Skip to content

Inputs, Regions, and Coordinates

Status: Current shared contract

Authority: Current contract and Detection input implementation

Last reviewed: 2026-08-14

Question

How do Drawing Lab inputs keep one page coordinate system across stages?

Short answer

Detection inputs are separate review regions. They are not independent coordinate systems. Every result keeps page coordinates.

Rules

  1. A review region points back to the same page.
  2. A crop or lens may limit what the reviewer sees.
  3. A crop or lens must not invent a private coordinate space for stored results.
  4. Later assembly may split or merge regions only with a membership ledger.
  5. Content outside a working rectangle must not silently disappear from accounting.

Why this matters

Earlier region experiments failed usefulness gates. The lab still retained the page-coordinate doctrine. Stable page coordinates let Table Detection, Dimension Detection, and sheet assembly compare results without hidden transforms.

Working area caution

The working-area detector remains an acceptance concern, not a trusted preprocessing fact. A long title-block divider can satisfy the old frame rule and exclude the title block. See Boundary, Wand, and RGB Deviation.

Open Questions

  • Which region membership ledger becomes the durable Detected Sheet contract?

Sources

  • Accepted decision: DL-010
  • Current contract: table-dimension-detection-architecture.md (2026-08-12)
  • Strategy freeze and working-area evaluation updates under Phase 4C1C and Phase 4C1D