feat(checker): examples() and spec_files() carry the specification's files

A consumer of the checker crate needs no path into this repository.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

checker/Cargo.toml

@@ -7,6 +7,7 @@ repository.workspace = true
 description = "bookspec's example schema, its rule identifiers and the Engine trait an accounting engine implements."
 
 [dependencies]
+include_dir = "0.7"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 toml = "1"

checker/src/files.rs

@@ -0,0 +1,36 @@
+//! The specification's own files, carried by the crate: a consumer that
+//! depends on this crate (a git checkout carries the whole repository)
+//! needs no path to `examples/` or `spec/`.
+
+use include_dir::{Dir, include_dir};
+
+static EXAMPLES: Dir<'static> = include_dir!("$CARGO_MANIFEST_DIR/../examples");
+static SPEC: Dir<'static> = include_dir!("$CARGO_MANIFEST_DIR/../spec");
+
+/// The files of `dir` whose name ends in `ext`, as (file name, text),
+/// sorted by name.
+fn texts(dir: &'static Dir<'static>, ext: &str) -> Vec<(&'static str, &'static str)> {
+    let mut out: Vec<_> = dir
+        .files()
+        .filter_map(|f| {
+            let name = f.path().file_name()?.to_str()?;
+            name.ends_with(ext)
+                .then(|| (name, f.contents_utf8().expect("a UTF-8 file")))
+        })
+        .collect();
+    out.sort();
+    out
+}
+
+/// Every example (`examples/*.toml`) as (file name, text), sorted by name.
+#[must_use]
+pub fn examples() -> Vec<(&'static str, &'static str)> {
+    texts(&EXAMPLES, ".toml")
+}
+
+/// Every specification file (`spec/*.md`) as (file name, text), sorted by
+/// name.
+#[must_use]
+pub fn spec_files() -> Vec<(&'static str, &'static str)> {
+    texts(&SPEC, ".md")
+}

checker/src/lib.rs

@@ -16,10 +16,12 @@
 
 pub mod derive;
 pub mod engine;
+pub mod files;
 pub mod rules;
 pub mod schema;
 
 pub use derive::{Derivation, Derived, derive};
 pub use engine::{Claims, Engine, Refusal, RuleId, RuleIdError, fallback_refusal};
+pub use files::{examples, spec_files};
 pub use rules::{Area, Rule, Status, covered_rules, rule, rule_for_id, rule_for_refusal, rules};
 pub use schema::*;