# Boundary Atlas: Why SFT Is Sharp

These entries exist to prevent overclaiming.

SFT is universal **on COC**, not on the universe of all dynamical descriptions. When a context falls outside the cyclic observability class, the engine is required to return a boundary obstruction with evidence.

## Common boundary mechanisms

- **No cyclic subsystem or phase observable**
  - Code: `WOB-01-no-subsystem`
  - Meaning: there is nothing to certify, so a coverage claim is inapplicable.

- **Wrong target or baseline in the presence of coupling**
  - Code: `WOB-06-coupling-mismatch`
  - Meaning: the image is restricted to a coupled subtorus but the claim is made on the full torus.

- **Equivariance is not realized or not within tolerance**
  - Codes: `WOB-08-orbit-collapse`, `WOB-09-equivariance-defect`

- **Resonant locking collapses intended rank**
  - Code: `WOB-10-resonant-locking`

- **Disconnected evidence domain**
  - Code: `WOB-11-disconnected-slice`

- **Ill-posed inference for CST constraints**
  - Codes: `WOB-13-ambiguity`, `WOB-14-insufficient-excitation`, `WOB-15-resonance-masking`

## Where to see boundary artifacts

- Witness atlas obstructions: `engine/artifacts/WOB-ATLAS-*.json`
- Codebook: `engine/contracts/WOB_CODEBOOK.md`

