diff --git a/CHANGELOG.md b/CHANGELOG.md
index fda29ea8..a3f6ac23 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,63 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [6.51.1] - 2026-05-20
+
+Hotfix: the install-time skills picker hardcoded a 24-skill list in
+`scripts/lib/skills.sh:SKILLS_CATALOG`, so the 38 marketing skills added
+in v6.51.0 + the humanizer skill added in v6.50.0 were INVISIBLE to the
+TUI even though they were correctly mirrored under
+`templates/skills-marketplace/` and registered in
+`manifest.json:skills_pins` + `templates/skills-catalog.json`.
+
+User-reported regression — the install picker on a fresh project showed
+only the legacy 24 skills, missing all 39 net-new skills from the past
+two ships.
+
+### Fixed
+
+- **`scripts/lib/skills.sh:SKILLS_CATALOG`** — expanded from 24 names to
+  63 (62 mirrored skills + `impeccable` npm-installed special case). The
+  array now matches `manifest.json:files.skills_marketplace` 1:1, plus
+  the `impeccable` entry that lives outside the mirror by design.
+- Updated SKILLS_CATALOG header comment from "24-skill catalog —
+  SKILL-01 source of truth" to a description of the actual contract
+  (mirror dirs + impeccable npm special-case). The vestigial
+  `REQUIREMENTS.md SKILL-01` reference was already dead (no such file).
+- Updated docstring on `skills_catalog_names()` and the variable docs at
+  the top of the file — no more "24" hardcoded references.
+
+### Why this slipped
+
+The previous 3 ships (v6.49.0, v6.50.0, v6.51.0) updated:
+
+- `manifest.json:skills_pins` (62 entries)
+- `manifest.json:files.skills_marketplace` (62 entries)
+- `templates/skills-catalog.json` (61 + memo-skill = 62)
+- mirror dirs under `templates/skills-marketplace/`
+
+… but did NOT update `SKILLS_CATALOG` in `scripts/lib/skills.sh`. That
+array is what `scripts/install.sh` reads when building the TUI checklist
+— it is the single source of truth for picker visibility, separate from
+the manifest/catalog files. The drift was silent because `make check`
+does not enforce SKILLS_CATALOG ↔ manifest consistency.
+
+### Memory correction
+
+The v6.51.0 CHANGELOG + topic file claimed `ab-test-setup` was retained
+from the mysticaltech fork "under a distinct name." Re-audit of
+`manifest.json:skills_pins` shows `ab-test-setup` was never pinned —
+only `analytics-tracking` was kept from mysticaltech. The
+`ab-test-setup` claim was a documentation hallucination. The
+SKILLS_CATALOG fix in this release does NOT add `ab-test-setup`
+because no mirror dir exists for it.
+
+### Follow-up
+
+A future release should add a `make check` gate that compares
+`SKILLS_CATALOG` against `manifest.json:files.skills_marketplace` to
+prevent recurrence. Tracked as deferred work.
+
 ## [6.51.0] - 2026-05-20
 
 Bulk skills-marketplace expansion: 40 marketing skills from the canonical
diff --git a/manifest.json b/manifest.json
index 337f2191..99c42e39 100644
--- a/manifest.json
+++ b/manifest.json
@@ -1,6 +1,6 @@
 {
   "manifest_version": 2,
-  "version": "6.51.0",
+  "version": "6.51.1",
   "updated": "2026-05-20",
   "build_date": "2026-05-20",
   "description": "Claude Code Toolkit manifest for smart updates",
diff --git a/scripts/init-claude.sh b/scripts/init-claude.sh
index b2c35362..38b781e2 100755
--- a/scripts/init-claude.sh
+++ b/scripts/init-claude.sh
@@ -35,7 +35,7 @@ NC='\033[0m'
 # `raw.githubusercontent.com/.../v6.24.5/.../init-claude.sh`), leave
 # TK_TOOLKIT_REF unset and it inherits the bundled default below —
 # guaranteeing every file in the install comes from the same tag.
-TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.0}"
+TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.1}"
 # Audit INF-MED-2 (2026-04-30 deep): allowlist guard — TK_TOOLKIT_REF flows
 # raw into curl URLs. Reject anything outside the tag/SHA charset, plus any
 # `..` traversal sequence. Tags / branches / SHAs do not contain `..`.
diff --git a/scripts/install-statusline.sh b/scripts/install-statusline.sh
index af267313..48d7d3c6 100755
--- a/scripts/install-statusline.sh
+++ b/scripts/install-statusline.sh
@@ -33,7 +33,7 @@ done
 : "${YES}"  # silence shellcheck SC2034 — no-op stub today
 
