style(site): match the logo height to the license badge in the map footer

Connections come from the links list in map.json instead of only from shared or mentioned resources. Curated ones are solid lines with a reason in the details panel; the text-based ones stay as faint dashed evidence. Tests check names, duplicates and that every technical topic is connected.

.github/workflows/pages.yml

@@ -99,7 +99,7 @@ jobs:
           path: _site
 
   release:
-    name: Release ${{ needs.build.outputs.version }}
+    name: Publish release
     if: github.event_name != 'pull_request' && github.ref == 'refs/heads/master' && needs.build.outputs.release == 'true'
     needs: build
     runs-on: ubuntu-24.04

CONTRIBUTING.md

@@ -30,6 +30,7 @@ Contributions from everyone are welcomed. To keep the roadmap practical, accessi
 - Contributions should match the topics and structure of the roadmap.
 - Areas where contributors have experience or genuine interest should be focused on.
 - If a new topic is thought to make the roadmap more complete, it may be suggested. New topics should be proposed thoughtfully, considering their usefulness and relevance for other learners.
+- Connections between topics on the map are listed in `site/map.json` under `links` as `["Topic", "Other topic", "why they are related"]`, using the names shown on the map. Connect topics that a learner should study together or that depend on each other, and keep the reason to one short sentence. Tests fail if a name is misspelled, a pair is listed twice or a topic has no connection.
 
 ## 6. Versioning and Releases
 

site/app.js

@@ -155,8 +155,33 @@ function topicChips(nodes) {
   }, swatch(n), n.title, h('span', { class: 'n' }, n.total))));
 }
 
-function related(node) {
+// Hand-picked connections of a topic (from map.json), each with the reason it is listed.
+function relatedTopics(node) {
+  const seen = new Set();
+  const items = [];
+  for (const box of node.boxes || []) {
+    for (const { box: other, reason } of box.related || []) {
+      if (seen.has(other)) continue;
+      seen.add(other);
+      items.push({ other, reason });
+    }
+  }
+  return items;
+}
+
+function curatedList(items) {
+  return h('ul', { class: 'related' }, items.map(({ other, reason }) => {
+    const target = other.topics[0];
+    return h('li', {}, h('button', { type: 'button', onclick: () => navigate(target, { reveal: true }) },
+      swatch(target),
+      h('span', {}, other.text),
+      h('span', { class: 'why' }, reason)));
+  }));
+}
+
+function related(node, skip = new Set()) {
   const items = [...node.links]
+    .filter((link) => !skip.has(link.source === node ? link.target : link.source))
     .sort((a, b) => b.weight - a.weight)
     .map((link) => {
       const other = link.source === node ? link.target : link.source;
@@ -282,13 +307,13 @@ function overview(root) {
     section(null, h('div', { class: 'stats' },
       h('div', { class: 'stat' }, h('b', {}, stats.topics), h('span', {}, 'topics')),
       h('div', { class: 'stat' }, h('b', {}, stats.resources), h('span', {}, 'resources')),
-      h('div', { class: 'stat' }, h('b', {}, stats.links), h('span', {}, 'connections')))),
+      h('div', { class: 'stat' }, h('b', {}, state.plan ? state.plan.connections.filter((c) => c.reason).length : stats.links), h('span', {}, 'connections')))),
     state.plan ? section('Diagram topics by area', areaSummary()) : null,
     ...groups.map((g) => section(g.title, topicChips(g.topics))),
     section('How to explore', h('ul', { class: 'howto' },
       h('li', {}, 'Map follows the roadmap diagram: topics sit in Software, Hardware or both, and are colored by importance.'),
       h('li', {}, 'Use the Areas chips to highlight a single area or only the Software ∩ Hardware cross-section.'),
-      h('li', {}, 'Hover or select a topic to see lines to the topics it shares resources with (solid) or is mentioned by (dotted).'),
+      h('li', {}, 'Hover or select a topic to see solid lines to its related topics. Fainter dashed lines come from resources that share or mention a topic.'),
       h('li', {}, 'Outline lists every topic of the README; use it to browse topics that are not on the map.'),
       h('li', {}, 'Press ', h('kbd', {}, '/'), ' to search topics and resources.'))),
     section(null, h('p', { class: 'res-note' }, 'Built from the ',
@@ -325,7 +350,7 @@ function renderPanel(node) {
       node.importance ? h('span', { class: `pill imp-pill ${node.importance}` }, IMPORTANCE[node.importance]) : null,
       h('span', { class: 'pill' }, plural(node.total, 'resource')),
       node.children.length ? h('span', { class: 'pill' }, plural(node.children.length, 'subtopic')) : null,
-      node.links.length ? h('span', { class: 'pill' }, `${node.links.length} connected`) : null)));
+      relatedTopics(node).length ? h('span', { class: 'pill' }, `${relatedTopics(node).length} related`) : null)));
 
