MeshCore-Solo/FEATURES.md

# Feature roadmap

Joystick-only UX constraints: 4 directions + Enter + Back. No text entry except inside KeyboardWidget. Everything else navigable with cursor + press.

Status legend: 📋 planned · 🚧 in progress · ✅ done · ❌ rejected/deferred

---

## Priority queue

### ✅ Mark-all-read at type level

Hold Enter on the MESSAGE mode-select screen (DM / Channels / Rooms) opens a 1-item context menu "Mark all read". Acts on the currently highlighted mode and shows a brief confirmation alert.

Implementation:
- New `UITask::clearAllDMUnread()` — `memset` over `_dm_unread_table`
- `QuickMsgScreen::clearAllChannelUnread()` already existed
- `UITask::clearRoomUnread()` already existed
- Title is a `static const char*` table (PopupMenu stores the title pointer verbatim — locals would dangle)
- Zero schema impact, all counters live in RAM

### ✅ Favourites dial

Phase 1 ✅ (storage + read-only render + grid nav)
Phase 2 ✅ (pin from Contact options menu in QuickMsg + slot picker submenu)
  - Enter on a filled tile opens that contact's DM directly
  - Cancel from a Favourites-opened DM returns to the home screen
Phase 3 ✅ (in-place pin picker on empty tile: upstream-favourited contacts first,
   then recent DM contacts deduped; selecting a contact that's already pinned
   elsewhere moves it to the new slot)

**Follow-up done**: OLED unread-badge overlap fixed — badge and name share the
same baseline, drawTextEllipsized's max width subtracts badge width + a 3 px
gap so names shorten to "Nam…" before the digit.

A 2×3 grid (six slots) of pinned contacts on its own home page, between Clock and Messages. Joystick picks a tile, Enter opens the existing DM conversation or sends a pre-set quick reply.

Data model:
- New field in NodePrefs: `uint8_t favourite_contacts[6][6]` — first 6 bytes of each contact's `pub_key` (enough to disambiguate locally)
- Lookup at render time: walk contacts, match prefix, render name + unread badge
- Empty slot renders as "+" placeholder; Enter on empty opens a contact picker (existing UI)

Pinning UX:
- In QuickMsg DM list, long-press on a contact → context menu → "Pin to dial" → asks which of the 6 slots
- Unpin via the same menu (only shown when contact is already pinned)

Schema bump: add `favourite_contacts` to NodePrefs, bump `SCHEMA_SENTINEL` low byte.

Render layout (250×122 landscape e-ink):
```
╔══════════════════════════════╗
║ Favourites                   ║
╠══════════════════════════════╣
║ ┌──────┐ ┌──────┐ ┌──────┐   ║
║ │Alice │ │Bob 3 │ │  +   │   ║
║ └──────┘ └──────┘ └──────┘   ║
║ ┌──────┐ ┌──────┐ ┌──────┐   ║
║ │Carol │ │  +   │ │  +   │   ║
║ └──────┘ └──────┘ └──────┘   ║
╚══════════════════════════════╝
```

Joystick navigation is natural with 6 tiles (UP/DOWN between rows, LEFT/RIGHT within row).

