| name | kortix-slack |
| description | How to answer in Slack as a teammate. Covers the live plan-block stream (`slack step` with --detail/--output, `slack send` to finalize the answer), file uploads, posting to other channels/threads, reactions, search, message editing/deletion, and the tone the bot should use. Load this when the turn is triggered from Slack (the prompt mentions a Slack workspace/channel/thread, or `$SLACK_CHANNEL_ID` is set in the env), or when the user asks how to do anything in Slack. |
Your sandbox is wired into Slack. When a teammate `@`-mentions the bot or replies in a thread the bot owns, the platform spins up this session and hands you the message; your turn IS the Slack reply.
The slack CLI is on $PATH and just works — every call runs through the Kortix Executor, which resolves the Slack bot token server-side. There is no token in your sandbox and nothing to configure: don't look for $SLACK_BOT_TOKEN, don't reach for an MCP/HTTP workaround, just run the commands below. They are the full, supported surface (posting, file upload, history, reactions, search, edit/delete — all of it). Two patterns matter most:
slack step "..." — narrate progress. Updates the live plan block in the Slack thread as you go.slack send "..." — finalize the turn with your answer. This closes the plan block and posts the reply.
Everything else (slack history, slack react, slack send --file, slack search, …) is for when the task explicitly asks for it.
The Slack message you're replying to has a live "plan block" attached. Each `slack step` you emit appears as a new checkpoint in that block in real time. Users can see what you're doing without waiting for the final answer.
slack step "<title>" — emit a checkpoint
Call this before each major step of your work. Keep titles short, human, and present-tense. A few per task — not one per shell command.
slack step "Reading the incident logs"
slack step "Cross-referencing with the deploy timeline"
slack step "Drafting the post-mortem"
--detail "<subtitle>" — short context line under the title
Use --detail to add a one-line subtitle that explains what specifically you're doing in this step. Shown while the step is in_progress.
slack step "Reading the incident logs" --detail "Last 24h, severity >= warn"
--output "<result>" — concrete result attached to the PREVIOUS step
When you start a new step and the previous one produced a concrete result, surface it with --output. It attaches to the step that's closing — the one transitioning to complete.
slack step "Cross-referencing with the deploy timeline" \
--output "Found 47 ERROR lines clustered around 14:32 UTC"
slack step "Drafting the post-mortem" \
--output "3 candidate deploys in the window; api@a3f1 looks suspicious"
Inline links inside --detail / --output
Use Slack mrkdwn link syntax <https://… |label> (NOT Markdown [label](url)). Slack server-parses these into proper rich-text link elements rendered inside the task card:
slack step "Reading the incident logs" \
--detail "Pulling from <https://datadog.example.com/dash/api-errors|Datadog API errors>"
slack step "Cross-referencing the timeline" \
--output "Tied to <https://github.com/acme/api/commit/a3f1|api@a3f1> — auth middleware"
--source URL|TITLE — citation footer (repeatable)
Attach structured citations to the closing task. Slack renders them as a sources strip under that task's card. Pass multiple --source lines separated by newlines (use shell heredoc or repeat the flag in a wrapper).
slack step "Drafting the post-mortem" \
--output "3 candidate deploys" \
--source $'https://github.com/acme/api/commit/a3f1|api@a3f1
https://datadog.example.com/dash/api-errors|Datadog dashboard'
Up to 8 sources per task, titles auto-trim at 80 chars.
So the natural pattern, end-to-end, looks like:
slack step "Reading the incident logs" --detail "Last 24h, severity >= warn"
slack step "Cross-referencing the deploy timeline" \
--output "47 ERROR lines around 14:32 UTC" \
--detail "Walking back from the first error"
slack step "Drafting the post-mortem" \
--output "Pinned to api@a3f1 — auth middleware change" \
--detail "Writing root cause + remediation"
slack send "It was api@a3f1 — the new auth middleware drops the trace header on retries. Reverting now."
Rules
- Use
slack step to mark phase transitions, not every shell call. ~3–6 per turn is right for most tasks; one per bash is noise.
- Set
--detail and --output once per step. Re-sending them for the same step appends rather than replaces — surprising and ugly.
- Keep them short.
--detail and --output get truncated at 500 chars upstream; aim for one tight sentence.
- Don't
slack step after you've called slack send. The plan is closed. Further steps drop silently.
### The ~5-minute idle timeout (READ THIS — it's the #1 cause of false "errors")
Slack enforces a hard ~5-minute idle timeout on a streaming turn. The clock is idle time since the last stream update, not total turn length — and it is not bypassable from Slack's side. Every slack step you emit is a stream update that resets the timer to zero. If more than ~5 minutes pass with no update, Slack kills the turn and paints a red error in the thread — even though your agent is alive and working fine. The work usually still completes in the background; the user just sees a scary "failed" state. (Same root cause as a finished plan block getting stuck on "in_progress" — the stream got severed before the final slack send.)