   if (node === root) {
     panel.append(...overview(root));
@@ -333,7 +358,11 @@ function renderPanel(node) {
   }
   if (node.description.length) panel.append(section('About', description(node.description)));
   if (node.children.length) panel.append(section('Subtopics', topicChips(node.children)));
-  if (node.links.length) panel.append(section('Connected topics', related(node)));
+  const curated = relatedTopics(node);
+  if (curated.length) panel.append(section('Related topics', curatedList(curated)));
+  const listed = new Set(curated.flatMap(({ other }) => other.topics));
+  const evidence = node.links.filter((link) => !listed.has(link.source === node ? link.target : link.source));
+  if (evidence.length) panel.append(section(curated.length ? 'Also linked by resources' : 'Linked by resources', related(node, listed)));
   panel.append(resources(node));
 }
 

site/diagram.js

@@ -118,15 +118,41 @@ export function linkDiagram(map, data) {
     return null;
   };
 
+  // A connection joins two boxes. `reason` is set for the hand-picked ones in map.json; the rest
+  // are evidence only (a shared resource, or one topic's text naming another).
   const pairs = new Map();
+  const pairFor = (a, b) => {
+    const [p, q] = a.id < b.id ? [a, b] : [b, a];
+    const id = `${p.id}|${q.id}`;
+    if (!pairs.has(id)) pairs.set(id, { a: p, b: q, reason: null, weight: 0, shared: 0, links: [] });
+    return pairs.get(id);
+  };
+
+  const topicBoxes = new Map(boxes.filter((b) => !b.header).map((b) => [b.text, b]));
+  const invalidLinks = [];
+  for (const box of boxes) box.related = [];
+  for (const [from, to, reason] of map.links || []) {
+    const a = topicBoxes.get(from);
+    const b = topicBoxes.get(to);
+    if (!a || !b || a === b || typeof reason !== 'string' || !reason.trim()) {
+      invalidLinks.push(`${from} - ${to}`);
+      continue;
+    }
+    const pair = pairFor(a, b);
+    if (pair.reason) {
+      invalidLinks.push(`${from} - ${to} (listed twice)`);
+      continue;
+    }
+    pair.reason = reason.trim();
+    a.related.push({ box: b, reason: pair.reason });
+    b.related.push({ box: a, reason: pair.reason });
+  }
+
   for (const link of data.links) {
     const a = boxFor(link.source);
     const b = boxFor(link.target);
     if (!a || !b || a === b) continue;
-    const [p, q] = a.id < b.id ? [a, b] : [b, a];
-    const id = `${p.id}|${q.id}`;
-    if (!pairs.has(id)) pairs.set(id, { a: p, b: q, weight: 0, shared: 0, links: [] });
-    const pair = pairs.get(id);
+    const pair = pairFor(a, b);
     pair.weight += link.weight;
     pair.shared += link.shared.length;
     pair.links.push(link);
@@ -139,6 +165,7 @@ export function linkDiagram(map, data) {
     boxFor,
     connections: [...pairs.values()],
     unmatched: boxes.filter((b) => !b.header && !b.topics.length).map((b) => b.text),
+    invalidLinks,
     invalid: boxes.filter((b) => !b.header && !IMPORTANCE_LEVELS.includes(b.importance)).map((b) => `${b.text}: ${b.importance}`),
   };
 }

site/map.css

@@ -21,12 +21,9 @@
 .start-strip,
 .map-toolbar {
   display: flex;
-  flex-wrap: nowrap;
+  flex-wrap: wrap;
   align-items: center;
   gap: 6px;
-  overflow-x: auto;
-  scrollbar-width: thin;
-  padding-bottom: 2px;
 }
 
 .start-strip > *,
@@ -328,15 +325,25 @@
   pointer-events: none;
 }
 
-.link.mention,
-.link-all.mention {
+.link.evidence,
+.link-all.evidence {
   stroke-dasharray: 5 5;
+  stroke-opacity: 0.45;
+}
+
+.link-end {
+  fill: var(--accent);
 }
 
 .link-all {
   stroke-opacity: 0.4;
 }
 
+.link-all.curated {
+  stroke-width: 1.2px;
+  stroke-opacity: 0.28;
+}
+
 .layer-linksAll {
   opacity: 0;
   transition: opacity 0.25s;
@@ -350,10 +357,6 @@
   opacity: 0.2;
 }
 