### 🚧 GPS trail (renamed from breadcrumb)

Phase 1 ✅ (storage + sampling + Summary view + G indicator in status bar)
Phase 2 ✅ (auto-fit Map view with cos(lat) aspect compensation; LEFT/RIGHT cycles views)
  - Summary scrolls on short panels (OLED) so hint stops overlapping
  - Status-bar G blinks at the same cadence as A (forces 1 s home refresh)
  - Default sampling 30 s + 5 m min-delta (was 60 s + 25 m — too sparse on foot)
  - "Avg speed" replaces "Speed"; Time uses RTC so it ticks every render
  - Stop → start creates a new segment; the map doesn't bridge dead time,
    and total distance skips segment boundaries
Phase 3 ✅ (per-point list view with HH:MM local time + delta-from-previous;
   segment-start rows show "start" instead of a delta)
Phase 4 ✅ (Hold-Enter popup grows Save / Load / Reset / Export GPX /
   Export saved entries. Single flash slot at /trail (binary header with
   magic+version+count+accumulated_ms then raw TrailPoint records). GPX 1.1
   dump goes over USB Serial; "Export GPX" streams the live RAM ring,
   "Export saved" streams the flash file straight to USB without touching
   the live ring. Segments respect SEG_START boundaries. Alert reflects
   BLE-app-collision state)
Phase 5 ✅ (Settings + actions consolidated into a single Hold-Enter popup —
   Min dist + Units cycled with LEFT/RIGHT (popup stays open), plus
   Start/Stop tracking and Reset action items. Short Enter never toggles —
   both start and stop go through the popup, so a stray tap can never change
   tracking state. View counter (N/3) lives in the title bar; the bottom hint
   row is gone, content fills the freed space. Sampling cadence fixed at 1 s,
   GPS upd setting also removed; both rely on the sensor manager's defaults)
Polish ✅ (map view: filled/open dot markers around segment breaks;
   "Waiting for GPS fix" status when started without a lock;
   capacity bumped to 512 points; elapsed/avg-speed run on millis() instead
   of RTC so they tick even before GPS time is synced)

Tools › Breadcrumb. Periodically samples `(lat, lon, ts)` into a RAM ring buffer; user explicitly saves snapshots to flash.

**Logging is a runtime state**, not a settings value. User starts/stops from the
Tools › Breadcrumb screen. Once active, sampling continues in the background
regardless of which screen is shown, and a `G` indicator appears in the status
bar (analogous to `A` for auto-advert). A reboot resets the active state to
off; the RAM trail is also lost on reboot unless saved to a flash slot first.

Settings only control sampling cadence and the min-distance gate — they don't
enable/disable the feature.

**Storage model — RAM ring with explicit save**

Rationale: auto-off only blanks the display, the firmware keeps running, so the RAM trail survives every idle scenario. Typical use is a single trip start→stop while wearing the device; persisting across reboots is rarely wanted. RAM-only avoids ~1400 flash writes/day and the LittleFS wear that comes with continuous logging.

- Live ring: `BreadcrumbEntry[BC_RAM_CAP]` in `UITask` (or a dedicated component). Each entry `int32_t lat_1e6, int32_t lon_1e6, uint32_t ts` = 12 B. Cap = 256 → 3 KB RAM. nRF52840 (256 KB RAM) has plenty of headroom.
- Wrap-on-write: oldest entry replaced when buffer full.
- Reboot wipes the live trail (intentional; matches the "this trip" model).

**Snapshot slots on flash** (user-initiated only):
- `/breadcrumb.0`, `/breadcrumb.1`, `/breadcrumb.2` — three named slots
- Each file: small header (count, start_ts, end_ts, total_distance_m) + entry array
- Written only on explicit "Save trail" action — zero background writes, zero wear concern
- Optional: auto-save to slot 0 on detected low-battery shutdown (single write before going dark)

UI screens (LEFT/RIGHT cycles):
1. **Summary** — total distance (km), elapsed time (h:mm), point count, current speed (from last 2 samples), GPS fix indicator
2. **Trail map** — ASCII bounding-box plot. Auto-fit the polygon, current position marked `X`, start marked `*`. UP/DOWN zoom, LEFT/RIGHT pan when zoomed.
3. **Last N entries list** — scroll through recent points with timestamp + delta from previous.

Joystick actions:
- Enter → toggle live logging on/off (status bar shows `*` when active, like auto-advert `A`)
- Back → exit
- Hold Enter → context menu:
  - "Reset trail" — clear RAM ring
  - "Save trail → slot N" — snapshot RAM into chosen flash slot
  - "Load trail ← slot N" — restore from chosen slot into RAM ring
  - "Export over USB" — dump live RAM trail as KML/GPX over serial

Statistics computed on the fly walking the ring:
- Total distance: sum of Haversine(p[i], p[i-1])
- Elapsed time: ts[last] - ts[first]
- Current speed: dist(last, prev) / (ts[last] - ts[prev])

