Keep Unicode letters and numbers in slugs, so a Korean heading names its file in Korean instead of untitled

docs/contributor/architecture.md

@@ -220,10 +220,12 @@ Bun therefore validates everything and derives anything derivable:
   requirement is load-bearing, not tidiness: an in-root write of any other
   file would be arbitrary-file storage in a folder the user syncs.
 - **The view never names a file.** It sends a note's *text*; Bun slugs the
-  heading itself (`slugOf` emits only `[a-z0-9-]`), so filenames are safe by
-  construction and there is no name parameter to validate or smuggle through.
-  Workspace folder names get the same treatment (`createManaged` slugs the
-  display name; renaming a workspace is display-only and touches no folder).
+  heading itself (`slugOf` emits only Unicode letters, their combining marks,
+  numbers and hyphens, in NFC). Filenames are safe by construction: no dots,
+  path separators or control characters, and no name parameter to validate or
+  smuggle through. Workspace folder names get the same treatment
+  (`createManaged` slugs the display name; renaming a workspace is
+  display-only and touches no folder).
 - **Paths are opaque handles.** The view holds only paths and roots it was
   handed by Bun (`workspaceList`, `noteList`, `noteCreate`, `noteDelete`'s
   trashed location) and passes them back unmodified. View code that
@@ -379,10 +381,11 @@ Bun therefore validates everything and derives anything derivable:
   purge, empty, or Trash listing can see them.
 - **A folder is the only name a caller chooses, so it is the only name
   validated.** Filenames never needed a guard: `slugOf` builds them from the
-  note's own heading and emits only `[a-z0-9-]`, so there is no name to check
-  and no way for the view to ask for a path. A folder has to match what is
-  already on disk, so it cannot be slugged into safety, and it arrives from
-  the view, from MCP and from the CLI alike. `folderPathOf` is the one gate:
+  note's own heading and emits only Unicode letters, their combining marks,
+  numbers and hyphens, so there is no name to check and no way for the view
+  to ask for a path. A folder has to match what is already on disk, so it
+  cannot be slugged into safety, and it arrives from the view, from MCP and
+  from the CLI alike. `folderPathOf` is the one gate:
   relative only, no backslashes, no `.` or `..` segment, no dot-entry, inside
   the root once resolved. `..` is rejected on the raw segments rather than
   left to the containment check, so `a/../b` cannot quietly mean `b` — the
@@ -459,7 +462,8 @@ Bun therefore validates everything and derives anything derivable:
   volume) degrades to focus-refresh only, warned, like every other
   unavailable-root path. `rename(2)` overwrites
   silently, so no call site may pick its own destination name: `uniqueName`
-  (case-insensitive, because APFS is) allocates against a `readdir` snapshot
+  (ignoring case and Unicode normalization, because APFS does) allocates
+  against a `readdir` snapshot
   plus the `reserved` set, and the rename that follows is safe *because* the
   allocation already skipped every taken name. A rename whose target didn't
   come from `uniqueName` is a latent data-loss bug.

docs/contributor/remote.md

@@ -568,7 +568,7 @@ installed on sshd's own PATH, such as `/usr/local/bin` on Linux.
 **`.server` is inside the app home**, beside `.client` (§5), because both are
 this machine's role-specific state and one `~/.ledge` is the whole of Ledge on
 a disk. It is dotted because managed workspace folders are created directly in
-the app home under `[a-z0-9-]` slugs, so `server/` or `bin/` could be a
+the app home under slugs of their names, so `server/` or `bin/` could be a
 workspace. `backup.ts` excludes it, and the root watcher and note listing skip
 dotted entries already. The path is spelled literally in `SERVE_COMMAND` and
 in the forced command on every paired server, so `LEDGE_NOTES_ROOT` moves

src/bun/notes.fs.test.ts

@@ -80,6 +80,26 @@ beforeEach(async () => {
 });
 
