From f26676db2c7a0a771e77781fe6f8c199b99993da Mon Sep 17 00:00:00 2001
From: anonpenguin23 <rimrh1o0@tuta.com>
Date: Fri, 27 Feb 2026 15:22:51 +0200
Subject: [PATCH] feat: add sandbox command and vault guardian build

- integrate Zig-built vault-guardian into cross-compile process
- add `orama sandbox` for ephemeral Hetzner Cloud clusters
- update docs for `orama node` subcommands and new guides
---
 README.md                                    |  14 +-
 cmd/cli/root.go                              |   4 +
 docs/COMMON_PROBLEMS.md                      |  16 +-
 pkg/cli/build/builder.go                     | 108 +++-
 pkg/environments/production/config.go        |  24 +
 pkg/environments/production/orchestrator.go  |  28 +-
 pkg/environments/production/prebuilt.go      |   2 +
 pkg/environments/production/provisioner.go   |   2 +
 pkg/environments/production/services.go      |  37 ++
 pkg/gateway/gateway.go                       |   5 +
 pkg/gateway/handlers/vault/handlers.go       | 132 +++++
 pkg/gateway/handlers/vault/health_handler.go | 116 +++++
 pkg/gateway/handlers/vault/pull_handler.go   | 183 +++++++
 pkg/gateway/handlers/vault/push_handler.go   | 168 +++++++
 pkg/gateway/handlers/vault/rate_limiter.go   | 120 +++++
 pkg/gateway/middleware.go                    |   5 +
 pkg/gateway/routes.go                        |   8 +
 pkg/shamir/field.go                          |  82 +++
 pkg/shamir/shamir.go                         | 150 ++++++
 pkg/shamir/shamir_test.go                    | 501 +++++++++++++++++++
 20 files changed, 1669 insertions(+), 36 deletions(-)
 create mode 100644 pkg/gateway/handlers/vault/handlers.go
 create mode 100644 pkg/gateway/handlers/vault/health_handler.go
 create mode 100644 pkg/gateway/handlers/vault/pull_handler.go
 create mode 100644 pkg/gateway/handlers/vault/push_handler.go
 create mode 100644 pkg/gateway/handlers/vault/rate_limiter.go
 create mode 100644 pkg/shamir/field.go
 create mode 100644 pkg/shamir/shamir.go
 create mode 100644 pkg/shamir/shamir_test.go

diff --git a/README.md b/README.md
index 2b416c2..d8119d6 100644
--- a/README.md
+++ b/README.md
@@ -349,13 +349,13 @@ All configuration lives in `~/.orama/`:
 
 ```bash
 # Check status
-systemctl status orama-node
+sudo orama node status
 
 # View logs
-journalctl -u orama-node -f
+orama node logs node --follow
 
 # Check log files
-tail -f /opt/orama/.orama/logs/node.log
+sudo orama node doctor
 ```
 
 ### Port Conflicts
@@ -417,9 +417,11 @@ See `openapi/gateway.yaml` for complete API specification.
 - **[Deployment Guide](docs/DEPLOYMENT_GUIDE.md)** - Deploy React, Next.js, Go apps and manage databases
 - **[Architecture Guide](docs/ARCHITECTURE.md)** - System architecture and design patterns
 - **[Client SDK](docs/CLIENT_SDK.md)** - Go SDK documentation and examples
-- **[Gateway API](docs/GATEWAY_API.md)** - Complete HTTP API reference
-- **[Security Deployment](docs/SECURITY_DEPLOYMENT_GUIDE.md)** - Production security hardening
-- **[Testing Plan](docs/TESTING_PLAN.md)** - Comprehensive testing strategy and implementation
+- **[Monitoring](docs/MONITORING.md)** - Cluster monitoring and health checks
+- **[Inspector](docs/INSPECTOR.md)** - Deep subsystem health inspection
+- **[Serverless Functions](docs/SERVERLESS.md)** - WASM serverless with host functions
+- **[WebRTC](docs/WEBRTC.md)** - Real-time communication setup
+- **[Common Problems](docs/COMMON_PROBLEMS.md)** - Troubleshooting known issues
 
 ## Resources
 
diff --git a/cmd/cli/root.go b/cmd/cli/root.go
index 266fc9b..0f27fdd 100644
--- a/cmd/cli/root.go
+++ b/cmd/cli/root.go
@@ -18,6 +18,7 @@ import (
 	"github.com/DeBrosOfficial/network/pkg/cli/cmd/monitorcmd"
 	"github.com/DeBrosOfficial/network/pkg/cli/cmd/namespacecmd"
 	"github.com/DeBrosOfficial/network/pkg/cli/cmd/node"
+	"github.com/DeBrosOfficial/network/pkg/cli/cmd/sandboxcmd"
 )
 
 // version metadata populated via -ldflags at build time
@@ -87,6 +88,9 @@ and interacting with the Orama distributed network.`,
 	// Build command (cross-compile binary archive)
 	rootCmd.AddCommand(buildcmd.Cmd)
 
+	// Sandbox command (ephemeral Hetzner Cloud clusters)
+	rootCmd.AddCommand(sandboxcmd.Cmd)
+
 	return rootCmd
 }
 
diff --git a/docs/COMMON_PROBLEMS.md b/docs/COMMON_PROBLEMS.md
index f54c938..ae6d9ff 100644
--- a/docs/COMMON_PROBLEMS.md
+++ b/docs/COMMON_PROBLEMS.md
@@ -32,7 +32,7 @@ wg set wg0 peer <NodeA-pubkey> remove
 wg set wg0 peer <NodeA-pubkey> endpoint <NodeA-public-ip>:51820 allowed-ips <NodeA-wg-ip>/32 persistent-keepalive 25
 ```
 
-Then restart services: `sudo orama prod restart`
+Then restart services: `sudo orama node restart`
 
 You can find peer public keys with `wg show wg0`.
 
@@ -46,7 +46,7 @@ cat /opt/orama/.orama/data/namespaces/<name>/configs/olric-*.yaml
 
 If `bindAddr` is `0.0.0.0`, the node will try to bind to IPv6 on dual-stack hosts, breaking memberlist gossip.
 
-**Fix:** Edit the YAML to use the node's WireGuard IP (run `ip addr show wg0` to find it), then restart: `sudo orama prod restart`
+**Fix:** Edit the YAML to use the node's WireGuard IP (run `ip addr show wg0` to find it), then restart: `sudo orama node restart`
 
 This was fixed in code (BindAddr validation in `SpawnOlric`), so new namespaces won't have this issue.
 
@@ -82,7 +82,7 @@ olric_servers:
   - "10.0.0.Z:10002"
 ```
 
-Then: `sudo orama prod restart`
+Then: `sudo orama node restart`
 
 This was fixed in code, so new namespaces get the correct config.
 
