Support non-standard per-user-agent robots directives via an extensible 'other' field

Many teams that manage SEO and site infrastructure—estimated across roughly 2,000,000 web-native businesses—struggle to express non-standard, per-user-agent directives today because robots metadata and robots.txt conventions are rigid and most frameworks only expose a narrow set of parameters. This problem is most acute for international publishers, vertical search integrations, and product teams managing localized or partner crawlers, where lack of per-agent controls forces error-prone workarounds and brittle deployment processes. You could build a small-spec plus implementation: an extensible "other" field for per-user-agent robots directives, accompanied by a registry of known vendor directives, SDKs and first-class integrations for modern frameworks (Next.js, Astro, etc.), CI-friendly validation hooks, and a lightweight SaaS dashboard for policy management and rollout. Open-source the spec and client libs to accelerate adoption while monetizing with enterprise features—policy auditing, change history, and team governance—targeting an ACV around $3k to match the market assumptions. The timing is favorable: the addressable market is roughly $6.0B (2,000,000 sites × $3k ACV), frameworks are centralizing metadata which creates a single integration point, and demand is rising from international and vertical crawlers plus teams that want SEO changes to be code-driven and testable; competition is currently low and revenue potential is reasonable (78/100). Differentiation will come from being both a pragmatic spec and the easiest-to-integrate developer experience, but realistic challenges include achieving critical mass for the registry, persuading framework maintainers to adopt or ship integrations, and proving value to conservative enterprise procurement teams.