 describe("createNote / writeNote / readNote", () => {
+  test("Korean headings name files and duplicate headings enumerate without clobbering", async () => {
+    const a = await createNote(ROOT, "# 한국어 제목\n\n첫 번째");
+    const b = await createNote(ROOT, "# 한국어 제목\n\n두 번째");
+    expect(a.path).toBe(join(ROOT, "한국어-제목.md"));
+    expect(b.path).toBe(join(ROOT, "한국어-제목-2.md"));
+    expect(a.title).toBe("한국어 제목");
+    expect(await textAt(a.path)).toBe("# 한국어 제목\n\n첫 번째");
+    expect(await textAt(b.path)).toBe("# 한국어 제목\n\n두 번째");
+  });
+
+  // Finder writes Korean names decomposed (NFD). On APFS that is the same file
+  // as the composed name slugify emits, so writing there would replace it.
+  test("a note beside a decomposed same-titled file does not overwrite it", async () => {
+    const existing = join(ROOT, "회의록.md".normalize("NFD"));
+    await writeRaw(existing, "# 회의록\n\nolder");
+    const made = await createNote(ROOT, "# 회의록\n\nnewer");
+    expect(made.path).toBe(join(ROOT, "회의록-2.md"));
+    expect(await textAt(existing)).toBe("# 회의록\n\nolder");
+  });
+
   test("names the file from the note's H1 and round-trips its text", async () => {
     const note = await createNote(ROOT, "# Shipping Notes\n\nhello");
     expect(note.path).toBe(join(ROOT, "shipping-notes.md"));
@@ -476,6 +496,29 @@ describe("notesTagged", () => {
 });
 
 describe("retitleNote", () => {
+  test("an untitled note can be renamed to a Korean heading", async () => {
+    const note = await createNote(ROOT, "본문");
+    const moved = await retitleNote(note.path, "# 한국어 제목\n\n본문");
+    expect(moved.path).toBe(join(ROOT, "한국어-제목.md"));
+    expect(await textAt(moved.path)).toBe("본문");
+    expect(await textAt(note.path)).toBeNull();
+  });
+
+  test("a retitle onto a decomposed file's name does not overwrite it", async () => {
+    const existing = join(ROOT, "회의록.md".normalize("NFD"));
+    await writeRaw(existing, "# 회의록\n\nolder");
+    const note = await createNote(ROOT, "draft");
+    const moved = await retitleNote(note.path, "# 회의록\n\ndraft");
+    expect(moved.path).toBe(join(ROOT, "회의록-2.md"));
+    expect(await textAt(existing)).toBe("# 회의록\n\nolder");
+  });
+
+  test("a decomposed file already named for its heading stays put", async () => {
+    const existing = join(ROOT, "회의록.md".normalize("NFD"));
+    await writeRaw(existing, "# 회의록\n");
+    expect((await retitleNote(existing, "# 회의록\n")).path).toBe(existing);
+  });
+
   test("moves the file to match its heading", async () => {
     const note = await createNote(ROOT, "# Draft\n");
     const moved = await retitleNote(note.path, "# Final\n");

src/bun/notes.ts

@@ -21,7 +21,7 @@ import { collectHits, type SearchHit } from "../shared/search";
 import { resolveWikiTitle, wikiRefsOf } from "../shared/wikilinks";
 import { normalizeTag, tagDirectoryOf, tagRefsOf, type TagInfo } from "../shared/tags";
 import { loadIgnore } from "./ignore";
-import { assertRegisteredRoot, assertWritableRoot, GITIGNORE, isInside, kindOf, rootContaining, uniqueName } from "./workspaces";
+import { assertRegisteredRoot, assertWritableRoot, GITIGNORE, isInside, kindOf, nameKey, rootContaining, uniqueName } from "./workspaces";
 import {
   beginPassphraseChange,
   commitPassphraseChange,
@@ -74,9 +74,8 @@ export { titleOf };
 
 // The filename a note's text asks for: its first-line H1 as a slug, or
 // "untitled" when the note has no usable heading. Bun slugs the heading itself
-// rather than taking a name from the view. slugify emits only [a-z0-9-], so
-// there is no name to validate and no way for the view to ask for a path
-// (architecture.md §2).
+// rather than taking a name from the view. slugify never emits a dot or a path
+// separator, so the view cannot ask for a path (architecture.md §2).
 function baseFor(text: string): string {
   return slugOf(text) ?? "untitled";
 }
@@ -1271,7 +1270,7 @@ export async function retitleNote(path: string, text: string): Promise<NoteMeta>
   for (const name of reserved) taken.add(name);
 
   const name = uniqueName(baseFor(text), taken);
-  if (name.toLowerCase() === current.toLowerCase()) {
+  if (nameKey(name) === nameKey(current)) {
     // Already correctly named, or uniqueName landed back on its own name.
     return metaFor(path, text);
   }

src/bun/workspaces.fs.test.ts

@@ -98,6 +98,10 @@ describe("createManaged", () => {
     expect(rules).toEqual([".ledge-trash/", ".*.md.tmp-*", ".DS_Store"]);
   });
 