@@ -90,7 +90,7 @@ This was fixed in code, so new namespaces get the correct config.
 
 ## 3. Namespace not restoring after restart (missing cluster-state.json)
 
-**Symptom:** After `orama prod restart`, the namespace services don't come back because `RestoreLocalClustersFromDisk` has no state file.
+**Symptom:** After `orama node restart`, the namespace services don't come back because `RestoreLocalClustersFromDisk` has no state file.
 
 **Check:**
 
@@ -117,9 +117,9 @@ This was fixed in code — `ProvisionCluster` now saves state to all nodes (incl
 
 ## 4. Namespace gateway processes not restarting after upgrade
 
-**Symptom:** After `orama upgrade --restart` or `orama prod restart`, namespace gateway/olric/rqlite services don't start.
+**Symptom:** After `orama upgrade --restart` or `orama node restart`, namespace gateway/olric/rqlite services don't start.
 
-**Cause:** `orama prod stop` disables systemd template services (`orama-namespace-gateway@<name>.service`). They have `PartOf=orama-node.service`, but that only propagates restart to **enabled** services.
+**Cause:** `orama node stop` disables systemd template services (`orama-namespace-gateway@<name>.service`). They have `PartOf=orama-node.service`, but that only propagates restart to **enabled** services.
 
 **Fix:** Re-enable the services before restarting:
 
@@ -127,7 +127,7 @@ This was fixed in code — `ProvisionCluster` now saves state to all nodes (incl
 systemctl enable orama-namespace-rqlite@<name>.service
 systemctl enable orama-namespace-olric@<name>.service
 systemctl enable orama-namespace-gateway@<name>.service
-sudo orama prod restart
+sudo orama node restart
 ```
 
 This was fixed in code — the upgrade orchestrator now re-enables `@` services before restarting.
@@ -152,7 +152,7 @@ ssh -n user@host 'command'
 
 ## General Debugging Tips
 
-- **Always use `sudo orama prod restart`** instead of raw `systemctl` commands
+- **Always use `sudo orama node restart`** instead of raw `systemctl` commands
 - **Namespace data lives at:** `/opt/orama/.orama/data/namespaces/<name>/`
 - **Check service logs:** `journalctl -u orama-namespace-olric@<name>.service --no-pager -n 50`
 - **Check WireGuard:** `wg show wg0` — look for recent handshakes and transfer bytes
diff --git a/pkg/cli/build/builder.go b/pkg/cli/build/builder.go
index de82016..4514f6b 100644
--- a/pkg/cli/build/builder.go
+++ b/pkg/cli/build/builder.go
@@ -71,48 +71,53 @@ func (b *Builder) Build() error {
 		return fmt.Errorf("failed to build orama binaries: %w", err)
 	}
 
-	// Step 2: Cross-compile Olric
+	// Step 2: Cross-compile Vault Guardian (Zig)
+	if err := b.buildVaultGuardian(); err != nil {
+		return fmt.Errorf("failed to build vault-guardian: %w", err)
+	}
+
+	// Step 3: Cross-compile Olric
 	if err := b.buildOlric(); err != nil {
 		return fmt.Errorf("failed to build olric: %w", err)
 	}
 
-	// Step 3: Cross-compile IPFS Cluster
+	// Step 4: Cross-compile IPFS Cluster
 	if err := b.buildIPFSCluster(); err != nil {
 		return fmt.Errorf("failed to build ipfs-cluster: %w", err)
 	}
 
-	// Step 4: Build CoreDNS with RQLite plugin
+	// Step 5: Build CoreDNS with RQLite plugin
 	if err := b.buildCoreDNS(); err != nil {
 		return fmt.Errorf("failed to build coredns: %w", err)
 	}
 
-	// Step 5: Build Caddy with Orama DNS module
+	// Step 6: Build Caddy with Orama DNS module
 	if err := b.buildCaddy(); err != nil {
 		return fmt.Errorf("failed to build caddy: %w", err)
 	}
 
-	// Step 6: Download pre-built IPFS Kubo
+	// Step 7: Download pre-built IPFS Kubo
 	if err := b.downloadIPFS(); err != nil {
 		return fmt.Errorf("failed to download ipfs: %w", err)
 	}
 
-	// Step 7: Download pre-built RQLite
+	// Step 8: Download pre-built RQLite
 	if err := b.downloadRQLite(); err != nil {
 		return fmt.Errorf("failed to download rqlite: %w", err)
 	}
 
-	// Step 8: Copy systemd templates
+	// Step 9: Copy systemd templates
 	if err := b.copySystemdTemplates(); err != nil {
 		return fmt.Errorf("failed to copy systemd templates: %w", err)
 	}
 
-	// Step 9: Generate manifest
+	// Step 10: Generate manifest
 	manifest, err := b.generateManifest()
 	if err != nil {
 		return fmt.Errorf("failed to generate manifest: %w", err)
 	}
 
-	// Step 10: Create archive
+	// Step 11: Create archive
 	outputPath := b.flags.Output
 	if outputPath == "" {
 		outputPath = fmt.Sprintf("/tmp/orama-%s-linux-%s.tar.gz", b.version, b.flags.Arch)
@@ -130,7 +135,7 @@ func (b *Builder) Build() error {
 }
 
 func (b *Builder) buildOramaBinaries() error {
-	fmt.Println("[1/7] Cross-compiling Orama binaries...")
+	fmt.Println("[1/8] Cross-compiling Orama binaries...")
 
 	ldflags := fmt.Sprintf("-s -w -X 'main.version=%s' -X 'main.commit=%s' -X 'main.date=%s'",
 		b.version, b.commit, b.date)
@@ -177,8 +182,79 @@ func (b *Builder) buildOramaBinaries() error {
 	return nil
 }
 
+func (b *Builder) buildVaultGuardian() error {
+	fmt.Println("[2/8] Cross-compiling Vault Guardian (Zig)...")
+
+	// Ensure zig is available
+	if _, err := exec.LookPath("zig"); err != nil {
+		return fmt.Errorf("zig not found in PATH — install from https://ziglang.org/download/")
+	}
+
+	// Vault source is sibling to orama project
+	vaultDir := filepath.Join(b.projectDir, "..", "orama-vault")
