Here’s a crisp product idea you can drop straight into Stella Ops: a **VEX “proof spine”**—an interactive, signed chain that shows exactly *why* a vuln is **not exploitable**, end‑to‑end.

---

# What it is (plain speak)

* A **proof spine** is a linear (but zoomable) chain of facts: *vuln → package → reachable symbol → guarded path → runtime context → policy verdict*.
* Each segment is **cryptographically signed** (DSSE, in‑toto style) so users can audit who/what asserted it, with hashes for inputs/outputs.
* In the UI, the chain appears as **locked graph segments**. Users can expand a segment to see the evidence, but they can’t alter it without breaking the signature.

---

# Why it’s different

* **From “scanner says so” to “here’s the evidence.”** This leap is what Trivy/Snyk static readouts don’t fully deliver: deterministic reachability + proof‑linked UX.
* **Time‑to‑Evidence (TtE)** drops: the path from alert → proof is one click, reducing back‑and‑forth with security and auditors.
* **Replayable & sovereign:** works offline, and every step is reproducible in air‑gapped audits.

---

# Minimal UX spec (fast to ship)

1. **Evidence Rail (left side)**

   * Badges per segment: *SBOM*, *Match*, *Reachability*, *Guards*, *Runtime*, *Policy*.
   * Each badge shows status: ✅ verified, ⚠️ partial, ❌ missing, ⏳ pending.
2. **Chain Canvas (center)**

   * Segments render as locked pills connected by a line.
   * Clicking a pill opens an **Evidence Drawer** with:

     * Inputs (hashes, versions), Tool ID, Who signed (key ID), Signature, Timestamp.
     * “Reproduce” button → prefilled `stellaops scan --replay <manifest hash>`.
3. **Verdict Capsule (top‑right)**

   * Final VEX statement (e.g., `not_affected: guarded-by-feature-flag`) with signer, expiry, and policy that produced it.
4. **Audit Mode toggle**

   * Freezes the view, shows raw DSSE envelopes and canonical JSON of each step.

---

# Data model (lean)

* `ProofSegment`

  * `type`: `SBOM|Match|Reachability|Guard|Runtime|Policy`
  * `inputs`: array of `{name, hash, mediaType}`
  * `result`: JSON blob (canonicalized)
  * `attestation`: DSSE envelope
  * `tool_id`, `version`, `started_at`, `finished_at`
* `ProofSpine`

  * `vuln_id`, `artifact_id`, `segments[]`, `verdict`, `spine_hash`

---

# Deterministic pipeline (dev notes)

1. **SBOM lock** → hash the SBOM slice relevant to the package.
2. **Vuln match** → store matcher inputs (CPE/PURL rules) and result.
3. **Reachability pass** → static callgraph diff with symbol list; record *exact* rule set and graph hash.
4. **Guard analysis** → record predicates (feature flags, config gates) and satisfiability result.
5. **Runtime sampling (optional)** → link eBPF trace or app telemetry digest.
6. **Policy evaluation** → lattice rule IDs + decision; emit final VEX statement.
7. DSSE‑sign each step; **link by previous segment hash** (spine = mini‑Merkle chain).

---

# Quick .NET 10 implementation hints

* **Canonical JSON:** `System.Text.Json` with deterministic ordering; pre‑normalize floats/timestamps.
* **DSSE:** wrap payloads, sign with your Authority service; store `key_id`, `sig`, `alg`.
* **Hashing:** SHA‑256 of canonical result; spine hash = hash(concat of segment hashes).
* **Replay manifests:** emit a single `scan.replay.json` containing feed versions, ruleset IDs, and all input hashes.

---

# Tiny UI contract for Angular

* Component: `ProofSpineComponent`

  * `@Input() spine: ProofSpine`
  * Emits: `replayRequested(spine_hash)`, `segmentOpened(segment_id)`
* Drawer shows: `inputs`, `result`, `attestation`, `reproduce` CTA.
* Badge colors map to verification state from backend (`verified/partial/missing/pending`).