-.link-end {
-  fill: var(--accent);
-}
-
 .credit-main {
   fill: var(--text);
   font-size: 14px;
@@ -411,11 +414,19 @@
     padding: 8px 10px;
   }
 
+  /* One swipeable row per strip; the fade at the right edge shows there is more. */
   .start-strip,
   .map-toolbar {
     flex-wrap: nowrap;
     overflow-x: auto;
     scrollbar-width: none;
+    padding-right: 28px;
+    mask-image: linear-gradient(90deg, #000 calc(100% - 28px), transparent);
+  }
+
+  .start-strip::-webkit-scrollbar,
+  .map-toolbar::-webkit-scrollbar {
+    display: none;
   }
 
   .start-chip,

site/map.json

@@ -258,6 +258,216 @@
       }
     }
   ],
+  "links": [
+    ["C", "Memory Management", "Pointers, the stack and the heap are managed by hand in C"],
+    ["C++", "Memory Management", "Ownership, RAII and smart pointers decide who frees memory"],
+    ["Rust", "Memory Management", "Ownership and borrowing replace manual memory management"],
+    ["Python", "Memory Management", "Garbage collection; MicroPython has to fit in small RAM"],
+    ["C", "C++", "C++ builds on C, and both are mixed in one firmware project"],
+    ["C", "Compilers / GCC", "The toolchain that turns C code into firmware"],
+    ["C", "Linux Kernel", "The kernel and its drivers are written in C"],
+    ["C", "GDB", "Source-level debugging of C programs"],
+    ["C++", "Design Patterns", "Classic object-oriented patterns are taught in C++"],
+    ["C++", "Qt Framework", "Qt is a C++ framework"],
+    ["Python", "Bash Scripting", "Both automate tooling, tests and build tasks"],
+    ["Python", "SIL / HIL Testing", "Test rigs and HIL benches are often scripted in Python"],
+    ["Python", "Edge AI", "Models are usually trained in Python before deployment"],
+    ["Rust", "Embedded Security", "Memory safety removes a whole class of vulnerabilities"],
+    ["Assembly", "Computer Architecture", "Instructions map directly to registers and the memory model"],
+    ["Assembly", "Compilers / GCC", "Reading compiler output and writing startup code"],
+    ["Assembly", "Interrupts", "Vector tables and context saving are done in assembly"],
+
+    ["Algorithms & Data Structures", "Memory Management", "The data structure you pick decides memory use and allocation"],
+    ["Algorithms & Data Structures", "Digital Signal Processing", "Filters and transforms are algorithms with tight time and memory budgets"],
+    ["Algorithms & Data Structures", "Problem-Solving Skills & Critical Thinking", "Choosing and breaking down an approach"],
+    ["Design Patterns", "State Machines", "The State pattern; many embedded designs are state machines"],
+    ["State Machines", "Interrupts", "Events and interrupts drive state transitions"],
+    ["State Machines", "RTOS Basics", "RTOS tasks are usually written as event-driven state machines"],
+    ["State Machines", "Digital Design", "Finite-state machines are also the core of sequential logic in hardware"],
+
+    ["JTAG / SWD", "OpenOCD", "OpenOCD drives JTAG/SWD debug probes"],
+    ["JTAG / SWD", "GDB", "GDB reaches the target through a JTAG/SWD probe"],
+    ["JTAG / SWD", "Bootloader / DFU", "Flashes the first bootloader and recovers bricked boards"],
+    ["OpenOCD", "GDB", "OpenOCD is the GDB server for most microcontrollers"],
+    ["GDB", "Compilers / GCC", "GDB reads the debug information the compiler emits"],
+    ["GDB", "Problem-Solving Skills & Critical Thinking", "Debugging is structured problem solving"],
+
+    ["Agile / SCRUM", "V-Model", "Two common process models; safety projects often combine them"],
+    ["Agile / SCRUM", "CI/CD Pipelines", "Short iterations rely on automated builds and tests"],
+    ["Agile / SCRUM", "Teamwork & Collaborative Abilities", "Scrum is built around close teamwork"],
+    ["Agile / SCRUM", "Organizational & Time Management Skills", "Sprint planning and prioritising work"],
+    ["V-Model", "Standards & Certifications", "Certified projects follow V-model verification"],
+    ["V-Model", "SIL / HIL Testing", "Integration and system testing on SIL and HIL benches"],
+    ["Git", "SVN", "Both are version control systems; Git is the common choice today"],
+    ["Git", "CI/CD Pipelines", "Pipelines start from commits and pull requests"],
+    ["Git", "Teamwork & Collaborative Abilities", "Branches and code review are how teams share code"],
+    ["Communication Skills", "Teamwork & Collaborative Abilities", "Collaboration depends on clear communication"],
