---

alwaysApply: true

description: Sentry Java SDK - Development Rules Overview

---

# Sentry Java SDK Development Rules

## Always Applied Rules

These rules are automatically included in every conversation:

- **coding.mdc**: General contributing guidelines, build commands, and workflow rules

## Domain-Specific Rules (Fetch Only When Needed)

Use the `fetch_rules` tool to include these rules when working on specific areas:

### Core SDK Functionality

- **`scopes`**: Use when working with:

- Hub/Scope management, forking, or lifecycle

- `Sentry.getCurrentScopes()`, `pushScope()`, `withScope()`

- `ScopeType` (GLOBAL, ISOLATION, CURRENT)

- Thread-local storage, scope bleeding issues

- Migration from Hub API (v7 → v8)

- **`deduplication`**: Use when working with:

- Duplicate event detection/prevention

- `DuplicateEventDetectionEventProcessor`

- `enableDeduplication` option

- **`offline`**: Use when working with:

- Caching, envelope storage/retrieval

- Network failure handling, retry logic

- `AsyncHttpTransport`, `EnvelopeCache`

- Rate limiting, cache rotation

- Android vs JVM caching differences

- **`feature_flags`**: Use when working with:

- Feature flag tracking and evaluation

- `addFeatureFlag()`, `getFeatureFlags()` methods

- `FeatureFlagBuffer`, `FeatureFlag` protocol

- `maxFeatureFlags` option and buffer management

- Feature flag merging across scope types

- Scope-based vs span-based feature flag APIs

### Integration & Infrastructure

- **`opentelemetry`**: Use when working with:

- OpenTelemetry modules (`sentry-opentelemetry-*`)

- Agent vs agentless configurations

- Span processing, sampling, context propagation

- `OtelSpanFactory`, `SentrySpanExporter`

- Tracing, distributed tracing

- **`new_module`**: Use when adding a new integration or sample module

### Testing

- **`e2e_tests`**: Use when working with:

- System tests, sample applications

- `system-test-runner.py`, mock Sentry server

- End-to-end test infrastructure

- CI system test workflows

## Usage Guidelines

1. **Start minimal**: Only include `coding.mdc` (auto-applied) for general tasks

2. **Fetch on-demand**: Use `fetch_rules ["rule_name"]` when you identify specific domain work

3. **Multiple rules**: Fetch multiple rules if task spans domains (e.g., `["scopes", "opentelemetry"]` for tracing scope issues)

4. **Context clues**: Look for these keywords in requests to determine relevant rules:

- Scope/Hub/forking → `scopes`

- Duplicate/dedup → `deduplication`

- OpenTelemetry/tracing/spans → `opentelemetry`

- new module/integration/sample → `new_module`

- Cache/offline/network → `offline`

- System test/e2e/sample → `e2e_tests`

- Feature flag/addFeatureFlag/flag evaluation → `feature_flags`