diff --git a/ingestion/internal/pipeline/build.go b/ingestion/internal/pipeline/build.go
index ef09d82..c45fdac 100644
--- a/ingestion/internal/pipeline/build.go
+++ b/ingestion/internal/pipeline/build.go
@@ -14,6 +14,13 @@ import (
 // (derived from the filename, not the LLM title). Pages whose title resolves to an
 // empty slug are skipped and returned as warnings instead.
 func BuildPages(rawPages []RawPage, sourceSlug, date string) ([]wiki.Page, []string) {
+	return BuildPagesIn("", rawPages, sourceSlug, date)
+}
+
+// BuildPagesIn is BuildPages for a wing: sources go to wiki/<wing>/sources/,
+// concepts and entities to wiki/<wing>/facts/ with `kind:` recording which.
+// An empty wing is the retired wiki/{sources,concepts,entities}/ layout.
+func BuildPagesIn(wing string, rawPages []RawPage, sourceSlug, date string) ([]wiki.Page, []string) {
 	out := make([]wiki.Page, 0, len(rawPages))
 	var warnings []string
 	for _, rp := range rawPages {
@@ -28,7 +35,7 @@ func BuildPages(rawPages []RawPage, sourceSlug, date string) ([]wiki.Page, []str
 			warnings = append(warnings, fmt.Sprintf("skipped page with empty title (type: %s)", rp.Type))
 			continue
 		}
-		out = append(out, buildPage(rp, sourceSlug, date))
+		out = append(out, buildPage(rp, sourceSlug, date, wing))
 	}
 	return out, warnings
 }
@@ -42,7 +49,7 @@ func computeSlug(rp RawPage, sourceSlug string) string {
 	return wiki.Slug(rp.Title)
 }
 
-func buildPage(rp RawPage, sourceSlug, date string) wiki.Page {
+func buildPage(rp RawPage, sourceSlug, date, wing string) wiki.Page {
 	var slug, dir string
 	switch rp.Type {
 	case "source":
@@ -59,8 +66,21 @@ func buildPage(rp RawPage, sourceSlug, date string) wiki.Page {
 		dir = "wiki/" + rp.Type
 	}
 
+	hall := ""
+	if wing != "" {
+		switch rp.Type {
+		case "source":
+			hall = "sources"
+		default:
+			hall = "facts"
+		}
+		dir = "wiki/" + wing + "/" + hall
+	}
 	path := dir + "/" + slug + ".md"
 	fm := buildFrontmatter(rp, date)
+	if wing != "" {
+		fm = addWingFrontmatter(fm, wing, hall, rp.Type)
+	}
 
 	return wiki.Page{
 		Path:    path,
@@ -122,6 +142,16 @@ func buildFrontmatter(rp RawPage, date string) string {
 	return sb.String()
 }
 
+// addWingFrontmatter inserts wing/hall (and kind for facts pages) right after
+// the opening fence of an already-built frontmatter block.
+func addWingFrontmatter(fm, wing, hall, rpType string) string {
+	extra := "wing: " + wing + "\nhall: " + hall + "\n"
+	if hall == "facts" {
+		extra += "kind: " + rpType + "\n"
+	}
+	return strings.Replace(fm, "---\n", "---\n"+extra, 1)
+}
+
 func yamlScalar(s string) string {
 	// A raw newline or CR would end the scalar for every line-oriented
 	// frontmatter reader and start a new key (PR #147 review: a title of
diff --git a/ingestion/internal/pipeline/pipeline.go b/ingestion/internal/pipeline/pipeline.go
index c368d7f..7c39691 100644
--- a/ingestion/internal/pipeline/pipeline.go
+++ b/ingestion/internal/pipeline/pipeline.go
@@ -7,6 +7,7 @@ import (
 	"encoding/hex"
 	"errors"
 	"fmt"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/brain"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
 	"io/fs"
 	"os"
@@ -26,6 +27,11 @@ type Config struct {
 	Complete  CompleteFunc
 	ChunkSize int    // 0 = no chunking
 	Schema    string // overrides brain/schema.md when set (useful in tests)
+
+	// Wing, when set, writes into wiki/<wing>/{sources,facts}/ and scopes the
+	// inventory (title resolution, back-references) to that wing alone. Empty
+	// keeps the retired wiki/{sources,concepts,entities}/ layout.
+	Wing string
 }
 
