diff --git a/.github/workflows/cd-cdk.yaml b/.github/workflows/cd-cdk.yaml
index 53a5a27..2aed4c6 100644
--- a/.github/workflows/cd-cdk.yaml
+++ b/.github/workflows/cd-cdk.yaml
@@ -6,7 +6,7 @@ on:
       node-version:
         description: "Node.js version to use"
         type: string
-        default: "22"
+        default: "24"
       python-version:
         description: "Python version for Python CDK repos (leave empty for TypeScript CDK)"
         type: string
@@ -23,6 +23,10 @@ on:
         description: "Enable QEMU for cross-platform Docker builds (arm64 on x86 runners)"
         type: boolean
         default: false
+      stack-name:
+        description: "CloudFormation stack name (for pre-flight checks)"
+        type: string
+        default: ""
     secrets:
       deploy-role-arn:
         description: "OIDC deploy role ARN"
@@ -67,6 +71,57 @@ jobs:
           role-to-assume: ${{ secrets.deploy-role-arn }}
           aws-region: ${{ inputs.region }}
 
+      - name: Pre-flight checks
+        if: ${{ inputs.stack-name != '' }}
+        run: |
+          echo "Pre-flight: checking stack ${{ inputs.stack-name }}..."
+          STATUS=$(aws cloudformation describe-stacks \
+            --stack-name "${{ inputs.stack-name }}" \
+            --query 'Stacks[0].StackStatus' --output text 2>/dev/null || echo "NOT_FOUND")
+          case "$STATUS" in
+            *ROLLBACK_COMPLETE|*FAILED)
+              echo "::error::Stack ${{ inputs.stack-name }} is in $STATUS — manual intervention required."
+              exit 1
+              ;;
+            *IN_PROGRESS)
+              echo "::error::Stack ${{ inputs.stack-name }} has an operation in progress ($STATUS) — wait for it to complete."
+              exit 1
+              ;;
+            NOT_FOUND)
+              echo "Pre-flight: stack not found — will be created on first deploy."
+              ;;
+            *)
+              echo "Pre-flight: stack status is $STATUS — OK to deploy."
+              ;;
+          esac
+
       - name: CDK deploy
         working-directory: ${{ inputs.cdk-dir }}
         run: npx -y cdk deploy --all --require-approval never
+
+      - name: Post-deploy health check
+        if: ${{ inputs.stack-name != '' }}
+        run: |
+          echo "Health check: verifying stack ${{ inputs.stack-name }}..."
+
+          STATUS=$(aws cloudformation describe-stacks \
+            --stack-name "${{ inputs.stack-name }}" \
+            --query 'Stacks[0].StackStatus' --output text)
+          if [[ "$STATUS" != *"COMPLETE" ]] || [[ "$STATUS" == *"ROLLBACK"* ]]; then
+            echo "::error::Stack ${{ inputs.stack-name }} ended in $STATUS after deploy."
+            exit 1
+          fi
+          echo "Stack status: $STATUS"
+
+          echo "Stack outputs:"
+          aws cloudformation describe-stacks \
+            --stack-name "${{ inputs.stack-name }}" \
+            --query 'Stacks[0].Outputs[*].[OutputKey,OutputValue]' --output table
+
+          # Run project-specific health check if it exists
+          if [[ -f scripts/health-check.sh ]]; then
+            echo "Running project health check..."
+            bash scripts/health-check.sh "${{ inputs.stack-name }}" "${{ inputs.region }}"
+          fi
+
+          echo "Health check passed."
diff --git a/.github/workflows/cd-sam.yaml b/.github/workflows/cd-sam.yaml
index e5a53d3..0d8f69f 100644
--- a/.github/workflows/cd-sam.yaml
+++ b/.github/workflows/cd-sam.yaml
@@ -53,6 +53,29 @@ jobs:
           role-to-assume: ${{ secrets.deploy-role-arn }}
           aws-region: ${{ inputs.region }}
 
