export * as SessionV2 from "./session"
export * from "./session/schema"

import { DateTime, Effect, Layer, Schema, Context, Stream, Scope } from "effect"
import { ListAnchor } from "@opencode-ai/schema/session"
import { and, asc, desc, eq, gt, isNull, like, lt, or, type SQL } from "drizzle-orm"
import { ProjectV2 } from "./project"
import { WorkspaceV2 } from "./workspace"
import { ModelV2 } from "./model"
import { Location } from "./location"
import { SessionMessage } from "./session/message"
import { Prompt } from "./session/prompt"
import { PromptInput } from "@opencode-ai/schema/prompt-input"
import { EventV2 } from "./event"
import { Database } from "./database/database"
import { SessionProjector } from "./session/projector"
import { SessionMessageTable, SessionTable } from "./session/sql"
import { SessionSchema } from "./session/schema"
import { AbsolutePath, PositiveInt, RelativePath } from "./schema"
import { AgentV2 } from "./agent"
import { SessionV1 } from "./v1/session"
import { InstallationVersion } from "./installation/version"
import { Slug } from "./util/slug"
import { ProjectTable } from "./project/sql"
import path from "path"
import { fromRow } from "./session/info"
import { SessionRunner } from "./session/runner/index"
import { SessionStore } from "./session/store"
import { SessionExecution } from "./session/execution"
import { makeGlobalNode } from "./effect/app-node"
import { LocationServiceMap } from "./location-service-map"
import { MessageDecodeError } from "./session/error"
import { SessionEvent } from "./session/event"
import { SessionInput } from "./session/input"
import { Snapshot } from "./snapshot"
import { SessionCompaction } from "./session/compaction"
import { SessionRevert } from "./session/revert"
import { Revert } from "@opencode-ai/schema/revert"
import { FSUtil } from "./fs-util"
import type { EventLog } from "@opencode-ai/schema/event-log"
import { SkillV2 } from "./skill"
import { Job } from "./job"
import { CommandV2 } from "./command"
import { Shell } from "./shell"
import { Shell as ShellSchema } from "@opencode-ai/schema/shell"
import { KeyedMutex } from "./effect/keyed-mutex"

export const RevertState = Revert.State
export type RevertState = Revert.State

// get project -> project.locations
//
// get all sessions
//

// - by project
//   - by subpath
// - by workspace (home is special)

export { ListAnchor }

const ListInputBase = {
  workspaceID: WorkspaceV2.ID.pipe(Schema.optional),
  search: Schema.String.pipe(Schema.optional),
  limit: PositiveInt.pipe(Schema.optional),
  order: Schema.Literals(["asc", "desc"]).pipe(Schema.optional),
  parentID: Schema.NullOr(SessionSchema.ID).pipe(Schema.optional),
  anchor: ListAnchor.pipe(Schema.optional),
}

const ListDirectoryInput = Schema.Struct({
  ...ListInputBase,
  directory: AbsolutePath,
})

const ListProjectInput = Schema.Struct({
  ...ListInputBase,
  project: ProjectV2.ID,
  subpath: RelativePath.pipe(Schema.optional),
})

const ListAllInput = Schema.Struct(ListInputBase)

export const ListInput = Schema.Union([ListDirectoryInput, ListProjectInput, ListAllInput])
export type ListInput = typeof ListInput.Type

type CreateBaseInput = {
  id?: SessionSchema.ID
  title?: string
  agent?: AgentV2.ID
  model?: ModelV2.Ref
}
type CreateInput = CreateBaseInput &
  ({ location: Location.Ref; parentID?: never } | { parentID: SessionSchema.ID; location?: never })

type CompactInput = {
  sessionID: SessionSchema.ID
}

type ForkInput = {
  sessionID: SessionSchema.ID
  messageID?: SessionMessage.ID
}

export class NotFoundError extends Schema.TaggedErrorClass<NotFoundError>()("Session.NotFoundError", {
  sessionID: SessionSchema.ID,
}) {}

