diff --git a/.claude/hooks/gate-lib.sh b/.claude/hooks/gate-lib.sh
new file mode 100755
index 0000000..e94dd61
--- /dev/null
+++ b/.claude/hooks/gate-lib.sh
@@ -0,0 +1,108 @@
+#!/usr/bin/env bash
+# .claude/hooks/gate-lib.sh — shared quality-gate detection library.
+#
+# Single responsibility (artifacts/plan_framework_hardening.md, unit U5a):
+# given a project directory, detect which quality gates apply and emit, per
+# detected gate, an INVOCABLE command string plus the short human label the
+# pre-commit advisory has always shown. Detection lives here once; each
+# caller decides what to DO with a gate — today, pre-commit-verification.sh
+# only reads the labels for its advisory text; a later enforcement hook can
+# read GATE_COMMANDS to actually run them (open/closed — plan's Design
+# Principles).
+#
+# Usage:
+#   # shellcheck source=gate-lib.sh
+#   source ".../gate-lib.sh"
+#   gate_lib_detect "$PROJECT_DIR"
+#   # then read the parallel arrays it populates:
+#   #   GATE_LABELS[i]    human label, unchanged wording, e.g. "lint(pnpm)"
+#   #   GATE_COMMANDS[i]  invocable command, e.g. "pnpm run lint"
+#
+# Adapting: add a stack by appending one `if [ -f "$dir/<manifest>" ]` block
+# with its own `_gate_add` calls — never by editing an existing block.
+#
+# Sourced, not executed directly — deliberately does not `set -u` itself
+# (that would silently change the sourcing script's shell options too).
+# Every variable below is defensively initialized so this stays correct
+# under a caller's own `set -u` regardless.
+
+GATE_LABELS=()
+GATE_COMMANDS=()
+
+_gate_add() { # $1=label $2=command
+  GATE_LABELS+=("$1")
+  GATE_COMMANDS+=("$2")
+}
+
+# gate_lib_detect DIR — populate GATE_LABELS/GATE_COMMANDS for DIR.
+# Re-runnable: resets both arrays on every call.
+gate_lib_detect() {
+  local dir="${1:?gate_lib_detect: project dir required}"
+  GATE_LABELS=()
+  GATE_COMMANDS=()
+
+  # TypeScript/JavaScript (pnpm preferred per tech strategy)
+  if [ -f "$dir/package.json" ]; then
+    local pkg_mgr
+    if [ -f "$dir/pnpm-lock.yaml" ]; then
+      pkg_mgr="pnpm"
+    elif [ -f "$dir/package-lock.json" ]; then
+      pkg_mgr="npm"
+    else
+      pkg_mgr="pnpm"
+    fi
+
+    if grep -q '"lint"' "$dir/package.json" 2>/dev/null; then
+      _gate_add "lint($pkg_mgr)" "$pkg_mgr run lint"
+    fi
+    if grep -q '"test"' "$dir/package.json" 2>/dev/null; then
+      _gate_add "test($pkg_mgr)" "$pkg_mgr test"
+    fi
+    if grep -q '"typecheck\|"tsc\|"type-check"' "$dir/package.json" 2>/dev/null; then
+      _gate_add "typecheck($pkg_mgr)" "$pkg_mgr run typecheck"
+    fi
+
+    # Biome (preferred per tech strategy) — its own invocable check,
+    # independent of whether a package.json "lint" script also exists.
+    if [ -f "$dir/biome.json" ] || [ -f "$dir/biome.jsonc" ]; then
+      _gate_add "biome" "$pkg_mgr exec biome check ."
+    fi
+  fi
+
+  # Python (uv preferred per tech strategy)
+  if [ -f "$dir/pyproject.toml" ]; then
+    local py_run
+    if command -v uv >/dev/null 2>&1; then
+      py_run="uv run"
+    else
+      py_run="python -m"
+    fi
+
+    if grep -q "ruff" "$dir/pyproject.toml" 2>/dev/null; then
+      _gate_add "ruff" "$py_run ruff check ."
