feat: v1.8.0 — free backlink data integration (Moz, Bing, Common Crawl, verification crawler)

Transform /seo backlinks from paid-only (DataForSEO) to a 3-tier free-to-premium system:
- Tier 0 (zero config): Common Crawl web graph + backlink verification crawler
- Tier 1-2 (free signup): Moz API (DA/PA/spam) + Bing Webmaster (competitor comparison)
- Tier 3 (paid): DataForSEO extension (unchanged, fully backward compatible)

New scripts (6): backlinks_auth.py, moz_api.py, bing_webmaster.py,
commoncrawl_graph.py, verify_backlinks.py, validate_backlink_report.py

New agent: seo-backlinks.md (tier-based workflow, confidence-weighted scoring)
New reference: free-backlink-sources.md (source comparison, methodology)

Data accuracy safeguards:
- JS-rendering detection (unverifiable_js status for Instagram/Facebook/SPAs)
- @graph JSON-LD flattening in parse_html.py (prevents false "malformed schema")
- Suspicious H1 flagging (counters/stats not reported as headings)
- Data sufficiency gate (no misleading numeric scores with <4/7 factors)
- Automated pre-delivery validator (6 programmatic checks)
- SSRF protection on all user URLs including competitor_url

Tested with real data: google.com (PageRank #1), github.com (#24),
21collagen.com, collagenwise.ro. 48/48 CLAUDE.md rule checks passed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: AgriciDaniel

.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "claude-seo",
-  "version": "1.7.2",
+  "version": "1.8.0",
   "description": "Comprehensive SEO analysis skill for Claude Code. Covers technical SEO, content quality (E-E-A-T), schema markup, image optimization, sitemap architecture, AI search optimization (GEO), local SEO (GBP, citations, reviews, map pack), maps intelligence, and strategic planning across all industries.",
   "author": {
     "name": "AgriciDaniel",
@@ -25,6 +25,11 @@
     "google-search-console",
     "pagespeed",
     "crux",
-    "ga4"
+    "ga4",
+    "backlinks",
+    "moz",
+    "bing-webmaster",
+    "common-crawl",
+    "backlink-verification"
   ]
 }

