Live findings that drove this: the "card counter 0000000000" the low-counter
notice showed is not the card's counter at all (the PoR's CNTR is a copy of
the command's counter, TS 102 225 5.2 table 3, and a rejection leaves it
zeroed); and an earlier "no card accepts the expanded format" observation was
a hand-made template whose declared length did not match its body - the card
validates the lengths and answers with a Bad format TLV.
- _cntr_low_fields(status) reports the verdict as a flag; card_cntr/
suggested_cntr and the UI's "(card counter ...)" text are gone - the value
is not observable. The notice offers a bounded Sync counter probe instead.
- POST /api/counter-probe: a doubling counter ladder (start+1, +2, +4, ...)
with a read-only command until the card accepts one, then accepted+1 is
persisted (monotonic, source counter-probe). Rejected attempts change
nothing on the card; the search stops at a ceiling (default FFFFFFFF, far
below the 40-bit maximum where the counter blocks) and after max_attempts
(default 40, clamped 1-64); a non-cntr_low failure stops it at once.
- _parse_response_scripting decodes the Bad format TLV (90, TS 101 220 table
7.20; error types per TS 102 226 table 5.12) and returns a dict; the PoR
carries bad_format/bad_format_name and _ram_step_result fails the step with
"bad format 02 (wrong length)" instead of falling through to the compact
decoder (which read the AB tag as 171 commands).
- _wrap_expanded_apdu(apdu, form) emits the definite (AA) or the indefinite
(AE 80 ... 00 00) scripting template; the RAM command formats are compact/
expanded/expanded-ae and _ram_detect_format probes compact, then both
expanded codings (the expanded probes use Le='00' and no chained GET
RESPONSE, TS 102 226 5.2.1.1). The RAM form gains a Format selector.
- Live-verified: the verdict carries no value; the probe walked
0x1000001/0x1000003 (low) then 0x1000007 (accepted, stored 0x1000008); the
ISD executes both expanded codings (R-APDU 08A0000000030000000F80, SW 9000)
and a length-mismatched template answers bad_format 02 - decoded now.
- Tests: the ladder, the probe walk + persistence, params validation, both
template forms, the Bad-format TLV (definite and plain tag styles), the
live ISD response through _decode_por, the step-result failure, and the PWA
guards; help EN/RU, docs/api.md, the repo AGENTS.md; sw cache simple-v352.
catarrh
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