LAM-1287: Add notification logging to ClickHouse and Slack subscription for reports

[laminar-coding-agent]

Summary

• ClickHouse notification_log table: New migration (27) creates notification_log table to record every email and Slack notification with full details (recipient, subject, body, status, error) for auditing and inspection. Records are ordered by (workspace_id, created_at) with a 90-day TTL.
• Notification logging in app-server: NotificationHandler now writes a log entry to ClickHouse after each email/Slack send, capturing both successes and failures per recipient. Added workspace_id to NotificationMessage for queryability.
• Slack report delivery: Report generator now sends Slack notifications (formatted with Block Kit) alongside emails when Slack targets are configured. Added ReportSummary variant to SlackMessagePayload and get_report_target_slack_channels DB query.
• Frontend Slack subscription for reports: Reports UI now shows both an email toggle and a Slack channel selector per report. Uses discriminated-union Zod schemas for type-safe opt-in/opt-out of EMAIL and SLACK target types. Slack integration card shown when not connected.

Changed files

Backend (Rust)

• app-server/src/ch/notification_log.rs — new CH insert module for notification_log
• app-server/src/ch/mod.rs — register notification_log module
• app-server/src/db/reports.rs — add get_report_target_slack_channels query
• app-server/src/notifications/mod.rs — add ClickHouse logging after send, add workspace_id to message
• app-server/src/notifications/slack.rs — add ReportSummary payload variant with Block Kit formatting
• app-server/src/reports/generator.rs — push Slack notifications for reports alongside emails
• app-server/src/main.rs — pass ClickHouse client to NotificationHandler
• app-server/src/signals/postprocess.rs — add workspace_id field to notification message

Frontend (TypeScript)

• frontend/lib/clickhouse/migrations/27_notification_log.sql — new ClickHouse migration
• frontend/lib/actions/reports/index.ts — discriminated union schemas for EMAIL/SLACK opt-in/opt-out
• frontend/components/workspace/reports/index.tsx — add Slack integration, channels, and handlers
• frontend/components/workspace/reports/reports-list.tsx — email toggle + Slack channel selector per report
• frontend/components/workspace/workspace.tsx — pass Slack props to reports component

Test plan

• Verify ClickHouse migration applies on startup (notification_log table created)
• Send a report email and verify a row appears in notification_log with channel=email
• Configure a Slack target for a report and verify Slack message is delivered
• Verify notification_log row for Slack delivery with channel=slack
• Test email opt-in/opt-out from reports UI
• Test Slack channel subscribe/unsubscribe from reports UI
• Verify removing Slack integration cleans up report Slack targets

🤖 Generated with Claude Code

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Note

Medium Risk
Adds new ClickHouse writes in the notification hot path and expands report delivery to Slack; failures or schema mismatches could affect notification processing and increase operational load.

Overview
Adds notification auditing by introducing a ClickHouse notification_log table (90-day TTL) and writing per-send entries for both email and Slack, including success/error status, recipient, and rendered body/blocks.

Extends report delivery to support Slack: report generation now reads Slack targets, enqueues report_slack messages with a new SlackMessagePayload::ReportSummary (Block Kit formatting), and the notifications worker now carries workspace_id on NotificationMessage (resolved for alerts and passed through for reports).

Updates the reports UI and API payloads to manage both email and Slack subscriptions: per-report email toggle plus Slack channel selector/unsubscribe, with server-side Zod validation via discriminated unions and one Slack channel enforced per report.

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