Changelog

All notable changes to the AI Visibility Definition are documented here. The current version is 1.9.0.

This project follows Semantic Versioning and the Keep a Changelog format. Subscribe to the Atom feed for version updates.

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1.9.0 — 11 May 2026

Phase 6 of the spec standardisation work. Adds the long-term / forward-looking layer: a public roadmap, formal rules for extensions, internationalisation and accessibility guidance, the Discovery: directive in robots-ai.txt, a formal media-type stance, and an expanded integrity / signing roadmap. The Discovery: directive is the only normative addition to publisher behaviour; all other additions are forward-looking documentation.

Added

• Roadmap. Theme-pegged forward plan with status flags (Active, Next, Future, On hold). Intentionally not version-pegged.
• Extensions. Normative rules for experimental x--prefixed files, extension fields inside core JSON, and the six-step promotion path from experimental to core.
• Internationalisation & Accessibility. Multi-language publication, locale-tagged identity fields, RTL languages, non-Latin scripts, and accessibility of llms.html.
• The Discovery: directive in the robots-ai.txt specification. Publishers MAY advertise AI Discovery Files present on the same host. Solves the cold-start problem for consumers that do not probe root-level paths blindly.
• Formal media-type stance at HTTP behaviour section 10. Reuse existing text/plain, text/markdown, text/html, and application/json rather than introducing bespoke types.
• Expanded file integrity and signing section at security and privacy section 6. Four candidate signing mechanisms, six cross-cutting concerns, and interim guidance for publishers and consumers while signing remains On hold for a future MAJOR release.

Changed

• All 10 AI Discovery File specifications bumped MINOR. Eight specs 1.6.0 to 1.7.0; two (faq-ai-txt, developer-ai-txt) 1.7.0 to 1.8.0.
• All 3 guides bumped to 1.6.0.
• Master definition bumped to 1.9.0.
• Registry data file bumped to 1.5.0.

Phase reference

This release completes Phase 6 of the spec standardisation work documented in docs/plans/2026-05-10-spec-standardisation-implementation.md. Phases 1 through 6 are now complete; the original ChatGPT review brief is fulfilled.

1.8.0 — 11 May 2026

Phase 5 of the spec standardisation work. Adds the positioning layer: where the AI Discovery Files specification sits in the wider standards landscape, who has implemented it, how it stays backwards-compatible with the llmstxt.org convention, and how the host-scoping rule applies across domains and subdomains.

Added

• Relationship to Other Standards. Positions the specification against ten neighbours: llmstxt.org, IETF AI Preferences, robots.txt and RFC 9309, Schema.org, Common Crawl and AI crawler user agents, W3C AI Use Disclosure, BCP 14, JSON Schema 2020-12, Semantic Versioning 2.0.0, and other web-discovery conventions.
• Implementations. Public record of conformant implementations, modelled on the IETF implementation-report pattern. Lists the four implementation roles (Publisher, Validator, Registry, Consumer) and the five current implementations (WordPress plugin, AI Visibility Checker, AI Visible Directory, manual templates, Service Pack).
• llmstxt.org backward-compatibility statement in the llms.txt specification. An llmstxt.org-conformant llms.txt file is a valid llms.txt at the Essential conformance class under this specification. Publishers who follow the llmstxt.org convention need no migration to claim Essential conformance.
• Multi-domain and subdomain scoping rule in the llms.txt and identity.json specifications. Files are host-scoped per RFC 3986; cross-host identity MUST be asserted via mutual sameAs declarations.
• Standards Framework section on the specifications hub and the spec sidebar. Surfaces the Phase 2-5 framework pages (conformance, conventions, registry, versioning, governance, security and privacy, HTTP behaviour, processing model, consumer guidance, test vectors, related standards, implementations) as a dedicated block.

Changed

• All 10 AI Discovery File specifications bumped MINOR. Eight specs 1.5.0 to 1.6.0; two (faq-ai-txt, developer-ai-txt) 1.6.0 to 1.7.0.
• All 3 guides bumped to 1.5.0.
• Master definition bumped to 1.8.0.
• Registry data file bumped to 1.4.0.

Phase reference

This release completes Phase 5 of the spec standardisation work documented in docs/plans/2026-05-10-spec-standardisation-implementation.md.

1.7.0 — 11 May 2026

Phase 4 of the spec standardisation work. Adds the implementer-facing depth layer: a formal processing model for conformant consumers, guidance on what AI systems should do with publisher signals, a canonical test-vector framing, and reference-implementation framing on the AI Visibility Checker. No normative requirements changed.

