diff --git a/net-im/mattermost-desktop-bin/Manifest b/net-im/mattermost-desktop-bin/Manifest
index aa6481bb14293..b5924fc85d5bc 100644
--- a/net-im/mattermost-desktop-bin/Manifest
+++ b/net-im/mattermost-desktop-bin/Manifest
@@ -4,3 +4,5 @@ DIST mattermost-desktop-6.2.2-linux-arm64.tar.gz 117886439 BLAKE2B f4b4eee6e20ce
 DIST mattermost-desktop-6.2.2-linux-x64.tar.gz 117833492 BLAKE2B 57ab6eff042c7f2d1c898d6c14296068d86c3fd1caf9d8d40be1f448f8b86885de6b55c6be4851225d8f3aa2152b67ca2beab802eb2ee5320b009bf9fa24cd91 SHA512 226d6fa2e1ffb75a4938a0b9cfb5f610b43e30a423ebbe6642a8df54de3ae7ca5de7b20de3b0309b4460cd29e49a91e9cf41050c88c92835245b191f84cf8d95
 DIST mattermost-desktop-6.3.0-rc.2-linux-arm64.tar.gz 126597234 BLAKE2B c3dbeb5ef1080bb2b72e861636d1ad52ef6c8a2b924fc82ef72155b50527ad9ae9e97a3618f53a0ba8678f78c64a356f07665b4039546a670df01a4376ed32b9 SHA512 414a9691aee870ba6258e4089a351e2abbd7dc1de4ef522a0372e14a1684c3ebdeb503c973802a77d29f8b51e654637b061161577725247587f917c0ceeb5193
 DIST mattermost-desktop-6.3.0-rc.2-linux-x64.tar.gz 127748526 BLAKE2B 4a87110a658c77550ded353b3acf3b5e900e0475819a4e56f7d09a12624b2b782b24f888fb8df9bbf213f71ee9f61d83982a679686aa75be8e180aec14176b58 SHA512 e4bb9401363789586b218a12212dd7828c225f8b9ecad805da523373eae6faa6f7d28465b0147621c9cfd04b505cb775745bbc9ff0dcdc377fa9e6dcc61711fc
+DIST mattermost-desktop-6.3.0-rc.3-linux-arm64.tar.gz 126598087 BLAKE2B 7d4030dc5656210065b589b26c79e907817713083115842ca06a3994baa0161c9d38d20fbe75ec8fd57bdd77249d2a830d07cedb0afea9ee609fa3459edbb361 SHA512 278771b8db92d7ed155d021614b4fec562fc6049222c81ee634080f13b851ce411bc653dd742a307d12b3bd8b430e970cd1541f50ce5d0f4a043cd3a1fc20421
+DIST mattermost-desktop-6.3.0-rc.3-linux-x64.tar.gz 127749350 BLAKE2B ca2f5603f5062aa720ce6ef8a062e1b19a636a16d3d0e9ad816ec6997ae6542f622ff3f871b6d9f9119787e5f1e509ff557a0b9027232f63bf7fbf2c0954c82e SHA512 64a57571fa98bf6c987001b94145b83dd6928fa8b158f57489bb23d7ced6104b909c979038e8ebaa89376ad743d844f4fabd700ed4367d8f83a9d570a4ff4d36
diff --git a/net-im/mattermost-desktop-bin/mattermost-desktop-bin-6.3.0_rc3.ebuild b/net-im/mattermost-desktop-bin/mattermost-desktop-bin-6.3.0_rc3.ebuild
new file mode 100644
index 0000000000000..717bc6a945b1d
--- /dev/null
+++ b/net-im/mattermost-desktop-bin/mattermost-desktop-bin-6.3.0_rc3.ebuild
@@ -0,0 +1,123 @@
+# Copyright 1999-2026 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+MY_PN="${PN%-*}"
+MY_PV="${PV/_rc/-rc.}"
+
+inherit desktop toolchain-funcs xdg
+
+DESCRIPTION="Mattermost Desktop application"
+HOMEPAGE="https://mattermost.com/"
+
+SRC_URI="
+	amd64? ( https://releases.mattermost.com/desktop/${MY_PV}/mattermost-desktop-${MY_PV}-linux-x64.tar.gz )
