Add links and Comment quotes to MCP reads #343

Parent

#328. Related: #230, #336

What to build

A person asks their AI app "Where did we decide the venue budget?". The answer cannot link there, because no read tool returns a link. The app also cannot see which sentence a Comment quotes, so it misreads replies such as "too high".

After this change, get_outline and read_document return heading links, and list_chat_rooms returns chat links. read_chat_thread shows each Comment's quote.

Acceptance criteria

• One module in apps/hocuspocus.server/src/lib/ exports buildDocumentUrl(appUrl, slug) and buildHeadingUrl(documentUrl, tocId | null). buildDocumentUrl encodes the slug. buildHeadingUrl encodes the toc-id.
• The digest's sectionUrl is deleted. Digest tests pass with unchanged URLs.
• create_document and the digest's withResolvedName use buildDocumentUrl.
• get_outline gives each node a url, or url: null when section_id is null.
• read_document carries url: the heading link with section_id, else the document link.
• list_chat_rooms gives each room a url from buildChatActionUrl. A cold open of it opens that heading chat.
• Links appear in structuredContent and in the text, outside the data frame.
• read_chat_thread shows a text Comment as (comment on: "<quote>"), capped at 200 characters, with line breaks as spaces. A media Comment shows (comment on media). No src, html, caption or preview leaves the server.
• From metadata, readThread selects only named paths (comment->>kind, comment->>content), never the whole object.
• Tool descriptions, docs/mcp/reference.md and apps/hocuspocus.server/API.md §MCP connector name the new fields.

Blocked by

• Land a heading link on its heading, even when the heading is folded or filtered #338 — until it lands, a cold-opened heading link opens the top of the pad.

Agent brief

Type: AFK.

• Model the helpers on buildChatActionUrl (apps/hocuspocus.server/src/lib/push/chatActionUrl.ts). The module imports nothing, so tests load it without Redis.
• The browser writes Comment JSON (apps/webapp/src/api/messages/sendCommentMessage.ts). So one pure function in modules/mcp/domain/ type-checks it.
• Rules: apps/hocuspocus.server/CLAUDE.md §MCP Connector and §Testability Seams. AGENTS.md §Test Policy (c): one formatter unit test, proved by sabotage.
• Verify: bun test src/modules/mcp tests/unit/contentChangeDigest.test.ts, typecheck, lint, format. Open each returned url in a fresh profile.

Out of scope

• The via connected app tag — Mark MCP chat posts with a fixed connected-app metadata key #336.
• Landing a cold-opened ?id= link — Land a heading link on its heading, even when the heading is folded or filtered #338.