+
+    ["Compilers / GCC", "Make / CMake", "Build systems drive the compiler and linker"],
+    ["Make / CMake", "CI/CD Pipelines", "Pipelines run the same build commands"],
+    ["Make / CMake", "Buildroot / Yocto", "Buildroot and Yocto are build systems for whole Linux images"],
+    ["Bash Scripting", "CI/CD Pipelines", "Most pipeline steps are shell commands"],
+    ["Bash Scripting", "Operating System Fundamentals", "The shell and processes are core OS concepts"],
+    ["Docker", "CI/CD Pipelines", "Containers give pipelines a reproducible toolchain"],
+    ["Docker", "Buildroot / Yocto", "Yocto builds are commonly run in containers"],
+
+    ["TDD & Unit Testing", "CI/CD Pipelines", "Tests run automatically on every change"],
+    ["TDD & Unit Testing", "Hardware Simulation / Emulation", "Tests run on a host against simulated hardware"],
+    ["SIL / HIL Testing", "Hardware Simulation / Emulation", "SIL runs the firmware against simulated hardware"],
+    ["SIL / HIL Testing", "CI/CD Pipelines", "HIL rigs can run as pipeline stages"],
+    ["Standards & Certifications", "Embedded Security", "Security standards such as IEC 62443"],
+    ["Standards & Certifications", "AUTOSAR", "Automotive software is developed to ISO 26262"],
+    ["Standards & Certifications", "PCB Design / EMC", "EMC compliance testing is a certification requirement"],
+
+    ["Embedded Security", "Bootloader / DFU", "Secure boot and signed firmware updates"],
+    ["Embedded Security", "IoT", "Connected devices are exposed to attacks and need secure updates"],
+    ["Embedded Security", "TCP/IP", "TLS runs on top of TCP/IP"],
+    ["Embedded GUI", "Qt Framework", "Qt is a common GUI toolkit on embedded Linux"],
+    ["Embedded GUI", "SPI", "Small displays are often driven over SPI"],
+    ["Embedded GUI", "DMA", "DMA moves frame buffers to the display"],
+    ["IoT", "MQTT", "A common messaging protocol for IoT devices"],
+    ["IoT", "CoAP", "A lightweight request/response protocol for constrained devices"],
+    ["IoT", "Wi-Fi", "A typical uplink for mains-powered devices"],
+    ["IoT", "LoRa", "Long-range, low-power links"],
+    ["IoT", "NB-IoT", "Cellular connectivity for low-power devices"],
+    ["IoT", "Power Management", "Battery-powered nodes need low-power design"],
+    ["Edge AI", "Digital Signal Processing", "Features are extracted from sensor signals before inference"],
+    ["Edge AI", "Sensors & Actuators", "Models run on sensor data"],
+    ["Edge AI", "Power Management", "Inference has to fit a small energy budget"],
+    ["Edge AI", "FPGA Development", "FPGAs are used as inference accelerators"],
+    ["AUTOSAR", "CAN", "AUTOSAR communication stacks run over CAN"],
+    ["AUTOSAR", "Ethernet", "Automotive Ethernet is part of the AUTOSAR stack"],
+    ["AUTOSAR", "RTOS Basics", "AUTOSAR OS is an OSEK-based real-time operating system"],
+
+    ["Operating System Fundamentals", "RTOS Basics", "Scheduling, tasks and synchronisation carry over"],
+    ["Operating System Fundamentals", "Linux Kernel", "Processes, memory and drivers as implemented in Linux"],
+    ["Operating System Fundamentals", "Threading / Parallelism", "Threads and scheduling basics"],
+    ["Operating System Fundamentals", "Memory Management", "Virtual memory and allocators"],
+    ["Operating System Fundamentals", "Computer Architecture", "MMU, privilege levels and caches"],
+    ["Linux Kernel", "Device Drivers", "Drivers are kernel modules"],
+    ["Linux Kernel", "U-Boot", "U-Boot loads the kernel and the device tree"],
+    ["Linux Kernel", "Buildroot / Yocto", "The kernel is configured and built as part of the image"],
+    ["Linux Kernel", "Memory Technologies & File Systems", "Flash-friendly file systems and block layers"],
+    ["Device Drivers", "I2C", "Linux drivers talk to devices over buses like I2C"],
+    ["Device Drivers", "SPI", "Linux drivers talk to devices over buses like SPI"],
+    ["Device Drivers", "GPIO", "Pins are exposed to drivers through the GPIO subsystem"],
+    ["Device Drivers", "Interrupts", "Drivers handle device interrupts"],
+    ["Device Drivers", "USB", "The USB stack needs host and device drivers"],
+    ["Device Drivers", "PCIe", "PCIe devices need kernel drivers"],
+    ["U-Boot", "Bootloader / DFU", "The same job on Linux boards: initialise hardware and load the OS"],
+    ["U-Boot", "Buildroot / Yocto", "Both build and ship the bootloader with the image"],
