From ef968c11dd1f97d3b802dc6426c6b47175f15c44 Mon Sep 17 00:00:00 2001
From: damocles <damocles@hyperhive>
Date: Sun, 31 May 2026 00:28:04 +0200
Subject: [PATCH] c0re: dedupe chown_to_agent into lifecycle (argus #678)

---
 hive-c0re/src/forge.rs     | 20 +-------------------
 hive-c0re/src/lifecycle.rs | 17 +++++++++++++++++
 hive-c0re/src/matrix.rs    | 16 +---------------
 3 files changed, 19 insertions(+), 34 deletions(-)

diff --git a/hive-c0re/src/forge.rs b/hive-c0re/src/forge.rs
index 95343ad8..b08440c8 100644
--- a/hive-c0re/src/forge.rs
+++ b/hive-c0re/src/forge.rs
@@ -162,24 +162,6 @@ 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.
@@ -353,7 +335,7 @@ 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);
+    crate::lifecycle::chown_to_agent(name, path, "forge");
     tracing::info!(%name, path = %path.display(), "forge: persisted access token");
     Ok(())
 }
diff --git a/hive-c0re/src/lifecycle.rs b/hive-c0re/src/lifecycle.rs
index 93e10594..e3051517 100644
--- a/hive-c0re/src/lifecycle.rs
+++ b/hive-c0re/src/lifecycle.rs
@@ -128,6 +128,23 @@ pub fn agent_uid_gid(agent_name: &str) -> Option<(u32, u32)> {
     None
 }
 
+/// Best-effort `chown(path, agent_uid, agent_gid)`. Resolves the agent's
+/// uid/gid via [`agent_uid_gid`] and shells out to `std::os::unix::fs::chown`.
+/// Silently no-ops when the container isn't built yet (`None` from
+/// [`agent_uid_gid`]) and logs at debug on chown syscall failure — the
+/// activation script in `harness-base.nix` is the steady-state safety
+/// net. Used by per-agent state writers in `forge` + `matrix` so the
+/// agent can read the file without waiting for the next container
+/// rebuild (#673).
+pub fn chown_to_agent(name: &str, path: &Path, subsystem: &str) {
+    let Some((uid, gid)) = agent_uid_gid(name) else {
+        return;
+    };
+    if let Err(e) = std::os::unix::fs::chown(path, Some(uid), Some(gid)) {
+        tracing::debug!(%name, %subsystem, path = %path.display(), error = %e, "chown to agent failed");
+    }
+}
+
 fn validate(name: &str) -> Result<()> {
     if name.is_empty() {
         bail!("agent name must not be empty");
diff --git a/hive-c0re/src/matrix.rs b/hive-c0re/src/matrix.rs
index 86948f63..0e0099b6 100644
--- a/hive-c0re/src/matrix.rs
+++ b/hive-c0re/src/matrix.rs
@@ -274,25 +274,11 @@ pub async fn ensure_user_for(
     std::fs::write(&path, format!("{access_token}\n"))
         .with_context(|| format!("matrix: write token to {}", path.display()))?;
     let _ = std::fs::set_permissions(&path, std::fs::Permissions::from_mode(0o600));
-    chown_to_agent(name, &path);
+    crate::lifecycle::chown_to_agent(name, &path, "matrix");
     tracing::info!(%name, path = %path.display(), "matrix: registered user + persisted access token");
     Ok(())
 }
 
-/// Best-effort chown `path` to the agent's container-local uid/gid.
-/// Mirrors `forge::chown_to_agent` for the matrix access-token write —
-/// closes the gap where c0re (root on host) writes a file the agent's
-/// non-root unix user then can't read until the next activation runs
-/// the harness-base.nix chown fixup (#673).
-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, "matrix: chown to agent failed");
-    }
-}
-
 /// Register a matrix account for `name` with the supplied `password`
 /// and return the freshly-minted access token. Unlike [`ensure_user_for`],
 /// the token is **not** persisted to disk — the caller is responsible