diff --git a/CLAUDE.md b/CLAUDE.md
index ab227d6..557f00b 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -43,13 +43,33 @@ Universal development practices for all Svrnty/a-gent repositories.
 
 ## Commit Rules
 
-All AI-authored commits MUST use:
+### Allowed Authors
+Only these emails are permitted for commits:
+- `jp@svrnty.io` (Jean-Philippe Brule)
+- `mathias@svrnty.io` (Mathias Beaulieu-Duncan)
+
+Configure with: `git config user.email jp@svrnty.io`
+
+### AI-Assisted Commits
+All AI-authored commits MUST include:
 ```
-Co-Authored-By: Svrnty Inc. <eng@svrnty.com>
+Co-Authored-By: Svrnty Inc. <jp@svrnty.io>
 ```
 
 NEVER use third-party AI tool/company names in commits.
 
+### Git Hooks Setup
+Install lefthook to enforce commit standards:
+```bash
+brew install lefthook
+lefthook install
+```
+
+The hooks automatically:
+- Validate author email is in allowed list
+- Append Co-Authored-By footer
+- Warn on conventional commit format violations
+
 ## PR Discipline
 
 - Clear, scoped commit messages
@@ -73,7 +93,7 @@ Run before every commit:
 
 ## Cross-Repo Changes
 
-When changes span multiple repos:
-1. Commit to each repo separately
-2. Reference related repo in commit message
-3. Run tests in each affected repo before commit
+- Each repo is standalone with its own build configuration
+- Reference related repos in commit messages for cross-repo changes
+- Coordinate multi-repo changes via matching branch names
+- Test each repo independently before pushing
diff --git a/lefthook.yml b/lefthook.yml
new file mode 100644
index 0000000..3f358b3
--- /dev/null
+++ b/lefthook.yml
@@ -0,0 +1,63 @@
+pre-commit:
+  parallel: true
+  commands:
+    check-author:
+      run: |
+        EMAIL=$(git config user.email)
+        ALLOWED="jp@svrnty.io mathias@svrnty.io"
+        for a in $ALLOWED; do
+          [ "$EMAIL" = "$a" ] && exit 0
+        done
+        echo "BLOCKED: author email '$EMAIL' not in allowed list: $ALLOWED"
+        exit 1
+    no-secrets:
+      run: |
+        BLOCKED=$(git diff --cached --name-only | grep -E '\.(env|pem|key)$|credentials\.json|id_rsa|id_ed25519' || true)
+        if [ -n "$BLOCKED" ]; then
+          echo "BLOCKED: refusing to commit sensitive files:"
+          echo "$BLOCKED"
+          exit 1
+        fi
+    no-large-files:
+      run: |
+        LARGE=$(git diff --cached --name-only -z | xargs -0 -I{} sh -c 'if [ -f "{}" ]; then size=$(wc -c < "{}"); if [ "$size" -gt 5242880 ]; then echo "{} ($(( size / 1048576 ))MB)"; fi; fi' || true)
+        if [ -n "$LARGE" ]; then
+          echo "WARNING: large files staged (>5MB):"
+          echo "$LARGE"
+        fi
+
+commit-msg:
+  commands:
+    validate-message:
+      run: |
+        MSG=$(cat "{1}")
+        if echo "$MSG" | head -1 | grep -qE '^Merge '; then
+          exit 0
+        fi
+        if ! echo "$MSG" | head -1 | grep -qE '^[a-z]+(\([a-zA-Z0-9_-]+\))?: .+'; then
+          echo "WARNING: commit message does not follow conventional format: type(scope): message"
+        fi
+    append-coauthor:
+      run: |
+        MSG=$(cat "{1}")
+        if ! echo "$MSG" | grep -qF 'Co-Authored-By: Svrnty Inc. <jp@svrnty.io>'; then
+          printf '\n\nCo-Authored-By: Svrnty Inc. <jp@svrnty.io>\n' >> "{1}"
+        fi
+
+pre-push:
+  commands:
+    protect-main:
+      run: |
+        BRANCH=$(git rev-parse --abbrev-ref HEAD)
+        if [ "$BRANCH" = "main" ] || [ "$BRANCH" = "master" ]; then
+          echo "BLOCKED: direct push to $BRANCH is not allowed"
+          exit 1
+        fi
+    check-behind-remote:
+      run: |
+        git fetch origin 2>/dev/null || true
+        BRANCH=$(git rev-parse --abbrev-ref HEAD)
+        BEHIND=$(git rev-list --count HEAD..origin/"$BRANCH" 2>/dev/null || echo 0)
+        if [ "$BEHIND" -gt 0 ]; then
+          echo "WARNING: local branch is $BEHIND commit(s) behind origin/$BRANCH"
+        fi