Taggart
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Changelog

What shipped

Every milestone ends with the corpus regression green, an accessibility pass on the application itself, and an entry here — including what is still missing.

1.0.0 — First release: check engine, remediation and the RTL engine

· milestone M1–M5

The first public release. Everything below is shipping, not planned.

Check engine

  • The full Matterhorn Protocol 1.1 rule set — 31 checkpoints, every failure condition — mapped to PDF/UA-1 clauses and WCAG 2.1 AA success criteria in a single shared rule file that drives the engine, the reports and this website.
  • Every machine-checkable condition the object model can decide, plus heuristics for the human-judgement conditions where a signal genuinely exists.
  • Three validation profiles: PDF/UA-1, WCAG 2.1 Level AA and IS 5568.
  • Severity model: blocker for machine-checkable failures, warning where a heuristic says a human will reject it, manual for genuine judgement calls. Nothing is ever auto-passed.

Right-to-left engine

  • Visual-order detection for Hebrew and Arabic, by comparing the order glyphs are painted in against their positions on the page, corroborated by Hebrew final-letter morphology.
  • Logical-order repair through /ActualText, leaving the content stream untouched.
  • Per-run /Lang tagging, in both directions — Hebrew runs in an English document and English runs in a Hebrew one.
  • Right-to-left aware column and reading-order evaluation.

Remediation

  • Mechanical fixes applied in bulk with a diff and a single undo.
  • Semantic fixes — headings, lists, alt text, artifacting — proposed and held for approval rather than applied unattended.
  • Appearance gate: every remediated file is re-rendered against the original and compared page by page at structural similarity ≥ 0.999. A file that fails is discarded rather than returned. It measures 1.000000 across the test corpus.
  • Taggart refuses to write a PDF/UA conformance claim its own re-validation cannot confirm.

Reading-order editor

  • Numbered badges drawn on the rendered page from the real structure tree.
  • Selection linked between the tree and the page in both directions.
  • Alt plus arrow keys to reorder from the keyboard, with an undo stack that spans a batch.
  • A real ARIA tree with roving tabindex, because shipping an inaccessible accessibility tool would be indefensible.

Reports

  • Remediation report in PDF and JSON: findings, fixes, accepted items with justifications, remaining issues, every human decision with an actor and a timestamp, the tool version, and the SHA-256 of both files.
  • The PDF report is itself tagged, titled, language-tagged and sets DisplayDocTitle.

Known limits

  • Batch and folder processing, and the CLI for CI pipelines, are in the Pro tier but not yet in the web application.
  • Font-program internals (conditions 31-011 to 31-026) are reported from the object model; the checks that require parsing the embedded font binary are marked partial in the rule file and say so in the report.
  • No OCR. Taggart detects that a document needs it and points at ocrmypdf rather than building a worse one.
  • PDF/UA-2 is not yet a profile.