 // Result is the outcome of a pipeline run.
@@ -42,7 +48,16 @@ type Result struct {
 // Run ingests content and writes structured wiki pages to brainDir/wiki/.
 // In dry-run mode, pages are returned but not written to disk.
 func Run(ctx context.Context, cfg Config, brainDir, content, source string, dryRun bool) (Result, error) {
-	inventory, err := wiki.LoadInventory(brainDir)
+	if cfg.Wing != "" && brain.Sanitise(cfg.Wing) != cfg.Wing {
+		return Result{}, fmt.Errorf("invalid wing %q: must be a plain lower-case wing name", cfg.Wing)
+	}
+	var inventory map[wiki.PageType][]wiki.Entry
+	var err error
+	if cfg.Wing != "" {
+		inventory, err = wiki.LoadWingInventory(brainDir, cfg.Wing)
+	} else {
+		inventory, err = wiki.LoadInventory(brainDir)
+	}
 	if err != nil {
 		return Result{}, fmt.Errorf("load inventory: %w", err)
 	}
@@ -60,7 +75,7 @@ func Run(ctx context.Context, cfg Config, brainDir, content, source string, dryR
 	// The merge is already idempotent (#103), so this is cost and signal, not
 	// correctness — which is why it is safe for it to be an early return.
 	bodyHash := hashBody(content)
-	if !dryRun && bodyHash != "" && bodyHash == storedSourceHash(brainDir, sourceSlug) {
+	if !dryRun && bodyHash != "" && bodyHash == storedSourceHash(brainDir, cfg.Wing, sourceSlug) {
 		return Result{Skipped: true, Warnings: []string{
 			fmt.Sprintf("source %q unchanged since last ingest (hash %s) — extraction skipped", source, bodyHash[:12]),
 		}}, nil
@@ -71,7 +86,7 @@ func Run(ctx context.Context, cfg Config, brainDir, content, source string, dryR
 	// only exists once the model has produced a title. So page-aware
 	// extraction (#106) is scoped to the source page: it's the one page every
 	// chunk's prompt can be given in advance.
-	existingPage := readSourcePage(brainDir, sourceSlug)
+	existingPage := readSourcePage(brainDir, cfg.Wing, sourceSlug)
 
 	chunks := Chunk(content, cfg.ChunkSize)
 
@@ -93,7 +108,7 @@ func Run(ctx context.Context, cfg Config, brainDir, content, source string, dryR
 	meta.BodyHash = bodyHash
 	applySourceMeta(allRaw, meta)
 
-	return buildAndWrite(ctx, allRaw, sourceSlug, date, brainDir, source, inventory, allWarnings, dryRun)
+	return buildAndWrite(ctx, cfg.Wing, allRaw, sourceSlug, date, brainDir, source, inventory, allWarnings, dryRun)
 }
 
 // RunRaw runs the pipeline on pre-parsed RawPages, skipping the LLM extraction
@@ -112,12 +127,12 @@ func RunRaw(ctx context.Context, brainDir, source string, rawPages []RawPage, dr
 	sourceSlug := wiki.Slug(source)
 	date := time.Now().UTC().Format("2006-01-02")
 
-	return buildAndWrite(ctx, rawPages, sourceSlug, date, brainDir, source, inventory, nil, dryRun)
+	return buildAndWrite(ctx, "", rawPages, sourceSlug, date, brainDir, source, inventory, nil, dryRun)
 }
 
 // buildAndWrite runs BuildPages through write for both Run and RunRaw.
-func buildAndWrite(ctx context.Context, rawPages []RawPage, sourceSlug, date, brainDir, source string, inventory map[wiki.PageType][]wiki.Entry, warnings []string, dryRun bool) (Result, error) {
-	pages, buildWarnings := BuildPages(rawPages, sourceSlug, date)
+func buildAndWrite(ctx context.Context, wing string, rawPages []RawPage, sourceSlug, date, brainDir, source string, inventory map[wiki.PageType][]wiki.Entry, warnings []string, dryRun bool) (Result, error) {
+	pages, buildWarnings := BuildPagesIn(wing, rawPages, sourceSlug, date)
 	warnings = append(warnings, buildWarnings...)
 	resolved := Resolve(pages, inventory)
 	canonicalized, linkWarnings := CanonicalizeLinks(resolved, inventory)
@@ -158,7 +173,11 @@ func buildAndWrite(ctx context.Context, rawPages []RawPage, sourceSlug, date, br
 	}
 
