diff --git a/docs/guides/setup-new-repo.md b/docs/guides/setup-new-repo.md
index a78fa6d..a38e469 100644
--- a/docs/guides/setup-new-repo.md
+++ b/docs/guides/setup-new-repo.md
@@ -147,7 +147,44 @@ Copy `templates/release-drafter.yml` from this repo to `.github/release-drafter.
 
 ---
 
-## 4. Delete old files
+## 4. Dependency ranges on sibling packages (if applicable)
+
+Skip this step if the repo has no dependency on another CAVA package (e.g. `oa-configurator`, which is a base/leaf package with no siblings of its own).
+
+If this repo depends on one or more CAVA sibling packages, prefer a semver range over an exact pin once the sibling has itself migrated to this centralised CI/CD (its releases are label-gated, so MAJOR only happens on a `breaking`-labelled PR):
+
+```toml
+dependencies = [
+    "oa-configurator>=0.1.2,<1.0.0",  # not =="0.1.2"
+]
+```
+
+CI installs with plain `uv sync`, which prefers what's already committed in `uv.lock` but will fail loudly if it no longer satisfies `pyproject.toml`, see [Keeping `uv.lock` in sync](#keeping-uvlock-in-sync) below for how that stays consistent with `pyproject.toml`. Enable **Dependabot security updates** in the repo's settings (Advanced Security) for CVE coverage; no `dependabot.yml` file is needed for that.
+
+---
+
+## 5. Keeping `uv.lock` in sync
+
+`ci.yml` installs with plain `uv sync`. It prefers whatever's already committed in `uv.lock` (so a dependency that's still valid never gets bumped just because something newer shipped upstream), but it re-resolves and fails loudly the moment the lock can no longer satisfy `pyproject.toml`. Confirmed directly against `--frozen` (which blindly trusts the lock with no validation at all, silently passing even when the two have diverged) and `--locked`/`--check` (which fails on any staleness at all, not just genuine inconsistency) before settling on plain `uv sync` as the one mode that does both correctly. That makes it important that `uv.lock` actually reflects `pyproject.toml`, without relying on someone remembering to run `uv lock` after every dependency edit.
+
+Install the canonical pre-commit hook:
+
+```bash
+mkdir -p .githooks
+cp <path-to-cava-devops>/templates/githooks/pre-commit .githooks/pre-commit
+chmod +x .githooks/pre-commit
+git config core.hooksPath .githooks
+```
+
+`git config core.hooksPath` is a one-time, per-clone setting (not committed), so each contributor needs to run it once after cloning.
+
+What it does: when `pyproject.toml` is part of a commit, the hook diffs it to find exactly which dependency line(s) changed, then runs `uv lock --upgrade-package <name>` for just those -- not a blanket `uv lock`. This touches only the package(s) you actually edited (plus whatever *that* package's new version transitively requires), never an unrelated dependency that merely happens to have a newer release available. Confirmed directly: `uv lock --upgrade-package certifi` moved only `certifi`, leaving every other locked package untouched.
+
+This runs locally, before the commit is created. By the time a PR is opened, `uv.lock` is already correct, and CI's `uv sync` install just confirms it.
+
+---
+
+## 6. Delete old files
 
 Remove these files if present in the repo:
 
@@ -161,7 +198,7 @@ Remove these files if present in the repo:
 
 ---
 
-## 5. GitHub configuration
+## 7. GitHub configuration
 
 ### Merge settings
 
@@ -225,7 +262,7 @@ This creates five labels: `breaking`, `feature`, `fix`, `dependencies` (bump lab
 
 ---
 
-## 6. First release after cutover
+## 8. First release after cutover
 
 Merge all migration changes via a PR labelled `chore`. `merge.yml` triggers and release-drafter creates a draft. What to do next depends on whether the repo has existing tags.
 
diff --git a/templates/githooks/pre-commit b/templates/githooks/pre-commit
new file mode 100755
index 0000000..398202d
--- /dev/null
+++ b/templates/githooks/pre-commit
@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+# Canonical CAVA pre-commit hook: keeps uv.lock in sync with pyproject.toml.
+#
+# If pyproject.toml is staged, finds the specific dependency line(s) that
+# changed (added, removed, or had their version spec edited) and refreshes
+# only those packages in uv.lock via `uv lock --upgrade-package`. Does not
+# touch any other package -- this is a targeted sync, not a blanket
+# `uv lock`, so it never pulls in an unrelated upstream release.
+set -euo pipefail
+
+if ! git diff --cached --name-only | grep -q '^pyproject\.toml$'; then
+    exit 0
+fi
+
+if ! command -v uv >/dev/null 2>&1; then
+    echo "pre-commit: uv not found on PATH, skipping uv.lock sync" >&2
+    exit 0
+fi
+
+changed_names=$(git diff --cached -- pyproject.toml \
+    | grep -E '^[+-]\s*"[A-Za-z0-9][A-Za-z0-9._-]*' \
+    | sed -E 's/^[+-]\s*"([A-Za-z0-9][A-Za-z0-9._-]*).*/\1/' \
+    | sort -u)
+
+if [ -z "$changed_names" ]; then
+    exit 0
+fi
+
+upgrade_args=()
+while IFS= read -r name; do
+    upgrade_args+=(--upgrade-package "$name")
+done <<< "$changed_names"
+
+echo "pre-commit: syncing uv.lock for changed dependencies:"
+echo "$changed_names" | sed 's/^/  - /'
+uv lock "${upgrade_args[@]}"
+git add uv.lock