+    ["Threading / Parallelism", "IPC", "Threads and processes exchange data through IPC"],
+    ["Threading / Parallelism", "RTOS Basics", "RTOS tasks, mutexes and priorities"],
+    ["IPC", "RTOS Basics", "Queues and semaphores are the RTOS form of IPC"],
+
+    ["RTOS Basics", "FreeRTOS", "The most common first RTOS"],
+    ["RTOS Basics", "Zephyr", "The same scheduling, synchronisation and timing concepts"],
+    ["RTOS Basics", "QNX", "The same scheduling, synchronisation and timing concepts"],
+    ["RTOS Basics", "µC/OS", "The same scheduling, synchronisation and timing concepts"],
+    ["RTOS Basics", "RT-Thread", "The same scheduling, synchronisation and timing concepts"],
+    ["RTOS Basics", "Interrupts", "ISRs hand work over to tasks"],
+    ["RTOS Basics", "Timers / Counters", "The tick timer and software timers"],
+    ["FreeRTOS", "Memory Management", "FreeRTOS offers several heap allocation schemes"],
+    ["FreeRTOS", "TCP/IP", "FreeRTOS+TCP is its TCP/IP stack"],
+    ["Zephyr", "Bluetooth", "Zephyr ships its own Bluetooth stack"],
+    ["Zephyr", "Thread", "Zephyr integrates OpenThread"],
+    ["QNX", "IPC", "A microkernel built around message passing"],
+    ["QNX", "Standards & Certifications", "Certified for safety-critical use"],
+
+    ["GPIO", "Interrupts", "Pin edges raise interrupts"],
+    ["GPIO", "PWM", "PWM is a timer-driven GPIO function"],
+    ["GPIO", "Principles of Electric Circuits", "Pull-ups, drive strength and current limits"],
+    ["GPIO", "Breadboarding", "The first experiment: an LED and a button on a breadboard"],
+    ["ADC / DAC", "Sensors & Actuators", "Analog sensors are read through an ADC"],
+    ["ADC / DAC", "DMA", "DMA moves samples without using the CPU"],
+    ["ADC / DAC", "Digital Signal Processing", "Sampling theory and filtering"],
+    ["ADC / DAC", "Timers / Counters", "Timers trigger conversions at a fixed rate"],
+    ["Timers / Counters", "PWM", "PWM is generated by timer hardware"],
+    ["Timers / Counters", "Interrupts", "Timer events raise interrupts"],
+    ["Timers / Counters", "Clock Management", "Timer rates derive from the clock tree"],
+    ["Timers / Counters", "Watchdog", "A watchdog is a special timer"],
+    ["PWM", "Sensors & Actuators", "Drives motors, LEDs and servos"],
+    ["PWM", "Control Theory", "A PID loop outputs a PWM duty cycle"],
+    ["PWM", "Oscilloscope", "Duty cycle and frequency are checked on a scope"],
+    ["Watchdog", "RTOS Basics", "Tasks must check in; a stuck task triggers a reset"],
+    ["Interrupts", "Computer Architecture", "Vector table, priorities and the exception model"],
+    ["DMA", "SPI", "High-throughput transfers without CPU load"],
+    ["DMA", "UART", "Streaming serial data without CPU load"],
+    ["Clock Management", "Power Management", "Clock gating and frequency scaling save power"],
+    ["Clock Management", "UART", "Baud rates derive from the clock"],
+    ["Clock Management", "Oscilloscope", "Checking oscillator and clock output"],
+    ["Power Management", "Interrupts", "Wake-up sources are interrupts"],
+    ["Power Management", "Bluetooth", "BLE is designed around duty cycling"],
+    ["Power Management", "Hardware Design Basics", "Power supply and battery design"],
+    ["Bootloader / DFU", "Memory Technologies & File Systems", "Firmware lives in flash and updates need safe writes"],
+    ["Bootloader / DFU", "USB", "The USB DFU class updates firmware"],
+
+    ["Memory Technologies & File Systems", "Memory Management", "RAM, flash and EEPROM sizes set the memory budget"],
+    ["Memory Technologies & File Systems", "SPI", "SPI flash and SD cards"],
+    ["Hardware Simulation / Emulation", "Digital Design", "Logic is verified in simulation before hardware exists"],
+    ["Hardware Simulation / Emulation", "FPGA Development", "HDL designs are simulated before synthesis"],
+    ["Hardware Simulation / Emulation", "Principles of Electric Circuits", "Circuits can be simulated (SPICE) before they are built"],
+    ["Sensors & Actuators", "I2C", "Most digital sensors use I2C"],
+    ["Sensors & Actuators", "SPI", "Faster sensors use SPI"],
+    ["Sensors & Actuators", "Digital Signal Processing", "Raw readings are filtered and calibrated"],
+    ["Sensors & Actuators", "Control Theory", "Closed-loop control reads sensors and drives actuators"],
+    ["Digital Signal Processing", "Control Theory", "Filters and controllers share the same math"],
