diff --git a/src/gui/src/UI/Dashboard/shareAvatar.js b/src/gui/src/UI/Dashboard/shareAvatar.js
new file mode 100644
index 000000000..7a77bcb14
--- /dev/null
+++ b/src/gui/src/UI/Dashboard/shareAvatar.js
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2024-present Puter Technologies Inc.
+ *
+ * This file is part of Puter.
+ *
+ * Puter is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+// The initial-and-color avatar the share modal shows next to each person.
+
+/**
+ * Stable, name-derived hue so a person keeps the same color across reopenings.
+ *
+ * @param {string} [name]
+ * @returns {number} hue in [0, 360)
+ */
+export const avatarHue = (name) => {
+    let hue = 0;
+    for ( const char of String(name ?? '') ) {
+        hue = (hue * 31 + char.codePointAt(0)) % 360;
+    }
+    return hue;
+};
+
+/**
+ * The name's first character, uppercased; `?` when there is no name.
+ *
+ * @param {string} [name]
+ * @returns {string}
+ */
+export const avatarInitial = (name) => {
+    const trimmed = String(name ?? '').trim();
+    // Iterating takes a whole code point; charAt(0) halves an emoji into tofu.
+    for ( const char of trimmed ) return char.toUpperCase();
+    return '?';
+};
diff --git a/src/gui/src/UI/Dashboard/shareAvatar.test.js b/src/gui/src/UI/Dashboard/shareAvatar.test.js
new file mode 100644
index 000000000..75965dc53
--- /dev/null
+++ b/src/gui/src/UI/Dashboard/shareAvatar.test.js
@@ -0,0 +1,51 @@
+import { describe, expect, it } from 'vitest';
+import { avatarHue, avatarInitial } from './shareAvatar.js';
+
+describe('avatarHue', () => {
+    it('gives the same person the same color every time', () => {
+        expect(avatarHue('juan')).toBe(avatarHue('juan'));
+    });
+
+    it('stays a usable hue', () => {
+        for ( const name of ['a', 'juan', 'someone@example.com', '𝒥'.repeat(40)] ) {
+            const hue = avatarHue(name);
+            expect(Number.isInteger(hue)).toBe(true);
+            expect(hue).toBeGreaterThanOrEqual(0);
+            expect(hue).toBeLessThan(360);
+        }
+    });
+
+    it('tells different people apart', () => {
+        expect(avatarHue('ann')).not.toBe(avatarHue('bob'));
+    });
+
+    it('handles a missing name instead of throwing', () => {
+        expect(avatarHue(undefined)).toBe(0);
+        expect(avatarHue(null)).toBe(0);
+        expect(avatarHue('')).toBe(0);
+    });
+});
+
+describe('avatarInitial', () => {
+    it('uppercases the first letter', () => {
+        expect(avatarInitial('juan')).toBe('J');
+        expect(avatarInitial('Ann')).toBe('A');
+    });
+
+    it('ignores surrounding whitespace', () => {
+        expect(avatarInitial('  ann ')).toBe('A');
+    });
+
+    it('falls back to ? when there is no name', () => {
+        // A pending invite has no username until the recipient joins.
+        expect(avatarInitial('')).toBe('?');
+        expect(avatarInitial('   ')).toBe('?');
+        expect(avatarInitial(undefined)).toBe('?');
+        expect(avatarInitial(null)).toBe('?');
+    });
+
+    it('keeps an astral first character whole', () => {
+        // charAt(0) would return half a surrogate pair and render as tofu.
+        expect(avatarInitial('😀 team')).toBe('😀');
+    });
+});
diff --git a/src/gui/src/UI/UIWindowShare.js b/src/gui/src/UI/UIWindowShare.js
index 98f0de4b7..1f6986371 100644
--- a/src/gui/src/UI/UIWindowShare.js
+++ b/src/gui/src/UI/UIWindowShare.js
@@ -23,31 +23,7 @@ import path from '../lib/path.js';
 import { owner_of_path } from '../helpers/path_owner.js';
 import { invalidate_shared_roots } from '../helpers/shared_access.js';
 import { icons } from '../helpers/actionIcons.js';
-
-// Offered when granting. The API accepts `see` and `list` too, but they are a
-// developer-level distinction with no place in this dialog — a row already set
-// to one is shown as-is rather than quietly rounded up to `read`.
-const MODES = ['read', 'write', 'manage'];
-
-// Already HTML-safe: `i18n()` encodes what it returns, and an unencoded mode
-// from the API is encoded here. Encoding a label again turns the `&` in
-// "Can edit & share" into a literal `&amp;`.
-const mode_label = (mode) => {
-    if ( mode === 'write' ) return i18n('share_access_write');
-    if ( mode === 'manage' ) return i18n('share_access_manage');
-    if ( mode === 'read' ) return i18n('share_access_read');
-    return html_encode(mode);
-};
-
-const options_for = (current) => {
-    const modes = MODES.includes(current) ? MODES : [current, ...MODES];
-    return modes
-        .map(
-            (mode) =>
-                `<option value="${html_encode(mode)}"${mode === current ? ' selected' : ''}>${mode_label(mode)}</option>`,
-        )
-        .join('');
-};
+import { mode_label, options_for } from '../helpers/share_modes.js';
 
 /**
  * Sharing dialog for one file or directory.
diff --git a/src/gui/src/helpers/share_modes.js b/src/gui/src/helpers/share_modes.js
new file mode 100644
index 000000000..5261a9cd3
--- /dev/null
+++ b/src/gui/src/helpers/share_modes.js
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2024-present Puter Technologies Inc.
