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+# Copilot Instructions for stacks-core
+
+## Project Overview
+**stacks-core** is a Rust-based blockchain implementation for the Stacks protocol, supporting smart contracts, consensus, and node operations. This is blockchain software where **there is no roll-back** from bad deployments, requiring extremely high rigor in development.
+
+### Major Components
+- `clarity/`: Smart contract VM and Clarity language implementation
+- `stacks-node/`: Node runtime, networking, consensus logic
+- `stackslib/`: Core blockchain logic, chainstate, and transaction processing
+- `stacks-common/`, `clarity-types/`: Shared types and utilities across the codebase
+- `libsigner/`: Signer implementation for the Stacks blockchain
+- `libstackerdb/`: StackerDB database implementation
+- `pox-locking/`: Proof of Transfer (PoX) consensus logic
+- `stacks-signer/`: Signer binary for the Stacks blockchain
+- `contrib/`: Test suites, boot contracts, tools, and integration helpers
+- `docs/`: Developer and protocol documentation
+
+### Workspace Structure
+This is a Cargo workspace with 13 main crates (see `Cargo.toml`). Dependency versions are coordinated via `[workspace.dependencies]`.
+
+## Build & Development
+
+### Build Commands
+```bash
+# Full optimized release build
+cargo build --release
+
+# Faster build for low-RAM environments (16GB or less)
+cargo build --profile release-lite
+
+# Build specific packages
+cargo build --release --package stacks-node
+cargo build --release --package stacks-signer
+
+# Build with native CPU optimizations (edit .cargo/config.toml)
+RUSTFLAGS="-Ctarget-cpu=native" cargo build --release
+```
+
+### Testing
+```bash
+# Run all unit tests in parallel (recommended, uses nextest)
+cargo nextest run
+
+# Run workspace tests with standard cargo
+cargo test --workspace
+
+# Run specific test (single-threaded if needed)
+cargo test testnet -- --test-threads=1
+
+# Run tests with tags (using pinny-rs)
+cargo test -- --tag slow
+cargo nextest run --tags 'slow & bitcoind'
+```
+
+**Test Tagging**: Integration tests must be tagged using [pinny-rs](https://github.com/BitcoinL2-Labs/pinny-rs/):
+- `slow`: Tests running over a minute
+- `bitcoind`: Tests requiring Bitcoin daemon
+- `flaky`: Tests with flaky behavior
+
+Tests taking >1 minute or requiring `--test-threads 1` should be marked `#[ignore]`.
+
+### Code Quality
+
+**Formatting (REQUIRED)**:
+```bash
+# Check formatting (required for PR approval)
+cargo fmt-stacks --check
+
+# Auto-format code
+cargo fmt-stacks
+```
+
+**Linting (REQUIRED)**:
+```bash
+# Check clippy warnings (required for PR approval)
+cargo clippy-stacks
+cargo clippy-stackslib
+```
+
+Both commands must pass with zero warnings before opening a PR.
+
+### Contract Testing
+```bash
+# Test Clarity contracts with Clarinet
+cd contrib/boot-contracts-unit-tests && clarinet test
+cd contrib/core-contract-tests && clarinet test
+```
+
+## Architecture & Patterns
+
+### Consensus-Critical Code
+**CRITICAL**: Changes affecting block/transaction processing or state root hashes are consensus-breaking:
+- Must be opened against `next` branch (never `develop` or `master`)
+- Must be gated on Stacks epoch activation
+- Requires a SIP (Stacks Improvement Proposal)
+- Examples: changing wire formats, MARF storage, Clarity functions/costs, transaction validation
+
+### Database Changes
+- **Preserve schema when possible** - users shouldn't need to re-sync from genesis
+- Schema changes require:
+  - New schema version
+  - Migration logic with test coverage
+  - Indexed columns for all queries (no table scans - use `BLOCKSTACK_DB_TRACE` to verify)
+- If no migration possible, verify genesis sync before submitting PR
+- Database changes cannot be consensus-critical unless part of hard fork
+
+### Code Organization
+- **Business logic and I/O must be separated**: Use inner/outer function pattern
+  - Inner functions: pure logic, no I/O
+  - Outer functions: handle I/O, call inner functions
+- **One subsystem per file** (except `mod.rs`)
+- Directories represent collections of related subsystems
+
+### Data Input Rules
+- **Network/Bitcoin/config data is UNTRUSTED** - handle any byte sequence safely
+- **Database data is TRUSTED** - can panic if corrupted
+- All input processing must be:
+  - Space-bound (maximum size limits)
+  - Resource-bound (RAM/CPU limits for deserialization)
+  - Time-bound (for network inputs)
+- **Never panic on untrusted data** - use proper error handling
+
+### Error Handling & Logging
+- Use `Result` with proper `Error` types (define new types for new modules)
+- Never use `println!()` or `eprintln!()` - use logging macros: `trace!()`, `debug!()`, `info!()`, `warn!()`, `error!()`
+- Use structured logging: `info!("Block appended"; "block_id" => %block_id)`
+- `test_debug!()` and `trace!()` only run in tests
+- `debug!()` enabled via `BLOCKSTACK_DEBUG` env var
+
+## Branching & Release
+
+### Branch Strategy (Gitflow)
+- `master`: Production-ready state
+- `develop`: Latest development changes for next release
+- `next`: Consensus-breaking changes for future hard forks
+- `release/X.Y.Z.A.n`: Release branches
+- Feature branches: `feat/`, `fix/`, `chore/`, `docs/`, `ci/`, `test/`, `refactor/`
+
+### Versioning
+Format: `X.Y.Z.A.n` (from `versions.toml`)
+- X: Major version (e.g., Stacks 3.0)
+- Y: Consensus-breaking changes
+- Z: Non-consensus breaking, requires fresh chainstate
+- A: Non-consensus breaking, new features
+- n: Patches and hotfixes
+
+### Release Process
+- Avoid releases during PoX prepare phase (24h before cycle start)
+- Block validation required before release
+- CHANGELOG update required
+- Release candidates tested on staging infrastructure
+- See `docs/release-process.md` for full process
+
+## PR Requirements
+
+### Submission Checklist
+- Answer: What problem? What solution? Why best solution? What alternatives?