+  test("a Korean display name creates a Korean workspace folder", async () => {
+    expect(await createManaged("한국어 노트")).toBe(join(resolve(APP_HOME), "한국어-노트"));
+  });
+
   test("a name that slugs to nothing falls back rather than failing", async () => {
     const root = await createManaged("???");
     expect(root).toBe(join(resolve(APP_HOME), "workspace"));

src/bun/workspaces.test.ts

@@ -19,6 +19,12 @@ describe("uniqueName", () => {
     expect(uniqueName("notes", new Set(["Notes.md", "notes-2.MD"]))).toBe("notes-3.md");
   });
 
+  // APFS also treats composed and decomposed spellings as one file, and Finder
+  // writes Korean names decomposed (NFD) while slugify emits NFC.
+  test("comparison ignores Unicode normalization, so an NFD name counts as taken", () => {
+    expect(uniqueName("회의록", new Set(["회의록.md".normalize("NFD")]))).toBe("회의록-2.md");
+  });
+
   test("suffixes from 2 upward, skipping every taken name", () => {
     const taken = new Set(["untitled.md", "untitled-2.md", "untitled-3.md"]);
     expect(uniqueName("untitled", taken)).toBe("untitled-4.md");

src/bun/workspaces.ts

@@ -32,7 +32,7 @@ export const WORKSPACES_PATH = join(APP_HOME, ".workspaces.json");
 // .workspaces.json, and every mutating seam in notes.ts and assets.ts refuses
 // it by calling assertWritableRoot below. The name is dotted and
 // .ledge-prefixed like every app-owned entry, so it cannot collide with a
-// managed workspace slug (slugify emits only [a-z0-9-], never a leading dot).
+// managed workspace slug (slugify never emits a leading dot).
 export const DOCS_ROOT = join(APP_HOME, ".ledge-docs");
 
 // The ignore file a new managed workspace is seeded with, so that `git init`
@@ -70,17 +70,23 @@ export function isInside(root: string, p: string): boolean {
 
 // Allocate a filename not already in `taken`: shipping-notes.md,
 // shipping-notes-2.md, and so on (with ext "", a workspace folder name).
-// Comparison is case-insensitive because macOS's default APFS is: "Foo.md" and
-// "foo.md" are one file there, so a case-sensitive check would return a name
-// whose rename overwrites the other note. On Linux it only means an extra
-// foo-2.md where foo.md was free.
+// Comparison ignores case and Unicode normalization because macOS's default
+// APFS does: "Foo.md" and "foo.md" are one file there, and so are a composed
+// "회의록.md" and the decomposed one Finder writes. A stricter check would
+// return a name whose rename overwrites the other note. On Linux it only means
+// an extra foo-2.md where foo.md was free.
 export function uniqueName(base: string, taken: Set<string>, ext = ".md"): string {
-  const lower = new Set([...taken].map((t) => t.toLowerCase()));
+  const keys = new Set([...taken].map(nameKey));
   let name = `${base}${ext}`;
-  for (let n = 2; lower.has(name.toLowerCase()); n += 1) name = `${base}-${n}${ext}`;
+  for (let n = 2; keys.has(nameKey(name)); n += 1) name = `${base}-${n}${ext}`;
   return name;
 }
 
+// The form two names share when APFS treats them as one file (uniqueName).
+export function nameKey(name: string): string {
+  return name.normalize("NFC").toLowerCase();
+}
+
 // The roots a loosely-spelled workspace name could mean: a root path (~
 // expands), or the folder name of a registered root as shorthand. The CLI's
 // --workspace argument (cli.ts resolveWorkspaceArg) and the daily.workspace
@@ -349,11 +355,10 @@ export async function ensureDefault(): Promise<string | null> {
 }
 
