MCP server page: exposure grid, preview as role/key, who can connect, modes, connect snippets (#523)

[nicdavidson]

Summary

The MCP service page now shows exactly what a server exposes and lets an admin preview it as any role or API key.

• Header: endpoint URL, health chip from mcp-health (link to the System page), reach chip (any logged-in user / N roles granted), Preview-as selector (Any admin, each role from mcp-access, each API key), summary tiles (tools advertised, ~tokens per turn, catalog mode + why, who can connect).
• Modes strip: Lazy (Auto/On/Off), Tool style (Merged/Prefixed; hidden for system_mcp), Writes (allow_writes), Authentication, Require role access. Each shows a one-line consequence that updates live from the local catalog model.
• What the client carries each turn: full-catalog vs 5-tool-facade bars against the 32 KB auto threshold, and the four lazy steps (greyed when the server is direct).
• Who can connect: rows from mcp-access joined with the real role rows and any bound API key (read/write level, reach across exposed APIs, requests/denied, Preview as, Edit access, Role page). Add existing role (server only unless APIs are ticked), Edit access (per exposed API None/Read/Read+write; table-limited grants link to the role page), Create role (optional API key shown once). Every save shows a plain diff first and states the change applies everywhere, not only through MCP. With require_role_access off: "Any logged-in user can connect" plus the roles seen in the last 30 days without a grant, each with Grant.
• Exposure grid: rows = attachable backends (Database: 16 verbs in Read/Spec/Procedures/Write; File: 6 verbs), row switch = exposed_services, cell = disabled_tools key (<sanitized>_<verb>, identical in both styles). Write verbs amber with a W badge. States: on, off, writes-off, denied (role lacks the verb), gone (hidden from this identity). Component-scoped grants show "limited to N tables" instead of marking every tool denied. Legend included. This replaces the synthesised Built-in Tools panels and the merged matrix from Feat/mcp merged tools UI #522; the custom tools editor is unchanged.
• Catalog panel: the previewed identity's tool chips (W on writes, facade chips distinct, custom tools dashed), counts, and a note on where the sizes come from.
• Connect card: Claude / Cursor / VS Code / ChatGPT / curl snippets that switch with the auth mode and the selected identity (key header when a key is previewed and key auth is on).
• Last 7 days: calls per exposed backend from mcp-usage (merged verbs land in an "All databases" row), zero calls highlighted.
• Create flow for a new mcp service: name -> attach APIs -> who can connect -> client settings -> review (this page in preview mode) -> connect snippet with a "waiting for the first call" state. New servers default to merged style and require role access on.
• Fixes on the way: the df-ai-mcp-servers create link now points at /ai/mcp/create; system_mcp never shows Tool style.

Screenshots were captured with Playwright against ng serve proxied to the dev instance (demo_mcp as admin, as orders_analyst_app, sysmcp, and the create-flow review step); the CLI cannot attach images to a PR body, so they are not embedded here.

Behaviour changes

Before: the MCP page listed tools for every active database/file service regardless of exposed_services (demo_mcp: 3 exposed, 10 shown), the health panel reported "No role grants access" although any authenticated user could connect, and there was no way to see what a role gets, who can connect, or what lazy/merged/key auth change.

After: the page shows only exposed backends; tool toggles map 1:1 to disabled_tools; new controls for require_role_access and allow_writes; role grants can be added, edited and created from the page (real role_service_access rows, diff shown first); the preview-as selector shows each role's/key's real catalog from mcp-catalog.

Upgrade impact: none on saved config. Existing disabled_tools keys are read as-is. When the backend lacks allow_writes / require_role_access the controls render disabled with a "needs a newer df-mcp-server" note; when mcp-catalog or mcp-health are missing the page falls back to tools/list calibration and says so. dist/ is rebuilt.

How verified: unit spec for the model (18 tests), npm run test:ci (22 suites / 187 tests), Playwright spec against the dev instance data through ng serve, manual screenshots of all four page states, npm run build.

Testing

• npm run lint: no errors in new or touched files (the two pre-existing label-has-associated-control errors in the custom-tools editor are unchanged from develop).
• npm run test:ci: 22 suites, 187 tests passing (adds src/app/adf-ai/mcp/mcp-model.spec.ts).
• PLAYWRIGHT_BASE_URL=http://localhost:4200 npx playwright test e2e/mcp-exposure.spec.ts with ng serve --proxy-config pointed at the dev instance: passes; asserts every grid row switch matches demo_mcp's exposed_services.
• npm run build succeeds; dist/ rebuilt in the final commit.

Closes #523