diff --git a/lib/higgsfield-skills.sh b/lib/higgsfield-skills.sh
new file mode 100644
index 0000000..51de21c
--- /dev/null
+++ b/lib/higgsfield-skills.sh
@@ -0,0 +1,79 @@
+#!/usr/bin/env bash
+# ============================================================
+# lib/higgsfield-skills.sh — Higgsfield skill pack sync + CLI probes
+#
+# Sourced by install-plugins.sh (Step 8.6), update-all.sh (7.3b) and
+# doctor.sh. The pack is machine-owned: cloned from upstream and moved
+# into skills-external/higgsfield-* (gitignored), then linked on demand by
+# lib/toggle-external.sh. It is listed in neither link.sh nor any profile:
+# either would re-enable a parked pack on every run (BDR-093).
+# ============================================================
+
+# Upstream skills repo, single source for both installers. An env value
+# wins so the hermetic suite can point it at a local fixture repo.
+HIGGSFIELD_SKILLS_URL="${HIGGSFIELD_SKILLS_URL:-\
+https://github.com/higgsfield-ai/skills.git}"
+
+# _higgsfield_adopt <clone> <dest>
+# Move every real higgsfield-*/ directory of the clone that holds a SKILL.md
+# over its copy in <dest>; prints how many landed. A symlinked entry is
+# skipped: only upstream's own directories are adopted. A skill counts only
+# once its move succeeded.
+_higgsfield_adopt() {
+  local clone="$1" dest="$2" dir name count=0
+  for dir in "$clone"/higgsfield-*/; do
+    dir="${dir%/}"
+    { [ -f "$dir/SKILL.md" ] && [ ! -L "$dir" ]; } || continue
+    name="$(basename "$dir")"
+    rm -rf "${dest:?}/${name:?}" && mv "$dir" "$dest/$name" \
+      && count=$((count + 1))
+  done
+  echo "$count"
+}
+
+# higgsfield_sync_skills <repo>
+# Clone upstream into a stage and replace each
+# <repo>/skills-external/higgsfield-* with the fresh copy; upstream's own
+# machinery (setup, scripts/, plugin manifests, .git) stays in the stage.
+# The stage sits next to the destination, on the same filesystem, so each
+# replacement is a rename. Prints the number of skills synced. Returns 1,
+# existing copies untouched, when the clone fails or upstream holds no
+# higgsfield-*/SKILL.md. A parked skill (skills-disabled/<name>, a symlink
+# to the source path) stays parked. Known limit: a skill that upstream
+# removes or renames keeps its last local copy.
+higgsfield_sync_skills() {
+  local dest="$1/skills-external" stage count=0
+  mkdir -p "$dest" || return 1
+  stage="$(mktemp -d "$dest/.higgsfield-stage.XXXXXX")" || return 1
+  # No credential prompt of any kind: a private or deleted upstream must
+  # fail at once, not wait on a terminal, an askpass program (an editor's
+  # terminal exports one) or a credential helper.
+  if GIT_TERMINAL_PROMPT=0 GIT_ASKPASS='' SSH_ASKPASS='' \
+      git -c credential.helper= -c core.askPass= clone --quiet --depth 1 \
+      "$HIGGSFIELD_SKILLS_URL" "$stage/src" </dev/null >/dev/null 2>&1; then
+    count="$(_higgsfield_adopt "$stage/src" "$dest")"
+  fi
+  rm -rf "${stage:?}"
+  echo "$count"
+  [ "$count" -gt 0 ]
+}
+
+# _higgsfield_probe <args...>
+# Run `higgsfield <args>` silently, 15 s at most when `timeout` exists. The
+# CLI is closed source: a probe must never hang an installer, and what it
+# prints (a token, for `auth token`) must never reach a terminal or a log.
+_higgsfield_probe() {
+  if command -v timeout >/dev/null 2>&1; then
+    timeout 15 higgsfield "$@" </dev/null >/dev/null 2>&1
+  else
+    higgsfield "$@" </dev/null >/dev/null 2>&1
+  fi
+}
+
+# higgsfield_cli_ok — 0 when the binary answers. `command -v` alone only
+# proves the npm shim: the binary is vendored by a postinstall script that
+# npm may hold back, on a first install or on any later update.
+higgsfield_cli_ok() { _higgsfield_probe version; }
+
+# higgsfield_signed_in — 0 when the CLI holds a session.
+higgsfield_signed_in() { _higgsfield_probe auth token; }
diff --git a/lib/tests/higgsfield.test.sh b/lib/tests/higgsfield.test.sh
new file mode 100644
index 0000000..813e660
--- /dev/null
+++ b/lib/tests/higgsfield.test.sh
@@ -0,0 +1,168 @@
+#!/usr/bin/env bash
+# lib/tests/higgsfield.test.sh — hermetic suite for the Higgsfield pack.
