- Replace all sqlite::open().unwrap() per-request with shared Arc<Mutex<Connection>>
- Add Mutex poisoning recovery in all cfg.lock() and db.lock() calls
- Fix std::str::from_utf8().unwrap() with safe match → 400 Bad Request
- Fix timestamp_nanos_opt().unwrap() with safe match
- Fix panic on RPC client failure (bal-pusher): error log + sleep + retry
- Fix ZMQ socket connect with retry loop (bal-pusher)
- Add ZMQ_RCVTIMEO=5000 and match recv for graceful timeout (bal-pusher)
- Fix ZMQ subscribe error with match instead of unwrap (bal-pusher)
- Add unwrap_or for all tbl_stats row fields in echo_stats (prevent NULL panic)
- Add panic_regression_tests.rs: test mutex poisoning recovery and NULL unwrap_or
All tests pass: cargo test --test panic_regression_tests + sql_injection_tests
Build verified: cargo check --bin=bal-server --bin=bal-pusher