 # Audit H5: TK_TOOLKIT_REF pins to a tag/SHA (default `main`).
-TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.0}"
+TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.1}"
 # Audit INF-MED-2 (2026-04-30 deep): allowlist guard — TK_TOOLKIT_REF flows
 # raw into curl URLs. Reject anything outside the tag/SHA charset, plus any
 # `..` traversal sequence. Tags / branches / SHAs do not contain `..`.
diff --git a/scripts/install.sh b/scripts/install.sh
index 3f89decc..79a999e1 100644
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -40,7 +40,7 @@ export TK_TOOLKIT_REF TK_USER_AGENT
 # Config
 # Audit H5: TK_TOOLKIT_REF pins to a tag/SHA (default `main`); TK_REPO_URL
 # remains the highest-priority override (full URL with ref baked in).
-TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.0}"
+TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.1}"
 # Audit INF-MED-2 (2026-04-30 deep): allowlist guard — TK_TOOLKIT_REF flows
 # raw into curl URLs. Reject anything outside the tag/SHA charset, plus any
 # `..` traversal sequence. Tags / branches / SHAs do not contain `..`.
@@ -1279,7 +1279,7 @@ fi
 # Mirror of the --mcps branch above; reuses TUI_* globals + print_install_status.
 # ─────────────────────────────────────────────────
 if [[ "$SKILLS" -eq 1 ]]; then
-    # Populate TUI_INSTALLED[] from the 24-skill catalog.
+    # Populate TUI_INSTALLED[] from SKILLS_CATALOG (sourced from scripts/lib/skills.sh).
     skills_status_array
 
     # Build TUI globals from SKILLS_CATALOG.
diff --git a/scripts/lib/skills.sh b/scripts/lib/skills.sh
index d6e453bd..24292adc 100644
--- a/scripts/lib/skills.sh
+++ b/scripts/lib/skills.sh
@@ -3,12 +3,12 @@
 # Claude Code Toolkit — Skills Catalog Loader + Detection + Install Helper (v4.5+)
 # Source this file. Do NOT execute it directly.
 # Exposes:
-#   skills_catalog_names           — prints 24 skill names one-per-line (alpha sorted)
+#   skills_catalog_names           — prints all catalog skill names one-per-line (alpha sorted)
 #   is_skill_installed <name>      — returns 0 (installed) / 1 (not installed)
 #   skills_status_array            — populates TUI_INSTALLED[] for install.sh --skills branch
 #   skills_install <name> [--force] — copies skill from mirror to target via cp -R
 # Globals (write):
-#   SKILLS_CATALOG[]   — 24 curated skill names (alpha order); populated at source time
+#   SKILLS_CATALOG[]   — curated skill names (alpha order); populated at source time
 #   TUI_INSTALLED[]    — populated by skills_status_array (parallel to SKILLS_CATALOG)
 # Test seams:
 #   TK_SKILLS_HOME                    — override $HOME/.claude/skills/ probe path (used by is_skill_installed)
@@ -31,33 +31,75 @@
 # shellcheck disable=SC2034
 [[ -z "${NC:-}"     ]] && NC='\033[0m'
 
-# Curated 24-skill catalog — SKILL-01 source of truth.
-# Alphabetical order. Do NOT add or remove without updating REQUIREMENTS.md SKILL-01.
+# Curated skills catalog — must stay in sync with manifest.json:files.skills_marketplace.
+# Alphabetical order. impeccable is an npm-installed skill (special-cased in
+# _skills_description below) — not vendored under templates/skills-marketplace/.
+# All other names map to a templates/skills-marketplace/<name>/ mirror dir.
+# Total: 63 (62 mirrored skills + impeccable).
 # shellcheck disable=SC2034
 SKILLS_CATALOG=(
+  ab-testing
+  ad-creative
+  ads
   ai-models
+  ai-seo
+  analytics
   analytics-tracking
+  aso
   chrome-extension-development
+  churn-prevention
+  co-marketing
+  cold-email
+  community-marketing
+  competitor-profiling
+  competitors
+  content-strategy
+  copy-editing
   copywriting
+  cro
+  customer-research
+  directory-submissions
   docx
+  emails
   find-skills
   firecrawl
+  free-tools
   huashu-design
+  humanizer
   i18n-localization
+  image
   impeccable
+  launch
+  lead-magnets
+  marketing-ideas
+  marketing-psychology
   memo-skill
   next-best-practices
   notebooklm
+  onboarding
+  paywalls
   pdf
+  popups
+  pricing
+  product-marketing
+  programmatic-seo
+  referrals
   resend
+  revops
+  sales-enablement
+  schema
   seo-audit
   shadcn
+  signup
+  site-architecture
+  social
   stripe-best-practices
   tailwind-design-system
   typescript-advanced-types
   ui-ux-pro-max
   vercel-composition-patterns
   vercel-react-best-practices
+  video
   webapp-testing
 )
 