+#   sync    lib/higgsfield-skills.sh against a local git repo shaped like
+#           upstream (no network), and its CLI probes against a fake CLI
+#   toggle  lib/toggle-external.sh `higgsfield` / `higgsfield-websites`
+#           against a fixture tree, fake CLIs first on PATH
+#   wiring  static locks on the installers (order, off by default)
+# Each named case prints one `PASS <NAME>` or `FAIL <NAME>:<details>` line.
+set -u
+ROOT="$(cd "$(dirname "$0")/../.." && pwd)"
+pass=0; fail=0; errs=""
+
+# expect <label> <got> <want> — record a mismatch for the current case.
+expect() { [ "$2" = "$3" ] || errs="$errs $1(got[$2] want[$3])"; }
+# expect_has / expect_not <label> <text> <fragment>
+expect_has() { case "$2" in *"$3"*) ;; *) errs="$errs $1(lacks[$3])" ;; esac; }
+expect_not() { case "$2" in *"$3"*) errs="$errs $1(has[$3])" ;; esac; }
+# verdict <NAME> — close the current case: PASS when nothing was recorded.
+verdict() {
+  if [ -z "$errs" ]; then pass=$((pass + 1)); printf 'PASS %s\n' "$1"
+  else fail=$((fail + 1)); printf 'FAIL %s:%s\n' "$1" "$errs"; fi
+  errs=""
+}
+# yn <command...> — "yes" when the command succeeds, else "no".
+yn() { if "$@" 2>/dev/null; then echo yes; else echo no; fi; }
+# entries <dir> — how many entries the directory holds, hidden ones included.
+entries() { find "$1" -mindepth 1 -maxdepth 1 | wc -l | tr -d ' '; }
+
+WORK="$(mktemp -d)"
+trap 'rm -rf "$WORK"' EXIT
+
+# Fake CLIs, first on PATH in every case that needs one. `higgsfield`
+# answers per $FAKE_HF_BINARY (ok | missing: the npm shim without its
+# binary) and $FAKE_HF_SESSION (in | out).
+BIN="$WORK/bin"; mkdir -p "$BIN"
+cat > "$BIN/higgsfield" <<'EOF'
+#!/usr/bin/env bash
+if [ "${FAKE_HF_BINARY:-ok}" = missing ]; then
+  echo "@higgsfield/cli: binary not found" >&2; exit 1
+fi
+case "${1:-} ${2:-}" in
+  "version ") echo "higgsfield 0.0.0 (fixture) built never"; exit 0 ;;
+  "auth token")
+    if [ "${FAKE_HF_SESSION:-in}" = in ]; then echo "fixture-token"; exit 0; fi
+    echo "Error: Not authenticated." >&2; exit 2 ;;
+esac
+exit 64
+EOF
+cat > "$BIN/21st" <<'EOF'
+#!/usr/bin/env bash
+[ "${1:-}" = whoami ] && echo "Logged in as fixture (saved in fixture)."
+EOF
+chmod +x "$BIN/higgsfield" "$BIN/21st"
+
+# A PATH that holds the tools the scripts under test need and nothing else:
+# no `higgsfield`, no `timeout`, whatever this machine has installed.
+CLEAN="$WORK/cleanbin"; mkdir -p "$CLEAN"
+for t in bash dirname basename mkdir mv rm ln sed; do
+  ln -s "$(command -v "$t")" "$CLEAN/$t"
+done
+
+# git_q <dir> <git args...> — quiet git in a fixture repo: own identity, no
+# hooks, so the machine's global git config never leaks in.
+git_q() {
+  local dir="$1"; shift
+  git -C "$dir" -c user.name=fixture -c user.email=fixture@example.invalid \
+    -c core.hooksPath=/dev/null -c init.defaultBranch=trunk "$@" \
+    >/dev/null 2>&1
+}
+
+# mk_upstream <dir> — a git repo shaped like the upstream skills repo: three
+# pack skills, a pack-named dir with no SKILL.md, a pack-named symlink to
+# a foreign skill, and root machinery that must never be synced.
+mk_upstream() {
+  local up="$1" s
+  mkdir -p "$up/scripts" "$up/higgsfield-noskill" "$up/other-skill"
+  for s in higgsfield-generate higgsfield-soul-id higgsfield-websites; do
+    mkdir -p "$up/$s/references"
+    printf -- '---\nname: %s\n---\n' "$s" > "$up/$s/SKILL.md"
+    echo "ref" > "$up/$s/references/notes.md"
+  done
+  echo "old" > "$up/higgsfield-generate/old.md"
+  echo "no skill here" > "$up/higgsfield-noskill/README.md"
+  ln -s other-skill "$up/higgsfield-linked"
+  echo "---" > "$up/other-skill/SKILL.md"
+  echo "#!/bin/sh" > "$up/setup"
+  echo "#!/bin/sh" > "$up/scripts/update-check.sh"
+  git_q "$up" init
+  git_q "$up" add -A
+  git_q "$up" commit -m fixture
+}
+
+# sync_into <repo> [url] — run the helper in a subshell; prints "<rc>:<count>".
