jeduden
diff --git a/‎.mdsmith.yml‎
Lines changed: 1 addition & 1 deletion b/‎.mdsmith.yml‎
Lines changed: 1 addition & 1 deletion
diff --git a/‎cmd/mdsmith/discover.go‎
Lines changed: 13 additions & 0 deletions b/‎cmd/mdsmith/discover.go‎
Lines changed: 13 additions & 0 deletions
diff --git a/‎cmd/mdsmith/discover_test.go‎
Lines changed: 70 additions & 0 deletions b/‎cmd/mdsmith/discover_test.go‎
Lines changed: 70 additions & 0 deletions
diff --git a/‎cmd/mdsmith/main.go‎
Lines changed: 14 additions & 10 deletions b/‎cmd/mdsmith/main.go‎
Lines changed: 14 additions & 10 deletions
diff --git a/‎cmd/mdsmith/mergedriver.go‎
Lines changed: 55 additions & 24 deletions b/‎cmd/mdsmith/mergedriver.go‎
Lines changed: 55 additions & 24 deletions
diff --git a/‎cmd/mdsmith/mergedriver_test.go‎
Lines changed: 100 additions & 3 deletions b/‎cmd/mdsmith/mergedriver_test.go‎
Lines changed: 100 additions & 3 deletions
@@ -122,7 +122,7 @@ overrides:
   - files: ["internal/rules/index.md"]
     rules:
       table-readability:
-        max-rows: 40
+        max-rows: 45
   - files: ["README.md"]
     rules:
       line-length:
 
@@ -0,0 +1,13 @@
+package main
+
+import "github.com/jeduden/mdsmith/internal/githooks"
+
+// discoverFilesWithGeneratedContent is a thin shim around
+// githooks.DiscoverFilesForInstall so the install commands keep their
+// previous "fall back to PLAN.md / README.md when no directives are
+// found" behavior. The shared implementation lives in
+// internal/githooks so the CLI and the MDS048 rule cannot drift on
+// directive matching itself; only the install-time fallback diverges.
+func discoverFilesWithGeneratedContent(repoRoot string, maxBytes int64) []string {
+	return githooks.DiscoverFilesForInstall(repoRoot, maxBytes)
+}
@@ -0,0 +1,70 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDiscoverFilesWithGeneratedContent(t *testing.T) {
+	dir := t.TempDir()
+
+	// Create test markdown files.
+	files := map[string]string{
+		"README.md":         "# Test\n\n<?catalog?>\n<?/catalog?>\n",
+		"PLAN.md":           "# Plan\n\n<?include file: foo.md ?>\n",
+		"doc.md":            "# Normal file\n\nNo directives here.\n",
+		"guide.md":          "# Guide\n\n<?toc?>\n<?/toc?>\n",
+		".hidden/secret.md": "# Hidden\n\n<?catalog?>\n",
+	}
+
+	for name, content := range files {
+		path := filepath.Join(dir, name)
+		require.NoError(t, os.MkdirAll(filepath.Dir(path), 0o755))
+		require.NoError(t, os.WriteFile(path, []byte(content), 0o644))
+	}
+
+	// Test discovery.
+	discovered := discoverFilesWithGeneratedContent(dir, 1024*1024)
+
+	// Should find files with directives (but not hidden files).
+	assert.Contains(t, discovered, "README.md")
+	assert.Contains(t, discovered, "PLAN.md")
+	assert.Contains(t, discovered, "guide.md")
+	assert.NotContains(t, discovered, "doc.md")
+	assert.NotContains(t, discovered, ".hidden/secret.md")
+}
+
+func TestDiscoverFilesWithGeneratedContent_EmptyRepo(t *testing.T) {
+	dir := t.TempDir()
+
+	// Empty repo with no markdown files.
+	discovered := discoverFilesWithGeneratedContent(dir, 1024*1024)
+
+	// Should fall back to defaults.
+	assert.Equal(t, []string{"PLAN.md", "README.md"}, discovered)
+}
+
+func TestDiscoverFilesWithGeneratedContent_NoDirectives(t *testing.T) {
+	dir := t.TempDir()
+
+	// Create markdown files without directives.
+	files := map[string]string{
+		"README.md": "# Test\n\nNormal content.\n",
+		"doc.md":    "# Doc\n\nMore content.\n",
+	}
+
+	for name, content := range files {
+		path := filepath.Join(dir, name)
+		require.NoError(t, os.WriteFile(path, []byte(content), 0o644))
+	}
+
+	// Test discovery.
+	discovered := discoverFilesWithGeneratedContent(dir, 1024*1024)
+
+	// Should fall back to defaults when no directives found.
+	assert.Equal(t, []string{"PLAN.md", "README.md"}, discovered)
+}
@@ -36,6 +36,7 @@ import (
 	_ "github.com/jeduden/mdsmith/internal/rules/fencedcodelanguage"
 	_ "github.com/jeduden/mdsmith/internal/rules/fencedcodestyle"
 	_ "github.com/jeduden/mdsmith/internal/rules/firstlineheading"
+	_ "github.com/jeduden/mdsmith/internal/rules/githooksync"
 	_ "github.com/jeduden/mdsmith/internal/rules/headingincrement"
 	_ "github.com/jeduden/mdsmith/internal/rules/headingstyle"
 	_ "github.com/jeduden/mdsmith/internal/rules/include"
@@ -74,16 +75,17 @@ func main() {
 const usageText = `Usage: mdsmith <command> [flags] [files...]
 