+	if _, err := os.Stat(filepath.Join(vaultDir, "build.zig")); err != nil {
+		return fmt.Errorf("vault source not found at %s — expected orama-vault as sibling directory: %w", vaultDir, err)
+	}
+
+	// Map Go arch to Zig target triple
+	var zigTarget string
+	switch b.flags.Arch {
+	case "amd64":
+		zigTarget = "x86_64-linux-musl"
+	case "arm64":
+		zigTarget = "aarch64-linux-musl"
+	default:
+		return fmt.Errorf("unsupported architecture for vault: %s", b.flags.Arch)
+	}
+
+	if b.flags.Verbose {
+		fmt.Printf("  zig build -Dtarget=%s -Doptimize=ReleaseSafe\n", zigTarget)
+	}
+
+	cmd := exec.Command("zig", "build",
+		fmt.Sprintf("-Dtarget=%s", zigTarget),
+		"-Doptimize=ReleaseSafe")
+	cmd.Dir = vaultDir
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("zig build failed: %w", err)
+	}
+
+	// Copy output binary to build bin dir
+	src := filepath.Join(vaultDir, "zig-out", "bin", "vault-guardian")
+	dst := filepath.Join(b.binDir, "vault-guardian")
+	if err := copyFile(src, dst); err != nil {
+		return fmt.Errorf("failed to copy vault-guardian binary: %w", err)
+	}
+
+	fmt.Println("  ✓ vault-guardian")
+	return nil
+}
+
+// copyFile copies a file from src to dst, preserving executable permissions.
+func copyFile(src, dst string) error {
+	srcFile, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer srcFile.Close()
+
+	dstFile, err := os.OpenFile(dst, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0755)
+	if err != nil {
+		return err
+	}
+	defer dstFile.Close()
+
+	if _, err := srcFile.WriteTo(dstFile); err != nil {
+		return err
+	}
+	return nil
+}
+
 func (b *Builder) buildOlric() error {
-	fmt.Printf("[2/7] Cross-compiling Olric %s...\n", constants.OlricVersion)
+	fmt.Printf("[3/8] Cross-compiling Olric %s...\n", constants.OlricVersion)
 
 	cmd := exec.Command("go", "install",
 		fmt.Sprintf("github.com/olric-data/olric/cmd/olric-server@%s", constants.OlricVersion))
@@ -197,7 +273,7 @@ func (b *Builder) buildOlric() error {
 }
 
 func (b *Builder) buildIPFSCluster() error {
-	fmt.Printf("[3/7] Cross-compiling IPFS Cluster %s...\n", constants.IPFSClusterVersion)
+	fmt.Printf("[4/8] Cross-compiling IPFS Cluster %s...\n", constants.IPFSClusterVersion)
 
 	cmd := exec.Command("go", "install",
 		fmt.Sprintf("github.com/ipfs-cluster/ipfs-cluster/cmd/ipfs-cluster-service@%s", constants.IPFSClusterVersion))
@@ -216,7 +292,7 @@ func (b *Builder) buildIPFSCluster() error {
 }
 
 func (b *Builder) buildCoreDNS() error {
-	fmt.Printf("[4/7] Building CoreDNS %s with RQLite plugin...\n", constants.CoreDNSVersion)
+	fmt.Printf("[5/8] Building CoreDNS %s with RQLite plugin...\n", constants.CoreDNSVersion)
 
 	buildDir := filepath.Join(b.tmpDir, "coredns-build")
 
@@ -363,7 +439,7 @@ rqlite:rqlite
 }
 
 func (b *Builder) buildCaddy() error {
-	fmt.Printf("[5/7] Building Caddy %s with Orama DNS module...\n", constants.CaddyVersion)
+	fmt.Printf("[6/8] Building Caddy %s with Orama DNS module...\n", constants.CaddyVersion)
 
 	// Ensure xcaddy is available
 	if _, err := exec.LookPath("xcaddy"); err != nil {
@@ -429,7 +505,7 @@ require (
 }
 
 func (b *Builder) downloadIPFS() error {
-	fmt.Printf("[6/7] Downloading IPFS Kubo %s...\n", constants.IPFSKuboVersion)
+	fmt.Printf("[7/8] Downloading IPFS Kubo %s...\n", constants.IPFSKuboVersion)
 
 	arch := b.flags.Arch
 	tarball := fmt.Sprintf("kubo_%s_linux-%s.tar.gz", constants.IPFSKuboVersion, arch)
@@ -450,7 +526,7 @@ func (b *Builder) downloadIPFS() error {
 }
 
 func (b *Builder) downloadRQLite() error {
-	fmt.Printf("[7/7] Downloading RQLite %s...\n", constants.RQLiteVersion)
+	fmt.Printf("[8/8] Downloading RQLite %s...\n", constants.RQLiteVersion)
 
 	arch := b.flags.Arch
 	tarball := fmt.Sprintf("rqlite-v%s-linux-%s.tar.gz", constants.RQLiteVersion, arch)
diff --git a/pkg/environments/production/config.go b/pkg/environments/production/config.go
index 3bf6cd1..8de319a 100644
--- a/pkg/environments/production/config.go
+++ b/pkg/environments/production/config.go
@@ -194,6 +194,30 @@ func (cg *ConfigGenerator) GenerateNodeConfig(peerAddresses []string, vpsIP stri
 	return templates.RenderNodeConfig(data)
 }
 
+// GenerateVaultConfig generates vault.yaml configuration for the Vault Guardian.
+// The vault config uses key=value format (not YAML, despite the file extension).
+// Peer discovery is dynamic via RQLite — no static peer list needed.
+func (cg *ConfigGenerator) GenerateVaultConfig(vpsIP string) string {
+	dataDir := filepath.Join(cg.oramaDir, "data", "vault")
+
+	// Bind to WireGuard IP so vault is only accessible over the overlay network.
+	// If no WG IP is provided, bind to localhost as a safe default.
+	bindAddr := "127.0.0.1"
+	if vpsIP != "" {
+		bindAddr = vpsIP
+	}
+
+	return fmt.Sprintf(`# Vault Guardian Configuration
+# Generated by orama node install
+
+listen_address = %s
+client_port = 7500
+peer_port = 7501
+data_dir = %s
+rqlite_url = http://127.0.0.1:5001
+`, bindAddr, dataDir)
+}
+
 // GenerateGatewayConfig generates gateway.yaml configuration
 func (cg *ConfigGenerator) GenerateGatewayConfig(peerAddresses []string, enableHTTPS bool, domain string, olricServers []string) (string, error) {
 	tlsCacheDir := ""
diff --git a/pkg/environments/production/orchestrator.go b/pkg/environments/production/orchestrator.go
index 7e5d371..65dd7c8 100644
