Why: deliverable prompts already tell the model to generate Office files
with run_python and register them, but the executors were never
registered, so calls missed the registry and fell back to text-only
write_artifact.
Evidence: go test ./... — 19 packages ok, including echo/script-retention,
empty-script and runtime.exec gate, process-group timeout, python ZIP
magic, and ExecuteTool backfill of register_artifact after run_python.
Scripts stay under the session .agent/ directory; bash/python3 are
resolved to absolute paths; timeout kills the process group.
Impact: models can execute workspace scripts and register binary
deliverables. runtime.exec=false still fail-closes the whole family.
Office extensions now get real MIME types so binary bytes are not
indexed as text.
Refs: task feature/exec-interpreters
Co-authored-by: Cursor <cursoragent@cursor.com>