PrismCAD is a local-first, zero-trust AI assistant designed specifically as a plug-in for AutoCAD 2025 and 2026. Unlike generic cloud-based AI tools that operate as unpredictable black boxes with direct access to production files, PrismCAD bridges natural-language intent with strict deterministic execution. It utilizes a decoupled architecture where a local Python planning sidecar communicates via loopback (127.0.0.1) with a high-performance C# AutoCAD kernel, ensuring that proprietary drawing files never leave the local workstation. Core features include: Dual RAG Engine & SQLite Hot Cache (ProjectPrism): Automatically indexes drawing entities and spatial relationships locally with a 500ms debouncer for instant contextual resolution. Space Tagging & Room Extraction: Understands semantic spaces and architectural room labels (such as specific rooms or tags) to anchor commands accurately. Mandatory Human Approval Gate: Translates prompts into structured execution plans, rendering a visual WPF preview so users can review and approve every step before it touches the database. Cryptographic Execution Guardrails: Canonically hashes approved plans (SHA-256) and authorizes transactions using an Ed25519 cryptographic key protected by Windows DPAPI, re-validating live drawing fingerprints right before commit to guarantee atomicity and prevent file corruption.

PrismCad

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