Function is_owned_by_agent 

pub(super) fn is_owned_by_agent(
    mstore: &Store,
    shell_id: &str,
    agent_block_id: &str,
) -> bool

Whether shell_id is a real view:"term" sub-block PARENTED TO agent_block_id — the actual safety property Codex asked for (PR #3177): shell_id lives in the same block-id namespace as every other pane, and Layout exposes block ids for ordinary panes, so without this check an agent could point PtyShellInput/PtyShellStop/etc. at any controller-backed block (another agent’s own CLI pane, a human’s terminal pane) and inject input into it or tear it down. Framed as parentage rather than “did PtyShell create it” (the original, narrower check) specifically so it also covers the reuse case above: a shell the HUMAN created via the drawer is just as legitimate a target as one PtyShell created itself, as long as it’s this agent’s own pane.