c0re: chown per-agent state writes to agent uid:gid (#673)

hive-c0re/src/forge.rs

@@ -162,6 +162,24 @@ fn extract_token(output: &str) -> Option<String> {
         .map(str::to_owned)
 }
 
+/// Best-effort chown `path` to the agent's container-local uid/gid.
+/// Closes the gap where c0re (running as root on the host) writes
+/// per-agent state files that the agent's non-root unix user then
+/// can't read until the next container activation runs the chown
+/// fixup in `harness-base.nix` (#673).
+///
+/// Silently no-ops when the container hasn't been built yet (passwd
+/// file absent) or when the chown syscall fails — the activation
+/// script remains the safety net.
+fn chown_to_agent(name: &str, path: &Path) {
+    let Some((uid, gid)) = crate::lifecycle::agent_uid_gid(name) else {
+        return;
+    };
+    if let Err(e) = std::os::unix::fs::chown(path, Some(uid), Some(gid)) {
+        tracing::debug!(%name, path = %path.display(), error = %e, "forge: chown to agent failed");
+    }
+}
+
 /// Canonical email address for a hive agent's Forgejo account.
 /// Must match the `user.email` set by `meta::render_flake` so commits
 /// by the agent link back to their Forgejo profile page.
@@ -335,6 +353,7 @@ async fn mint_and_persist_token(name: &str, path: &Path, scopes: &str) -> Result
     std::fs::write(path, format!("{token}\n"))
         .with_context(|| format!("write token to {}", path.display()))?;
     let _ = std::fs::set_permissions(path, std::fs::Permissions::from_mode(0o600));
+    chown_to_agent(name, path);
     tracing::info!(%name, path = %path.display(), "forge: persisted access token");
     Ok(())
 }