fix(install): #54 safety guards + recovery hint

Offline compose-lock failure now fail-closes (reusing the cache.nixos.org
probe) instead of falling back to a network `nix flake lock`; a disk-review
warn fires when the target already carries Windows/BitLocker/NTFS/LUKS
(before the wipe); account password requires ≥8 chars like LUKS; on HM
pre-activate failure the installer drops a NOMARCHY-DESKTOP-NOT-THEMED.txt
recovery hint in the target home so first login still shows the fix.

Worktree agent; diff reviewed + cherry-picked. V0 flake check + V1
nomarchy-install build. Password ≥8 is V0-complete; the offline/NTFS/
pre-activate scenarios are V2-pending (crafted install runs).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

agent/BACKLOG.md

@@ -129,20 +129,15 @@ catppuccin) — btop.theme isn't contrast-checked.
   or **quarantine** (remove `waybar.css` → falls back to the generated bar),
   then capture the preview. V2 render.
 
-### 54. Installer safety + polish (promoted 2026-07-09, V0+V2)
+### 54. Installer safety + polish — V2 scenarios pending
-- **Offline fail-closed:** when the offline path is active and
+Four guards shipped 2026-07-09 (V0/V1: bash -n, flake check, nomarchy-install
-  `compose-lock.py` fails, the script currently *warns* and runs `nix flake
+builds): offline `compose-lock` failure now fail-closes instead of a network
-  lock` (needs network) → a promised offline install can hang. Fail the
+`flake lock`; disk-review `warn` when the target shows Windows/BitLocker/NTFS/
-  install with a clear message instead. (V2 offline install.)
+LUKS; account password min 8 (mirrors LUKS); HM pre-activate failure drops a
-- **Destructive-data warning:** at disk selection/review, if `lsblk -f`/`blkid`
+`NOMARCHY-DESKTOP-NOT-THEMED.txt` hint on the target home. **Remaining V2**
-  shows Windows/BitLocker/NTFS/existing-LUKS on the **chosen** disk, add one
+(need crafted install scenarios): offline install actually failing closed; an
-  explicit "data will be destroyed" line. Single whole-disk only — no
+NTFS/BitLocker disk firing the warning; the pre-activate hint landing on a
-  dual-boot path. (V0 + V2.)
+booted target. (Password ≥8 is V0-complete.)
-- **Password min length = 8:** the account password only requires non-empty
-  while LUKS needs ≥8 — align to one 8-char rule (not a strength meter). (V0.)
-- **HM pre-activate recovery hint:** on pre-activate failure, drop a flag
-  file / MOTD snippet on the target so first login still shows the fix
-  (observed warning this session; the install still booted themed). (V2.)
 
 ## LATER
 

agent/JOURNAL.md

@@ -17,6 +17,18 @@ Template:
 
 ---
 
+## 2026-07-09 — #54 installer safety + polish (delegated, worktree)
+- **Task:** NEXT #54. Sonnet worktree agent (installer only).
+- **Did:** offline `compose-lock` failure fail-closes (reuses the
+  cache.nixos.org probe → `OFFLINE`) instead of a network `flake lock`;
+  disk-review `warn` on Windows/BitLocker/NTFS/LUKS signatures (before wipe);
+  account password min 8 (mirrors LUKS); HM pre-activate failure drops a
+  recovery-hint file on the target home. Diff reviewed + cherry-picked.
+- **Verified:** V0 flake check + V1 `nix build .#nomarchy-install`. V2 (offline
+  fail path, NTFS-disk warning, pre-activate hint on a booted target) needs
+  crafted scenarios — queued in slimmed #54. Password ≥8 is V0-complete.
+- **Next:** cheap scripted btop check for #52; then session wrap.
+
 ## 2026-07-09 — #52 theme fidelity Broken/high-ROI fixes (delegated, worktree)
 - **Task:** NEXT #52. Sonnet worktree agent (parallel, theme files only).
 - **Did:** Six defects fixed: rose-pine btop→Dawn, everforest/summer-night

