Decision 111: a Slack message the pipeline accepts is acknowledged on that message, best-effort, with Slack's own palette
- Status: proposed
- Date: 2026-09-08
- Work item: issue-325
- Deciders: jc1993 (the ask), the-loop (design); MadaraUchiha-314 (owner, at the PR)
- Refines: decision-103 (through the ledger, never around it), the issue-84 contract (
routing.reactions: on by default, best-effort, ids only)
Context
Issue-84 gave the dispatcher a visible acknowledgment on GitHub: 👀 when an event is dequeued, 🎉 when the dispatch lands, 😕 when it fails — best-effort, on by default, reaction-only. Issue-245 and issue-309 then made Slack a channel an operator can drive the loop from: a reply in a bound thread is authorized, classified, recorded on the ledger and acted on. The acknowledgment did not follow the reply: target_from_event answers None for anything that is not GitHub, and the Slack channel never called reactions.add. @jc1993's case is the phone: after replying, the only feedback is a posted message minutes later, and until then the reply may or may not have been seen.
Three questions had to be settled: where the acknowledgment sits in the pipeline, which emoji, and how much of the GitHub reactor to reuse.
Decision
| # | What was chosen | Why |
|---|---|---|
| D1 | The acknowledgment sits after the last refusal and before the record. received is added once the message passed map → drop-own → authorize → classify → grant, and before the ledger write; completed / error after the action, from the outcome the pipeline already computes. A dropped message gets no reaction. | An acknowledgment is a statement that the-loop will act on this. Placed any earlier it would confirm the bot's presence to a stranger or acknowledge a message that is then dropped; placed after the record it would lag the very thing the operator is waiting to know. Silence on a drop mirrors the ticket (a drop writes nothing there either) and issue-322's a refusal leaves no mark. |
| D2 | Its own config block, channels.slack.reactions, mirroring routing.reactions' contract rather than sharing its values. enabled (default true), three states, "" skips one. | The two palettes differ: GitHub's is a fixed eight (hooray, not tada), Slack's is open and per-workspace. Sharing the names would force one surface to a wrong or missing emoji; sharing the shape — on by default (the owner's PR #85 call: visibility out of the box is the point), a state per lifecycle moment, best-effort — keeps the two readable side by side. The block lives under channels.slack because it is a fact about that channel's token and scope, not about routing. |
| D3 | Slack's defaults are eyes, white_check_mark, warning. | Issue-84 asked for ✅ and ⁉️ and settled for 🎉 and 😕 because GitHub has neither. Slack has ✅; it is the mark a phone reader recognises fastest as done. ⚠️ is chosen over ⁉️ for the same legibility reason — a failure should look like a failure. 👀 is kept: it is what the operator already knows from GitHub. |
| D4 | completed means the pipeline's own action landed, per event type. A work-item.reply is complete when recorded and delivered; a relayed gate.feedback / control.command when its unmarked record is on the ledger; a kickoff when the issue exists and the thread is bound. | The pipeline does not observe the ledger's ingress locking a gate or starting a session, and a ✅ that claimed it would be a lie the operator acts on. What the pipeline can vouch for is that the message reached the ticket the loop reads — which is the contract decision-103 already makes for a relayed reply. The gap is named in the requirements' Out of scope, with the seam a later item would use (subscribe the channel to the outcome event). |
| D5 | A method on the channel, not a reactor module. SlackBotChannel.react(reply, state) with the channel's own client and token rule; the pipeline decides when. | reactions.py is a RoutedEvent → gh argv reactor with a GitHub palette; the Slack call is one SDK method. A shared abstraction over two calls that share nothing but a lifecycle vocabulary is the kind of layer minimalism refuses. The contract — never raises, ids-only events — is copied in words, not in code. |
Consequences
Good. The operator on a phone sees 👀 within a poll interval (or instantly over Socket Mode) and ✅ / ⚠️ when the pipeline is done — on the message they typed, without opening GitHub. The two surfaces' acknowledgments read alike. Nothing about what a message may become, who may speak, or where the record lands changes.
Costs, accepted. One more scope on the bot token (reactions:write); without it, every accepted message costs one channel.reaction_failed warning until the operator adds the scope or sets enabled: false — loud by design, as the missing-gh warning is. One more Slack API call per accepted message (two when the action finishes), in the pipeline's own thread, before the record: on a Slack outage the SDK's 30-second timeout is the worst-case delay before the record is written — the same exposure the ledger write already has on a GitHub outage, and it never changes the outcome. The ledger's ingress still acknowledges the relayed record on GitHub, so a gate answer from Slack ends up with 👀 in two places, which is the mirror the ticket asked for.
Alternatives considered
| Alternative | Why not |
|---|---|
Reuse routing.reactions' values for Slack | hooray and confused are not Slack emoji names; the operator would have to choose names that exist on both, or one surface would silently fail |
Extend GitHubReactor with a Slack target (target_from_event for a slack provider) | The reactor is built around a routed GitHub event and a gh argv; a Slack reply is an InboundReply in another package with its own client. The seam is the pipeline, not the dispatcher |
| React on the drop too (a ❌ for an unauthorized reply) | Confirms to a stranger that the bot reads the thread, and marks a message the-loop deliberately leaves no record of |
completed only when the ledger's ingress finishes (the gate locked, the session started) | The pipeline cannot see it; faking it means a ✅ on an approval the gate then refused. Left as a seam for a later item |
| Remove 👀 when adding ✅ | GitHub keeps both; a second write to remove a decoration buys nothing |
Default enabled: false | The owner's PR #85 decision for GitHub was the opposite, and the ticket asks for the mirror; the fail-closed defaults that matter (channels.slack.enabled: false) already gate everything |