ea42bc6d20
* Regression tests: a PDU the codec cannot read costs that PDU, not the link * Refuse a single unreadable PDU instead of the whole link * smscsim interop asserts the first attempt gets every DLR * Record the smscsim sequence number defect as fixed * One framing rule and one response-command lookup, per the architecture review * Apply the stability review's nits: honest sessionError docs and one link-survives assertion