 	if !dryRun {
-		if err := wiki.RebuildIndex(brainDir, date); err != nil {
+		if wing != "" {
+			if err := brain.BuildWingIndex(brainDir, wing); err != nil {
+				warnings = append(warnings, fmt.Sprintf("rebuild wing index: %v", err))
+			}
+		} else if err := wiki.RebuildIndex(brainDir, date); err != nil {
 			warnings = append(warnings, fmt.Sprintf("rebuild index: %v", err))
 		}
 		if err := wiki.AppendLog(brainDir, source, written, warnings, date); err != nil {
@@ -193,8 +212,12 @@ func hashBody(content string) string {
 // wiki/sources/<sourceSlug>.md, or "" when it doesn't exist yet.
 // It reads through the brain root, regular files only (hyperguild#157): the
 // content goes into the LLM prompt.
-func readSourcePage(brainDir, sourceSlug string) string {
-	raw, err := readBrainFile(brainDir, "wiki/sources/"+sourceSlug+".md")
+func readSourcePage(brainDir, wing, sourceSlug string) string {
+	rel := "wiki/sources/" + sourceSlug + ".md"
+	if wing != "" {
+		rel = "wiki/" + wing + "/sources/" + sourceSlug + ".md"
+	}
+	raw, err := readBrainFile(brainDir, rel)
 	if err != nil {
 		return ""
 	}
@@ -218,8 +241,8 @@ func readBrainFile(brainDir, rel string) ([]byte, error) {
 // Absence always means "extract". That is the fail-safe direction: a missed
 // skip costs one extraction, while a wrong skip loses an update silently — and
 // silence is the failure mode this repo keeps paying for.
-func storedSourceHash(brainDir, sourceSlug string) string {
-	for _, line := range strings.Split(readSourcePage(brainDir, sourceSlug), "\n") {
+func storedSourceHash(brainDir, wing, sourceSlug string) string {
+	for _, line := range strings.Split(readSourcePage(brainDir, wing, sourceSlug), "\n") {
 		if key, value, found := strings.Cut(line, ":"); found && strings.TrimSpace(key) == "source_hash" {
 			return strings.TrimSpace(value)
 		}
diff --git a/ingestion/internal/pipeline/refs.go b/ingestion/internal/pipeline/refs.go
index ba6c08a..ed91c4c 100644
--- a/ingestion/internal/pipeline/refs.go
+++ b/ingestion/internal/pipeline/refs.go
@@ -23,7 +23,7 @@ func injectSourceRefs(pages []wiki.Page, inventory map[wiki.PageType][]wiki.Entr
 
 	var sourceContent string
 	for _, p := range pages {
-		if strings.HasPrefix(p.Path, "wiki/sources/") &&
+		if isSourcePath(p.Path) &&
 			strings.TrimSuffix(filepath.Base(p.Path), ".md") == sourceSlug {
 			sourceContent = p.Content
 			break
@@ -35,7 +35,7 @@ func injectSourceRefs(pages []wiki.Page, inventory map[wiki.PageType][]wiki.Entr
 
