Merge pull request #15 from moneydevkit/austin_add-agents-md

Add AGENTS.md

Author: amackillop

AGENTS.md

@@ -0,0 +1,57 @@
+## Project
+mdkd: An LSP client lightning node integrated with [MoneyDevKit](https://moneydevkit.com/)
+This project is released. Be careful about backwards compatibility.
+
+## Commands
+`just` lists all recipes. Use `just check` for quick validation (clippy, fmt, tests, nix)
+as you work. Use `just integration-tests` to run the slower integration tests when
+you are finished as a final check.
+
+## Planning
+- When planning a non-trivial change, you can use `git --no-pager log -n 3 -L <start>,<end>:<file>`
+for more context about a particular section of code. Commit messages can carry important context in
+this project so leverage that. Skip this for obvious fixes and additions.
+
+## Guidelines
+- **Pure core, thin effectful shell.** Separate logic from I/O and other side-effects. Build pure data structures that describe intent,
+  then interpret them in a thin layer that performs effects. Test the pure core; the effectful shell should be too simple to fail.
+- **Use integration tests to verify end-to-end behaviour** The unit tests cover the business logic but an integration test
+  should still be added to verify end-to-end correctness. These often catch false assumptions of how LDK works.
+- **Only make public what needs to be public** Watch out for and remove unnecessary `pub` modifiers.
+- **Do not reference the plan in code comments.** The code comments should stand on their own as context for the code and not
+  refer to plan details like commit numbers and planned followups. Genuine TODOs for deferred work like cleanups
+  or refactors are okay when not being performed shortly.
+- **Leverage the bkb-mcp tool** This gives you access to the Bitcoin Knowledge Base. Use this to discover and verify important details about the Bitcoin and Lightning protocols and how they are implemented in LDK.
+
+## Commit Messages
+The commit messaged must be focused on just the staged changes. Do not look at unstaged changes.
+Use context from the conversation to help explain the changes.
+
+Follow the seven basic rules on structure:
+  - Separate subject from body with blank line
+  - Limit subject to 50 characters (72 hard limit)
+  - Capitalize subject line
+  - No period at end of subject
+  - Use imperative mood in subject (e.g., "Fix bug" not "Fixed bug" or "Fixes bug")
+  - Wrap body at 72 characters
+  - Body explains what and why, not how. The code diff explains how
+
+Subject test: "If applied, this commit will [subject]" must make sense.
+
+In addition:
+- Avoid listing bullet points that are obvious from the code diff.
+- Nobody should ever wonder why a particular change was made. That said, keep it
+  concise and to the point.
+
+## Style
+- Rust 2024 edition
+- Functional: iterators, combinators, folds over mutable loops
+- Algebraic data types; make invalid states unrepresentable in the type system
+- Static dispatch over trait objects (trait objects only for runtime polymorphism)
+- Implement std traits (`FromStr`, `From`, `Display`) over ad-hoc methods
+- Enum variants and match arms in alphabetical order
+
+## Useful Information
+- You can find LDK source code at ../ldk-node and ../rust-lightning
+
+IMPORTANT: Check the README to see if it should be updated after completing a task