c0re: address argus review nits on #434

hive-c0re/src/flake_check.rs

@@ -53,14 +53,15 @@ async fn read_lock_at_tag(repo: &Path, tag: &str) -> Result<Option<String>> {
         .with_context(|| format!("git show {spec} in {}", repo.display()))?;
     if !out.status.success() {
         let stderr = String::from_utf8_lossy(&out.stderr);
-        // git uses different messages for "path not in tree" depending
-        // on version + whether the path collides with an on-disk file.
-        // Treat any of them as "no flake.lock in this commit" rather
-        // than a hard failure — an agent with empty `inputs = { }` is
-        // a legitimate, dedup-clean state.
+        // git uses two different messages for "path not in tree"
+        // depending on whether the path also collides with an on-disk
+        // file. Both translate to "no flake.lock in this commit" —
+        // a legitimate, dedup-clean state for an agent with empty
+        // `inputs = { }`. Any other git failure (permission denied,
+        // ref-not-found, etc.) propagates as a hard error rather than
+        // being silently swallowed.
         if stderr.contains("does not exist")
             || stderr.contains("exists on disk, but not in")
-            || stderr.contains("Path '")
         {
             return Ok(None);
         }
@@ -242,6 +243,12 @@ async fn lock_in_sync_inner(worktree: &Path) -> Result<()> {
         .await
         .ok();
 
+    // An agent that declares inputs in flake.nix but ships no
+    // flake.lock at all hits this branch (committed = None,
+    // regenerated = Some(...)). That's a deliberate reject: every
+    // agent with inputs MUST commit its lock, otherwise meta's
+    // dedup pass has nothing to introspect and the broken state
+    // leaks downstream. Treated identically to a stale lock.
     if committed.as_deref() != regenerated.as_deref() {
         anyhow::bail!(
             "flake.lock is out of sync with flake.nix — `nix flake lock` produces a different lock. \

hive-c0re/src/manager_server.rs

@@ -635,8 +635,11 @@ async fn submit_apply_commit(
         .map_err(|e| anyhow::anyhow!("persist fetched_sha: {e:#}"))?;
     // #317 pre-flight gates: both reject the apply before approval if
     // the agent's flake state would inflate meta's lock with duplicates
-    // or lie about what nix will fetch. Order matters — sync first so
-    // the dedup pass acts on the lock nix would actually produce.
+    // or lie about what nix will fetch. Both checks independently read
+    // `<tag>:flake.lock` via git — they don't share state. Order matters
+    // only for early-exit + messaging: sync first means a stale lock
+    // bails with the actionable "run `nix flake lock`" hint rather than
+    // a dedup pass on a lock nix would never produce.
     //
     // Runs after `set_fetched_sha` so the failed row carries the sha
     // that broke. Both failure paths mark + emit, then bail.