Horizon diagnoses an existing ready PDF without rewriting it. Its private validator checks supported archival/accessibility profiles and returns a bounded report tied to the original hash. This is a separate pipeline from antivirus verification, document readiness and dispatch approval.
Three different questions
| Question | Responsible boundary |
|---|---|
| Can this exact PDF be used safely under the application’s checks? | Document scanning and isolated PDF validation |
| Which supported machine-checkable conformance rules pass or fail? | Horizon diagnostic profile and private validator |
| Is the document usable and appropriate for its real audience? | Human review, including reading order, alternatives and interaction |
A quarantined document cannot bypass its security gate by requesting a diagnostic. A favorable automated report is not a certification, human review or permission to send. Reports retain explicit manual-review requirements.
A bounded, immutable report
Web, REST and MCP share the validation service. The request chooses a supported profile and stable idempotency key; the tenant and original bytes come from authenticated access, not caller-supplied ownership fields.
Before execution and again before publishing a report, the server checks current session/connection authority, scopes, resource access, exact bytes and entitlement. The response must match the expected hash/profile, pinned validator and complete rule totals. Time, stream/chunk size and retained findings are bounded. Replaying an already handled idempotent request does not start a second engine run.
The private validator operates on a temporary exact original without runtime network access. Reports keep allowed rule identifiers and counters, not arbitrary PDF text, snippets, raw engine output or customer content in logs.
Entitlement does not grant document access
The optional plan uses explicit recurring administrator-browser consent, atomic credit accounting and a bounded attempt allowance. Assistants and ordinary members cannot create billing consent. Running diagnostics still requires the caller’s current document permission and applicable OAuth scope.
Engine errors are not passing conformance results and can consume an allowed attempt. Missing required bindings or scanner readiness must fail closed; enough credit alone does not enable the service. Existing report-read policy is separate from the ability to start a new diagnostic.
Corrections create new documents
A report may explain findings, but the pipeline performs no silent remediation. A corrected PDF must be imported or generated as a new immutable version, scanned and diagnosed as appropriate. An old report or dispatch approval does not transfer to its changed bytes.
For the underlying file lifecycle, read documents and exact bytes. For client authorization and capability checks, read REST and MCP. The feature atlas records the implementation and activation boundaries without claiming that a plan is currently open for every account.