Implement ObserverEngine

Cargo.toml

@@ -33,9 +33,11 @@ gungraun = "0.17.0"
 indicatif = "0.18.4"
 inventory = "0.3.21"
 predicates = "3.1.3"
+rayon = "1.10"
 serde = { version = "1.0.219", features = ["derive"] }
 serde_json = "1.0.145"
 tempfile = "3.21.0"
+thread_local = "1.1"
 toml = "0.9.5"
 tracing = "0.1.41"
 sha1 = "0.10"

herostratus/Cargo.toml

@@ -25,9 +25,11 @@ directories.workspace = true
 eyre.workspace = true
 gix.workspace = true
 inventory.workspace = true
+rayon.workspace = true
 serde.workspace = true
 serde_json.workspace = true
 tempfile.workspace = true
+thread_local.workspace = true
 toml.workspace = true
 tracing.workspace = true
 tracing-subscriber.workspace = true

herostratus/src/observer/commit_context.rs

@@ -2,7 +2,7 @@
 ///
 /// Rules see `CommitContext` + `Observation` -- they never touch the raw `gix::Commit`. Mailmap
 /// resolution happens once in the ObserverEngine before constructing this struct.
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct CommitContext {
     pub oid: gix::ObjectId,
     pub author_name: String,

herostratus/src/observer/mod.rs

@@ -17,4 +17,6 @@ pub use observation::Observation;
 pub use observer::{DiffAction, Observer};
 #[expect(unused)]
 pub(crate) use observer_data::ObserverData;
+#[expect(unused)]
+pub(crate) use observer_engine::ObserverEngine;
 pub use observer_factory::ObserverFactory;

herostratus/src/observer/observer.rs

@@ -31,7 +31,7 @@ use super::observation::Observation;
 /// 2. Implement the [Observer] trait in the [impls](super::impls) module
 /// 3. Register the observer via [inventory::submit!] with an
 ///    [ObserverFactory](super::ObserverFactory)
-pub trait Observer {
+pub trait Observer: Send {
     /// The observation variant this observer emits.
     fn emits(&self) -> std::mem::Discriminant<Observation>;
 
@@ -59,7 +59,7 @@ pub trait Observer {
     /// Return [DiffAction::Cancel] to stop receiving further changes for this commit.
     fn on_diff_change(
         &mut self,
-        _change: &gix::object::tree::diff::Change,
+        _change: &gix::object::tree::diff::ChangeDetached,
         _repo: &gix::Repository,
     ) -> eyre::Result<DiffAction> {
         Ok(DiffAction::Cancel)

herostratus/src/observer/observer_data.rs

@@ -2,8 +2,7 @@ use super::commit_context::CommitContext;
 use super::observation::Observation;
 
 /// Messages sent through the channel from the ObserverEngine to the RuleEngine.
-#[derive(Debug)]
-#[expect(unused)]
+#[derive(Debug, PartialEq, Eq)]
 pub enum ObserverData {
     /// Begins a new commit. Sent once before any observations for that commit.
     CommitStart(CommitContext),