docs(visuals): rebuild the page around the map's Legend card

docs/duplicaterepeaterid.md

@@ -60,9 +60,9 @@ When a new repeater appears on the network with an ID that is indistinguishable
 
 ### 2. Map Appearance
 
-  - **Red Icons**: Both repeaters will appear on the map with **Red** icons (instead of the standard Pink, Orange or Grey).
+  - **Red Chips**: Both repeaters will appear on the map with a **Red** edge on their chip (instead of the usual Green, Pink or Grey). The map legend calls this state **Ambiguous ID**.
   - **Popups**: Clicking on the repeater will show its status as "Duplicate" and will list the repeaters that are in collision with it.
-  - **Pings**: Clicking a grid square on the map that has a repeater involved in an active collision will draw red dashed lines to each repeater in the collision group (and list distance), allowing the viewer to make their own assumption on which repeater was actually involved.
+  - **Pings**: Clicking a grid square on the map that has a repeater involved in an active collision will draw red lines to each repeater in the collision group (and list distance), allowing the viewer to make their own assumption on which repeater was actually involved.
   - **Leaderboards**: Both repeaters are immediately removed from all Leaderboards (Best Repeaters, Max Range, etc.) both on the local region and globally to prevent skewed statistics.
 
 ### 3. Impact on Collected Data
@@ -113,9 +113,9 @@ If both repeaters are active and legitimate (a true collision between two live d
 
 | State | Indicator | Meaning |
 | --- | --- | --- |
-| **Active** | Green / Grey Icon | Normal operation. Unique ID. |
-| **New** | Orange Icon | Recently discovered (less than 14 days old). |
-| **Excluded** | **Red Icon** | **Duplicate ID Detected.** Data from this repeater is currently untrusted. |
+| **Active** | Green Chip Edge | Normal operation. Unique ID. |
+| **New** | Pink Chip Edge | Recently discovered (less than 14 days old). |
+| **Excluded** (shown on the map as **Ambiguous ID**) | **Red Chip Edge** | **Duplicate ID Detected.** Data from this repeater is currently untrusted. |
 
 ## Multi-Byte Hop Support
 

docs/layers.md

@@ -72,10 +72,11 @@ These layers display the actual mesh network data. You can toggle them on or off
 | **DISC / TRACE** | **Cyan** grid squares showing Node Discovery and Trace packets. |
 | **DEAD** | **Grey** grid squares where a repeater heard the ping, but it didn't route further (sender heard a repeat but no observer did). |
 | **DROP** | **Red** grid squares showing failed pings (neither the sender nor any observers heard repeats of the packet). |
-| **Repeaters** | The icons representing repeater nodes. |
+| **Repeaters** | The chips representing repeater nodes. Each one carries its hex ID, with its state on the chip's left edge and border. See [Repeaters](visuals.md#repeaters). |
 | **Repeater Coverage** | When a repeater is clicked, this layer draws dashed blue lines to all locations where that repeater was heard. Useful for visualizing the effective footprint of a specific repeater. |
 | **Adv. Repeater Coverage** | Similar to standard Repeater Coverage, but colour-codes the lines and grid squares based on the connection type (Green=BIDIR, Orange=TX, etc.) instead of using a uniform blue. Lines are labelled as **In** or **Out** to indicate whether the ping originated inside or outside the region boundary. |
-| **Repeater Neighbours** | Draws lines between repeaters that have heard each other directly, with full support for multi-byte repeater identification. When enabled, coverage pings fade into the background to make the neighbour lines easier to trace. Lines older than 7 days are automatically hidden. <br> - **Green Dashed**: Heard recently (&le; 3 days). <br> - **Orange Solid**: Heard 4-7 days ago. |
+| **Repeater Neighbours** | Draws lines between repeaters that are known to reach each other, with full support for multi-byte repeater identification. When enabled, coverage pings fade into the background to make the neighbour lines easier to trace. All four kinds are drawn solid, so the colour is what tells them apart. Inferred lines are hidden once the region's retention window closes, which is 7 days unless the region administrator changed it. <br> - **Green**: Inferred, seen in a packet path an observer heard within the last 3 days. <br> - **Orange**: Inferred, older than 3 days. <br> - **Blue**: Reported by the repeater over the air. <br> - **Purple**: Uploaded from the app by an admin. <br> See [Links Between Repeaters](visuals.md#links-between-repeaters). |
+| **Backbone** | The smallest set of repeaters whose links together carry half the region's traffic, with **gold** chips for the sites and coloured lines (trunks) between them. Each chip's label shows that repeater's own share. Switching this on hides every repeater that is not a backbone site, turns **Repeaters** on, and turns **Repeater Neighbours** off. See [The Backbone](visuals.md#the-backbone). |
 | **Effective Coverage** | Filters the map to show only locations with confirmed reliable connectivity, removing noise and edge-case pings for a cleaner view of where the mesh truly delivers. Each ping type is given a numerical value (BIDIR being the highest and DROP being the lowest) and these values are averaged across each grid square.|
 | **Signal Strength** | Colour-codes coverage grid squares by signal strength (SNR), making it easy to identify strong and weak zones across the map at a glance. ≤ -1 dB displays in red and ≥ 5 dB in green, with everything else in between. |
 | **Ping Age** | Colour-codes grid squares based on how recently they were last pinged. Green indicates recent activity and red indicates stale coverage. The green and red age thresholds are adjustable from the Settings panel, making it easy to identify areas that may need remapping. |

