chore: add tracing to inbox, delivery, actor cache

CHANGELOG.md

@@ -6,6 +6,10 @@
 
 - Actor cache TTL now treats `fetched_at: None` as always-stale instead of always-fresh. Consumers who never populated `fetched_at` were silently getting no cache invalidation.
 
+### Other improvements
+
+- Structured tracing on key code paths: inbound activity dispatch (activity ID, source domain), outbound delivery (inbox count, retry attempts), actor cache lookups (hit/miss, staleness).
+
 ---
 
 ## [0.4.3] — 2026-07-11

src/activities/helpers.rs

@@ -35,10 +35,11 @@ pub(crate) async fn check_guards(
     actor: &Url,
     data: &Data<FederationData>,
 ) -> Result<bool, Error> {
+    let domain = actor.host_str().unwrap_or("");
+    tracing::info!(activity_id = %id, source_domain = domain, "processing inbound activity");
     if already_processed(id, data).await {
         return Ok(true);
     }
-    let domain = actor.host_str().unwrap_or("");
     if data.blocklist_repo.is_domain_blocked(domain).await? {
         tracing::info!(actor = %actor, "ignoring activity from blocked domain");
         return Ok(true);

src/service/delivery.rs

@@ -16,6 +16,11 @@ pub(crate) async fn send_with_retry(
     max_attempts: u32,
     initial_delay_secs: u64,
 ) -> Vec<anyhow::Error> {
+    tracing::info!(
+        inbox_count = sends.len(),
+        max_attempts,
+        "starting outbound delivery"
+    );
     let mut failures = vec![];
     for send in sends {
         let mut delay = std::time::Duration::from_secs(initial_delay_secs);

src/service/fetch.rs

@@ -43,9 +43,17 @@ impl ActivityPubService {
                     tracing::debug!(actor_url, "fetched_at is None, treating as stale — consider populating fetched_at in get_remote_actor()");
                     false
                 });
+            tracing::debug!(
+                actor_url,
+                cache_hit = true,
+                fresh = is_fresh,
+                "actor cache lookup"
+            );
             if is_fresh {
                 return Ok(cached);
             }
+        } else {
+            tracing::debug!(actor_url, cache_hit = false, "actor cache lookup");
         }
         let url = match Url::parse(actor_url) {
             Ok(u) => u,