commit 7aea70c1f1c6c49f83a4537daedd6fee14ac0e3b
parent 38eaaf17c0bdaf264f26f08e5bbb9efb9149956c
Author: Jared Tobin <jared@jtobin.io>
Date: Sun, 25 Jan 2026 09:15:26 +0400
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+# ppad-bolt8
+
+Haskell implementation of BOLT #8 (Lightning Network encrypted transport).
+
+Specification: https://github.com/lightning/bolts/blob/master/08-transport.md
+
+## Project Structure
+
+- `lib/` - library source (Lightning.Protocol.BOLT8)
+- `test/` - tests (tasty + tasty-hunit)
+- `bench/` - benchmarks (criterion for timing, weigh for allocations)
+- `flake.nix` - nix flake for dependency and build management
+- `ppad-bolt8.cabal` - cabal package definition
+- `CLAUDE.md` / `AGENTS.md` - keep these in sync
+
+## Build and Test
+
+Enter devshell and use cabal:
+
+```
+nix develop
+cabal build
+cabal test
+cabal bench
+```
+
+Do not use stack. All dependency and build management via nix.
+
+## Dependencies
+
+### ppad libraries (use freely)
+
+Use ppad libraries (github.com/ppad-tech, git.ppad.tech) liberally.
+Current dependencies: ppad-aead, ppad-hkdf, ppad-secp256k1, ppad-sha256.
+
+### External libraries
+
+Use only minimal external dependencies. Prefer GHC's core/boot libraries
+(base, bytestring, primitive, etc.).
+
+**Ask for explicit confirmation before adding any library outside of:**
+- GHC boot/core libraries
+- ppad-* libraries
+- Test dependencies (tasty, QuickCheck, etc. for test-suite only)
+- Benchmark dependencies (criterion, weigh for benchmark only)
+
+## Code Style
+
+### Performance
+
+- Use strictness annotations (BangPatterns) liberally
+- Prefer UNPACK for strict record fields
+- Use MagicHash, UnboxedTuples, GHC.Exts for hot paths
+- Do not rely on UNBOX pragmas; implement primitives directly with
+ MagicHash and GHC.Exts when needed
+- Use INLINE pragmas for small functions
+- Refer to ppad-sha256 and ppad-fixed for low-level patterns
+
+### Type safety
+
+- Encode invariants into the type system
+- Use newtypes liberally (e.g., Sec, Pub, Session)
+- Use ADTs to make illegal states unrepresentable
+- Prefer smart constructors that validate inputs
+
+### Safety
+
+- Never use partial Prelude functions (head, tail, !!, etc.)
+- Use Maybe/Either for fallible operations
+- Validate all inputs at system boundaries
+
+### Formatting
+
+- Keep lines under 80 characters
+- Use Haskell2010
+- Module header with copyright, license, maintainer
+- OPTIONS_HADDOCK prune for public modules
+- Haddock examples for exported functions
+
+## Testing
+
+Use tasty to wrap all tests:
+- tasty-hunit for unit tests with known vectors
+- tasty-quickcheck for property-based tests
+- Source test vectors from specifications (RFC, BOLT spec, Wycheproof, etc.)
+
+Property tests should enforce invariants that can't be encoded in types.
+
+## Benchmarking
+
+Always maintain benchmark suites:
+- `bench/Main.hs` - criterion for wall-time benchmarks
+- `bench/Weight.hs` - weigh for allocation tracking
+
+Define NFData instances for types that need benchmarking.
+
+## Git Workflow
+
+- Feature branches for development; commit freely there
+- Logical, atomic commits on feature branches
+- Master should be mostly merge commits
+- Merge to master with `--no-ff` after validation
+- Always build and test before creating a merge commit
+- Write detailed merge commit messages summarising changes
+
+### Worktree flow (for planned work)
+
+When starting work on an implementation plan:
+
+```
+git worktree add ./impl-<desc> -b impl/<desc> master
+# work in that worktree
+# merge to master when complete
+git worktree remove ./impl-<desc>
+```
+
+### Commits
+
+- Higher-level descriptions in merge commits
+- Never update git config
+- Never use destructive git commands (push --force, hard reset) without
+ explicit request
+- Never skip hooks unless explicitly requested
+
+## Planning
+
+When planning work:
+- Highlight which steps can be done independently
+- Consider forking subagents for concurrent work on independent steps
+- Write implementation plans to `plans/IMPL<n>.md` if the project uses
+ this convention
+
+## Flake Structure
+
+The flake.nix follows ppad conventions:
+- Uses ppad-nixpkgs as base
+- Follows references to avoid duplication
+- Supports LLVM backend via cabal flag
+- Provides devShell with ghc, cabal, cc, llvm
