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CLAUDE.md

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+# CLAUDE.md
+
+Guidance for Claude Code when working in this repository.
+
+## What this is
+
+`symplify/phpstan-rules` — a set of 80+ PHPStan rules (clean architecture, naming,
+visibility, and Symfony/Doctrine/PHPUnit proven practices). It is a PHPStan extension
+(`"type": "phpstan-extension"` in `composer.json`), PHP `>=8.3`, PHPStan `^2.1`.
+
+## Layout
+
+- `src/Rules/` — the rules, grouped by topic (`Complexity/`, `Doctrine/`, `Symfony/`,
+  `PHPUnit/`, `Explicit/`, `Domain/`, `Enum/`, `Convention/`, `Rector/`, …).
+- `src/Collector/` — PHPStan collectors (e.g. `NewWithFollowingSettersCollector`).
+- `src/Enum/RuleIdentifier.php` (+ `RuleIdentifier/`) — string rule identifiers used by
+  every rule, e.g. `symplify.noTestMocks`.
+- `config/*.neon` — one set per topic. Sets registered globally via the
+  `composer.json` `extra.phpstan.includes` are auto-loaded by
+  `phpstan/extension-installer`; the rest are opt-in via `includes:` in the user's
+  `phpstan.neon`.
+- `tests/Rules/<RuleName>/` — one dir per rule, with `Fixture/` PHP files and a
+  `config/configured_rule.neon`.
+
+## Opt-in parameters
+
+Two rule groups are disabled by default and toggled by a single parameter:
+
+- `mocks: true` — enables the PHPUnit mock rules in `config/mock-rules.neon`
+  (registered via `conditionalTags` keyed on `%mocks%`).
+- `ctor: true` — enables `NewOverSettersRule` + its collector in
+  `config/ctor-rules.neon` (passed as `isEnabled: %ctor%` arguments).
+
+Both `config/ctor-rules.neon` and `config/mock-rules.neon` are listed in
+`composer.json` `extra.phpstan.includes`, so they load automatically but stay inert
+until the parameter is set to `true`.
+
+## Adding a rule
+
+1. Create the rule in the matching `src/Rules/<Topic>/` dir; add its identifier to
+   `src/Enum/RuleIdentifier.php`.
+2. Register it in the matching `config/<topic>-rules.neon`.
+3. Add a test dir under `tests/Rules/<RuleName>/` with `Fixture/` files and a
+   `config/configured_rule.neon`. Tests extend PHPStan's `RuleTestCase`, use
+   `#[DataProvider('provideData')]`, assert `[ERROR_MESSAGE, $line]` pairs, and wire
+   the rule via `getAdditionalConfigFiles()` + `getByType()`. Match the tone of the
+   existing tests.
+4. Document the rule in `README.md` under the right section.
+
+## Before finishing — always run
+
+```bash
+composer fix-cs    # ECS auto-fix
+composer rector    # Rector dry-run (drop --dry-run to apply)
+composer phpstan    # static analysis
+vendor/bin/phpunit  # tests
+```
+
+Fix anything they report. Cover new services/rules with a unit test; do not test value
+objects or entities.