BTrace is a Java diagnostic tool that dynamically inserts tracing into running Java applications without restarting or recompiling them. Java developers and operations teams use it to inspect methods, timings, fields, allocations, and other runtime behavior in production environments. Catalogue add-ons provide instructions for using BTrace.
Borrowing it
Nothing to install: this file belongs to btraceio/btrace. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/btraceio/btrace/develop/.github/copilot-instructions.mdgit clone --depth 1 https://github.com/btraceio/btraceWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/btraceio/btrace/copilot-instructions)<a href="https://agentmods.dev/instructions/btraceio/btrace/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/btraceio/btrace/copilot-instructions/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/btraceio/btrace/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/btraceio/btrace/copilot-instructions.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.01098 | $0.01098 |
| Opus 5.5 | $0.00439 | $0.00439 |
| Sonnet 5.5 | $0.00220 | $0.00220 |
| Haiku 4.5 | $0.00110 | $0.00110 |
Grade A, and why
btrace copilot-instructions.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 126 lines — stays where its author put it; the contents beside it link to each section on GitHub.
GitHub Copilot Instructions for BTrace
About BTrace
BTrace is a safe, dynamic tracing tool for the Java platform. It dynamically instruments running Java applications to inject tracing code at runtime using bytecode instrumentation.
Project Structure
- Gradle multi-module project with modules named
btrace-* - Core modules:
btrace-core,btrace-agent,btrace-runtime,btrace-client,btrace-instr - Build artifacts:
btrace-distfor distributions - Tests:
integration-tests/for integration tests,src/test/javain modules for unit tests - Documentation:
docs/directory
Architecture Overview
- btrace-agent: Attachable Java agent with class transformer, manages script lifecycle
- btrace-compiler: Verifies and compiles BTrace scripts to bytecode
- btrace-instr: ASM-based instrumentation and weaving utilities
- btrace-runtime: APIs for scripts (printing, timers, data collection)
- btrace-client: CLI/attach tooling for sending scripts to target JVM
- services: SPI for pluggable exporters (e.g., statsd)
Development Guidelines
Language & Versions
- Language: Java
- Source/Target: Java 8
- Build toolchain: JDK 11
- Test framework: JUnit Jupiter (JUnit 5)
Code Style
- Format: Google Java Format enforced via Spotless
- Packages: All under
io.btrace.* - Naming: Module names follow
btrace-<component>pattern - Imports: Order enforced; remove unused imports
- Comments: Only add if they match existing style or explain complex logic
Building & Testing
# Full build with unit tests
./gradlew build
# Build distribution only
./gradlew :btrace-dist:build
# Run unit tests
./gradlew test
# Run integration tests (requires dist build first)
./gradlew -Pintegration test
# Format code
./gradlew spotlessApply
# Check formatting
./gradlew spotlessCheck
Important Environment Variables
JAVA_HOME: Required for buildsTEST_JAVA_HOME: Required for integration tests (typically JDK 11)BTRACE_TEST_DEBUG=true: Enable verbose integration test outputBTRACE_HOME: Optional, points to exploded dist
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2mo ago First seen · 126 lines · 1,098 tokens per session scan A ec3b5fa1b3d5
btrace copilot-instructions.md is an instructions file published in the GitHub repository btraceio/btrace (5,997 stars, last pushed yesterday), licensed Apache-2.0. It adds 1,098 tokens to every session, about $0.0044 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other instructions, from other repositories
vibetags com-example-service-OrderService.instructions.md
Instructions for PIsberg/vibetags, covering copilot instructions for orderservice, rules for method calculatetax, rules for method processpayment, rules for method validateorder and context & focus.
vibetags com-example-security-SecurityConfig.instructions.md
Instructions for PIsberg/vibetags, covering copilot instructions for securityconfig, locked status, rules for method getencryptionalgorithm, rules for method getkeyrotationhours and rules for method getmaxloginattempts.
vibetags com-example-service-TransactionalPaymentService.instructions.md
Instructions for PIsberg/vibetags, covering copilot instructions for transactionalpaymentservice and strict exception handling.
vibetags com-example-concurrent-SessionCache.instructions.md
Instructions for PIsberg/vibetags, covering copilot instructions for sessioncache and thread-safety guarantee.
vibetags com-example-config-AsyncTestConfig.instructions.md
Instructions for PIsberg/vibetags, covering copilot instructions for asynctestconfig and immutable type.
vibetags com-example-gmm-platform-FeatureGate.md
Instructions for PIsberg/vibetags, covering amazon kiro steering: featuregate and feature flag gate.