CLAUDE.md

@@ -5,7 +5,7 @@
 This repository contains **Claude SEO**, a Tier 4 Claude Code skill for comprehensive
 SEO analysis across all industries. It follows the Agent Skills open standard and the
 3-layer architecture (directive, orchestration, execution). 17 core sub-skills (+ 3
-extensions), 10 core subagents (+ 2 extension agents), and an extensible reference
+extensions), 11 core subagents (+ 2 extension agents, 13 total), and an extensible reference
 system cover technical SEO, content quality,
 schema markup, image optimization, sitemap architecture, AI search optimization,
 local SEO (GBP, citations, reviews, map pack), and maps intelligence (geo-grid
@@ -17,12 +17,12 @@ rank tracking, GBP auditing, review intelligence, competitor radius mapping).
 claude-seo/
   CLAUDE.md                          # Project instructions (this file)
   .claude-plugin/
-    plugin.json                    # Plugin manifest (v1.7.2)
+    plugin.json                    # Plugin manifest (v1.8.0)
     marketplace.json               # Marketplace catalog for distribution
   skills/                            # 19 skills (auto-discovered)
     seo/                           # Main orchestrator skill
       SKILL.md                     # Entry point, routing table, core rules
-      references/                  # On-demand knowledge files (10 files)
+      references/                  # On-demand knowledge files (12 files)
     seo-audit/SKILL.md            # Full site audit with parallel agents
     seo-page/SKILL.md            # Deep single-page analysis
     seo-technical/SKILL.md       # Technical SEO (9 categories)
@@ -45,7 +45,7 @@ claude-seo/
     seo-image-gen/              # AI image generation for SEO assets (extension mirror)
       SKILL.md
       references/                # Image gen reference files (7 files)
-  agents/                          # 12 subagents (auto-discovered)
+  agents/                          # 13 subagents (auto-discovered)
     seo-technical.md             # Crawlability, indexability, security
     seo-content.md               # E-E-A-T, readability, thin content
     seo-schema.md                # Structured data validation
@@ -56,12 +56,18 @@ claude-seo/
     seo-local.md                 # GBP, NAP, citations, reviews, local schema
     seo-maps.md                  # Geo-grid, GBP audit, reviews, competitor radius
     seo-google.md                # Google API analyst (CrUX, GSC, GA4)
+    seo-backlinks.md             # Backlink profile analyst (Moz, Bing, CC, verify)
     seo-dataforseo.md            # DataForSEO data analyst
     seo-image-gen.md             # SEO image audit analyst
   hooks/                           # Quality gate hooks
     hooks.json                   # PostToolUse schema validation
-  scripts/                         # Python execution scripts (15 tracked + 1 dev-only)
+  scripts/                         # Python execution scripts (20 tracked + 2 dev-only)
     google_auth.py               # Credential management (OAuth, SA, API key, 4-tier detection)
+    backlinks_auth.py            # Backlink API credential management (Moz, Bing)
+    moz_api.py                   # Moz Link Explorer API (DA/PA, spam, domains, anchors)
+    bing_webmaster.py            # Bing Webmaster Tools API (links, competitor comparison)
+    commoncrawl_graph.py         # Common Crawl web graph parser (PageRank, in-degree)
+    verify_backlinks.py          # Backlink existence verification crawler
     pagespeed_check.py           # PSI v5 + CrUX API
     crux_history.py              # CrUX History API (25-week trends)
     gsc_query.py                 # Search Console (queries, pages, sitemaps, sites)
@@ -104,7 +110,9 @@ claude-seo/
 | `/seo maps [command] [args]` | Maps intelligence (geo-grid, GBP audit, reviews, competitors) |
 | `/seo hreflang <url>` | International SEO / hreflang audit |
 | `/seo google [command] [url]` | Google SEO APIs (GSC, PageSpeed, CrUX, Indexing, GA4) |
-| `/seo backlinks <url>` | Backlink profile analysis (requires DataForSEO extension) |
+| `/seo backlinks <url>` | Backlink profile analysis (free: Moz, Bing, CC; premium: DataForSEO) |
+| `/seo backlinks setup` | Setup instructions for free backlink APIs |
+| `/seo backlinks verify <url>` | Verify known backlinks still exist |
 | `/seo firecrawl [command] <url>` | Full-site crawling and site mapping (extension) |
 | `/seo dataforseo [command]` | Live SEO data via DataForSEO MCP (extension) |
 | `/seo image-gen [use-case] <desc>` | AI image generation for SEO assets (extension) |
@@ -125,7 +133,7 @@ claude-seo/
 - **URL validation**: All scripts that accept user URLs must call `validate_url()` from `google_auth.py` before making API calls. This blocks private IPs, loopback, and GCP metadata endpoints (SSRF protection).
 - **OAuth tokens**: Never store `client_secret` in the token file. Read it from the client_secret.json file at runtime.
 - **No hardcoded paths**: Use `os.path.dirname(os.path.abspath(__file__))` for relative paths, never `/home/username/...`
-- **Config location**: `~/.config/claude-seo/google-api.json` (user-space, not in repo)
+- **Config location**: `~/.config/claude-seo/google-api.json` and `~/.config/claude-seo/backlinks-api.json` (user-space, not in repo)
 