 	bySlug := make(map[string]int, len(pages))
 	for i, p := range pages {
-		if !strings.HasPrefix(p.Path, "wiki/sources/") {
+		if !isSourcePath(p.Path) {
 			bySlug[strings.TrimSuffix(filepath.Base(p.Path), ".md")] = i
 		}
 	}
@@ -52,12 +52,13 @@ func injectSourceRefs(pages []wiki.Page, inventory map[wiki.PageType][]wiki.Entr
 		if !ok {
 			continue
 		}
-		b, err := readBrainFile(brainDir, "wiki/"+string(pt)+"/"+slug+".md")
+		path := entryPath(slug, pt, inventory)
+		b, err := readBrainFile(brainDir, path)
 		if err != nil {
 			continue
 		}
 		page := wiki.Page{
-			Path:    "wiki/" + string(pt) + "/" + slug + ".md",
+			Path:    path,
 			Content: string(b),
 		}
 		pages = append(pages, addSourceRef(page, sourceRef))
@@ -88,7 +89,7 @@ func extractWikilinks(content string) map[string]bool {
 // findSourcePage returns the slug and title of the first wiki/sources/ page in pages.
 func findSourcePage(pages []wiki.Page) (slug, title string, found bool) {
 	for _, p := range pages {
-		if strings.HasPrefix(p.Path, "wiki/sources/") {
+		if isSourcePath(p.Path) {
 			slug = strings.TrimSuffix(filepath.Base(p.Path), ".md")
 			title = extractTitle(p.Content)
 			if title == "" {
@@ -111,3 +112,27 @@ func findInInventory(slug string, inventory map[wiki.PageType][]wiki.Entry) (wik
 	}
 	return "", false
 }
+
+// isSourcePath reports whether path is a source page in either layout:
+// wiki/sources/<slug>.md or wiki/<wing>/sources/<slug>.md.
+func isSourcePath(path string) bool {
+	parts := strings.Split(filepath.ToSlash(path), "/")
+	switch {
+	case len(parts) == 3 && parts[0] == "wiki" && parts[1] == "sources":
+		return true
+	case len(parts) == 4 && parts[0] == "wiki" && parts[2] == "sources":
+		return true
+	}
+	return false
+}
+
+// entryPath is the brain-relative path of an inventory page: the recorded Path
+// for a wing-layout entry, else the retired wiki/<type>/<slug>.md.
+func entryPath(slug string, pt wiki.PageType, inventory map[wiki.PageType][]wiki.Entry) string {
+	for _, e := range inventory[pt] {
+		if e.Slug == slug && e.Path != "" {
+			return e.Path
+		}
+	}
+	return "wiki/" + string(pt) + "/" + slug + ".md"
+}
diff --git a/ingestion/internal/pipeline/resolve.go b/ingestion/internal/pipeline/resolve.go
index df08249..e098ca1 100644
--- a/ingestion/internal/pipeline/resolve.go
+++ b/ingestion/internal/pipeline/resolve.go
@@ -32,7 +32,7 @@ func Resolve(proposed []wiki.Page, inventory map[wiki.PageType][]wiki.Entry) []w
 
 	out := make([]wiki.Page, 0, len(proposed))
 	for _, page := range proposed {
-		pt := pageTypeFromPath(page.Path)
+		pt := pageTypeOf(page)
 		title := extractTitle(page.Content)
 		k := key{pt: pt, normalized: normalizeTitle(title)}
 		if canonicalSlug, ok := lookup[k]; ok {
@@ -55,6 +55,22 @@ func normalizeTitle(s string) string {
 	return strings.Join(strings.Fields(s), " ")
 }
 
+// pageTypeOf is the page's type: from its directory in the retired layout, or
+// from `kind:` for a wing-layout facts page (concepts and entities share facts/).
+func pageTypeOf(p wiki.Page) wiki.PageType {
+	parts := strings.Split(filepath.ToSlash(p.Path), "/")
+	if len(parts) >= 4 && parts[0] == "wiki" {
+		switch parts[2] {
+		case "sources":
+			return wiki.PageTypeSource
+		case "facts":
+			pt, _ := wiki.KindFromContent(p.Content)
+			return pt
+		}
+	}
+	return pageTypeFromPath(p.Path)
+}
+
 // pageTypeFromPath extracts the wiki.PageType from a path like "wiki/entities/foo.md".
 func pageTypeFromPath(path string) wiki.PageType {
 	parts := strings.Split(filepath.ToSlash(path), "/")
diff --git a/ingestion/internal/pipeline/root_test.go b/ingestion/internal/pipeline/root_test.go
index b9f7b6c..1e985a8 100644
--- a/ingestion/internal/pipeline/root_test.go
+++ b/ingestion/internal/pipeline/root_test.go
@@ -35,17 +35,17 @@ func TestReadSourcePageAndSchemaRefuseSymlinksAndSurviveSwapRaces(t *testing.T)
 	inBrain := brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
 	require.NoError(t, os.WriteFile(filepath.Join(brain, "wiki", "sources", "ok.md"), []byte("zqinside source"), 0o644))
 	require.NoError(t, os.WriteFile(filepath.Join(brain, "schema.md"), []byte("zqinside schema"), 0o644))
-	assert.Equal(t, "zqinside source", readSourcePage(brain, "ok"), "positive control")
+	assert.Equal(t, "zqinside source", readSourcePage(brain, "", "ok"), "positive control")
 	assert.Equal(t, "zqinside schema", loadSchema(brain), "positive control")
 
