doc: add CONTRIBUTING.md, add coverage task

Author: ada-x64

.config/mise.toml

@@ -111,16 +111,20 @@ act -P ubuntu-24.04=ghcr.io/catthehacker/ubuntu:act-24.04 \
 tools = { "cargo:cargo-nextest" = "latest" }
 description = "Run tests for a specific package or all packages"
 usage = """
-    flag "--rust-log <rust_log>" env="RUST_LOG"
-    arg "[rest]" double_dash = "required" default="" help="Passed directly to `cargo nextest`. Use `mise test -- help` for nextest help."
+    arg "[rest]" default="r --workspace" help="Passed directly to `cargo nextest`"
 """
 run = """
-if [ $usage_rust_log ]; then RUST_LOG=$usage_rust_log; fi
-if [ -n "${usage_rest?}" ]; then
-    cargo nextest ${usage_rest?}
-else
-    cargo nextest run --workspace
-fi
+cargo nextest ${usage_rest}
+"""
+
+[tasks.coverage]
+tools = { "cargo:cargo-llvm-cov" = "latest", "cargo:cargo-nextest" = "latest" }
+description = "Get test coverage report."
+usage = """
+    arg "[rest]" default="--html --open"
+"""
+run = """
+RUSTFLAGS=-Zcodegen-backend=llvm cargo llvm-cov nextest --html --open
 """
 
 # LOCAL #######################################################################

CONTRIBUTING.md

@@ -0,0 +1,41 @@
+# How to work on this project
+
+Thanks for your interest!
+
+You should have a few prerequisite tools installed. Most importantly, you'll
+need [mise](https://mise.jdx.dev/), an environment manager and task runner.
+
+Once you install mise, run `mise install` and `mise run` to get all the
+necessary tools and view the available actions.
+
+## Testing
+
+Tests are handled
+with [cargo-nextest](https://github.com/nextest-rs/nextest). Test coverage is
+generated with [cargo-llvm-cov.](https://github.com/taiki-e/cargo-llvm-cov)
+Generally, tests should be built out using
+[q_test_harness.](./crates/test_harness) Read that documentation to learn
+common testing patterns.
+
+You can test CI locally by running `mise ci`. You can change which workflow and
+which matrix parameters are set by using this sort of pattern:
+
+```mise ci -W ./.github/workflows/ci.yml --matrix target:x86_64-unknown-linux-gnu```
+
+## PRs and Commit Messages
+
+PRs, when accepted, should be squashed into a single commit using [git
+convention](https://www.conventionalcommits.org/en/v1.0.0/) for the message.
+This is used to automatically generate changelogs when we publish.
+
+PRs are expected to follow best practices. If you author a PR using an LLM,
+please disclose that you have done so. All CI checks should pass.
+
+
+## Publishing
+
+Crates are published using
+[cargo-smart-release.](https://github.com/crate-ci/cargo-release) Contributors
+generally shouldn't be running this, so this documentation is mostly for me :p
+Crates should have at least 80% test coverage before release. Currently there
+are hooks to enforce this, so use your best judgement.