> ## Documentation Index
> Fetch the complete documentation index at: https://docs.horizonmanaged.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Bid engine

> Construction and low-voltage bidding — AI drawing takeoff, addendum handling, scope narratives, and deterministic cost math

The Bid Engine is NEXOS CORE's construction, low-voltage, and electrical bidding
tool — it replaces an Excel cost workbook with a server-side calculation engine
and AI-assisted takeoff. Create a bid sheet, upload the spec documents and
drawings, and NEXOS CORE reads the drawings with Claude Vision to count devices,
generates line items grouped by trade, applies addendums, writes a scope
narrative, and runs a pre-submission audit — all while computing hard cost,
margins, tax, commission, and grand total deterministically.

Open it at `/bids`.

## When to use it

* Bid a construction / low-voltage / electrical job (cameras, cabling, access
  control, fire alarm).
* Take off devices from plan sets without hand-counting.
* Re-scope existing line items against issued addendums.
* Get a pre-submission sanity check before you send a bid.
* Generate a contractor-readable scope-of-work narrative from the source docs.

## Cost math

Costing is deterministic: material + tax + subs + equipment + labor + burden =
**hard cost**; hard cost × (overhead + profit + contingency); + commission; +
customer sales tax; + permits and bond = **grand total** — with profit per
man-day, margin %, and an optional manual bid-price override.

## Drawing takeoff (Vision)

Point the engine at a bid's drawings and it runs Claude Vision (via the
[Drawings](/drawing) module) to count low-voltage devices, then generates
trade-grouped line items from the takeoff — drawings are authoritative for
quantities. Takeoff is scoped to the trades the bid actually covers.

<Note>
  The same device can appear on several sheets (floor plan, RCP, riser). The
  **Vision Findings** audit surfaces per-sheet counts and duplicate tags, and
  **Dedupe by tag** keeps the highest-quantity sheet — review it, since it's a
  heuristic that can drop a legitimate sheet.
</Note>

## Addendums

Upload an addendum and each page is mirrored in; a sheet whose number matches a
base drawing automatically supersedes the older one. For line-item impact, AI
produces a **reviewable diff** (partial-scope aware — e.g. "terminations by
others" trims labor rather than deleting the cable), which you Apply or Dismiss
per change.

## Reconciliation, scope summary, and audit

* **Reconcile** compares spec-required vs. drawing-observed quantities, row by row.
* **Scope summary** generates an editable SoW narrative (overview, in/out scope,
  assumptions, risks, quantities).
* **Pre-submission audit** flags red/yellow/green findings (phantom OFCI hardware,
  double-counted labor); **red findings block** moving a draft to submitted.

## Good to know

* The AI steps (takeoff, reconcile, addendum diff, scope summary) require your
  tenant's Claude API key and carry a per-drawing cost.
* Confidence scores on generated items are AI-supplied estimates — verify before
  you submit.