From f9d158731b5a5f3ab02d5d9140dfcac9dbd59c4b Mon Sep 17 00:00:00 2001
From: Mark Pitman <mark@pitman.io>
Date: Tue, 13 Oct 2026 21:48:00 -0700
Subject: [PATCH] Move the snap to core24 and replace the unity7 plug

Use the desktop plug instead of the transitional unity7 plug. Both let xdg-open reach snapd's launcher service (checked in snapd's interface definitions), and desktop is the interface unity7 duplicates that access from.

snapd points HOME at the snap's private data directory, which is why the snap forced HOME to /home/$USER. Read SNAP_REAL_HOME for ~/mdview-temp instead, and drop the override. It falls back to HOME outside that case.

Move to base core24, which needs platforms in place of architectures.

Closes #72
---
 CLAUDE.md           |  6 +++++-
 main.go             |  7 ++++++-
 main_test.go        | 13 +++++++++++++
 snap/snapcraft.yaml | 17 ++++++-----------
 4 files changed, 30 insertions(+), 13 deletions(-)

diff --git a/CLAUDE.md b/CLAUDE.md
index 1c10d43..975cd9d 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -45,7 +45,11 @@ Everything happens in `main()` in `main.go`, in a straight-line pipeline:
 
 ### Temp file / Snap sandboxing (`getTempDir`, `isSnap`)
 
-Output location resolution order: `MDVIEW_DIR` env var → (if running as a Snap, per `SNAP_USER_COMMON` env var) `~/mdview-temp` → OS default temp dir. `MDVIEW_DIR` and `~/mdview-temp` are created with `MkdirAll`. Before writing a temp file, `removeStaleTempFiles` deletes generated `mdview<32 hex>.html` files older than 24 hours from that directory (the browser reads the new file after mdview exits, so mdview cannot delete it right away). This exists because Snap-sandboxed browsers (e.g. Snap Firefox) can't read from `/tmp`, only from the user's home directory — `check()` writes errors to stderr, names the failing path, and prints a Snap-specific hint for permission and not-found errors for this reason.
+Output location resolution order: `MDVIEW_DIR` env var → (if running as a Snap, per `SNAP_USER_COMMON` env var) `~/mdview-temp` (the home directory comes from `SNAP_REAL_HOME`, because snapd remaps `HOME` to the snap's private data directory) → OS default temp dir. `MDVIEW_DIR` and `~/mdview-temp` are created with `MkdirAll`. Before writing a temp file, `removeStaleTempFiles` deletes generated `mdview<32 hex>.html` files older than 24 hours from that directory (the browser reads the new file after mdview exits, so mdview cannot delete it right away). This exists because Snap-sandboxed browsers (e.g. Snap Firefox) can't read from `/tmp`, only from the user's home directory — `check()` writes errors to stderr, names the failing path, and prints a Snap-specific hint for permission and not-found errors for this reason.
+
+The snap (`snap/snapcraft.yaml`, `base: core24`, `platforms:` instead of `architectures:`) plugs `home` and
+`desktop`. `desktop` (auto-connected) lets `xdg-open` launch the default browser; it replaced the transitional
+`unity7` plug.
 
 ### Vendored `mermaid.min.js`
 
diff --git a/main.go b/main.go
index f673f91..49c1d12 100644
--- a/main.go
+++ b/main.go
@@ -243,7 +243,12 @@ func getTempDir() string {
 	}
 
 	if isSnap() {
-		var tmpdir = filepath.Join(os.Getenv("HOME"), "mdview-temp")
+		// snapd points HOME at the snap's private data directory, so use the real home directory
+		home := os.Getenv("SNAP_REAL_HOME")
+		if home == "" {
+			home = os.Getenv("HOME")
+		}
+		var tmpdir = filepath.Join(home, "mdview-temp")
 		check(os.MkdirAll(tmpdir, 0700))
 		return tmpdir
 	}
diff --git a/main_test.go b/main_test.go
index a807292..b5db254 100644
--- a/main_test.go
+++ b/main_test.go
@@ -325,6 +325,19 @@ func TestGetTempDir(t *testing.T) {
 		home := t.TempDir()
 		t.Setenv("MDVIEW_DIR", "")
 		t.Setenv("SNAP_USER_COMMON", "/snap/common")
+		t.Setenv("HOME", filepath.Join(home, "snap", "mdview", "1"))
+		t.Setenv("SNAP_REAL_HOME", home)
+		want := filepath.Join(home, "mdview-temp")
+		if got := getTempDir(); got != want {
+			t.Fatalf("getTempDir = %q, want %q", got, want)
+		}
+	})
+
+	t.Run("snap without SNAP_REAL_HOME falls back to HOME", func(t *testing.T) {
+		home := t.TempDir()
+		t.Setenv("MDVIEW_DIR", "")
+		t.Setenv("SNAP_USER_COMMON", "/snap/common")
+		t.Setenv("SNAP_REAL_HOME", "")
 		t.Setenv("HOME", home)
 		want := filepath.Join(home, "mdview-temp")
 		if got := getTempDir(); got != want {
diff --git a/snap/snapcraft.yaml b/snap/snapcraft.yaml
index ace6158..ad677b7 100644
--- a/snap/snapcraft.yaml
+++ b/snap/snapcraft.yaml
@@ -7,13 +7,11 @@ description: |
   Type `mdview --help` for options. https://github.com/mapitman/mdview
 grade: stable
 confinement: strict
-base: core22
+base: core24
 apps:
     mdview:
       command: bin/mdview
-      plugs: [home,unity7]
-      environment:
-        HOME: /home/$USER
+      plugs: [home, desktop]
 adopt-info: mdview
 parts:
   mdview:
@@ -29,10 +27,7 @@ parts:
     #   - libblkid-dev
     build-snaps:
       - go
-architectures:
-  - build-on: [amd64]
-    build-for: [amd64]
-  - build-on: [arm64]
-    build-for: [arm64]
-  - build-on: [armhf]
-    build-for: [armhf]
+platforms:
+  amd64:
+  arm64:
+  armhf: