feat: Add Slack notifications when Deploy PRs merge

[olerichter00]

Attempt to implement Claude Tag implementation in Duchamp as GitHub Action.

Description

Adds a reusable notify-deploy-slack GitHub Action and workflow that posts product-friendly deploy summaries to Slack when a Horizon Deploy PR (staging → release) merges. Messages highlight new features in the main post and group fixes and maintenance items in a thread reply.

When ANTHROPIC_API_KEY is provided, Claude (Haiku) batch-rewrites PR titles and descriptions into non-technical copy. Categorization, product areas, and Notion/Jira/flag links still come from rule-based parsing. On API failure, it falls back to heuristics — deploy notifications never block on AI.

Changes

• notify-deploy-slack action: parse deploy PR commits, enrich PR metadata, format Slack mrkdwn, post via bot token
• Optional Claude summarization (summarize-with-claude.ts) with rule-based fallback
• Reusable workflow, consumer template, and repo→channel config for artsy/volt → #product-amber
• Local dry-run script (no Slack token needed; set ANTHROPIC_API_KEY to preview Claude copy)
• Dry-run previews show copy source counts (e.g. 3 claude, 1 rules)
• Docs and build:action:notify-deploy-slack npm script

Example Slack notification

Dry-run of volt#11796 (./scripts/run-notify-deploy-slack-local.sh --dry-run 11796):

Main message

:rocket: A new batch of Volt changes just went live (<https://github.com/artsy/volt/pull/11796|PR>)!

New Features

Artworks: *Add Public-facing Routes for Studio* — Resolves [Public-facing routes for Studio](https://app.notion.com/p/artsy/Studio-Public-facing-routes-for-Studio-381cab…) (<https://github.com/artsy/volt/pull/11786|PR>)

Check the thread for fixes and improvements :thread:

Thread reply

Improvements & Maintenance

*AWS Storage Library Update* — Routine dependency update of the aws-sdk-s3 gem, with no visible changes (<https://github.com/artsy/volt/pull/11795|PR>)
*Test Tooling Update* — Routine update of the selenium-webdriver tool used for automated browser tests (<https://github.com/artsy/volt/pull/11794|PR>)
ArtOS: *Use Pills for the Collaborators Input in the Instagram Editor* — Use Palette pills as elements to display the collaborator usernames entered by the user. (<https://github.com/artsy/volt/pull/11797|PR>)

Remaining setup (after merge)

In duchamp (this PR):

• Add artsy/volt subscription in config/notify-deploy-slack.yml (#product-amber, project name Volt)
• Publish reusable workflow and action on main

Slack:

1. Create or reuse a Slack app with a bot token (xoxb-…) scoped with chat:write (incoming webhooks cannot post thread replies)
2. Invite the bot to #product-amber (or a test channel while validating)

Anthropic (optional, for better copy):

1. Get an API key from https://console.anthropic.com/settings/keys (or reuse Artsy's org-level ANTHROPIC_API_KEY from run-claude-review)
2. Add as repo or org secret ANTHROPIC_API_KEY

In artsy/volt:

1. Add repository secret SLACK_BOT_TOKEN with the bot token
2. Optionally add ANTHROPIC_API_KEY (same key as Claude PR review)
3. Copy templates/notify-deploy-slack.yml into .github/workflows/
4. Merge — notifications fire on the next merged Horizon Deploy PR

Optional — test before production:

• Local preview: ./scripts/run-notify-deploy-slack-local.sh --dry-run <deploy-pr-number>
• With Claude: export ANTHROPIC_API_KEY=sk-ant-... before running dry-run
• Post to test channel: pass slack-channel: "#your-test-channel" as a workflow input

Test plan

• yarn test .github/actions/notify-deploy-slack — 45 tests pass
• ./scripts/run-notify-deploy-slack-local.sh --dry-run 11796 — preview in tmp/, no Slack token required
• Same dry-run with ANTHROPIC_API_KEY — preview shows Copy source: N claude, …
• After merge: wire workflow into volt, set SLACK_BOT_TOKEN (+ optional ANTHROPIC_API_KEY)

Assisted-by: Claude:Sonnet-4.6 [claude-code]

[olerichter00]

Closing in favor of #101