+sync_into() {
+  (
+    export HIGGSFIELD_SKILLS_URL="${2:-$UP}"
+    # shellcheck source=lib/higgsfield-skills.sh disable=SC1091
+    source "$ROOT/lib/higgsfield-skills.sh"
+    out="$(higgsfield_sync_skills "$1")"
+    printf '%s:%s' "$?" "$out"
+  )
+}
+
+# probe <path> <function> — run one CLI probe of the helper on the given
+# PATH; prints everything it wrote, then "rc=<status>".
+probe() {
+  PATH="$1" bash -c 'source "$1/lib/higgsfield-skills.sh"; "$2"; echo "rc=$?"' \
+    _ "$ROOT" "$2" 2>&1
+}
+
+# ── sync ────────────────────────────────────────────────────
+UP="$WORK/upstream"; mk_upstream "$UP"
+R1="$WORK/r1"; mkdir -p "$R1/skills" "$R1/skills-disabled"
+EXT="$R1/skills-external"
+
+expect fixture  "$(yn test -f "$UP/.git/HEAD")" yes
+expect rc-count "$(sync_into "$R1")" "0:3"
+expect generate "$(yn test -f "$EXT/higgsfield-generate/SKILL.md")" yes
+expect refs \
+  "$(yn test -f "$EXT/higgsfield-soul-id/references/notes.md")" yes
+expect websites "$(yn test -f "$EXT/higgsfield-websites/SKILL.md")" yes
+expect noskill  "$(yn test -e "$EXT/higgsfield-noskill")" no
+expect symlink  "$(yn test -L "$EXT/higgsfield-linked")" no
+expect no-other "$(yn test -e "$EXT/other-skill")" no
+expect no-setup "$(yn test -e "$EXT/setup")" no
+expect no-git   "$(find "$EXT" -name .git | wc -l | tr -d ' ')" 0
+expect entries  "$(entries "$EXT")" 3
+verdict SYNC_MOVES_PACK_ONLY
+
+rm "$UP/higgsfield-generate/old.md"
+echo "new" > "$UP/higgsfield-generate/new.md"
+git_q "$UP" add -A; git_q "$UP" commit -m refresh
+expect before    "$(yn test -f "$EXT/higgsfield-generate/old.md")" yes
+expect rc-count  "$(sync_into "$R1")" "0:3"
+expect stale-out "$(yn test -e "$EXT/higgsfield-generate/old.md")" no
+expect new-in    "$(yn test -f "$EXT/higgsfield-generate/new.md")" yes
+verdict SYNC_REFRESH_DROPS_STALE
+
+ln -s "$EXT/higgsfield-soul-id" "$R1/skills-disabled/higgsfield-soul-id"
+ln -s "$EXT/higgsfield-generate" "$R1/skills/higgsfield-generate"
+expect rc-count    "$(sync_into "$R1")" "0:3"
+expect parked-link "$(yn test -L "$R1/skills-disabled/higgsfield-soul-id")" yes
+expect parked-reads \
+  "$(yn test -f "$R1/skills-disabled/higgsfield-soul-id/SKILL.md")" yes
+expect not-enabled "$(yn test -e "$R1/skills/higgsfield-soul-id")" no
+expect live-reads  "$(yn test -f "$R1/skills/higgsfield-generate/SKILL.md")" yes
+verdict SYNC_KEEPS_PARKED
+
+BARE="$WORK/bare-upstream"; mkdir -p "$BARE"; echo "x" > "$BARE/README.md"
+git_q "$BARE" init; git_q "$BARE" add -A; git_q "$BARE" commit -m fixture
+expect no-repo   "$(sync_into "$R1" "$WORK/no-such-repo")" "1:0"
+expect no-skills "$(sync_into "$R1" "$BARE")" "1:0"
+expect copy-kept "$(yn test -f "$EXT/higgsfield-generate/new.md")" yes
+expect entries   "$(entries "$EXT")" 3
+verdict SYNC_FAIL_KEEPS_COPY
+
+expect cli-ok      "$(probe "$BIN:$PATH" higgsfield_cli_ok)" "rc=0"
+expect signed-in   "$(probe "$BIN:$PATH" higgsfield_signed_in)" "rc=0"
+expect signed-out  \
+  "$(FAKE_HF_SESSION=out probe "$BIN:$PATH" higgsfield_signed_in)" "rc=2"
+expect shim-only   \
+  "$(FAKE_HF_BINARY=missing probe "$BIN:$PATH" higgsfield_cli_ok)" "rc=1"
+expect no-cli      "$(probe "$CLEAN" higgsfield_cli_ok)" "rc=127"
+expect no-timeout  "$(probe "$BIN:$CLEAN" higgsfield_cli_ok)" "rc=0"
+verdict PROBES_SILENT
+
+# ── tally ───────────────────────────────────────────────────
+printf 'PASS=%s FAIL=%s\n' "$pass" "$fail"; [ "$fail" -eq 0 ]