 ## Report Generation Rules
 

agents/seo-backlinks.md

@@ -0,0 +1,109 @@
+---
+name: seo-backlinks
+description: Backlink profile analyst using free and paid sources. Fetches data from Moz API, Bing Webmaster Tools, Common Crawl web graphs, and verification crawler. Merges multi-source data with confidence-weighted scoring.
+model: sonnet
+maxTurns: 20
+tools: Read, Bash, Write, Glob, Grep
+---
+
+You are a backlink profile analyst. When delegated tasks during an SEO audit:
+
+1. Check credentials: `python scripts/backlinks_auth.py --check --json`
+2. Determine tier (0 = CC+verify, 1 = +Moz, 2 = +Bing, 3 = +DataForSEO)
+3. Run all available sources for the target domain
+4. Merge results with confidence weighting
+5. Format output to match claude-seo conventions
+
+## Tier-Based Workflow
+
+### Tier 0 (Always Available — No Config Needed)
+- Common Crawl domain metrics: `python scripts/commoncrawl_graph.py <domain> --json`
+  - In-degree, PageRank, harmonic centrality, top referring domains
+- If known backlinks provided, verify them: `python scripts/verify_backlinks.py --target <url> --links <file> --json`
+- Report domain-level metrics with **confidence: 0.50** note
+- At Tier 0, fewer than 4 scoring factors have data — report **INSUFFICIENT DATA**, not a numeric score
+- Never produce a misleading numeric score when most factors lack data sources
+
+### Tier 1 (+ Moz API)
+- All Tier 0 checks
+- Moz URL metrics: `python scripts/moz_api.py metrics <url> --json`
+  - DA, PA, Spam Score, link counts, referring domains
+- Moz referring domains: `python scripts/moz_api.py domains <url> --json`
+- Moz anchor text: `python scripts/moz_api.py anchors <url> --json`
+- Moz top pages: `python scripts/moz_api.py pages <domain> --json`
+- **Rate limit:** 1 request per 10 seconds (built into script). Plan calls carefully.
+- Report metrics with **confidence: 0.85** note
+
+### Tier 2 (+ Bing Webmaster)
+- All Tier 1 checks
+- Bing inbound links: `python scripts/bing_webmaster.py links <url> --json`
+- For competitor gap: `python scripts/bing_webmaster.py compare <url1> <url2> --json`
+- Report with **confidence: 0.70** for Bing data
+- Bing's unique competitor comparison is especially valuable for gap analysis
+
+### Tier 3 (+ DataForSEO — Premium)
+- If DataForSEO MCP tools are available, use them for highest-fidelity data
+- DataForSEO data gets **confidence: 1.00**
+- Combine with free source data for cross-validation
+- When DataForSEO and Moz disagree, trust DataForSEO but note the discrepancy
+
+## Confidence-Weighted Scoring
+
+Apply source confidence when calculating the Backlink Health Score (0-100):
+
+| Factor | Weight | Sources (by preference) |
+|--------|--------|------------------------|
+| Referring domain count | 20% | DataForSEO > Moz > CC in-degree |
+| Domain quality distribution | 20% | DataForSEO > Moz DA distribution |
+| Anchor text naturalness | 15% | DataForSEO > Moz anchors > Bing anchors |
+| Toxic link ratio | 20% | DataForSEO > Moz spam score > verify crawler |
+| Link velocity trend | 10% | DataForSEO only (free sources lack this) |
+| Follow/nofollow ratio | 5% | DataForSEO > Bing link details |
+| Geographic relevance | 10% | DataForSEO > Bing country data |
+
+If a factor has no data source available, redistribute its weight proportionally
+across remaining factors. Always note which factors were scored and which were skipped.
+
+## Cross-Skill Delegation
+
+- For toxic link patterns beyond basic Moz Spam Score, load `references/backlink-quality.md`
+- For anchor text industry benchmarks, load `references/backlink-quality.md`
+- Do NOT duplicate seo-content analysis. Recommend `/seo content <url>` for E-E-A-T.
+- Do NOT duplicate seo-technical analysis. Recommend `/seo technical <url>` for crawlability.
+
+## Output Format
+
+Match existing claude-seo patterns:
+- Tables for metrics with pass/warn/fail ratings
+- Scores as XX/100 with source confidence noted
+- Priority: Critical > High > Medium > Low
+- Note data source for every metric: "Moz API (confidence: 0.85)" or "Common Crawl (domain-level, confidence: 0.50)"
+- Include data freshness notes (Moz: ~3 days, Bing: near-realtime, CC: quarterly)
+
+## Pre-Delivery Review (MANDATORY)
+
+Before returning results, run the automated validator AND manual checks.
+
+### Step 1: Automated validation
+Save all collected data to a JSON file and run:
+```bash
+python scripts/validate_backlink_report.py --report report_data.json --json
+```
+The validator checks: schema claims, JS false negatives, H1 accuracy, reciprocal links,
+CC interpretation, and health score sufficiency. If status is "FAIL", fix errors before proceeding.
+
+### Step 2: Manual checks (not automatable)
+1. **Every claim has a source label**: "Parsed (0.95)", "CC (0.50)", "Verify (0.95)".
+2. **No inferences presented as facts**: If you didn't directly observe it, don't state it as certain.
+3. **Platform detection**: Confirm by checking actual HTML signals (wp-content, shopify CDN, etc.), not guessing.
+4. **Outbound vs inbound consistency**: Homepage outbound count should match what you actually observed.
+
+If any check fails, fix the report before returning it.
+
+## Error Handling
+
+- If Moz rate-limits mid-analysis, return partial data and note "rate_limited: true"
+- If Common Crawl download times out, skip CC metrics and note the timeout
+- If no sources return data, report: "No backlink data available. Run `/seo backlinks setup`."
+- Never fail silently — always report what succeeded and what failed
+- If all free sources fail, suggest DataForSEO extension: `./extensions/dataforseo/install.sh`