+      - name: Pre-flight checks
+        run: |
+          echo "Pre-flight: checking stack ${{ inputs.stack-name }}..."
+          STATUS=$(aws cloudformation describe-stacks \
+            --stack-name "${{ inputs.stack-name }}" \
+            --query 'Stacks[0].StackStatus' --output text 2>/dev/null || echo "NOT_FOUND")
+          case "$STATUS" in
+            *ROLLBACK_COMPLETE|*FAILED)
+              echo "::error::Stack ${{ inputs.stack-name }} is in $STATUS — manual intervention required."
+              exit 1
+              ;;
+            *IN_PROGRESS)
+              echo "::error::Stack ${{ inputs.stack-name }} has an operation in progress ($STATUS) — wait for it to complete."
+              exit 1
+              ;;
+            NOT_FOUND)
+              echo "Pre-flight: stack not found — will be created on first deploy."
+              ;;
+            *)
+              echo "Pre-flight: stack status is $STATUS — OK to deploy."
+              ;;
+          esac
+
       - name: SAM build
         run: sam build --template ${{ inputs.sam-template }}
 
@@ -71,3 +94,29 @@ jobs:
             --no-fail-on-empty-changeset \
             --role-arn ${{ inputs.cfn-role-arn }} \
             $PARAMS
+
+      - name: Post-deploy health check
+        run: |
+          echo "Health check: verifying stack ${{ inputs.stack-name }}..."
+
+          STATUS=$(aws cloudformation describe-stacks \
+            --stack-name "${{ inputs.stack-name }}" \
+            --query 'Stacks[0].StackStatus' --output text)
+          if [[ "$STATUS" != *"COMPLETE" ]] || [[ "$STATUS" == *"ROLLBACK"* ]]; then
+            echo "::error::Stack ${{ inputs.stack-name }} ended in $STATUS after deploy."
+            exit 1
+          fi
+          echo "Stack status: $STATUS"
+
+          echo "Stack outputs:"
+          aws cloudformation describe-stacks \
+            --stack-name "${{ inputs.stack-name }}" \
+            --query 'Stacks[0].Outputs[*].[OutputKey,OutputValue]' --output table
+
+          # Run project-specific health check if it exists
+          if [[ -f scripts/health-check.sh ]]; then
+            echo "Running project health check..."
+            bash scripts/health-check.sh "${{ inputs.stack-name }}" "${{ inputs.region }}"
+          fi
+
+          echo "Health check passed."
diff --git a/.github/workflows/ci-python-sam.yaml b/.github/workflows/ci-python-sam.yaml
index eae99be..d64faf7 100644
--- a/.github/workflows/ci-python-sam.yaml
+++ b/.github/workflows/ci-python-sam.yaml
@@ -34,7 +34,11 @@ on:
       node-version:
         description: "Node.js version for CDK CLI"
         type: string
-        default: "22"
+        default: "24"
+      run-conventions-check:
+        description: "Run lightweight conventions audit"
+        type: boolean
+        default: true
 
 jobs:
   ci:
@@ -81,6 +85,52 @@ jobs:
         working-directory: ${{ inputs.cdk-dir }}
         run: npx -y cdk synth --quiet
 
