AGENTS.md, add coding conventions and layout logistics including code snippets and example programs.

tasks/workstation/linux/software/ai/sandbox.yml

@@ -306,6 +306,190 @@
       # Run all tests
       ./gradlew allTests
       ```
+
+      # Coding Conventions
+
+      Preferences related to how code should be written.
+
+      ## All languages
+
+      If a value is going to be used more than once, even a small path or file
+      name, it should exist in a variable.
+
+      Relative shebangs such as `#!/usr/bin/env bash` and `#!/usr/bin/env node`
+      are always preferred over static shebangs such as `#!/bin/bash`, since
+      scripts are run across a multitude of different systems.
+
+      ### Layout
+
+      Programs should be laid out in 5 sections.
+
+      - Variables
+          - Instantiate global variables and defaults used for parameters which
+          do not get passed an explicit value by the user.
+      - Functions
+          - Functions to be used throughout the program, including the Usage.
+      - Parameters / Validation
+          - Parse the parameters, validate the input, and assign any defaults.
+      - Main
+          - The primary logic of the program, completes the task at hand.
+      - Finish / Cleanup
+          - Typically just `exit 0`, but sometimes a summary of what was done.
+
+      All sections may not always apply, such as with Hugo websites. With
+      projects like Android apps this would apply to each individual function,
+      method, and class. If a section does not need anything, it can be blank.
+
+      ```
+      public static void doThing(String thingName) {
+        // Variables //
+        String thingPrefix = "/place/for/thing/"
+
+        // Functions //
+
+        // Parameters //
+        if (thingName.isEmpty) {
+          Exception e = new Exception("No name passed!");
+          throw e;
+        }
+
+        // Main //
+        runStuff(thingPrefix + thingName);
+
+        // Finish //
+      }
+      ```
+
+      The comments do not need to be included, this example is just as valid,
+      what maytters most is that the 5 section are done in order rather than
+      instantiating variable mid-scope.
+
+      ```
+      public static void doThing(String thingName) {
+        String thingPrefix = "/place/for/thing/"
+
+        if (thingName.isEmpty) {
+          Exception e = new Exception("No name passed!");
+          throw e;
+        }
+
+        runStuff(thingPrefix + thingName);
+      }
+      ```
+
+      `if` statements and loops start new scope, so they also need the layout
+      applied to them. Loops may sometimes require a variable assignment before
+      it begins which is completely okay and does not break the layout rule.
+      This example has a Variables, Validation, Main, and Finish section without
+      the use of labels or comments since the code itself is simple and small.
+
+      ```
+      count=0
+      array="cats dogs giraffes rhinos horses"
+      last_animal=""
+      for animal in $array; do
+        if (( count >= 3 )); then
+          echo "That's enough! We finished at the ${last_animal}."
+          break;
+        fi
+
+        echo "We're looking at ${animal}."
+
+        last_animal=$animal
+        (( count++ ))
+      done
+      ```
+
+      Providing the user's input in error messages is really helpful and can aid
+      their troubleshooting if things are not going according to expectations.
+
+      Example using Bash:
+
+      ```
+      #!/usr/bin/env bash
+
+      ### Variables ###
+
+      declare A B
+      typeset -i a b
+
+      ### Functions ###
+
+      function usage() {
+        status="$1"
+        cat << EOF
+      Usage: add.sh -a NUM -b NUM [-h]
+
+        Adds two numbers and prints out the full equation.
+
+      Example:
+
+        $ add.sh -a 5 -b 25
+        5 + 25 = 30
+      EOF
+        exit $status
+      }
+      function add() {
+        num1="$1"
+        num2="$2"
+        sum=""
+
+        if [[ -z $num1 || -z $num2 ]]; then
+          echo "ERROR: Two numnbers must be passed."
+        fi
+
+        sum=$(( num1 + num2 ))
+        echo "${num1} + ${num2} = ${sum}"
+      }
+
+      ### Parameters ###
+
+      while getopts ':a:b:h' opt; do
+        case $opt in
+          a) A="$OPTARG" ;;
+          b) B="$OPTARG" ;;
+          h) usage 0 ;;
+          *) echo "ERROR: Option $OPTARG not recognized." >&2 && usage 1 ;;
+        esac
+      done
+
+      if [[ -z "$A" || -z "$B" ]]; then
+        echo "ERROR: Both numbers need to be passed. A=${A} B=${B}" >&2
+        usage 2
+      fi
+      a="$A" b="$B"
+      if [[ "$a" != "$A" || "$b" != "$B" ]]; then
+        echo "ERROR: Values contain non-numeric data, please try again." >&2
+        echo "A=${A} B=${B}" >&2
+        usage 3
+      fi
+
+      ### Main ###
+
+      add "$a" "$b"
+
+      ### Finish ###
+
+      unset A B usage add
+      exit 0
+      ```
+
+      ## Bash
+
+      `[[ ]]` are preferred over `[ ]`, `test`, etc. `(( ))` are always fine.
+
+      When defining a function please use both the keyword `function` as well as
+      the `()`, such as `function myfunc() {}`.
+
+      When instantiating global variables, please use `typeset` or `declare`
+      rather than just `VAR1=""; VAR2=""`, such as:
+
+      ```
+      declare VAR1="" VAR2="" BOOL="true" BOOL2="false"
+      typeset -i INT1=0 INT2=99
+      ```
+
+      When doing colored output, `tput` is always preferred over literal values.
     backup: false
     owner: "{{ user }}"
     group: "{{ user }}"