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 scripts/fetch_page.py
3. Parse HTML via scripts/parse_html.py
4. Optionally fetch CWV via scripts/pagespeed_check.py (use --skip-cwv to skip)
5. Hash HTML body and schema content (SHA-256)
6. Store snapshot in SQLite

Execution:

bash
claude-seo run drift_baseline.py <url>
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:

bash
claude-seo run drift_compare.py <url>
claude-seo run drift_compare.py <url> --baseline-id 5
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:

bash
claude-seo run drift_report.py <comparison_json_file> --output drift-report.html

Command: history

Shows all baselines and comparisons for a URL.

Execution:

bash
claude-seo run drift_history.py <url>
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 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?