feat: enhanced Discord thread management (auto-thread, LLM naming, configurable archive)

[howie]

Summary

受 OpenClaw Discord Workflow blog 文章啟發，為 OpenAB 新增進階 thread 管理功能，提升多人使用時的 Discord 體驗。

Current State vs Proposed

Feature	Current	Proposed
Thread creation	Only on @mention	Optional "direct mode" — auto-thread on any message
Thread naming	Truncate to 40 chars + GitHub URL shortening	Optional LLM-generated short titles
Auto-archive	Hardcoded OneDay	Configurable per-channel (60m, 1d, 3d, 1w)
Per-channel config	None	Independent settings per channel
Ignore other mentions	None	Skip when other bots are mentioned

Proposed Features

1. Configurable Auto-Archive Duration

• Current: Hardcoded AutoArchiveDuration::OneDay (discord.rs:366)
• Goal: Add auto_archive_duration to config.toml
• Support Discord API's four options: 60, 1440, 4320, 10080 minutes
• Global default with per-channel override
• Validate at config load time (not at Discord API call time)

2. LLM-Generated Thread Names

• Current: shorten_thread_name() truncates to 40 chars (discord.rs:338-348)
• Goal: Add thread_name_mode setting: "truncate" (current) or "generated"
• In "generated" mode, use a lightweight API call (not ACP session) to generate a short title (≤100 chars, Discord limit)
• Implementation: Standalone API call, not through ACP session pool (avoids lock contention since thread doesn't exist yet at naming time)
• Fallback to truncate mode on failure, 3s timeout
• Note: 40-char limit is a design choice, not a Discord constraint — consider relaxing

3. Direct Mode (Auto-Thread without Mention)

• Current: Must @mention bot in main channel to trigger
• Goal: Add require_mention setting (per-channel)
• false = "direct mode": any message auto-creates a thread
• Suitable for dedicated bot channels
• Considerations:
  • Race condition: concurrent messages may trigger parallel thread creation — add per-channel debounce or mutex
  • Bot loop prevention: in direct mode, other bots' messages would also trigger threads — should skip all bot messages

4. Ignore Other Mentions

• Goal: Add ignore_other_mentions setting
• When a message mentions other bots/users but not this bot, don't respond
• Prevents false triggers in multi-bot environments

5. Per-Channel Configuration

• Goal: Allow independent settings per channel, overriding global defaults

[discord]
bot_token = "${DISCORD_BOT_TOKEN}"
allowed_channels = ["111111", "222222"]
auto_archive_duration = 1440
thread_name_mode = "truncate"
require_mention = true
ignore_other_mentions = false

[discord.channels."111111"]
auto_archive_duration = 60
require_mention = false

[discord.channels."222222"]
thread_name_mode = "generated"
auto_archive_duration = 10080

Files to Modify

• src/config.rs — Channel-level config structs + validation
• src/discord.rs — Thread creation logic, mention handling
• config.toml.example — Updated example
• charts/openab/templates/configmap.yaml — Helm template for per-channel config
• charts/openab/values.yaml — New values
• README.md — Document Manage Threads permission requirement

Implementation Priority

1. Configurable auto-archive duration (smallest change)
2. Per-channel configuration (foundation for other features)
3. Direct mode / require_mention (validates per-channel config)
4. Ignore other mentions (builds on direct mode)
5. LLM-generated thread names (most complex, requires standalone API integration)

References

• Blog: https://hanamizuki.tw/openclaw-discord-workflow/
• Discord Auto-Archive API: 60, 1440, 4320, 10080 minutes
• Current thread creation: src/discord.rs:350-371
• Current thread naming: src/discord.rs:338-348

[CHC-Agent]

Issue at a Glance

Current Discord config (flat):
  [discord]
  allowed_channels = ["111", "222"]     ← same settings for all
  auto_archive = OneDay (hardcoded)     ← not configurable

Proposed (per-channel):
  [discord.channels."111"]
  require_mention = false               ← direct mode
  auto_archive_duration = 60            ← 1 hour

  [discord.channels."222"]
  thread_name_mode = "generated"        ← LLM naming
  auto_archive_duration = 10080         ← 1 week

Hi @howie,

Thorough proposal. All 5 features are feasible — verified against current source:

• auto_archive_duration is hardcoded OneDay at discord.rs:581, easy to make configurable
• DiscordConfig has a flat allowed_channels Vec, per-channel config needs a new ChannelConfig struct
• require_mention toggle is straightforward since the @mention check already exists

PR #215 is already up and covers all 5 features.

Note: #164 (mention-only mode by @masami-agent) is a subset of this issue's require_mention feature. If #188 lands, #164 can likely be closed.

One concern from PR #215: LLM thread naming uses the same ACP session and holds the global write lock during naming. Worth noting for high-concurrency deployments.