  _optimisticAdd({
    sessionID: input.sessionId,
    message: optimisticMessage,
    parts: optimisticParts,
  })

  // Set busy status
  const current = store.getState()
  store.setState({
    session_status: {
      ...current.session_status,
      [input.sessionId]: { type: "busy" as const },
    },
  })

  try {
    await input.send(messageID)
  } catch (error) {
    // Rollback via optimistic infrastructure
    _optimisticRemove({
      sessionID: input.sessionId,
      messageID,
    })
    const s = store.getState()
    store.setState({
      session_status: {
        ...s.session_status,
        [input.sessionId]: { type: "idle" as const },
      },
    })
    throw error
  }
}

// ---------------------------------------------------------------------------
// Abort
// ---------------------------------------------------------------------------

export async function abortCurrentOperation(sessionId: string): Promise<void> {
  try {
    await sdk().session.abort({ sessionID: sessionId, directory: dir() })
  } catch (error) {
    console.error("[session-actions] abort failed", error)
  }
}

// ---------------------------------------------------------------------------
// Permissions
// ---------------------------------------------------------------------------

export async function respondToPermission(
  sessionId: string,
  requestId: string,
  response: "once" | "always" | "reject",
): Promise<void> {
  await waitForConnectionOrThrow()
  const directory = resolveDirectoryForBlockingRequest("permission", sessionId, requestId)
    || getSessionDirectory(sessionId)
    || dir()
  const result = await getRequestReplyClient("permission", sessionId, requestId).permission.reply({
    requestID: requestId,
    reply: response,
    ...(directory ? { directory } : {}),
  })
  if (!result.data) {
    throw new Error("Permission reply failed")
  }
}

export async function dismissPermission(
  sessionId: string,
  requestId: string,
): Promise<void> {
  await waitForConnectionOrThrow()
  const directory = resolveDirectoryForBlockingRequest("permission", sessionId, requestId)
    || getSessionDirectory(sessionId)
    || dir()
  const result = await getRequestReplyClient("permission", sessionId, requestId).permission.reply({
    requestID: requestId,
    reply: "reject",
    ...(directory ? { directory } : {}),
  })
  if (!result.data) {
    throw new Error("Permission dismissal failed")
  }
}

// ---------------------------------------------------------------------------
// Questions
// ---------------------------------------------------------------------------

export async function respondToQuestion(
  sessionId: string,
  requestId: string,
  answers: string[] | string[][],
): Promise<void> {
  await waitForConnectionOrThrow()
  const directory = resolveDirectoryForBlockingRequest("question", sessionId, requestId)
    || getSessionDirectory(sessionId)
    || dir()
  const result = await getRequestReplyClient("question", sessionId, requestId).question.reply({
    requestID: requestId,
    answers: answers as Array<Array<string>>,
    ...(directory ? { directory } : {}),
  })
  if (!result.data) {
    throw new Error("Question reply failed")
  }
}

export async function rejectQuestion(
  sessionId: string,
  requestId: string,
): Promise<void> {
  await waitForConnectionOrThrow()
  const directory = resolveDirectoryForBlockingRequest("question", sessionId, requestId)
    || getSessionDirectory(sessionId)
    || dir()
  const result = await getRequestReplyClient("question", sessionId, requestId).question.reject({
    requestID: requestId,
    ...(directory ? { directory } : {}),
  })
  if (!result.data) {
    throw new Error("Question rejection failed")
  }
}

// ---------------------------------------------------------------------------
// Message history
// ---------------------------------------------------------------------------

/**
 * Revert to a specific user message.
 *
 * 1. Abort if session is busy
 * 2. Extract text from the target message for prompt restoration
 * 3. Optimistically set revert marker so messages hide immediately
 * 4. Call SDK session.revert() and merge returned session
 * 5. Set pendingInputText so the reverted message text appears in the input
 */
export async function revertToMessage(sessionId: string, messageId: string): Promise<void> {
  const store = dirStore()
  const state = store.getState()