Settings:
- Settings › GPS › Breadcrumb interval: 30 s / 1 min / 5 min / 15 min (default 1 min) — only the cadence; logging on/off is a Tools toggle
- Settings › GPS › Breadcrumb min delta: 5 m / 25 m / 100 m (skip near-stationary samples to keep the ring densely populated with real movement)
- Export format: GPX (standard for GPS tracks; OSMAnd / Garmin compatible)

Schema impact: new prefs fields `uint8_t breadcrumb_interval_idx`, `uint8_t breadcrumb_min_delta_idx`. Sentinel bump. The slot files are separate from prefs.

Edge cases:
- No GPS fix: skip sampling, status indicator dims
- Low-batt shutdown: optional auto-save to slot 0 (one write) before powerdown
- Memory: 3 KB RAM is negligible on this MCU; if RAM ever tightens, drop to 128 entries

---

## Backlog (not yet prioritised)

### Waypoints — mark a spot, navigate back ⭐ (next candidate)

Turns Solo from a comms device into a basic GPS navigator. Mark the current
position with a short label, then later get bearing + distance back to it —
ideal for off-grid use (car, camp, trailhead, water source).

**Storage** — dedicated flash file `/waypoints` (separate from prefs, like
`/trail`). Fixed table, no schema-sentinel impact:

```
struct Waypoint {
  int32_t  lat_1e6, lon_1e6;   // saved fix
  uint32_t ts;                 // when marked (RTC)
  char     label[12];          // short name, NUL-terminated ("CAR", "CAMP", "H2O"…)
};
static const int WAYPOINT_MAX = 16;   // 16 × 24 B = 384 B file
```

**Marking** — from the GPS or Trail screen: Hold Enter → "Mark here".
- Requires a GPS fix; otherwise alert "No GPS fix".
- Opens the existing `KeyboardWidget` to type the label (≤11 chars). Empty
  input auto-labels `WP<n>`.
- Saves the current fix + label, appends to the file.

**Visible on the trail Map** — waypoints render on the existing Map view as a
distinct marker (e.g. a hollow diamond or a small flag) so they show in
context with the recorded track:
- Fold waypoint coords into the map's bounding box so off-track waypoints
  stay in frame. Today `renderMap()` derives the box from
  `TrailStore::boundingBox()`; extend it to also span the waypoint table
  (and handle the "waypoints but empty trail" case — map still renders).
- Generalise the `project()` lambda to take raw (lat, lon) instead of a
  `TrailPoint&` so the same projection draws both track points and waypoints.
- Marker shows the label's first character beside it when there's room
  (122 px is tight with many waypoints); the full label lives in the list /
  nav view.

**Trail workflow integration** — waypoints live *inside* the Trail screen, not
a separate Tools entry, because marking points of interest happens while you
are recording:
- **Mark**: Trail → Hold Enter → "Mark here" (new action-menu row). Opens the
  keyboard for the label, saves the current fix. Works whether or not tracking
  is active — a waypoint is independent of trail recording state.
- **Manage / navigate**: Trail → Hold Enter → "Waypoints" → a PopupMenu list
  of saved waypoints (label + distance). Selecting one:
    - Enter → fullscreen nav (see below).
    - Hold Enter → Rename / Delete (later: **Share over mesh**).
- Waypoints persist across trail Reset / reboot (separate `/waypoints` file),
  unlike the RAM trail ring.

**Navigation view — two bearings, no compass needed**

The L1 has no magnetometer, so we can't show "you are facing X". Instead the
nav view shows two *absolute* bearings and lets the user do the comparison —
robust against GPS jitter, no relative-turn maths:

```
   CAMP            ← waypoint label
   1.4 km          ← distance to target
   To:  145° SE    ← absolute bearing target-from-me (haversine/bearingDeg)
   Hdg: 090° E     ← my course over ground, derived from recent GPS movement
```

Reading it: target is at 145°, I'm travelling at 90° → I need to bear right.
When standing still (course undefined) the Hdg line shows `--` instead of a
stale value.