export class OperationUnavailableError extends Schema.TaggedErrorClass<OperationUnavailableError>()(
  "Session.OperationUnavailableError",
  {
    operation: Schema.Literals(["move", "skill", "switchAgent", "compact"]),
  },
) {}

export { MessageDecodeError } from "./session/error"

export class PromptConflictError extends Schema.TaggedErrorClass<PromptConflictError>()("Session.PromptConflictError", {
  sessionID: SessionSchema.ID,
  messageID: SessionMessage.ID,
}) {}
export class BusyError extends Schema.TaggedErrorClass<BusyError>()("Session.BusyError", {
  sessionID: SessionSchema.ID,
}) {}
export class SkillNotFoundError extends Schema.TaggedErrorClass<SkillNotFoundError>()("Session.SkillNotFoundError", {
  skill: Schema.String,
}) {}
export const MessageNotFoundError = SessionRevert.MessageNotFoundError
export type MessageNotFoundError = SessionRevert.MessageNotFoundError

export type Error =
  | NotFoundError
  | MessageDecodeError
  | OperationUnavailableError
  | PromptConflictError
  | BusyError
  | SkillNotFoundError
  | CommandV2.NotFoundError
  | CommandV2.EvaluationError
  | MessageNotFoundError

export interface Interface {
  readonly list: (input?: ListInput) => Effect.Effect<{
    readonly data: SessionSchema.Info[]
    /** Per-session durable log watermark, read in the same transaction as the snapshot. Sessions without events are absent. */
    readonly watermarks: ReadonlyMap<string, EventV2.Seq>
  }>
  readonly create: (input: CreateInput) => Effect.Effect<SessionSchema.Info, NotFoundError>
  readonly fork: (input: ForkInput) => Effect.Effect<SessionSchema.Info, NotFoundError | MessageNotFoundError>
  readonly get: (sessionID: SessionSchema.ID) => Effect.Effect<SessionSchema.Info, NotFoundError>
  readonly messages: (input: {
    sessionID: SessionSchema.ID
    limit?: number
    order?: "asc" | "desc"
    cursor?: {
      id: SessionMessage.ID
      direction: "previous" | "next"
    }
  }) => Effect.Effect<SessionMessage.Message[], NotFoundError | MessageDecodeError>
  readonly message: (input: {
    sessionID: SessionSchema.ID
    messageID: SessionMessage.ID
  }) => Effect.Effect<SessionMessage.Message | undefined>
  readonly context: (
    sessionID: SessionSchema.ID,
  ) => Effect.Effect<SessionMessage.Message[], NotFoundError | MessageDecodeError>
  /**
   * Durable, ordered, gap-free session log read. Replays public durable
   * session events after the exclusive `after` cursor, emits a `Synced`
   * marker at the captured replay watermark, then continues live when `follow`
   * is set.
   * The marker's seq may exceed the last emitted event because non-public
   * durable events share the aggregate's sequence space.
   */
  readonly log: (input: {
    sessionID: SessionSchema.ID
    after?: number
    follow?: boolean
  }) => Stream.Stream<SessionEvent.DurableEvent | EventLog.Synced, NotFoundError>
  /** Latest durable log seq per session. Sessions without events are absent. */
  readonly watermarks: (sessionIDs: ReadonlyArray<SessionSchema.ID>) => Effect.Effect<ReadonlyMap<string, EventV2.Seq>>
  readonly switchAgent: (input: { sessionID: SessionSchema.ID; agent: string }) => Effect.Effect<void, NotFoundError>
  readonly switchModel: (input: {
    sessionID: SessionSchema.ID
    model: ModelV2.Ref
  }) => Effect.Effect<void, NotFoundError>
  readonly rename: (input: { sessionID: SessionSchema.ID; title: string }) => Effect.Effect<void, NotFoundError>
  readonly prompt: (input: {
    id?: SessionMessage.ID
    sessionID: SessionSchema.ID
    prompt: PromptInput.Prompt
    delivery?: SessionInput.Delivery
    resume?: boolean
  }) => Effect.Effect<SessionInput.Admitted, NotFoundError | PromptConflictError>
  readonly command: (input: {
    id?: SessionMessage.ID
    sessionID: SessionSchema.ID
    command: string
    arguments?: string
    agent?: string
    model?: ModelV2.Ref
    files?: PromptInput.Prompt["files"]
    agents?: PromptInput.Prompt["agents"]
    delivery?: SessionInput.Delivery
    resume?: boolean
  }) => Effect.Effect<
    SessionInput.Admitted,
    NotFoundError | PromptConflictError | CommandV2.NotFoundError | CommandV2.EvaluationError
  >
  readonly shell: (input: {
    id?: EventV2.ID
    sessionID: SessionSchema.ID
    command: string
  }) => Effect.Effect<void, NotFoundError>
  readonly skill: (input: {
    id?: SessionMessage.ID
    sessionID: SessionSchema.ID
    skill: string
    resume?: boolean
  }) => Effect.Effect<void, NotFoundError | SkillNotFoundError>
  readonly compact: (
    input: CompactInput,
  ) => Effect.Effect<void, NotFoundError | BusyError | MessageDecodeError | OperationUnavailableError>
  readonly wait: (id: SessionSchema.ID) => Effect.Effect<void, NotFoundError>
  readonly active: Effect.Effect<ReadonlySet<SessionSchema.ID>>
  readonly background: (sessionID: SessionSchema.ID) => Effect.Effect<void, NotFoundError>
  readonly resume: (sessionID: SessionSchema.ID) => Effect.Effect<void, NotFoundError | SessionRunner.RunError>
  readonly interrupt: (sessionID: SessionSchema.ID) => Effect.Effect<void>
  readonly synthetic: (input: {
    sessionID: SessionSchema.ID
    text: string
    description?: string
    metadata?: Record<string, unknown>
  }) => Effect.Effect<void, NotFoundError>
  readonly revert: {
    readonly stage: (input: {
      sessionID: SessionSchema.ID
      messageID: SessionMessage.ID
      files?: boolean
    }) => Effect.Effect<Revert.State, NotFoundError | MessageNotFoundError | BusyError | Snapshot.Error>
    readonly clear: (sessionID: SessionSchema.ID) => Effect.Effect<void, NotFoundError | BusyError | Snapshot.Error>
    readonly commit: (sessionID: SessionSchema.ID) => Effect.Effect<void, NotFoundError | BusyError>
  }
}

export class Service extends Context.Service<Service, Interface>()("@opencode/v2/Session") {}

const layer = Layer.effect(
  Service,
  Effect.gen(function* () {
    const database = yield* Database.Service
    const db = database.db
    const events = yield* EventV2.Service
    const projects = yield* ProjectV2.Service
    const execution = yield* SessionExecution.Service
    const store = yield* SessionStore.Service
    const locations = yield* LocationServiceMap.Service
    const jobs = yield* Job.Service
    const scope = yield* Scope.Scope
    const activeShells = new Set<SessionSchema.ID>()
    const shellLocks = KeyedMutex.makeUnsafe<SessionSchema.ID>()
    const decodeMessage = Schema.decodeUnknownEffect(SessionMessage.Message)
    const isDurableSessionEvent = Schema.is(SessionEvent.Durable)
    const decode = (row: typeof SessionMessageTable.$inferSelect) =>
      decodeMessage({ ...row.data, id: row.id, type: row.type }).pipe(
        Effect.mapError(
          () =>
            new MessageDecodeError({
              sessionID: SessionSchema.ID.make(row.session_id),
              messageID: SessionMessage.ID.make(row.id),
            }),
        ),
      )

    const result = Service.of({
      create: Effect.fn("V2Session.create")(function* (input) {
        const sessionID = input.id ?? SessionSchema.ID.create()
        const recorded = yield* store.get(sessionID)
        if (recorded) return recorded
        const parent = input.parentID ? yield* store.get(input.parentID) : undefined
        if (input.parentID && parent === undefined) return yield* new NotFoundError({ sessionID: input.parentID })
        const location = parent?.location ?? input.location
        if (location === undefined)
          return yield* Effect.die(new Error("V2Session.create requires either location or an existing parentID"))
        const project = yield* projects.resolve(location.directory)
        yield* db
          .insert(ProjectTable)
          .values({ id: project.id, worktree: project.directory, vcs: project.vcs?.type, sandboxes: [] })
          .onConflictDoNothing()
          .run()
          .pipe(Effect.orDie)
        const now = Date.now()
        const info = SessionV1.SessionInfo.make({
          id: sessionID,
          slug: Slug.create(),
          version: InstallationVersion,
          projectID: project.id,
          parentID: input.parentID,
          directory: location.directory,
          path: path.relative(project.directory, location.directory).replaceAll("\\", "/"),
          workspaceID: location.workspaceID ? WorkspaceV2.ID.make(location.workspaceID) : undefined,
          title: input.title ?? `New session - ${new Date(now).toISOString()}`,
          agent: input.agent,
          model: input.model
            ? {
                id: ModelV2.ID.make(input.model.id),
                providerID: input.model.providerID,
                variant: input.model.variant,
              }
            : undefined,
          cost: 0,
          tokens: { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } },
          time: { created: now, updated: now },
        })
        const projected = yield* events.publish(SessionV1.Event.Created, { sessionID, info }, { location }).pipe(
          Effect.as({ type: "created" } as const),
          Effect.catchDefect((defect) => {
            if (!(defect instanceof SessionProjector.SessionAlreadyProjected)) {
              return Effect.die(defect)
            }
            // Concurrent creation lost the projection race. The existing Session identity wins.
            return store
              .get(sessionID)
              .pipe(
                Effect.flatMap((session) =>
                  session ? Effect.succeed({ type: "existing", session } as const) : Effect.die(defect),
                ),
              )
          }),
        )
        if (projected.type === "existing") return projected.session
        // TODO: Restore recorded sessions onto replacement synchronized workspaces in a future API slice.
        return yield* result.get(sessionID).pipe(Effect.orDie)
      }),
      fork: Effect.fn("V2Session.fork")(function* (input) {
        const parent = yield* result.get(input.sessionID)
