Switch diagram-model & audit-export calls to Accept-header content negotiation

[ericfitz]

Summary

The TMI server is replacing the ?format= query-parameter content-negotiation pattern with standard Accept-header content negotiation, and modernizing the media types. tmi-ux currently passes ?format= for the diagram-model fetch and the system-audit export; both must switch to setting the Accept request header.

This is a coordinated breaking change (no backwards compatibility); land it in sync with the server change on tmi dev/1.4.0.

Affected call sites

• src/app/pages/admin/audit/admin-audit.service.ts — exportSystem(filter, format) builds ?format=csv|ndjson. Switch to sending Accept: text/csv or Accept: application/x-ndjson (and drop format from the query params).
• src/app/pages/tm/services/tm-diagram-crud.service.ts / threat-model.service.ts — getDiagramModel(..., format: 'json'|'yaml'|'graphml') sends ?format=. Switch to Accept:
  • json → application/json (default)
  • yaml → application/yaml
  • graphml → application/graphml+xml

What to do

• Update exportSystem to set the Accept header instead of the format query param.
• Update getDiagramModel to map the requested representation to the Accept header (modern media types above).
• Regenerate src/app/generated/api-types.d.ts from the updated tmi-openapi.json (the format query param is gone).
• Update the related unit tests/specs (e.g. admin-audit.service.spec.ts, tm-diagram-crud.service.spec.ts, system-audit-view.component.spec.ts) to assert the Accept header rather than the format query param.
• Handle 406 Not Acceptable (now documented) for an unsupported Accept.

Notes

Media types modernized server-side: application/x-yaml → application/yaml (RFC 9512), application/xml → application/graphml+xml. The legacy synonym media types are no longer accepted — send the canonical types above. The server change lands on tmi dev/1.4.0; the OpenAPI spec is the source of truth.