**Course over ground (COG)** — a small `TrailStore` helper:
`bool currentCourse(int& deg)` walks back from the newest fix until the
cumulative distance from it exceeds a threshold (~10–15 m so GPS noise
doesn't dominate) and returns the bearing from that older fix to the newest.
Returns false (→ `--`) when there isn't enough recent movement. Refreshed ~1 s.
`bearingDeg` / `bearingCardinal` are currently private statics in NearbyScreen;
lift them into a shared header (or TrailStore) so both screens use them.

This COG value can later back a standalone "heading" trail view if wanted, but
the two-bearing nav view already covers the practical need.

**Shared nav view — also navigate to a node** ⭐

The nav view's target is just `(lat, lon, label)` — it doesn't care whether
that came from a waypoint, the trail start (Backtrack), or a node's
last-known advert position. Make it a small reusable component
(`NavView` / `drawNavTo(display, target_lat, target_lon, label)`) and wire it
in from **Nearby Nodes** too: node detail → "Navigate" → same To/Hdg/distance
screen, retargeting the selected node. This folds the backlog "Compass to
contact" idea into one screen and means Nearby stops being a static snapshot —
you can actually walk toward a person.

Node target is the contact's `gps_lat/gps_lon` from its last advert (already
read in NearbyScreen). It's a *last-known* fix, not live, so the label could
show the advert age (e.g. `Alice (5m)`); pair it with Auto-Advert on the other
device for a moving target.

**COG source must be decoupled from trail recording.** Deriving the heading
from `TrailStore` only works while a trail is actively being recorded — but
node/waypoint navigation shouldn't require the user to start trail logging.
Fix: a tiny independent COG ring in UITask (≈4 fixes), maintained on every GPS
poll regardless of trail state. The trail ring stays a separate concern, so
the Hdg line is available everywhere (waypoints, nodes, backtrack).

The COG ring is **time-sampled with guards**, not raw displacement-gated:
push every GPS fix at the normal poll cadence (~1 s) into a short rolling
window (a few seconds of fixes), and compute the heading as the bearing
across the window (oldest→newest), optionally low-pass smoothed. Time-based
sampling gives a steadier, averaged course than bearing between just two
points, and tracks slow movement without lagging.

Two guards keep it honest:
- **Gross-error rejection** — drop a fix before it enters the window if it
  implies an impossible jump (implied speed over a sane cap, e.g. > ~50 m/s
  between consecutive fixes), or if the provider exposes a usable
  validity/HDOP signal. One bad fix shouldn't swing the heading.
- **Minimum displacement over the window** — only emit a heading once the
  total movement across the window exceeds a small threshold (a few m). Below
  that the user is effectively stationary: hold the last good heading, and
  show `--` until the window has cleared the threshold at least once. This
  is what stops a standing user from getting a spinning bearing.

Threshold(s) can be fixed constants to start; expose in Settings later if it
proves worth tuning.

Open question: whether the nav view should also be reachable as a 4th Map
overlay state (cycle a "highlighted" waypoint with LEFT/RIGHT on the Map) or
stay list-driven only. Start list-driven; add map cycling later if wanted.

### Backtrack — navigate home along the recorded trail

Pairs with Waypoints but needs zero new storage: read the live `TrailStore`
ring and show bearing + distance back to the trail start (or the nearest
recorded point). "Get me back to where I started." A Trail action-menu entry
"Navigate to start" opens the same fullscreen nav view as Waypoints.

### Compass to contact — folded into the Waypoints nav view

Superseded by the shared nav view described under **Waypoints** above:
navigate to a node = open that nav view with the contact's last-advert
`gps_lat/gps_lon` as the target. No separate compass screen needed; the
"two absolute bearings (To / Hdg)" approach replaces the relative-heading
arrow this entry originally assumed. Kept here only as a cross-reference.

### SOS broadcast

Configurable in Settings › System › SOS:
- Target: channel index or DM contact
- Message template (uses placeholders)

Trigger: Hold Back + Hold Enter for 3 s on any screen → confirmation popup ("Send SOS?") → Enter to send. Sends with `{loc}` and `{batt}` filled. 30 s cooldown.