 	require.NoError(t, os.Symlink(brainfstest.Outside(t), filepath.Join(brain, "wiki", "sources", "out.md")))
 	require.NoError(t, os.Symlink(filepath.Join("..", "..", "raw", "s.md"), filepath.Join(brain, "wiki", "sources", "in.md")))
-	assert.NotContains(t, readSourcePage(brain, "out"), brainfstest.Sentinel)
-	assert.NotContains(t, readSourcePage(brain, "in"), brainfstest.Sentinel)
-	assert.NotContains(t, storedSourceHash(brain, "in"), brainfstest.Sentinel)
+	assert.NotContains(t, readSourcePage(brain, "", "out"), brainfstest.Sentinel)
+	assert.NotContains(t, readSourcePage(brain, "", "in"), brainfstest.Sentinel)
+	assert.NotContains(t, storedSourceHash(brain, "", "in"), brainfstest.Sentinel)
 
 	src := filepath.Join(brain, "wiki", "sources", "r.md")
-	read := func() string { return readSourcePage(brain, "r") }
+	read := func() string { return readSourcePage(brain, "", "r") }
 	brainfstest.AssertNoLeak(t, src, "zqinside", 1500*time.Millisecond, read)
 	brainfstest.AssertNoLeakFrom(t, src, "zqinside", inBrain, 1500*time.Millisecond, read)
 	brainfstest.AssertNoHang(t, src, "zqinside", 1500*time.Millisecond, 6*time.Second, func() { _ = read() })
diff --git a/ingestion/internal/pipeline/wing_layout_test.go b/ingestion/internal/pipeline/wing_layout_test.go
new file mode 100644
index 0000000..0da280b
--- /dev/null
+++ b/ingestion/internal/pipeline/wing_layout_test.go
@@ -0,0 +1,138 @@
+package pipeline
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func wingCfg(wing string, pages ...RawPage) Config {
+	return Config{
+		Wing:   wing,
+		Schema: "# Schema",
+		Complete: func(context.Context, string, string) (string, error) {
+			return mustJSON(pages), nil
+		},
+	}
+}
+
+func sourceAndEntity() []RawPage {
+	return []RawPage{
+		{Title: "Dark Factory Talk", Type: "source", Subtype: "video", Domain: "ai",
+			Content: "## Summary\n\nA talk.\n\n## Entities Mentioned\n\n[[Jev]]\n"},
+		{Title: "Jev", Type: "entity", Subtype: "tool", Domain: "ai",
+			Content: "## Definition\n\nA decision model.\n\n## Sources\n"},
+	}
+}
+
+func exists(dir, rel string) bool {
+	_, err := os.Stat(filepath.Join(dir, rel))
+	return err == nil
+}
+
+func read(t *testing.T, dir, rel string) string {
+	t.Helper()
+	b, err := os.ReadFile(filepath.Join(dir, rel))
+	require.NoError(t, err)
+	return string(b)
+}
+
+func TestRun_WithAWingWritesIntoThatWingsHalls(t *testing.T) {
+	dir := t.TempDir()
+	_, err := Run(context.Background(), wingCfg("radar", sourceAndEntity()...), dir, "body of the talk", "dark-factory-talk", false)
+	require.NoError(t, err)
+
+	src := read(t, dir, "wiki/radar/sources/dark-factory-talk.md")
+	assert.Contains(t, src, "wing: radar")
+	assert.Contains(t, src, "hall: sources")
+
+	ent := read(t, dir, "wiki/radar/facts/jev.md")
+	assert.Contains(t, ent, "wing: radar")
+	assert.Contains(t, ent, "hall: facts")
+	assert.Contains(t, ent, "kind: entity")
+}
+
+func TestRun_WithAWingDoesNotTouchTheRetiredLayout(t *testing.T) {
+	dir := t.TempDir()
+	_, err := Run(context.Background(), wingCfg("radar", sourceAndEntity()...), dir, "body of the talk", "dark-factory-talk", false)
+	require.NoError(t, err)
+	for _, retired := range []string{"wiki/sources", "wiki/concepts", "wiki/entities"} {
+		assert.False(t, exists(dir, retired), "%s is the retired layout and must not be written", retired)
+	}
+}
+
