The simplification deletes sandbox_mode and approval_policy from the parent branch's SQLite layouts. Restoring master's older version numbers would violate the monotonic schema contract and could make a database created by the parent look current under a different layout.
Advance durable session persistence from schema 11 to 12 and the disposable session-query index from 6 to 7. The former rejects the incompatible parent layout; the latter resets its derived tables through the existing version-mismatch path.
JSONL shares SESSION_FORMAT_VERSION 0 during pre-release, so explicitly reject the retired sandboxMode and approvalPolicy header fields instead of silently dropping the only inherited policy facts from a parent-produced child log. New logs carry those facts as ordinary seeded events.
Focused JSONL, SQLite persistence, and SQLite query suites cover all affected source lines and branches.
Tianyi Cui
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