---

# How it lands value fast

* Gives customers a **credible “not exploitable”** stance with audit‑ready proofs.
* Shortens investigations (SecOps, Dev, Compliance speak the same artifact).
* Creates a **moat**: deterministic, signed evidence chains—hard to copy with pure static lists.

If you want, I’ll draft the C# models, the DSSE signer interface, and the Angular component skeleton next.
Good, let’s turn the “proof spine” into something you can actually brief to devs, UX, and auditors as a concrete capability.

I’ll structure it around: domain model, lifecycle, storage, signing & trust, UX, and dev/testing guidelines.

---

## 1. Scope the Proof Spine precisely

### Core intent

A **Proof Spine** is the *minimal signed chain of reasoning* that justifies a VEX verdict for a given `(artifact, vulnerability)` pair. It must be:

* Deterministic: same inputs → bit-identical spine.
* Replayable: every step has enough context to re-run it.
* Verifiable: each step is DSSE-signed, chained by hashes.
* Decoupled: you can verify a spine even if Scanner/Vexer code changes later.

### Non-goals (so devs don’t overextend)

* Not a general logging system.
* Not a full provenance graph (that’s for your Proof-of-Integrity Graph).
* Not a full data warehouse of all intermediate findings. It’s a curated, compressed reasoning chain.

---

## 2. Domain model: from “nice idea” to strict contract

Think in terms of three primitives:

1. `ProofSpine`
2. `ProofSegment`
3. `ReplayManifest`

### 2.1 `ProofSpine` (aggregate root)

Per `(ArtifactId, VulnerabilityId, PolicyProfileId)` you have at most one **latest** active spine.

Key fields:

* `SpineId` (ULID / GUID): stable ID for references and URLs.
* `ArtifactId` (image digest, repo+tag, etc.).
* `VulnerabilityId` (CVE, GHSA, etc.).
* `PolicyProfileId` (which lattice/policy produced the verdict).
* `Segments[]` (ordered; see below).
* `Verdict` (`affected`, `not_affected`, `fixed`, `under_investigation`, etc.).
* `VerdictReason` (short machine code, e.g. `unreachable-code`, `guarded-runtime-config`).
* `RootHash` (hash of concatenated segment hashes).
* `ScanRunId` (link back to scan execution).
* `CreatedAt`, `SupersededBySpineId?`.

C# sketch:

```csharp
public sealed record ProofSpine(
    string SpineId,
    string ArtifactId,
    string VulnerabilityId,
    string PolicyProfileId,
    IReadOnlyList<ProofSegment> Segments,
    string Verdict,
    string VerdictReason,
    string RootHash,
    string ScanRunId,
    DateTimeOffset CreatedAt,
    string? SupersededBySpineId
);
```

### 2.2 `ProofSegment` (atomic evidence step)

Each segment represents **one logical transformation**:

Examples of `SegmentType`:

* `SBOM_SLICE` – “Which components are relevant?”
* `MATCH` – “Which SBOM component matches this vuln feed record?”
* `REACHABILITY` – “Is the vulnerable symbol reachable in this build?”
* `GUARD_ANALYSIS` – “Is this path gated by config/feature flag?”
* `RUNTIME_OBSERVATION` – “Was this code observed at runtime?”
* `POLICY_EVAL` – “How did the lattice/policy combine evidence?”

Fields:

* `SegmentId`
* `SegmentType`
* `Index` (0-based position in spine)
* `Inputs` (canonical JSON)
* `Result` (canonical JSON)
* `InputHash` (`SHA256(canonical(Inputs))`)
* `ResultHash`
* `PrevSegmentHash` (optional for first segment)
* `Envelope` (DSSE payload + signature)
* `ToolId`, `ToolVersion`
* `Status` (`verified`, `partial`, `invalid`, `unknown`)

C# sketch:

```csharp
public sealed record ProofSegment(
    string SegmentId,
    string SegmentType,
    int Index,
    string InputHash,
    string ResultHash,
    string? PrevSegmentHash,
    DsseEnvelope Envelope,
    string ToolId,
    string ToolVersion,
    string Status
);

public sealed record DsseEnvelope(
    string PayloadType,
    string PayloadBase64,
    IReadOnlyList<DsseSignature> Signatures
);

public sealed record DsseSignature(
    string KeyId,
    string SigBase64
);
```