### Range test

Tools › Range Test:
- Pick a node from contacts/nearby
- Enter starts pinging every 5 s, logs RTT + RSSI + SNR (ring ~30)
- Display shows current values + 30-sample sparkline (block characters)
- Enter stops; Hold Enter for context menu (reset, change target)

### Quiet hours

Settings › Sound › Quiet Hours:
- Enable on/off
- Start HH (LEFT/RIGHT to change, 24 h)
- End HH

When within window: buzzer set to "off" (overrides setting), display brightness → 0. Restores prefs values when window ends. Time source: rtc_clock.

### Channel scanner home page

Toggleable in Settings › Home Pages. Lists channels with: name, unread count, last message age. Enter opens the channel. Sort by recency by default; LEFT/RIGHT toggles to alphabetical.

### Contact distance sort

QuickMsg DM list: a 4-th sort mode (currently sorted by message count). LEFT/RIGHT on the list header cycles: name | message-count | recency | distance. Distance uses GPS pos from contact's last advert.

### Signal stats screen

Tools › Stats:
- Battery voltage 60-min sparkline
- RSSI of last 30 received packets
- Noise floor current
- Free heap (if available)

Read-only. UP/DOWN switches between metrics. Bottom shows current value as text.

### Auto-reply trigger words with sensor placeholders

Bot already has a single trigger word. Extend to a small table of (trigger, reply-with-placeholder) pairs:
- "temp?" → replies with `{temp}`
- "loc?" → replies with `{loc}`
- "batt?" → replies with `{batt}`

Stored in NodePrefs as fixed-size table (say 4 pairs × 16 B). UI: edit pairs in Tools › Auto-Reply Bot.

### Lock-screen unread count

Show `12 new` or two-line `5 DM / 7 ch` on lock screen below the time. Reuses existing `_hist`/`_dm_hist` unread counters. Cosmetic only, no schema change.

### Power profile presets

Settings › Profile: Indoor / Outdoor / Expedition. Each pre-fills:
- Auto-off seconds
- GPS interval
- Auto-advert interval
- Brightness

Single Enter applies. Stored as `uint8_t profile_idx` with hardcoded value tables.

### Battery curve calibration

Settings › System › Batt Calibration: edit 5 voltage breakpoints used to convert mV → %. UP/DOWN selects breakpoint, LEFT/RIGHT changes voltage in 50 mV steps. Helps users with non-standard LiPos report accurate %.

### Mark-read at type level — already covered above as priority

### Display test pattern

Tools › Display Test: full-screen grid + bars + Lemon glyph dump. Useful for verifying driver/font changes after flashing.

### Group "who's online" ping

From channel view, Hold Enter → "Who's online?". Sends 0-hop discovery to channel members, collects responses for 10 s, shows a list with RSSI. Similar to existing Nearby active discovery but scoped to a channel.

---

## Deferred

### ❌ Morse keyboard

Cute but niche. Skip unless explicitly requested.

### ❌ Buzzer EVENTS_STOPPED IRQ chaining

Marginal real-world gain (2 ms between notes during melody playback only), high risk on the PWM peripheral.

### ❌ Vibration feedback

Wio Tracker L1 doesn't have a haptic motor. N/A.

---

## Implementation order suggestion

1. **Mark-all-read** — smallest patch, biggest day-to-day comfort gain
2. **Favourites dial** — new home page + new prefs field; touches familiar areas (QuickMsg context menu, NodePrefs, schema sentinel bump)
3. **GPS breadcrumb** — largest of the three; introduces a new flash file and a Tools sub-screen with multiple views

After #3, re-prioritise the backlog with the user.

---

# Code audit — known bugs / hardening backlog

Pass through wio-unified after commit `321d769e`. Grouped by severity. Listed but **not yet fixed**.