+ *
+ * This file is part of Puter.
+ *
+ * Puter is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+// Access levels the sharing dialogs offer, shared so the two can't drift.
+
+// The API also accepts `see` and `list`, a developer-level distinction with no
+// place in these dialogs; a row already set to one is shown as-is.
+export const MODES = ['read', 'write', 'manage'];
+
+/**
+ * Human-readable label for an access mode, ready to drop into HTML.
+ *
+ * Already HTML-safe — encoding it again renders the `&` in "Can edit & share".
+ *
+ * @param {string} mode
+ * @returns {string} HTML-safe label
+ */
+export const mode_label = (mode) => {
+    if ( mode === 'write' ) return i18n('share_access_write');
+    if ( mode === 'manage' ) return i18n('share_access_manage');
+    if ( mode === 'read' ) return i18n('share_access_read');
+    return html_encode(mode);
+};
+
+/**
+ * `<option>` markup for a mode `<select>`, with `current` selected.
+ *
+ * A mode outside `MODES` is listed first rather than dropped, so opening a
+ * dialog on a `see`/`list` grant doesn't silently rewrite it.
+ *
+ * @param {string} current
+ * @returns {string} HTML-safe markup
+ */
+export const options_for = (current) => {
+    const modes = MODES.includes(current) ? MODES : [current, ...MODES];
+    return modes
+        .map(
+            (mode) =>
+                `<option value="${html_encode(mode)}"${mode === current ? ' selected' : ''}>${mode_label(mode)}</option>`,
+        )
+        .join('');
+};
diff --git a/src/gui/src/helpers/share_modes.test.js b/src/gui/src/helpers/share_modes.test.js
new file mode 100644
index 000000000..4c594e03c
--- /dev/null
+++ b/src/gui/src/helpers/share_modes.test.js
@@ -0,0 +1,70 @@
+import { beforeAll, describe, expect, it } from 'vitest';
+import { decode, encode } from 'html-entities';
+
+// Runs the real `i18n` and the real encoder, like UIPermissionDialog.rendering.test.js:
+// a stubbed i18n echoes keys and cannot tell single- from double-encoding.
+globalThis.window = globalThis.window ?? {};
+globalThis.html_encode = (str) => encode(str);
+
+let MODES, mode_label, options_for;
+
+beforeAll(async () => {
+    await import('../i18n/i18n.js'); // installs window.i18n
+    globalThis.i18n = window.i18n;
+    ({ MODES, mode_label, options_for } = await import('./share_modes.js'));
+});
+
+// What the browser renders for a fragment of HTML-safe markup.
+const as_text = (html) => decode(html);
+
+describe('mode_label', () => {
+    it('encodes exactly once, so "&" survives as "&"', () => {
+        const label = mode_label('manage');
+        expect(label).toBe('Can edit &amp; share');
+        expect(as_text(label)).toBe('Can edit & share');
+        // The bug this guards: encoding an already-encoded label again.
+        expect(label).not.toContain('&amp;amp;');
+    });
+
+    it('labels the modes the dialogs offer', () => {
+        expect(as_text(mode_label('read'))).toBe('Can view');
+        expect(as_text(mode_label('write'))).toBe('Can edit');
+    });
+
+    it('shows an out-of-band mode as-is', () => {
+        expect(mode_label('see')).toBe('see');
+        expect(mode_label('list')).toBe('list');
+    });
+
+    it('encodes an unrecognized mode rather than trusting it', () => {
+        expect(mode_label('<img src=x onerror=alert(1)>')).not.toContain('<img');
+    });
+});
+
+describe('options_for', () => {
+    const values = (html) => [...html.matchAll(/value="([^"]*)"/g)].map((m) => m[1]);
+
+    it('offers the three modes with the current one selected', () => {
+        const html = options_for('read');
+        expect(values(html)).toEqual(MODES);
+        expect(html).toContain('<option value="read" selected>');
+    });
+
+    it('selects a non-default mode without reordering', () => {
+        const html = options_for('manage');
+        expect(values(html)).toEqual(MODES);
+        expect(html).toContain('<option value="manage" selected>');
+        expect(html).not.toContain('<option value="read" selected>');
+    });
+
+    it('keeps an out-of-band mode instead of rounding it to read', () => {
+        const html = options_for('see');
+        expect(values(html)).toEqual(['see', ...MODES]);
+        expect(html).toContain('<option value="see" selected>');
+    });
+
+    it('renders each label encoded exactly once', () => {
+        expect(options_for('read')).toContain('>Can edit &amp; share</option>');
+        expect(options_for('read')).not.toContain('&amp;amp;');
+    });
+});