hook session-end exits 0 on every path by design and reports its outcome only as human stderr text, so a programmatic caller can detect success solely by string-matching 'abcd history: staged' or 'already staged'. A local adaptor lab shipped a silent permanent-loss bug from exactly this: non-matching stderr was first treated as success, and finished sessions were watermarked as captured when staging had failed. Give the hook a machine-readable result channel — a JSON line on stdout, or a documented stable contract — without breaking the never-wedge-the-session exit-0 behaviour toward the host.

hook session-end exits 0 on every path by design and reports its outcome only as human stderr text, so a programmatic caller can detect success solely by string-matching 'abcd history: staged' or 'already staged'. A local adaptor lab shipped a silent permanent-loss bug from exactly this: non-matching stderr was first treated as success, and finished sessions were watermarked as captured when staging had failed. Give the hook a machine-readable result channel — a JSON line on stdout, or a documented stable contract — without breaking the never-wedge-the-session exit-0 behaviour toward the host.

Grounds

• pursued: a programmatic caller reads whether a transcript was staged from a stable JSON field instead of stderr prose; a staging failure reported as captured, or a path that writes no line under --json, would show it wrong