+    fi
+    if grep -q "pytest" "$dir/pyproject.toml" 2>/dev/null; then
+      _gate_add "pytest" "$py_run pytest"
+    fi
+    if grep -q "mypy" "$dir/pyproject.toml" 2>/dev/null; then
+      _gate_add "mypy" "$py_run mypy ."
+    fi
+  fi
+
+  # Go
+  if [ -f "$dir/go.mod" ]; then
+    _gate_add "go-test" "go test ./..."
+    _gate_add "go-vet" "go vet ./..."
+
+    if command -v golangci-lint >/dev/null 2>&1 || [ -f "$dir/.golangci.yml" ]; then
+      _gate_add "golangci-lint" "golangci-lint run"
+    fi
+  fi
+
+  # Rust
+  if [ -f "$dir/Cargo.toml" ]; then
+    _gate_add "cargo-test" "cargo test"
+    _gate_add "cargo-clippy" "cargo clippy"
+    _gate_add "cargo-fmt" "cargo fmt --check"
+  fi
+}
diff --git a/.claude/hooks/pre-commit-verification.sh b/.claude/hooks/pre-commit-verification.sh
index b4fc778..c180acb 100755
--- a/.claude/hooks/pre-commit-verification.sh
+++ b/.claude/hooks/pre-commit-verification.sh
@@ -41,68 +41,22 @@ if [ -f "$VERIFICATION_FILE" ]; then
     fi
 fi
 
-# Detect project type and available tools
-DETECTED_TOOLS=""
-
-# TypeScript/JavaScript (pnpm preferred per tech strategy)
-if [ -f "$PROJECT_DIR/package.json" ]; then
-    if [ -f "$PROJECT_DIR/pnpm-lock.yaml" ]; then
-        PKG_MGR="pnpm"
-    elif [ -f "$PROJECT_DIR/package-lock.json" ]; then
-        PKG_MGR="npm"
-    else
-        PKG_MGR="pnpm"
-    fi
-
-    # Check for scripts in package.json
-    if grep -q '"lint"' "$PROJECT_DIR/package.json" 2>/dev/null; then
-        DETECTED_TOOLS="$DETECTED_TOOLS lint($PKG_MGR)"
-    fi
-    if grep -q '"test"' "$PROJECT_DIR/package.json" 2>/dev/null; then
-        DETECTED_TOOLS="$DETECTED_TOOLS test($PKG_MGR)"
-    fi
-    if grep -q '"typecheck\|"tsc\|"type-check"' "$PROJECT_DIR/package.json" 2>/dev/null; then
-        DETECTED_TOOLS="$DETECTED_TOOLS typecheck($PKG_MGR)"
-    fi
-
-    # Biome (preferred per tech strategy)
-    if [ -f "$PROJECT_DIR/biome.json" ] || [ -f "$PROJECT_DIR/biome.jsonc" ]; then
-        DETECTED_TOOLS="$DETECTED_TOOLS biome"
-    fi
-fi
-
-# Python (uv preferred per tech strategy)
-if [ -f "$PROJECT_DIR/pyproject.toml" ]; then
-    # Ruff (preferred per tech strategy)
-    if grep -q "ruff" "$PROJECT_DIR/pyproject.toml" 2>/dev/null; then
-        DETECTED_TOOLS="$DETECTED_TOOLS ruff"
-    fi
+# Detect project type and available gates — detection lives in gate-lib.sh
+# (artifacts/plan_framework_hardening.md, unit U5a): one shared function
+# emits invocable commands per gate; this hook only needs the human labels
+# for its advisory text below, reconstructed here in the same order and
+# format ("<label>" tokens space-joined) as before the extraction, so the
+# advisory output stays byte-identical.