        const boundary = input.messageID
          ? yield* db
              .select({ seq: SessionMessageTable.seq })
              .from(SessionMessageTable)
              .where(
                and(eq(SessionMessageTable.session_id, input.sessionID), eq(SessionMessageTable.id, input.messageID)),
              )
              .get()
              .pipe(Effect.orDie)
          : undefined
        if (input.messageID && !boundary)
          return yield* new MessageNotFoundError({ sessionID: input.sessionID, messageID: input.messageID })
        const sessionID = SessionSchema.ID.create()
        yield* events.publish(SessionEvent.Forked, {
          sessionID,
          parentID: parent.id,
          from: input.messageID,
        })
        return yield* result.get(sessionID).pipe(Effect.orDie)
      }),
      get: Effect.fn("V2Session.get")(function* (sessionID) {
        const session = yield* store.get(sessionID)
        if (!session) return yield* new NotFoundError({ sessionID })
        return session
      }),
      list: Effect.fn("V2Session.list")(function* (input = {}) {
        const direction = input.anchor?.direction ?? "next"
        const requestedOrder = input.order ?? "desc"
        const order = direction === "previous" ? (requestedOrder === "asc" ? "desc" : "asc") : requestedOrder
        const sortColumn = SessionTable.time_updated
        const conditions: SQL[] = []
        if ("directory" in input) conditions.push(eq(SessionTable.directory, input.directory))
        if (input.workspaceID) conditions.push(eq(SessionTable.workspace_id, input.workspaceID))
        if ("project" in input) conditions.push(eq(SessionTable.project_id, input.project))
        if (input.search) conditions.push(like(SessionTable.title, `%${input.search}%`))
        if (input.parentID !== undefined)
          conditions.push(
            input.parentID === null ? isNull(SessionTable.parent_id) : eq(SessionTable.parent_id, input.parentID),
          )
        if (input.anchor) {
          conditions.push(
            order === "asc"
              ? or(
                  gt(sortColumn, input.anchor.time),
                  and(eq(sortColumn, input.anchor.time), gt(SessionTable.id, input.anchor.id)),
                )!
              : or(
                  lt(sortColumn, input.anchor.time),
                  and(eq(sortColumn, input.anchor.time), lt(SessionTable.id, input.anchor.id)),
                )!,
          )
        }
        const query = db
          .select()
          .from(SessionTable)
          .where(conditions.length > 0 ? and(...conditions) : undefined)
          .orderBy(
            order === "asc" ? asc(sortColumn) : desc(sortColumn),
            order === "asc" ? asc(SessionTable.id) : desc(SessionTable.id),
          )
        // Watermarks must pair with the snapshot exactly, so both reads share a transaction:
        // a higher watermark would let an attached tail skip events missing from the snapshot.
        const snapshot = yield* db
          .transaction(() =>
            Effect.gen(function* () {
              const rows = yield* (input.limit === undefined ? query.all() : query.limit(input.limit).all()).pipe(
                Effect.orDie,
              )
              const watermarks = yield* events.sequences(rows.map((row) => row.id))
              return { rows, watermarks }
            }),
          )
          .pipe(Effect.orDie)
        const rows = direction === "previous" ? snapshot.rows.toReversed() : snapshot.rows
        return { data: rows.map((row) => fromRow(row)), watermarks: snapshot.watermarks }
      }),
      messages: Effect.fn("V2Session.messages")(function* (input) {
        yield* result.get(input.sessionID)
        const direction = input.cursor?.direction ?? "next"
        const requestedOrder = input.order ?? "desc"
        const order = direction === "previous" ? (requestedOrder === "asc" ? "desc" : "asc") : requestedOrder
        const anchor = input.cursor
          ? yield* db
              .select({ seq: SessionMessageTable.seq })
              .from(SessionMessageTable)
              .where(
