Add cross-platform global git hooks to strip AI-generated commit trailers

.github/workflows/test-git-hooks.yml

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+name: Test git hooks
+
+on:
+  push:
+    paths:
+      - 'git-hooks/**'
+      - '.github/workflows/test-git-hooks.yml'
+  pull_request:
+    paths:
+      - 'git-hooks/**'
+      - '.github/workflows/test-git-hooks.yml'
+
+jobs:
+  test:
+    name: Pester tests (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    permissions:
+      contents: read
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Pester
+        shell: pwsh
+        run: |
+          if (-not (Get-Module -ListAvailable -Name Pester | Where-Object { $_.Version -ge '5.0' })) {
+            Install-Module -Name Pester -MinimumVersion 5.0 -Force -SkipPublisherCheck -Scope CurrentUser
+          }
+          Import-Module Pester -MinimumVersion 5.0
+
+      - name: Make bash hook executable
+        if: runner.os != 'Windows'
+        run: chmod +x git-hooks/commit-msg
+
+      - name: Run Pester tests
+        shell: pwsh
+        run: |
+          $config = New-PesterConfiguration
+          $config.Run.Path = 'git-hooks/tests/commit-msg.Tests.ps1'
+          $config.Output.Verbosity = 'Detailed'
+          $config.TestResult.Enabled = $true
+          $config.TestResult.OutputPath = 'test-results.xml'
+          $config.Run.Exit = $true
+          Invoke-Pester -Configuration $config
+
+      - name: Upload test results
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: test-results-${{ matrix.os }}
+          path: test-results.xml

git-hooks/commit-msg

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+#!/usr/bin/env bash
+# commit-msg git hook
+# Strips AI-generated trailer lines from commit messages while preserving
+# human Co-authored-by, Signed-off-by, and all other content.
+#
+# Handles (case-insensitive) lines such as:
+#   Made-with: Cursor
+#   Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
+#   Co-authored-by: GitHub Copilot <noreply@github.com>
+#   Co-authored-by: Amazon Q <q@amazon.com>
+#   Generated-by: GitHub Copilot
+
+COMMIT_MSG_FILE="$1"
+[ -f "$COMMIT_MSG_FILE" ] || exit 0
+
+# 1. Trailer keys that always indicate AI-generated content
+MARKER_PATTERN='^[[:space:]]*(made-with|generated-by|suggested-by)[[:space:]]*:'
+
+# 2. Co-authored-by lines where the author name starts with a known AI tool
+#    The trailing ([[:space:]]|<|$) ensures we match whole words (e.g. "Claude"
+#    but also "Claude Opus 4.6" while not matching a hypothetical "Claudette").
+AI_NAMES_PATTERN='^[[:space:]]*co-authored?-by[[:space:]]*:[[:space:]]*(github[[:space:]]+copilot|copilot|claude|amazon[[:space:]]+q|amazon[[:space:]]+codewhisperer|codewhisperer|gemini|chatgpt|gpt-?[[:digit:]]|codeium|tabnine|windsurf|opencode)([[:space:]]|<|$)'
+
+# 3. Co-authored-by lines whose email domain belongs to a known AI provider
+AI_EMAIL_PATTERN='^[[:space:]]*co-authored?-by[[:space:]]*:.*<[^>]*@(anthropic\.com|cursor\.sh|codeium\.com|cognition\.ai)[^>]*>'
+
+tmp=$(mktemp) || exit 1
+trap 'rm -f "$tmp"' EXIT
+
+while IFS= read -r line || [ -n "$line" ]; do
+    # Strip trailing carriage return to handle CRLF input safely
+    line="${line%$'\r'}"
+
+    if printf '%s\n' "$line" | grep -qiE "$MARKER_PATTERN"; then
+        continue
+    fi
+    if printf '%s\n' "$line" | grep -qiE "$AI_NAMES_PATTERN"; then
+        continue
+    fi
+    if printf '%s\n' "$line" | grep -qiE "$AI_EMAIL_PATTERN"; then
+        continue
+    fi
+    printf '%s\n' "$line"
+done < "$COMMIT_MSG_FILE" > "$tmp"
+
+# Remove trailing blank lines to avoid leaving a dangling blank when all
+# trailers were stripped, then overwrite the original commit-msg file.
+awk '/[^[:space:]]/{last=NR} {lines[NR]=$0} END{for(i=1;i<=last;i++) print lines[i]}' \
+    "$tmp" > "$COMMIT_MSG_FILE"