  // Abort if busy before mutating session state
  const status = state.session_status[sessionId]
  if (status && status.type !== "idle") {
    try {
      await sdk().session.abort({ sessionID: sessionId, directory: dir() })
    } catch {
      // ignore abort errors
    }
  }

  // Extract message text for prompt restoration (only non-synthetic text parts —
  // the server adds file content as synthetic text parts that should not be restored)
  const messages = state.message[sessionId] ?? []
  const targetMsg = messages.find((m) => m.id === messageId)
  let messageText = ""
  let submittedFileParts: Array<Record<string, unknown>> = []
  if (targetMsg && targetMsg.role === "user") {
    const parts = state.part[messageId] ?? []
    const textParts = parts.filter((p) => p.type === "text" && !isSyntheticPart(p))
    messageText = textParts
      .map((p: Record<string, unknown>) => (p as { text?: string }).text || (p as { content?: string }).content || "")
      .join("\n")
      .trim()
    // Snapshot file parts for later restoration to the input (line ~626).
    // File parts (type="file") contain url/mime/filename — the file already
    // exists on the server so we record it as a "server" source attachment.
    submittedFileParts = parts.filter((p) => p.type === "file") as Array<Record<string, unknown>>
  }

  // Optimistically set only the revert marker. Keep messages and parts in the
  // local store; visible-message selectors derive the displayed timeline from
  // session.revert. This matches the server model and preserves reverted
  // messages for the restore dock without maintaining a separate shadow copy.
  const prevRevert = (() => {
    const s = state.session.find((s) => s.id === sessionId)
    return (s as Session & { revert?: unknown })?.revert
  })()
  const sessions = [...state.session]
  const sessionIdx = sessions.findIndex((s) => s.id === sessionId)

  const patch: Record<string, unknown> = {}

  if (sessionIdx >= 0) {
    sessions[sessionIdx] = { ...sessions[sessionIdx], revert: { messageID: messageId } } as Session
    patch.session = sessions
  }

  store.setState(patch)

  // Save input store state before mutations — if the API fails we need to
  // roll back both text and attachments to their previous values.
  const prevInputAttachments = [...useInputStore.getState().attachedFiles]
  const prevInputText = useInputStore.getState().pendingInputText
  const prevInputMode = useInputStore.getState().pendingInputMode

  // Restore reverted message text and file attachments to input
  if (messageText) {
    useInputStore.setState({
      pendingInputText: messageText,
      pendingInputMode: "replace" as const,
    })
  }

  // Restore file/image attachments from the target message.
  // Clear existing attachments first — previous revert's attachments
  // must not carry over, even when the current message has no files.
  useInputStore.getState().clearAttachedFiles()
  for (const fp of submittedFileParts) {
      const f = fp as Record<string, unknown>
      const url = typeof f.url === "string" ? f.url : ""
      const mime = typeof f.mime === "string" ? f.mime : "application/octet-stream"
      const filename = typeof f.filename === "string" ? f.filename : "attachment"
      if (url) {
        useInputStore.getState().addRestoredAttachment({ url, mimeType: mime, filename })
      }
    }

  // Call SDK and merge authoritative result into store
  try {
    const result = await sdk().session.revert({ sessionID: sessionId, directory: dir(), messageID: messageId })
    if (result.data) {
      const current = store.getState()
      const updated = [...current.session]
      const idx = updated.findIndex((s) => s.id === sessionId)
      if (idx >= 0) {
        updated[idx] = result.data
        store.setState({ session: updated })
      }
    }
  } catch (err) {
    // Rollback: restore removed messages + revert marker
    const current = store.getState()
    const rollback = [...current.session]
    const idx = rollback.findIndex((s) => s.id === sessionId)
    if (idx >= 0) {
      rollback[idx] = { ...rollback[idx], revert: prevRevert } as Session
    }
    store.setState({
      session: rollback,
    })
    // Rollback input store: restore previous text and attachments
    useInputStore.setState({
      pendingInputText: prevInputText,
      pendingInputMode: prevInputMode,
      attachedFiles: prevInputAttachments,
    })
    throw err
  }
}

