diff --git a/.github/workflows/validate.yml b/.github/workflows/validate.yml
index e2cfe21..12d20f4 100644
--- a/.github/workflows/validate.yml
+++ b/.github/workflows/validate.yml
@@ -14,27 +14,14 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  lock:
-    runs-on: ubuntu-latest
-    timeout-minutes: 5
-    steps:
-      - name: Check out repository
-        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-
-      - name: Install uv
-        uses: astral-sh/setup-uv@c18668ad3cf93ea998bef934396af7bb5c839dc7 # v10.2.0
-        with:
-          version: "0.12.19"
-
-      - name: Lock files match pyproject.toml
-        run: make lock-check
-
+  # Lowest and latest supported CPython; the universal lock already resolves
+  # every version between them, so the middle ones ran the identical suite.
   validate:
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.11", "3.12", "3.13", "3.14"]
+        python-version: ["3.11", "3.14"]
     timeout-minutes: 15
     steps:
       - name: Check out repository
@@ -49,33 +36,14 @@ jobs:
       - name: Set up Python ${{ matrix.python-version }}
         run: uv python install ${{ matrix.python-version }}
 
-      - name: Install dependencies and dev tools
+      - name: Install locked dev dependencies
         run: |
           uv venv --python ${{ matrix.python-version }}
           uv pip install -r requirements-dev.lock.txt
 
-      - name: Lint with ruff
-        run: .venv/bin/ruff check .
-
-      - name: Run tests
-        run: .venv/bin/python -m pytest
-
-      - name: Validate catalog
-        run: .venv/bin/python tools/validate_catalog.py
-
-      - name: Verify public JSON exports
-        run: .venv/bin/python tools/export_catalog.py --check --target both
+      - name: Run all checks
+        run: make check PYTHON=.venv/bin/python
 
-      - name: Verify browsable README indexes
-        run: .venv/bin/python tools/render_readmes.py --check
-
-      - name: Verify first-party content manifest
-        run: .venv/bin/python tools/build_content_manifest.py --check
-
-      - name: Verify runnable examples
-        run: .venv/bin/python tools/verify_examples.py
-
-      - name: Verify course folders
-        run: .venv/bin/python tools/verify_courses.py
-      - name: Verify learning-path contracts
-        run: .venv/bin/python tools/verify_paths.py
+      - name: Lock files match pyproject.toml
+        if: matrix.python-version == '3.11'
+        run: make lock-check
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7ada1d7..43692b8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,13 +10,16 @@ This file records notable catalog-contract and maintenance changes.
   by `make lock` (`uv pip compile --universal` from the Python 3.11 floor)
   instead of hand-maintained. All existing pins were kept; the Windows-only
   `colorama` and Python <3.13 `typing-extensions` transitive pins the manual
-  lock had missed are now included. A new `lock` CI job runs
-  `make lock-check` and fails when the locks drift from `pyproject.toml`.
+  lock had missed are now included. `make lock-check` re-resolves the
+  committed locks in place and fails on any diff; CI runs it on the 3.11 leg.
 - New `tests/test_dependency_pins.py`: every course/path `requirements.txt`
   must pin exactly the versions CI tests with.
-- Validate matrix adds Python 3.14 and no longer cancels sibling versions
-  on the first failure; actions are pinned to commit SHAs, `setup-uv` moves
-  from v7 to v10.2.0, and CI pins uv 0.12.19.
+- Validate is a single `make check` job (the same command as local) on the
+  Python floor and latest (3.11 + 3.14 — the universal lock resolves every
+  version between), no longer cancels sibling versions on the first failure,
+  SHA-pins actions, moves `setup-uv` v7 → v10.2.0, and pins uv 0.12.19.
+- Removed the unused root `requirements.txt` and `requirements-dev.txt`;
+  dependencies are declared only in `pyproject.toml` and the two locks.
 - Removed `notify-site.yml`: its `WEBSITE_SYNC_TOKEN` secret was never
   configured, so all 32 runs skipped the dispatch step while reporting
   success, and the website builds from its own content pin regardless.
diff --git a/Makefile b/Makefile
index 19da60c..c43b2e6 100644
--- a/Makefile
+++ b/Makefile
@@ -64,15 +64,12 @@ paths:
 lock:
 	$(compile_locks)
 
-# Re-resolve copies of the committed locks in a scratch directory: uv keeps
-# every committed pin that still satisfies pyproject.toml, so any diff means
-# the locks drifted from the declared dependencies.
+# uv keeps every committed pin that still satisfies pyproject.toml, so any
+# diff after re-resolution means the locks drifted — the printed diff is the
+# change to commit.
 lock-check:
-	@tmp=$$(mktemp -d) && \
-	cp pyproject.toml requirements.lock.txt requirements-dev.lock.txt "$$tmp/" && \
-	$(MAKE) --no-print-directory -C "$$tmp" -f "$(CURDIR)/Makefile" lock && \
-	diff -u requirements.lock.txt "$$tmp/requirements.lock.txt" && \
-	diff -u requirements-dev.lock.txt "$$tmp/requirements-dev.lock.txt" && \
-	rm -rf "$$tmp" && echo "lock files match pyproject.toml"
+	@$(compile_locks)
+	@git diff --exit-code requirements.lock.txt requirements-dev.lock.txt || \
+		{ echo "lock files drifted from pyproject.toml — commit the regenerated files"; exit 1; }
 
 all: export render manifest check
diff --git a/requirements-dev.txt b/requirements-dev.txt
deleted file mode 100644
index 2137822..0000000
--- a/requirements-dev.txt
+++ /dev/null
@@ -1,5 +0,0 @@
--r requirements.txt
-pytest==9.1.1
-jsonschema>=4.20.0
-pandas==2.3.3
-matplotlib==3.10.9
diff --git a/requirements.txt b/requirements.txt
deleted file mode 100644
index 3d356f2..0000000
--- a/requirements.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-PyYAML==6.0.3
-requests==2.34.2
-urllib3==2.8.0