Use incremental update in the pre-commit hook (#6)

The pre-commit hook ran "ccg build ." — a full re-parse of the entire
repo on every commit. A commit only changes a few files, so use
"ccg update ." which re-parses just the changed files (hash-based) and
preserves existing graph state. Verified with the real binary that
update builds correctly from an empty graph (first commit) and skips
unchanged files on subsequent runs.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: tae2089

internal/cli/hooks.go

@@ -21,7 +21,9 @@ func buildHookBody(strict bool) string {
 	if strict {
 		lint = "ccg lint --strict"
 	}
-	return "\n" + hookGuardBegin + "\nccg build . && ccg docs && " + lint + "\n" + hookGuardEnd + "\n"
+	// Use the incremental update on commit: it re-parses only the changed files (fast) and
+	// preserves graph state, whereas a full build re-parses the whole repo every commit.
+	return "\n" + hookGuardBegin + "\nccg update . && ccg docs && " + lint + "\n" + hookGuardEnd + "\n"
 }
 
 // newHooksCmd creates the top-level hooks command group.
@@ -49,7 +51,7 @@ func newHooksInstallCmd() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "install",
 		Short: "Install ccg pre-commit git hook",
-		Long: `Install a pre-commit hook that runs "ccg build && ccg docs && ccg lint".
+		Long: `Install a pre-commit hook that runs "ccg update && ccg docs && ccg lint".
 
 Use --strict to block commits when lint finds issues.
 If a pre-commit hook already exists, the ccg block is appended (idempotent).`,

internal/cli/hooks_test.go

@@ -25,7 +25,7 @@ func TestHooksInstall_CreatesPreCommitHook(t *testing.T) {
 	}
 
 	hook := string(content)
-	for _, want := range []string{"#!/bin/sh", "ccg build", "ccg docs", "ccg lint"} {
+	for _, want := range []string{"#!/bin/sh", "ccg update", "ccg docs", "ccg lint"} {
 		if !strings.Contains(hook, want) {
 			t.Errorf("expected %q in hook, got:\n%s", want, hook)
 		}
@@ -106,8 +106,8 @@ func TestHooksInstall_ExistingHook_AppendsWithGuard(t *testing.T) {
 	if !strings.Contains(hook, "existing hook") {
 		t.Errorf("expected original hook content to be preserved")
 	}
-	if !strings.Contains(hook, "ccg build") {
-		t.Errorf("expected ccg build to be appended")
+	if !strings.Contains(hook, "ccg update") {
+		t.Errorf("expected ccg update to be appended")
 	}
 }
 
@@ -134,9 +134,9 @@ func TestHooksInstall_Idempotent(t *testing.T) {
 
 	// Should not have duplicate ccg blocks
 	hook := string(content)
-	first := strings.Index(hook, "ccg build")
-	last := strings.LastIndex(hook, "ccg build")
+	first := strings.Index(hook, "ccg update")
+	last := strings.LastIndex(hook, "ccg update")
 	if first != last {
-		t.Errorf("ccg build appears multiple times in hook (not idempotent):\n%s", hook)
+		t.Errorf("ccg update appears multiple times in hook (not idempotent):\n%s", hook)
 	}
 }