                and(eq(SessionMessageTable.session_id, input.sessionID), eq(SessionMessageTable.id, input.cursor.id)),
              )
              .get()
              .pipe(Effect.orDie)
          : undefined
        if (input.cursor && !anchor) return []
        const boundary = anchor
          ? order === "asc"
            ? gt(SessionMessageTable.seq, anchor.seq)
            : lt(SessionMessageTable.seq, anchor.seq)
          : undefined
        const where = boundary
          ? and(eq(SessionMessageTable.session_id, input.sessionID), boundary)
          : eq(SessionMessageTable.session_id, input.sessionID)
        const query = db
          .select()
          .from(SessionMessageTable)
          .where(where)
          .orderBy(order === "asc" ? asc(SessionMessageTable.seq) : desc(SessionMessageTable.seq))
        const rows = yield* (input.limit === undefined ? query.all() : query.limit(input.limit).all()).pipe(
          Effect.orDie,
        )
        return yield* Effect.forEach(direction === "previous" ? rows.toReversed() : rows, decode)
      }),
      message: Effect.fn("V2Session.message")(function* (input) {
        const stored = yield* store.message(input.messageID)
        return stored?.sessionID === input.sessionID ? stored.message : undefined
      }),
      context: Effect.fn("V2Session.context")(function* (sessionID) {
        yield* result.get(sessionID)
        return yield* store.context(sessionID)
      }),
      log: (input) =>
        Stream.unwrap(
          result
            .get(input.sessionID)
            .pipe(Effect.as(events.log({ aggregateID: input.sessionID, after: input.after, follow: input.follow }))),
        ).pipe(
          Stream.filter(
            (item): item is SessionEvent.DurableEvent | EventLog.Synced =>
              EventV2.isSynced(item) || isDurableSessionEvent(item),
          ),
        ),
      watermarks: Effect.fn("V2Session.watermarks")(function* (sessionIDs) {
        return yield* events.sequences(sessionIDs)
      }),
      prompt: Effect.fn("V2Session.prompt")((input) =>
        Effect.uninterruptible(
          Effect.gen(function* () {
            const session = yield* result.get(input.sessionID)
            // A staged revert must be committed before admitting new input so the prompt
            // continues from the reverted boundary rather than stale post-boundary history.
            if (session.revert)
              yield* SessionRevert.commit(session).pipe(Effect.provideService(EventV2.Service, events))
            const prompt = resolvePrompt(input.prompt)
            const messageID = input.id ?? SessionMessage.ID.create()
            const delivery = input.delivery ?? "steer"
            const expected = { sessionID: input.sessionID, messageID, prompt, delivery }
            const admitted = yield* SessionInput.admit(db, events, {
              id: messageID,
              sessionID: input.sessionID,
              prompt,
              delivery,
            }).pipe(
              Effect.catchDefect((defect) =>
                defect instanceof SessionInput.LifecycleConflict
                  ? new PromptConflictError({ sessionID: input.sessionID, messageID })
                  : Effect.die(defect),
              ),
            )
            if (!SessionInput.equivalent(admitted, expected))
              return yield* new PromptConflictError({ sessionID: input.sessionID, messageID })
            if (input.resume !== false) {
              if (activeShells.has(admitted.sessionID)) return admitted
              yield* execution.wake(admitted.sessionID)
            }
            return admitted
          }),
        ),
      ),
      command: Effect.fn("V2Session.command")(function* (input) {
        const session = yield* result.get(input.sessionID)
        const commands = yield* CommandV2.Service.pipe(Effect.provide(locations.get(session.location)))
        const command = yield* commands.get(input.command)
        if (!command)
          return yield* new CommandV2.NotFoundError({
            command: input.command,
            message: `Command not found: ${input.command}`,
          })
        const evaluated = yield* commands.evaluate({ name: input.command, arguments: input.arguments })

