diff --git a/hive-c0re/src/dashboard.rs b/hive-c0re/src/dashboard.rs
index 0ee6062..2a61c2a 100644
--- a/hive-c0re/src/dashboard.rs
+++ b/hive-c0re/src/dashboard.rs
@@ -157,14 +157,22 @@ async fn render_approvals(approvals: &[Approval]) -> String {
 }
 
 async fn approval_diff(agent: &str, commit_ref: &str) -> String {
-    let applied = Coordinator::agent_applied_dir(agent).join("agent.nix");
     let proposed = Coordinator::agent_proposed_dir(agent);
+    if !proposed.exists() {
+        return format!(
+            "(proposed dir {} does not exist — agent destroyed?)",
+            proposed.display()
+        );
+    }
+    if !proposed.join(".git").exists() {
+        return format!("(no git repo at {})", proposed.display());
+    }
+    let applied = Coordinator::agent_applied_dir(agent).join("agent.nix");
     let applied_text = std::fs::read_to_string(&applied).unwrap_or_default();
-    let proposed_text = match git_show(&proposed, commit_ref).await {
-        Ok(s) => s,
-        Err(e) => return format!("(error reading proposed agent.nix: {e:#})"),
-    };
-    unified_diff(&applied_text, &proposed_text)
+    match git_show(&proposed, commit_ref).await {
+        Ok(s) => unified_diff(&applied_text, &s),
+        Err(e) => format!("(error: {e:#})"),
+    }
 }
 
 async fn git_show(proposed_dir: &Path, commit_ref: &str) -> Result<String> {
@@ -173,7 +181,13 @@ async fn git_show(proposed_dir: &Path, commit_ref: &str) -> Result<String> {
         .args(["show", &format!("{commit_ref}:agent.nix")])
         .output()
         .await
-        .context("git show")?;
+        .with_context(|| {
+            format!(
+                "spawn `git show` in {} (HYPERHIVE_GIT={})",
+                proposed_dir.display(),
+                std::env::var("HYPERHIVE_GIT").unwrap_or_else(|_| "<unset>".into()),
+            )
+        })?;
     if !out.status.success() {
         anyhow::bail!(
             "git show {commit_ref}:agent.nix failed: {}",