0.6.8: Pin sldl skip index + fix dedup scan blinded by the path rewrite

Two bugs conspired to fill the library with .1.flac duplicates on the
night of 2026-07-15/16:

1. sldl derives its skip-index folder from the input: the Spotify
   playlist display name before 0.6.2, the CSV filename after. The
   switch stranded every playlist's download history in the old
   emoji-named subfolder, so sldl started from an empty index and
   re-downloaded every playlist in full. Fix: pin index-path in
   _template.conf, seed the pinned file from all stranded indexes
   (merge-sldl-indexes.py, called from run-playlist.sh whenever the
   pinned index is missing or older than a stranded one). Recovered
   rows keep the CSV-era identity fields but are marked downloaded, so
   tracks that failed last night yet exist in the library since months
   ago are not fetched again.

2. The safety net that should have flagged the flood, dedup-library.sh,
   has silently reported 0 groups since the 2026-07-08 path rewrite:
   host_path() still assumed /music/... display paths and prepended the
   library dir to already-correct /data/music/Library/... paths, so
   every candidate failed the -f check. Fix: pass real paths through
   unchanged, keep the /music prefix swap only for legacy entries.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

pipeline/lib/dedup-library.sh

@@ -78,8 +78,22 @@ fi
 # Counters: tracked via log grep at the end (avoids bash subshell pitfalls).
 # Functions write KEEP/DELETE lines with consistent prefixes; summary greps them.
 
-# Convert container path (/music/...) to host path (${MUSIC_DATA_DIR:-/data/music}/Library/...)
-host_path() { echo "${MUSIC_DATA_DIR:-/data/music}/Library${1#/music}"; }
+# Resolve a beets-displayed path to a real path in this container. Since the
+# 2026-07-08 path rewrite, beets displays ${MUSIC_DATA_DIR:-/data/music}/Library/...
+# paths that are directly usable — pass those through UNCHANGED. Only legacy
+# /music/... display paths (the pre-rewrite transitional mount) still need the
+# prefix swap. Blindly prepending the library dir to an already-correct path
+# (the old behavior) produced /data/music/Library/data/music/Library/... —
+# nonexistent, so every candidate failed the -f check and every pass reported
+# 0 groups from 2026-07-08 until this fix.
+host_path() {
+  local p="$1"
+  if [[ "$p" == /music/* ]]; then
+    echo "${MUSIC_DATA_DIR:-/data/music}/Library${p#/music}"
+  else
+    echo "$p"
+  fi
+}
 
 SEP=$'\x1c'  # ASCII file separator — safe with any music metadata
 
@@ -202,9 +216,10 @@ process_group() {
 log ""
 log "[$(date -Iseconds)] === Pass 1: numbered siblings ==="
 
-# Dump id + container path from beets once. beets normalizes $path for
-# display (always /music/-prefixed) even though the DB stores a mix of
-# absolute and relative — so the display paths are safe to compare/convert,
+# Dump id + display path from beets once. beets normalizes $path for display
+# (real /data/music/Library/... paths since the 2026-07-08 rewrite; /music/...
+# on any legacy entry) even though the DB stores a mix of absolute and
+# relative — so the display paths are safe to compare/convert via host_path(),
 # and the ids are what we hand to beet remove/move.
 beet ls -f "\$id${SEP}\$path" 2>/dev/null > /tmp/beets-id-paths.txt
 cut -d"$SEP" -f2- /tmp/beets-id-paths.txt > /tmp/beets-all-paths.txt
@@ -231,7 +246,7 @@ while IFS="$SEP" read -r numbered_id numbered_cp; do
 
   if [[ $score_canonical -le $score_numbered ]]; then
     # Canonical wins: delete numbered (in beets), keep canonical (ghost)
-    process_group "P1 numbered-sibling: ${numbered_cp##/music/}" \
+    process_group "P1 numbered-sibling: ${numbered_cp##*/Library/}" \
       "$host_canonical" "${numbered_id}${SEP}${numbered_cp}"
     if [[ $APPLY -eq 1 ]]; then
       # canonical is now a ghost file; import it into beets
@@ -240,7 +255,7 @@ while IFS="$SEP" read -r numbered_id numbered_cp; do
   else
     # Numbered wins (canonical is ghost): rm the ghost, then beet move to rename
     # the numbered file to the canonical path (id query — see process_group).
-    process_group "P1 numbered-sibling: ${numbered_cp##/music/}" \
+    process_group "P1 numbered-sibling: ${numbered_cp##*/Library/}" \
       "${numbered_id}${SEP}${numbered_cp}" "$host_canonical"
     if [[ $APPLY -eq 1 ]]; then
       beet move "id:${numbered_id}" >> "$LOG" 2>&1 || log "  WARN: beet move id:${numbered_id} failed"