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:

• 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 <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?