diff --git a/scripts/instance-env.sh b/scripts/instance-env.sh
index bc185d98f18..f926c74dc31 100755
--- a/scripts/instance-env.sh
+++ b/scripts/instance-env.sh
@@ -39,8 +39,14 @@ if git rev-parse --is-inside-work-tree &>/dev/null; then
     GIT_COMMON_DIR=$(git rev-parse --git-common-dir 2>/dev/null)
     if [[ -n "$GIT_COMMON_DIR" && "$GIT_DIR" != "$GIT_COMMON_DIR" ]]; then
         BRANCH_NAME=$(git rev-parse --abbrev-ref HEAD)
-        export BUZZ_WORKTREE_LABEL="${BRANCH_NAME##*/}"
-        export BUZZ_INSTANCE_SLUG=$(echo "$BRANCH_NAME" | tr '[:upper:]' '[:lower:]' | sed 's/[^a-z0-9]/-/g' | sed 's/--*/-/g' | sed 's/^-//' | sed 's/-$//')
+        export BUZZ_WORKTREE_LABEL="${BUZZ_DEV_LABEL:-${BRANCH_NAME##*/}}"
+        INSTANCE_IDENTITY="${BUZZ_DEV_LABEL:-$BRANCH_NAME}"
+        export BUZZ_INSTANCE_SLUG=$(echo "$INSTANCE_IDENTITY" | tr '[:upper:]' '[:lower:]' | sed 's/[^a-z0-9]/-/g' | sed 's/--*/-/g' | sed 's/^-//' | sed 's/-$//')
+        if [[ -z "$BUZZ_INSTANCE_SLUG" ]]; then
+            echo "BUZZ_DEV_LABEL must contain at least one letter or number" >&2
+            return 1 2>/dev/null || exit 1
+        fi
+        WORKTREE_PRODUCT_NAME=$(python3 -c 'import json,sys; print(json.dumps(f"Buzz Dev ({sys.argv[1]})"))' "$BUZZ_WORKTREE_LABEL")
 
         # BUZZ_SHARE_IDENTITY=1: reuse the main dev checkout's Nostr key so
         # worktrees skip onboarding and share the same identity. The per-worktree
@@ -89,7 +95,7 @@ if git rev-parse --is-inside-work-tree &>/dev/null; then
         if swift "$GENERATE_DEV_ICON" "$BASE_ICON" "$DEV_ICON" "$BUZZ_WORKTREE_LABEL"; then
             echo "🌳 Worktree: ${BUZZ_WORKTREE_LABEL}"
             export VITE_DEV_BRANCH="$BUZZ_WORKTREE_LABEL"
-            BUZZ_TAURI_CONFIG="{\"build\":{\"devUrl\":\"${DEV_URL}\",\"beforeDevCommand\":\"exec ./node_modules/.bin/vite --port ${BUZZ_VITE_PORT} --strictPort\"},\"identifier\":\"xyz.block.buzz.app.dev.${BUZZ_INSTANCE_SLUG}\",\"productName\":\"Buzz Dev (${BUZZ_WORKTREE_LABEL})\",\"bundle\":{\"icon\":[\"$DEV_ICON\"]}}"
+            BUZZ_TAURI_CONFIG="{\"build\":{\"devUrl\":\"${DEV_URL}\",\"beforeDevCommand\":\"exec ./node_modules/.bin/vite --port ${BUZZ_VITE_PORT} --strictPort\"},\"identifier\":\"xyz.block.buzz.app.dev.${BUZZ_INSTANCE_SLUG}\",\"productName\":${WORKTREE_PRODUCT_NAME},\"bundle\":{\"icon\":[\"$DEV_ICON\"]}}"
         fi
     fi
 fi
diff --git a/scripts/test-desktop-release-candidate.sh b/scripts/test-desktop-release-candidate.sh
index 503c64eb37d..4b8fa69120c 100755
--- a/scripts/test-desktop-release-candidate.sh
+++ b/scripts/test-desktop-release-candidate.sh
@@ -225,4 +225,6 @@ root_sha=$(git -C "$initial" rev-parse HEAD)
 grep -Fq "$root_sha" "$initial/CHANGELOG.md"
 rm -rf "$initial"
 
+"$repo_root/scripts/test-instance-env.sh"
+
 echo "desktop release candidate contract passed"
diff --git a/scripts/test-instance-env.sh b/scripts/test-instance-env.sh
new file mode 100755
index 00000000000..181d0faceb3
--- /dev/null
+++ b/scripts/test-instance-env.sh
@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repo_root=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+test_root=$(mktemp -d)
+trap 'rm -rf "$test_root"' EXIT
+
+mkdir -p "$test_root/bin" "$test_root/checkout/desktop/src-tauri/icons"
+touch "$test_root/checkout/desktop/src-tauri/icons/icon.icns"
+
+cat >"$test_root/bin/git" <<EOF
+#!/usr/bin/env bash
+case "\$*" in
+  "rev-parse --show-toplevel") printf '%s\n' '$test_root/checkout' ;;
+  "rev-parse --is-inside-work-tree") exit 0 ;;
+  "rev-parse --git-dir") printf '%s\n' '.git/worktrees/test' ;;
+  "rev-parse --git-common-dir") printf '%s\n' '.git' ;;
+  "rev-parse --abbrev-ref HEAD") printf '%s\n' 'HEAD' ;;
+  *) exit 1 ;;
+esac
+EOF
+chmod +x "$test_root/bin/git"
+
+cat >"$test_root/bin/swift" <<'EOF'
+#!/usr/bin/env bash
+mkdir -p "$(dirname "$3")"
+touch "$3"
+EOF
+chmod +x "$test_root/bin/swift"
+
+result=$(
+  PATH="$test_root/bin:$PATH"
+  BUZZ_DEV_LABEL='voice "route" \ fix'
+  BUZZ_SHARE_IDENTITY=0
+  source "$repo_root/scripts/instance-env.sh"
+  printf '%s\n%s\n%s\n' \
+    "$BUZZ_WORKTREE_LABEL" "$BUZZ_INSTANCE_SLUG" "$BUZZ_TAURI_CONFIG"
+)
+
+[[ "$result" == *$'voice "route" \ fix\nvoice-route-fix\n'* ]]
+config=$(printf '%s\n' "$result" | tail -1)
+[[ "$(node -e 'const c=JSON.parse(process.argv[1]); process.stdout.write(c.productName)' "$config")" == 'Buzz Dev (voice "route" \ fix)' ]]
+
+echo "instance-env tests passed"