docs: record idle power ladder, trigger counters, and scrolling Diag screen

CHANGELOG [Unreleased]:
- Added: OLED idle power ladder (breathing dot @ 2 min, full off @ 15 min).
- Added: host02 / trig / tx trigger-flow counters for issue #3 triage.
- Added: D-pad scrolling Diagnostics screen.
- Changed: flush_fb split into flush_fb_raw + chrome wrapper.
- Changed: Diagnostics row order re-prioritized for trigger triage.

README — replace stale "auto-dim after 5 min idle" line with the
new three-stage power ladder description.

CLAUDE.md — new "Idle power ladder" paragraph in the Architecture
section (state machine + wake events + why contrast-register dim
doesn't work on this panel), and a new entry in "Where features
live" for adding diagnostic rows.

There's a stray older `[Unreleased]` heading at CHANGELOG.md:112
that looks like leftover release content (speaker/haptic regression
fix + Audio Auto Haptics) which actually shipped in an earlier tag.
Not touched here; flagging for a future CHANGELOG hygiene pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CHANGELOG.md

@@ -8,6 +8,17 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/). Version
 
 ## [Unreleased]
 
+### Added
+
+- **OLED idle power ladder.** Replaces the single-tier 5-min auto-dim with a three-stage state machine: at 2 min idle the panel wipes black and a 2×2 "breathing dot" (1 s on / 1 s off) walks through 8 evenly-spaced positions every 30 s; at 15 min idle the SH1107 is sent `cmd(0xAE)` (display off) entirely. Wakes instantly on KEY0/KEY1, controller pair (BT-connect rising edge), or any input-report change. Why this shape: on the Waveshare panel, bench-testing `kDimContrast = 0x10` and `0x02` both produced only ~10 % perceptual reduction (SH1107's contrast register vs apparent brightness is heavily non-linear on this hardware), so the only reliable per-pixel dim available is *rendering fewer pixels*. The breathing dot lights ~4 of 8 192 pixels half the time — roughly a 1 000× drop in cumulative current — while still indicating "the dongle is alive," and the rotating position spreads OLED wear across the panel.
+- **Trigger-flow diagnostic counters on the Diagnostics screen.** `host02` (total `0x02` HID OUT reports from host) / `trig` (those where the host set `AllowRight|LeftTriggerFFB` in `valid_flag0`) / `tx` (forwarded as BT `0x31` sub-`0x10`). Added in response to issue #3 ("trigger tension missing in Death Stranding 2"). Lets the user triage in one game session whether the dongle, the host driver, or the controller is the source of the missing adaptive-trigger effect — without a UART or BT sniffer.
+- **Diagnostics screen now scrolls with the controller D-pad.** Refactored to a row-list (10 rows currently: Uptime / BT state / host02 / trig+tx / BT31 in/s / USB aud/s / BT32 out/s / Mic in/s / Mic dec=&w= / Mic prefix). 5 rows visible at a time; ▲/▼ glyphs at the right edge mark "more above/below." Read-only — no cursor, unlike Settings, since there's nothing to select.
+
+### Changed
+
+- **`flush_fb()` split.** Internal refactor: `flush_fb_raw()` writes just the framebuffer; `flush_fb()` is now `draw_button_chrome() + flush_fb_raw()`. Lets the dim-tier renderer push the breathing dot without the K0/K1 chrome arrows (no navigation target while the panel is asleep).
+- **Diagnostics row order re-prioritized.** The first 5 rows (always visible without scrolling) cover the most common triage path: Uptime / BT state / `host02` / `trig`+`tx` / `BT31 in/s`. Audio + parked-mic-investigation counters live below the fold.
+
 ---
 
 ## [0.6.3-oled-edition] — 2026-05-18

CLAUDE.md

@@ -66,6 +66,8 @@ The development cadence is **one feature per UF2 + checkpoint with the user befo
 
 **OLED add-on is optional and self-contained:** All 10 screens, the SH1107 SPI driver, the 5×7 font, the icon table, and the input handling live in `src/oled.cpp` (~30 KB). The only outward dependencies are read-only accessors (`bt_is_connected`, `bt_get_addr`, `audio_peak_*`, `bt_get_signal_strength`, the new slot accessors) and the global `interrupt_in_data[63]` (read-only for input visualization). When no OLED is wired, the SPI writes go nowhere — no init check needed.
 
