save checkpoint: save features

docs/features/checked/scanner/base-image-detection-and-recommendations.md

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+# Base Image Detection and Recommendations
+
+## Module
+Scanner
+
+## Status
+VERIFIED
+
+## Description
+Base image detection via layer diffID fingerprinting with PostgreSQL-backed fingerprint storage and deterministic in-memory matching. The detector now supports exact and fuzzy matching, ranked recommendations, and bulk recommendation queries for multiple image references.
+
+## Implementation Details
+- **Core detection contract**:
+  - `src/Scanner/__Libraries/StellaOps.Scanner.Manifest/Resolution/IBaseImageDetector.cs`
+    - `DetectBaseImageAsync` (single-layer lookup)
+    - `GetRecommendationsAsync` (ranked exact/fuzzy recommendations)
+    - `GetRecommendationsBulkAsync` (bulk recommendations)
+- **Detector implementation**:
+  - `src/Scanner/__Libraries/StellaOps.Scanner.Manifest/Resolution/BaseImageDetector.cs`
+    - PostgreSQL-backed fingerprint persistence and load
+    - deterministic in-memory index
+    - fuzzy fallback by nearest layer index + lexical tie-break
+- **Recommendation scoring engine**:
+  - `src/Scanner/__Libraries/StellaOps.Scanner.Manifest/Resolution/BaseImageMatchEngine.cs`
+    - deterministic exact/fuzzy scoring with confidence and rationale
+- **Layer resolution + reuse integration**:
+  - `src/Scanner/__Libraries/StellaOps.Scanner.Manifest/Resolution/ILayerDigestResolver.cs`
+  - `src/Scanner/__Libraries/StellaOps.Scanner.Manifest/Resolution/LayerDigestResolver.cs`
+  - `src/Scanner/__Libraries/StellaOps.Scanner.Manifest/Resolution/LayerProvenance.cs`
+  - `src/Scanner/__Libraries/StellaOps.Scanner.Manifest/Reuse/ILayerReuseDetector.cs`
+  - `src/Scanner/__Libraries/StellaOps.Scanner.Manifest/Reuse/LayerReuseDetector.cs`
+- **DI registration**:
+  - `src/Scanner/__Libraries/StellaOps.Scanner.Manifest/ManifestServiceCollectionExtensions.cs`
+- **Behavioral tests**:
+  - `src/Scanner/__Tests/StellaOps.Scanner.Core.Tests/BaseImageRecommendationTests.cs`
+
+## E2E Test Plan
+- [x] Scan an image built on a known base image and verify exact base image attribution is returned.
+- [x] Verify exact layer prefix match identifies the correct base image with confidence `1.0`.
+- [x] Verify fuzzy matching returns ranked recommendations when base layers are partially modified.
+- [x] Verify bulk recommendations return deterministic per-image results for multiple image references.
+- [x] Verify non-overlapping layers return no recommendations (negative path).
+
+## Verification
+- Run ID: `run-001`
+- Date (UTC): 2026-02-12
+- Tier 0: Source files and symbols present (`tier0-source-check.json`).
+- Tier 1: `StellaOps.Scanner.Manifest` + `StellaOps.Scanner.Core.Tests` build passed; focused recommendation tests passed (`tier1-build-check.json`, `tier1-tests-base-image.log`).
+- Tier 2: Behavioral integration checks passed via targeted class run (`tier2-e2e-check.json`).