 // Creates a managed workspace folder from a display name. Bun slugs the name
-// itself, the same trust move as noteCreate: slugify emits only [a-z0-9-], so
-// the view has no path to smuggle through. uniqueName allocates the folder name
-// against a readdir snapshot of APP_HOME, so the mkdir cannot land on something
-// that exists. settings.jsonc, dot-entries, and squatting files all count as
-// taken.
+// itself, the same trust move as noteCreate: slugify never emits a dot or a
+// path separator, so the view has no path to smuggle through. uniqueName
+// allocates against a readdir snapshot of APP_HOME, including settings.jsonc,
+// dot-entries and squatting files, so mkdir cannot land on something that exists.
 export async function createManaged(name: string): Promise<string> {
   await ensureAppHome();
   const base = slugify(name) ?? "workspace";

src/shared/slug.test.ts

@@ -103,7 +103,53 @@ describe("slugify", () => {
     // The caller falls back to the enumerated "untitled" name.
     expect(slugify("!!!")).toBeNull();
     expect(slugify("   ")).toBeNull();
-    expect(slugify("日本語")).toBeNull();
+    expect(slugify("🎉")).toBeNull();
+  });
+
+  test("Korean and mixed-language headings keep their letters", () => {
+    expect(slugify("한국어 제목")).toBe("한국어-제목");
+    expect(slugify("Ledge 한국어 노트 2026")).toBe("ledge-한국어-노트-2026");
+    expect(slugify("日本語")).toBe("日本語");
+  });
+
+  test("decomposed Hangul produces the same composed filename", () => {
+    expect(slugify("한국어 제목".normalize("NFD"))).toBe("한국어-제목");
+  });
+
+  // Only Latin letters lose their accents. Elsewhere a mark changes the letter
+  // or is part of the word.
+  test("marks outside Latin script are kept, and the result is composed", () => {
+    expect(slugify("ガイド")).toBe("ガイド");
+    expect(slugify("ガイド".normalize("NFD"))).toBe("ガイド".normalize("NFC"));
+    expect(slugify("हिन्दी नोट्स")).toBe("हिन्दी-नोट्स");
+    expect(slugify("Мой план")).toBe("мой-план");
+    expect(slugify("Tiếng Việt")).toBe("tieng-viet");
+  });
+
+  test("a mark with no letter before it is dropped with the separator", () => {
+    expect(slugify("́abc")).toBe("abc");
+    expect(slugify("가 ́나")).toBe("가-나");
+  });
+
+  test("Unicode headings still remove unsafe path characters", () => {
+    expect(slugify("../../한국어/제목\\초안:메모\u0000")).toBe("한국어-제목-초안-메모");
+  });
+
+  // The temp file a save writes is the longest name a slug is part of
+  // (notes.ts writeNote), and ext4 refuses a name over 255 bytes.
+  test("long Unicode headings fit the filename limit without splitting a letter", () => {
+    expect(slugify("한".repeat(200))).toBe("한".repeat(60));
+    const slug = slugify("𠀀".repeat(200))!;
+    expect(slug).toBe("𠀀".repeat(50));
+    const temp = `.${slug}-99.md.tmp-4194304-4294967295`;
+    expect(new TextEncoder().encode(temp).length).toBeLessThanOrEqual(255);
+  });
+
+  test("truncation never separates a letter from its marks", () => {
+    // 60 code points end on ह, whose vowel sign ि is the 61st.
+    expect(slugify(`क${"हि".repeat(40)}`)).toBe(`क${"हि".repeat(29)}`);
+    // A letter buried under marks has nothing left once they are kept whole.
+    expect(slugify(`क${"́".repeat(150)}`)).toBeNull();
   });
 
   test("the slug is safe by construction: no dots, separators, or leading dot", () => {
@@ -130,6 +176,7 @@ describe("slugify", () => {
 describe("slugOf", () => {
   test("a titled note asks for its heading's slug", () => {
     expect(slugOf("# Shipping Notes\n\nbody")).toBe("shipping-notes");
+    expect(slugOf("# 한국어 제목\n\n본문")).toBe("한국어-제목");
   });
 
   test("an untitled note asks for nothing", () => {

src/shared/slug.ts

@@ -10,10 +10,12 @@
 // Renaming is safe only while a note's identity is its docId and not its path
 // (architecture.md §4).
 
