# SPRINT_4400 SUMMARY: Delta Verdicts & Reachability Attestations

## Program Overview

| Field | Value |
|-------|-------|
| **Program ID** | 4400 |
| **Theme** | Attestable Change Control: Delta Verdicts & Reachability Proofs |
| **Priority** | P2 (Medium) |
| **Total Effort** | ~4 weeks |
| **Advisory Source** | 19-Dec-2025 - Stella Ops candidate features mapped to moat strength |

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## Strategic Context

This program extends the attestation infrastructure to cover:
1. **Smart-Diff semantic delta** — Changes in exploitable surface as signed artifacts
2. **Reachability proofs** — Call-path subgraphs as portable evidence

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## Sprint Breakdown

| Sprint ID | Title | Effort | Moat |
|-----------|-------|--------|------|
| 4400_0001_0001 | Signed Delta Verdict Attestation | 2 weeks | 4 |
| 4400_0001_0002 | Reachability Subgraph Attestation | 2 weeks | 4 |

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## Dependencies

- **Requires**: SPRINT_4300_0001_0001 (OCI Verdict Push)
- **Requires**: MaterialRiskChangeDetector (exists)
- **Requires**: PathWitnessBuilder (exists)

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## Outcomes

1. Delta verdicts become attestable change-control artifacts
2. Reachability analysis produces portable proof subgraphs
3. Both can be pushed to OCI registries as referrers

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**Sprint Series Status:** TODO

**Created:** 2025-12-22