feat(hooks): add team-mode status injector hook with tests

src/hooks/team-mode-status-injector/hook.ts

@@ -0,0 +1,126 @@
+import type { TeamModeConfig } from "../../config/schema/team-mode"
+
+type TransformPart = {
+  type: string
+  text?: string
+  synthetic?: boolean
+  [key: string]: unknown
+}
+
+type TransformMessageInfo = {
+  role: string
+  sessionID?: string
+  [key: string]: unknown
+}
+
+type MessageWithParts = {
+  info: TransformMessageInfo
+  parts: TransformPart[]
+}
+
+type TeamModeStatusInjectorInput = {
+  sessionID?: string
+  [key: string]: unknown
+}
+
+type TeamModeStatusInjectorOutput = {
+  messages: MessageWithParts[]
+}
+
+export type TeamModeStatusInjectorHook = {
+  "experimental.chat.messages.transform"?: (
+    input: TeamModeStatusInjectorInput,
+    output: TeamModeStatusInjectorOutput,
+  ) => Promise<void>
+}
+
+const TEAM_MODE_STATUS_MARKER = "<team_mode_status enabled=\"true\">"
+
+function resolveSessionID(
+  input: TeamModeStatusInjectorInput,
+  messages: MessageWithParts[],
+): string | undefined {
+  if (typeof input.sessionID === "string" && input.sessionID.length > 0) {
+    return input.sessionID
+  }
+
+  for (let index = messages.length - 1; index >= 0; index -= 1) {
+    const sessionID = messages[index]?.info.sessionID
+    if (typeof sessionID === "string" && sessionID.length > 0) {
+      return sessionID
+    }
+  }
+
+  return undefined
+}
+
+function findLastUserMessageIndex(messages: MessageWithParts[]): number {
+  for (let index = messages.length - 1; index >= 0; index -= 1) {
+    if (messages[index]?.info.role === "user") {
+      return index
+    }
+  }
+
+  return -1
+}
+
+function hasInjectedTeamModeStatus(messages: MessageWithParts[]): boolean {
+  return messages.some((message) =>
+    message.parts.some(
+      (part) => part.synthetic === true && part.type === "text" && part.text?.includes(TEAM_MODE_STATUS_MARKER),
+    ),
+  )
+}
+
+function buildTeamModeStatusContent(): string {
+  return `${TEAM_MODE_STATUS_MARKER}
+Team mode is ENABLED for this session.
+If the team_* tools are present, that is authoritative proof that team mode is active.
+Do not inspect ~/.config/opencode or project config files to verify team mode.
+If you need usage guidance, load the team-mode skill. Otherwise use the team_* tools directly.
+</team_mode_status>`
+}
+
+function createInjectedMessage(sessionID: string): MessageWithParts {
+  return {
+    info: {
+      role: "user",
+      sessionID,
+    },
+    parts: [{ type: "text", text: buildTeamModeStatusContent(), synthetic: true }],
+  }
+}
+
+export function createTeamModeStatusInjector(
+  config: TeamModeConfig,
+): TeamModeStatusInjectorHook {
+  return {
+    "experimental.chat.messages.transform": async (
+      input,
+      output,
+    ): Promise<void> => {
+      if (!config.enabled || output.messages.length === 0) {
+        return
+      }
+
+      if (hasInjectedTeamModeStatus(output.messages)) {
+        return
+      }
+
+      const sessionID = resolveSessionID(input, output.messages)
+      if (sessionID === undefined) {
+        return
+      }
+
+      const lastUserMessageIndex = findLastUserMessageIndex(output.messages)
+      const injectedMessage = createInjectedMessage(sessionID)
+
+      if (lastUserMessageIndex === -1) {
+        output.messages.unshift(injectedMessage)
+        return
+      }
+
+      output.messages.splice(lastUserMessageIndex, 0, injectedMessage)
+    },
+  }
+}