The platform runs a safety-net heartbeat (a watchdog touches any quiet-but-alive stream every ~3 min so Slack doesn't auto-fail it). Treat that as a backstop, not an excuse to go silent: it only paints a generic "Working on it…" tick, it doesn't help if the watchdog is down/lagging, and a wall of nothing for minutes is bad UX. You keeping the stream warm with real checkpoints is still the primary fix.
So: a turn doesn't fail because the work is slow. It fails when it goes quiet. Don't go quiet.
Rules to never trip it
### `slack send ""` — plain-text answer
For a one-liner, post directly:
slack send "Reverted api@a3f1. Errors are back to baseline — auth header is now preserved on retry."
This finalizes the live stream and renders the message below the plan block.
slack send --blocks-file <path> — Block Kit answer (preferred for structure)
When the response has real structure — sections, headers, lists, links, citations — ship it as Block Kit. Slack accepts a closing blocks chunk on chat.stopStream, so the rich layout renders inline below the plan block. Always pair --blocks-file (or --blocks) with --text for the notification fallback.
Write the JSON to a temp file, then send:
cat > /tmp/answer.json <<'EOF'
[
{ "type": "header", "text": { "type": "plain_text", "text": "Incident summary" } },
{ "type": "section", "text": { "type": "mrkdwn", "text": "*Root cause:* <https://github.com/acme/api/commit/a3f1|api@a3f1> — the new auth middleware drops the trace header on retries." } },
{ "type": "divider" },
{ "type": "section", "fields": [
{ "type": "mrkdwn", "text": "*Impact*\n14:32–14:51 UTC\n~3% of API requests" },
{ "type": "mrkdwn", "text": "*Action*\nReverted, deploying now" }
] },
{ "type": "context", "elements": [
{ "type": "mrkdwn", "text": "Sources: <https://datadog.example.com/dash/api-errors|Datadog> · <https://github.com/acme/api/pull/8421|Revert PR>" }
] }
]
EOF
slack send --text "Reverted api@a3f1 — root cause was the auth middleware" --blocks-file /tmp/answer.json
Use Block Kit when ANY of these apply:
- The answer has 2+ distinct sections (root cause + impact + action, or summary + details + sources).
- You're presenting comparisons, tables, or lists of items.
- The answer should cite multiple sources prominently.
- The response benefits from a clear title (use a
header block).
Use plain slack send "..." when the answer is short prose with no structure.
Block Kit cheat sheet
Common block types the agent uses most:
| Block | Use for |
|---|
header (plain_text) | Title of the answer |
section (mrkdwn) | Most prose, including `<url |
section with fields | 2-column key/value layout (max 10 fields) |
divider | Visual break between sections |
context (mrkdwn) | Small footer text, sources, timestamps |
image (image_url + alt_text) | Charts, screenshots — needs a public URL |
actions (buttons / select menu) | Inline interactivity for follow-ups |
carousel (of card elements) | Side-scrollable gallery — see below |
Carousel of cards — for presenting a list of choices/items
When the answer is a list of things the user might pick between or browse (deploy candidates, repo search hits, scheduled meetings, design variants), a carousel of cards reads way better than a markdown list. Each card has an icon, a hero image, title/subtitle, body, and one or more buttons.
Important constraints (Slack rules, not ours):
- Cards live ONLY inside a
carousel block.
- Cards support
body (mrkdwn) and actions (buttons / select menus) — they do NOT support input / radio_buttons / checkboxes. If you need form inputs, use the question tool instead.
- Each card's button click fires a
block_actions interaction; the platform routes it back as a follow-up Slack message (Picked: <button label>) into the same thread, the agent's next turn starts from that.
- 2–10 cards per carousel.