+func TestRun_WithAWingTheSourceLinksBackFromTheEntity(t *testing.T) {
+	dir := t.TempDir()
+	_, err := Run(context.Background(), wingCfg("radar", sourceAndEntity()...), dir, "body of the talk", "dark-factory-talk", false)
+	require.NoError(t, err)
+	assert.Contains(t, read(t, dir, "wiki/radar/facts/jev.md"), "[[dark-factory-talk|Dark Factory Talk]]")
+}
+
+func TestRun_WithAWingASecondSourceReusesTheSameEntityPage(t *testing.T) {
+	dir := t.TempDir()
+	_, err := Run(context.Background(), wingCfg("radar", sourceAndEntity()...), dir, "first body", "talk-one", false)
+	require.NoError(t, err)
+
+	again := []RawPage{
+		{Title: "Second Talk", Type: "source", Subtype: "video", Content: "## Summary\n\nMore.\n\n## Entities Mentioned\n\n[[The Jev]]\n"},
+		{Title: "The Jev", Type: "entity", Subtype: "tool", Content: "## Definition\n\nStill a decision model.\n\n## Sources\n"},
+	}
+	_, err = Run(context.Background(), wingCfg("radar", again...), dir, "second body", "talk-two", false)
+	require.NoError(t, err)
+
+	files, err := filepath.Glob(filepath.Join(dir, "wiki/radar/facts/*.md"))
+	require.NoError(t, err)
+	assert.Len(t, files, 1, "an entity matched by title (leading article ignored) is merged, not duplicated")
+	assert.Contains(t, read(t, dir, "wiki/radar/facts/jev.md"), "talk-two")
+}
+
+func TestRun_WithAWingNeverMergesIntoAnotherWingsPage(t *testing.T) {
+	dir := t.TempDir()
+	other := "---\ntitle: Jev\nwing: client-x\nhall: facts\nkind: entity\n---\n\n## Definition\n\nPrivate to another wing.\n"
+	require.NoError(t, os.MkdirAll(filepath.Join(dir, "wiki/client-x/facts"), 0o755))
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "wiki/client-x/facts/jev.md"), []byte(other), 0o644))
+
+	_, err := Run(context.Background(), wingCfg("radar", sourceAndEntity()...), dir, "body", "dark-factory-talk", false)
+	require.NoError(t, err)
+
+	assert.Equal(t, other, read(t, dir, "wiki/client-x/facts/jev.md"), "another wing's page is never read into or rewritten")
+	assert.True(t, exists(dir, "wiki/radar/facts/jev.md"))
+}
+
+func TestRun_WithAWingRejectsANameThatIsNotAPlainWing(t *testing.T) {
+	for _, bad := range []string{"../escape", "a/b", "Radar", "has space", "."} {
+		t.Run(bad, func(t *testing.T) {
+			dir := t.TempDir()
+			_, err := Run(context.Background(), wingCfg(bad, sourceAndEntity()...), dir, "body", "talk", false)
+			require.Error(t, err)
+			assert.Len(t, listAll(t, dir), 1, "nothing is written for a rejected wing (only the temp dir itself exists)")
+		})
+	}
+}
+
+func listAll(t *testing.T, dir string) []string {
+	t.Helper()
+	var out []string
+	_ = filepath.WalkDir(dir, func(p string, _ os.DirEntry, _ error) error { out = append(out, p); return nil })
+	return out
+}
+
+// The dangerous path is the back-reference: a source that links [[Jev]] without
+// proposing a Jev page makes the pipeline go and edit an existing Jev page. That
+// lookup must be confined to the target wing.
+func TestRun_WithAWingASourceLinkingToAnotherWingsEntityDoesNotEditIt(t *testing.T) {
+	dir := t.TempDir()
+	other := "---\ntitle: Jev\nwing: client-x\nhall: facts\nkind: entity\n---\n\n## Definition\n\nPrivate to another wing.\n\n## Sources\n"
+	require.NoError(t, os.MkdirAll(filepath.Join(dir, "wiki/client-x/facts"), 0o755))
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "wiki/client-x/facts/jev.md"), []byte(other), 0o644))