+**Idle power ladder (`oled_loop` tail):** Three-stage state machine (`OLED_ACTIVE` → `OLED_DIM` → `OLED_OFF`) driven by `last_activity_us`. `kAutoDimUs = 2 min` enters Dim — the regular per-screen render is replaced with `render_dim_pulse()`, which clears the framebuffer and walks a 2×2 dot through 8 positions every 30 s, blinking 1 s on / 1 s off. `kAutoOffUs = 15 min` enters Off — `cmd(0xAE)` puts the SH1107 to sleep and `oled_loop` returns early before rendering. Wakes on KEY0/KEY1 (via `handle_buttons` bumping `last_activity_us`), `bt_is_connected()` rising edge, or any change in the `interrupt_in_data[0..9]` hash. The dim tier uses `flush_fb_raw()` (the chrome-less variant) since there's no nav target while asleep. **Why this shape:** the SH1107 contrast register has a heavily non-linear perceptual curve on the Waveshare panel — even `0x02` looks ~90 % as bright as `0xFF`. The only reliable "dim" available is rendering fewer pixels.
+
 **Multi-slot pairing (Phase G):** Storage is two-tier:
 
 - **Link keys** stay in BTstack's TLV NVM (4 slots, unchanged from upstream).
@@ -136,6 +138,7 @@ When asked to modify behavior, the *first* file to read is usually one of:
 
 - New BT pairing / connection state behavior → `src/bt.cpp` (HCI + L2CAP event handlers).
 - New OLED screen or change to existing one → `src/oled.cpp`.
+- New diagnostic counter on the OLED Diagnostics screen → bump `kNumDiagRows` in `src/oled.cpp` and add a `case` to `format_diag_row()` (single switch, one row per case). The screen scrolls automatically; no D-pad wiring needed. Counters that need rate-per-second arithmetic should be sampled in `sample_diag_rates()` and read from `g_diag_rates`. Counter globals themselves typically live in `src/main.cpp` next to `g_bt_31_packets` etc. with `extern` declarations near the top of `src/oled.cpp`.
 - New persistent config field → `src/config.h` (struct), `src/config.cpp:config_valid()` (defaults + clamping), `src/oled.cpp:format_settings_item()` (UI), `src/oled.cpp:settings_adjust()` (D-pad ▶◀ behavior). Update `CHANGELOG.md`.
 - USB descriptor or interface change → `src/usb_descriptors.cpp` + `src/tusb_config.h`.
 - Audio / haptic path → `src/audio.cpp`. **Don't** add stack arrays sized smaller than the resampler / Opus expects (this is the C1 bug that caused the long-standing "audio stuttering" issue — fix landed in upstream `5b04cbd`, but the lesson stands).

README.md

@@ -46,7 +46,7 @@ This project enables the Raspberry Pi Pico2W to function as a Bluetooth bridge f
 - **4-slot persistent multi-controller pairing** — bond up to four DualSenses, switch between them from the OLED, slot 0 reconnects automatically on boot
 - **Lightbar color picker** with 4 user favorite slots + breathing / rainbow / fade effect presets
 - **Persistent settings menu** for the 8 firmware config fields (haptics gain, speaker volume, polling rate, etc.) with hold-to-confirm Reset and Wipe-all-slots actions
-- **OLED brightness control + auto-dim** after 5 min idle (extends OLED life)
+- **OLED idle power ladder** — manual brightness cycle (KEY1 long-press), automatic deep-dim with a small breathing dot at 2 min idle, full display-off at 15 min idle. Wakes instantly on button, controller pair, or input. Real burn-in protection, not just a contrast tweak.
 - **Soft-reboot** without unplugging USB via DS5 `PS + Mute` hold (works headless) or **KEY0 + KEY1 held together for 1 s** on the OLED add-on (replaces the older KEY0 double-click gesture, which was easy to fire by accident while paging quickly)
 - **Audit pass on the core bridge** — critical stack-overflow fix in the audio path (resolves long-standing "audio stuttering"), security hardening, watchdog, length validation across HID/L2CAP boundaries (see [CHANGELOG.md](./CHANGELOG.md))