Example — presenting 3 deploy candidates:
[
{ "type": "section", "text": { "type": "mrkdwn", "text": "*Three deploy candidates* — pick one to ship:" } },
{
"type": "carousel",
"elements": [
{
"type": "card",
"block_id": "deploy_a3f1",
"icon": { "type": "image", "image_url": "https://github.com/acme.png?size=36", "alt_text": "acme" },
"title": { "type": "mrkdwn", "text": "*api@a3f1* — Production-ready" },
"subtitle": { "type": "mrkdwn", "text": "2 commits ahead of main · ✓ tests pass" },
"hero_image": { "type": "image", "image_url": "https://opengraph.githubassets.com/1/acme/api", "alt_text": "diff" },
"body": { "type": "mrkdwn", "text": "Auth middleware retry fix + new metric. Safe to ship — small surface area, full coverage." },
"actions": [
{ "type": "button", "style": "primary", "text": { "type": "plain_text", "text": "Deploy this" }, "action_id": "deploy_a3f1", "value": "a3f1" },
{ "type": "button", "text": { "type": "plain_text", "text": "View diff" }, "url": "https://github.com/acme/api/compare/main...a3f1" }
]
},
{ "type": "card", "block_id": "deploy_b27e", "title": { "type": "mrkdwn", "text": "*api@b27e* — Needs review" }, "subtitle": { "type": "mrkdwn", "text": "12 commits ahead · ⚠️ 1 failing flake" }, "body": { "type": "mrkdwn", "text": "Bigger release: rate-limiter rework + Stripe webhook fix. Flake is in webhook tests." }, "actions": [ { "type": "button", "text": { "type": "plain_text", "text": "Deploy this" }, "action_id": "deploy_b27e", "value": "b27e" }, { "type": "button", "text": { "type": "plain_text", "text": "Hold" }, "style": "danger", "action_id": "hold_b27e", "value": "b27e" } ] },
{ "type": "card", "block_id": "deploy_c901", "title": { "type": "mrkdwn", "text": "*api@c901* — Hotfix only" }, "subtitle": { "type": "mrkdwn", "text": "1 commit · auth header preserve" }, "body": { "type": "mrkdwn", "text": "Minimal fix for the 14:32 incident. Lowest risk." }, "actions": [ { "type": "button", "style": "primary", "text": { "type": "plain_text", "text": "Deploy this" }, "action_id": "deploy_c901", "value": "c901" } ] }
]
}
]
Ship it the same way as any Block Kit answer:
slack send --text "Pick a deploy candidate" --blocks-file /tmp/candidates.json
When to reach for carousel:
- 2–6 items the user is choosing between, each with non-trivial context (subtitle, body, hero image).
- The agent expects the user's button click to become the next prompt, not a fill-in form.
When NOT to:
- For mid-turn structured input (use
question instead — carousel can't host inputs).
- For 1 item (just a section) or 7+ items (split, paginate, or summarize).
- For a quick yes/no (use
question with single-select).
Full Block Kit reference: https://docs.slack.dev/reference/block-kit/blocks/
Tone (applies to either mode)
Reply like a colleague messaging on Slack:
- No preamble. Don't open with "Sure!" / "I've taken a look and…". Get to the answer.
- Slack mrkdwn.
*bold* (single asterisks), _italic_, `code`, ```code blocks```. Markdown-style **bold** renders as literal asterisks — don't use it.
- Short. A few sentences > a wall of text. Use bullet lists for ≥3 items.
- Link with
<url|text>. Slack's syntax, not Markdown [label](url).
- No XML / no "Here's a summary:" headers. This is a chat message, not a report.
One slack send per turn
Each turn finalizes exactly one stream. Don't call slack send twice — the second call drops silently because the stream is already closed. If you need to deliver multiple things, fold them into one Block Kit message or use slack send --channel ... for sibling posts.
### Use opencode's built-in `question` tool — Slack renders the form
Rule: if your reply contains a question, call the question tool. Never put questions inside slack send.
slack send finalizes the turn and closes the live stream — once it fires, the user can only reply with a free-text message. If you posted multi-choice questions via slack send, the answers come back as unstructured prose and you have to re-parse them. Don't.
opencode ships a native question tool. Call it the same way you would in any other host (dashboard, TUI). When the turn is Slack-triggered, the sandbox automatically catches the question.asked event and renders a Block Kit form (radio buttons / checkboxes / a free-text box) in the same thread. The user submits → opencode resumes your tool call with their answers. Zero Slack-specific glue from your side.
| When you want to… | Use |
|---|
| Ask a question or set of questions | question tool |
| Deliver the final answer / summary | slack send |
| Show progress along the way | slack step |
| Post a separate message to another channel | slack send --channel ... |
Calling the question tool
Per opencode's schema (Array<QuestionInfo>):
{
"questions": [
{
"question": "Which environment should I deploy to?",
"header": "Environment",
"options": [
{ "value": "prod", "label": "Production" },
{ "value": "staging", "label": "Staging" },
{ "value": "dev", "label": "Dev (sandbox)" }
],
"multiple": false,
"custom": true
}
]
}
Multiple questions in one call:
{
"questions": [
{
"question": "Priority for next sprint",
"header": "Priority",
"options": [
{ "value": "auth", "label": "Finish the auth migration" },
{ "value": "billing", "label": "Ship metered billing v2" },
{ "value": "ingest", "label": "Rebuild the ingest pipeline" }
],
"multiple": false
},
{
"question": "What risks should I flag?",
"header": "Risks",
"options": [
{ "value": "rollback", "label": "Rollback complexity" },
{ "value": "perf", "label": "Performance regressions" },
{ "value": "data", "label": "Data migrations" }
],
"multiple": true
},
{
"question": "Any constraints I should know about?",
"header": "Constraints",
"options": [],
"custom": true
}
]
}
Reading the answer
The question tool's return value is answers: string[][] — one array per question, in the same order you sent them. Each inner array contains every value the user picked, plus any free-text they typed into the custom field (concatenated at the end).