## Critical

### ✅ `onChannelMessageRecv` / `onChannelDataRecv` — guard for `findChannelIdx == -1`

[`MyMesh.cpp:561-602`](examples/companion_radio/MyMesh.cpp#L561-L602), [`MyMesh.cpp:619-625`](examples/companion_radio/MyMesh.cpp#L619-L625)

Both group-channel receive paths now check the result of `findChannelIdx()` before continuing:

```cpp
int idx = findChannelIdx(channel);
if (idx < 0) {
  MESH_DEBUG_PRINTLN("...: unknown channel secret — dropping message");
  return;
}
uint8_t channel_idx = (uint8_t)idx;
```

Unknown-secret packets no longer pollute the offline queue, UI history or trigger the bot with a bogus `idx=255`.

### ✅ `addChannelMsg` guards against bogus index

[`QuickMsgScreen.h:414-433`](examples/companion_radio/ui-new/QuickMsgScreen.h#L414-L433)

Defensive `if (ch_idx >= MAX_GROUP_CHANNELS) return;` at function entry — prevents ring-buffer pollution in case any future caller forgets the upstream guard. With C1 fixed this should never trigger, but the cost is zero.

## High

### 📋 `findChannelIdx` scans all-zero secret in uninitialised slots

[`BaseChatMesh.cpp:892-897`](src/helpers/BaseChatMesh.cpp#L892-L897)

```cpp
for (int i = 0; i < MAX_GROUP_CHANNELS; i++) {  // full range, not num_channels
  if (memcmp(ch.secret, channels[i].channel.secret, 32) == 0) return i;
}
```

If `ch.secret` is all-zero (uninitialised or corrupted) and an unused slot is also all-zero, the function returns that unused slot as a "match". Upstream code — needs upstream fix or local override.

### 📋 `saveChannels` writes all 40 slots to `/channels2`

[`DataStore.cpp:563-580`](examples/companion_radio/DataStore.cpp#L563-L580) + [`BaseChatMesh.cpp:871-877`](src/helpers/BaseChatMesh.cpp#L871-L877)

`saveChannels` calls `getChannelForSave(idx, ch)` in a loop; `BaseChatMesh::getChannel(idx)` returns `true` for any `idx < MAX_GROUP_CHANNELS` (including uninitialised slots). Result: file is always ~2.7 KB (40 × 68 B). The `loadChannels` sanity check (skip empty secret) papers over the symptom but the root cause is in save.

### 📋 `msgRead(0)` wipes the whole DM unread table

[`UITask.cpp:1403-1410`](examples/companion_radio/ui-new/UITask.cpp#L1403-L1410)

```cpp
if (msgcount == 0) {
    memset(_dm_unread_table, 0, sizeof(_dm_unread_table));
    ((QuickMsgScreen*)quick_msg)->clearAllChannelUnread();
}
```

When the companion app reads the last message from the offline queue, all on-device badges disappear. Previously discussed and a fix was reverted as "intended sync behaviour" — keep as known limitation; document or restrict to "Favourites Dial badges only".

### ✅ `loadPrefsInt` scopes `trail_units_idx` reset to the 0xC0DE0003 jump

[`DataStore.cpp:326-343`](examples/companion_radio/DataStore.cpp#L326-L343)

The reset is now gated on `sentinel == 0xC0DE0003` so newer mismatches (e.g. 0xC0DE0004 → 0xC0DE0005, which both saved the field correctly) no longer clobber the user's choice.

## Medium

### ❌ `CMD_SET_DEFAULT_FLOOD_SCOPE` off-by-one — not a bug

[`MyMesh.cpp:2143`](examples/companion_radio/MyMesh.cpp#L2143)

Re-checked: `default_scope_name` is declared `char[31]` (not 32), so `n < 31` correctly admits the maximum 30-character string + NUL. The audit entry was a misread.

### ✅ `strlen` on `cmd_frame` without null-termination — replaced with `strnlen`

[`MyMesh.cpp:2140-2147`](examples/companion_radio/MyMesh.cpp#L2140-L2147)

The 31-byte name slot in `CMD_SET_DEFAULT_FLOOD_SCOPE` doesn't have to be NUL-terminated by the sender. Switched to `strnlen(…, 31)` so the search can't run past the field into the 16-byte key (or beyond the frame).