+# shellcheck source=gate-lib.sh
+# shellcheck disable=SC1091  # dynamic path (BASH_SOURCE-relative); the
+# above source= directive documents it for anyone re-running with `-x`
+source "$(dirname "${BASH_SOURCE[0]}")/gate-lib.sh"
+gate_lib_detect "$PROJECT_DIR"
 
-    # pytest
-    if grep -q "pytest" "$PROJECT_DIR/pyproject.toml" 2>/dev/null; then
-        DETECTED_TOOLS="$DETECTED_TOOLS pytest"
-    fi
-
-    # mypy
-    if grep -q "mypy" "$PROJECT_DIR/pyproject.toml" 2>/dev/null; then
-        DETECTED_TOOLS="$DETECTED_TOOLS mypy"
-    fi
-fi
-
-# Go
-if [ -f "$PROJECT_DIR/go.mod" ]; then
-    DETECTED_TOOLS="$DETECTED_TOOLS go-test go-vet"
-
-    # golangci-lint (preferred per tech strategy)
-    if command -v golangci-lint &> /dev/null || [ -f "$PROJECT_DIR/.golangci.yml" ]; then
-        DETECTED_TOOLS="$DETECTED_TOOLS golangci-lint"
-    fi
-fi
-
-# Rust
-if [ -f "$PROJECT_DIR/Cargo.toml" ]; then
-    DETECTED_TOOLS="$DETECTED_TOOLS cargo-test cargo-clippy cargo-fmt"
-fi
+DETECTED_TOOLS=""
+for _gate_label in "${GATE_LABELS[@]}"; do
+    DETECTED_TOOLS="$DETECTED_TOOLS $_gate_label"
+done
 
 # Build verification context message
 cat << EOF
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 410ac25..025c30a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - New `rules-lines` CI invariant (check #22, `scripts/check-invariants.sh`): sums `.claude/rules/*.md` line counts, excluding any file whose frontmatter carries a `paths:` key (load-on-demand, not always-loaded), against a 500-line budget — measured 409 lines at implementation time. `docs/customization.md`'s "Adding a Rule" section gains a three-tier table (always-loaded rule / `paths:`-scoped rule / skill) documenting the budget and native `paths:` frontmatter mechanism (unit U8)
 - `.claude/rules/hooks-conventions.md`: the framework's first `paths:`-scoped rule (`.claude/hooks/**`, `scripts/**`), dogfooding the tier documented in U8 — shell baseline (`set -u`, shellcheck/`bash -n`, ≤~120 LOC), the fail-open-visibly pattern, the field-scoped `sed` stdin-extraction idiom (citing `branch-pr-discipline.sh`), and the deny/ask JSON output contract. Excluded from `rules-lines`' budget by design (verified: 409 lines counted with the `paths:` frontmatter intact vs. 473 if it were stripped). `docs/customization.md` links it as the tier table's worked example and notes stack packs may use the same mechanism (unit U12)
 - REVIEW.md freshness contract: `review-steering/SKILL.md`'s generation workflow gains step 8, stamping REVIEW.md's final line with `<!-- rules-hash: <hash> -->` (`cat .claude/rules/code-quality.md .claude/rules/security.md | shasum -a 256 | cut -d' ' -f1`); its Refresh Discipline section now cites the mechanical check instead of an unenforced "must never contradict" assertion. New `review-freshness` CI invariant (check #23, `scripts/check-invariants.sh`) recomputes and compares the hash for a tracked root `REVIEW.md`, failing on a missing or stale footer; skips cleanly (this repo ships no REVIEW.md today) when none is tracked (unit U6)
+- `.claude/hooks/gate-lib.sh`: new shared stack-detection library — one `gate_lib_detect` function replaces `pre-commit-verification.sh`'s inline per-stack block, emitting an INVOCABLE command (e.g. `pnpm run lint`, `uv run pytest`, `go test ./...`, `cargo clippy`) alongside the exact human label the pre-commit advisory already showed, per detected TS/JS (package-manager-aware)/Python/Go/Rust gate. `pre-commit-verification.sh` now sources the lib and reconstructs its advisory text from the labels — verified byte-identical stdout across TS/npm/Python/Go/Rust fixtures pre- and post-refactor; pure structure, zero behavior change (Two Hats). Lib's `test(pnpm)` command smoke-tested against `scripts/fixtures/failing-project/`, confirmed nonzero (unit U5a)
 
 ## [4.0.0] - 2026-07-23