        // TODO(v2 commands): decide whether command-level subtask/background execution belongs in v2 commands.
        const agent = command.agent ?? input.agent
        const commandAgent = yield* Effect.gen(function* () {
          if (!command.agent) return undefined
          const agents = yield* AgentV2.Service.pipe(Effect.provide(locations.get(session.location)))
          return yield* agents.get(AgentV2.ID.make(command.agent))
        })
        const model = command.model ?? commandAgent?.model ?? input.model
        if (agent !== undefined && session.agent !== AgentV2.ID.make(agent))
          yield* result.switchAgent({ sessionID: input.sessionID, agent })
        if (model !== undefined) yield* result.switchModel({ sessionID: input.sessionID, model })

        return yield* result.prompt({
          id: input.id,
          sessionID: input.sessionID,
          prompt: { text: evaluated.text, files: input.files, agents: input.agents },
          delivery: input.delivery,
          resume: input.resume,
        })
      }),
      shell: Effect.fn("V2Session.shell")(function* (input) {
        const session = yield* result.get(input.sessionID)
        yield* shellLocks.withLock(input.sessionID)(
          Effect.gen(function* () {
            activeShells.add(input.sessionID)
            if ((yield* execution.active).has(input.sessionID)) yield* execution.awaitIdle(input.sessionID)
            const started = yield* Effect.gen(function* () {
              const shell = yield* Shell.Service
              return yield* shell.create({ command: input.command, cwd: session.location.directory })
            })
              .pipe(Effect.provide(locations.get(session.location)))
            yield* events.publish(
              SessionEvent.Shell.Started,
              {
                sessionID: input.sessionID,
                shell: started,
              },
              { id: input.id },
            )
            const completed = yield* Effect.gen(function* () {
              const shell = yield* Shell.Service
              const terminal = yield* shell.wait(started.id).pipe(
                Effect.map((info) => ({ info, retained: true as const })),
                Effect.catchTag("Shell.NotFoundError", () =>
                  Effect.succeed({ info: synthesizeTerminalShellInfo(started), retained: false as const }),
                ),
              )
              const output = terminal.retained
                ? yield* shell
                    .output(started.id, { limit: SHELL_MAX_CAPTURE_BYTES })
                    .pipe(Effect.catchTag("Shell.NotFoundError", () => Effect.succeed(missingShellOutput())))
                : missingShellOutput()
              return { shell: terminal.info, output }
            }).pipe(Effect.provide(locations.get(session.location)))
            yield* events.publish(SessionEvent.Shell.Ended, {
              sessionID: input.sessionID,
              shell: completed.shell,
              output: completed.output,
            })
          }).pipe(
            Effect.ensuring(
              Effect.gen(function* () {
                activeShells.delete(input.sessionID)
                yield* execution.wake(input.sessionID)
              }),
            ),
          ),
        )
      }),
      skill: Effect.fn("V2Session.skill")(function* (input) {
        const session = yield* result.get(input.sessionID)
        const skills = yield* SkillV2.Service.pipe(Effect.provide(locations.get(session.location)))
        const skill = (yield* skills.list()).find((item) => item.name === input.skill)
        if (!skill) return yield* new SkillNotFoundError({ skill: input.skill })
        yield* events.publish(SessionEvent.Skill.Activated, {
          sessionID: input.sessionID,
          name: skill.name,
          text: skill.content,
        })
        if (input.resume !== false)
          yield* execution
            .resume(input.sessionID)
            .pipe(Effect.ignore, Effect.forkIn(scope, { startImmediately: true }), Effect.asVoid)
      }),
      switchAgent: Effect.fn("V2Session.switchAgent")(function* (input) {
        yield* result.get(input.sessionID)
        yield* events.publish(SessionEvent.AgentSelected, {
          sessionID: input.sessionID,
          agent: input.agent,
        })
      }),
      switchModel: Effect.fn("V2Session.switchModel")(function* (input) {
        const session = yield* result.get(input.sessionID)
        if (
          session.model?.providerID === input.model.providerID &&
          session.model.id === input.model.id &&
          (session.model.variant ?? "default") === (input.model.variant ?? "default")