pkgs/nomarchy-install/nomarchy-install.sh

@@ -89,7 +89,9 @@ export NIX_CONFIG="flake-registry = $SHARE/registry.json"
 # substituter resolves to the TARGET store (i.e. itself), so without
 # this nothing flows from the ISO and nix bootstraps gcc from source.
 NIXOS_INSTALL_OPTS=()
+OFFLINE=false
 if ! timeout 3 bash -c '</dev/tcp/cache.nixos.org/443' 2>/dev/null; then
+    OFFLINE=true
     info "No network — substituting from the ISO store only."
     NIX_CONFIG+=$'\nsubstituters =\nextra-substituters = daemon?trusted=1\nbuilders ='
     # Must ALSO go through nixos-install as a flag: it passes its own
@@ -122,6 +124,15 @@ fi
 [[ -b "$TARGET_DISK" ]] || fail "$TARGET_DISK is not a block device."
 info "Target: $TARGET_DISK"
 
+# Single whole-disk install only (no dual-boot path) — if the chosen disk
+# already carries a recognizable OS/filesystem signature, call it out
+# explicitly before the pre-wipe below destroys it.
+existing_sig="$(lsblk -no FSTYPE,LABEL "$TARGET_DISK" 2>/dev/null || true
+                blkid "$TARGET_DISK"* 2>/dev/null || true)"
+if grep -qiE 'ntfs|bitlocker|microsoft|crypto_luks' <<< "$existing_sig"; then
+    warn "$TARGET_DISK has existing data (Windows/BitLocker/NTFS or LUKS) — it will be destroyed."
+fi
+
 # ─── Encryption ─────────────────────────────────────────────────────────
 section "Disk encryption"
 
@@ -181,8 +192,8 @@ else
         warn "Invalid username (lowercase letters, digits, - and _)."
     done
     while true; do
-        PASSWORD=$(gum input --password --placeholder "password for $USERNAME")
+        PASSWORD=$(gum input --password --placeholder "password for $USERNAME (min 8 chars)")
-        [[ -n "$PASSWORD" ]] || { warn "Empty password."; continue; }
+        [[ ${#PASSWORD} -ge 8 ]] || { warn "Too short (min 8 chars)."; continue; }
         p2=$(gum input --password --placeholder "repeat password")
         [[ "$PASSWORD" == "$p2" ]] && break
         warn "Passwords don't match."
@@ -445,6 +456,9 @@ PYJSON
 # `nix flake update` on the installed machine re-resolves normally).
 if ! python3 "$SHARE/compose-lock.py" "$SHARE/flake.lock" "$FLAKE_DIR/flake.lock" \
         "$NOMARCHY_LOCKED_JSON" "$NOMARCHY_ORIGINAL_JSON"; then
+    if [[ "$OFFLINE" == true ]]; then
+        fail "Offline lock composition failed and there is no network to fall back to — cannot finish an offline install."
+    fi
     warn "Offline lock composition failed — resolving over the network."
     (cd "$FLAKE_DIR" && nix --extra-experimental-features "nix-command flakes" flake lock)
 fi
@@ -577,6 +591,20 @@ else
     warn "on the installed system); after first login run:"
     warn "  home-manager switch --flake ~/.nomarchy -b bak"
     tail -n 5 /mnt/var/log/nomarchy-hm-preactivate.log 2>/dev/null || true
+    # The live session (and this warning) ends with this install — drop a
+    # durable hint on the TARGET so the fix still surfaces on first login.
+    # Numeric ids: the account doesn't exist in the live environment yet
+    # (same reasoning as the $FLAKE_DIR chown above).
+    hint_file="/mnt/home/$USERNAME/NOMARCHY-DESKTOP-NOT-THEMED.txt"
+    cat > "$hint_file" <<HINT
+Desktop pre-activation failed during install — see
+/var/log/nomarchy-hm-preactivate.log for details. Finish it with:
+
+    home-manager switch --flake ~/.nomarchy -b bak
+
+(delete this file once done)
+HINT
+    chown 1000:100 "$hint_file"
 fi
 rm -f /mnt/root/nomarchy-hm-activate.sh