seo-drift

SEO Drift Monitor (April 2026)

Shared Data Cache

Step 0 -- Check shared data cache:

Before gathering, check .seo-cache/ for reusable context from related SEO skills.

Reference: ../seo/references/shared-data-cache.md for schemas and dependency map.

Check these cache files when present:

• .seo-cache/site-meta.json for domain, business type, industry, and crawl context
• .seo-cache/audit-scores.json for prior full-audit priorities
• .seo-cache/pages/{url-slug}/page-analysis.json for page-level context when a URL is provided

• If found: parse and use clearly valid fields (note "Using cached [X] from [date]")
• If missing, corrupt, or irrelevant: continue with fresh evidence
• If the user says "refresh" or "re-run": ignore cache reads and overwrite on write

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

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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 |

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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 |

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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 |

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Storage

All data is stored locally in SQLite:

~/.cache/codex-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.

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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:

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.

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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:

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

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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.

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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 |

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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. |

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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

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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?

Write to shared data cache

After completing all work, write a concise JSON summary to .seo-cache/ when the workflow produced durable findings.

Use the schemas and naming rules in ../seo/references/shared-data-cache.md; include at least cache_type, analyzed_at, source URL/domain, key findings, issues, recommendations, and tool limitations. Add .seo-cache/ to .gitignore if it is missing.