diff --git a/ingestion/internal/wiki/slug.go b/ingestion/internal/wiki/slug.go
new file mode 100644
index 0000000..ab39b46
--- /dev/null
+++ b/ingestion/internal/wiki/slug.go
@@ -0,0 +1,28 @@
+// ingestion/internal/wiki/slug.go
+package wiki
+
+import (
+	"strings"
+	"unicode"
+)
+
+// Slug converts a title to a kebab-case slug suitable for wiki filenames.
+// Rules: lowercase, spaces/hyphens/underscores → hyphens, strip everything else.
+func Slug(title string) string {
+	var b strings.Builder
+	prevHyphen := true // start true to trim leading hyphens
+	for _, r := range strings.ToLower(title) {
+		switch {
+		case r == ' ' || r == '-' || r == '_':
+			if !prevHyphen {
+				b.WriteRune('-')
+				prevHyphen = true
+			}
+		case unicode.IsLetter(r) || unicode.IsDigit(r):
+			b.WriteRune(r)
+			prevHyphen = false
+		// all other characters (apostrophes, colons, dots, etc.) are dropped
+		}
+	}
+	return strings.TrimRight(b.String(), "-")
+}
diff --git a/ingestion/internal/wiki/slug_test.go b/ingestion/internal/wiki/slug_test.go
new file mode 100644
index 0000000..cbed678
--- /dev/null
+++ b/ingestion/internal/wiki/slug_test.go
@@ -0,0 +1,29 @@
+// ingestion/internal/wiki/slug_test.go
+package wiki
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSlug(t *testing.T) {
+	tests := []struct {
+		input string
+		want  string
+	}{
+		{"Domain Driven Design", "domain-driven-design"},
+		{"It's Complicated", "its-complicated"},
+		{"gRPC", "grpc"},
+		{"GPT-4o", "gpt-4o"},
+		{"Property 1: It's Rough", "property-1-its-rough"},
+		{"  leading spaces  ", "leading-spaces"},
+		{"multiple   spaces", "multiple-spaces"},
+		{"already-kebab", "already-kebab"},
+	}
+	for _, tc := range tests {
+		t.Run(tc.input, func(t *testing.T) {
+			assert.Equal(t, tc.want, Slug(tc.input))
+		})
+	}
+}
diff --git a/ingestion/internal/wiki/types.go b/ingestion/internal/wiki/types.go
new file mode 100644
index 0000000..b555d91
--- /dev/null
+++ b/ingestion/internal/wiki/types.go
@@ -0,0 +1,24 @@
+// ingestion/internal/wiki/types.go
+package wiki
+
+// PageType identifies the wiki subdirectory for a page.
+type PageType string
+
+const (
+	PageTypeConcept PageType = "concepts"
+	PageTypeEntity  PageType = "entities"
+	PageTypeSource  PageType = "sources"
+)
+
+// Page is a wiki page to be written to disk.
+type Page struct {
+	Path    string // relative to brainDir, e.g. "wiki/sources/foo.md"
+	Content string // full markdown including YAML frontmatter
+}
+
+// Entry is a summary of an existing wiki page used to build the inventory.
+type Entry struct {
+	Slug  string
+	Title string
+	Type  PageType
+}