Add independent MCP PDF report delivery

README.md

@@ -118,14 +118,15 @@ Authentication is implemented with `Flask-HTTPAuth`. The current code checks `BE
 
 ## MCP PoC
 
-`mcp_server.py` provides a local stdio-only Model Context Protocol server. It is
+`mcp_server.py` provides a Model Context Protocol server. It is
 a thin adapter over the same domain services used by Flask: article lookup,
 direct roll calculation, product-length calculation, material-weight calculation,
 transport analysis, and configured production-machine feasibility.
 The available PoC tools are `get_article`, `search_articles`,
 `calculate_material_weight`, `calculate_product_length`,
 `calculate_roll_diameter`, `analyze_transport_capacity`, `get_machine`,
-`check_production_feasibility`, and `calculate_machine_max_product_length`.
+`check_production_feasibility`, `calculate_machine_max_product_length`, and
+`generate_calculation_pdf`.
 
 Install the pinned dependencies, including `mcp==1.26.0`, in the existing
 environment, then start it with:
@@ -135,8 +136,16 @@ environment, then start it with:
 .venv/bin/python mcp_server.py
 ```
 
-The PoC has no MCP resources, HTTP/SSE transport, remote authentication, or
-dedicated target-length calculation tool or extrapolation support.
+The server supports the existing `stdio` transport (the default) and
+`streamable-http`. MCP PDF delivery requires `streamable-http`; it has no
+dependency on the Flask web application. Native MCP resources are intentionally
+not used because the installed MCPO 0.0.20 does not preserve resource links or
+embedded resources. The PoC has no remote authentication or dedicated
+target-length calculation tool or extrapolation support.
+
+In `stdio` mode, `generate_calculation_pdf` returns a structured
+`artifact_delivery_unavailable` response rather than creating an unreachable
+report. Existing calculation tools work in either transport.
 
 Tool calling semantics:
 
@@ -173,6 +182,37 @@ Tool calling semantics:
   use `calculate_material_weight` when the core is unknown and only material
   weight is needed. On success, it returns `transport_roll_inputs`, the
   browser-equivalent transport bundle.
+- `generate_calculation_pdf` is strictly opt-in: call it only after the user
+  explicitly asks for a PDF or calculation report. Supply the original inputs
+  from `calculate_roll_diameter`, never calculated diameters, weights, warnings,
+  or notes. It recalculates through the same RollCalc domain service and uses
+  the existing one-page renderer. Ordinary calculation calls neither generate
+  nor suggest a PDF.
+
+For example, calculate a roll normally with `calculate_roll_diameter`. If the
+user later asks “Mach mir daraus ein PDF”, call `generate_calculation_pdf` with
+the original calculation inputs. Its successful response contains a safe
+`filename`, expiry metadata, and a browser-ready `download_url`; MCPO/OpenWebUI
+can present that URL as a download link. PDFs exist only in the MCP host's local
+temporary store, not in Flask or shared storage. Each URL has a 256-bit opaque
+capability token and expires after 24 hours during report-store access; whoever
+possesses the URL can download the report until expiry. The user’s browser must
+be able to reach the MCP-host public origin over HTTPS.
+
+For independent PDF delivery, configure and run the MCP host as follows:
+
+```bash
+export ROLLCALC_MCP_TRANSPORT=streamable-http
+export ROLLCALC_MCP_HOST=0.0.0.0
+export ROLLCALC_MCP_PORT=8000
+export ROLLCALC_MCP_ARTIFACT_PUBLIC_BASE_URL=https://rollcalc-mcp.example.internal
+.venv/bin/python mcp_server.py
+```
+
+`ROLLCALC_MCP_ARTIFACT_PUBLIC_BASE_URL` is the externally browser-reachable
+origin for this MCP service, not the Flask website URL. MCPO connects to the
+MCP host with `--server-type streamable-http -- https://<mcp-host>/mcp`; the
+browser follows the returned `/reports/<capability>.pdf` URL directly.
 - `analyze_transport_capacity` uses roll/core diameters in mm; roll width and
   transport dimensions in m; and roll/payload weights in kg.
   `product_length_m` is the material length represented by one roll, used only