Add CLAUDE.md for Claude Code guidance

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+Rollbar Apple SDK monorepo: Objective-C & Swift SDK for crash reporting, error logging, and deployment tracking across all Apple platforms (macOS 10.13+, iOS 11+, tvOS 11+, watchOS 4+).
+
+## Build Commands
+
+Each module has its own `Package.swift` for standalone builds, plus a root `Package.swift` for the full SDK.
+
+```bash
+# Build the entire SDK
+swift build
+
+# Build a single module (from its subdirectory)
+cd RollbarCommon && swift build
+cd RollbarNotifier && swift build
+cd RollbarDeploys && swift build
+cd RollbarAUL && swift build
+```
+
+## Testing
+
+Tests run through the Xcode workspace, not `swift test`, because test targets are defined per-module and some require Xcode-specific infrastructure.
+
+```bash
+# Test a single module (e.g., RollbarCommon)
+xcodebuild \
+  -workspace RollbarSDK.xcworkspace \
+  -scheme RollbarCommon \
+  -derivedDataPath DerivedData \
+  -enableCodeCoverage YES \
+  build test \
+  CODE_SIGN_IDENTITY="-" \
+  CODE_SIGNING_REQUIRED=NO
+
+# Test RollbarNotifier (includes RollbarCrash, RollbarReport)
+xcodebuild \
+  -workspace RollbarSDK.xcworkspace \
+  -scheme RollbarNotifier \
+  -derivedDataPath DerivedData \
+  -enableCodeCoverage YES \
+  build test \
+  CODE_SIGN_IDENTITY="-" \
+  CODE_SIGNING_REQUIRED=NO
+```
+
+Replace `-scheme RollbarCommon` with `RollbarNotifier`, `RollbarDeploys`, or `RollbarAUL` to test other modules.
+
+For RollbarNotifier specifically, you can also run report-level tests via SPM:
+
+```bash
+cd RollbarNotifier && swift test --filter RollbarReportTests
+```
+
+## Module Architecture
+
+```
+RollbarCommon           (base module: DTOs, utilities, design patterns)
+    |
+    +-- RollbarNotifier (depends on RollbarCommon + RollbarCrash + RollbarReport)
+    |     |
+    |     +-- RollbarCrash   (C/C++/ObjC low-level crash monitors: signals, Mach, NSException, C++ exceptions, deadlock, zombie)
+    |     +-- RollbarReport  (Swift crash report formatting/parsing)
+    |
+    +-- RollbarDeploys  (depends on RollbarCommon; deployment tracking)
+    |
+    +-- RollbarAUL      (depends on RollbarCommon + RollbarNotifier; Apple Unified Logging)
+    |
+    +-- RollbarCocoaLumberjack (depends on RollbarCommon + RollbarNotifier + CocoaLumberjack)
+
+UnitTesting             (shared XCTest utilities, used by test targets)
+```
+
+## Key Conventions
+
+- **Language mix:** Primarily Objective-C with Swift used in RollbarReport and newer code. RollbarCrash is C/C++.
+- **DTO pattern:** Configuration and data structures use `RollbarDTO` base class hierarchy extensively. Internal access uses `RollbarDTO+Protected.h`.
+- **Public headers:** Exposed via `include/` directories with `module.modulemap` files for clean module boundaries.
+- **ObjC categories:** Follow `NS*+Rollbar` naming (e.g., `NSDate+Rollbar`, `NSDictionary+Rollbar`).
+- **Test targets:** Each module has both Swift (`*Tests`) and Objective-C (`*Tests-ObjC`) test targets.
+- **C++ standard:** C++17 with exception handling enabled (RollbarCrash).
+- **Swift version:** 5 (tools-version 5.7.1).
+
+## Distribution
+
+The SDK ships via SwiftPM, CocoaPods (8 podspec files at repo root), and Carthage. Version is synchronized across all podspecs and `Package.swift`. Current version: 3.3.3.
+
+## External Dependency
+
+The only external dependency is CocoaLumberjack (>= 3.8.0), used only by the RollbarCocoaLumberjack module.