diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..7454d38
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,54 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+env:
+  CARGO_TERM_COLOR: always
+  RUSTFLAGS: "-Dwarnings"
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check-test:
+    name: Check & Test
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: Swatinem/rust-cache@v2
+      - name: Format
+        run: cargo fmt -- --check
+      - name: Clippy
+        run: cargo clippy --locked --all-targets
+      - name: Test
+        run: |
+          git config --global user.email "ci@yolog.dev"
+          git config --global user.name "yoagent-state-ci"
+          cargo test --locked
+
+  # Enforce the DECLARED rust-version with a real compiler. Cargo never
+  # verifies rust-version against the code — 0.4.0/0.4.1 shipped a let-chain
+  # (needs 1.88) while declaring 1.85, breaking downstream MSRV builds
+  # (yologdev/yoagent#68). This job makes that class of lie impossible.
+  msrv:
+    name: MSRV (1.85)
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@1.85
+      - uses: Swatinem/rust-cache@v2
+      - name: Check
+        # --locked: uuid/getrandom sit at exactly rust-version 1.85 (zero
+        # headroom) — enforce the committed lock so a regeneration can't
+        # silently move the gate.
+        run: cargo check --locked --all-targets
diff --git a/src/state.rs b/src/state.rs
index 1ecee72..b7f0e03 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -56,18 +56,17 @@ impl<S: EventStore> YoAgentState<S> {
         let events = self.store.scan().await?;
         let mut open: Option<(RunId, EventId)> = None;
         for event in &events {
-            let run_id = event
-                .payload
-                .get("run_id")
-                .and_then(|v| v.as_str().map(RunId::from).or_else(|| {
-                    serde_json::from_value::<RunId>(v.clone()).ok()
-                }));
+            let run_id = event.payload.get("run_id").and_then(|v| {
+                v.as_str()
+                    .map(RunId::from)
+                    .or_else(|| serde_json::from_value::<RunId>(v.clone()).ok())
+            });
             match (event.kind.as_str(), run_id) {
                 ("run.started", Some(id)) => open = Some((id, event.id.clone())),
-                ("run.finished", Some(id)) => {
-                    if open.as_ref().is_some_and(|(o, _)| *o == id) {
-                        open = None;
-                    }
+                // Guard fall-through hits the `_ => {}` arm — same no-op as
+                // the previous nested if.
+                ("run.finished", Some(id)) if open.as_ref().is_some_and(|(o, _)| *o == id) => {
+                    open = None;
                 }
                 _ => {}
             }
diff --git a/tests/failure_paths.rs b/tests/failure_paths.rs
index 1d93e2d..7587909 100644
--- a/tests/failure_paths.rs
+++ b/tests/failure_paths.rs
@@ -147,12 +147,19 @@ async fn resume_open_run_recovers_the_marker_across_processes() {
 
     // events in the resumed process chain + correlate to the original run
     state2
-        .record_event(Event::new(actor(), "observation.created", json!({"id": "o1"})))
+        .record_event(Event::new(
+            actor(),
+            "observation.created",
+            json!({"id": "o1"}),
+        ))
         .await
         .unwrap();
     let events = state2.store().scan().await.unwrap();
     let started = events.iter().find(|e| e.kind == "run.started").unwrap();
-    let obs = events.iter().find(|e| e.kind == "observation.created").unwrap();
+    let obs = events
+        .iter()
+        .find(|e| e.kind == "observation.created")
+        .unwrap();
     assert_eq!(obs.causation_id.as_ref(), Some(&started.id));
     assert_eq!(obs.correlation_id.as_deref(), Some("run_x"));
 
diff --git a/tests/run_chaining.rs b/tests/run_chaining.rs
index 59ba495..7d91faf 100644
--- a/tests/run_chaining.rs
+++ b/tests/run_chaining.rs
@@ -75,11 +75,7 @@ async fn events_inside_a_run_chain_to_run_started() {
         .await
         .unwrap();
     let events = state.store().scan().await.unwrap();
-    let after = events
-        .iter()
-        .filter(|e| e.kind == "goal.created")
-        .last()
-        .unwrap();
+    let after = events.iter().rfind(|e| e.kind == "goal.created").unwrap();
     assert_eq!(after.causation_id, None);
     assert_eq!(after.correlation_id, None);
 }