SEO Drift Monitor (April 2026)

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

Commands

Command

Purpose

/seo drift baseline

Capture current SEO state as a "known good" snapshot

/seo drift compare

Compare current page state to stored baseline

/seo drift history

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: Validate URL (SSRF protection via google_auth.validate_url() ) Fetch page via scripts/fetch_page.py Parse HTML via scripts/parse_html.py Optionally fetch CWV via scripts/pagespeed_check.py (use --skip-cwv to skip) Hash HTML body and schema content (SHA-256) Store snapshot in SQLite Execution: python scripts/drift_baseline.py < url

python scripts/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: Validate URL Load most recent baseline from SQLite (or specific --baseline-id ) Fetch and parse current page state Run all 17 comparison rules Classify findings by severity Store comparison result Output JSON diff report Execution: python scripts/drift_compare.py < url

python scripts/drift_compare.py < url

--baseline-id 5 python scripts/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: python scripts/drift_report.py < comparison_json_file

--output drift-report.html Command: history Shows all baselines and comparisons for a URL. Execution: python scripts/drift_history.py < url

python scripts/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 for full validation CWV regression Run /seo technical for performance audit Title or meta description changed Run /seo page for content analysis Canonical changed or removed Run /seo technical for indexability check Noindex added Run /seo technical for crawlability audit H1/heading structure changed Run /seo content for E-E-A-T review OG tags removed Run /seo page for social sharing analysis Status code changed to error Run /seo technical 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 scripts/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?