@@ -74,7 +116,7 @@ _skills_default_mirror_path() {
     echo "${TK_SKILLS_MIRROR_PATH:-${d}/../../templates/skills-marketplace}"
 }
 
-# skills_catalog_names — print all 24 skill names from SKILLS_CATALOG, one per line.
+# skills_catalog_names — print all skill names from SKILLS_CATALOG, one per line.
 skills_catalog_names() {
     printf '%s\n' "${SKILLS_CATALOG[@]}"
 }
diff --git a/scripts/migrate-to-complement.sh b/scripts/migrate-to-complement.sh
index 79ba0fc4..9ef0dcae 100755
--- a/scripts/migrate-to-complement.sh
+++ b/scripts/migrate-to-complement.sh
@@ -57,7 +57,7 @@ CYAN='\033[0;36m'
 NC='\033[0m'
 
 # Audit H5: TK_TOOLKIT_REF pins to a tag/SHA (default `main`).
-TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.0}"
+TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.1}"
 # Audit INF-MED-2 (2026-04-30 deep): allowlist guard — TK_TOOLKIT_REF flows
 # raw into curl URLs. Reject anything outside the tag/SHA charset, plus any
 # `..` traversal sequence. Tags / branches / SHAs do not contain `..`.
diff --git a/scripts/setup-council.sh b/scripts/setup-council.sh
index 6f97084e..527f7968 100644
--- a/scripts/setup-council.sh
+++ b/scripts/setup-council.sh
@@ -16,7 +16,7 @@ CYAN='\033[0;36m'
 NC='\033[0m'
 
 # Audit H5: TK_TOOLKIT_REF pins to a tag/SHA (default `main`).
-TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.0}"
+TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.1}"
 # Audit INF-MED-2 (2026-04-30 deep): allowlist guard — TK_TOOLKIT_REF flows
 # raw into curl URLs. Reject anything outside the tag/SHA charset, plus any
 # `..` traversal sequence. Tags / branches / SHAs do not contain `..`.
diff --git a/scripts/setup-prompt-engineer.sh b/scripts/setup-prompt-engineer.sh
index 0b2fbf5b..cb3e6039 100755
--- a/scripts/setup-prompt-engineer.sh
+++ b/scripts/setup-prompt-engineer.sh
@@ -18,7 +18,7 @@ NC='\033[0m'
 
 # TK_TOOLKIT_REF pins to a tag/SHA (default `main`). Mirrors setup-council.sh
 # to keep allowlist + curl conventions identical.
-TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.0}"
+TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.1}"
 if ! [[ "$TK_TOOLKIT_REF" =~ ^[A-Za-z0-9._/-]+$ ]] || [[ "$TK_TOOLKIT_REF" == *..* ]]; then
     echo "Error: TK_TOOLKIT_REF must match [A-Za-z0-9._/-]+ and must not contain '..' (got: $TK_TOOLKIT_REF)" >&2
     exit 1
diff --git a/scripts/setup-security.sh b/scripts/setup-security.sh
index 85b333ca..f34d3176 100755
--- a/scripts/setup-security.sh
+++ b/scripts/setup-security.sh
@@ -46,7 +46,7 @@ done
 : "${YES}"  # silence shellcheck SC2034 — YES consumed by future read blocks
 
 # Audit H5: TK_TOOLKIT_REF pins to a tag/SHA (default `main`).
-TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.0}"
+TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.1}"
 # Audit INF-MED-2 (2026-04-30 deep): allowlist guard — TK_TOOLKIT_REF flows
 # raw into curl URLs. Reject anything outside the tag/SHA charset, plus any
 # `..` traversal sequence. Tags / branches / SHAs do not contain `..`.
diff --git a/scripts/tests/test-install-skills.sh b/scripts/tests/test-install-skills.sh
index a037989a..d4133d2a 100755
--- a/scripts/tests/test-install-skills.sh
+++ b/scripts/tests/test-install-skills.sh
@@ -2,16 +2,16 @@
 # test-install-skills.sh — Phase 26 hermetic integration test.
 #
 # Scenarios (target ≥12 assertions across 6 scenarios):
-#   S1_catalog_correctness   — SKILLS_CATALOG has 24 entries; alphabetical order
+#   S1_catalog_correctness   — SKILLS_CATALOG has 63 entries; alphabetical order
 #   S2_detection_two_state   — is_skill_installed returns 0 (installed) / 1 (not installed)
 #   S3_skills_install_basic  — skills_install copies one skill from mirror to TK_SKILLS_HOME via cp -R
 #   S4_idempotency_no_force  — re-running skills_install on installed skill returns rc=2 (refused, no overwrite)
 #   S5_force_overwrite       — skills_install --force on installed skill returns rc=0 (overwritten)
-#   S6_install_sh_dry_run    — install.sh --skills --yes --dry-run produces 24 would-install rows; zero filesystem mutations
+#   S6_install_sh_dry_run    — install.sh --skills --yes --dry-run produces 63 would-install rows; zero filesystem mutations
 #
 # Test seam env vars: TK_SKILLS_HOME, TK_SKILLS_MIRROR_PATH, TK_TUI_TTY_SRC
 #
-# Sample skills used in scenarios (3 of 24, per CONTEXT.md test strategy):
+# Sample skills used in scenarios (3 of 63, per CONTEXT.md test strategy):
 #   ai-models, pdf, tailwind-design-system
 #
 # Usage: bash scripts/tests/test-install-skills.sh
@@ -59,17 +59,17 @@ echo "test-install-skills.sh: SKILL-03..05 hermetic suite"
 echo ""
 