+      - name: Conventions check
+        if: ${{ inputs.run-conventions-check }}
+        run: |
+          errors=0
+          warn() { echo "::warning::$1"; }
+          fail() { echo "::error::$1"; errors=$((errors + 1)); }
+
+          # README must exist
+          if [[ ! -f README.md ]]; then
+            fail "Missing README.md"
+          fi
+
+          # .gitignore must cover .env
+          if [[ -f .gitignore ]]; then
+            if ! grep -qE '^\\.env$|^\\.env\\b' .gitignore; then
+              fail ".gitignore does not include .env"
+            fi
+          else
+            fail "Missing .gitignore"
+          fi
+
+          # SAM: check template for non-arm64 and missing log retention
+          TEMPLATE="${{ inputs.sam-template }}"
+          if [[ -f "$TEMPLATE" ]]; then
+            if grep -qi 'x86_64' "$TEMPLATE" 2>/dev/null; then
+              fail "SAM template: Lambda using x86_64 instead of arm64"
+            fi
+            if grep -qi 'AWS::Serverless::Function' "$TEMPLATE" 2>/dev/null; then
+              if ! grep -qi 'RetentionInDays\|AWS::Logs::LogGroup' "$TEMPLATE" 2>/dev/null; then
+                warn "SAM template: Lambda found but no explicit log retention"
+              fi
+            fi
+            # Check for secrets in environment variables
+            if grep -qiE '(API_KEY|SECRET|TOKEN|PASSWORD|WEBHOOK)' "$TEMPLATE" 2>/dev/null; then
+              if grep -A5 'Environment:' "$TEMPLATE" | grep -qiE '(API_KEY|SECRET|TOKEN|PASSWORD|WEBHOOK)' 2>/dev/null; then
+                fail "SAM template: possible secret in Lambda environment variables — use Secrets Manager"
+              fi
+            fi
+          fi
+
+          if [[ $errors -gt 0 ]]; then
+            echo "Conventions check failed with $errors error(s)."
+            exit 1
+          fi
+          echo "Conventions check passed."
+
       - name: Setup SAM CLI
         if: ${{ inputs.run-sam-validate }}
         uses: aws-actions/setup-sam@v2
diff --git a/.github/workflows/ci-typescript-cdk.yaml b/.github/workflows/ci-typescript-cdk.yaml
index 9467b47..7048973 100644
--- a/.github/workflows/ci-typescript-cdk.yaml
+++ b/.github/workflows/ci-typescript-cdk.yaml
@@ -6,7 +6,7 @@ on:
       node-version:
         description: "Node.js version to use"
         type: string
-        default: "22"
+        default: "24"
       run-typecheck:
         description: "Run tsc --noEmit"
         type: boolean
@@ -27,6 +27,10 @@ on:
         description: "Enable QEMU for cross-platform Docker builds (arm64 on x86 runners)"
         type: boolean
         default: false
+      run-conventions-check:
+        description: "Run lightweight conventions audit"
+        type: boolean
+        default: true
       run-sam-validate:
         description: "Run sam validate --lint (for Node.js SAM repos)"
         type: boolean
@@ -39,7 +43,7 @@ on:
 jobs:
   ci:
     runs-on: ubuntu-latest
-    timeout-minutes: 10
+    timeout-minutes: 30
     steps:
       - uses: actions/checkout@v4
 
@@ -70,6 +74,52 @@ jobs:
         if: ${{ inputs.run-cdk-synth }}
         run: npx cdk synth --quiet
 
+      - name: Conventions check
+        if: ${{ inputs.run-conventions-check }}
+        run: |
+          errors=0
+          warn() { echo "::warning::$1"; }
+          fail() { echo "::error::$1"; errors=$((errors + 1)); }
+
+          # README must exist
+          if [[ ! -f README.md ]]; then
+            fail "Missing README.md"
+          fi
+
+          # .gitignore must cover .env
+          if [[ -f .gitignore ]]; then
+            if ! grep -qE '^\\.env$|^\\.env\\b' .gitignore; then
+              fail ".gitignore does not include .env"
+            fi
+          else
+            fail "Missing .gitignore"
+          fi
+
+          # CDK: check synth output for non-arm64 Lambdas and missing log retention
+          if [[ -d cdk.out ]]; then
+            for tmpl in cdk.out/*.template.json; do
+              [[ -f "$tmpl" ]] || continue
+
+              # Check for x86_64 Lambdas
+              if grep -q '"Architectures".*x86_64' "$tmpl" 2>/dev/null; then
+                fail "$(basename "$tmpl"): Lambda using x86_64 instead of arm64"
+              fi
+
+              # Check Lambdas exist but no log retention set
+              if grep -q '"AWS::Lambda::Function"' "$tmpl" 2>/dev/null; then
+                if ! grep -q '"AWS::Logs::LogGroup"' "$tmpl" 2>/dev/null; then
+                  warn "$(basename "$tmpl"): Lambda found but no explicit LogGroup with retention"
+                fi
+              fi
+            done
+          fi
+
+          if [[ $errors -gt 0 ]]; then
+            echo "Conventions check failed with $errors error(s)."
+            exit 1
+          fi
+          echo "Conventions check passed."
+
       - name: Setup SAM CLI
         if: ${{ inputs.run-sam-validate }}
         uses: aws-actions/setup-sam@v2