### 2.3 `ReplayManifest` (reproducibility anchor)

A `ReplayManifest` is emitted per scan run and referenced by multiple spines:

* `ReplayManifestId`
* `Feeds` (names + versions + digests)
* `Rulesets` (reachability rules version, lattice policy version)
* `Tools` (scanner, sbomer, vexer versions)
* `Environment` (OS, arch, container image digest where the scan ran)

This is what your CLI will take:

```bash
stellaops scan --replay <ReplayManifestId> --artifact <ArtifactId> --vuln <VulnerabilityId>
```

---

## 3. Lifecycle: where the spine is built in Stella Ops

### 3.1 Producer components

The following services contribute segments:

* `Sbomer` → `SBOM_SLICE`
* `Scanner` → `MATCH`, maybe `RUNTIME_OBSERVATION` if it integrates runtime traces
* `Reachability Engine` inside `Scanner` / dedicated module → `REACHABILITY`
* `Guard Analyzer` (config/feature flag evaluator) → `GUARD_ANALYSIS`
* `Vexer/Excititor` → `POLICY_EVAL`, final verdict
* `Authority` → optional cross-signing / endorsement segment (`TRUST_ASSERTION`)

Important: each microservice **emits its own segments**, not a full spine. A small orchestrator (inside Vexer or a dedicated `ProofSpineBuilder`) collects, orders, and chains them.

### 3.2 Build sequence

Example for a “not affected due to guard” verdict:

1. `Sbomer` produces `SBOM_SLICE` segment for `(Artifact, Vuln)` and DSSE-signs it.
2. `Scanner` takes slice, produces `MATCH` segment (component X -> vuln Y).
3. `Reachability` produces `REACHABILITY` segment (symbol reachable or not).
4. `Guard Analyzer` produces `GUARD_ANALYSIS` segment (path is gated by `feature_x_enabled=false` under current policy context).
5. `Vexer` evaluates lattice, produces `POLICY_EVAL` segment with final VEX statement `not_affected`.
6. `ProofSpineBuilder`:

   * Sorts segments by predetermined order.
   * Chains `PrevSegmentHash`.
   * Computes `RootHash`.
   * Stores `ProofSpine` in canonical store and exposes it via API/GraphQL.

---

## 4. Storage & PostgreSQL patterns

You are moving more to Postgres for canonical data, so think:

### 4.1 Tables (conceptual)

`proof_spines`:

* `spine_id` (PK)
* `artifact_id`
* `vuln_id`
* `policy_profile_id`
* `verdict`
* `verdict_reason`
* `root_hash`
* `scan_run_id`
* `created_at`
* `superseded_by_spine_id` (nullable)
* `segment_count`

Indexes:

* `(artifact_id, vuln_id, policy_profile_id)`
* `(scan_run_id)`
* `(root_hash)`

`proof_segments`:

* `segment_id` (PK)
* `spine_id` (FK)
* `idx`
* `segment_type`
* `input_hash`
* `result_hash`
* `prev_segment_hash`
* `envelope` (bytea or text)
* `tool_id`
* `tool_version`
* `status`
* `created_at`

Optional `proof_segment_payloads` if you want fast JSONB search on `inputs` / `result`:

* `segment_id` (PK) FK
* `inputs_jsonb`
* `result_jsonb`

Guidelines:

* Use **append-only** semantics: never mutate segments; supersede by new spine.
* Partition `proof_spines` and `proof_segments` by time or `scan_run_id` if volume is large.
* Keep envelopes as raw bytes; only parse/validate on demand or asynchronously for indexing.

---

## 5. Signing, keys, and trust model

### 5.1 Signers

At minimum:

* One keypair per *service* (Sbomer, Scanner, Reachability, Vexer).
* Optional: vendor keys for imported spines/segments.

