docs: remove TDD focus, emphasize DRY and YAGNI (#55)

AGENTS.md

@@ -31,9 +31,13 @@ Hooks live in `.husky/` and auto-install on any plain `npm install` via the `pre
 
 Follow PSR-4 and Laravel conventions: PascalCase classes, camelCase methods, and snake_case database columns. Use four spaces (two in YAML, except four in Compose files), LF endings, and UTF-8 as defined by `.editorconfig`. Every project-owned PHP file must place `declare(strict_types=1);` immediately after `<?php`. Keep domain code independent of Filament and Livewire. Run `composer pint` to format and `composer phpstan` before review.
 
+## Design Principles: DRY & YAGNI
+
+Write for the problem at hand, not an imagined future. **DRY**: extract and reuse a piece of logic as soon as it is genuinely duplicated in more than one place — but not before. **YAGNI**: do not add abstraction, configurability, or layers speculatively; add them only when a concrete requirement demands it. Prefer the simplest thing that solves the current requirement. Duplication that appears once is not yet a reason to abstract — wait for a second real occurrence before generalizing. This repo already encodes YAGNI in `openspec/config.yaml` (no generic repositories / `BaseService`); keep that spirit in new code. Avoid over-engineering and avoid premature extraction.
+
 ## Testing Guidelines
 
-Tests use Pest 4; browser coverage uses Pest Browser/Playwright. Name files by behavior, ending in `Test.php`, and add tests in the suite matching the changed layer. Feature tests use `RefreshDatabase`. Add architecture coverage for dependency-boundary changes. No numeric coverage threshold is enforced, but changed behavior must have regression coverage.
+Tests use Pest 4; browser coverage uses Pest Browser/Playwright. Tests are verification, not a design driver — write them to cover behavior you've already implemented, matching the layer you changed. Name files by behavior, ending in `Test.php`, and add tests in the suite matching the changed layer. Feature tests use `RefreshDatabase`. Add architecture coverage for dependency-boundary changes. No numeric coverage threshold is enforced; add regression tests where a bug was fixed or behavior is non-obvious, without making tests a front-loaded design ceremony.
 
 ## Commit & Pull Request Guidelines
 

CLAUDE.md

@@ -14,6 +14,10 @@ If the import above did not load, read `AGENTS.md` at the repo root now — it i
 - Every project-owned PHP file starts with `declare(strict_types=1);` immediately after `<?php`.
 - Browser tests are CI-only (they run against a FrankenPHP container built by `docker build`, not `artisan serve`).
 
+## Design principles: DRY & YAGNI (not TDD)
+
+Write for the problem at hand, not an imagined future. **DRY**: extract and reuse only once logic is genuinely duplicated in more than one place. **YAGNI**: no speculative abstraction, configurability, or layers — add them only when a concrete requirement demands it. Prefer the simplest thing that solves the current requirement; avoid over-engineering and premature extraction. Tests are verification, not a design driver: write them to cover behavior already implemented, not as a front-loaded TDD ceremony.
+
 ## Environment note
 
 PHP and Composer are **not on PATH** in this environment, and `vendor/` and `node_modules/` are absent. Every `composer …` / `php artisan …` command in `AGENTS.md` and `README.md` assumes a PHP 8.4+ runtime with Composer 2 installed. Verify the toolchain before promising a command ran.