docs/visuals.md

@@ -1,6 +1,9 @@
-# Map Grid, Ping Types & Popups
+# Understanding Visuals
 
-MeshMapper visualizes mesh coverage using a grid system, colour-coded markers, and detailed popups. This guide explains how to interpret the map data.
+MeshMapper visualizes mesh coverage using a grid system, repeater chips, connecting lines, and detailed popups. This guide explains every mark on the map, in the same order as the **Legend** card in the bottom right corner.
+
+!!! note "Colours on this page are the Default palette"
+    Every colour named below is the Default one. MeshMapper also ships four colour vision palettes (Protanopia, Deuteranopia, Tritanopia and Achromatopsia) under **Settings > Accessibility > Colour Vision**, and each of them remaps these colours. Backbone gold, for example, becomes white in all four. See the [colour vision accessibility options](layers.md#accessibility) for the full list. Where a mark also has a distinctive shape or position, this page says so, so you can find it whichever palette you use.
 
 ## The Grid System
 
@@ -29,6 +32,7 @@ Here is a detailed breakdown of the different coverage statuses:
 
   - **DISCOVERY (DISC)** - *Cyan*
     - Your radio sent a specialized "Discovery" packet, and a node responded.
+    - **TRACE** packets are shown as DISC as well.
 
   - **TRANSMIT (TX)** - *Orange*
     - Your message was successfully sent into the mesh (it reached a repeater), but your radio did not hear the confirmation repeat.
@@ -46,8 +50,124 @@ Here is a detailed breakdown of the different coverage statuses:
     - You sent a message, but no repeaters heard it, and no route was established.
     - Indicates a dead zone or lack of coverage.
 
+One more square colour is not a ping type at all:
+
+  - **Selected** - *Bright Blue* (`#007bff`)
+    - The grid square or ping you have clicked. It replaces that square's normal colour for as long as it is selected.
+
 ![Diagram](https://meshmapper.net/img/pingtypes.png)
 