-// Long enough for a real heading, short enough to stay clear of the 255-byte
-// filename limit every filesystem here shares, with room for a "-2" suffix and
-// the extension.
+// A slug is at most 60 code points and at most 200 UTF-8 bytes. The longest
+// name built from one is a save's temp file (".<slug>-2.md.tmp-<pid>-<n>",
+// notes.ts writeNote), about 30 bytes more, and ext4 refuses a name over 255
+// bytes. Hangul and kanji fit all 60; 4-byte letters stop at 50.
 const MAX_SLUG = 60;
+const MAX_SLUG_BYTES = 200;
 
 // Far longer than any real heading, short enough that a runaway one cannot
 // bloat the store. Only the on-screen label is capped; the note's text is
@@ -44,26 +46,38 @@ export function headingOf(text: string): string | null {
 }
 
 // Turns a heading into a filesystem-safe slug, or null if nothing usable is
-// left. Everything outside [a-z0-9] becomes a separator, which makes the
-// result safe by construction: no dots, no slashes, no colons, no control
-// characters, no leading dot. This is the whole trust boundary for a name
-// arriving from the view (architecture.md §2).
+// left. Everything outside Unicode letters, their combining marks and numbers
+// becomes a separator: no dots, no slashes, no colons, no control characters,
+// no leading dot. The result is NFC. This is the whole trust boundary for a
+// name arriving from the view (architecture.md §2).
 export function slugify(heading: string): string | null {
-  // Fold accents first ("Café" -> "cafe"). Otherwise each accented letter
-  // becomes a separator and breaks the word into pieces.
-  const folded = heading.normalize("NFD").replace(/\p{M}/gu, "");
-  const slug = folded
+  // Fold accents off Latin letters ("Café" -> "cafe"), so a Latin heading
+  // names an ASCII file. Other scripts keep their marks: が is not か, and a
+  // Devanagari vowel sign is part of the word. NFC recomposes what NFD split.
+  const folded = heading
+    .normalize("NFD")
+    .replace(/(\p{Script=Latin})\p{M}+/gu, "$1")
     .toLowerCase()
-    .replace(/[^a-z0-9]+/g, "-")
-    .replace(/^-+|-+$/g, "");
-  if (!slug) return null; // a heading of pure punctuation or non-latin script
-  if (slug.length <= MAX_SLUG) return slug;
+    .normalize("NFC");
+  // A mark with no letter before it goes with the separator it follows.
+  const slug = folded.replace(/^\p{M}+|[^\p{L}\p{M}\p{N}]+\p{M}*/gu, "-").replace(/^-+|-+$/g, "");
+  if (!slug) return null; // a heading of pure punctuation
+  const chars = Array.from(slug);
+  if (chars.length <= MAX_SLUG && utf8Length(slug) <= MAX_SLUG_BYTES) return slug;
+  const cut = chars.slice(0, MAX_SLUG);
+  while (utf8Length(cut.join("")) > MAX_SLUG_BYTES) cut.pop();
+  // Never cut between a letter and its marks.
+  while (cut.length > 0 && /\p{M}/u.test(chars[cut.length] ?? "")) cut.pop();
   // Truncate on a word boundary when one is near the end, so a long heading is
   // cut at "shipping-notes" rather than "shipping-note".
-  const cut = slug.slice(0, MAX_SLUG);
   const lastDash = cut.lastIndexOf("-");
-  const trimmed = lastDash >= MAX_SLUG / 2 ? cut.slice(0, lastDash) : cut;
-  return trimmed.replace(/-+$/, "");
+  const trimmed = (lastDash >= cut.length / 2 ? cut.slice(0, lastDash) : cut).join("");
+  return trimmed.replace(/-+$/, "") || null;
+}
+
+const utf8 = new TextEncoder();
+function utf8Length(s: string): number {
+  return utf8.encode(s).length;
 }
 
 // The slug for a note's text, or null if it has no usable first-line H1. A note