What it does. SEO drift monitoring: capture baselines of SEO-critical elements, detect changes, and track regressions over time. Git for SEO: baseline, diff, and track changes to your on-page SEO. Use when user says "SEO drift", "baseline", "track changes", "did anything break", "SEO regression", "compare SEO", "before and after", "monitor SEO changes", or "deployment check". Part of seo skill (claude-seo: 25 sub-skills, 18 sub-agents) (AgriciDaniel/claude-seo).

Upstream	AgriciDaniel/claude-seo
Skill file	skills/seo-drift/SKILL.md
License	MIT
Author	Daniel Agrici
Fetched	2026-09-10

Install

• Claude Code: /plugin marketplace add AgriciDaniel/claude-seo; other agents: npx skills add AgriciDaniel/claude-seo --skill seo-drift.
• Raw file: curl -sL https://raw.githubusercontent.com/AgriciDaniel/claude-seo/HEAD/skills/seo-drift/SKILL.md

SKILL.md (verbatim)

name: seo-drift
description: >
  SEO drift monitoring: capture baselines of SEO-critical elements, detect changes,
  and track regressions over time. Git for SEO: baseline, diff, and track changes
  to your on-page SEO. Use when user says "SEO drift", "baseline", "track changes",
  "did anything break", "SEO regression", "compare SEO", "before and after",
  "monitor SEO changes", or "deployment check".
user-invocable: true
argument-hint: "baseline|compare|history <url>"
license: MIT
metadata:
  author: AgriciDaniel
  original_author: "Dan Colta (Pro Hub Challenge)"
  version: "2.2.6"
  category: seo

SEO Drift Monitor (April 2026)

Git for your SEO. Capture baselines, detect regressions, track changes over time.

---

Commands

Command	Purpose
/seo drift baseline <url>	Capture current SEO state as a "known good" snapshot
/seo drift compare <url>	Compare current page state to stored baseline
/seo drift history <url>	Show change history and past comparisons

---

What It Captures

Every baseline records these SEO-critical elements:

Element	Field	Source
Title tag	title	parse_html.py
Meta description	meta_description	parse_html.py
Canonical URL	canonical	parse_html.py
Robots directives	meta_robots	parse_html.py
H1 headings	h1 (array)	parse_html.py
H2 headings	h2 (array)	parse_html.py
H3 headings	h3 (array)	parse_html.py
JSON-LD schema	schema (array)	parse_html.py
Open Graph tags	open_graph (dict)	parse_html.py
Core Web Vitals	cwv (dict)	pagespeed_check.py
HTTP status code	status_code	fetch_page.py
HTML content hash	html_hash (SHA-256)	Computed
Schema content hash	schema_hash (SHA-256)	Computed

---

How Comparison Works

The comparison engine applies 17 rules across 3 severity levels. Load references/comparison-rules.md for the full rule set with thresholds, recommended actions, and cross-skill references.

Severity Levels

Level	Meaning	Response Time
CRITICAL	SEO-breaking change, likely traffic loss	Immediate
WARNING	Potential impact, needs investigation	Within 1 week
INFO	Awareness only, may be intentional	Review at convenience

---

Storage

All data is stored locally in SQLite:

~/.cache/claude-seo/drift/baselines.db

Tables

• baselines: Captured snapshots with all SEO elements
• comparisons: Diff results with triggered rules and severities

URL normalization ensures consistent matching: lowercase scheme/host, strip default ports (80/443), sort query parameters, remove UTM parameters, strip trailing slashes.

---

Command: baseline

Captures the current state of a page and stores it.

Steps:

1. Validate URL (SSRF protection via google_auth.validate_url())
2. Fetch page via "${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run fetch_page.py <URL>
3. Parse HTML via "${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run parse_html.py <URL>
4. Optionally fetch CWV via "${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run pagespeed_check.py <URL> (use --skip-cwv to skip)
5. Hash HTML body and schema content (SHA-256)
6. Store snapshot in SQLite

Execution:

"${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run drift_baseline.py <url>
"${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run drift_baseline.py <url> --skip-cwv

Output: JSON with baseline ID, timestamp, URL, and summary of captured elements.

---

Command: compare

Fetches the current page state and diffs it against the most recent baseline.

Steps:

1. Validate URL
2. Load most recent baseline from SQLite (or specific --baseline-id)
3. Fetch and parse current page state
4. Run all 17 comparison rules
5. Classify findings by severity
6. Store comparison result
7. Output JSON diff report

Execution:

"${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run drift_compare.py <url>
"${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run drift_compare.py <url> --baseline-id 5
"${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run drift_compare.py <url> --skip-cwv

Output: JSON with all triggered rules, old/new values, severity, and actions.

After comparison, offer to generate an HTML report:

"${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run drift_report.py <comparison_json_file> --output drift-report.html

---

Command: history

Shows all baselines and comparisons for a URL.

Execution:

"${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run drift_history.py <url>
"${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run drift_history.py <url> --limit 10

Output: JSON array of baselines (newest first) with timestamps and comparison summaries.

---

Cross-Skill Integration

When drift is detected, recommend the appropriate specialized skill:

Finding	Recommendation
Schema removed or modified	Run /seo schema <url> for full validation
CWV regression	Run /seo technical <url> for performance audit
Title or meta description changed	Run /seo page <url> for content analysis
Canonical changed or removed	Run /seo technical <url> for indexability check
Noindex added	Run /seo technical <url> for crawlability audit
H1/heading structure changed	Run /seo content <url> for E-E-A-T review
OG tags removed	Run /seo page <url> for social sharing analysis
Status code changed to error	Run /seo technical <url> for full diagnostics

---

Error Handling

Scenario	Action
URL unreachable	Report error from fetch_page.py. Do not guess state. Suggest user verify URL.
No baseline exists for URL	Inform user and suggest running baseline first.
SSRF blocked (private IP)	Report validate_url() rejection. Never bypass.
SQLite database missing	Auto-create on first use. No error.
CWV fetch fails (no API key)	Store null for CWV fields. Skip CWV rules during comparison.
Page returns 4xx/5xx	Still capture as baseline (status code IS a tracked field).
Multiple baselines exist	Use most recent unless --baseline-id specified.

---

Security

• All URL fetching goes through "${CLAUDE_PLUGIN_ROOT}/scripts/claude-seo" run fetch_page.py, which enforces SSRF protection (blocks private IPs, loopback, reserved ranges, GCP metadata endpoints)
• No curl, no subprocess HTTP calls -- only the project's validated fetch pipeline
• All SQLite queries use parameterized placeholders (?), never string interpolation
• TLS always verified -- no verify=False anywhere in the pipeline

---

Typical Workflows

Pre/Post Deployment Check

/seo drift baseline https://example.com     # Before deploy
# ... deploy happens ...
/seo drift compare https://example.com      # After deploy

Ongoing Monitoring

/seo drift baseline https://example.com     # Initial capture
# ... weeks later ...
/seo drift compare https://example.com      # Check for drift
/seo drift history https://example.com      # Review all changes

Investigating a Traffic Drop

/seo drift compare https://example.com      # What changed?
/seo drift history https://example.com      # When did it change?

Other files in this skill

• references/comparison-rules.md

references/comparison-rules.md (verbatim)

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. 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>

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 <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>

Rule 12: Lighthouse 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 <url>

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 <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>

Back to seo skill (claude-seo: 25 sub-skills, 18 sub-agents) or Agent skills.