diff --git a/src/server/actors/repo/branch.rs b/src/server/actors/repo/branch.rs
index 669a0f7..b64778a 100644
--- a/src/server/actors/repo/branch.rs
+++ b/src/server/actors/repo/branch.rs
@@ -1,16 +1,68 @@
+use tracing::{error, warn};
+
 use crate::server::forge;
 
+use super::StartMonitoring;
+
 #[tracing::instrument(fields(forge_name = %repo_details.forge.name, repo_name = %repo_details.name))]
 pub async fn validate_positions(
     repo_details: crate::server::config::RepoDetails,
     config: crate::server::config::RepoConfig,
-    _addr: actix::prelude::Addr<super::RepoActor>,
+    addr: actix::prelude::Addr<super::RepoActor>,
     net: kxio::network::Network,
 ) {
-    let _commit_histories = match repo_details.forge.forge_type {
+    let commit_histories = match repo_details.forge.forge_type {
         crate::server::config::ForgeType::ForgeJo => {
-            forge::forgejo::get_commit_histories(&repo_details, &config, &net)
+            forge::forgejo::get_commit_histories(&repo_details, &config, &net).await
         }
     };
-    todo!()
+    let commit_histories = match commit_histories {
+        Ok(commit_histories) => commit_histories,
+        Err(err) => {
+            error!(?err, "Failed to get commit histories");
+            return;
+        }
+    };
+
+    let Some(main) = commit_histories.main.first().cloned() else {
+        warn!("No commits on main branch '{}'", config.branches().main());
+        return;
+    };
+    let next_commits = commit_histories
+        .next
+        .into_iter()
+        .take(2)
+        .collect::<Vec<_>>();
+    if !next_commits.contains(&main) {
+        warn!(
+            "Main branch '{}' is not on the same commit as next branch '{}', or it's parent",
+            config.branches().main(),
+            config.branches().next()
+        );
+        return;
+    }
+    let next = next_commits[0].clone();
+    let dev_has_next = commit_histories
+        .dev
+        .iter()
+        .any(|commit| commit == &next_commits[0]);
+    if !dev_has_next {
+        warn!(
+            "Dev branch '{}' is not based on next branch '{}'",
+            config.branches().dev(),
+            config.branches().next()
+        );
+        return; // dev is not based on next
+    }
+    let dev_has_main = commit_histories.dev.iter().any(|commit| commit == &main);
+    if !dev_has_main {
+        warn!(
+            "Dev branch '{}' is not based on main branch '{}'",
+            config.branches().dev(),
+            config.branches().main()
+        );
+        return;
+    }
+    let dev = commit_histories.dev[0].clone();
+    addr.do_send(StartMonitoring { main, next, dev });
 }
diff --git a/src/server/actors/repo/mod.rs b/src/server/actors/repo/mod.rs
index eb8693f..775192f 100644
--- a/src/server/actors/repo/mod.rs
+++ b/src/server/actors/repo/mod.rs
@@ -5,7 +5,10 @@ use actix::prelude::*;
 use kxio::network::Network;
 use tracing::info;
 
-use crate::server::config::{RepoConfig, RepoDetails};
+use crate::server::{
+    config::{RepoConfig, RepoDetails},
+    forge,
+};
 
 pub struct RepoActor {
     details: RepoDetails,
@@ -56,3 +59,17 @@ impl Handler<LoadedConfig> for RepoActor {
             .wait(ctx);
     }
 }
+
+#[derive(Message)]
+#[rtype(result = "()")]
+pub struct StartMonitoring {
+    pub main: forge::Commit,
+    pub next: forge::Commit,
+    pub dev: forge::Commit,
+}
+impl Handler<StartMonitoring> for RepoActor {
+    type Result = ();
+    fn handle(&mut self, _msg: StartMonitoring, _ctx: &mut Self::Context) -> Self::Result {
+        info!(%self.details, "Monitoring started");
+    }
+}