rtl8733b: drop the dead _tssi_cck member, fix the doc drift

Review follow-ups on #396, all doc/consistency — no behavioural change.

- `_tssi_cck` went write-only when `select_tssi_rate_table` was deleted: set
  in `configure_tx_power`, cleared in `Stop()`, read nowhere. Deleted rather
  than kept for a reader that does not exist.

- The table-selection comment claimed vendor-equivalent keying without saying
  the canonical flow reaches it with no mode configured — txdemo calls
  `InitWrite` before `SetTxMode`, so `_tx_mode_default` is usually unset and a
  `DEVOURER_TX_RATE=1M` session loads the OFDM/HT table. Left as is (the two
  tables are the same bits below +18 and the part plateaus at +8), but the
  comment now says so instead of implying parity.

- Root `CLAUDE.md` and `src/rtl8733b/CLAUDE.md` still placed the `disable_cca`
  warning at `InitWrite` after this PR moved it to `bring_up_to_phy`.

- `docs/rtl8733b.md` narrated two runs in terms of per-frame TSSI table
  switching, a path this PR deletes and which cannot be reproduced on this
  tree. The rate-coverage and thermal evidence stays; the mechanism framing
  goes, with the tables' identity at those deltas stated instead.

53/53, RTL8733B-only ASan+UBSan 49/49.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: snokvist

CLAUDE.md

@@ -334,7 +334,8 @@ Behavioural traps the per-field docs can't carry:
   been located and measured there, so `SetCcaMode(true)` throws (loudly, but
   without tearing the session down) while `SetCcaMode(false)`, the state its
   MAC bring-up already leaves programmed, succeeds as a no-op; setting the
-  config knob warns at `InitWrite` and airs with carrier-sense. Does NOT apply
+  config knob warns once at bring-up (RX-only sessions included) and airs
+  with carrier-sense. Does NOT apply
   the vendor BB CCA-off writes (they deafen the RX). RX-decode side is a
   separate null (`tests/dis_cca_onair.sh`).
 

docs/rtl8733b.md

@@ -94,9 +94,9 @@ rather than in modulation. Treat the whole HT column as one flat band around
 90-100% until something moves it by more than the probe noise.
 
 A mixed run alternating all eight rates (1/2/5.5/11 Mbps CCK, 6 Mbps OFDM,
-MCS0/4/7) submitted 250 frames through a CCK/OFDM TSSI table switch on every
-frame. The witness decoded all eight `rate_hw` values on air with valid FCS,
-every frame at 20 MHz with STBC and LDPC clear, matching the forced-BCC
+MCS0/4/7) submitted 250 frames, crossing the CCK/OFDM rate-class boundary on
+every frame. The witness decoded all eight `rate_hw` values on air with valid
+FCS, every frame at 20 MHz with STBC and LDPC clear, matching the forced-BCC
 contract.
 
 RX aggregation is capped at 12 KiB (`rtl8733b::kRxAggregateBytes8733b`) because
@@ -120,10 +120,12 @@ the meter is a PA-bias tracking index rather than a calibrated junction
 temperature, so it is not sound input for a TX gate
 (`docs/warm-tx-degradation.md`). During the mixed CCK/OFDM witness run the raw
 code stayed at 32–33 against baseline 32 across 650 submitted frames; 636 were
-captured with valid FCS across all five requested rates. A separate
-transition-churn run submitted 1,000/1,000 frames through 118 CCK/OFDM TSSI
-table changes; the witness captured 660 canonical frames across both rates,
-all with valid FCS, while the same 32–33 thermal range held.
+captured with valid FCS across all five requested rates. A separate 1,000-frame
+run alternating CCK and OFDM submitted 1,000/1,000; the witness captured 660
+canonical frames across both rates, all with valid FCS, while the same 32–33
+thermal range held. Both runs are rate-coverage and thermal evidence only —
+neither says anything about TX-power tracking, and at these deltas (+0 to +1)
+the two thermal-compensation curves are the same bits anyway.
 
 ## TX power control
 

src/rtl8733b/CLAUDE.md

@@ -138,9 +138,11 @@ loudly — without tearing the session down, since an unported optional knob is
 not a hardware-safety event — while `false` succeeds as a no-op because that is
 the state MAC bring-up already leaves programmed.
 
-`DeviceConfig::tuning::disable_cca` cannot be honoured either, and `InitWrite`
+`DeviceConfig::tuning::disable_cca` cannot be honoured either, and bring-up
 warns rather than dropping it — a config knob must not be the one door where a
-request the setter refuses loudly instead vanishes without a word.
+request the setter refuses loudly instead vanishes without a word. The warning
+sits in `bring_up_to_phy`, not `InitWrite`, so an RX-only session that set the
+knob is told too, and so it fires exactly once per bring-up.
 
 ## Validation status
 

src/rtl8733b/Rtl8733bDevice.cpp

@@ -150,7 +150,6 @@ void Rtl8733bDevice::InitWrite(SelectedChannel channel) {
 
 bool Rtl8733bDevice::configure_tx_power(SelectedChannel channel) {
   _tssi_tracking = false;
-  _tssi_cck = false;
   /* Closed-loop TSSI is the TX-power control on a TSSI-offset PG unit, so it
    * is not optional there: the flat fallback index below is a conservative
    * bring-up value, and on-air it runs cold enough that HT rates do not
@@ -171,7 +170,16 @@ bool Rtl8733bDevice::configure_tx_power(SelectedChannel channel) {
    * 0..+17 and first differ at +18, while a five-minute max-duty MCS7 soak
    * plateaued at +8 after two minutes and stopped climbing. It is set from the
    * rate class anyway because that costs nothing and is what the vendor does —
-   * but do not expect it to be measurable. */
+   * but do not expect it to be measurable.
+   *
+   * Which is just as well, because this is weaker than the vendor's keying in
+   * the canonical demo flow: txdemo calls InitWrite before SetTxMode, so
+   * _tx_mode_default is usually unset here and the OFDM/HT table is what a
+   * DEVOURER_TX_RATE=1M session loads — the CCK branch is reached only by a
+   * caller that configures the mode first, or by a later SetMonitorChannel.
+   * The vendor keys on the rate in flight at setup instead. Nothing chases
+   * that gap, because closing it would buy a table identical to the one
+   * already loaded at every delta this part reaches. */
   const bool cck_table = _tx_mode_default.has_value() &&
                          _tx_mode_default->mode ==
                              devourer::TxMode::Mode::Legacy &&
@@ -184,7 +192,6 @@ bool Rtl8733bDevice::configure_tx_power(SelectedChannel channel) {
           channel, _efuse, rtl8733b::kSafeTssiTargetQdbm8733b))
     return false;
   _tssi_tracking = true;
-  _tssi_cck = cck_table;
   return true;
 }
 
@@ -591,7 +598,6 @@ void Rtl8733bDevice::Stop() {
     }
     _tssi_tracking = false;
   }
-  _tssi_cck = false;
   _phy_ready = false;
   if (_mac_ready) {
     _mac.stop();

src/rtl8733b/Rtl8733bDevice.h

@@ -69,7 +69,6 @@ class Rtl8733bDevice : public IRtlDevice {
   bool _phy_ready = false;
   bool _tx_ready = false;
   bool _tssi_tracking = false;
-  bool _tssi_cck = false;
   std::atomic<bool> _rx_stop{false};
   std::atomic<bool> _rx_active{false};
   std::atomic<uint8_t> _rx_configured_bw{0};