--- a/pkg/environments/production/orchestrator.go
+++ b/pkg/environments/production/orchestrator.go
@@ -573,6 +573,14 @@ func (ps *ProductionSetup) Phase4GenerateConfigs(peerAddresses []string, vpsIP s
 	}
 	ps.logf("  ✓ Olric config generated")
 
+	// Vault Guardian config
+	vaultConfig := ps.configGenerator.GenerateVaultConfig(vpsIP)
+	vaultConfigPath := filepath.Join(ps.oramaDir, "data", "vault", "vault.yaml")
+	if err := os.WriteFile(vaultConfigPath, []byte(vaultConfig), 0644); err != nil {
+		return fmt.Errorf("failed to save vault config: %w", err)
+	}
+	ps.logf("  ✓ Vault config generated")
+
 	// Configure CoreDNS (if baseDomain is provided - this is the zone name)
 	// CoreDNS uses baseDomain (e.g., "dbrs.space") as the authoritative zone
 	dnsZone := baseDomain
@@ -667,6 +675,13 @@ func (ps *ProductionSetup) Phase5CreateSystemdServices(enableHTTPS bool) error {
 	}
 	ps.logf("  ✓ Node service created: orama-node.service (with embedded gateway)")
 
+	// Vault Guardian service
+	vaultUnit := ps.serviceGenerator.GenerateVaultService()
+	if err := ps.serviceController.WriteServiceUnit("orama-vault.service", vaultUnit); err != nil {
+		return fmt.Errorf("failed to write Vault service: %w", err)
+	}
+	ps.logf("  ✓ Vault service created: orama-vault.service")
+
 	// Anyone Relay service (only created when --anyone-relay flag is used)
 	// A node must run EITHER relay OR client, never both. When writing one
 	// mode's service, we remove the other to prevent conflicts (they share
@@ -725,7 +740,7 @@ func (ps *ProductionSetup) Phase5CreateSystemdServices(enableHTTPS bool) error {
 	// Enable services (unified names - no bootstrap/node distinction)
 	// Note: orama-gateway.service is no longer needed - each node has an embedded gateway
 	// Note: orama-rqlite.service is NOT created - RQLite is managed by each node internally
-	services := []string{"orama-ipfs.service", "orama-ipfs-cluster.service", "orama-olric.service", "orama-node.service"}
+	services := []string{"orama-ipfs.service", "orama-ipfs-cluster.service", "orama-olric.service", "orama-vault.service", "orama-node.service"}
 
 	// Add Anyone service if configured (relay or client)
 	if ps.IsAnyoneRelay() {
@@ -756,8 +771,8 @@ func (ps *ProductionSetup) Phase5CreateSystemdServices(enableHTTPS bool) error {
 	// services pick up new configs even if already running from a previous install)
 	ps.logf("  Starting services...")
 
-	// Start infrastructure first (IPFS, Olric, Anyone) - RQLite is managed internally by each node
-	infraServices := []string{"orama-ipfs.service", "orama-olric.service"}
+	// Start infrastructure first (IPFS, Olric, Vault, Anyone) - RQLite is managed internally by each node
+	infraServices := []string{"orama-ipfs.service", "orama-olric.service", "orama-vault.service"}
 
 	// Add Anyone service if configured (relay or client)
 	if ps.IsAnyoneRelay() {
@@ -977,12 +992,13 @@ func (ps *ProductionSetup) LogSetupComplete(peerID string) {
 	ps.logf("  %s/logs/olric.log", ps.oramaDir)
 	ps.logf("  %s/logs/node.log", ps.oramaDir)
 	ps.logf("  %s/logs/gateway.log", ps.oramaDir)
+	ps.logf("  %s/logs/vault.log", ps.oramaDir)
 
 	// Anyone mode-specific logs and commands
 	if ps.IsAnyoneRelay() {
 		ps.logf("  /var/log/anon/notices.log (Anyone Relay)")
 		ps.logf("\nStart All Services:")
-		ps.logf("  systemctl start orama-ipfs orama-ipfs-cluster orama-olric orama-anyone-relay orama-node")
+		ps.logf("  systemctl start orama-ipfs orama-ipfs-cluster orama-olric orama-vault orama-anyone-relay orama-node")
 		ps.logf("\nAnyone Relay Operator:")
 		ps.logf("  ORPort: %d", ps.anyoneRelayConfig.ORPort)
 		ps.logf("  Wallet: %s", ps.anyoneRelayConfig.Wallet)
@@ -991,10 +1007,10 @@ func (ps *ProductionSetup) LogSetupComplete(peerID string) {
 		ps.logf("  IMPORTANT: You need 100 $ANYONE tokens in your wallet to receive rewards")
 	} else if ps.IsAnyoneClient() {
 		ps.logf("\nStart All Services:")
-		ps.logf("  systemctl start orama-ipfs orama-ipfs-cluster orama-olric orama-anyone-client orama-node")
+		ps.logf("  systemctl start orama-ipfs orama-ipfs-cluster orama-olric orama-vault orama-anyone-client orama-node")
 	} else {
 		ps.logf("\nStart All Services:")
-		ps.logf("  systemctl start orama-ipfs orama-ipfs-cluster orama-olric orama-node")
+		ps.logf("  systemctl start orama-ipfs orama-ipfs-cluster orama-olric orama-vault orama-node")
 	}
 
 	ps.logf("\nVerify Installation:")
diff --git a/pkg/environments/production/prebuilt.go b/pkg/environments/production/prebuilt.go
index 689b8ba..04d4233 100644
--- a/pkg/environments/production/prebuilt.go
+++ b/pkg/environments/production/prebuilt.go
@@ -127,6 +127,8 @@ func (ps *ProductionSetup) deployPreBuiltBinaries(manifest *PreBuiltManifest) er
 		{name: "coredns", dest: "/usr/local/bin/coredns"},
 		{name: "caddy", dest: "/usr/bin/caddy"},
 	}
+	// Note: vault-guardian stays at /opt/orama/bin/ (from archive extraction)
+	// and is referenced by absolute path in the systemd service — no copy needed.
 
 	for _, bin := range binaries {
 		srcPath := filepath.Join(OramaArchiveBin, bin.name)
diff --git a/pkg/environments/production/provisioner.go b/pkg/environments/production/provisioner.go
index 259e213..97e3089 100644
--- a/pkg/environments/production/provisioner.go
+++ b/pkg/environments/production/provisioner.go
