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The Schema Vault is ChameleonDB’s core feature for treating schemas as first-class, immutable artifacts with explicit integrity guarantees.

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Overview

Unlike traditional databases that treat schema evolution as an auxiliary concern, ChameleonDB governs schemas at runtime through versioning, cryptographic integrity, and automatic verification.
The Schema Vault auto-initializes on first migrate with zero configuration required.

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The Problem

Modern database systems enforce strong guarantees over data but treat schema evolution informally:
  • Schema drift happens silently over time
  • Migration failures leave databases in unknown states
  • Authority for schema changes is implicit, not enforced
  • Audit trails are external, incomplete, or missing
  • Rollback is manual and error-prone

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The Solution

ChameleonDB’s Schema Vault provides: ✅ Immutable schema versions — Tamper-proof with SHA256 hashing
✅ Integrity verification — Automatic checks before every operation
✅ Complete audit trail — Append-only log, never deleted
✅ Zero-config vault — Auto-initializes on first migrate
✅ Lineage tracking — Parent version references

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Vault Structure

The Schema Vault lives in the .chameleon/vault/ directory: 
.chameleon/vault/
├── manifest.json       # Current version + history
├── integrity.log       # Append-only audit trail
├── versions/
│   ├── v001.json      # Immutable snapshot
│   └── v002.json
└── hashes/
    ├── v001.hash      # SHA256 verification
    └── v002.hash

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manifest.json

Tracks the current version and complete version history: 
{
  "current_version": "v002",
  "history": [
    {
      "version": "v001",
      "hash": "3f2a8b9c...",
      "date": "2026-02-20T10:30:00Z",
      "author": "dperalta",
      "parent": null
    },
    {
      "version": "v002",
      "hash": "7d4e1c2a...",
      "date": "2026-02-20T15:45:00Z",
      "author": "dperalta",
      "parent": "v001"
    }
  ]
}

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versions/

Contains immutable schema snapshots. Once registered, these files are never modified. Example v001.json: 
{
  "version": "v001",
  "entities": [
    {
      "name": "User",
      "fields": [
        {"name": "id", "type": "uuid", "primary": true},
        {"name": "email", "type": "string", "unique": true},
        {"name": "name", "type": "string"}
      ]
    }
  ]
}

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hashes/

Stores SHA256 hashes for tamper detection. Each version has a corresponding .hash file.

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integrity.log

Append-only audit trail recording all vault operations: 
2026-02-20T10:30:00Z [REGISTER] v001 (hash: 3f2a8b9c...) by dperalta
2026-02-20T10:30:15Z [VERIFY]   v001 ✓ OK
2026-02-20T15:45:00Z [REGISTER] v002 (hash: 7d4e1c2a..., parent: v001) by dperalta
2026-02-20T15:45:10Z [VERIFY]   v002 ✓ OK
The integrity.log is never deleted. It provides complete forensics for compliance and debugging.

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How It Works

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1. Define Your Schema

Create a schema.cham file with versioned entities: 
entity User {
    id: uuid primary,
    email: string unique,
    name: string,
    posts: [Post] via author_id,
}

entity Post {
    id: uuid primary,
    title: string,
    content: string,
    published: bool,
    author_id: uuid,
    author: User,
}

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2. Initialize the Vault

chameleon init                  # Creates .chameleon/vault/
The vault is created with readonly mode by default for security.

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3. Apply Migration

chameleon migrate --apply       # Registers v001, applies migration
This automatically:
  • Computes SHA256 hash of the schema
  • Registers it as version v001
  • Saves snapshot to vault/versions/v001.json
  • Saves hash to vault/hashes/v001.hash
  • Updates manifest.json
  • Logs operation to integrity.log
  • Applies migration to database

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4. Automatic Verification

Every operation verifies integrity: 
$ chameleon migrate

🔍 Verifying schema integrity...
   ✓ Current: v001 (3f2a8b9c...)
   ✓ No tampering detected

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5. Tamper Detection

If someone modifies vault files: 
❌ INTEGRITY VIOLATION DETECTED
   • v001.json: hash mismatch
   🚨 Schema vault has been modified!
   ❌ Migration aborted for safety
Integrity violations always abort operations. This is a critical safety feature.

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Version History

View the complete version history: 
$ chameleon journal schema

📖 Schema Version History

v002 (current) ✓
├─ Hash: 7d4e1c2a...
├─ Date: 2026-02-20 15:45:00
├─ Author: dperalta
├─ Changes: Added age field to User
└─ Parent: v001

v001
├─ Hash: 3f2a8b9c...
├─ Date: 2026-02-20 10:30:00
├─ Author: dperalta
├─ Changes: Initial schema
└─ Parent: none

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Workflow

The complete vault registration workflow: 
1. User modifies schema.cham
2. chameleon migrate detects changes
3. Compute SHA256 hash
4. Register as v002 (parent: v001)
5. Save snapshot to vault/versions/v002.json
6. Save hash to vault/hashes/v002.hash
7. Update manifest.json
8. Log to integrity.log
9. Apply migration to database

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Security Model

The vault uses multiple layers of security:
  1. OS Permissions - File access control (0700)
  2. Hash Integrity - SHA256 tamper detection
  3. Integrity Modes - Runtime access control (see Integrity Modes)
  4. Vault Enforcement - No schema bypass in v1.0+
  5. Audit Trail - Complete forensics
In v1.0+, the Go engine only loads schemas from the vault. Direct file loading is disabled for security.

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Migration Registration

Every migration creates a new version: 
$ chameleon migrate --apply

📦 Registering new schema version...
   ✓ Registered as v002 (hash: 7d4e1c2a...)
   ✓ Parent: v001

✅ Migration applied successfully
✅ Schema v002 locked in vault

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Features

  • ✅ Immutable snapshots - Once registered, never modified
  • ✅ SHA256 hash verification - Tamper detection on every operation
  • ✅ Lineage tracking - Parent version references
  • ✅ Automatic registration - On every migrate
  • ✅ Complete audit trail - integrity.log never deleted
  • ✅ Zero configuration - Auto-initializes on first use

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Best Practices

  1. Never manually edit vault files - Always use chameleon CLI
  2. Commit vault to version control - Track schema history alongside code
  3. Set mode password - Protect against unauthorized schema changes
  4. Review integrity.log regularly - Monitor for unexpected changes
  5. Use readonly mode in production - Prevent accidental modifications

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Commands

# Initialize vault
chameleon init

# View version history
chameleon journal schema

# View specific version
chameleon journal schema v002

# Verify integrity
chameleon verify

# View vault status
chameleon status

# View integrity log
cat .chameleon/vault/integrity.log

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Next Steps