 Commands:
-  check          Lint Markdown files (default when given file arguments)
-  fix            Auto-fix lint issues in place
-  query          Select files by CUE expression on front matter
-  help           Show help for rules and topics
-  metrics        Show and rank shared Markdown metrics
-  merge-driver   Git merge driver for regenerable sections
-  archetypes     Discover, show, and locate archetype schemas
-  kinds          Inspect declared kinds and resolve effective config per file
-  init           Generate a default .mdsmith.yml config file
-  version        Print version and exit
+  check             Lint Markdown files (default when given file arguments)
+  fix               Auto-fix lint issues in place
+  query             Select files by CUE expression on front matter
+  help              Show help for rules and topics
+  metrics           Show and rank shared Markdown metrics
+  merge-driver      Git merge driver for regenerable sections
+  pre-merge-commit  Install/manage pre-merge-commit hook
+  archetypes        Discover, show, and locate archetype schemas
+  kinds             Inspect declared kinds and resolve effective config per file
+  init              Generate a default .mdsmith.yml config file
+  version           Print version and exit
 
 Global flags:
   -h, --help      Show this help
@@ -129,6 +131,8 @@ func run() int {
 		return runMetrics(os.Args[2:])
 	case "merge-driver":
 		return runMergeDriver(os.Args[2:])
+	case "pre-merge-commit":
+		return runPreMergeCommit(os.Args[2:])
 	case "archetypes":
 		return runArchetypes(os.Args[2:])
 	case "kinds":
 
@@ -10,6 +10,7 @@ import (
 
 	"github.com/jeduden/mdsmith/internal/archetype/gensection"
 	fixpkg "github.com/jeduden/mdsmith/internal/fix"
+	"github.com/jeduden/mdsmith/internal/githooks"
 	"github.com/jeduden/mdsmith/internal/lint"
 	vlog "github.com/jeduden/mdsmith/internal/log"
 	"github.com/jeduden/mdsmith/internal/rule"
@@ -27,7 +28,10 @@ Subcommands:
   install [files...]
         Register the merge driver in git config and ensure
         .gitattributes assigns it to the listed files.
-        Default files: PLAN.md README.md
+
+        When no files are specified, automatically discovers
+        files with generated content (catalog, include, toc),
+        falling back to PLAN.md and README.md if none are found.
 
 Git config (set by install):
   merge.mdsmith.driver = '/absolute/path/to/mdsmith' merge-driver run %O %A %B %P
@@ -352,9 +356,40 @@ func hasConflictMarkers(content []byte) bool {
 	return false
 }
 
-// defaultMergeDriverFiles are the files assigned to the merge
-// driver when install is run without explicit file arguments.
-var defaultMergeDriverFiles = []string{"PLAN.md", "README.md"}
+// resolveManagedFiles returns the canonical (repo-relative,
+// forward-slash) list of files to manage for an install command.
+// Both branches — explicit args and auto-discovery — go through
+// githooks.NormalizeManagedPaths so the on-disk artefacts and the
+// drift checker agree on what counts as the canonical form. The
+// second return is the process exit code: 0 on success, 2 on a
+// user-facing error (already printed to stderr).
+func resolveManagedFiles(repoRoot string, args []string) ([]string, int) {
+	if len(args) > 0 {
+		normalized, err := githooks.NormalizeManagedPaths(repoRoot, args)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "mdsmith: %v\n", err)
+			return nil, 2
+		}
+		return normalized, 0
+	}
+	cfg, _, err := loadConfig("")
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "mdsmith: loading config: %v\n", err)
+		return nil, 2
+	}
+	maxBytes, err := resolveMaxInputBytes(cfg, "")
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "mdsmith: %v\n", err)
+		return nil, 2
+	}
+	discovered := discoverFilesWithGeneratedContent(repoRoot, maxBytes)
+	normalized, err := githooks.NormalizeManagedPaths(repoRoot, discovered)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "mdsmith: %v\n", err)
+		return nil, 2
+	}
+	return normalized, 0
+}
 
