refactor: dedup JSONB name/value helpers, add profile fields validation

Extract parse/serialize into postgres::jsonb, used by user,
remote_actor, and postgres-federation. Validate profile fields
in update_profile use case (max 4, name≤64, value≤256).

crates/adapters/postgres/src/jsonb.rs

@@ -0,0 +1,20 @@
+pub fn parse_name_value(v: Option<serde_json::Value>) -> Vec<(String, String)> {
+    v.and_then(|v| v.as_array().cloned())
+        .map(|arr| {
+            arr.into_iter()
+                .filter_map(|item| {
+                    let name = item.get("name")?.as_str()?.to_string();
+                    let value = item.get("value")?.as_str()?.to_string();
+                    Some((name, value))
+                })
+                .collect()
+        })
+        .unwrap_or_default()
+}
+
+pub fn serialize_name_value(fields: &[(String, String)]) -> serde_json::Value {
+    fields
+        .iter()
+        .map(|(n, v)| serde_json::json!({"name": n, "value": v}))
+        .collect()
+}

crates/adapters/postgres/src/lib.rs

@@ -8,6 +8,7 @@ pub mod engagement;
 pub mod failed_event;
 pub mod feed;
 pub mod follow;
+pub(crate) mod jsonb;
 pub mod like;
 pub mod notification;
 pub mod outbox;

crates/adapters/postgres/src/remote_actor.rs

@@ -23,11 +23,7 @@ impl RemoteActorRepository for PgRemoteActorRepository {
         } else {
             Some(a.also_known_as.iter().map(|s| s.as_str()).collect())
         };
-        let attachment_json: serde_json::Value = a
-            .attachment
-            .iter()
-            .map(|(n, v)| serde_json::json!({"name": n, "value": v}))
-            .collect();
+        let attachment_json = crate::jsonb::serialize_name_value(&a.attachment);
         sqlx::query(
             "INSERT INTO remote_actors(url,handle,display_name,avatar_url,last_fetched_at,
              bio,banner_url,outbox_url,followers_url,following_url,also_known_as,attachment)
@@ -101,19 +97,7 @@ impl RemoteActorRepository for PgRemoteActorRepository {
                 following_url: r.following_url,
                 inbox_url: r.inbox_url,
                 shared_inbox_url: r.shared_inbox_url,
-                attachment: r
-                    .attachment
-                    .and_then(|v| v.as_array().cloned())
-                    .map(|arr| {
-                        arr.into_iter()
-                            .filter_map(|item| {
-                                let name = item.get("name")?.as_str()?.to_string();
-                                let value = item.get("value")?.as_str()?.to_string();
-                                Some((name, value))
-                            })
-                            .collect()
-                    })
-                    .unwrap_or_default(),
+                attachment: crate::jsonb::parse_name_value(r.attachment),
             })
         })
     }

crates/adapters/postgres/src/user/mod.rs

@@ -37,20 +37,6 @@ pub struct UserRow {
     pub updated_at: DateTime<Utc>,
 }
 
-fn parse_profile_fields(v: Option<serde_json::Value>) -> Vec<(String, String)> {
-    v.and_then(|v| v.as_array().cloned())
-        .map(|arr| {
-            arr.into_iter()
-                .filter_map(|item| {
-                    let name = item.get("name")?.as_str()?.to_string();
-                    let value = item.get("value")?.as_str()?.to_string();
-                    Some((name, value))
-                })
-                .collect()
-        })
-        .unwrap_or_default()
-}
-
 impl From<UserRow> for User {
     fn from(r: UserRow) -> Self {
         User {
@@ -63,7 +49,7 @@ impl From<UserRow> for User {
             avatar_url: r.avatar_url,
             header_url: r.header_url,
             custom_css: r.custom_css,
-            profile_fields: parse_profile_fields(r.profile_fields),
+            profile_fields: crate::jsonb::parse_name_value(r.profile_fields),
             local: r.local,
             created_at: r.created_at,
             updated_at: r.updated_at,
@@ -238,11 +224,7 @@ impl UserReader for PgUserRepository {
 #[async_trait]
 impl UserWriter for PgUserRepository {
     async fn save(&self, user: &User) -> Result<(), DomainError> {
-        let profile_fields_json: serde_json::Value = user
-            .profile_fields
-            .iter()
-            .map(|(n, v)| serde_json::json!({"name": n, "value": v}))
-            .collect();
+        let profile_fields_json = crate::jsonb::serialize_name_value(&user.profile_fields);
         sqlx::query(
             "INSERT INTO users (id,username,email,password_hash,display_name,bio,avatar_url,header_url,custom_css,profile_fields,local,created_at,updated_at)
              VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13)
@@ -290,13 +272,10 @@ impl UserWriter for PgUserRepository {
         user_id: &UserId,
         input: UpdateProfileInput,
     ) -> Result<(), DomainError> {
-        let profile_fields_json: Option<serde_json::Value> =
-            input.profile_fields.as_ref().map(|fields| {
-                fields
-                    .iter()
-                    .map(|(n, v)| serde_json::json!({"name": n, "value": v}))
-                    .collect()
-            });
+        let profile_fields_json: Option<serde_json::Value> = input
+            .profile_fields
+            .as_ref()
+            .map(|f| crate::jsonb::serialize_name_value(f));
         sqlx::query(
             "UPDATE users SET \
              display_name    = COALESCE($2, display_name), \

crates/application/src/use_cases/profile/mod.rs

@@ -1,4 +1,7 @@
 const MAX_TOP_FRIENDS: usize = 8;
+const MAX_PROFILE_FIELDS: usize = 4;
+const MAX_FIELD_NAME_LEN: usize = 64;
+const MAX_FIELD_VALUE_LEN: usize = 256;
 
 use bytes::Bytes;
 use domain::{
@@ -55,6 +58,20 @@ pub async fn update_profile(
     user_id: &UserId,
     input: UpdateProfileInput,
 ) -> Result<(), DomainError> {
+    if let Some(ref fields) = input.profile_fields {
+        if fields.len() > MAX_PROFILE_FIELDS {
+            return Err(DomainError::InvalidInput(format!(
+                "profile fields: max {MAX_PROFILE_FIELDS}"
+            )));
+        }
+        for (name, value) in fields {
+            if name.len() > MAX_FIELD_NAME_LEN || value.len() > MAX_FIELD_VALUE_LEN {
+                return Err(DomainError::InvalidInput(
+                    "profile field name or value too long".into(),
+                ));
+            }
+        }
+    }
     users.update_profile(user_id, input).await?;
     events
         .publish(&DomainEvent::ProfileUpdated {