Fail when failing, stop when stopped, and survive what is neither

Four installer bugs, all in the space between exit codes and intent:

- A flatpak-only extras category -- most of them -- died at the grep
  that filters out its dnf half, because grep exits 1 on zero matches
  and set -e read that as failure. sed deletes lines without editorial
  comment. The extras contract now runs a flatpak-only category under
  the installer's own strict options so this stays fixed.
- A rate-limited GitHub API call aborted the whole package stage while
  resolving the RustDesk URL, even though the empty-result fallback was
  sitting right below it. The pipeline is now guarded so the fallback
  is reachable.
- Ctrl-C did not stop the install: the INT trap ran cleanup and bash
  carried on with the remaining stages, MOK enrollment and firmware
  included. INT and TERM now exit explicitly; cleanup rides EXIT.
- change-settings and link-dotfiles ran without set -e, so a failed
  copy over / or a failed symlink fell through to guarded no-ops and
  the stage reported success. Turning strictness on immediately caught
  what it had been hiding: link-dotfiles never created ~/.config, so on
  a truly fresh HOME every symlink was failing silently.

install

@@ -38,7 +38,13 @@ cleanup() {
   # design, and one of them is an email address.
   [[ -n "${PANAMA_ANSWERS:-}" ]] && rm -f "$PANAMA_ANSWERS"
 }
-trap cleanup EXIT INT TERM
+trap cleanup EXIT
+# A bare `trap cleanup INT` is not an abort: bash runs the handler and then
+# carries on with the script, so Ctrl-C would kill only the current stage and
+# the remaining ones -- MOK enrollment, firmware -- would still run. Exit
+# explicitly instead; the EXIT trap above does the actual cleanup.
+trap 'exit 130' INT
+trap 'exit 143' TERM
 
 gsettings set org.gnome.desktop.screensaver lock-enabled false 2>/dev/null || true
 gsettings set org.gnome.desktop.session idle-delay 0 2>/dev/null || true

setup/scripts/install-packages

@@ -214,9 +214,12 @@ if rpm -q rustdesk >/dev/null 2>&1; then
   log "RustDesk already installed"
 else
   log "Resolving the latest RustDesk release..."
+  # `|| true` because a failed curl -- unauthenticated GitHub API calls get
+  # rate-limited -- would otherwise trip set -e and kill the stage before the
+  # empty-result fallback below could do its job.
   rustdesk_url="$(curl -fsSL https://api.github.com/repos/rustdesk/rustdesk/releases/latest 2>/dev/null \
     | jq -r '.assets[].browser_download_url | select(test("x86_64\\.rpm$")) | select(test("suse") | not)' \
-    | head -1)"
+    | head -1 || true)"
   if [[ -n "$rustdesk_url" ]]; then
     log "Installing RustDesk from $rustdesk_url"
     # The RPM ships rustdesk.service already enabled, which is what provides
@@ -271,7 +274,9 @@ install_extra_category() {
 	name="$(basename "$file")"
 
 	local dnf_packages flatpak_ids
-	dnf_packages=$(catalog_all_targets "$file" | grep -v '^flatpak:' | tr "\n" " ")
+	# sed rather than grep -v: most categories are flatpak-only, and grep exits 1
+	# when it selects nothing, which set -e above turns into a dead stage.
+	dnf_packages=$(catalog_all_targets "$file" | sed '/^flatpak:/d' | tr "\n" " ")
 	flatpak_ids=$(catalog_all_targets "$file" | sed -n 's/^flatpak://p' | tr "\n" " ")
 
 	if [[ -n "${dnf_packages// /}" ]]; then

setup/scripts/link-dotfiles

@@ -1,5 +1,10 @@
 #!/usr/bin/env bash
 
+# Strict: a failed mv or ln here used to fall through and exit 0, so a machine
+# could end up half-linked while the installer's summary reported the stage as
+# fine. Anything genuinely optional below carries its own `|| true`.
+set -euo pipefail
+
 # --- Helper functions ---
 log() { echo -e "\033[1;34m[INFO]\033[0m $*"; }
 
@@ -10,8 +15,10 @@ PANAMA_DOT="$PANAMA_PATH/config/dot"
 PANAMA_OLD="$PANAMA_PATH/config/old"
 CONFIG="$HOME/.config"
 
-# Make backup folder if it doesn't exist
-mkdir -p "$PANAMA_OLD"
+# Make backup folder if it doesn't exist -- and ~/.config itself, which a
+# truly fresh HOME does not have yet. Before set -e above, its absence made
+# every symlink below fail silently while the stage still reported success.
+mkdir -p "$PANAMA_OLD" "$CONFIG"
 
 # --- Bashrc ---
 echo -e "\n--- Replacing .bashrc ---"

tests/setup/extras-contract

@@ -115,6 +115,31 @@ if grep 'flatpak install' <<<"$recorded" | grep -q 'from-dnf'; then
     note 'a dnf package is passed to flatpak'
 fi
 
+# A flatpak-only category -- which most of the real ones are -- must survive
+# the installer's own strict options. Filtering the dnf half with `grep -v`
+# once left an exit 1 for zero matches, and set -e killed the stage before its
+# flatpak half ran. Run under those options, not the contract's laxer ones;
+# the status is captured rather than `||`-guarded because a condition context
+# would switch errexit off inside the subshell and hide the very failure this
+# pins.
+: >"$calls"
+flatpak_only="$work/flatpak-only"
+printf 'flatpak:org.example.OnlyFlatpak\n' >"$flatpak_only"
+(
+    set -euo pipefail
+    PATH="$stub_dir:$PATH"
+    log() { :; }
+    source "$catalog"
+    eval "$filter"
+    eval "$loop"
+    install_extra_category "$flatpak_only"
+)
+flatpak_only_status=$?
+(( flatpak_only_status == 0 )) \
+    || note 'a flatpak-only category aborts the installer under set -euo pipefail'
+grep -q 'flatpak install -y flathub org.example.OnlyFlatpak' <<<"$(cat "$calls" 2>/dev/null)" \
+    || note 'a flatpak-only category installs nothing'
+
 # Choosing nothing installs nothing.
 : >"$calls"
 (

tests/setup/interview-contract

@@ -52,8 +52,15 @@ done <<<"$consumed"
 
 # ── 3. Nothing is left behind ────────────────────────────────────────────────
 
-grep -q 'trap cleanup EXIT INT TERM' "$install_script" \
-    || note 'install does not arm a cleanup trap on EXIT INT TERM'
+# Cleanup rides the EXIT trap; INT and TERM must exit explicitly, because a
+# trap handler that merely cleans up lets bash carry on with the remaining
+# stages after a Ctrl-C -- MOK enrollment and firmware included.
+grep -q 'trap cleanup EXIT' "$install_script" \
+    || note 'install does not arm a cleanup trap on EXIT'
+grep -qE "trap 'exit [0-9]+' INT" "$install_script" \
+    || note 'install does not exit on SIGINT, so Ctrl-C would keep installing'
+grep -qE "trap 'exit [0-9]+' TERM" "$install_script" \
+    || note 'install does not exit on SIGTERM, so a kill would keep installing'
 grep -q 'rm -f "$PANAMA_ANSWERS"' "$install_script" \
     || note 'the cleanup trap does not delete the answers file'
 grep -qE 'mktemp' "$install_script" \