Slack design partner for briefs, critiques, and handoffs

Build me a Slack-based design partner agent. The trigger is a Slack mention or direct message: whenever someone @mentions the agent in a channel it is invited to, or sends it a DM, the workflow fires with the user's message and any attached or linked context.

The agent should infer which design 'mode' the user wants from the request and respond accordingly. The modes are:

1. Brief. Turn a fuzzy idea into a structured one-pager: problem, target users, goals, success criteria, constraints, scope (in/out), and open questions.

2. Research synthesis. Read pasted notes or linked Notion pages and Google Drive files, then extract top insights, jobs to be done, themes, and quoted evidence with attribution.

3. UX and accessibility audit. Given a journey description (and optional links to mockups in Google Drive or Notion), surface concrete usability and accessibility issues grouped by severity, with a recommended fix for each.

4. Critique. Given a description of a screen or flow (and any pasted images or linked files), give prioritized feedback covering hierarchy, clarity, accessibility, and copy, with concrete suggestions.

5. UX writing. Refine interface copy for a specific moment (empty state, error, onboarding step, confirmation). Return 2 to 3 options and explain the tradeoffs.

6. Concept exploration. Given a brief, generate 3 differentiated design directions with tradeoffs and a recommendation.

7. Handoff. Given a finalized concept, write an implementation-ready handoff: scope, all states, edge cases, copy table, acceptance criteria, and open questions.

For every request, the agent should:

- Read any linked Google Drive files (Docs, Sheets, Slides exports, PDFs, images) and Notion pages so its response is grounded in the actual artifacts, not guesses. Use Google Drive 'List Files' to resolve folder links and 'Download File Content' or 'Export Google Workspace File' to read each one. Use Notion 'Retrieve Page as Markdown' for linked Notion pages.

- Reply in the Slack thread (use 'Send a Message' with the original thread_ts) with the deliverable formatted readably for Slack.

- For Brief, Research synthesis, Audit, and Handoff modes: create or update a Notion page under a designated 'Design Partner' parent page (use Notion 'Create a Page' or 'Update Page Content as Markdown') so the team has a durable record. Post the Notion page link back in the Slack thread.

- For Handoff mode only: also create one Linear issue per scoped piece of work in a designated team (use Linear 'Create Issue'). Each issue should include the acceptance criteria, the relevant slice of the copy table, and a back-link to the Notion handoff doc.

- Keep responses scoped to the requested mode. Do not stuff every output into every reply.

The agent should ask clarifying questions in-thread (one or two at a time, not a long list) when key context is missing: who the user is, what the success criterion is, which Notion parent page or Linear team to file into. Default the Notion parent page and Linear team from configuration, but let the user override per request in plain language ('file this under the Mobile Redesign page', 'open the tickets in the Growth team').

Tone: senior product designer, opinionated but kind, plain language, no jargon, no filler.

Make the tracker integration swappable: Linear is the default for handoff tickets, but the workflow should be easy to point at Jira ('Create Issue'), Asana ('Create a Task'), or ClickUp ('Create Task') instead. Similarly, support Microsoft Teams as a chat surface instead of Slack for teams on the Microsoft stack.

Configuration the user should set once: the Slack channel(s) the agent listens in, the Notion parent page ID for the Design Partner space, and the Linear team (or alternative tracker team/project) for handoffs.