 # ─────────────────────────────────────────────────
-# S1_catalog_correctness — SKILLS_CATALOG has 24 entries; alphabetical order
+# S1_catalog_correctness — SKILLS_CATALOG has 63 entries; alphabetical order
 # SKILL-01
 # ─────────────────────────────────────────────────
 run_s1_catalog_correctness() {
-    echo "  -- S1_catalog_correctness: 24 entries, alphabetical order, last is webapp-testing --"
+    echo "  -- S1_catalog_correctness: 63 entries, alphabetical order, first ab-testing, last webapp-testing --"
     SKILLS_CATALOG=()
     # shellcheck source=/dev/null
     source "${REPO_ROOT}/scripts/lib/skills.sh"
-    assert_eq "24" "${#SKILLS_CATALOG[@]}" "S1: catalog contains 24 entries"
-    assert_eq "ai-models" "${SKILLS_CATALOG[0]}" "S1: alphabetical first entry is ai-models"
-    assert_eq "webapp-testing" "${SKILLS_CATALOG[23]}" "S1: alphabetical last entry is webapp-testing"
+    assert_eq "63" "${#SKILLS_CATALOG[@]}" "S1: catalog contains 63 entries"
+    assert_eq "ab-testing" "${SKILLS_CATALOG[0]}" "S1: alphabetical first entry is ab-testing"
+    assert_eq "webapp-testing" "${SKILLS_CATALOG[62]}" "S1: alphabetical last entry is webapp-testing"
 }
 
 # ─────────────────────────────────────────────────
@@ -289,7 +289,7 @@ run_s5_force_overwrite() {
 }
 
 # ─────────────────────────────────────────────────
-# S6_install_sh_dry_run — --skills --yes --dry-run: 24 would-install rows, zero mutations (SKILL-05)
+# S6_install_sh_dry_run — --skills --yes --dry-run: 63 would-install rows, zero mutations (SKILL-05)
 # ─────────────────────────────────────────────────
 run_s6_install_sh_dry_run() {
     local SANDBOX
@@ -313,7 +313,7 @@ run_s6_install_sh_dry_run() {
 
     local would_count
     would_count=$(printf '%s\n' "$output" | grep -c "would-install" || true)
-    assert_eq "24" "$would_count" "S6: dry-run prints 24 would-install rows"
+    assert_eq "63" "$would_count" "S6: dry-run prints 63 would-install rows"
 
     # Zero filesystem mutations: SKILLS_HOME should still be empty.
     local file_count
diff --git a/scripts/uninstall.sh b/scripts/uninstall.sh
index e4d6b3c3..7ee5e71e 100755
--- a/scripts/uninstall.sh
+++ b/scripts/uninstall.sh
@@ -104,7 +104,7 @@ fi
 
 # ───────── constants + log helpers ─────────
 # Audit H5: TK_TOOLKIT_REF pins to a tag/SHA (default `main`).
-TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.0}"
+TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.1}"
 # Audit INF-MED-2 (2026-04-30 deep): allowlist guard — TK_TOOLKIT_REF flows
 # raw into curl URLs. Reject anything outside the tag/SHA charset, plus any
 # `..` traversal sequence. Tags / branches / SHAs do not contain `..`.
diff --git a/scripts/update-claude.sh b/scripts/update-claude.sh
index 7dc93520..d52990b2 100755
--- a/scripts/update-claude.sh
+++ b/scripts/update-claude.sh
@@ -73,7 +73,7 @@ CYAN='\033[0;36m'
 NC='\033[0m'
 
 # Audit H5: TK_TOOLKIT_REF pins to a tag/SHA (default `main`).
-TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.0}"
+TK_TOOLKIT_REF="${TK_TOOLKIT_REF:-v6.51.1}"
 # Audit INF-MED-2 (2026-04-30 deep): allowlist guard — TK_TOOLKIT_REF flows
 # raw into curl URLs. Reject anything outside the tag/SHA charset, plus any
 # `..` traversal sequence. Tags / branches / SHAs do not contain `..`.