        )
          return
        yield* events.publish(SessionEvent.ModelSelected, {
          sessionID: input.sessionID,
          model: input.model,
        })
      }),
      rename: Effect.fn("V2Session.rename")(function* (input) {
        yield* result.get(input.sessionID)
        yield* events.publish(SessionEvent.Renamed, {
          sessionID: input.sessionID,
          title: input.title,
        })
      }),
      compact: Effect.fn("V2Session.compact")(function* (input) {
        const session = yield* result.get(input.sessionID)
        // TODO: admit manual compaction as durable pending work, like prompt input, instead of rejecting active sessions.
        if ((yield* execution.active).has(input.sessionID)) return yield* new BusyError({ sessionID: input.sessionID })
        const context = yield* store.context(input.sessionID)
        const compacted = yield* Effect.gen(function* () {
          const compaction = yield* SessionCompaction.Service
          return yield* compaction.compactManual({ session, messages: context })
        }).pipe(
          Effect.provide(locations.get(session.location)),
          Effect.catch(() => Effect.succeed(false)),
        )
        if (!compacted) return yield* new OperationUnavailableError({ operation: "compact" })
        return undefined
      }),
      wait: Effect.fn("V2Session.wait")(function* (sessionID) {
        yield* result.get(sessionID)
        yield* execution.awaitIdle(sessionID)
      }),
      active: execution.active,
      background: Effect.fn("V2Session.background")(function* (sessionID) {
        yield* result.get(sessionID)
        const backgrounded = yield* jobs.backgroundAll({ sessionID })
        if (backgrounded.length === 0) return
        yield* result.synthetic({
          sessionID,
          text: [
            "User requested that active blocking work be moved to the background.",
            "",
            "Backgrounded work:",
            ...backgrounded.map((job) => `- ${job.type}: ${job.title && job.title.length > 0 ? job.title : job.id}`),
            "",
            "The backgrounded work is still unfinished. Move on to other work if you can. If there is nothing else useful to do, finish your response. Do not wait, sleep, poll, or report the backgrounded work as complete until a later completion notification is added to the conversation.",
          ].join("\n"),
        })
      }),
      resume: Effect.fn("V2Session.resume")(function* (sessionID) {
        yield* result.get(sessionID)
        yield* execution.resume(sessionID)
      }),
      synthetic: Effect.fn("V2Session.synthetic")(function* (input) {
        yield* result.get(input.sessionID)
        yield* events.publish(SessionEvent.Synthetic, {
          sessionID: input.sessionID,
          text: input.text,
          description: input.description,
          metadata: input.metadata,
        })
        yield* execution
          .resume(input.sessionID)
          .pipe(Effect.ignore, Effect.forkIn(scope, { startImmediately: true }), Effect.asVoid)
      }),
      interrupt: Effect.fn("V2Session.interrupt")((sessionID) =>
        Effect.uninterruptible(execution.interrupt(sessionID)),
      ),
      revert: {
        stage: Effect.fn("V2Session.revert.stage")(function* (input) {
          const session = yield* result.get(input.sessionID)
          if ((yield* execution.active).has(input.sessionID))
            return yield* new BusyError({ sessionID: input.sessionID })
          return yield* SessionRevert.stage({ session, messageID: input.messageID, files: input.files }).pipe(
            Effect.provideService(Database.Service, database),
            Effect.provideService(EventV2.Service, events),
            Effect.provide(locations.get(session.location)),
          )
        }),
        clear: Effect.fn("V2Session.revert.clear")(function* (sessionID) {
          const session = yield* result.get(sessionID)
          if ((yield* execution.active).has(sessionID)) return yield* new BusyError({ sessionID })
          return yield* SessionRevert.clear(session).pipe(
            Effect.provideService(EventV2.Service, events),
            Effect.provide(locations.get(session.location)),
          )
        }),
        commit: Effect.fn("V2Session.revert.commit")(function* (sessionID) {
          const session = yield* result.get(sessionID)
          if ((yield* execution.active).has(sessionID)) return yield* new BusyError({ sessionID })
          return yield* SessionRevert.commit(session).pipe(Effect.provideService(EventV2.Service, events))
        }),
      },
    })