+    ["Digital Signal Processing", "Basic Math & Calculus", "Transforms and filters are applied calculus"],
+    ["Control Theory", "Basic Math & Calculus", "Differential equations and transfer functions"],
+
+    ["UART", "Logic / Protocol Analyzer", "Inspect serial frames and baud rate"],
+    ["UART", "USB", "USB-to-UART bridges are everywhere"],
+    ["UART", "GSM / LTE", "Modems are controlled with AT commands over UART"],
+    ["I2C", "Logic / Protocol Analyzer", "Decode addresses and ACK/NACK"],
+    ["I2C", "SPI", "Both are on-board buses; learn when to choose which"],
+    ["I2C", "Hardware Design Basics", "Pull-up sizing and bus capacitance"],
+    ["SPI", "Logic / Protocol Analyzer", "Decode the clock, chip select and data lines"],
+    ["Bluetooth", "Wi-Fi", "Both share the 2.4 GHz band, often on one radio chip"],
+    ["Bluetooth", "Matter", "Matter devices are commissioned over Bluetooth LE"],
+    ["Bluetooth", "UWB", "UWB is often paired with Bluetooth for secure ranging"],
+    ["Wi-Fi", "TCP/IP", "Wi-Fi carries IP traffic"],
+    ["Wi-Fi", "Matter", "Matter runs on Wi-Fi and Thread"],
+    ["Thread", "Matter", "Matter runs on Wi-Fi and Thread"],
+    ["Thread", "Zigbee", "Both are mesh networks on IEEE 802.15.4 radios"],
+    ["LoRa", "NB-IoT", "Competing low-power wide-area options"],
+    ["Ethernet", "TCP/IP", "Ethernet is the link layer under TCP/IP"],
+    ["Ethernet", "EtherCAT", "Industrial protocols that run on Ethernet hardware"],
+    ["Ethernet", "Profinet", "Industrial protocols that run on Ethernet hardware"],
+    ["USB", "PCIe", "Both are high-speed serial links with host and device roles"],
+    ["PCIe", "FPGA Development", "FPGAs often connect to hosts over PCIe"],
+    ["Modbus", "UART", "Modbus RTU runs over serial lines such as RS-485"],
+    ["Modbus", "TCP/IP", "Modbus TCP runs over TCP/IP"],
+    ["EtherCAT", "FPGA Development", "EtherCAT slave controllers are often built in FPGAs"],
+    ["GSM / LTE", "LTE-M / 5G", "The same cellular family, newer generations"],
+    ["LTE-M / 5G", "NB-IoT", "Both are LTE-based low-power IoT standards"],
+    ["MQTT", "TCP/IP", "MQTT runs over TCP"],
+    ["MQTT", "CoAP", "Two IoT messaging styles: broker-based and request/response"],
+    ["CoAP", "UDP", "CoAP runs over UDP"],
+    ["TCP/IP", "UDP", "The two main transport protocols"],
+    ["CAN", "LIN", "LIN is the low-cost sub-bus beneath CAN in vehicles"],
+    ["CAN", "FlexRay", "FlexRay adds determinism and bandwidth beyond CAN"],
+    ["CAN", "Logic / Protocol Analyzer", "Decode frames and arbitration"],
+    ["CAN", "Oscilloscope", "Check the differential signal and bus termination"],
+    ["MOST", "CAN", "MOST carries media in a vehicle while CAN carries control"],
+    ["MOST", "Ethernet", "Automotive Ethernet is replacing MOST"],
+
+    ["Basic Math & Calculus", "Principles of Electric Circuits", "Circuit analysis uses algebra and calculus"],
+    ["Principles of Electric Circuits", "Electronics Fundamentals", "Components build on circuit laws"],
+    ["Principles of Electric Circuits", "Multimeter", "Verify voltages and currents in real circuits"],
+    ["Electronics Fundamentals", "Digital Design", "Logic gates are built from transistors"],
+    ["Electronics Fundamentals", "Hardware Design Basics", "Choosing components and sizing circuits"],
+    ["Electronics Fundamentals", "Oscilloscope", "Observe how signals change over time"],
+    ["Digital Design", "Computer Architecture", "CPUs are built from digital logic"],
+    ["Digital Design", "FPGA Development", "HDL describes digital logic"],
+    ["Multimeter", "Breadboarding", "Continuity and voltage checks on prototypes"],
+    ["Multimeter", "Soldering / Rework", "Checking for shorts after soldering"],
+    ["Oscilloscope", "Logic / Protocol Analyzer", "Analog view and decoded digital view of the same signals"],
+    ["Oscilloscope", "PCB Design / EMC", "Measuring noise and ringing"],
+    ["Breadboarding", "Hardware Design Basics", "Prototype first, then design the board"],
+    ["Breadboarding", "Soldering / Rework", "From breadboard to soldered prototype"],
+    ["Hardware Design Basics", "PCB Design / EMC", "Schematics become board layout"],
+    ["PCB Design / EMC", "Soldering / Rework", "Boards must allow assembly and repair"]
+  ],
   "groups": {
     "Operating Systems": ["osBase", "linux", "rtos"],
     "Microcontrollers": ["rtos", "mcu"],

