Conflict Checker

Cross-discipline design contradiction detector for construction drawing sets. Built for architects to back-check a set (Arch / Struct / Mech / Elec / Plumb / FP / …) before it goes out to a GC for bid. It flags information that disagrees between disciplines — e.g. the RCP ceiling height vs the mechanical duct elevation, a door schedule count vs the floor plan, a column that lands in a corridor.

This is not the IronBid scope-ownership conflict checker (who-owns-what for bidding). That stays in IronBid; this tool is a separate, design-QA pipeline.

How it works (hybrid extract-then-compare)

PDF  ->  page images  ->  per-sheet grounded facts  ->  cluster by location  ->  reason  ->  report
        Stage 0           Stage 1 (vision)             Stage 2 (no LLM)        Stage 3      Stage 4

1. Stage 0 pdf_processor — PDF pages to base64 JPEGs (100 DPI, 2400px cap).
2. Stage 1 extractor — one vision call per sheet extracts discrete, grounded assertions (each carries verbatim source_text and a location_key). A grounding guard drops any assertion whose number isn't in its own source text.
3. Stage 2 clusterer — deterministic: groups assertions that refer to the same grid / room / tag across ≥2 disciplines (or a schedule-vs-plan within one). This keeps Stage 3 calls small and few.
4. Stage 3 conflict_checker — one reasoning call per cluster (with the relevant sheet images) decides whether the disciplines genuinely contradict, and classifies it.
5. Stage 4 report — conflicts.json + a readable report.md.

The model is google/gemini-2.5-pro via OpenRouter (configurable). All prompt tuning lives in backend/prompts.py — the system prompts, the attribute vocabulary, and the conflict taxonomy.

Setup

python3 -m venv .venv && . .venv/bin/activate
pip install -r requirements.txt          # needs system poppler-utils for pdf2image
cp backend/.env.example backend/.env      # then set AI_API_KEY to your OpenRouter key

Run

CLI (the fast tuning loop — also dumps assertions.json / clusters.json for inspection):

python cli/run_check.py samples/your_set.pdf --out out/your_set
# -> out/your_set/report.md  +  conflicts.json

Web UI (upload + view):

uvicorn backend.main:app --reload   # open http://127.0.0.1:8000

Conflict categories

dimensional_disagreement, elevation_disagreement, location_mismatch, missing_element, schedule_vs_plan_mismatch, tag_or_reference_inconsistency, spatial_clash, note_or_spec_contradiction.

Tuning

• Edit prompts/vocab/taxonomy in backend/prompts.py.
• Inspect out/<set>/assertions.json to see what Stage 1 extracted, and out/<set>/clusters.json to see what got compared. Most false negatives are a clustering/extraction miss; most false positives are a Stage-3 prompt issue.
• Build a golden set: hand-verify conflicts.json for a known set and diff future runs.

Known limitations (v1)

• A location appearing in only one discipline never forms a cluster, so pure "missing element" gaps aren't caught deterministically (Stage 3 still catches missing counterparts when the location is co-located).
• Stage 3 currently sends full pages, not crops. If accuracy/cost needs it, add crop-by-grid later.