kortix-slack

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"
# ... do the work ...
slack step "Cross-referencing the deploy timeline" \
  --output "47 ERROR lines around 14:32 UTC" \
  --detail "Walking back from the first error"
# ... do the work ...
slack step "Drafting the post-mortem" \
  --output "Pinned to api@a3f1 — auth middleware change" \
  --detail "Writing root cause + remediation"
# ... do the work ...
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

• Never go >~4 minutes without a slack step. Treat 4 min as your budget; post before you spend it. A step is cheap — emitting one extra is free, tripping the timeout is not.
• Before any long-running operation, post a step first. Anything that can take minutes — git clone, pnpm install, a test suite, a build, pnpm preview, deep web research, a big LLM call, a task/subagent — gets a slack step immediately before you start it, so the timer is fresh going in.
• Break long single operations into narrated phases. Don't do "clone + install + typecheck + test" as one silent 12-minute block. Step between each: slack step "Installing deps" → slack step "Running typecheck" → slack step "Running tests". Each one resets the clock and reads better.
• For a genuinely long single command (one >4-min step with nothing to narrate), stream a heartbeat from a background loop so the timer keeps resetting while it runs:

  # keep the Slack stream warm during a long blocking command
  ( while sleep 200; do slack step "Still working… (running tests)"; done ) &
  HB=$!
  pnpm test            # the long thing
  kill "$HB" 2>/dev/null   # stop the heartbeat as soon as it returns
  

  Kill the heartbeat the instant the command returns, and never leave a heartbeat running after slack send (steps after send drop silently, and a stray background loop is a leak — see the "stop long-running processes before you finish" rule).
• It's idle-time, not call-count. Ten steps in one minute then six minutes of silence still trips it. Spacing is what matters, not volume — but err toward more frequent updates on long tasks; it's the single biggest reliability win.

### `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",          // short label (max 30 chars)
      "options": [
        { "value": "prod",    "label": "Production" },
        { "value": "staging", "label": "Staging" },
        { "value": "dev",     "label": "Dev (sandbox)" }
      ],
      "multiple": false,                 // false = radio, true = checkboxes
      "custom":   true                   // true = also show a free-text box
    }
  ]
}

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).

// for the 3-question example above
[
  ["auth"],                              // single-select
  ["rollback", "data"],                  // multi-select
  ["Vendor X freeze ends Tuesday."]      // custom text only
]

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.