Document core-model decisions in CLAUDE.md and ARCHITECTURE

Records the landed data model and backend layout, the Phase 0 tree-scoping of Place (vs. the eventual shared gazetteer), and the temporary X-User-Id auth shim.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Justin Paul <justin@jpaul.me>

docs/ARCHITECTURE.md

@@ -93,7 +93,7 @@ Core entities and the important relationships. (Illustrative, not final DDL.)
 - **Person** — belongs to a Tree. Has many **Name** records (with parts: given, surname, prefix/suffix, and a type such as birth/married/alias) to support variants and changes over time. Carries living/deceased status.
 - **Relationship** — typed edge between two Persons within a Tree: parent–child (with a qualifier: biological, adoptive, step, foster, donor, guardian), partnership/marriage (with its own events), sibling (often derived). Modeling parentage as qualified edges — rather than assuming a two-biological-parent nuclear family — is what makes adoption, donor conception, and blended families first-class rather than awkward.
 - **Event** — typed (birth, death, marriage, residence, immigration, etc.), with a date (supporting ranges, approximations, and non-Gregorian calendars), an optional Place, and attachable to a Person or a partnership.
-- **Place** — a tenant-shared gazetteer entity: hierarchical (place within place), with **historical name variants and date ranges** so a record entered as "Königsberg, 1900" sorts and displays correctly against "Kaliningrad." Optional coordinates.
+- **Place** — a tenant-shared gazetteer entity: hierarchical (place within place), with **historical name variants and date ranges** so a record entered as "Königsberg, 1900" sorts and displays correctly against "Kaliningrad." Optional coordinates. *(Phase 0 scopes Place to a Tree via `tree_id` for absolute tenant isolation; a deployment-wide shared gazetteer is a deliberate later refinement. Variants live in a `PlaceName` child table.)*
 
 ### Sources (first-class)
 - **Source** — a reusable record of an origin: title, repository, type, optional URL, free citation text, optional quality grade. One Source backs many facts.
@@ -147,6 +147,7 @@ Three parts, deliberately separated:
 - `AuthProvider` interface with implementations for **local** (password + email verification/reset), **OIDC** (validated against Authentik; expected to work with Keycloak, Auth0, etc.), and **social** (Google, Apple, Facebook).
 - Operators enable any subset via config. This deployment will use Authentik (`auth.jpaul.io`) plus selected social providers; a bare self-hoster can run local-only.
 - Sessions are backend-issued; the assistant principal is minted per-session and scoped to the acting user.
+- *Phase 0 interim:* until the auth slice lands, the API identifies the caller via a temporary `X-User-Id` header shim (replaced by real sessions/tokens), and account creation is an open dev bootstrap. Every write still records an attributable actor in the audit log.
 
 ## 10. Search
 
@@ -178,7 +179,7 @@ Jobs are idempotent and retryable; an external failure degrades gracefully rathe
 **Repository layout (as scaffolded):**
 
 ```
-/backend           # FastAPI service, uv-managed (app/ = api, core; service/repository/domain land with the data model)
+/backend           # FastAPI, uv-managed. app/{api/v1, services (+privacy), repositories, models, schemas, core}; migrations/ = Alembic
 /deploy            # docker-compose.yml, Caddyfile, .env.example
 /.gitea/workflows  # Gitea Actions: build images → Gitea registry
 /frontend          # Next.js (pending)