@@ -34,6 +34,7 @@ func (fp *FilesystemProvisioner) EnsureDirectoryStructure() error {
 		filepath.Join(fp.oramaDir, "data", "ipfs", "repo"),
 		filepath.Join(fp.oramaDir, "data", "ipfs-cluster"),
 		filepath.Join(fp.oramaDir, "data", "rqlite"),
+		filepath.Join(fp.oramaDir, "data", "vault"),
 		filepath.Join(fp.oramaDir, "logs"),
 		filepath.Join(fp.oramaDir, "tls-cache"),
 		filepath.Join(fp.oramaDir, "backups"),
@@ -65,6 +66,7 @@ func (fp *FilesystemProvisioner) EnsureDirectoryStructure() error {
 		"ipfs.log",
 		"ipfs-cluster.log",
 		"node.log",
+		"vault.log",
 		"anyone-client.log",
 	}
 
diff --git a/pkg/environments/production/services.go b/pkg/environments/production/services.go
index 0070cb9..2e47f66 100644
--- a/pkg/environments/production/services.go
+++ b/pkg/environments/production/services.go
@@ -214,6 +214,43 @@ WantedBy=multi-user.target
 `, ssg.oramaHome, ssg.oramaDir, configFile, logFile)
 }
 
+// GenerateVaultService generates the Orama Vault Guardian systemd unit.
+// The vault guardian runs on every node, storing Shamir secret shares.
+// It binds to the WireGuard overlay only (no public exposure).
+func (ssg *SystemdServiceGenerator) GenerateVaultService() string {
+	logFile := filepath.Join(ssg.oramaDir, "logs", "vault.log")
+	dataDir := filepath.Join(ssg.oramaDir, "data", "vault")
+
+	return fmt.Sprintf(`[Unit]
+Description=Orama Vault Guardian
+After=network-online.target wg-quick@wg0.service
+Wants=network-online.target
+Requires=wg-quick@wg0.service
+PartOf=orama-node.service
+
+[Service]
+Type=simple
+ExecStart=%[1]s/bin/vault-guardian --config %[2]s/vault.yaml
+Restart=on-failure
+RestartSec=5
+StandardOutput=append:%[3]s
+StandardError=append:%[3]s
+SyslogIdentifier=orama-vault
+
+PrivateTmp=yes
+ProtectSystem=strict
+ReadWritePaths=%[2]s
+NoNewPrivileges=yes
+LimitMEMLOCK=67108864
+MemoryMax=512M
+TimeoutStopSec=30
+KillMode=mixed
+
+[Install]
+WantedBy=multi-user.target
+`, ssg.oramaHome, dataDir, logFile)
+}
+
 // GenerateGatewayService generates the Orama Gateway systemd unit
 func (ssg *SystemdServiceGenerator) GenerateGatewayService() string {
 	logFile := filepath.Join(ssg.oramaDir, "logs", "gateway.log")
diff --git a/pkg/gateway/gateway.go b/pkg/gateway/gateway.go
index c597343..d7088c3 100644
--- a/pkg/gateway/gateway.go
+++ b/pkg/gateway/gateway.go
@@ -31,6 +31,7 @@ import (
 	serverlesshandlers "github.com/DeBrosOfficial/network/pkg/gateway/handlers/serverless"
 	joinhandlers "github.com/DeBrosOfficial/network/pkg/gateway/handlers/join"
 	webrtchandlers "github.com/DeBrosOfficial/network/pkg/gateway/handlers/webrtc"
+	vaulthandlers "github.com/DeBrosOfficial/network/pkg/gateway/handlers/vault"
 	wireguardhandlers "github.com/DeBrosOfficial/network/pkg/gateway/handlers/wireguard"
 	sqlitehandlers "github.com/DeBrosOfficial/network/pkg/gateway/handlers/sqlite"
 	"github.com/DeBrosOfficial/network/pkg/gateway/handlers/storage"
@@ -162,6 +163,9 @@ type Gateway struct {
 	// Shared HTTP transport for proxy connections (connection pooling)
 	proxyTransport *http.Transport
 
+	// Vault proxy handlers
+	vaultHandlers *vaulthandlers.Handlers
+
 	// Namespace health state (local service probes + hourly reconciliation)
 	nsHealth *namespaceHealthState
 }
@@ -395,6 +399,7 @@ func New(logger *logging.ColoredLogger, cfg *Config) (*Gateway, error) {
 	if deps.ORMClient != nil {
 		gw.wireguardHandler = wireguardhandlers.NewHandler(logger.Logger, deps.ORMClient, cfg.ClusterSecret)
 		gw.joinHandler = joinhandlers.NewHandler(logger.Logger, deps.ORMClient, cfg.DataDir)
+		gw.vaultHandlers = vaulthandlers.NewHandlers(logger, deps.Client)
 	}
 
 	// Initialize deployment system
diff --git a/pkg/gateway/handlers/vault/handlers.go b/pkg/gateway/handlers/vault/handlers.go
new file mode 100644
index 0000000..ec80dcb
--- /dev/null
+++ b/pkg/gateway/handlers/vault/handlers.go
@@ -0,0 +1,132 @@
+// Package vault provides HTTP handlers for vault proxy operations.
+//
+// The gateway acts as a smart proxy between RootWallet clients and
+// vault guardian nodes on the WireGuard overlay network. It handles
+// Shamir split/combine so clients make a single HTTPS call.
+package vault
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/DeBrosOfficial/network/pkg/client"
+	"github.com/DeBrosOfficial/network/pkg/logging"
+)
+
+const (
+	// VaultGuardianPort is the port vault guardians listen on (client API).
+	VaultGuardianPort = 7500
+
+	// guardianTimeout is the per-guardian HTTP request timeout.
+	guardianTimeout = 5 * time.Second
+
+	// overallTimeout is the maximum time for the full fan-out operation.
+	overallTimeout = 15 * time.Second
+
+	// maxPushBodySize limits push request bodies (1 MiB).
+	maxPushBodySize = 1 << 20
+
+	// maxPullBodySize limits pull request bodies (4 KiB).
+	maxPullBodySize = 4 << 10
+)
+
+// Handlers provides HTTP handlers for vault proxy operations.
+type Handlers struct {
+	logger      *logging.ColoredLogger
+	dbClient    client.NetworkClient
+	rateLimiter *IdentityRateLimiter
+	httpClient  *http.Client
+}
+
+// NewHandlers creates vault proxy handlers.
+func NewHandlers(logger *logging.ColoredLogger, dbClient client.NetworkClient) *Handlers {
+	h := &Handlers{
+		logger:   logger,
+		dbClient: dbClient,
+		rateLimiter: NewIdentityRateLimiter(