+	arm64? ( https://releases.mattermost.com/desktop/${MY_PV}/mattermost-desktop-${MY_PV}-linux-arm64.tar.gz )
+"
+S="${WORKDIR}"
+
+LICENSE="Apache-2.0 GPL-2+ LGPL-2.1+ MIT"
+SLOT="0"
+if [[ ${PV} != *rc* ]]; then
+	KEYWORDS="~amd64 ~arm64"
+fi
+
+RDEPEND="
+	>=app-accessibility/at-spi2-core-2.46.0:2[X]
+	dev-libs/expat
+	dev-libs/glib:2
+	dev-libs/nspr
+	dev-libs/nss
+	dev-libs/wayland
+	media-libs/alsa-lib
+	media-libs/mesa
+	net-print/cups
+	sys-apps/dbus
+	sys-libs/glibc
+	virtual/libudev
+	x11-libs/cairo
+	x11-libs/gdk-pixbuf:2
+	x11-libs/gtk+:3[X]
+	x11-libs/libX11
+	x11-libs/libXcomposite
+	x11-libs/libXdamage
+	x11-libs/libXext
+	x11-libs/libXfixes
+	x11-libs/libXrandr
+	x11-libs/libdrm
+	x11-libs/libxcb
+	x11-libs/libxkbcommon
+	x11-libs/pango
+"
+
+BDEPEND="
+	dev-util/debugedit
+"
+
+QA_PREBUILT="
+	opt/mattermost-desktop/mattermost-desktop
+	opt/mattermost-desktop/chrome_crashpad_handler
+	opt/mattermost-desktop/libnode.so
+	opt/mattermost-desktop/libffmpeg.so
+	opt/mattermost-desktop/libGLESv2.so
+	opt/mattermost-desktop/libEGL.so
+	opt/mattermost-desktop/libvk_swiftshader.so
+	opt/mattermost-desktop/libvulkan.so.1
+	opt/mattermost-desktop/resources/*
+"
+
+DOCS=(
+	NOTICE.txt
+)
+
+src_prepare() {
+	default
+
+	if use amd64; then
+		find . '(' -name koffi-linux-arm64 -o -name musl_x64 ')' -exec rm -r {} + || die
+	elif use arm64; then
+		find . '(' -name koffi-linux-x64 -o name musl_arm64 ')' -exec rm -r {} + || die
+	fi
+
+	# file collision with FEATURES=splitdebug, see bug #961437
+	tc-export OBJCOPY
+	find . -type f ! -name '*$(*)*' -print0 | while IFS= read -r -d '' file; do
+		if file "${file}" | grep -qE "ELF (32|64)-bit"; then
+			${OBJCOPY} --remove-section .note.gnu.build-id "${file}" || die
+			debugedit -b "${EPREFIX}/opt/${MY_PN}" -d "/usr/lib/debug" -i "${file}" || die
+		fi
+	done
+}
+
+src_install() {
+	if use amd64; then
+		cd mattermost-desktop-${MY_PV}-linux-x64 || die
+	elif use arm64; then
+		cd mattermost-desktop-${MY_PV}-linux-arm64 || die
+	fi
+	newicon app_icon.png ${MY_PN}.png
+
+	insinto "/opt/${MY_PN}/locales"
+	doins locales/*.pak
+
+	insinto "/opt/${MY_PN}/resources"
+	doins -r resources/*.asar*
+
+	insinto "/opt/${MY_PN}"
+	doins *.pak *.bin *.dat
+	exeinto "/opt/${MY_PN}"
+	doexe *.so *.so.* "${MY_PN}" chrome_crashpad_handler
+
+	dosym -r "/opt/${MY_PN}/${MY_PN}" "/usr/bin/${MY_PN}"
+
+	make_desktop_entry --eapi9 mattermost-desktop \
+		-a "--enable-features=WaylandWindowDecorations --ozone-platform-hint=auto %U" \
+		-d Mattermost.Desktop \
+		-n Mattermost \
+		-i mattermost-desktop \
+		-c "Network;InstantMessaging;" \
+		-e "MimeType=x-scheme-handler/mattermost;" -e "StartupWMClass=Mattermost.Desktop"
+
+	einstalldocs
+}