Slack

Slack delivery is personal direct messages from a workspace bot. Channels and incoming webhooks are not used — the per-rule routing model wants one DM per recipient, which webhooks can't do.

1. Create the Slack app

1. api.slack.com/apps → Create New App → From scratch → pick your workspace.
2. OAuth & Permissions → Scopes → Bot Token Scopes, add:
3. chat:write — required, lets the bot post messages
4. im:write — required, lets the bot open a DM channel with each user
5. users:read.email — optional, only if you want Preesta to map emails to Slack user IDs automatically (otherwise you paste IDs into slackUsers: yourself)
6. Install to Workspace → copy the Bot User OAuth Token (xoxb-…).

2. Configure

Add to appsettings.secrets.yaml (gitignored, sits next to appsettings.yaml in the Preesta install — alongside any Smtp: / Telegram: sections):

Slack:
  botToken: "xoxb-EXAMPLE-EXAMPLE-replaceme"

3. Use in rules

Two orthogonal mechanisms — combine as needed.

Per-rule explicit user IDs (always-on, one-for-all):

- tracker: jira
  filter: "DueDate < startOfDay() AND Resolution is EMPTY"
  notify:
    subject: "Due-date expired"
    mailTo: assignee
    slackUserId: "U01ABCDEFG,U02HIJKLMN"

Every fire DMs both user IDs the same digest.

Workspace-level email→SlackId map (per-recipient fan-out — recommended):

# rules.yaml — alongside the rules: list
slackUsers:
  alice@example.com: U01ABCDEFG
  bob@example.com:   U02HIJKLMN

rules:
  - tracker: jira
    filter: "..."
    notify:
      mailTo: assignee   # marker → email → Slack ID via the map above

See Routing model for the dispatch path.

Finding Slack user IDs

In the Slack desktop app: click a user's name → ... → Copy member ID. Format: U + 8-10 chars. The bot doesn't need to be added to a channel to DM a user — im:write covers it.

Message format

Slack mrkdwn (note: not standard Markdown):

• *bold* — single asterisks, not **bold**
• _italic_
• <https://example.com|label> — links with <url|label> syntax
• `code` — backticks
• :emoji_name: — emoji shortcodes (Slack auto-renders)

Preesta renders status (:hourglass_flowing_sand: In Progress, :white_check_mark: Done, …), priority (:red_circle: Urgent, :large_orange_circle: High, …), and other meta chips in mrkdwn natively.

Failure handling

Slack returns HTTP 200 even for app-level failures (with {ok: false, error: "..."} in the body). Preesta logs the error and moves on — one bad user ID never aborts the run. Common errors:

• channel_not_found — invalid user ID (typo or user is in a different workspace)
• not_in_channel — user has disabled DMs from the app
• account_inactive — workspace token revoked
• ratelimited — too many messages too fast (rare in normal digest cadence)

HTTP-level failures (timeouts, DNS errors) and JSON parse errors are logged + swallowed the same way.

Why personal DMs, not a #channel

Two reasons:

1. Per-recipient routing matters. A #bugs channel post can only contain one global view, but a rule with mailTo: assignee gives each assignee their slice. Channels lose that.
2. No incoming webhooks. Webhooks tie to a specific channel and don't accept user-targeting. Bot tokens do.

If you really want a channel digest, configure the bot to post into the channel (chat:write.public scope, channel ID in slackUserId: — Slack accepts channel IDs in chat.postMessage's channel field interchangeably with user IDs). It works but you lose the per-recipient story.