oh-my-opencode/src/hooks/think-mode/index.ts

import { detectThinkKeyword, extractPromptText } from "./detector"
import { getHighVariant, isAlreadyHighVariant } from "./switcher"
import type { ThinkModeState, ThinkModeInput } from "./types"

export * from "./detector"
export * from "./switcher"
export * from "./types"

const thinkModeState = new Map<string, ThinkModeState>()

export function clearThinkModeState(sessionID: string): void {
  thinkModeState.delete(sessionID)
}

export function createThinkModeHook() {
  return {
    "chat.params": async (
      output: ThinkModeInput,
      sessionID: string
    ): Promise<void> => {
      const promptText = extractPromptText(output.parts)

      const state: ThinkModeState = {
        requested: false,
        modelSwitched: false,
      }

      if (!detectThinkKeyword(promptText)) {
        thinkModeState.set(sessionID, state)
        return
      }

      state.requested = true

      const currentModel = output.message.model
      if (!currentModel) {
        thinkModeState.set(sessionID, state)
        return
      }

      state.providerID = currentModel.providerID
      state.modelID = currentModel.modelID

      if (isAlreadyHighVariant(currentModel.modelID)) {
        thinkModeState.set(sessionID, state)
        return
      }

      const highVariant = getHighVariant(currentModel.modelID)

      if (!highVariant) {
        thinkModeState.set(sessionID, state)
        return
      }

      output.message.model = {
        providerID: currentModel.providerID,
        modelID: highVariant,
      }
      state.modelSwitched = true
      thinkModeState.set(sessionID, state)
    },

    event: async ({ event }: { event: { type: string; properties?: unknown } }) => {
      if (event.type === "session.deleted") {
        const props = event.properties as { info?: { id?: string } } | undefined
        if (props?.info?.id) {
          thinkModeState.delete(props.info.id)
        }
      }
    },
  }
}