+## Repeaters
+
+### Chip Anatomy
+
+A repeater is drawn as a small dark rounded chip carrying its hex ID:
+
+  - The **body** is always the same neutral dark slate (`#22303A`), on every state and in every colour vision palette.
+  - The **state** is carried on a thick bar down the **left edge** of the chip, and on the chip's border.
+  - The **ID label** is white on every state.
+
+So the thing to scan for is the **edge colour**, not a coloured blob. There is no solid coloured dot on the map any more.
+
+### Repeater States
+
+| State | Edge Colour | Meaning |
+| --- | --- | --- |
+| **Active** | **Green** (`#2BB673`) | Heard from recently. This is the ordinary state. |
+| **New** | **Pink** (`#FF4D9D`) | First seen by MeshMapper in the last 14 days. Drawn slightly larger, with a glow. |
+| **Aged** | **Grey** (`#8A97A3`) | Has not sent an advert within the window its region administrator set (24 hours unless they changed it). |
+| **Ambiguous ID** | **Red** (`#E0565B`) | Its ID overlaps another repeater at the width it advertises, so pings cannot be attributed to it with certainty. See [Duplicate Repeater IDs](duplicaterepeaterid.md). |
+| **Backbone site** | **Gold** (`#E8B923`) | One of the repeaters carrying the most traffic. See [The Backbone](#the-backbone). |
+
+### Observers
+
+An **observer** is a repeater that also feeds packets to MeshMapper. Its chip carries an eye glyph (👁) in front of the ID.
+
+The eye is a marker, not a state. It rides on top of whatever colour the chip already has, so an observer can be Active, New, Aged or Ambiguous at the same time.
+
+### Groups
+
+When repeaters are too close together to draw apart, they collapse into a round dark **badge**:
+
+  - The **number** is how many repeaters are in the group. Past 1000 it is abbreviated, for example `1.4k`.
+  - The **ring** around the badge is the colour of the state the most of them are in. It is whichever state is commonest, which is not necessarily more than half of them.
+  - The **row of dots** underneath is one dot per state **present** in the group, so a badge with three dots holds repeaters in three different states. The dots are all the same size and say nothing about how many.
+
+**A badge is clickable, which is not obvious.** Clicking it **fans the members out** on spider legs so you can reach a repeater buried in a stack. If the group is both large (more than 18 repeaters) and you are zoomed well out (below zoom 14), it **zooms in** instead. Either way a group can always be opened.
+
+## Links Between Repeaters
+
+The **Repeater Neighbours** overlay in the Layers control draws lines between repeaters that are known to reach each other. There are four kinds, and one more line that only appears when a popup is open. All of them are drawn solid, so the colour is what tells them apart.
+
+| Line Colour | Kind | Meaning |
+| --- | --- | --- |
+| **Green** (`#28a745`) | Inferred, fresh | Seen next to each other in a packet path an observer heard, within the last 3 days. |
+| **Orange** (`#fd7e14`) | Inferred, older | The same, but older than 3 days. The line disappears once the region's retention window closes, which is 7 days unless the region administrator changed it. |
+| **Blue** (`#1e88e5`) | Reported | The repeater reported them as a direct neighbour over the air. |
+| **Purple** (`#8e24aa`) | Uploaded | An admin pulled the repeater's neighbour table and uploaded it from the app. |
+| **Dark Blue** (`#00008b`) | Route path | The one-way route a packet actually took. This one is drawn when you open a ping popup, not by the overlay. |
+
+A **Reported** or **Uploaded** line takes over from an inferred one: if a pair of repeaters has a reported or uploaded link, the green or orange line for that same pair is not drawn.
+
+!!! note "Orange means two different things"
+    An orange **square** is a TX ping. An orange **line** is an older inferred neighbour link. They are unrelated.
+
+## The Backbone
+
+**Backbone** is an overlay you switch on in the Layers control. It answers one question: which handful of repeaters is this region actually leaning on?
+
+The backbone is the **smallest set of repeaters whose links together carry half the region's traffic**. It is measured from inferred links, the ones observers heard, because those are the only links that carry a count. In most regions it comes out at a dozen or two sites.
+
+### Reading the Percentages
+
+Each backbone chip's label carries **its own share** of the region's traffic, for example `A1B2 7.4%`.
+
+**Those shares add up.** Nine chips reading 12%, 9% and 7% are not slices of one bigger number, they sum to roughly the half that defines the backbone. This is the easiest thing on the map to misread.
+
+The gold stamp and the percentage are shown whether or not the Backbone overlay is switched on.
+
+### Gold Does Not Mean Healthy
+
+Gold replaces **Active** and nothing else. A backbone repeater that is New, Aged or Ambiguous keeps its own colour and is still in the backbone set.
+
+This is deliberate: importance must never hide health. It also means **"the gold repeaters are the backbone" is wrong**. Some backbone sites are pink, grey or red.
+
+### Trunks
+
+**Trunks** are the lines drawn between backbone sites. Each site keeps its three busiest links.
+
+A trunk's colour is its **rank band** among all the trunks on the map, busiest to quietest, on a five step ramp:
+
+| Band | Colour |
+| --- | --- |
+| Busiest | `#ff3b30` |
+| | `#ff8c1a` |
+| | `#f5b301` |
+| | `#f5d06f` |
+| Quietest | `#ffe9a8` |
+
+It is a **rank, not a value**, so the colours say which trunks are busier than which, not how much traffic any of them carries. **The line width means nothing**, and the colours do not change as you pan or zoom.
+
+### What the Overlay Does
+
+Switching Backbone on hides every repeater that is not a backbone site, turns the Repeaters layer on if it was off, and switches Repeater Neighbours off. The two overlays cannot be on at once.
+
+### On a Group Map
+
+**A group is scored as one pool.** On a multi-region group map the whole group is treated like a single region, so a chip's share is its share of the group's combined traffic. A small member region ending up with two backbone sites, or none at all, is the correct answer rather than a bug.
+
+## Signal (SNR)
+
+Where the map colours something by signal quality, it uses three bands:
+
+| Band | Colour | Quality |
+| --- | --- | --- |
+| **Over 5 dB** | **Green** (`#1e7e34`) | Strong |
+| **-1 to 5 dB** | **Dark Yellow** (`#856404`) | Moderate |
+| **Under -1 dB** | **Red** (`#bd2130`) | Weak |
+
+If the signal value cannot be read, the mark is drawn in a neutral **Grey** (`#6c757d`) instead.
+
 ## Popups & Data
 
