diff --git a/wfe-yaml/src/executors/shell.rs b/wfe-yaml/src/executors/shell.rs
index da9e55d..6db5a43 100644
--- a/wfe-yaml/src/executors/shell.rs
+++ b/wfe-yaml/src/executors/shell.rs
@@ -92,8 +92,21 @@ impl StepBody for ShellStep {
                 && let Some(eq_pos) = rest.find('=')
             {
                 let name = rest[..eq_pos].trim().to_string();
-                let value = rest[eq_pos + 1..].to_string();
-                outputs.insert(name, serde_json::Value::String(value));
+                let raw_value = rest[eq_pos + 1..].to_string();
+                // Auto-convert typed values from string annotations
+                let value = match raw_value.as_str() {
+                    "true" => serde_json::Value::Bool(true),
+                    "false" => serde_json::Value::Bool(false),
+                    "null" => serde_json::Value::Null,
+                    s if s.parse::<i64>().is_ok() => {
+                        serde_json::Value::Number(s.parse::<i64>().unwrap().into())
+                    }
+                    s if s.parse::<f64>().is_ok() => {
+                        serde_json::json!(s.parse::<f64>().unwrap())
+                    }
+                    _ => serde_json::Value::String(raw_value),
+                };
+                outputs.insert(name, value);
             }
         }
 
diff --git a/wfe-yaml/tests/e2e_yaml.rs b/wfe-yaml/tests/e2e_yaml.rs
index 547a602..5325385 100644
--- a/wfe-yaml/tests/e2e_yaml.rs
+++ b/wfe-yaml/tests/e2e_yaml.rs
@@ -91,7 +91,7 @@ workflow:
             assert_eq!(greeting.as_str(), Some("hello"));
         }
         if let Some(count) = data.get("count") {
-            assert_eq!(count.as_str(), Some("42"));
+            assert_eq!(count.as_i64(), Some(42)); // auto-converted from string "42"
         }
     }
 }
diff --git a/wfe-yaml/tests/shell.rs b/wfe-yaml/tests/shell.rs
index f5f5834..6b2de05 100644
--- a/wfe-yaml/tests/shell.rs
+++ b/wfe-yaml/tests/shell.rs
@@ -106,7 +106,7 @@ workflow:
             assert_eq!(greeting.as_str(), Some("hello"));
         }
         if let Some(count) = data.get("count") {
-            assert_eq!(count.as_str(), Some("42"));
+            assert_eq!(count.as_i64(), Some(42)); // auto-converted from string "42"
         }
         if let Some(path) = data.get("path") {
             assert_eq!(path.as_str(), Some("/usr/local/bin"));