diff --git a/install-plugins.sh b/install-plugins.sh
index 1d14597..38c5e7f 100644
--- a/install-plugins.sh
+++ b/install-plugins.sh
@@ -582,6 +582,8 @@ else
 fi
 # ctx7 auth — detect, then offer login ONLY in an interactive TTY. A non-interactive
 # run (CI / headless / re-run) must never open a browser or block on OAuth.
+# The test reads stdin alone: stdout is the tee pipe set up at the top of
+# this script, never a terminal.
 if command -v ctx7 &>/dev/null; then
   # Deterministic offline oracle: ctx7's OAuth token lives here (XDG-aware).
   # Present => authenticated; absent => anonymous. No subprocess, no network, no browser.
@@ -590,7 +592,7 @@ if command -v ctx7 &>/dev/null; then
     ok "ctx7 authenticated (full rate limits)"
   else
     info "ctx7 works anonymously — docs + library already usable, no auth required."
-    if [ -t 0 ] && [ -t 1 ]; then
+    if [ -t 0 ]; then
       # Interactive terminal: offer to log in now (opens a browser).
       printf '%b' "${BLUE}→${NC} Authenticate ctx7 now for higher rate limits? [y/N] "
       read -r ctx7_ans || ctx7_ans=""
@@ -990,6 +992,76 @@ for _stray in "$REPO/.agents/skills" "$REPO/.claude/skills"; do
 done
 echo ""
 
+# ============================================================
+# STEP 8.6 — HIGGSFIELD CLI + SKILL PACK
+# ============================================================
+# `@higgsfield/cli` (bins `higgsfield`, `higgs`): image, video, audio and
+# brand media generation from the terminal, one browser login, metered
+# credits. Its skills come from github.com/higgsfield-ai/skills, cloned by
+# lib/higgsfield-skills.sh into skills-external/higgsfield-* (gitignored).
+#
+# Nothing is linked here. The pack is OFF by default and belongs to no
+# profile: `lib/toggle-external.sh enable higgsfield` turns the media skills
+# on, `enable higgsfield-websites` the landing-page aid. Keeping it out of
+# link.sh and of every profile is what stops a re-run from re-enabling it
+# (BDR-093). This step runs before Step 8.7 so the effort pins are still
+# re-applied after the last vendoring step (BDR-108).
+echo "── Step 8.6: Higgsfield CLI + skill pack ───────────────────"
+echo ""
+# shellcheck source=lib/higgsfield-skills.sh disable=SC1091
+source "$REPO/lib/higgsfield-skills.sh"
+HF_PKG="@higgsfield/cli"
+# The package vendors its binary in a postinstall script that npm may hold
+# back; this form lets that one script run.
+HF_REMEDY="npm install -g --allow-scripts=${HF_PKG} ${HF_PKG}"
+
+# higgsfield_cli_ok, not `command -v`: the npm shim can sit on PATH with no
+# binary behind it, and only a probe tells the two apart.
+if higgsfield_cli_ok; then
+  ok "Higgsfield CLI already installed"
+else
+  HF_VER=$(pinned_version "higgsfield")
+  [ "$HF_VER" = "latest" ] || HF_PKG="${HF_PKG}@${HF_VER}"
+  info "Installing ${HF_PKG} (version from plugins.lock.json: ${HF_VER})..."
+  npm install -g "$HF_PKG" || true
+  if higgsfield_cli_ok; then
+    ok "Higgsfield CLI installed"
+  else
+    err "Higgsfield CLI install failed — run manually: $HF_REMEDY"
+  fi
+fi
+
+if higgsfield_cli_ok; then
+  # Skill pack — cloned to a stage, then moved under skills-external/.
+  if HF_N=$(higgsfield_sync_skills "$REPO"); then
+    ok "Higgsfield skill pack synced to skills-external/ ($HF_N skills)"
+  else
+    warn "Higgsfield skill pack sync failed — existing copies kept (check: git clone $HIGGSFIELD_SKILLS_URL)"
+  fi
+
+  # Auth — offer the login only when stdin is a terminal: a non-interactive
+  # run (CI / headless) must never open a browser or block on OAuth.
+  if higgsfield_signed_in; then
+    ok "Higgsfield: signed in"
+  elif [ -t 0 ]; then
+    printf '%b' "${BLUE}→${NC} Sign in to Higgsfield now? (opens a browser) [y/N] "
+    read -r hf_ans || hf_ans=""
+    if [[ "$hf_ans" =~ ^[Yy]([Ee][Ss])?$ ]]; then
+      if higgsfield auth login; then
+        ok "Higgsfield authenticated"
+      else
+        warn "Higgsfield login did not finish — re-run 'higgsfield auth login' anytime"
+      fi
+    else
+      info "Skipped — sign in later with:  higgsfield auth login"
+    fi
+  else
+    info "Not signed in. Generation needs:  higgsfield auth login"
+  fi
+  info "Pack is off by default — enable:  bash lib/toggle-external.sh enable higgsfield"
+fi
+echo ""
+
 # ============================================================
 # STEP 8.7 — 21ST.DEV CLI + SKILL PACK
 # ============================================================
@@ -1065,13 +1137,13 @@ apply_effort_pins "$REPO" || warn "effort pins: map lines rejected — fix lib/e
 # Auth — detect, then offer login ONLY in an interactive TTY. A non-interactive
 # run (CI / headless / re-run) must never open a browser or block on OAuth.
 # Search and logo lookup are free; retrieving component code and 21st AI need
-# the session. Mirrors the ctx7 auth block (Step 6).