    return result
  }),
)

function missingShellOutput() {
  const output = "Shell command output is no longer available."
  return {
    output,
    cursor: Buffer.byteLength(output),
    size: Buffer.byteLength(output),
    truncated: false,
  }
}

function synthesizeTerminalShellInfo(started: ShellSchema.Info): ShellSchema.Info {
  return {
    ...started,
    // The Shell record was removed before waiters could observe it; publish a terminal
    // boundary instead of leaving the Session shell message permanently running.
    status: "killed",
    time: { ...started.time, completed: Date.now() },
  }
}

const resolvePrompt = (input: PromptInput.Prompt) =>
  Prompt.make({
    text: input.text,
    agents: input.agents,
    files: input.files?.map((file) => {
      const dataMime = file.uri.match(/^data:([^;,]+)[;,]/i)?.[1]
      const target = URL.canParse(file.uri) ? new URL(file.uri).pathname : (file.name ?? file.uri)
      return {
        ...file,
        mime: dataMime ?? (target.endsWith("/") ? "application/x-directory" : FSUtil.mimeType(target)),
      }
    }),
  })

// Mirrors the shell tool's in-memory preview safety limit.
const SHELL_MAX_CAPTURE_BYTES = 1024 * 1024

export const node = makeGlobalNode({
  service: Service,
  layer: layer.pipe(Layer.orDie),
  deps: [
    Job.node,
    Database.node,
    EventV2.node,
    ProjectV2.node,
    SessionExecution.node,
    SessionStore.node,
    LocationServiceMap.node,
    SessionProjector.node,
  ],
})