# SEO Drift Comparison Rules 17 rules across 3 severity levels. Each rule compares a specific SEO element between the stored baseline and the current page state. --- ## CRITICAL (Immediate Action Required) These changes typically cause measurable traffic loss within days. ### Rule 1: Schema/JSON-LD Completely Removed - **Compare**: Baseline `schema` array has items, current is empty - **Threshold**: Any schema present before, none now - **Action**: Restore structured data immediately. Rich results will be lost within hours. - **Cross-ref**: `/seo schema ` ### Rule 2: Canonical URL Changed - **Compare**: Baseline `canonical` vs current `canonical` - **Threshold**: Different non-null values (after normalization) - **Action**: Verify the new canonical is intentional. Incorrect canonicals redirect ranking signals to wrong page. - **Cross-ref**: `/seo technical ` ### Rule 3: Canonical URL Removed - **Compare**: Baseline `canonical` was set, current is `null` - **Threshold**: Had value, now missing - **Action**: Restore canonical tag. Google will guess, often incorrectly for pages with query parameters. - **Cross-ref**: `/seo technical ` ### Rule 4: Noindex Directive Added - **Compare**: Baseline `meta_robots` did not contain "noindex", current does - **Threshold**: "noindex" substring now present (case-insensitive) - **Action**: If unintentional, remove immediately. Page will be dropped from index within days. - **Cross-ref**: `/seo technical ` ### Rule 5: H1 Tag Removed Entirely - **Compare**: Baseline `h1` had entries, current is empty - **Threshold**: One or more H1s before, zero now - **Action**: Restore H1 heading. Primary page topic signal for search engines. - **Cross-ref**: `/seo content ` ### Rule 6: H1 Text Changed Significantly - **Compare**: First H1 in baseline vs first H1 in current, SequenceMatcher ratio - **Threshold**: Similarity ratio < 0.5 (>50% different) - **Action**: Verify the H1 change aligns with target keyword strategy. - **Cross-ref**: `/seo content ` ### Rule 7: Title Tag Removed Entirely - **Compare**: Baseline `title` was set, current is `null` or empty - **Threshold**: Had value, now missing - **Action**: Restore title tag immediately. Google will auto-generate one, often poorly. - **Cross-ref**: `/seo page ` ### Rule 8: HTTP Status Code Changed to Error - **Compare**: Baseline `status_code` was 2xx, current is 4xx or 5xx - **Threshold**: Status code class changed from success to client/server error - **Action**: Investigate server error or missing page. Rankings will drop within days. - **Cross-ref**: `/seo technical ` --- ## WARNING (Investigate Within 1 Week) These changes may impact rankings or CTR but are sometimes intentional. ### Rule 9: Title Text Changed - **Compare**: Baseline `title` vs current `title` (trimmed) - **Threshold**: Strings differ (case-sensitive, whitespace-normalized) - **Action**: Verify new title includes target keywords. Monitor CTR in GSC over 2 weeks. - **Cross-ref**: `/seo page ` ### Rule 10: Meta Description Changed - **Compare**: Baseline `meta_description` vs current `meta_description` - **Threshold**: Strings differ (trimmed) - **Action**: Verify new description includes call-to-action and target keywords. Monitor CTR. - **Cross-ref**: `/seo page ` ### Rule 11: Core Web Vitals Metric Regressed >20% - **Compare**: Each CWV metric p75 value (LCP, INP, CLS) baseline vs current - **Threshold**: Current value is >20% worse than baseline (higher for LCP/INP, higher for CLS) - **Action**: Investigate performance regression. Check recent code changes or third-party scripts. - **Cross-ref**: `/seo technical ` ### Rule 12: CWV Performance Score Dropped 10+ Points - **Compare**: Lighthouse performance score baseline vs current - **Threshold**: Drop of 10 or more points (e.g., 85 to 74) - **Action**: Run full PageSpeed analysis to identify new bottlenecks. - **Cross-ref**: `/seo google psi ` ### Rule 13: OG Tags Removed - **Compare**: Baseline `open_graph` had entries, current is empty - **Threshold**: One or more OG tags before, none now - **Action**: Restore OG tags. Social sharing will show generic/missing previews. - **Cross-ref**: `/seo page ` ### Rule 14: Schema/JSON-LD Content Modified - **Compare**: Baseline `schema_hash` vs current `schema_hash` - **Threshold**: Hash differs AND schema still exists (removal is Rule 1) - **Action**: Validate modified schema. Check for type changes, removed properties, or new validation errors. - **Cross-ref**: `/seo schema ` --- ## INFO (Awareness Only) These are tracked for completeness. Often positive or neutral changes. ### Rule 15: New Schema/JSON-LD Added - **Compare**: Baseline `schema` was empty, current has items - **Threshold**: No schema before, schema now present - **Action**: Positive change. Validate the new schema with `/seo schema `. - **Cross-ref**: `/seo schema ` ### Rule 16: H2 Structure Changed - **Compare**: Baseline `h2` array vs current `h2` array - **Threshold**: Different number of H2s, or different H2 text values - **Action**: Review heading hierarchy. Ensure content sections still align with target topics. - **Cross-ref**: `/seo content ` ### Rule 17: Content Hash Changed - **Compare**: Baseline `html_hash` vs current `html_hash` - **Threshold**: Hash differs (catch-all for any body content change) - **Action**: General content change detected. Review if no other rules triggered to understand what changed. - **Cross-ref**: `/seo page `