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 |
| Compare current page state to stored baseline |
| Show change history and past comparisons |
What It Captures
Every baseline records these SEO-critical elements:
| Element | Field | Source |
|---|
| Title tag | | |
| Meta description | | |
| Canonical URL | | |
| Robots directives | | |
| H1 headings | (array) | |
| H2 headings | (array) | |
| H3 headings | (array) | |
| JSON-LD schema | (array) | |
| Open Graph tags | (dict) | |
| Core Web Vitals | (dict) | |
| HTTP status code | | |
| HTML content hash | (SHA-256) | Computed |
| Schema content 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:
Captures the current state of a page and stores it.
Steps:
- Validate URL (SSRF protection via
google_auth.validate_url()
- Fetch page via
- Parse HTML via
- Optionally fetch CWV via
scripts/pagespeed_check.py
- Hash HTML body and schema content (SHA-256)
- Store snapshot in SQLite
Execution:
bash
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:
Fetches the current page state and diffs it against the most recent baseline.
Steps:
- Validate URL
- Load most recent baseline from SQLite (or specific )
- Fetch and parse current page state
- Run all 17 comparison rules
- Classify findings by severity
- Store comparison result
- Output JSON diff report
Execution:
bash
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:
bash
python scripts/drift_report.py <comparison_json_file> --output drift-report.html
Command:
Shows all baselines and comparisons for a URL.
Execution:
bash
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 for full validation |
| CWV regression | Run for performance audit |
| Title or meta description changed | Run for content analysis |
| Canonical changed or removed | Run for indexability check |
| Noindex added | Run for crawlability audit |
| H1/heading structure changed | Run for E-E-A-T review |
| OG tags removed | Run for social sharing analysis |
| Status code changed to error | Run for full diagnostics |
Error Handling
| Scenario | Action |
|---|
| URL unreachable | Report error from . Do not guess state. Suggest user verify URL. |
| No baseline exists for URL | Inform user and suggest running first. |
| SSRF blocked (private IP) | Report rejection. Never bypass. |
| SQLite database missing | Auto-create on first use. No error. |
| CWV fetch fails (no API key) | Store 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 specified. |
Security
- All URL fetching goes through 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 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?