install.sh: merge PERSONAL_DIRS contents instead of wholesale replace

The previous deploy_one() did `mv $HOME/<dir> $BACKUP_DIR/<dir>` then
`cp -a $YADR_DIR/<dir> $HOME/<dir>` for every entry in PERSONAL_DIRS.
For dirs the repo only partially populates (notably .local — repo only
tracks .local/bin/), this swept away unrelated user data: the most
recent re-bootstrap moved ~/.local/share/fonts/ (Intel One Mono, Open
Gorton, Roboto Mono, GALLAUDET, code128) into the timestamped backup,
making them appear missing.

Rework deploy logic:
- deploy_file: copies one file/symlink, backing up only the conflicting
  destination (if any). Idempotent via paths_equivalent() so re-runs
  with no changes produce no output and no spurious backups.
- deploy_dir: walks the repo's tree for that dir and deploys each leaf
  via deploy_file. Files in $HOME the repo doesn't know about are left
  untouched. Subdirs are mkdir'd as needed.

Also: track the personal fonts at .local/share/fonts/ so they redeploy
on every install, and run fc-cache -f at the end so apps see them
without a logout/login.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

install.sh

@@ -30,7 +30,11 @@ PERSONAL_FILES=(
   .zprofile .zshenv .zshrc
 )
 
-# Directories deployed wholesale to $HOME/<dir>/.
+# Directories whose contents are merged into $HOME/<dir>/, file by file. Files
+# the repo provides replace conflicting on-disk versions (with the displaced
+# version preserved in $BACKUP_DIR); files outside the repo's tree are left
+# untouched. This deliberately avoids wholesale-replacing $HOME/.local etc.,
+# which would sweep away unrelated user data (fonts, app state, ...).
 PERSONAL_DIRS=(
   .fonts .irssi .nano .themes .local .mplayer
 )
@@ -83,31 +87,80 @@ else
 fi
 
 # 3. Deploy personal dotfiles
-backup_one() {
-  local src_name="$1"
-  local dst="$HOME/$src_name"
+
+# Move $HOME/<rel> aside into $BACKUP_DIR, preserving its sub-path.
+backup_one_path() {
+  local rel="$1"
+  local dst="$HOME/$rel"
   if [ -e "$dst" ] || [ -L "$dst" ]; then
-    mkdir -p "$BACKUP_DIR/$(dirname "$src_name")"
-    mv "$dst" "$BACKUP_DIR/$src_name"
+    mkdir -p "$BACKUP_DIR/$(dirname "$rel")"
+    mv "$dst" "$BACKUP_DIR/$rel"
   fi
 }
 
-deploy_one() {
-  local name="$1"
-  local src="$YADR_DIR/$name"
-  local dst="$HOME/$name"
+# Returns 0 iff $1 and $2 are equivalent (same symlink target, or identical
+# regular-file content). Used to make re-runs idempotent: unchanged files get
+# skipped instead of needlessly backed up.
+paths_equivalent() {
+  local a="$1" b="$2"
+  if [ -L "$a" ] && [ -L "$b" ]; then
+    [ "$(readlink "$a")" = "$(readlink "$b")" ]
+  elif [ -L "$a" ] || [ -L "$b" ]; then
+    return 1
+  elif [ -f "$a" ] && [ -f "$b" ]; then
+    cmp -s "$a" "$b"
+  else
+    return 1
+  fi
+}
+
+# Deploy one file or symlink at $YADR_DIR/<rel> to $HOME/<rel>. If a different
+# file/symlink is already at the destination, it's moved into $BACKUP_DIR first.
+deploy_file() {
+  local rel="$1"
+  local src="$YADR_DIR/$rel"
+  local dst="$HOME/$rel"
   if [ ! -e "$src" ] && [ ! -L "$src" ]; then
     return
   fi
-  backup_one "$name"
+  if paths_equivalent "$src" "$dst"; then
+    return
+  fi
+  backup_one_path "$rel"
   mkdir -p "$(dirname "$dst")"
   cp -a "$src" "$dst"
-  info "$name"
+  info "$rel"
+}
+
+# Deploy a directory by walking its tree and deploying each file/symlink in
+# turn. Directories get mkdir'd; existing entries inside $HOME/<rel> that the
+# repo doesn't know about are left alone. This is the merge semantics that
+# protects e.g. $HOME/.local/share/fonts from being clobbered when the repo
+# only tracks $HOME/.local/bin.
+deploy_dir() {
+  local rel="$1"
+  local src="$YADR_DIR/$rel"
+  if [ ! -d "$src" ] || [ -L "$src" ]; then
+    return
+  fi
+  mkdir -p "$HOME/$rel"
+  local sub sub_rel src_path
+  while IFS= read -r -d '' sub; do
+    sub="${sub#./}"
+    [ "$sub" = "." ] && continue
+    sub_rel="$rel/$sub"
+    src_path="$YADR_DIR/$sub_rel"
+    if [ -d "$src_path" ] && [ ! -L "$src_path" ]; then
+      mkdir -p "$HOME/$sub_rel"
+      continue
+    fi
+    deploy_file "$sub_rel"
+  done < <(cd "$src" && find . -mindepth 1 -print0)
 }
 
 log "Deploying personal dotfiles"
-for f in "${PERSONAL_FILES[@]}"; do deploy_one "$f"; done
-for d in "${PERSONAL_DIRS[@]}"; do deploy_one "$d"; done
+for f in "${PERSONAL_FILES[@]}"; do deploy_file "$f"; done
+for d in "${PERSONAL_DIRS[@]}"; do deploy_dir "$d"; done
 
 # .local/bin/claude is a relative symlink to ../share/claude/versions/...
 # If that target isn't present on this machine, remove the dangling link so
@@ -137,6 +190,13 @@ if [ -d "$HOME/.local/bin" ]; then
   find "$HOME/.local/bin" -maxdepth 1 -type f -exec chmod +x {} \; 2>/dev/null || true
 fi
 
+# 5. Refresh font cache so newly-deployed .fonts/ and .local/share/fonts/
+# entries are visible to apps without a logout/login.
+if have fc-cache; then
+  log "Refreshing font cache"
+  fc-cache -f >/dev/null 2>&1 || warn "fc-cache returned non-zero; continuing"
+fi
+
 echo
 log "Done."
 if [ -d "$BACKUP_DIR" ]; then