feat: Collaboration API tools (comments, chat history) for agentic workflows

[grahama1970]

Problem

The Stitch web UI has rich collaboration features — comments on screens, chat threads on projects, and review workflows. However, the MCP server exposes zero tools for reading or writing collaboration data.

The 8 available tools are all design-generation focused:

create_project, get_project, list_projects, list_screens, get_screen,
generate_screen_from_text, edit_screens, generate_variants

No list_comments, add_comment, get_chat_history, or resolve_comment.

Impact

Agents can generate designs but cannot read human feedback left in Stitch's collaboration UI. This severs the feedback loop in agentic design workflows:

1. Agent generates mockup via SDK ✅
2. Human reviews in Stitch web UI and leaves comments ✅
3. Agent reads comments to understand feedback ❌ broken
4. Agent iterates based on feedback ✅ (if it had the feedback)

Today, agents must use external channels (separate chat tools, local files, custom UIs) to collect feedback — defeating the purpose of Stitch's built-in collaboration features.

Requested Tools

Tool	Description
list_comments	List comments on a project or specific screen. Returns author, text, timestamp, resolved status.
add_comment	Post a comment on a project or screen (e.g., agent posts review findings or asks clarifying questions).
get_chat_history	Read the chat/collaboration thread for a project.
resolve_comment	Mark a comment as addressed after the agent iterates on the feedback.

Use Case: Agentic Design Convergence Loop

With these tools, the full loop becomes:

1. agent: generate_screen_from_text → initial mockup
2. human: reviews in Stitch web UI, leaves comments
3. agent: list_comments → reads "make the sidebar wider, add dark theme"
4. agent: edit_screens with feedback from comments
5. agent: add_comment → "Addressed: sidebar widened, dark theme applied"
6. agent: resolve_comment on original feedback
7. human: reviews again, approves or leaves more comments
8. repeat until done

This keeps the entire design conversation inside Stitch rather than requiring external orchestration tools.

Environment

• @google/stitch-sdk 0.0.3
• Discovered while building an agentic mockup generation skill that composes Stitch with automated design review and human-in-the-loop feedback collection.