diff --git a/install-plugins.sh b/install-plugins.sh
index 2810f4d..60d79e6 100644
--- a/install-plugins.sh
+++ b/install-plugins.sh
@@ -654,6 +654,35 @@ if command -v graphify &>/dev/null; then
 fi
 echo ""
 
+# ============================================================
+# STEP 7.5 — SEMGREP (SAST engine for the security gate)
+# ============================================================
+echo "── Step 7.5: Semgrep — SAST security gate ───────────────────"
+echo ""
+if command -v semgrep &>/dev/null; then
+  ok "semgrep already installed ($(semgrep --version 2>/dev/null | head -1))"
+else
+  SEMGREP_VER=$(pinned_version "semgrep")
+  if [ "$SEMGREP_VER" != "latest" ]; then
+    info "Installing semgrep ${SEMGREP_VER} (pinned in plugins.lock.json)..."
+    pipx install "semgrep==${SEMGREP_VER}" 2>/dev/null
+  else
+    info "Installing semgrep latest (consider pinning in plugins.lock.json)..."
+    pipx install semgrep 2>/dev/null
+  fi
+  if command -v semgrep &>/dev/null; then
+    ok "semgrep installed ($(semgrep --version 2>/dev/null | head -1))"
+  else
+    err "semgrep install failed — run manually: pipx install semgrep"
+  fi
+fi
+# Login is Pro-rules only and optional — NEVER run automatically (ctx7
+# pattern: guide, don't block). The gate uses pinned public rulesets.
+if command -v semgrep &>/dev/null; then
+  info "Optional Pro rules:  semgrep login   (never run automatically)"
+fi
+echo ""
+
 # ============================================================
 # STEP 8 — EMIL DESIGN ENG (UI polish / animation skill)
 # ============================================================
diff --git a/plugins.lock.json b/plugins.lock.json
index ef55a07..f42e496 100644
--- a/plugins.lock.json
+++ b/plugins.lock.json
@@ -26,6 +26,12 @@
     "managed_by": "pipx",
     "note": "Codebase knowledge graph. CLI is 'graphify'. Install: pipx install graphifyy && graphify install && graphify claude install. Adds PreToolUse hook for Glob/Grep."
   },
+  "semgrep": {
+    "source": "pypi:semgrep",
+    "version": "1.168.0",
+    "managed_by": "pipx",
+    "note": "SAST engine for the security gate (security-auditor agent, onboard cso fallback, audit-delta). Rulesets pinned in-agent: p/security-audit + p/secrets (never --config auto). BLOCKING gate -> pin honored by update-all.sh: 'make update' will NOT advance semgrep past it; bump deliberately (new rules = new BLOCKs on unchanged code). Never run 'semgrep login' automatically (Pro rules are optional, guide-only)."
+  },
   "emil-design-eng": {
     "source": "https://github.com/emilkowalski/skill",
     "path": "skills/emil-design-eng/SKILL.md",
diff --git a/update-all.sh b/update-all.sh
index 0eed297..09f7b0c 100644
--- a/update-all.sh
+++ b/update-all.sh
@@ -227,6 +227,47 @@ else
   info "graphifyy not installed — skipping"
 fi
 
+# ── 6.2. Update Semgrep (pin-honored — BLOCKING security gate) ──
+echo ""
+echo "── Updating Semgrep..."
+if command -v semgrep &>/dev/null; then
+  SEMGREP_VER=""
+  if [ -f "$REPO/plugins.lock.json" ] && command -v python3 &>/dev/null; then
+    SEMGREP_VER=$(python3 -c "
+import json
+with open('$REPO/plugins.lock.json') as f:
+    d = json.load(f)
+print(d.get('semgrep',{}).get('version',''))
+" 2>/dev/null || true)
+  fi
+
+  SEMGREP_CUR=$(semgrep --version 2>/dev/null | head -1)
+  if [ -n "$SEMGREP_VER" ] && [ "$SEMGREP_VER" != "latest" ]; then
+    if [ "$SEMGREP_CUR" = "$SEMGREP_VER" ]; then
+      ok "semgrep already at pinned $SEMGREP_VER"
+    else
+      # Jump shown explicitly: semgrep is a BLOCKING gate — a version bump
+      # can add rules that BLOCK unchanged code, so the jump must be a
+      # visible, deliberate human decision (bump the pin, then update).
+      info "semgrep ${SEMGREP_CUR:-?} → ${SEMGREP_VER} (pinned in plugins.lock.json)"
+      if pipx install --force "semgrep==${SEMGREP_VER}" 2>/dev/null; then
+        ok "semgrep updated to $SEMGREP_VER"
+      else
+        warn "semgrep update failed — try: pipx install --force semgrep==${SEMGREP_VER}"
+      fi
+    fi
+  else
+    info "No pinned version — upgrading to latest"
+    if pipx upgrade semgrep 2>/dev/null; then
+      ok "semgrep updated ($(semgrep --version 2>/dev/null | head -1))"
+    else
+      warn "semgrep update failed — try: pipx upgrade semgrep"
+    fi
+  fi
+else
+  info "semgrep not installed — skipping (run: make plugin)"
+fi
+
 # ── 6.5. Update bun ──
 echo ""
 echo "── Updating bun..."