site/mapview.js

@@ -206,11 +206,12 @@ export function createMapView({ root, plan, data, build, onSelect }) {
   };
   creditLine(fy + 35, 'Creator & Maintainer: ', CREDITS.author);
   if (build) creditLine(fy + 53, 'Revision: ', `${build.version}  ·  Last update: ${build.date}`);
-  const logoSize = 52;
   const badge = { w: 103, h: 36 };
-  svg('image', { href: 'assets/logo.svg', x: fr - logoSize, y: fy, width: logoSize, height: logoSize }, credits);
+  const logoSize = badge.h;
+  const iconY = fy + 9;
+  svg('image', { href: 'assets/logo.svg', x: fr - logoSize, y: iconY, width: logoSize, height: logoSize }, credits);
   const badgeX = fr - logoSize - SPACE - badge.w;
-  svg('image', { href: 'assets/cc-by-sa.svg', x: badgeX, y: fy + (logoSize - badge.h) / 2, width: badge.w, height: badge.h }, link(CREDITS.licenseUrl));
+  svg('image', { href: 'assets/cc-by-sa.svg', x: badgeX, y: iconY, width: badge.w, height: badge.h }, link(CREDITS.licenseUrl));
   const licenseText = svg('text', { x: badgeX - 14, y: fy + 22, 'text-anchor': 'end', class: 'credit-text' }, link(CREDITS.licenseUrl));
   licenseText.textContent = 'This work is licensed under the Creative Commons';
   const licenseText2 = svg('text', { x: badgeX - 14, y: fy + 40, 'text-anchor': 'end', class: 'credit-text' }, link(CREDITS.licenseUrl));
@@ -293,8 +294,8 @@ export function createMapView({ root, plan, data, build, onSelect }) {
       h('strong', {}, topic.title),
       topic.areas.length ? h('div', { class: 'tip-areas' }, areaDots(topic.areas), areaLabel(topic.areas)) : null,
       h('div', { class: 'tip-meta' }, [importance ? IMPORTANCE[importance] : null, plural(topic.total, 'resource'),
-        topic.links && topic.links.length ? `${topic.links.length} connected` : null].filter(Boolean).join(' · ')),
-      h('div', { class: 'tip-hint' }, 'Click for details and resources'),
+        box && box.related.length ? `${box.related.length} related` : null].filter(Boolean).join(' · ')),
+      h('div', { class: 'tip-hint' }, 'Click this topic to open its details'),
     ].filter(Boolean));
     tip.hidden = false;
     moveTip(e);
@@ -325,8 +326,8 @@ export function createMapView({ root, plan, data, build, onSelect }) {
   function drawConnection(connection, layer, cls) {
     svg('path', {
       d: curve(connection.a, connection.b),
-      class: `${cls} ${connection.shared ? 'shared' : 'mention'}`,
-      'stroke-width': (1.4 + Math.min(3, Math.sqrt(connection.weight) * 0.7)).toFixed(2),
+      class: `${cls} ${connection.reason ? 'curated' : 'evidence'}`,
+      'stroke-width': connection.reason ? 2.4 : 1.4,
     }, layer);
     if (cls !== 'link') return;
     for (const box of [connection.a, connection.b]) {
@@ -335,7 +336,8 @@ export function createMapView({ root, plan, data, build, onSelect }) {
     }
   }
 
