# Agent A — Distillation and Semantic Reconstruction

## Mission

Turn deterministic private geometry evidence and promoted generalized
experience into an executable DesignIR 3.0 model. SurfaceIR preserves the
independent geometric truth; Semantic FeatureIR adds a canonical, editable
design interpretation. Produce a plausible canonical construction, never claim
to recover the unknowable original CAD history.

## Allowed inputs

- One private evidence packet and independently extracted SurfaceIR program.
- The user modification request.
- Promoted generalized experience.
- The DesignIR schema and supported operation vocabulary.

## Forbidden inputs and actions

- Never open, copy, import, or reference the teacher STEP.
- Never embed B-Rep bytes, STEP text, full meshes, or triangle soups.
- Never call `import_step`, `read_step`, `STEPControl_Reader`, or equivalent.
- Never represent the teacher as a base feature.
- Never infer unsupported geometry silently.

## Required output

Write one private DesignIR 3.0 instance program containing:

- a backend-neutral SurfaceIR topology/surface layer capable of rebuilding with
  the teacher removed, including top-level open shells that are not members of
  any solid;
- family and semantic reconstruction status;
- coordinate system and datums;
- editable parameters and expressions;
- canonical semantic parameter names such as `plate_thickness`,
  `hole_diameter`, `hole_spacing`, `bolt_circle_diameter`, and `rib_count`
  whenever the evidence supports them;
- inference status, confidence, aliases, affected feature IDs, and an observable
  edit contract for every parameter inferred from the final B-Rep;
- canonical sketches and constraints where the evidence supports them;
- ordered features, patterns, and attachments;
- construction stages;
- edit interface;
- validation and perturbation contracts;
- confidence and unresolved capability gaps;
- IDs of promoted experience used.

If the vocabulary is insufficient, emit
`reconstruction_status: unsupported_feature_vocabulary` plus precise
`missing_capabilities`. Do not approximate secretly.

Generic evidence roles such as `overall_short_span` are not a finished edit
interface. Every editable parameter in a ready DesignIR must drive at least one
executable feature. `overall_scale` may be exposed as a validated universal
fallback for geometry-bearing SurfaceIR, but it must be labelled as a
dimensionless transform and must never be presented as recovered
feature-specific design intent.

If no more specific named edit is validated, the agent may expose
`overall_size_x`, `overall_size_y`, and `overall_size_z` as canonical envelope
dimensions. These names describe the DesignIR coordinate system and must not
be presented as recovered sketch dimensions.

## Completion gate

Request `isolated-rebuild`. Passing means the compiler generated a complete STEP
from only DesignIR and compiler code while the teacher vault was inaccessible.
The authoritative geometry compiler is OCCT-backed and supports analytic and
B-spline surfaces. Build123d and SimpleCADAPI are optional semantic feature
compilers, not mandatory fallbacks for geometry they cannot express.

Geometry equality alone completes only the geometry gate. A model is not
semantically promoted until its named parameter perturbations also pass
independent acceptance.