+# the session. Mirrors the ctx7 auth block (Step 6), stdin-only test included.
 if command -v 21st &>/dev/null; then
   # `whoami` is a local token read (no network): "Logged in as <user> (saved …)."
   TFD_WHO="$(21st whoami 2>/dev/null | head -1)"
   if [[ "$TFD_WHO" == "Logged in as "* ]]; then
     ok "21st: ${TFD_WHO%.}"
-  elif [ -t 0 ] && [ -t 1 ]; then
+  elif [ -t 0 ]; then
     printf '%b' "${BLUE}→${NC} Sign in to 21st now? (opens a browser) [y/N] "
     read -r tfd_ans || tfd_ans=""
     if [[ "$tfd_ans" =~ ^[Yy]([Ee][Ss])?$ ]]; then
@@ -1236,6 +1308,7 @@ echo "    🔄 agent-skills trio   — observability-and-instrumentation, deprec
 echo "    🔄 mengto scroll skills — scroll-world-storytelling, build-threejs-scroll-worlds, scroll-scrubbed-visual-sequence, scroll-scrubbed-word-reveal, scroll-progress-timeline (curl → symlink, pinned commit)"
 echo "    🔄 darwin-skill        — autonomous skill optimizer (npx skills, ~/.agents/skills/)"
 echo "    🔄 21st skill pack     — 21st.dev CLI skills; design ones follow the profile (full by default), publishing ones on demand (toggle: lib/toggle-external.sh enable 21st)"
+echo "    🔄 higgsfield pack     — Higgsfield CLI media skills (image, video, audio, brand), OFF by default (toggle: lib/toggle-external.sh enable higgsfield; landing-page aid: enable higgsfield-websites)"
 echo ""
 echo "  All plugins installed at: user scope (~/.claude/plugins/)"
 echo "  GStack skills symlinked individually into ~/.claude/skills/ (→ submodule)"
diff --git a/lib/tests/higgsfield.test.sh b/lib/tests/higgsfield.test.sh
index 4ba5d82..1d6ebf4 100644
--- a/lib/tests/higgsfield.test.sh
+++ b/lib/tests/higgsfield.test.sh
@@ -312,5 +312,29 @@ expect profiles \
 expect pins-map   "$(count lib/effort-pins.txt higgsfield)" 0
 verdict OFF_BY_DEFAULT_WIRING
 
+# ln_first / ln_last <file> <fixed string> — line number of a match.
+ln_first() { grep -nF -- "$2" "$ROOT/$1" | head -1 | cut -d: -f1; }
+ln_last()  { grep -nF -- "$2" "$ROOT/$1" | tail -1 | cut -d: -f1; }
+# shellcheck disable=SC2016  # a literal to grep for, not an expansion
+PINS='apply_effort_pins "$REPO"'
+
+# install-plugins.sh: the sync sits in Step 8.6, before the effort pins
+# (BDR-108); the CLI is proven by a probe, not by its shim; every login
+# offer tests stdin alone (stdout is the tee pipe).
+sync_ln="$(ln_last install-plugins.sh 'higgsfield_sync_skills')"
+expect after-8.5 "$(yn test "$sync_ln" -gt \
+  "$(ln_first install-plugins.sh 'Step 8.5: External skills')")" yes
+expect before-8.7 "$(yn test "$sync_ln" -lt \
+  "$(ln_first install-plugins.sh 'Step 8.7: 21st.dev')")" yes
+expect before-pins "$(yn test "$sync_ln" -lt \
+  "$(ln_last install-plugins.sh "$PINS")")" yes
+expect probe-gates \
+  "$(yn test "$(count install-plugins.sh 'if higgsfield_cli_ok')" -ge 3)" yes
+expect control "$(echo 'if [ -t 0 ] && [ -t 1 ]; then' | grep -cF -- '-t 1')" 1
+expect no-stdout-test "$(count install-plugins.sh '-t 1')" 0
+expect stdin-tests \
+  "$(yn test "$(count install-plugins.sh '[ -t 0 ]')" -ge 3)" yes
+verdict INSTALL_WIRING
+
 # ── tally ───────────────────────────────────────────────────
 printf 'PASS=%s FAIL=%s\n' "$pass" "$fail"; [ "$fail" -eq 0 ]