 // runMergeDriverInstall registers the mdsmith merge driver in
 // the local git config and ensures .gitattributes assigns it.
@@ -378,10 +413,9 @@ func runMergeDriverInstall(args []string) int {
 		return 2
 	}
 
-	// Determine file list: use args if given, else defaults.
-	files := defaultMergeDriverFiles
-	if len(args) > 0 {
-		files = args
+	files, rc := resolveManagedFiles(repoRoot, args)
+	if rc != 0 {
+		return rc
 	}
 
 	attrPath := filepath.Join(repoRoot, ".gitattributes")
@@ -402,29 +436,25 @@ func runMergeDriverInstall(args []string) int {
 	fmt.Fprintf(os.Stderr, "  git config: merge.mdsmith.driver\n")
 	fmt.Fprintf(os.Stderr, "  .gitattributes: %s\n", attrPath)
 	fmt.Fprintf(os.Stderr, "  pre-merge-commit hook: %s\n", hookPath)
+	fmt.Fprintf(os.Stderr,
+		"\nTo also enable drift detection, add this to your .mdsmith.yml:\n\n%s\n",
+		githooks.EnableRuleSnippet("git-hook-sync"))
 	return 0
 }
 
 // preMergeCommitHookMarker identifies the hook as managed by
 // mdsmith so re-running install can safely replace it without
-// stomping on a user-authored hook of the same name.
-const preMergeCommitHookMarker = "# mdsmith merge-driver pre-merge-commit hook"
+// stomping on a user-authored hook of the same name. The canonical
+// constant lives in internal/githooks; this alias keeps existing
+// references in this package and its tests stable.
+const preMergeCommitHookMarker = githooks.PreMergeCommitMarker
 
 // resolveHooksDir returns the directory where git hooks should be
-// installed. It respects core.hooksPath if configured so that
-// installations work correctly in repos that redirect hooks to a
-// custom path (e.g. via git config or a repo management tool).
-// Falls back to .git/hooks when git cannot be queried.
+// installed for the repo at repoRoot. The implementation lives in
+// internal/githooks so the CLI and the git-hook-sync rule resolve
+// the same path.
 func resolveHooksDir(repoRoot string) string {
-	cmd := exec.Command("git", "-C", repoRoot, "rev-parse", "--git-path", "hooks")
-	if out, err := cmd.Output(); err == nil {
-		p := strings.TrimSpace(string(out))
-		if !filepath.IsAbs(p) {
-			p = filepath.Join(repoRoot, p)
-		}
-		return filepath.Clean(p)
-	}
-	return filepath.Join(repoRoot, ".git", "hooks")
+	return githooks.ResolveHooksDir(repoRoot)
 }
 
 // ensurePreMergeCommitHook writes the pre-merge-commit hook so
@@ -480,8 +510,9 @@ func ensurePreMergeCommitHook(repoRoot string, files []string) error {
 		preMergeCommitHookMarker + "\n" +
 		"# Re-runs mdsmith fix once git has resolved every per-file\n" +
 		"# merge, so generated sections reflect the final merged\n" +
-		"# state of every source file. Re-install with:\n" +
+		"# state of every source file. Re-install with either:\n" +
 		"#   mdsmith merge-driver install\n" +
+		"#   mdsmith pre-merge-commit install\n" +
 		"set -e\n" +
 		fixCmds.String()
 
 
@@ -299,6 +299,103 @@ func TestRunMergeDriverInstall_HelpFlag_ExitsZero(t *testing.T) {
 	})
 }
 