### 📋 `PopupMenu._cap` updated only in `render()`

[`PopupMenu.h:37-44, 77-90`](examples/companion_radio/ui-new/PopupMenu.h#L37-L90)

Left as-is: the framework always renders before forwarding input, so the fragile invariant doesn't fire in practice. Worth a refactor only if the call order ever changes.

### ✅ `renderDiscoverDetail` guarded against narrow displays

[`NearbyScreen.h:325-348`](examples/companion_radio/ui-new/NearbyScreen.h#L325-L348)

Pub-key line is now skipped entirely when `max_chars < 4` instead of feeding a negative length to `strncpy`.

### 📋 `expandMsg` GPS validity test treats (0, 0) as invalid

[`MyMeshBot.h:23, 60`](examples/companion_radio/MyMeshBot.h#L23)

```cpp
sensors.node_lat != 0.0 || sensors.node_lon != 0.0  // proxy for "valid GPS"
```

Point (0, 0) is a legitimate location (Gulf of Guinea). Corner case but a logic error. Left for a future pass with a proper GPS-validity bool.

## Low

### ✅ SNR division by 4 — now uses `%.1f`

[`NearbyScreen.h:355-357, 487`](examples/companion_radio/ui-new/NearbyScreen.h#L355-L487)

Detail view (`SNR: %.1f dB`, `Rem: %.1f dB`) and discover list cards (`SNR:%.1f`) both keep the 0.25 dB resolution. Stays consistent with the ping popup, which already used `%.1f`.

### 📋 Trail `_count` cast to `uint16_t`

[`Trail.h:176`](examples/companion_radio/Trail.h#L176)

Safe today (CAPACITY=512 fits), fragile if CAPACITY grows past 65535.

### 📋 Bot `strstr` on truncated 199-char buffer

[`MyMeshBot.h:14-17`](examples/companion_radio/MyMeshBot.h#L14-L17)

Trigger word near the end of a >199-character message will not match.

### ✅ `strncpy("?", buf, sizeof(buf))` replaced with `strcpy`

[`QuickMsgScreen.h:785, 858`](examples/companion_radio/ui-new/QuickMsgScreen.h#L785)

Two fallback "?" sender names now use a plain `strcpy` so we don't memset 21 unused bytes for a one-character string.

### 📋 Title truncation in MSG_PICK reply mode

[`QuickMsgScreen.h:937`](examples/companion_radio/ui-new/QuickMsgScreen.h#L937)

`char title[24]` for `"RE:" + nick[32]` truncates long nicks silently.

## Priority for merge

Fix status after this pass:

- ✅ C1 + C2 — `findChannelIdx == -1` guarded at both channel-recv paths; `addChannelMsg` defends against bogus index
- ✅ H4 — `trail_units_idx` reset scoped to the 0xC0DE0003 jump
- ✅ M2 — `strnlen` instead of `strlen` on default scope name
- ✅ M4 — `renderDiscoverDetail` skips pub-key line on very narrow displays
- ✅ L1 — SNR shown with 0.25 dB precision everywhere
- ✅ L4 — fallback `"?"` sender no longer memsets through `strncpy`
- ✅ Trail map grid silent loss — when a very elongated trail makes `lat_n` or `lon_n` exceed 40, the renderer now bumps the step up instead of dropping the grid entirely. Comment fixed to match the `/ 3.0f` divisor ("~3 intervals", not 4). [`TrailScreen.h:505-565`](examples/companion_radio/ui-new/TrailScreen.h#L505-L565)
- ❌ M1 — re-checked, not a bug (`default_scope_name[31]`)
- 📋 H1 + H2 — still open; need coordinated fix in upstream `BaseChatMesh` (`findChannelIdx` should iterate `num_channels`, not `MAX_GROUP_CHANNELS`; `saveChannels` should stop at the first uninitialised slot) or a local override
- 📋 H3 — left as known limitation pending UX call
- 📋 M3, M5, L2, L3, L6 — minor or stylistic; left in backlog