ADR 0010 — Slack as the two-way daily surface (Socket Mode bridge)

Context

The daily loop needed a push channel (roadmap 1.3) and Kelyn wants to talk back — record verdicts, request drafts, query memory — from the same place the digest lands. Options: email (one-way), a web dashboard (deferred, Tier 6), or Slack.

Inbound Slack requires receiving events. The Events API over HTTP needs a public HTTPS endpoint — wrong for a pipeline that runs on a laptop. Socket Mode holds an outbound websocket instead: no ingress, no tunnel.

Decision

slackbridge/ package, split by dependency weight:

Push path is dependency-free. SlackClient speaks the Web API with httpx (same pattern as the OpenRouter client): chat.postMessage with Block Kit bodies for the digest and next-actions pushes. Works in cron with zero optional deps.
Pull path is an optional extra. The Socket Mode listener (python -m slackbridge) needs uv sync --extra slack (slack-sdk), import-guarded like anthropic/mem0. It turns messages (verdict 123 apply, actions, prep 45, recall gitlab) into the same Storage/runner/memory calls the CLI and MCP server make — a third thin adapter, zero business logic.
Safety rules in the listener: ack every envelope before processing (Slack redelivers un-acked envelopes — that would double-execute billed commands); ignore bot messages and subtypes (loop protection); honor SLACK_CHANNEL as a conversation filter; every command handler catches its own errors and replies with a message — a typo can never kill the daemon.
Karani drafts, Kelyn sends. The bridge posts materials and worklists into Slack; it never messages anyone else or submits anything on his behalf (vision non-goals).

Consequences

Positive: digest, fast-lane alerts, and follow-up reminders arrive where Kelyn already is; reacting takes one reply, feeding verdicts and memory with near-zero friction.
Positive: command dispatch is a pure function (handle_command) — fully testable without slack-sdk or a socket.
Negative: a third surface to keep in sync with CLI/MCP. Mitigation: same rule as ADR 0008 — capability lands in Storage/runners first.
Negative: Socket Mode needs a long-running process. Acceptable — it can run under launchd next to the cron loop; pushes still work when it’s down.
Neutral: requires a one-time Slack app setup (Socket Mode on, chat:write + im:history scopes, message.im event subscription); documented in slackbridge/listener.py and .env.example.