Add Division-Specific Discord Roles, Announcement Channels, and Division Update API

[yulmwu]

Previously, the Discord role assigned during account linking and the channel used for challenge solve announcements were both hardcoded.

This PR introduces support for configuring both the assigned Discord role and the solve announcement channel on a per-Division basis.

These values can now be specified when creating a Division. If either value is omitted, no action is taken for that setting. To support modifying these values after creation, a new Division update API has also been added.

As part of this change, the previously hardcoded environment variables for the Discord role ID and announcement channel ID have been removed.

For more details, please refer to the updated API documentation and the changes included in this PR.

List Divisions

GET /api/divisions

Response 200

[
    {
        "id": 2,
        "name": "고등부",
        "discord_role_id": "1522163303982563458",
        "discord_announce_channel_id": "1522218332806447225",
        "created_at": "2026-01-26T12:00:00Z"
    }
]

Notes:

• Division identifiers are numeric id values (slugs are not supported).
• discord_role_id and discord_announce_channel_id are the per-division Discord
  role and announcement channel. They are omitted when unset and are managed by
  admins via Create / Update Division. See Admin and Discord.

---

Create Division (Admin)

POST /api/admin/divisions

Request

{
    "name": "고등부",
    "discord_role_id": "1522163303982563458",
    "discord_announce_channel_id": "1522218332806447225"
}

discord_role_id and discord_announce_channel_id are optional. discord_role_id
is the guild role granted to this division's members when they link Discord;
discord_announce_channel_id is the channel that receives this division's solve /
first-blood announcements. Both are omitted from the response when unset.

Response 201

{
    "id": 2,
    "name": "고등부",
    "discord_role_id": "1522163303982563458",
    "discord_announce_channel_id": "1522218332806447225",
    "created_at": "2026-01-26T12:00:00Z"
}

Errors:

• 400 invalid input
• 401 invalid token or missing access_token cookie
• 403 forbidden

Validation notes:

• name must be at most 10 characters (counted by Unicode code point).
• discord_role_id / discord_announce_channel_id, when present, must be numeric
  Discord IDs (snowflakes). An empty string clears the value.

---

Update Division (Admin)

PUT /api/admin/divisions/:id

Updates a division's name and per-division Discord configuration. Divisions cannot
be deleted.

Request

{
    "name": "고등부",
    "discord_role_id": "1522163303982563458",
    "discord_announce_channel_id": "1522218332806447225"
}

Omitting (or sending an empty string for) discord_role_id /
discord_announce_channel_id clears that setting.

Response 200

{
    "id": 2,
    "name": "고등부",
    "discord_role_id": "1522163303982563458",
    "discord_announce_channel_id": "1522218332806447225",
    "created_at": "2026-01-26T12:00:00Z"
}

Errors:

• 400 invalid input
• 401 invalid token or missing access_token cookie
• 403 forbidden
• 404 not found

Validation notes:

• Same as Create Division.

[codecov]

Codecov Report

❌ Patch coverage is 70.54264% with 38 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
internal/repo/division_repo.go	0.00%	14 Missing ⚠️
internal/service/discord_service.go	61.11%	9 Missing and 5 partials ⚠️
internal/service/division_service.go	89.47%	4 Missing ⚠️
internal/http/handlers/handler.go	78.57%	2 Missing and 1 partial ⚠️
internal/service/validation.go	90.00%	1 Missing and 1 partial ⚠️
internal/http/router.go	0.00%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!