feat(instructions): add client overlays

scripts/commands/add-instruction.ps1

@@ -0,0 +1,23 @@
+[CmdletBinding()]
+param(
+    [ValidateSet('Codex','Claude','Both')][string]$Client,
+    [AllowEmptyString()][string]$Instruction,
+    [string]$HomePath = [Environment]::GetFolderPath('UserProfile')
+)
+$ErrorActionPreference = 'Stop'
+$root = Split-Path (Split-Path $PSScriptRoot -Parent) -Parent
+. (Join-Path $root 'scripts/lib/install-targets.ps1')
+
+if (-not $Client) { $Client = Read-InstallClient -Client $Client }
+if (-not $PSBoundParameters.ContainsKey('Instruction')) { $Instruction = Read-Host 'Instruction' }
+if ([string]::IsNullOrWhiteSpace($Instruction) -or $Instruction.Length -gt 65536) { throw 'Instruction must contain between 1 and 65536 characters.' }
+if (-not [System.IO.Path]::IsPathRooted($HomePath)) { throw 'HomePath must be absolute.' }
+
+$directory = Join-Path $HomePath '.my-ai-configuration/instructions'
+New-Item -ItemType Directory -Path $directory -Force | Out-Null
+foreach ($target in $(if ($Client -eq 'Both') { @('codex','claude') } else { @($Client.ToLowerInvariant()) })) {
+    $path = Join-Path $directory "$target.md"
+    $prefix = if ((Test-Path -LiteralPath $path) -and (Get-Item -LiteralPath $path).Length -gt 0 -and -not (Get-Content -LiteralPath $path -Raw).EndsWith([Environment]::NewLine)) { [Environment]::NewLine } else { '' }
+    [System.IO.File]::AppendAllText($path, $prefix + $Instruction.TrimEnd() + [Environment]::NewLine, [System.Text.UTF8Encoding]::new($false))
+    Write-Output "Instruction added for $target."
+}

scripts/commands/add-instruction.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+client=
+instruction=
+home_path=${HOME:?HOME is required}
+while [ $# -gt 0 ]; do
+  case "$1" in
+    --client) client=${2:?--client requires a value}; shift 2 ;;
+    --instruction) instruction=${2:?--instruction requires a value}; shift 2 ;;
+    --home) home_path=${2:?--home requires a value}; shift 2 ;;
+    *) printf 'Unknown argument: %s\n' "$1" >&2; exit 1 ;;
+  esac
+done
+
+case "$client" in
+  codex|Codex) targets=(codex) ;;
+  claude|Claude) targets=(claude) ;;
+  both|Both) targets=(codex claude) ;;
+  '')
+    read -r -p 'Select client (codex, claude, or both) ' client
+    case "$client" in
+      codex|Codex) targets=(codex) ;;
+      claude|Claude) targets=(claude) ;;
+      both|Both) targets=(codex claude) ;;
+      *) printf 'Unknown --client value: %s\n' "$client" >&2; exit 1 ;;
+    esac
+    ;;
+  *) printf 'Unknown --client value: %s\n' "$client" >&2; exit 1 ;;
+esac
+if [ -z "$instruction" ]; then read -r -p 'Instruction ' instruction; fi
+if [ -z "${instruction//[[:space:]]/}" ] || [ ${#instruction} -gt 65536 ]; then printf 'Instruction must contain between 1 and 65536 characters.\n' >&2; exit 1; fi
+case "$home_path" in /*|[A-Za-z]:[\\/]*) ;; *) printf 'Home path must be absolute.\n' >&2; exit 1 ;; esac
+
+directory="$home_path/.my-ai-configuration/instructions"
+mkdir -p -- "$directory"
+for target in "${targets[@]}"; do
+  path="$directory/$target.md"
+  [ ! -s "$path" ] || [ "$(tail -c 1 -- "$path" | wc -l)" -eq 1 ] || printf '\n' >> "$path"
+  printf '%s\n' "$instruction" >> "$path"
+  printf 'Instruction added for %s.\n' "$target"
+done