+- Reviewable in ≤2 hours (break into smaller PRs if needed)
+- Pass `cargo fmt-stacks --check` and `cargo clippy-stacks`
+- Include test coverage (unit + integration if consumer-visible)
+- Update CHANGELOG for user-facing changes
+- Update OpenAPI spec (`docs/rpc/openapi.yaml`) for RPC changes
+- Document all public APIs with rustdoc comments
+- Performance claims need reproducible benchmarks
+
+### Documentation Standards
+- Each file needs copyright statement
+- Non-test modules need module-level documentation
+- Public functions/structs/enums/traits need rustdoc comments
+- Private non-trivial functions need comments
+- Struct/enum fields need comment strings
+- Don't restate names in comments - add new information only
+
+### Code Conventions
+- Simplicity over cleverness - reject complex implementations
+- Stable Rust only (no nightly features)
+- Minimal dependencies (case-by-case approval)
+- Minimal `unsafe` code
+- No compiler warnings (no warning-masking macros)
+
+## Integration Points
+
+### External Dependencies
+- **Clarinet**: Contract testing framework (`contrib/*/Clarinet.toml`)
+- **Docker**: Container builds (`Dockerfile`, `deployment/`)
+- **nextest**: Parallel test runner (recommended)
+- **pinny-rs**: Test tagging system
+- **Bitcoin**: Burnchain integration (requires bitcoind for some tests)
+
+### Cross-Component Communication
+- Node → VM: `stacks-node` invokes `clarity` for contract execution
+- Shared types: `stacks-common/` and `clarity-types/` provide cross-crate interfaces
+- PoX: `pox-locking/` implements consensus, used by `stacks-node/`
+- Signer: `libsigner/` provides signing interfaces
+
+### Configuration Files
+- `versions.toml`: Version numbers for releases
+- `.cargo/config.toml`: Cargo aliases and build settings
+- `Cargo.toml`: Workspace configuration and dependencies
+- `contrib/*/Clarinet.toml`: Contract project configurations
+
+## Important Policies
+
+### AI Code Generation
+**STRICTLY PROHIBITED**: The Stacks Foundation does not accept AI-generated code PRs due to licensing concerns. All code must be human-written.
+
+### Review Expectations
+- Reviews should complete in 2 business days
+- Reviewers provide complete acceptance plan in one round
+- Submitters incorporate clarifications into code comments
+- Large refactorings must be in separate PRs
+
+## Common Tasks
+
+### Run the Node
+```bash
+# Start testnet follower
+cargo stacks-node -- start --config ./sample/conf/testnet-follower-conf.toml
+
+# Or with release build
+./target/release/stacks-node start --config ./sample/conf/testnet-follower-conf.toml
+```
+
+### Performance Testing
+- Use profiling tools (see `docs/profiling.md`)
+- Provide reproducible benchmarks for performance improvement PRs
+- Example: [PR #3075](https://github.com/stacks-network/stacks-core/pull/3075)
+
+### Debugging
+- Rust tools: `rust-gdb`, VS Code Rust extension
+- Enable debug logs: `BLOCKSTACK_DEBUG=1`
+- Database query tracing: `BLOCKSTACK_DB_TRACE=1`
+- Check verbose node logs in `stacks-node/src/`
+
+## Key Documentation
+- `CONTRIBUTING.md`: Full contribution guidelines
+- `docs/release-process.md`: Release procedures
+- `docs/branching.md`: Git branching strategy
+- `docs/ci-workflow.md`: CI/CD pipeline
+- `docs/profiling.md`: Performance analysis
+- `docs/rpc-endpoints.md`: RPC API documentation
+- `docs/event-dispatcher.md`: Event system
+- `docs/mining.md`: Mining documentation
+
+## File Locations
+- Main crates: `clarity/`, `stacks-node/`, `stackslib/`, `stacks-common/`, `clarity-types/`
+- Supporting crates: `libsigner/`, `libstackerdb/`, `pox-locking/`, `stacks-signer/`
+- Tests: `*/src/tests/`, `contrib/*/tests/`
+- Fuzz targets: `clarity/fuzz/`, `stackslib/fuzz/`
+- Docs: `docs/`, `README.md`, `CONTRIBUTING.md`
+- CI: `.github/workflows/`
+
+---
+
+_These instructions prioritize safety, correctness, and maintainability for blockchain software. When in doubt, ask for clarification._