+			30,  // 30 pushes per hour per identity
+			120, // 120 pulls per hour per identity
+		),
+		httpClient: &http.Client{
+			Timeout: guardianTimeout,
+			Transport: &http.Transport{
+				MaxIdleConns:        100,
+				MaxIdleConnsPerHost: 10,
+				IdleConnTimeout:     90 * time.Second,
+			},
+		},
+	}
+	h.rateLimiter.StartCleanup(10*time.Minute, 1*time.Hour)
+	return h
+}
+
+// guardian represents a reachable vault guardian node.
+type guardian struct {
+	IP   string
+	Port int
+}
+
+// discoverGuardians queries dns_nodes for all active nodes.
+// Every Orama node runs a vault guardian, so every active node is a guardian.
+func (h *Handlers) discoverGuardians(ctx context.Context) ([]guardian, error) {
+	db := h.dbClient.Database()
+	internalCtx := client.WithInternalAuth(ctx)
+
+	query := "SELECT COALESCE(internal_ip, ip_address) FROM dns_nodes WHERE status = 'active'"
+	result, err := db.Query(internalCtx, query)
+	if err != nil {
+		return nil, fmt.Errorf("vault: failed to query guardian nodes: %w", err)
+	}
+	if result == nil || len(result.Rows) == 0 {
+		return nil, fmt.Errorf("vault: no active guardian nodes found")
+	}
+
+	guardians := make([]guardian, 0, len(result.Rows))
+	for _, row := range result.Rows {
+		if len(row) == 0 {
+			continue
+		}
+		ip := getString(row[0])
+		if ip == "" {
+			continue
+		}
+		guardians = append(guardians, guardian{IP: ip, Port: VaultGuardianPort})
+	}
+	if len(guardians) == 0 {
+		return nil, fmt.Errorf("vault: no guardian nodes with valid IPs found")
+	}
+	return guardians, nil
+}
+
+func writeJSON(w http.ResponseWriter, status int, v interface{}) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(v)
+}
+
+func writeError(w http.ResponseWriter, status int, msg string) {
+	writeJSON(w, status, map[string]string{"error": msg})
+}
+
+func getString(v interface{}) string {
+	if s, ok := v.(string); ok {
+		return s
+	}
+	return ""
+}
+
+// isValidIdentity checks that identity is exactly 64 hex characters.
+func isValidIdentity(identity string) bool {
+	if len(identity) != 64 {
+		return false
+	}
+	for _, c := range identity {
+		if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
+			return false
+		}
+	}
+	return true
+}
diff --git a/pkg/gateway/handlers/vault/health_handler.go b/pkg/gateway/handlers/vault/health_handler.go
new file mode 100644
index 0000000..e5dd702
--- /dev/null
+++ b/pkg/gateway/handlers/vault/health_handler.go
@@ -0,0 +1,116 @@
+package vault
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+	"sync/atomic"
+
+	"github.com/DeBrosOfficial/network/pkg/shamir"
+)
+
+// HealthResponse is returned for GET /v1/vault/health.
+type HealthResponse struct {
+	Status string `json:"status"` // "healthy", "degraded", "unavailable"
+}
+
+// StatusResponse is returned for GET /v1/vault/status.
+type StatusResponse struct {
+	Guardians  int `json:"guardians"`   // Total guardian nodes
+	Healthy    int `json:"healthy"`     // Reachable guardians
+	Threshold  int `json:"threshold"`   // Read quorum (K)
+	WriteQuorum int `json:"write_quorum"` // Write quorum (W)
+}
+
+// HandleHealth processes GET /v1/vault/health.
+func (h *Handlers) HandleHealth(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
+		return
+	}
+
+	guardians, err := h.discoverGuardians(r.Context())
+	if err != nil {
+		writeJSON(w, http.StatusOK, HealthResponse{Status: "unavailable"})
+		return
+	}
+
+	n := len(guardians)
+	healthy := h.probeGuardians(r.Context(), guardians)
+
+	k := shamir.AdaptiveThreshold(n)
+	wq := shamir.WriteQuorum(n)
+
+	status := "healthy"
+	if healthy < wq {
+		if healthy >= k {
+			status = "degraded"
+		} else {
+			status = "unavailable"
+		}
+	}
+
+	writeJSON(w, http.StatusOK, HealthResponse{Status: status})
+}
+
+// HandleStatus processes GET /v1/vault/status.
+func (h *Handlers) HandleStatus(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
+		return
+	}
+
+	guardians, err := h.discoverGuardians(r.Context())
+	if err != nil {
+		writeJSON(w, http.StatusOK, StatusResponse{})
+		return
+	}
+
+	n := len(guardians)
+	healthy := h.probeGuardians(r.Context(), guardians)
+
+	writeJSON(w, http.StatusOK, StatusResponse{
+		Guardians:   n,
+		Healthy:     healthy,
+		Threshold:   shamir.AdaptiveThreshold(n),
+		WriteQuorum: shamir.WriteQuorum(n),
+	})
+}
+
+// probeGuardians checks health of all guardians in parallel and returns the healthy count.
+func (h *Handlers) probeGuardians(ctx context.Context, guardians []guardian) int {
+	ctx, cancel := context.WithTimeout(ctx, guardianTimeout)
+	defer cancel()
+
+	var healthyCount atomic.Int32
+	var wg sync.WaitGroup
+	wg.Add(len(guardians))
+
+	for _, g := range guardians {
+		go func(gd guardian) {
+			defer wg.Done()
+
+			url := fmt.Sprintf("http://%s:%d/v1/vault/health", gd.IP, gd.Port)
+			req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+			if err != nil {
+				return
+			}
+
+			resp, err := h.httpClient.Do(req)
+			if err != nil {
+				return
+			}
+			defer resp.Body.Close()
+			io.Copy(io.Discard, resp.Body)
+
+			if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+				healthyCount.Add(1)
+			}
+		}(g)
+	}
+
+	wg.Wait()
+	return int(healthyCount.Load())
+}
diff --git a/pkg/gateway/handlers/vault/pull_handler.go b/pkg/gateway/handlers/vault/pull_handler.go
new file mode 100644
index 0000000..2164487
