[POC] MCP Apps: interactive lineage via get_lineage#819
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Introduce an apps/ module that registers ui://dbt-mcp/<app> resources. On read, the server fetches a self-contained single-file HTML bundle from a configurable CDN (DBT_MCP_CDN_BASE) and serves it directly to MCP-app-capable hosts. - apps/register.py: register_app_resource() fetches and serves the app HTML - AppsConfig + DBT_MCP_CDN_BASE setting - register the get-lineage app resource on the dispatcher - update test mock + regenerate the published-app contract snapshot Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
MCP App UIs are built and released on a CDN, independently of this server, so their rendered content is intentionally out-of-contract. Skip content hashing for resources whose mime is text/html;profile=mcp-app and don't fetch them during snapshot generation. The contract still guards the resource's existence/shape (uri/name/mime/_meta) and the linked tool's input/output schema + _meta.resourceUri. Makes snapshot generation deterministic and network-free. Adds a test asserting mcp-app resource content is null and never fetched. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
…eage get_lineage now returns a LineageGraph (nodes + edges) as structured output and links the ui://dbt-mcp/get-lineage MCP app via _meta, so MCP-app hosts can render an interactive lineage graph. Edges are derived from each node's parentIds, filtered to the connected node set. Regenerate the contract snapshot (get_lineage output schema + meta) and add a transformation unit test. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Depth 5 traverses far enough downstream from well-connected nodes (e.g. a staging model) to return huge graphs (768 nodes / 1390 edges in one real case), overwhelming the lineage view. Depth 2 gives useful context without the blowup; callers can still pass a larger depth or 0 for the full graph. Regenerate the contract snapshot. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
Proof of concept for MCP Apps (tools with an interactive UI) in the dbt MCP server, with
get_lineagewired as the first one: it returns a structured lineage graph and links a UI resource that MCP-app-capable hosts (e.g. Claude Desktop) can render as an interactive DAG.What Changed
apps/module:register_app_resource()registers aui://dbt-mcp/<app>resource that, on read, fetches a self-contained single-file HTML bundle from a configurable CDN (DBT_MCP_CDN_BASE) and serves it directly to the host.get_lineagenow returns a structuredLineageGraph(nodes+edges) viastructured_output, and links its UI via_meta(ui.resourceUri). Edges are derived from each node's parents.depthlowered5 → 2(5 produced very large graphs for well-connected models).text/html;profile=mcp-appresources — the UI bundle is released independently on the CDN, so its bytes are out-of-contract; this keeps snapshot generation deterministic and offline. Snapshot regenerated.get_lineagetransformation and the contract behavior.Why
Lineage is far more useful as an interactive graph than as text/JSON. MCP Apps let the server hand a host an interactive UI inline, reusing the lineage data the server already produces, with the UI hosted on a CDN so it can evolve independently of the server release.
Related Issues
N/A (proof of concept).
Checklist
Additional Notes
This branch is a POC and intentionally not merge-ready. Before it can merge:
get-lineageresource registration — it currently registers unconditionally and points at a CDN path that 404s until the bundle is published; a release must not expose a dangling resource. Gate via config/env (e.g. only when the tool is enabled and/or the bundle is reachable).changie new).task check.DBT_MCP_CDN_BASEat it.