test(domain): pin audit serde contracts; loosen time version; note null caveat

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Cargo.lock

@@ -361,6 +361,16 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "deranged"
+version = "0.5.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7cd812cc2bc1d69d4764bd80df88b4317eaef9e773c75226407d9bc0876b211c"
+dependencies = [
+ "powerfmt",
+ "serde_core",
+]
+
 [[package]]
 name = "digest"
 version = "0.10.7"
@@ -389,6 +399,8 @@ name = "domain"
 version = "0.0.0"
 dependencies = [
  "serde",
+ "serde_json",
+ "time",
  "uuid",
 ]
 
@@ -1067,6 +1079,12 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "num-conv"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51d515d32fb182ee37cda2ccdcb92950d6a3c2893aa280e540671c2cd0f3b1d9"
+
 [[package]]
 name = "num-integer"
 version = "0.1.46"
@@ -1201,6 +1219,12 @@ dependencies = [
  "zerovec",
 ]
 
+[[package]]
+name = "powerfmt"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "439ee305def115ba05938db6eb1644ff94165c5ab5e9420d1c1bcedbba909391"
+
 [[package]]
 name = "ppv-lite86"
 version = "0.2.21"
@@ -2013,6 +2037,36 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "time"
+version = "0.3.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f9e442fc33d7fdb45aa9bfeb312c095964abdf596f7567261062b2a7107aaabd"
+dependencies = [
+ "deranged",
+ "num-conv",
+ "powerfmt",
+ "serde_core",
+ "time-core",
+ "time-macros",
+]
+
+[[package]]
+name = "time-core"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b36ee98fd31ec7426d599183e8fe26932a8dc1fb76ddb6214d05493377d34ca"
+
+[[package]]
+name = "time-macros"
+version = "0.2.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "71e552d1249bf61ac2a52db88179fd0673def1e1ad8243a00d9ec9ed71fee3dd"
+dependencies = [
+ "num-conv",
+ "time-core",
+]
+
 [[package]]
 name = "tinystr"
 version = "0.8.3"

Cargo.toml

@@ -13,7 +13,7 @@ sqlx = { version = "0.8", features = ["runtime-tokio", "tls-rustls", "postgres",
 uuid = { version = "1", features = ["v4", "serde"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
-time = { version = "0.3.44", features = ["serde"] }
+time = { version = "0.3", features = ["serde"] }
 clap = { version = "4", features = ["derive", "env"] }
 utoipa = { version = "5", features = ["uuid"] }
 anyhow = "1"

crates/domain/src/audit.rs

@@ -44,6 +44,10 @@ pub enum AuditActor {
 }
 
 /// One field's before/after values within a change.
+///
+/// Note: after a JSON round-trip, `Some(Value::Null)` is indistinguishable from
+/// `None`. Use `None` to mean "no value"; do not encode an absent value as
+/// `Some(Value::Null)`.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct FieldChange {
     /// Field name (catalogue field key or column name).
@@ -111,10 +115,33 @@ mod tests {
     }
 
     #[test]
-    fn actor_is_adjacently_tagged() {
-        let v = serde_json::to_value(AuditActor::User(Uuid::nil())).unwrap();
-        assert_eq!(v["kind"], "user");
-        let v2 = serde_json::to_value(AuditActor::System).unwrap();
-        assert_eq!(v2["kind"], "system");
+    fn actor_serde_round_trips() {
+        for actor in [AuditActor::User(Uuid::nil()), AuditActor::System] {
+            let v = serde_json::to_value(actor).unwrap();
+            let back: AuditActor = serde_json::from_value(v).unwrap();
+            assert_eq!(back, actor);
+        }
+        assert_eq!(
+            serde_json::to_value(AuditActor::User(Uuid::nil())).unwrap()["kind"],
+            "user"
+        );
+        assert_eq!(
+            serde_json::to_value(AuditActor::System).unwrap()["kind"],
+            "system"
+        );
+    }
+
+    #[test]
+    fn action_serde_matches_as_str() {
+        for a in [
+            AuditAction::Created,
+            AuditAction::Updated,
+            AuditAction::Deleted,
+        ] {
+            assert_eq!(
+                serde_json::to_value(a).unwrap(),
+                serde_json::Value::String(a.as_str().to_owned())
+            );
+        }
     }
 }