git-hooks/commit-msg.ps1

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+#Requires -Version 5.1
+# commit-msg git hook (PowerShell version)
+# Strips AI-generated trailer lines from commit messages while preserving
+# human Co-authored-by, Signed-off-by, and all other content.
+#
+# Handles (case-insensitive) lines such as:
+#   Made-with: Cursor
+#   Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
+#   Co-authored-by: GitHub Copilot <noreply@github.com>
+#   Co-authored-by: Amazon Q <q@amazon.com>
+#   Generated-by: GitHub Copilot
+
+function Remove-AITrailers {
+    <#
+    .SYNOPSIS
+        Filters AI-generated trailer lines from an array of commit-message lines.
+    .PARAMETER Lines
+        The lines of the commit message to process.
+    .OUTPUTS
+        String[] – the filtered lines with trailing blank lines removed.
+    #>
+    [OutputType([string[]])]
+    param(
+        [Parameter(Mandatory)][AllowEmptyCollection()][AllowEmptyString()][string[]]$Lines
+    )
+
+    # 1. Trailer keys that always indicate AI-generated content
+    $markerPattern = '^\s*(made-with|generated-by|suggested-by)\s*:'
+
+    # 2. Co-authored-by where the name starts with a known AI tool
+    #    The trailing (\s|<|$) keeps whole-word matching so "Claude" still
+    #    matches "Claude Opus 4.6" but won't silently drop "Claudette Smith".
+    $aiNamesPattern = '^\s*co-authored?-by\s*:\s*(github\s+copilot|copilot|claude|amazon\s+q|amazon\s+codewhisperer|codewhisperer|gemini|chatgpt|gpt-?\d+|codeium|tabnine|windsurf|opencode)(\s|<|$)'
+
+    # 3. Co-authored-by whose email domain belongs to a known AI provider
+    $aiEmailPattern = '^\s*co-authored?-by\s*:.*<[^>]*@(anthropic\.com|cursor\.sh|codeium\.com|cognition\.ai)[^>]*>'
+
+    $filtered = [System.Collections.Generic.List[string]]::new()
+    foreach ($line in $Lines) {
+        if ($line -imatch $markerPattern)  { continue }
+        if ($line -imatch $aiNamesPattern) { continue }
+        if ($line -imatch $aiEmailPattern) { continue }
+        $filtered.Add($line)
+    }
+
+    # Remove trailing blank lines
+    while ($filtered.Count -gt 0 -and [string]::IsNullOrWhiteSpace($filtered[$filtered.Count - 1])) {
+        $filtered.RemoveAt($filtered.Count - 1)
+    }
+
+    return $filtered.ToArray()
+}
+
+# Run as a git hook when executed directly (not dot-sourced by tests)
+if ($MyInvocation.InvocationName -ne '.') {
+    $commitMsgFile = if ($args.Count -gt 0) { $args[0] } else { $null }
+    if ($commitMsgFile -and (Test-Path $commitMsgFile)) {
+        $lines = Get-Content -Path $commitMsgFile -Encoding UTF8
+        if ($null -eq $lines) { $lines = @() }
+        $filtered = Remove-AITrailers -Lines $lines
+        # Write back with LF line endings and a final newline
+        $content = if ($filtered.Count -gt 0) { ($filtered -join "`n") + "`n" } else { '' }
+        [System.IO.File]::WriteAllText(
+            $commitMsgFile,
+            $content,
+            [System.Text.Encoding]::UTF8
+        )
+    }
+}

git-hooks/install.ps1

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+#Requires -Version 5.1
+# Installs the global git commit-msg hook on Windows.
+# Configures git to use %LOCALAPPDATA%\git\hooks as the global hooks directory.
+#
+# Two installation modes are supported:
+#   1. Bash hook   – copies commit-msg (works via Git for Windows' bundled bash)
+#   2. PowerShell hook – copies commit-msg.ps1 plus a thin bash shim named
+#      commit-msg that calls pwsh so native PowerShell handles the filtering.
+#
+# By default, mode 1 (bash) is used.  Pass -UsePowerShell to use mode 2.
+
+param(
+    [switch]$UsePowerShell
+)
+
+$ScriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
+$HooksDir  = Join-Path $env:LOCALAPPDATA 'git\hooks'
+
+if (-not (Test-Path $HooksDir)) {
+    New-Item -ItemType Directory -Path $HooksDir -Force | Out-Null
+}
+
+if ($UsePowerShell) {
+    # Copy the PowerShell hook script
+    Copy-Item "$ScriptDir\commit-msg.ps1" "$HooksDir\commit-msg.ps1" -Force
+
+    # Write a minimal bash shim that delegates to pwsh
+    $shim = @'
+#!/usr/bin/env bash
+pwsh -NoProfile -NonInteractive -ExecutionPolicy Bypass \
+     -File "$(dirname "$0")/commit-msg.ps1" "$1"
+'@
+    [System.IO.File]::WriteAllText("$HooksDir\commit-msg", $shim, [System.Text.Encoding]::UTF8)
+    Write-Host "Installed PowerShell commit-msg hook → $HooksDir"
+} else {
+    Copy-Item "$ScriptDir\commit-msg" "$HooksDir\commit-msg" -Force
+    Write-Host "Installed bash commit-msg hook → $HooksDir"
+}
+
+git config --global core.hooksPath $HooksDir
+Write-Host "Global git hooks path set to: $HooksDir"

git-hooks/install.sh

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+#!/usr/bin/env bash
+# Installs the global git commit-msg hook on macOS / Linux.
+# Configures git to use ~/.config/git/hooks as the global hooks directory.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+HOOKS_DIR="${XDG_CONFIG_HOME:-$HOME/.config}/git/hooks"
+
+mkdir -p "$HOOKS_DIR"
+cp "$SCRIPT_DIR/commit-msg" "$HOOKS_DIR/commit-msg"
+chmod +x "$HOOKS_DIR/commit-msg"
+
+git config --global core.hooksPath "$HOOKS_DIR"
+
+echo "Installed commit-msg hook → $HOOKS_DIR/commit-msg"
+echo "Global git hooks path set to: $HOOKS_DIR"