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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.
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. Eligible rich results (Product, Review, LocalBusiness, and similar supported types) can drop from SERPs quickly; retired types (FAQ, HowTo) should not be treated as rich-result losses.
- Cross-ref:
/seo schema <url>
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 <url>
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 <url>
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 <url>
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 <url>
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 <url>
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 <url>
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 <url>
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 <url>
- 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 <url>
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 <url>
- 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 <url>
- 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 <url>
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 <url>
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 <url>.
- Cross-ref:
/seo schema <url>
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 <url>
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 <url>