Rewrite project documentation

AGENTS.md

@@ -2,12 +2,33 @@
 
 ## Project Goal
 
-Build a spreadsheet-like electrical distribution board circuit list editor.
+Maintain and extend a spreadsheet-like electrical distribution board circuit list editor.
 
 The editor is used for electrical planning in execution design.
 
 It must support circuits, device rows, project devices, drag-and-drop restructuring, stable equipment identifiers and later electrical sizing logic.
 
+## Current Supported Architecture
+
+- Frontend: Next.js App Router under `src/app` with reusable editor modules under `src/frontend`.
+- API: Express composition starts in `src/server/index.ts`.
+- Domain rules: `src/domain`.
+- Persistence: SQLite/Drizzle schemas, repositories and migrations under `src/db`.
+- Primary editor route:
+  `src/app/projects/[projectId]/circuit-lists/[circuitListId]/tree-edit/page.tsx`.
+- Primary editor component: `src/frontend/components/circuit-tree-editor.tsx`.
+- Grid ownership, projection, insertion and safety rules live in the pure
+  `src/frontend/components/circuit-grid-*.ts` modules.
+- Critical multi-write commands use injected transaction repositories with real
+  SQLite commit/rollback tests.
+
+The supported runtime model is Circuit-First. The former Consumer UI and API are
+removed. Retained `consumers` rows, migration mappings and reports are upgrade-only
+data accessed by `npm run db:migrate:legacy-consumers`; do not build application
+features on them.
+
+See `docs/current-architecture.md` for the complete module and request flow.
+
 ## Critical Domain Rules
 
 - A circuit is not the same thing as one device row.
@@ -112,6 +133,9 @@ Renumber only when the user explicitly triggers "Renumber section".
 
 The circuit list table should behave like a spreadsheet.
 
+User-facing frontend text must be German unless a domain-standard technical term
+is intentionally retained.
+
 Cells show static text by default.
 
 Inline edit starts by:
@@ -196,7 +220,8 @@ After saving, the row becomes linked to the new project device.
 
 ## Undo / Redo
 
-Implement undo/redo for structural and destructive operations.
+Session-local undo/redo exists for structural and destructive operations.
+Persistent project-wide undo/redo remains future work.
 
 Required operations:
 
@@ -232,6 +257,46 @@ Future sizing will need:
 
 Users must be able to override sizing suggestions.
 
+## Persistence and Migration Rules
+
+- SQLite is the currently supported database.
+- Never edit an already applied migration.
+- Back up an existing database before applying a new migration.
+- Inspect generated SQL; it must contain only the intended schema change.
+- Keep database backups separate from future logical project snapshots.
+- Do not import the global SQLite singleton into domain services.
+- Keep synchronous SQLite transaction behavior inside persistence adapters.
+- Preserve stable UUIDs and explicit transaction boundaries for a later
+  PostgreSQL adapter.
+
+## Current Deferred Work
+
+- persistent project revisions and undo/redo
+- named logical snapshots and restore
+- Revit/CSV/IFCGUID round-trip
+- full electrical sizing
+- multi-user/PostgreSQL operation
+- supported production deployment
+
+Do not implement these while working on an unrelated phase.
+
+## Documentation and Verification
+
+- `README.md` is the setup entry point.
+- `docs/README.md` is the documentation map.
+- `docs/current-architecture.md` describes current code paths.
+- `docs/spec/` contains requirements and roadmap, not proof of implementation.
+- `docs/archive/` is historical and must not drive current implementation.
+
+For a normal code change run the relevant focused tests plus:
+
+- `npm test`
+- `npm run build:api`
+- `npm run build:web`
+- `npx tsc --noEmit -p tsconfig.next.json`
+
+Use a concise imperative commit message for each completed, verified work package.
+
 ## Response Style for Codex
 
 Be concise.