--- /dev/null
+++ b/pkg/gateway/handlers/vault/pull_handler.go
@@ -0,0 +1,183 @@
+package vault
+
+import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+
+	"github.com/DeBrosOfficial/network/pkg/logging"
+	"github.com/DeBrosOfficial/network/pkg/shamir"
+	"go.uber.org/zap"
+)
+
+// PullRequest is the client-facing request body.
+type PullRequest struct {
+	Identity string `json:"identity"` // 64 hex chars
+}
+
+// PullResponse is returned to the client.
+type PullResponse struct {
+	Envelope  string `json:"envelope"`  // base64-encoded reconstructed envelope
+	Collected int    `json:"collected"` // Number of shares collected
+	Threshold int    `json:"threshold"` // K threshold used
+}
+
+// guardianPullRequest is sent to each vault guardian.
+type guardianPullRequest struct {
+	Identity string `json:"identity"`
+}
+
+// guardianPullResponse is the response from a guardian.
+type guardianPullResponse struct {
+	Share string `json:"share"` // base64([x:1byte][y:rest])
+}
+
+// HandlePull processes POST /v1/vault/pull.
+func (h *Handlers) HandlePull(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
+		return
+	}
+
+	body, err := io.ReadAll(io.LimitReader(r.Body, maxPullBodySize))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "failed to read request body")
+		return
+	}
+
+	var req PullRequest
+	if err := json.Unmarshal(body, &req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid JSON")
+		return
+	}
+
+	if !isValidIdentity(req.Identity) {
+		writeError(w, http.StatusBadRequest, "identity must be 64 hex characters")
+		return
+	}
+
+	if !h.rateLimiter.AllowPull(req.Identity) {
+		w.Header().Set("Retry-After", "30")
+		writeError(w, http.StatusTooManyRequests, "pull rate limit exceeded for this identity")
+		return
+	}
+
+	guardians, err := h.discoverGuardians(r.Context())
+	if err != nil {
+		h.logger.ComponentError(logging.ComponentGeneral, "Vault pull: guardian discovery failed", zap.Error(err))
+		writeError(w, http.StatusServiceUnavailable, "no guardian nodes available")
+		return
+	}
+
+	n := len(guardians)
+	k := shamir.AdaptiveThreshold(n)
+
+	// Fan out pull requests to all guardians.
+	ctx, cancel := context.WithTimeout(r.Context(), overallTimeout)
+	defer cancel()
+
+	type shareResult struct {
+		share shamir.Share
+		ok    bool
+	}
+
+	results := make([]shareResult, n)
+	var wg sync.WaitGroup
+	wg.Add(n)
+
+	for i, g := range guardians {
+		go func(idx int, gd guardian) {
+			defer wg.Done()
+
+			guardianReq := guardianPullRequest{Identity: req.Identity}
+			reqBody, _ := json.Marshal(guardianReq)
+
+			url := fmt.Sprintf("http://%s:%d/v1/vault/pull", gd.IP, gd.Port)
+			httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(reqBody))
+			if err != nil {
+				return
+			}
+			httpReq.Header.Set("Content-Type", "application/json")
+
+			resp, err := h.httpClient.Do(httpReq)
+			if err != nil {
+				return
+			}
+			defer resp.Body.Close()
+
+			if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+				io.Copy(io.Discard, resp.Body)
+				return
+			}
+
+			var pullResp guardianPullResponse
+			if err := json.NewDecoder(resp.Body).Decode(&pullResp); err != nil {
+				return
+			}
+
+			shareBytes, err := base64.StdEncoding.DecodeString(pullResp.Share)
+			if err != nil || len(shareBytes) < 2 {
+				return
+			}
+
+			results[idx] = shareResult{
+				share: shamir.Share{
+					X: shareBytes[0],
+					Y: shareBytes[1:],
+				},
+				ok: true,
+			}
+		}(i, g)
+	}
+
+	wg.Wait()
+
+	// Collect successful shares.
+	shares := make([]shamir.Share, 0, n)
+	for _, r := range results {
+		if r.ok {
+			shares = append(shares, r.share)
+		}
+	}
+
+	if len(shares) < k {
+		h.logger.ComponentError(logging.ComponentGeneral, "Vault pull: not enough shares",
+			zap.Int("collected", len(shares)), zap.Int("total", n), zap.Int("threshold", k))
+		writeError(w, http.StatusServiceUnavailable,
+			fmt.Sprintf("not enough shares: collected %d of %d required (contacted %d guardians)", len(shares), k, n))
+		return
+	}
+
+	// Shamir combine to reconstruct envelope.
+	envelope, err := shamir.Combine(shares[:k])
+	if err != nil {
+		h.logger.ComponentError(logging.ComponentGeneral, "Vault pull: Shamir combine failed", zap.Error(err))
+		writeError(w, http.StatusInternalServerError, "failed to reconstruct envelope")
+		return
+	}
+
+	// Wipe collected shares.
+	for i := range shares {
+		for j := range shares[i].Y {
+			shares[i].Y[j] = 0
+		}
+	}
+
+	envelopeB64 := base64.StdEncoding.EncodeToString(envelope)
+
+	// Wipe envelope.
+	for i := range envelope {
+		envelope[i] = 0
+	}
+
+	writeJSON(w, http.StatusOK, PullResponse{
+		Envelope:  envelopeB64,
+		Collected: len(shares),
+		Threshold: k,
+	})
+}
diff --git a/pkg/gateway/handlers/vault/push_handler.go b/pkg/gateway/handlers/vault/push_handler.go
new file mode 100644
index 0000000..b3e729d
--- /dev/null
+++ b/pkg/gateway/handlers/vault/push_handler.go
@@ -0,0 +1,168 @@
+package vault
+
+import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+	"sync/atomic"
+
+	"github.com/DeBrosOfficial/network/pkg/logging"
+	"github.com/DeBrosOfficial/network/pkg/shamir"
+	"go.uber.org/zap"
+)
+
+// PushRequest is the client-facing request body.
+type PushRequest struct {
+	Identity string `json:"identity"` // 64 hex chars (SHA-256)
