feat(docs): add agent guide, build class patterns, log triage, and AI instructions

.github/skills/staticphp-package-maintenance/references/build-class-patterns.md

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+# StaticPHP Build Class Patterns
+
+## Contents
+
+- When a class is needed
+- Package attributes
+- Stage and hook behavior
+- Executor choices
+- Common patterns
+- Failure-safe edits
+
+## When a Class Is Needed
+
+Do not add a PHP package class for simple metadata. Use YAML alone when StaticPHP can infer the configure args, dependencies, and verification.
+
+Add or update a class when the package needs:
+
+- OS-specific build commands.
+- Custom validation before building.
+- Custom PHP configure arguments.
+- Patches or file edits before build.
+- Hooks into another package's stage.
+- Custom source/binary download or extraction logic.
+- Package info shown by dev tooling.
+
+Package classes live in `src/Package/*` and are discovered through PSR-4 plus attributes. Config must exist first; `PackageLoader` throws if an attribute references an undefined package.
+
+## Package Attributes
+
+Class-level package attributes:
+
+- `#[Extension('curl')]` maps to package `ext-curl` if the prefix is omitted.
+- `#[Library('openssl')]`
+- `#[Target('php')]`
+- `#[Tool('zig')]`
+
+Method-level attributes:
+
+- `#[BuildFor('Linux'|'Darwin'|'Windows')]`: registers the `build` stage for that OS.
+- `#[Stage('name')]`: registers a named stage; defaults to the method name when omitted.
+- `#[BeforeStage('package', 'stage', 'only-when-package-resolved')]`: hook before a target package stage.
+- `#[AfterStage('package', 'stage', 'only-when-package-resolved')]`: hook after a target package stage.
+- `#[PatchBeforeBuild]`: runs once before package build unless `.spc-patched` exists; return `true` to write that marker.
+- `#[CustomPhpConfigureArg('Linux')]`: supplies custom extension configure args.
+- `#[Validate]`: validates environment/source assumptions.
+- `#[Info]`: returns package information for tooling.
+- `#[InitPackage]`: runs while loading a package class.
+- `#[ResolveBuild]`: target package callback for resolving build dependencies.
+- `#[ConditionalOn(SomeClass::class)]`: conditionally enables before/after hooks only when DI has the class.
+
+## Stage and Hook Behavior
+
+`PackageBuilder::buildPackage()` does:
+
+1. Ensure build directories exist.
+2. Skip if already installed unless forced.
+3. Ensure source exists for non-virtual packages.
+4. Emit `PatchBeforeBuild` callbacks.
+5. Run the `build` stage.
+6. Install license data.
+7. Record tool package versions where relevant.
+
+`Package::runStage()` wraps a stage with:
+
+1. `BeforeStage` callbacks.
+2. The stage method itself.
+3. `AfterStage` callbacks.
+
+SPC exceptions bind package and stage metadata. Preserve that behavior by throwing existing `SPCException` subclasses instead of raw exceptions when adding new failure paths.
+
+## Executor Choices
+
+Use existing executors where possible:
+
+- `UnixAutoconfExecutor`: for Unix packages using `./configure && make && make install`. It injects default static flags and copies `config.log` into SPC logs on failure.
+- `UnixCMakeExecutor`: for Unix CMake packages. It writes toolchain settings and copies CMake configure/error/output logs on failure.
+- `WindowsCMakeExecutor`: for Windows CMake packages.
+- `shell()->cd(...)->initializeEnv($pkg)`: for custom Unix command chains.
+- `cmd()->cd(...)`: for Windows command chains.
+
+Prefer `FileSystem` helpers for file edits and copies so behavior stays consistent.
+
+## Common Patterns
+
+Minimal library class:
+
+```php
+#[Library('example')]
+class example
+{
+    #[BuildFor('Linux')]
+    public function build(LibraryPackage $pkg): void
+    {
+        (new UnixAutoconfExecutor($pkg))
+            ->configure()
+            ->make();
+    }
+}
+```
+
+Extension hook into PHP build:
+
+```php
+#[Extension('curl')]
+class curl
+{
+    #[BeforeStage('php', [php::class, 'makeForWindows'], 'ext-curl')]
+    public function patchBeforePhpBuild(): void
+    {
+        // Adjust env, generated build files, or linker flags.
+    }
+}
+```
+
+Validation:
+
+```php
+#[Validate]
+public function validate(): void
+{
+    if (SystemTarget::getTargetOS() === 'Windows' && WindowsUtil::findCommand('perl.exe') === null) {
+        throw new EnvironmentException('You need to install perl first!');
+    }
+}
+```
+
+Custom configure args should be used when YAML `arg-type` is `custom` or when args need package/install context:
+
+```php
+#[CustomPhpConfigureArg('Linux')]
+public function configureArg(PhpExtensionPackage $ext): string
+{
+    return '--with-example=' . $ext->getBuildRootPath();
+}
+```
+
+## Failure-Safe Edits
+
+- Make hooks conditional with the third `BeforeStage`/`AfterStage` argument when a dependency must be resolved before the hook should run.
+- Keep platform-specific code under matching `#[BuildFor]` methods rather than branching heavily inside one method.
+- If a patch changes upstream source, place patch files in `src/globals/patch/` and describe them with `#[PatchDescription]` where appropriate.
+- If a class only mutates environment variables for another package, search for existing hooks first to avoid duplicate linker flags.
+- After adding attributes, run registry/config tests because invalid stages and unknown packages are caught during loading.