feat(cron): support DM and gateway platform targets for scheduled messages

[chaodu-agent]

Description

Allow cronjob scheduled messages to target DMs (direct messages) in addition to channels/threads, and support gateway-connected platforms (Telegram, LINE, Feishu, Google Chat, etc.) as delivery targets — not just Discord and Slack.

Use Case

As an operator, I want to receive scheduled prompts (daily summaries, reminders) as a DM rather than in a shared channel. Currently channel is required and only Discord/Slack channel IDs are supported. There is no way to send a cron message to:

1. A Discord DM with a specific user
2. A Telegram chat, LINE conversation, or Feishu DM via the custom gateway

This forces users to create private channels as a workaround for personal scheduled messages, and completely blocks cron usage for gateway-connected platforms.

Proposed Solution

Introduce a target_type field to distinguish delivery targets. The existing channel field is repurposed as target_id (with channel kept as an alias for backward compatibility).

Field Definition

Field	Required	Default	Description
target_type		"channel"	"channel" — post to a channel (current behavior). "thread" — post to an existing thread. "dm" — open/reuse a DM with a user.
target_id	✅	—	The ID of the target. Interpretation depends on target_type and platform.
channel		—	Alias for target_id (backward compat). If both are set, target_id takes precedence.
thread_id		—	When target_type = "channel", optionally post into this thread (existing behavior).

Examples

1. Channel (current behavior, unchanged)

Post to a Discord channel — creates a new thread for the agent reply:

[[cron.jobs]]
schedule = "0 9 * * 1-5"
platform = "discord"
target_type = "channel"              # default, can be omitted
target_id = "1490282656913559673"    # Discord channel ID
message = "summarize yesterday merged PRs"
sender_name = "DailyOps"
timezone = "Asia/Taipei"

2. Existing thread

Post into a specific existing thread:

[[cron.jobs]]
schedule = "0 9 * * 1-5"
platform = "discord"
target_type = "thread"
target_id = "1506450748169523282"    # Discord thread ID
message = "daily standup reminder"
sender_name = "StandupBot"
timezone = "Asia/Taipei"

3. Discord DM

Send a DM to a specific Discord user:

[[cron.jobs]]
schedule = "0 8 * * 1-5"
platform = "discord"
target_type = "dm"
target_id = "845835116920307722"     # Discord user ID
message = "good morning! here is your daily agenda"
sender_name = "MorningBot"
timezone = "Asia/Taipei"

OAB calls the Discord API to open (or reuse) a DM channel with the user, then sends the message there.

4. Gateway — Telegram DM

Send via the custom gateway to a Telegram user:

[[cron.jobs]]
schedule = "0 9 * * 1-5"
platform = "gateway"
target_type = "dm"
target_id = "123456789"              # Telegram user/chat ID
message = "daily security scan report"
sender_name = "SecurityBot"
timezone = "UTC"

5. Gateway — LINE DM

Send via the custom gateway to a LINE user:

[[cron.jobs]]
schedule = "0 18 * * 1-5"
platform = "gateway"
target_type = "dm"
target_id = "U1234567890abcdef"      # LINE user ID
message = "end of day summary"
sender_name = "EODBot"
timezone = "Asia/Taipei"

6. Gateway — Feishu group chat

Send to a Feishu group chat:

[[cron.jobs]]
schedule = "0 9 * * 1-5"
platform = "gateway"
target_type = "channel"
target_id = "oc_abcdef123456"        # Feishu chat_id
message = "weekly team sync reminder"
sender_name = "TeamBot"
timezone = "Asia/Shanghai"

7. Backward compatibility (existing config still works)

[[cron.jobs]]
schedule = "0 9 * * 1-5"
channel = "1490282656913559673"      # old field, treated as target_id with target_type="channel"
message = "summarize yesterday merged PRs"

Routing Logic

fire_cronjob()
  │
  ├─ platform = "discord" or "slack"
  │    ├─ target_type = "channel" → post to channel (create thread)  [existing behavior]
  │    ├─ target_type = "thread"  → post into existing thread
  │    └─ target_type = "dm"      → open DM channel with user, post there
  │
  └─ platform = "gateway"
       │  Emit GatewayEvent over WebSocket to custom gateway
       ├─ target_type = "channel" → gateway routes to group/channel
       ├─ target_type = "dm"      → gateway routes to 1:1 DM
       └─ target_type = "thread"  → gateway routes to thread/topic

The gateway uses target_id + platform credentials to call the appropriate API (Telegram sendMessage, LINE Push API, Feishu send_message, etc.).

Prior Art

• The gateway custom webhook already supports triggering agents from external cron jobs via curl -X POST (documented in gateway/README.md). This FR brings that capability into the native config-driven scheduler.
• Discord.js bots commonly support DM targets for scheduled messages via user.send().
• Discord API: POST /users/@me/channels with recipient_id to create/get a DM channel.

Related Issues

• feat(cron): change usercron relative path base from $HOME to $HOME/.openab #680 — usercron path migration (closed, related cron config)
• feat: usercron — hot-reload cronjob.toml for agent-managed schedules #628 — usercron hot-reload (closed, related cron feature)
• fix(cron): cronjob replies go to channel instead of creating a thread #612 — cronjob replies go to channel instead of thread (closed, related delivery target bug)
• feat(discord): add /remind slash command for one-shot delayed mentions #796 — /remind slash command (closed, related scheduled delivery to users)