diff --git a/crates/aura-cli/src/research_docs.rs b/crates/aura-cli/src/research_docs.rs
index 46c64a8..4338930 100644
--- a/crates/aura-cli/src/research_docs.rs
+++ b/crates/aura-cli/src/research_docs.rs
@@ -752,4 +752,31 @@ mod tests {
         );
         assert!(!prose.contains("CostInstrumentKeys"), "Debug leak: {prose}");
     }
+
+    /// #300 fieldtest (df_4): outside a project (no Aura.toml → `Env::std()`),
+    /// show's refusal names the missing project — the honest degradation
+    /// `validate` and `campaign runs` already share ("no Aura.toml found up
+    /// from <cwd>") — never a "project store" that does not exist. Blaming the
+    /// id sends an author in the wrong directory chasing a registration that
+    /// was never the problem. The refusal itself (Err → exit 1) is correct
+    /// and stays.
+    #[test]
+    fn show_outside_a_project_names_the_missing_aura_toml_not_the_id() {
+        let env = Env::std();
+        for (verb, result) in [
+            ("process show", show_process("deadbeef", &env)),
+            ("campaign show", show_campaign("deadbeef", &env)),
+        ] {
+            let msg = result.expect_err("show outside a project must refuse");
+            assert!(
+                msg.contains("no Aura.toml found up from"),
+                "{verb} outside a project must name the missing Aura.toml: {msg}"
+            );
+            assert!(
+                !msg.contains("not found in the project store"),
+                "{verb} outside a project must not blame the id against a \
+                 store that does not exist: {msg}"
+            );
+        }
+    }
 }