Added

• Processing Model. Algorithmic specification covering the seven stages a conformant consumer applies: discover, fetch, validate, resolve identity, resolve permissions, detect contradictions, emit. Given the same input, two conformant implementations must produce equivalent output.
• AI Consumer Guidance. What AI systems should do with AI Discovery Files. Covers training-time use, retrieval-time use, citation conventions, conversational behaviour, contradiction handling, and defensive posture.
• Test Vectors framing. Documents where the canonical test suite lives (the ai-discovery-files spec repository), how each test case is structured (input files, expected.json, readme), the requirement-ID convention, and how validator authors apply the suite.
• Reference-implementation framing on the AI Visibility Checker. The checker hero now formally states it is the reference implementation of the AI Discovery Files specification.

Changed

• All 10 AI Discovery File specifications bumped MINOR. Eight specs 1.4.0 to 1.5.0; two (faq-ai-txt, developer-ai-txt) 1.5.0 to 1.6.0.
• All 3 guides bumped to 1.4.0.
• Master definition bumped to 1.7.0.
• Registry data file bumped to 1.3.0.

Phase reference

This release completes Phase 4 of the spec standardisation work documented in docs/plans/2026-05-10-spec-standardisation-implementation.md.

1.6.0 — 11 May 2026

Phase 3 of the spec standardisation work. Adds the process, policy, and security layer that surrounds every specification: versioning and deprecation policy, governance and editorial process, security and privacy considerations, and HTTP behaviour. No normative requirements changed; every addition is documentation surfacing rules and contracts that the rest of the specification family already assumed.

Added

• Versioning and Deprecation Policy. Single source for Semantic Versioning 2.0.0 commitments (MAJOR, MINOR, PATCH), the deprecation timeline (minimum 12-month window between Deprecated and Retired), and the specification lifecycle from Draft through Stable to Deprecated to Retired.
• Governance and Editorial Process. Documents the maintainer, the five-status proposal lifecycle (Proposed, Accepted, Published, Stable, Deprecated), the editorial process from capture to publication, working principles, and the contribution path through the project GitHub repository.
• Security and Privacy Considerations. Cross-cutting guidance: trust model (HTTPS host as anchor, no signing yet), content-injection patterns publishers should avoid, GDPR considerations for personal data in publisher files, the access-control boundary (AI Discovery Files are advisory, not enforcement), logging and fingerprinting implications, and the forthcoming file-integrity primitives.
• HTTP Behaviour. The HTTP-protocol-level contract every AI Discovery File specification assumes: HTTPS expected, status code expectations, redirect handling with a 5-hop maximum, soft-404 detection, query-string treatment, content negotiation expectations, cache headers, rate-limit guidance, and CORS.

Changed

• All 10 AI Discovery File specifications bumped MINOR. Eight specs (llms-txt, llm-txt, llms-html, ai-txt, ai-json, identity-json, brand-txt, robots-ai-txt) 1.3.0 to 1.4.0; two (faq-ai-txt, developer-ai-txt) 1.4.0 to 1.5.0. New versionHistory[] entry on every spec PHP page, JSON twin, and YAML twin.
• All 3 guides (quick-start, interoperability, validation) bumped MINOR to 1.3.0 with matching versionHistory[] entries.
• Master definition bumped to 1.6.0 as the umbrella release version.
• Registry data file bumped to 1.2.0 to reflect Phase 3 spec versions in files[].version.
• Specification Conventions page: the placeholder "forthcoming versioning policy page" note replaced with a link to the now-published versioning page. References list updated with links to all four new Phase 3 pages.

Spec affected

• ADF-001 through ADF-010 (all bumped)
• AV-001 through AV-006 wording unchanged

Phase reference

This release completes Phase 3 of the spec standardisation work documented in docs/plans/2026-05-10-spec-standardisation-implementation.md.

1.5.0 — 11 May 2026

Phase 2 of the spec standardisation work. Adds the conformance regime and the machine-readable infrastructure the rest of the standardisation depends on. All items shipped to the live site across batches between 2026-05-10 and 2026-05-11 as additive changes; this release is the coordinated bump that updates every spec and guide data file in lockstep.