+
+	onlySource := sourceAndEntity()[:1]
+	_, err := Run(context.Background(), wingCfg("radar", onlySource...), dir, "body", "dark-factory-talk", false)
+	require.NoError(t, err)
+
+	assert.Equal(t, other, read(t, dir, "wiki/client-x/facts/jev.md"), "no back-reference may be written into another wing")
+}
diff --git a/ingestion/internal/wiki/inventory.go b/ingestion/internal/wiki/inventory.go
index 00b67cd..c9e3d4e 100644
--- a/ingestion/internal/wiki/inventory.go
+++ b/ingestion/internal/wiki/inventory.go
@@ -96,3 +96,79 @@ func readFrontmatter(bfs *brainfs.Brain, rel, fallbackSlug string) (title string
 	}
 	return
 }
+
+// LoadWingInventory returns the pages of ONE wing, grouped by type. Sources
+// come from wiki/<wing>/sources/; concepts and entities live together in
+// wiki/<wing>/facts/ and are told apart by their `kind:` frontmatter. A facts
+// page without a kind (a hand-written note) is left out, so extraction can
+// never merge into something it did not create. Other wings are never read.
+func LoadWingInventory(brainDir, wing string) (map[PageType][]Entry, error) {
+	result := map[PageType][]Entry{PageTypeConcept: {}, PageTypeEntity: {}, PageTypeSource: {}}
+	bfs, err := brainfs.Open(brainDir)
+	if err != nil {
+		return nil, fmt.Errorf("open brain: %w", err)
+	}
+	defer func() { _ = bfs.Close() }()
+	for _, hall := range []string{"sources", "facts"} {
+		dir := "wiki/" + wing + "/" + hall
+		names, err := bfs.ReadDirRegular(dir)
+		if errors.Is(err, fs.ErrNotExist) {
+			continue
+		}
+		if err != nil {
+			return nil, fmt.Errorf("read dir %s: %w", dir, err)
+		}
+		for _, name := range names {
+			if !strings.HasSuffix(name, ".md") {
+				continue
+			}
+			rel := dir + "/" + name
+			slug := strings.TrimSuffix(name, ".md")
+			pt := PageTypeSource
+			if hall == "facts" {
+				var ok bool
+				if pt, ok = kindOf(bfs, rel); !ok {
+					continue
+				}
+			}
+			title, aliases := readFrontmatter(bfs, rel, slug)
+			result[pt] = append(result[pt], Entry{Slug: slug, Title: title, Aliases: aliases, Type: pt, Path: rel})
+		}
+	}
+	return result, nil
+}
+
+// kindOf reads `kind:` from a facts page's frontmatter.
+func kindOf(bfs *brainfs.Brain, rel string) (PageType, bool) {
+	content, err := bfs.ReadRegular(rel)
+	if err != nil {
+		return "", false
+	}
+	return KindFromContent(string(content))
+}
+
+// KindFromContent maps frontmatter `kind: concept|entity` to a PageType.
+func KindFromContent(content string) (PageType, bool) {
+	inFM := false
+	for _, line := range strings.Split(content, "\n") {
+		if strings.TrimSpace(line) == "---" {
+			if inFM {
+				break
+			}
+			inFM = true
+			continue
+		}
+		if !inFM {
+			continue
+		}
+		if key, val, ok := strings.Cut(line, ":"); ok && strings.TrimSpace(key) == "kind" {
+			switch strings.Trim(strings.TrimSpace(val), `"'`) {
+			case "concept":
+				return PageTypeConcept, true
+			case "entity":
+				return PageTypeEntity, true
+			}
+		}
+	}
+	return "", false
+}
diff --git a/ingestion/internal/wiki/types.go b/ingestion/internal/wiki/types.go
index 62e74aa..ed8a6c9 100644
--- a/ingestion/internal/wiki/types.go
+++ b/ingestion/internal/wiki/types.go
@@ -22,4 +22,5 @@ type Entry struct {
 	Title   string
 	Aliases []string
 	Type    PageType
+	Path    string // brain-relative path; set for wing-layout entries
 }