export async function refetchSessionMessages(sessionId: string): Promise<void> {
  const store = dirStore()
  const result = await sdk().session.messages({ sessionID: sessionId, directory: dir(), limit: MESSAGE_REFETCH_LIMIT })
  const records = (result.data ?? []).filter((record: { info?: { id?: string } }) => !!record?.info?.id)
  if (records.length === 0) return

  store.setState((state) => {
    const materialized = materializeSessionSnapshots(
      state,
      sessionId,
      records.map((record: { info: Message; parts?: Part[] }) => ({
        info: stripMessageDiffSnapshots(record.info),
        parts: record.parts ?? [],
      })),
      { skipPartTypes: MESSAGE_REFETCH_SKIP_PARTS },
    )
    return { message: materialized.message, part: materialized.part }
  })
}

/**
 * Unrevert — restore all previously reverted messages.
 * Restore all previously reverted messages. Aborts if busy, merges result.
 */
export async function unrevertSession(sessionId: string): Promise<void> {
  const store = dirStore()
  const state = store.getState()
  const previousMessageCount = state.message[sessionId]?.length ?? 0

  // Abort if busy
  const status = state.session_status[sessionId]
  if (status && status.type !== "idle") {
    try {
      await sdk().session.abort({ sessionID: sessionId, directory: dir() })
    } catch {
      // ignore
    }
  }

  const result = await sdk().session.unrevert({ sessionID: sessionId, directory: dir() })
  if (result.data) {
    const current = store.getState()
    const sessions = [...current.session]
    const idx = sessions.findIndex((s) => s.id === sessionId)
    if (idx >= 0) {
      sessions[idx] = result.data
      store.setState({ session: sessions })
    }
  }
  for (let attempt = 0; attempt < UNREVERT_REFETCH_ATTEMPTS; attempt += 1) {
    if (attempt > 0) await wait(UNREVERT_REFETCH_RETRY_MS)
    await refetchSessionMessages(sessionId)
    const nextMessageCount = store.getState().message[sessionId]?.length ?? 0
    if (nextMessageCount > previousMessageCount) return
  }
}

/**
 * Fork from a user message.
 *
 * 1. Extract text from the message for input restoration
 * 2. Call SDK session.fork()
 * 3. Insert the new session into the child store (so sidebar updates immediately)
 * 4. Switch to new session and set pending input text
 */
export async function forkFromMessage(sessionId: string, messageId: string): Promise<void> {
  const store = dirStore()
  const state = store.getState()

  // Extract message text for input restoration (only non-synthetic text parts —
  // the server adds file content as synthetic text parts that should not be restored)
  const parts = state.part[messageId] ?? []
  let messageText = ""
  const textParts = parts.filter((p) => p.type === "text" && !isSyntheticPart(p))
  messageText = textParts
    .map((p: Part) => ((p as Record<string, unknown>).text as string) || ((p as Record<string, unknown>).content as string) || "")
    .join("\n")
    .trim()

  const result = await sdk().session.fork({ sessionID: sessionId, directory: dir(), messageID: messageId })
  if (!result.data) return

  const forkedSession = result.data

  // Insert new session into child store so sidebar updates immediately
  const current = store.getState()
  const sessions = [...current.session]
  const searchResult = Binary.search(sessions, forkedSession.id, (s) => s.id)
  if (!searchResult.found) {
    sessions.splice(searchResult.index, 0, forkedSession)
    store.setState({ session: sessions })
  }

  // Switch to new session
  useSessionUIStore.getState().setCurrentSession(forkedSession.id)

  // Restore forked message text to input
  if (messageText) {
    useInputStore.setState({
      pendingInputText: messageText,
      pendingInputMode: "replace" as const,
    })
  }
}