Added

• Conformance specification. Formally defines the three conformance classes (Essential, Recommended, Complete), publisher conformance criteria, validator conformance criteria, and the distinction between self-declared and Directory-verified conformance. Every ADF spec page now carries a Conformance section listing the classes that include the file as anchored badges.
• Specification Registry at /specifications/registry.json. Machine-readable single source of truth listing all 10 AI Discovery Files with paths, media types, paired files, redirect targets, precedence rules, schema URLs, conformance-class membership, and current versions. Validators, plugins, and downstream tooling SHOULD load this at runtime rather than hard-coding the file list.
• Spec meta-schema at /specifications/spec-meta.schema.json. JSON Schema 2020-12 describing the shape of every *-specification.json data file.
• Validator-output schema at /specifications/validator-output.schema.json. Standard output format any conformant validator emits, so different validators can produce equivalent results for the same input. The AI Visibility Checker is the reference implementation.
• Versioned JSON Schema URLs at /specifications/ai-json/v1/ai-json.schema.json and /specifications/identity-json/v1/identity-json.schema.json. Permanent URLs alongside the existing unversioned "latest" aliases. Publishers can now pin their $schema field to a URL that will never change shape. See Schema URL versioning.
• Optional BCP 47 language declaration. Every AI Discovery File MAY declare its natural language using a BCP 47 tag. Lang: header for text files; language property for JSON files; existing <html lang> attribute for llms.html. See Language declaration in publisher files.
• Audit script extensions. Seven new Phase 2 checks covering registry shape, registry-versus-versions.php sync, registry paths on disk, spec-meta validation of every *-specification.json, validator-output schema compilation, versioned-schema $id consistency, and BCP 47 language tag validity.

Changed

• All 10 AI Discovery File specifications bumped MINOR. Eight specs (llms-txt, llm-txt, llms-html, ai-txt, ai-json, identity-json, brand-txt, robots-ai-txt) 1.2.0 to 1.3.0; two (faq-ai-txt, developer-ai-txt) 1.3.0 to 1.4.0. New versionHistory[] entry on every spec PHP page, JSON twin, and YAML twin.
• All 3 guides (quick-start, interoperability, validation) bumped MINOR to 1.2.0 with matching versionHistory[] entries.
• Master definition bumped to 1.5.0 as the umbrella release version.
• Registry data file bumped to 1.1.0 to reflect Phase 2 spec versions in files[].version.
• Canonical examples at root: /ai.json and /identity.json now reference the versioned schema URL (/v1/) and demonstrate the optional language field. /llms.txt demonstrates the Lang: en-GB header.

Fixed

• /checker/templates/identity.json: corrected a pre-existing bug where the template still referenced the old 365i.co.uk/ai-visibility-definition/... URL from before the project moved to its own domain. Now references the v1 URL on ai-visibility.org.uk.

Spec affected

• ADF-001 through ADF-010 (all bumped)
• AV-001 through AV-006 wording unchanged

Phase reference

This release completes Phase 2 of the spec standardisation work documented in docs/plans/2026-05-10-spec-standardisation-implementation.md.

1.4.0 — 10 May 2026

Phase 1 of the spec standardisation work — moves the AI Discovery Files specification from "useful published convention" to "credible community specification" by adopting the formal positioning, RFC 2119 keyword discipline, document statuses, conventions/licensing reference pages, and a coordinated release cadence. No normative requirements changed in this release; all changes are additive or stylistic normalisation.

Added

• Positioning statement — Published verbatim on the directory homepage, the specifications hub, and the definition page. Frames AI Discovery Files as an open, versioned community specification working towards recognised implementation-standard status.
• /licensing/ page — Single source for the project's licensing and trademark stance: CC BY 4.0 for specification text and examples, MIT for JSON Schemas, "AI Discovery Files" as descriptive (non-trademarked) phrase free for accurate reference, AI Visibility Directory verification badges as restricted assets.
• /specifications/conventions/ page — Single source for editorial and structural conventions used across every AI Discovery File specification. Cites RFC 2119 and RFC 8174 (BCP 14) for requirement keywords; documents the four document-status values (Draft, Stable, Deprecated, Retired); summarises Semantic Versioning 2.0.0 across PHP/JSON/YAML.
• "Status of This Document" block — Inserted on every spec page (10), every guide page (3), and the new conventions and licensing pages. All currently Stable. Each block links to /specifications/conventions/#status-values for the canonical status definitions.
• References section on every spec and guide page — Each spec now ends with a References section linking to the conventions page and the licensing page.
• /licensing/ link in the site footer — Between Terms and Support.
• Audit script (scripts/audit-spec-consistency.js) — Mechanical consistency checks across PHP/JSON/YAML data files: parse, version sync, dateModified vs versionDate, $schema discipline both ways, AV-xxx code consistency, JSON/YAML structural equivalence. Phase-gated; extends in each subsequent phase.