[
["auth"],
["rollback", "data"],
["Vendor X freeze ends Tuesday."]
]
Rules
- Use the
question tool, not chat prose. A free-text reply loses structure.
- Keep it focused. 1–3 questions per call. If you need more, split into multiple
question calls across the turn (each is its own pause).
- Form expires after 15 minutes. If the user doesn't click Submit, the form resolves with empty arrays — opencode treats that as a reject; the tool returns and you can adapt.
- The Stop button still works. A user who clicks 🛑 Stop aborts the turn; the form is closed and the tool returns empty.
- Skip trivial yes/no when context implies the answer. Use judgment — the form is for real decisions, not "are you sure?" rituals.
### Uploading files: `slack send --file --channel `
File upload is fully supported — slack send --file is the way. When the work produces an artifact (a PDF, a CSV, a report, a diff, a screenshot), upload it with --file instead of pasting the contents or improvising. Do not conclude "uploads aren't supported", and do not reach for the executor/MCP, a manual files.getUploadURLExternal call, or an HTTP-host-a-link hack — --file already does the multi-step upload for you, server-side. It requires a --channel and (typically) a --thread so it lands under the answer:
slack send \
--channel "$SLACK_CHANNEL_ID" \
--thread "$SLACK_THREAD_TS" \
--file /workspace/output/report.md \
--text "Full report ↓"
$SLACK_CHANNEL_ID and $SLACK_THREAD_TS are pre-set on Slack-triggered turns. Use them.
Note: slack send --file ... posts a separate message — it does NOT count as the turn's finalizing answer. Combine it with a regular slack send "..." to also close the stream:
slack send --channel "$SLACK_CHANNEL_ID" --thread "$SLACK_THREAD_TS" \
--file /workspace/output/report.md --text "Full report attached."
slack send "Pulled 12,847 sign-ups, grouped by source. CSV above."
Reach for these only when the task explicitly asks for them.
Read prior thread context
slack history --channel "$SLACK_CHANNEL_ID" --thread "$SLACK_THREAD_TS"
slack thread --channel "$SLACK_CHANNEL_ID" --ts "$SLACK_THREAD_TS"
React to a message
slack react --channel "$SLACK_CHANNEL_ID" --ts "$SLACK_TRIGGER_TS" --emoji "white_check_mark"
Post to a different channel (announcements, cross-posts)
slack send --channel "C0123ABCD" --text "Heads up: rolled api@a3f1 forward."
Edit / delete a message you posted earlier
slack edit --channel "$SLACK_CHANNEL_ID" --ts "<msg_ts>" --text "Updated answer."
slack delete --channel "$SLACK_CHANNEL_ID" --ts "<msg_ts>"
Search the workspace
slack search --query "deploy api@"
Look up users / channels
slack users
slack user --user "U0123ABCD"
slack channels
slack channel-info --channel "C0123ABCD"
slack me
Download a file shared in the thread
slack file-info --file "F0123ABCD"
slack download --url "<file.url_private>" --out /workspace/incoming/x.png
Full help: slack help.
- **`*bold*` not `**bold**`.** Slack uses single asterisks. Double-asterisk markdown renders as literal asterisks.
- **`--detail` and `--output` are append-not-replace per step.** Set each only once on the step that owns it. If you need to revise, advance to a new step.
- **`slack step` after `slack send` drops silently.** Plan block is closed once the answer ships. Always send the answer last.
- **`slack send --file` does NOT finalize the stream.** It posts a separate file message. Follow it with a regular `slack send "..."` to close the turn.
- **`$SLACK_CHANNEL_ID`, `$SLACK_THREAD_TS`, `$SLACK_TRIGGER_TS` are pre-injected on Slack turns.** Use them — don't hard-code IDs.
- **Stay in the thread.** Unless the task explicitly says "post in #channel-X", everything goes in the originating thread. Cross-posting to other channels needs a real reason (incident broadcast, scheduled digest).
- **The user can hit Stop.** A red Stop button sits under the plan block; the user can click it any time. If you see the turn end abruptly, that's why — don't retry automatically.
