[Artifact Forest 5/9] Recover screenplay structure from PDF and unstructured text

[szmyty]

Parent: #421
Depends on: #423
Coordinates with: #424, #425

Outcome

Support an explicitly lossy, review-required path from screenplay-shaped PDF or text into a recoverable screenplay representation and then into Fountain/other script derivatives.

Pipeline

PDF
 ├─ text-bearing → deterministic text/layout extraction
 └─ image-only   → bounded OCR fallback
                     ↓
              screenplay recovery
                     ↓
          renderflow.screenplay/v1
             ├─ Fountain
             ├─ FDX
             ├─ FadeIn
             └─ OSF

Provider candidates

• Poppler pdftotext / equivalent local deterministic extractor.
• Existing Tesseract provider for image-only pages.
• Optional reviewed AI transform only when deterministic recovery is insufficient and policy explicitly allows it.

Requirements

• Detect whether PDF has usable text before OCR.
• Preserve page boundaries and extraction evidence.
• Define deterministic screenplay heuristics for scene headings, character cues, dialogue, parentheticals, and action.
• Emit confidence/ambiguity diagnostics per recovered element.
• Never silently treat OCR or heuristic output as the original screenplay.
• AI recovery must be optional, separately evidenced, and never required for deterministic extraction.
• Feed the recovered screenplay through [Artifact Forest 2/9] Define canonical screenplay artifacts and capability truth #423 validation before downstream conversions.
• Do not regenerate PDF by default when PDF was the source; source-format suppression from [Artifact Forest 1/9] Define cycle-safe exhaustive derivative planning #422 applies.

Acceptance criteria

• Text PDF → reviewed screenplay candidate works on a synthetic fixture.
• Image-only PDF takes the OCR path or reports provider unavailability.
• Recovery evidence names extraction method and confidence/ambiguity.
• Fountain/FDX/etc. derivatives are marked as recovered/lossy lineage.
• Source PDF is unchanged and not regenerated by an exhaustive forest unless explicitly requested.
• Malformed/encrypted/unsupported PDFs produce typed outcomes.
• Optional AI cannot upgrade confidence or approval without explicit evidence/review.

Non-goals

Claiming exact Final Draft reconstruction or visual-layout preservation from arbitrary PDFs.