• Safer render paths: recover from poisoned mutex, remove unwrap panics from container overlay, replace unreachable! with safe fallbacks in provider and tunnel forms
• Faster host sorting: cache lowercased keys instead of allocating per comparison. HashSet dedup for group tab ordering
• Allocation-free host width calculation in the host list renderer
• Container cache write errors now surface in the debug log instead of being silently swallowed
• Internal: split handler.rs (11k lines) and app.rs (11k lines) into focused submodules. No behavior change