The snap publish step calls a command snapcraft still has

.github/workflows/publish-packages.yml

@@ -173,4 +173,18 @@ jobs:
           SNAP_FILE="${snaps[0]}"
 
           gh release upload "$TAG" "$SNAP_FILE" --clobber
-          snapcraft push "$SNAP_FILE" --release stable
+
+          # `upload`, not `push`. snapcraft 8 turned the old name into a hard
+          # error -- "The 'push' command was renamed to 'upload'", exit 64 --
+          # and the step above installs whatever `snap install snapcraft
+          # --classic` currently serves, so the command this line calls stopped
+          # existing without a commit here.
+          #
+          # It last worked on 2026-06-03: markpad 2.6.11, revision 15, which is
+          # still what the Snap Store serves. Every run after that died earlier,
+          # in the build, and the swallowing this workflow's header describes
+          # reported it as success. #561 removed that and #577/#579 fixed the
+          # build, so v2.7.4 was the first release to reach this line -- and it
+          # failed here, in run 31775835301, after packing
+          # markpad_2.7.4_amd64.snap green.
+          snapcraft upload "$SNAP_FILE" --release stable

scripts/releaseWorkflow.test.ts

@@ -273,10 +273,18 @@ test('a package manager is not published from inside the platform matrix', () =>
 	// Matched on the push commands rather than on step names, because the
 	// property is "the build matrix has no irreversible external effect", and a
 	// renamed step would still have one.
+	//
+	// `snapcraft upload` was `snapcraft push` here until snapcraft 8 removed
+	// that name. Worth being honest about what this assertion is: it pins the
+	// string the workflow uses, so it went on passing for the whole time the
+	// command it named did not exist. Nothing runnable from `npm test` can
+	// check the other half -- the tool is installed by the job, from the store,
+	// at release time. See publish-packages.yml.
+	assert.doesNotMatch(workflow, /snapcraft (pack|push|upload)/);
 	assert.doesNotMatch(workflow, /choco push/);
-	assert.doesNotMatch(workflow, /snapcraft (pack|push)/);
 	assert.match(publishWorkflow, /choco push/);
-	assert.match(publishWorkflow, /snapcraft push/);
+	assert.match(publishWorkflow, /snapcraft upload/);
+	assert.doesNotMatch(publishWorkflow, /snapcraft push/);
 });
 
 test('package managers are published from a release a human published', () => {
@@ -418,7 +426,7 @@ test('the package managers we recommend are the ones we publish to', () => {
 	const releaseBody = sliceBetween(workflow, "echo '## Download'", 'RELEASE_BODY');
 	for (const [name, install, push] of [
 		['Chocolatey', /choco install markpad-app/, /choco push/],
-		['Snap', /snap install markpad/, /snapcraft push/],
+		['Snap', /snap install markpad/, /snapcraft upload/],
 	] as const) {
 		const publishes = push.test(publishWorkflow);
 		assert.equal(

snapcraft.yaml

@@ -28,6 +28,7 @@ website: https://markpad.sftwr.dev
 donation: https://github.com/sponsors/alecdotdev
 source-code: https://github.com/sftwrdotdev/Markpad
 issues: https://github.com/sftwrdotdev/Markpad/issues
+contact: https://github.com/sftwrdotdev/Markpad/issues
 
 confinement: strict
 base: core24
@@ -44,6 +45,12 @@ apps:
       - network-bind
       - wayland
       - home
+      # `home` reaches $HOME and nothing else, so a note kept on a USB stick or
+      # a second-drive mount is invisible to the app, with no way for the user
+      # to grant it. This does not auto-connect -- it takes one
+      # `sudo snap connect markpad:removable-media` -- but without the plug
+      # declared here there is nothing to connect. #562.
+      - removable-media
 
 parts:
   # The snap packages the .deb the release already shipped. It does not build