seo-crawlability (M1)

Crawl access is the precondition for every other search signal: if Googlebot/Bingbot can't fetch the page and its assets, nothing else ranks. This module covers general-purpose crawl access only. AI-specific bot directives (GPTBot, Claude-SearchBot, etc.) live in seo-ai-crawlers (M14) and AI discovery files (llms.txt, agents.md, UCP) in seo-ai-discovery (M21); see references/ai-crawlers.md for that boundary.

Inputs

Work from the PageSnapshot named in your dispatch envelope: read parsed from <run_dir>/pages/<slug>.json plus status_chain and headers, and the parsed robots file in <run_dir>/site/robots.json (syntax, groups, Googlebot/Bingbot verdicts for the audited URL, Sitemap: lines); Grep pages/<slug>.html for verbatim evidence. Deterministic findings already emitted by audit.mjs are listed in <run_dir>/findings.deterministic.json — do not re-emit those ids; add model-judged findings only. If invoked directly with a URL/path and no snapshot exists, first run node "${CLAUDE_PLUGIN_ROOT}/scripts/snapshot.mjs" <target> --out "${CLAUDE_PLUGIN_DATA}/runs" and use the printed snapshot path.

Audits

Working from the PageSnapshot (parsed_rendered when render.used is not none, else parsed) plus site/robots.json:

1. Reachability: /robots.txt returns 200 (a 404 means "allow all" but is worth flagging; a 5xx can suspend crawling).
2. Syntax: each line is a valid directive (User-agent, Disallow, Allow, Sitemap, Crawl-delay); flag unknown tokens, missing User-agent group headers, and BOM/encoding issues.
3. Asset blocking: any Disallow that blocks CSS/JS, fonts, or /wp-includes/-style paths — this breaks rendering and is a leading cause of "page looks broken to Google" (cross-check with M-render).
4. Content blocking: Disallow rules that hide important indexable paths from Googlebot/Bingbot.
5. Crawl-delay sanity: a large Crawl-delay (or one applied to the global group) can starve crawl budget; note that Googlebot ignores Crawl-delay but Bingbot honors it.
6. Sitemap directive: presence of at least one absolute Sitemap: URL.
7. Overall access: resolve the effective ruleset for Googlebot and Bingbot against the audited URL — does it end up allowed?

Fixes

Generated edits are a diff for fix, mapped to the schema fixable field:

• AUTO: remove an accidental Disallow of CSS/JS or a key content path (additive un-block, verifiable); add a missing absolute Sitemap: line; repair malformed syntax (e.g. Dissallow typo, missing colon, group with no User-agent header).
• PROPOSED: tightening Crawl-delay or restructuring User-agent groups — drafted, requires per-item accept because intent may be deliberate.
• ADVISORY: changing what is intentionally disallowed (private/staging paths) — never written by the tool. Never fabricate a sitemap URL or path: if the canonical sitemap location is unknown, emit a clearly-marked TODO placeholder for the user to fill, or ask.

Verification

• node "${CLAUDE_PLUGIN_ROOT}/scripts/parse-robots-sitemap.mjs" --url <final_url> --path <audited path> — fetches and parses /robots.txt, resolves the effective allow/deny for Googlebot/Bingbot against the audited path (not the root), and checks for the Sitemap: directive (method robots_parse). Use --robots <robots_url> or --file <path> for an offline robots file.
• When /robots.txt cannot be fetched (network/auth/edge block) the status is needs_api, never a false pass.

Findings

Emit findings per schema/finding.schema.json; axis search. Severity policy: 5 is reserved for catastrophic, eligibility-killing facts at site/template scope; 4 major · 3 moderate · 2 minor · 1 cosmetic · 0 informational — and only an established severity-5 fail in an active category can cap a score (references/scoring-model.md).

• M1.robots.blocks_googlebot — the effective ruleset disallows the audited URL for Googlebot (fail, severity 5, fixable: proposed, confidence established). Site-wide, this is the single most destructive robots defect there is; it stays at 5.
• M1.robots.blocks_css_js — a Disallow matches CSS/JS the rendered page loads, degrading how Google renders it (fail, severity 4, fixable: auto, confidence established).
• M1.robots.unreachable — /robots.txt returns 5xx, which suspends crawling until it recovers (fail, severity 5 at site scope, fixable: advisory, confidence established).
• M1.robots.syntax_error — malformed directive, missing User-agent group header, or a BOM (warn, severity 3, fixable: auto, confidence established).
• M1.sitemap.missing_directive — no Sitemap: line in robots.txt (warn, severity 2, fixable: auto, confidence directional — sitemaps are also discovered from Search Console and /sitemap.xml, so a missing directive is a convenience gap, not an access failure).
• M1.crawl_delay.excessive — a large Crawl-delay in the global group that starves honoring crawlers (warn, severity 2, fixable: proposed, confidence directional). Platform-conditional ids. This module also emits 6 ids that fire only when profile.json names the platform (shopify, wordpress, nextjs). They are indexed in references/routing.md § Platform-conditional finding ids and specified in references/platforms/<id>.md §10.

Each finding: evidence.observed quotes the offending robots.txt line (or the resolved verdict) verbatim; verification.reproduce is the runnable command above; expected_impact is banded + confidence-tagged (no naked %).

Honesty

• robots.txt controls crawling, not indexing: a Disallow-ed page can still be indexed (URL-only) from external links. To keep a page out of the index use a noindex meta tag and do not also Disallow it, or the crawler can never see the noindex.
• A missing or 404 robots.txt is not a defect — it means "crawl everything". Don't report it as a fail; flag it as informational. A 5xx is different: it is treated as a full disallow while it lasts.
• Crawl-delay is ignored by Googlebot; recommending it as a Google crawl lever is a myth — scope the advice to Bingbot and other honoring agents.
• Resolve every verdict against the audited path, not /. A site that allows the root and disallows /blog/ is a common shape, and a root-only check reports the wrong answer.
• On a preview or staging host a blanket Disallow: / is the expected configuration; the scorer suppresses M1.robots.* caps when --environment preview|staging|local is set (see references/scoring-model.md).