+func TestRunMergeDriverInstall_NotInRepo(t *testing.T) {
+	dir := t.TempDir()
+	require.NoError(t, os.WriteFile(filepath.Join(dir, ".git"),
+		[]byte("not a real gitdir"), 0o644))
+	origWd, _ := os.Getwd()
+	require.NoError(t, os.Chdir(dir))
+	t.Cleanup(func() { _ = os.Chdir(origWd) })
+
+	got := captureStderr(func() {
+		assert.Equal(t, 2, runMergeDriverInstall(nil))
+	})
+	assert.Contains(t, got, "not in a git repository")
+}
+
+func TestRunMergeDriverInstall_LoadConfigError(t *testing.T) {
+	dir := t.TempDir()
+	initTestRepo(t, dir)
+	require.NoError(t, os.WriteFile(filepath.Join(dir, ".mdsmith.yml"),
+		[]byte("not: [valid: yaml\n"), 0o644))
+
+	orig := executableFunc
+	t.Cleanup(func() { executableFunc = orig })
+	executableFunc = func() (string, error) { return "/usr/local/bin/mdsmith", nil }
+
+	origWd, _ := os.Getwd()
+	require.NoError(t, os.Chdir(dir))
+	t.Cleanup(func() { _ = os.Chdir(origWd) })
+
+	got := captureStderr(func() {
+		assert.Equal(t, 2, runMergeDriverInstall(nil))
+	})
+	assert.Contains(t, got, "loading config")
+}
+
+func TestRunMergeDriverInstall_BadMaxInputSize(t *testing.T) {
+	dir := t.TempDir()
+	initTestRepo(t, dir)
+	require.NoError(t, os.WriteFile(filepath.Join(dir, ".mdsmith.yml"),
+		[]byte("max-input-size: nonsense\n"), 0o644))
+
+	orig := executableFunc
+	t.Cleanup(func() { executableFunc = orig })
+	executableFunc = func() (string, error) { return "/usr/local/bin/mdsmith", nil }
+
+	origWd, _ := os.Getwd()
+	require.NoError(t, os.Chdir(dir))
+	t.Cleanup(func() { _ = os.Chdir(origWd) })
+
+	got := captureStderr(func() {
+		assert.Equal(t, 2, runMergeDriverInstall(nil))
+	})
+	assert.Contains(t, got, "invalid max-input-size")
+}
+
+func TestRunMergeDriverInstall_RejectsWhitespacePath(t *testing.T) {
+	dir := t.TempDir()
+	initTestRepo(t, dir)
+
+	orig := executableFunc
+	t.Cleanup(func() { executableFunc = orig })
+	executableFunc = func() (string, error) { return "/usr/local/bin/mdsmith", nil }
+
+	origWd, _ := os.Getwd()
+	require.NoError(t, os.Chdir(dir))
+	t.Cleanup(func() { _ = os.Chdir(origWd) })
+
+	got := captureStderr(func() {
+		assert.Equal(t, 2, runMergeDriverInstall([]string{"bad name.md"}))
+	})
+	assert.Contains(t, got, "whitespace")
+}
+
+func TestRunMergeDriverInstall_NoArgsUsesDiscovery(t *testing.T) {
+	dir := t.TempDir()
+	initTestRepo(t, dir)
+
+	// Generate a markdown file with a directive so discovery returns
+	// it instead of the PLAN.md/README.md fallback.
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "guide.md"),
+		[]byte("# Guide\n\n<?catalog?>\n<?/catalog?>\n"), 0o644))
+
+	orig := executableFunc
+	t.Cleanup(func() { executableFunc = orig })
+	executableFunc = func() (string, error) { return "/usr/local/bin/mdsmith", nil }
+
+	origWd, _ := os.Getwd()
+	require.NoError(t, os.Chdir(dir))
+	t.Cleanup(func() { _ = os.Chdir(origWd) })
+
+	got := captureStderr(func() {
+		assert.Equal(t, 0, runMergeDriverInstall(nil))
+	})
+	assert.Contains(t, got, "merge driver 'mdsmith' installed")
+	// Make sure the snippet print landed too.
+	assert.Contains(t, got, "git-hook-sync: true")
+}
+
 // --- resolveInstalledBinary ---
 
 func TestResolveInstalledBinary_NonTemporaryExe(t *testing.T) {
@@ -704,7 +801,7 @@ func TestResolveHooksDir_DefaultGitRepo(t *testing.T) {
 	// Derive expected path from git itself so the test is resilient
 	// against a global core.hooksPath set in the developer's git config.
 	dir := t.TempDir()
-	require.NoError(t, exec.Command("git", "init", dir).Run())
+	initTestRepo(t, dir)
 	out, err := exec.Command("git", "-C", dir, "rev-parse", "--git-path", "hooks").Output()
 	require.NoError(t, err)
 	expected := strings.TrimSpace(string(out))
@@ -717,7 +814,7 @@ func TestResolveHooksDir_DefaultGitRepo(t *testing.T) {
 
 func TestResolveHooksDir_CustomRelativeHooksPath(t *testing.T) {
 	dir := t.TempDir()
-	require.NoError(t, exec.Command("git", "init", dir).Run())
+	initTestRepo(t, dir)
 	require.NoError(t, exec.Command("git", "-C", dir, "config",
 		"core.hooksPath", "custom-hooks").Run())
 	got := resolveHooksDir(dir)
@@ -726,7 +823,7 @@ func TestResolveHooksDir_CustomRelativeHooksPath(t *testing.T) {
 
 func TestResolveHooksDir_CustomAbsoluteHooksPath(t *testing.T) {
 	dir := t.TempDir()
-	require.NoError(t, exec.Command("git", "init", dir).Run())
+	initTestRepo(t, dir)
 	absPath := filepath.Join(dir, "abs-hooks")
 	require.NoError(t, exec.Command("git", "-C", dir, "config",
 		"core.hooksPath", absPath).Run())