docs: Record V1.2.4 in Script A's history and add the release note

Script A: header to V1.2.4 / 2026-10-01; entries for tray_id_stress.sh,
the Script A and Script B hooks, and 6_Blanton_Script_BER_Cycle.ttl,
with notes on the exec bit, the sleep-vs-Interval rule, the hard-coded
BDF, the hostname, the SONiC-only fan setting and the placeholder
password.

CLAUDE.md: status and last release to V1.2.4; the Tray ID stress and the
BER cycle in the overview; a commands block for tray_id_stress.sh; a
gotcha that prbsstat Ber must be read after the first interval is
published, and that Script A / C's own BER (Interval=30, sleep 30) sits
on that edge and has not been verified.

ARCHITECTURE.md: Script A ref and the tag checkbox to V1.2.4; Script 5's
current file name and the new macro 6 in the tree; tray_id_stress.sh in
the tree.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UniUXkxgCG2Ty74advL8Pd

docs/release-notes/v1.2.4.md

@@ -0,0 +1,54 @@
+# v1.2.4 — Tray ID I2C stress in Script A and B, and a Diag / SONiC BER cycle that reads the BER correctly
+
+## ✨ New features
+
+**`tray_id_stress.sh` — Tray ID I2C write / read-back stress**
+* Buses `34` / `35` / `38` / `39`, device `0x70`, register `0x02`. Each bus gets `0xA5` written and read back, then `0x5A` written and read back — the two patterns put every bit in both states.
+* One line per step (`PASS` / `FAIL` / `ERROR`), then a per-bus **Summary** table and a single `Tray ID stress RESULT: PASS|FAIL` line. Exit `0` = all PASS, `1` = any FAIL or I2C error, `2` = bad arguments.
+* `FAIL` (the read worked but returned the wrong value) and `ERROR` (`i2cset` / `i2cget` itself failed) are counted separately, because they point at different faults.
+* The original register value is read first and **written back at the end**, verified by a read. `-R` skips that; `-n N` repeats the whole sequence N times. Buses, address, register and patterns are editable at the top of the file.
+
+**Script A and Script B run it**
+* **Script A** runs one pass after `show_dmesg` as the baseline.
+* **Script B** runs one pass in every soak round, before `sleep 60` — 12 writes per round, registers restored each time.
+
+**`6_Blanton_Script_BER_Cycle.ttl` — Diag ↔ SONiC BER cycle (standalone)**
+* Each cycle measures PRBS BER on unit 0 in the Diag OS, cold-boots into SONiC, measures again, and cold-boots back to Diag. `while 1`, no end. The boot target is picked in the BIOS Boot Manager (`USB Device` = Diag, `Hard Drive` = SONiC).
+* Log: `Logs\Blanton_BER_Cycle_<ts>.log`, timestamps always on.
+
+## 🐛 Bug fixes
+
+**`prbsstat Ber` was read before the first interval had been published — BER read 40–60× low**
+* The BER cycle originally read `prbsstat Ber` 10 s after `prbsstat STArt Interval=30`. Checked against the error counts that `prbs get` reports in the same cycle, that read **Diag ~60× low and SONiC ~40× low**.
+* Moving to `sleep 30` (equal to the interval) fixed SONiC but **not Diag**: its `Ber` goes out 30.15 s after `STArt`, just before the first interval is published. SONiC's `bcmcmd` adds ~0.3 s and just makes it.
+* The macro now uses **`Interval=30` + `sleep 40`**. Over 73 cycles both sides agree with the `prbs get` estimate to within 0.1 decade. The rule: **the sleep must be longer than the interval.**
+
+## 📦 Downloads
+
+| File | Contents |
+|---|---|
+| `Script_ABC_Blanton_V1.2.4.zip` | The full Tera Term working directory, including `Blanton_Script/` to copy onto the DUT |
+
+```bash
+chmod +x ~/Blanton_Script/*.sh
+grep -rlU $'\r' ~/Blanton_Script    # expect no output
+```
+
+## ⚠️ Before you run
+
+* **`chmod +x` after deploying.** Script A and B call `tray_id_stress.sh` by path; without the exec bit every call is `Permission denied` and the round carries on without the check.
+* **Any BER log taken before 2026-09-30 14:13 reads 40–60× low** (BER cycle with `sleep ≤ Interval`). Relative Diag-vs-SONiC trends are usable; absolute values are not.
+* **Script A / C's BER is the same edge case**: `blanton_ber.sh start` (Interval=30) → `sleep 30` → `report`, on SONiC. Whether it catches the first interval has **not been verified**. Lengthening that sleep to 40 is the safe change.
+* **The BER cycle's SONiC → Diag boot writes a hard-coded BDF** (`pcimem /sys/bus/pci/devices/0000:05:00.0/resource0 0x480`). Check the CB FPGA BDF on every unit before running it.
+* **The BER cycle expects the hostname `sonic`.** A unit with another hostname (e.g. `Margin02`) needs `prompt_sonic` / `prompt_sonic_root` edited, or the macro waits forever.
+* **The BER cycle sets the fan to 30 % on the SONiC side only** — SONiC runs ~11 °C hotter than Diag, a variable in any Diag-vs-SONiC comparison.
+* **Its SONiC password is the `YourPaSsWoRd` placeholder**, and it does not read `config.ttl` or `secret/`.
+* **Script 4 has no teardown**: finish it with `blanton_tr518.sh stop` **and** `systemctl stop mlucas-amm`.
+* **`FAN_SPEED` is 100.**
+
+## 🔗 Links
+
+* [ARCHITECTURE.md](https://etgit.et-wen.com/etwen/Blanton_TTL_Script/src/branch/main/ARCHITECTURE.md) — test flow, data models, constraints
+* [CLAUDE.md](https://etgit.et-wen.com/etwen/Blanton_TTL_Script/src/branch/main/CLAUDE.md) — commands and the bench gotchas
+
+**Full changelog:** [V1.2.3...V1.2.4](https://etgit.et-wen.com/etwen/Blanton_TTL_Script/compare/V1.2.3...V1.2.4)