feat(mcp): scaffold MCP Prompts infrastructure (drafts, conversations, triage)

[dougborg]

Problem

frontapp_mcp_server/src/frontapp_mcp/prompts/ exists but is empty (just __init__.py). MCP Prompts are a first-class primitive (alongside tools and resources) for guided multi-step LLM workflows. They lower agent cognitive load by replacing freeform tool-call sequences with structured templates.

Sibling repo stocktrim built this out in PR #107 — prompts/ module + register_all_prompts() + domain-grouped prompt files + test scaffold.

Depends on

• chore(mcp): migrate fastmcp 2.x → 3.x (precondition for caching middleware, prompts, prefab UI) #108 (fastmcp 3.x — native prompts support)

Solution

Wire up the prompts infrastructure:

1. prompts/__init__.py — register_all_prompts(mcp) entry point that calls each domain's registration function
2. Domain-grouped prompt files: prompts/drafts.py, prompts/conversations.py, prompts/triage.py
3. Initial high-value prompts (start small, expand as patterns emerge):
   • compose_draft_reply — guided template for drafting a contextual reply (fetches the thread, suggests a tone, leaves slots for the human)
   • triage_inbox — walk through unassigned conversations and recommend tags/assignees
   • summarize_thread — structured thread summary for handoff
4. Test scaffold under frontapp_mcp_server/tests/prompts/

Files to add

• frontapp_mcp_server/src/frontapp_mcp/prompts/__init__.py (modify)
• frontapp_mcp_server/src/frontapp_mcp/prompts/drafts.py (new)
• frontapp_mcp_server/src/frontapp_mcp/prompts/conversations.py (new)
• frontapp_mcp_server/src/frontapp_mcp/prompts/triage.py (new)
• frontapp_mcp_server/src/frontapp_mcp/server.py — call register_all_prompts(mcp) during startup
• frontapp_mcp_server/tests/prompts/ (new directory)

Acceptance criteria

• uv run poe mcp-dev lists prompts in the inspector
• At least three prompts shipped (one per domain above)
• Manual smoke: invoke compose_draft_reply from inspector, get a usable scaffold
• Tests cover registration and at least one prompt's output structure

Reference

• feat(mcp): Setup MCP Prompts infrastructure (Issue #101) stocktrim-openapi-client#107 — exemplar