A

Slice 110 - Viewer Service Boundaries

Intent#

Keep the local serve product behavior unchanged while making the viewer service easier to extend. serve already has the agreed multi-wiki scope: default viewer responses expose available registered local wikis, and serve --wiki narrows the viewer to one wiki. The current pressure is that services/viewer/service.py owns workspace fallback, registry filtering, page/topic/source DTO conversion, related-page lookup, and route use-case orchestration in one file.

Cosmic Python frames the adapter/service split as: "The Flask API now does only two things: it initializes a unit of work, and it invokes a service." In this repo, the server already invokes ViewerService; this slice keeps that edge thin and makes ViewerService delegate its own non-use-case collaborators instead of accumulating mapping and selection mechanics.

Read before coding:

  • MANUAL.md
  • docs/python-port-live-agreement.md
  • docs/reference/cosmic-python/chapter_06_uow.md

Scope#

  • Add a viewer workspace-scope collaborator for selected wiki fallback, registry availability filtering, and overview workspace ordering.
  • Add viewer projection helpers for converting index/workspace models into browser payload models.
  • Keep ViewerService as the service-facing use-case facade.
  • Add an architecture test that prevents workspace-selection and DTO mapping from regrowing inside service.py.

Out Of Scope#

  • No UI changes.
  • No new server routes.
  • No change to selected-wiki semantics.
  • No React/Next/Vite build step.
  • No source-code preview in the viewer.

Verification#

  • Focused viewer and server tests.
  • Focused architecture test.
  • Focused lint over viewer/server/tests.
  • Live serve API dogfood against two registered temp wikis.
  • Full pytest, ruff, and diff check before commit.