Key management:

* Keys and key IDs are owned by `Authority` service.
* Services obtain signing keys via short-lived tokens or integrate with HSM/Key vault under Authority control.
* Key rotation:

  * Keys have validity intervals.
  * Spines keep `KeyId` in each DSSE signature.
  * Authority maintains a trust table: which keys are trusted for which `SegmentType` and time window.

### 5.2 Verification flow

When UI loads a spine:

1. Fetch `ProofSpine` + `ProofSegments`.
2. For each segment:

   * Verify DSSE signature via Authority API.
   * Validate `PrevSegmentHash` integrity.
3. Compute `RootHash` and check against stored `RootHash`.
4. Expose per-segment `status` to UI: `verified`, `untrusted-key`, `signature-failed`, `hash-mismatch`.

This drives the badge colors in the UX.

---

## 6. UX: from “rail + pills” to full flows

Think of three primary UX contexts:

1. **Vulnerability detail → “Explain why not affected”**
2. **Audit view → “Show me all evidence behind this VEX statement”**
3. **Developer triage → “Where exactly did the reasoning go conservative?”**

### 6.1 Spine view patterns

For each `(artifact, vuln)`:

* **Top summary bar**

  * Verdict pill: `Not affected (guarded by runtime config)`
  * Confidence / verification status: e.g. `Proof verified`, `Partial proof`.
  * Links:

    * “Download Proof Spine” (JSON/DSSE bundle).
    * “Replay this analysis” (CLI snippet).

* **Spine stepper**

  * Horizontal list of segments (SBOM → Match → Reachability → Guard → Policy).
  * Each segment displays:

    * Type
    * Service name
    * Status (icon + color)
  * On click: open side drawer.

* **Side drawer (segment detail)**

  * `Who`: `ToolId`, `ToolVersion`, `KeyId`.
  * `When`: timestamps.
  * `Inputs`:

    * Pretty-printed subset with “Show canonical JSON” toggle.
  * `Result`:

    * Human-oriented short explanation + raw JSON view.
  * `Attestation`:

    * Signature summary: `Signature verified / Key untrusted / Invalid`.
    * `PrevSegmentHash` & `ResultHash` (shortened with copy icons).
  * “Run this step in isolation” button if you support it (nice-to-have).

### 6.2 Time-to-Evidence (TtE) integration

You already asked for guidelines on “Tracking UX Health with Time-to-Evidence”.

Use the spine as the data source:

* Measure `TtE` as:

  * `time_from_alert_opened_to_first_spine_view` OR
  * `time_from_alert_opened_to_verdict_understood`.
* Instrument events:

  * `spine_opened`, `segment_opened`, `segment_scrolled_to_end`, `replay_clicked`.
* Use this to spot UX bottlenecks:

  * Too many irrelevant segments.
  * Missing human explanations.
  * Overly verbose JSON.

### 6.3 Multiple paths and partial evidence

You might have:

* Static reachability: says “unreachable”.
* Runtime traces: not collected.
* Policy: chooses conservative path.

UI guidelines:

* Allow small branching visualization if you ever model alternative reasoning paths, but for v1:

  * Treat missing segments as explicit `pending` / `unknown`.
  * Show them as grey pills: “Runtime observation: not available”.

---

## 7. Replay & offline/air-gap story

For air-gapped Stella Ops this is one of your moats.

### 7.1 Manifest shape

`ReplayManifest` (JSON, canonicalized):

* `manifest_id`
* `generated_at`
* `tools`:

  * `{ "id": "Scanner", "version": "10.1.3", "image_digest": "..." }`
  * etc.
* `feeds`:

  * `{ "name": "nvd", "version": "2025-11-30T00:00:00Z", "hash": "..." }`
* `policies`:

  * `{ "policy_profile_id": "default-eu", "version": "3.4.0", "hash": "..." }`

CLI contract:

```bash
stellaops scan \
  --replay-manifest <id-or-file> \
  --artifact <image-digest> \
  --vuln <cve> \
  --explain
```

Replay guarantees:

* If the artifact and feeds are still available, replay reproduces:

  * identical segments,
  * identical `RootHash`,
  * identical verdict.
* If anything changed:

  * CLI clearly marks divergence: “Recomputed proof differs from stored spine (hash mismatch).”