-  for (const connection of connections) drawConnection(connection, layers.linksAll, 'link-all');
+  // The overview of all connections only shows the hand-picked ones.
+  for (const connection of connections) if (connection.reason) drawConnection(connection, layers.linksAll, 'link-all');
 
   const isWithin = (node, topic) => {
     for (let n = node; n; n = n.parent) if (n === topic) return true;
@@ -353,7 +355,7 @@ export function createMapView({ root, plan, data, build, onSelect }) {
       for (const b of own) lit.add(b);
       for (const connection of connections) {
         if (!(own.has(connection.a) || own.has(connection.b))) continue;
-        if (!connection.links.some((l) => isWithin(l.source, topic) || isWithin(l.target, topic))) continue;
+        if (!connection.reason && !connection.links.some((l) => isWithin(l.source, topic) || isWithin(l.target, topic))) continue;
         drawConnection(connection, layers.links, 'link');
         lit.add(connection.a);
         lit.add(connection.b);
@@ -423,10 +425,11 @@ export function createMapView({ root, plan, data, build, onSelect }) {
     fitButton.title = 'Show the whole page';
   }
 
+  const pageFitWidth = (size) => Math.max(page.w, (page.h + 40) / (size ? size.h / size.w : page.h / page.w)) + 40;
+
   function fitPage() {
     const size = canvasSize();
-    const aspect = size ? size.h / size.w : page.h / page.w;
-    const width = Math.max(page.w, (page.h + 40) / aspect) + 40;
+    const width = pageFitWidth(size);
     fitMode = 'page';
     setView({ x: (page.w - width) / 2, y: 0, w: width });
     fitButton.title = 'Fit the width';
@@ -446,7 +449,9 @@ export function createMapView({ root, plan, data, build, onSelect }) {
     const size = canvasSize();
     if (!size) return;
     const scale = (size.w / v.w) * factor;
-    if (scale < (size.w / page.w) * MIN_ZOOM || scale > MAX_ZOOM) return;
+    // Limits only stop a step that goes further out of range; the whole-page view is always reachable.
+    const minScale = Math.min((size.w / page.w) * MIN_ZOOM, size.w / pageFitWidth(size), size.w / v.w);
+    if (factor > 1 ? scale > MAX_ZOOM : scale < minScale) return;
     const [px, py] = clientX == null ? [v.x + v.w / 2, v.y + v.h / 2] : toChart(clientX, clientY);
     fitMode = 'custom';
     setView({ x: px - (px - v.x) / factor, y: py - (py - v.y) / factor, w: v.w / factor });

site/parser.test.mjs

@@ -71,6 +71,17 @@ test('places topics in the map areas and their cross-section', () => {
   assert.equal(find('Projects').areas.length, 0, 'getting-started topics are not on the map');
 });
 
+test('every map topic is connected to related topics, each connection with a reason', () => {
+  const plan = linkDiagram(map, data);
+  assert.deepEqual(plan.invalidLinks, [], 'map.json "links" name existing topics, once, with a reason');
+  // Soft skills describe the engineer, not the technology, so some of them stand alone.
+  const alone = plan.boxes.filter((b) => !b.header && !b.areas.includes('SOFT SKILLS') && !b.related.length);
+  assert.deepEqual(alone.map((b) => b.text), [], 'topics without a connection');
+  const has = (a, b) => plan.connections.some((c) => c.reason && [c.a.text, c.b.text].sort().join('|') === [a, b].sort().join('|'));
+  assert.ok(has('C', 'Memory Management'));
+  assert.ok(has('Rust', 'Memory Management'));
+});
+
 test('lays the map out on one A4 page with a minimum spacing between boxes', () => {
   const layout = buildLayout(linkDiagram(map, data));
   assert.deepEqual(layout.missing, [], 'every cluster in map.json has a place in layout.js');

site/styles.css

@@ -409,7 +409,8 @@ button {
   padding: 10px 12px;
   border: 1px solid var(--border);
   border-radius: 12px;
-  background: var(--surface-solid);
+  background: color-mix(in srgb, var(--surface-solid) 72%, transparent);
+  backdrop-filter: blur(3px);
   box-shadow: var(--shadow);
   font-size: 13px;
   pointer-events: none;
@@ -426,10 +427,11 @@ button {
 }
 
 .tip-hint {
-  margin-top: 4px;
-  color: var(--accent);
+  margin-top: 6px;
+  padding-top: 6px;
+  border-top: 1px solid var(--border);
+  color: var(--muted);
   font-size: 12px;
-  font-weight: 600;
 }
 
 /* Outline view */
@@ -715,11 +717,9 @@ button {
 
 .related .why {
   grid-column: 2;
-  overflow: hidden;
   color: var(--muted);
   font-size: 12px;
-  text-overflow: ellipsis;
-  white-space: nowrap;
+  line-height: 1.4;
 }
 
 .res-head {