 Clicking on a grid square opens a popup with detailed information.
@@ -74,31 +194,22 @@ You can cycle through individual pings using the **<** and **>** buttons at the
 ### 3. Visual Lines
 When a popup is open, MeshMapper draws lines on the map to visualize the connection:
 
-  - **Solid Coloured Line**: Represents the signal your radio **Heard** from a repeater. The colour indicates signal strength (Green = Good, Orange = Okay, Red = Weak).
-  - **Blue Dashed Line**: Represents the one-way **Via** path.
-  - **Red Dashed Line**: Indicates a connection to a **Duplicate/Excluded** repeater.
+  - **Solid Coloured Line**: Represents the signal your radio **Heard** from a repeater. The colour indicates signal strength (Green = Good, Dark Yellow = Okay, Red = Weak), using the [Signal (SNR)](#signal-snr) bands above.
+  - **Dark Blue Line**: Represents the one-way **Via** path, also called the route path.
+  - **Red Line**: Indicates a connection to a **Duplicate/Excluded** repeater. Its label reads `Duplicate` above the distance.
 
 ### 4. Sharing
 
 Every popup includes a **Link Icon** (chain link) in the top-right corner. Clicking this copies a direct URL to that specific grid square or ping to your clipboard, allowing you to share exact locations with others.
 
-## Repeater Icons
-
-The icons representing repeaters on the map change colour based on their status:
-
-  - **Pink**: **Active**. The repeater is active and online.
-  - **Orange**: **New**. The repeater was discovered by MeshMapper within the last 14 days.
-  - **Grey**: **Stale / Inactive**. The repeater has not sent an advert within the predetermined timeframe (set by the regional administrators).
-  - **Red**: **Ambiguous / Disabled**. The repeater's ID collides with another repeater (a duplicate), or it has been manually disabled.
-
 ## Repeater Popups
 
-Clicking on a repeater icon opens a popup with details:
+Clicking on a repeater chip opens a popup with details:
 
   - **Status Indicators**:
     - **Repeater Online**: The repeater has been heard from recently.
-    - **New Repeater (Orange)**: First seen within the last 14 days.
-    - **Stale Repeater (Grey)**: Has not been heard from in a specific timeframe set by the region administrator (e.g., 24 hours).
+    - **New Repeater (Pink)**: First seen within the last 14 days.
+    - **Aged Repeater (Grey)**: Has not been heard from in a specific timeframe set by the region administrator (e.g., 24 hours).
     - **Ambiguous (Red)**: The repeater's ID collides with another repeater at its byte width.
     - A red warning row appears if the repeater's clock is off by more than 120 seconds ("Repeater time is not set correctly").
   - **Details**:
@@ -107,7 +218,7 @@ Clicking on a repeater icon opens a popup with details:
     - **Last Heard**: The exact time the repeater was last seen by the mesh.
     - **Max Range**: The furthest distance a user has successfully connected to this repeater from.
   - **Stats & Chart**: Per-type ping counts (BIDIR / TX / RX / DISC / DEAD) and a signal-vs-distance chart built from the repeater's coverage data.
-  - **Neighbours**: A list of other repeaters this node has directly communicated with recently.
+  - **Neighbours**: A list of other repeaters this node has been linked to, with the source of each link marked **I** (inferred), **R** (reported) or **U** (uploaded). See [Links Between Repeaters](#links-between-repeaters).
   - **Add Another**: Compare mode — select additional repeaters to view their coverage side by side.
   - **Copy Link**: A link icon in the top right allows you to copy a direct URL to this repeater.
 
@@ -119,4 +230,4 @@ If a repeater's name ends with the "no entry" emoji (🚫), it is treated as a *
 
   - **Map**: The repeater's Name, Location, and ID are completely removed from the map.
   - **Pings**: Coverage data is still kept and displayed on the grid, but the repeater's identity in the popup is masked as `(hidden)`.
-  - **Leaderboards**: The repeater's name is replaced with "(private repeater)", though its statistics are still calculated and ranked.
+  - **Leaderboards**: The repeater's name is replaced with "(private repeater)", though its statistics are still calculated and ranked.