feat(ingestion): add wiki index rebuilder and audit log

ingestion/internal/wiki/index.go

@@ -0,0 +1,71 @@
+// ingestion/internal/wiki/index.go
+package wiki
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// RebuildIndex writes brain/wiki/index.md from the current wiki contents.
+func RebuildIndex(brainDir, date string) error {
+	inv, err := LoadInventory(brainDir)
+	if err != nil {
+		return fmt.Errorf("load inventory: %w", err)
+	}
+
+	total := len(inv[PageTypeConcept]) + len(inv[PageTypeEntity]) + len(inv[PageTypeSource])
+	var sb strings.Builder
+	fmt.Fprintf(&sb, "# Wiki Index\n\n")
+	fmt.Fprintf(&sb, "_Updated: %s — %d pages (%d concepts, %d entities, %d sources)_\n\n",
+		date, total,
+		len(inv[PageTypeConcept]),
+		len(inv[PageTypeEntity]),
+		len(inv[PageTypeSource]))
+
+	for _, pt := range []PageType{PageTypeConcept, PageTypeEntity, PageTypeSource} {
+		entries := inv[pt]
+		if len(entries) == 0 {
+			continue
+		}
+		label := strings.ToUpper(string(pt)[:1]) + string(pt)[1:]
+		fmt.Fprintf(&sb, "## %s\n\n", label)
+		for _, e := range entries {
+			summary := pageFirstSentence(brainDir, e)
+			if summary != "" {
+				fmt.Fprintf(&sb, "- [[%s|%s]] — %s\n", e.Slug, e.Title, summary)
+			} else {
+				fmt.Fprintf(&sb, "- [[%s|%s]]\n", e.Slug, e.Title)
+			}
+		}
+		sb.WriteString("\n")
+	}
+
+	dest := filepath.Join(brainDir, "wiki", "index.md")
+	return os.WriteFile(dest, []byte(sb.String()), 0o644)
+}
+
+func pageFirstSentence(brainDir string, e Entry) string {
+	path := filepath.Join(brainDir, "wiki", string(e.Type), e.Slug+".md")
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return ""
+	}
+	parts := strings.SplitN(string(content), "---", 3)
+	body := string(content)
+	if len(parts) == 3 {
+		body = parts[2]
+	}
+	for _, line := range strings.Split(body, "\n") {
+		line = strings.TrimSpace(line)
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		if len(line) > 100 {
+			return line[:100] + "…"
+		}
+		return line
+	}
+	return ""
+}