### 7.2 Offline bundle integration

Your offline update kit should:

* Ship manifests alongside feed bundles.
* Keep a small index “manifest_id → bundle file”.
* Allow customers to verify that a spine produced 6 months ago used feed version X that they still have in archive.

---

## 8. Performance, dedup, and scaling

### 8.1 Dedup segments

Many artifacts share partial reasoning, e.g.:

* Same base image SBOM slice.
* Same reachability result for a shared library.

You have options:

1. **Simple v1:** keep segments embedded in spines. Optimize later.
2. **Advanced:** deduplicate by `ResultHash` + `SegmentType` + `ToolId`:

   * Store unique “segment payloads” in a table keyed by that combination.
   * `ProofSegment` then references payload via foreign key.

Guideline for now: instruct devs to design with **possible dedup** in mind (segment payloads should be referable).

### 8.2 Retention strategy

* Keep full spines for:

  * Recent scans (e.g., last 90 days) for triage.
  * Any spines that were exported to auditors or regulators.
* For older scans:

  * Option A: keep only `POLICY_EVAL` + `RootHash` + short summary.
  * Option B: archive full spines to object storage (S3/minio) keyed by `RootHash`.

---

## 9. Security & multi-tenant boundaries

Stella Ops will likely serve many customers / environments.

Guidelines:

* `SpineId` is globally unique, but all queries must be scope-checked by:

  * `TenantId`
  * `EnvironmentId`
* Authority verifies not only signatures, but also **key scopes**:

  * Key X is only allowed to sign for Tenant T / Environment E, or for system-wide tools.
* Never leak:

  * File paths,
  * Internal IPs,
  * Customer-specific configs,
    in the human-friendly explanation. Those can stay in the canonical JSON, which is exposed only in advanced / audit mode.

---

## 10. Developer & tester guidelines

### 10.1 For implementors (C# / .NET 10)

* Use a **single deterministic JSON serializer** (e.g. wrapper around `System.Text.Json`) with:

  * Stable property order.
  * Standardized timestamp format (UTC ISO 8601).
  * Explicit numeric formats (no locale-dependent decimals).
* Before signing:

  * Canonicalize JSON.
  * Hash bytes directly.
* Never change canonicalization semantics in a minor version. If you must, bump a major version and record it in `ReplayManifest`.

### 10.2 For test engineers

Build a curated suite of fixture scenarios:

1. “Straightforward not affected”:

   * Unreachable symbol, no runtime data, conservative policy: still `not_affected` due to unreachable.
2. “Guarded at runtime”:

   * Reachable symbol, but guard based on config → `not_affected`.
3. “Missing segment”:

   * Remove `REACHABILITY` segment → policy should downgrade to `affected` or `under_investigation`.
4. “Signature tampering”:

   * Flip a byte in one DSSE payload → UI must show `invalid` and mark entire spine as compromised.
5. “Key revocation”:

   * Mark a key untrusted → segments signed with it become `untrusted-key` and spine is partially verified.

Provide golden JSON for:

* `ProofSpine` object.
* Each `ProofSegment` envelope.
* Expected `RootHash`.
* Expected UI status per segment.

---

## 11. How this ties into your moats

This Proof Spine is not just “nice UX”:

* It is the **concrete substrate** for:

  * Trust Algebra Studio (the lattice engine acts on segments and outputs `POLICY_EVAL` segments).
  * Proof-Market Ledger (publish `RootHash` + minimal metadata).
  * Deterministic, replayable scans (spine + manifest).
* Competitors can show “reasons”, but you are explicitly providing:

  * Signed, chain-of-evidence reasoning,
  * With deterministic replay,
  * Packaged for regulators and procurement.

---

If you want, next step I can draft:

* A proto/JSON schema for `ProofSpine` bundles for export/import.
* A minimal set of REST/GraphQL endpoints for querying spines from UI and external auditors.