Changed

• All 10 AI Discovery File specifications — Bumped MINOR (llms-txt, llm-txt, llms-html, ai-txt, ai-json, identity-json, brand-txt, robots-ai-txt: 1.1.1 → 1.2.0; faq-ai-txt, developer-ai-txt: 1.2.0 → 1.3.0). Added Status block, applied RFC 2119 keyword normalisation in normative content, added References section.
• All 3 guides (quick-start, interoperability, validation) — Bumped MINOR to 1.1.0 with the same set of additions.
• Master definition — Bumped to 1.4.0 as the umbrella release version. Same additions applied to the definition page.
• RFC 2119 keyword normalisation — Across all 13 specs/guides plus their JSON/YAML twins, lowercase keywords inside normative content were normalised to uppercase per RFC 2119 / RFC 8174. Approximately 110 keyword occurrences uppercased across the codebase.

Fixed

• faq-ai-txt-specification.yaml — Three list items with unquoted colons that YAML interpreted as mapping syntax caused parse failure or silent semantic divergence with the JSON twin. Quoted; YAML now parses correctly and matches JSON shape.
• llm-txt-specification.yaml — Missing iis example key under implementation.methods[0].examples that exists in the JSON twin. Added.

Spec affected

• ADF-001 through ADF-010 (all)
• AV-001 through AV-006 wording unchanged

1.3.3 — 13 February 2026

Added

• AI Visibility Directory CTA — Registration guidance added to all specification pages, guide pages, and content pages promoting the AI Visibility Directory with two-tier listing comparison (Basic and Full)
• Version history entries (v1.1.1) added to all 10 AI Discovery File specification pages
• Version history entries added to Quick Start (v1.0.2), Interoperability (v1.0.1), and Validation (v1.0.1) guides
• Changelog link added to Specifications navigation dropdown

Changed

• "Last Modified" date on definition page is now dynamic (uses file modification timestamp instead of hardcoded date)
• Specification versions bumped from 1.1.0 to 1.1.1

1.3.2 — 16 January 2026

Added

• Implementation Guides — Three new guide pages to support specification adoption:
  • Quick Start Guide — Tiered implementation path with Essential (2 files), Recommended (6 files), and Complete (10 files) tiers
  • Interoperability Guide — Conflict resolution rules and precedence hierarchy for when AI Discovery Files contain contradictory information
  • Validation Framework — Standardised test prompts and scoring methodology to verify AI systems correctly interpret AI Discovery Files
• Guides section in specification sidebar navigation
• Implementation Guides section on specifications hub page with callout for newcomers
• Precedence rules and cross-references added to all 10 specification pages linking to Interoperability Guide

1.3.1 — 12 January 2026

Changed

• Site Restructure — Converted from static HTML to PHP-based architecture with external CSS, shared includes, dynamic schema generation, specification sidebar, and client-side search
• Dynamic dateModified using file modification timestamps
• ISO 8601 datetime format with timezone for Google Rich Results compliance

Fixed

• DateTime format validation errors in Google Rich Results Test

1.3.0 — 12 January 2026

Added

• AI Discovery File Specifications — 10 individual specification pages for each core AI Discovery File format: llms.txt, llm.txt, llms.html, ai.txt, ai.json, identity.json, brand.txt, faq-ai.txt, developer-ai.txt, robots-ai.txt
• Machine-readable specification files (JSON and YAML) for each format
• JSON Schema files for ai.json and identity.json validation
• Canonical example files using fictional business "Horizon Strategic Consulting"

1.2.0 — 12 January 2026

Added

• ai.json added to core AI Discovery Files list — machine-parseable AI interaction guidance in JSON format

1.1.0 — 12 January 2026

Added

• Frequently Asked Questions — Six questions addressing common clarifications about AI Visibility
• FAQPage JSON-LD structured data
• FAQ entries in machine-readable JSON and YAML formats

1.0.0 — 10 January 2026

Added

• Initial publication of canonical definitions
• AV-001: AI Visibility — the degree to which a website can be discovered, interpreted, and cited by AI systems
• AV-002: AI Visibility Checking — technical verification of AI-facing infrastructure
• AV-003: AI Discovery Files — machine-readable files for AI communication
• AV-004: AI Visibility Tracking — ongoing measurement of AI-generated mentions
• AV-005: AI Visibility Monitoring — real-time observation of AI behaviour
• AV-006: AI Retrieval Testing — prompt-based observation of AI responses
• Taxonomy establishing hierarchical relationships between terms
• Reference implementation link to 365i AI Website Visibility Checker
• HTML, JSON, and YAML format availability
• Schema.org DefinedTerm structured data