feat(slack): slash commands (Phase 3) + Block Kit interactions (Phase 2b)

[sookochoff]

Completes the Slack enhancement plan from docs/PRD-slack-enhancements.md (shipped with PR #58).

Depends on #58 (or rebases cleanly if that merges first).

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Phase 2b — Block Kit interactive components (inbound)

New MessageContent::Interaction variant (src/lib.rs)

Carries the result of a button click or select menu action:

• action_id, block_id — identifies which block element was actioned
• value, label — submitted value and human-readable label
• message_ts — ts of the original message, for thread correlation

Slack-only inbound — Discord, Telegram, and Webhook never produce this variant. The Display impl renders it as [interaction: action_id → value] so every existing text-processing code path in channel.rs receives readable plain text with zero adaptation. Exhaustive match enforcement means no adapter was silently missed.

interaction_callback wired in Socket Mode

• handle_interaction_event() registered via .with_interaction_events()
• Only SlackInteractionEvent::BlockActions is converted to InboundMessage; all other types (view submission, shortcuts, etc.) are acknowledged and logged at debug — no silent failures
• Each action in the payload becomes a separate InboundMessage so multi-action payloads are handled correctly
• message_ts threaded through both slack_message_ts and slack_thread_ts metadata so the agent replies in the correct thread
• trigger_id used as message ID (Slack guarantees uniqueness per interaction)

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Phase 3 — Slash commands

SlackCommandConfig (src/config.rs)

New config type, added as Vec<SlackCommandConfig> on SlackConfig only. TOML syntax:

[[messaging.slack.commands]]
command = "/ask"
agent_id = "main"
description = "Ask the agent a question"

[[messaging.slack.commands]]
command = "/task"
agent_id = "main"
description = "Kick off a background task"

Fully backwards compatible — field defaults to empty vec. Existing configs need no changes. Discord, Telegram, and Webhook configs are untouched.

command_callback wired in Socket Mode

• handle_command_event() registered via .with_command_events()
• 3-second ack requirement met: returns immediately; the real reply arrives via the normal respond() path
• Commands not in config get an ephemeral "not configured" reply — users get feedback instead of silence
• Command forwarded as MessageContent::Text("/ask <args>") — familiar format for the agent
• slack_command and slack_command_agent_id metadata keys allow per-command agent routing without requiring a separate binding entry per command

SlackAdapter::new() — new commands parameter

All four call sites updated (src/main.rs, src/api/messaging.rs, src/api/bindings.rs, src/config.rs). Commands converted to Arc<HashMap<String, String>> once at construction; read-only from callbacks.

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What is not changed

• Discord, Telegram, Webhook adapters — zero modifications
• OutboundResponse enum — unchanged (interaction replies use existing Text/Ephemeral/RichMessage variants)
• Binding resolution logic — unchanged; slack_command_agent_id metadata is advisory, existing bindings continue to work
• All non-Slack MessageContent match sites — only two arms added, no existing arms modified

Test results

• cargo check (lib + bin) — clean
• cargo test --lib — 43/43 pass

[sookochoff]

Both issues fixed in the force-push. Walkthrough:

1. Channel filter bypass in app_mention — fixed

Added the missing channel filter block to handle_app_mention_event immediately after the workspace filter, matching the exact logic in handle_message_event:

if let Some(allowed) = perms.channel_filter.get(&team_id_str) {
    if !allowed.is_empty() && !allowed.contains(&channel_id) {
        return Ok(());
    }
}

2. Fresh client per send_status call — fixed

Cached the SlackHyperClient and SlackApiToken on SlackAdapter itself, built once in new(). All six call sites (send_status, respond, broadcast, fetch_history, health_check, and start/auth_test) now call self.session() which does self.client.open_session(&self.token) — zero new allocations per call.

new() now returns anyhow::Result<Self> (the connector can fail to initialize) — all four call sites updated to handle the error with a tracing::error! log.

The socket mode listener gets its own separate client instance, which is correct — it manages a persistent WebSocket connection internally and needs to own that client for the lifetime of the connection. REST calls and the socket mode connection use separate clients but now there is only ever one of each.