+	Envelope string `json:"envelope"` // base64-encoded encrypted envelope
+	Version  uint64 `json:"version"`  // Anti-rollback version counter
+}
+
+// PushResponse is returned to the client.
+type PushResponse struct {
+	Status    string `json:"status"`    // "ok" or "partial"
+	AckCount  int    `json:"ack_count"`
+	Total     int    `json:"total"`
+	Quorum    int    `json:"quorum"`
+	Threshold int    `json:"threshold"`
+}
+
+// guardianPushRequest is sent to each vault guardian.
+type guardianPushRequest struct {
+	Identity string `json:"identity"`
+	Share    string `json:"share"`   // base64([x:1byte][y:rest])
+	Version  uint64 `json:"version"`
+}
+
+// HandlePush processes POST /v1/vault/push.
+func (h *Handlers) HandlePush(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		writeError(w, http.StatusMethodNotAllowed, "method not allowed")
+		return
+	}
+
+	body, err := io.ReadAll(io.LimitReader(r.Body, maxPushBodySize))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "failed to read request body")
+		return
+	}
+
+	var req PushRequest
+	if err := json.Unmarshal(body, &req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid JSON")
+		return
+	}
+
+	if !isValidIdentity(req.Identity) {
+		writeError(w, http.StatusBadRequest, "identity must be 64 hex characters")
+		return
+	}
+
+	envelopeBytes, err := base64.StdEncoding.DecodeString(req.Envelope)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid base64 envelope")
+		return
+	}
+	if len(envelopeBytes) == 0 {
+		writeError(w, http.StatusBadRequest, "envelope must not be empty")
+		return
+	}
+
+	if !h.rateLimiter.AllowPush(req.Identity) {
+		w.Header().Set("Retry-After", "120")
+		writeError(w, http.StatusTooManyRequests, "push rate limit exceeded for this identity")
+		return
+	}
+
+	guardians, err := h.discoverGuardians(r.Context())
+	if err != nil {
+		h.logger.ComponentError(logging.ComponentGeneral, "Vault push: guardian discovery failed", zap.Error(err))
+		writeError(w, http.StatusServiceUnavailable, "no guardian nodes available")
+		return
+	}
+
+	n := len(guardians)
+	k := shamir.AdaptiveThreshold(n)
+	quorum := shamir.WriteQuorum(n)
+
+	shares, err := shamir.Split(envelopeBytes, n, k)
+	if err != nil {
+		h.logger.ComponentError(logging.ComponentGeneral, "Vault push: Shamir split failed", zap.Error(err))
+		writeError(w, http.StatusInternalServerError, "failed to split envelope")
+		return
+	}
+
+	// Fan out to guardians in parallel.
+	ctx, cancel := context.WithTimeout(r.Context(), overallTimeout)
+	defer cancel()
+
+	var ackCount atomic.Int32
+	var wg sync.WaitGroup
+	wg.Add(n)
+
+	for i, g := range guardians {
+		go func(idx int, gd guardian) {
+			defer wg.Done()
+
+			share := shares[idx]
+			// Serialize: [x:1byte][y:rest]
+			shareBytes := make([]byte, 1+len(share.Y))
+			shareBytes[0] = share.X
+			copy(shareBytes[1:], share.Y)
+			shareB64 := base64.StdEncoding.EncodeToString(shareBytes)
+
+			guardianReq := guardianPushRequest{
+				Identity: req.Identity,
+				Share:    shareB64,
+				Version:  req.Version,
+			}
+			reqBody, _ := json.Marshal(guardianReq)
+
+			url := fmt.Sprintf("http://%s:%d/v1/vault/push", gd.IP, gd.Port)
+			httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(reqBody))
+			if err != nil {
+				return
+			}
+			httpReq.Header.Set("Content-Type", "application/json")
+
+			resp, err := h.httpClient.Do(httpReq)
+			if err != nil {
+				return
+			}
+			defer resp.Body.Close()
+			io.Copy(io.Discard, resp.Body)
+
+			if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+				ackCount.Add(1)
+			}
+		}(i, g)
+	}
+
+	wg.Wait()
+
+	// Wipe share data.
+	for i := range shares {
+		for j := range shares[i].Y {
+			shares[i].Y[j] = 0
+		}
+	}
+
+	ack := int(ackCount.Load())
+	status := "ok"
+	if ack < quorum {
+		status = "partial"
+	}
+
+	writeJSON(w, http.StatusOK, PushResponse{
+		Status:    status,
+		AckCount:  ack,
+		Total:     n,
+		Quorum:    quorum,
+		Threshold: k,
+	})
+}
diff --git a/pkg/gateway/handlers/vault/rate_limiter.go b/pkg/gateway/handlers/vault/rate_limiter.go
new file mode 100644
index 0000000..9a69821
--- /dev/null
+++ b/pkg/gateway/handlers/vault/rate_limiter.go
@@ -0,0 +1,120 @@
+package vault
+
+import (
+	"sync"
+	"time"
+)
+
+// IdentityRateLimiter provides per-identity-hash rate limiting for vault operations.
+// Push and pull have separate rate limits since push is more expensive.
+type IdentityRateLimiter struct {
+	pushBuckets sync.Map // identity -> *tokenBucket
+	pullBuckets sync.Map // identity -> *tokenBucket
+	pushRate    float64  // tokens per second
+	pushBurst   int
+	pullRate    float64  // tokens per second
+	pullBurst   int
+	stopCh      chan struct{}
+}
+
+type tokenBucket struct {
+	mu        sync.Mutex
+	tokens    float64
+	lastCheck time.Time
+}
+
+// NewIdentityRateLimiter creates a per-identity rate limiter.
+// pushPerHour and pullPerHour are sustained rates; burst is 1/6th of the hourly rate.
+func NewIdentityRateLimiter(pushPerHour, pullPerHour int) *IdentityRateLimiter {
+	pushBurst := pushPerHour / 6
+	if pushBurst < 1 {
+		pushBurst = 1
+	}
+	pullBurst := pullPerHour / 6
+	if pullBurst < 1 {
+		pullBurst = 1
+	}
+	return &IdentityRateLimiter{
+		pushRate:  float64(pushPerHour) / 3600.0,
+		pushBurst: pushBurst,
+		pullRate:  float64(pullPerHour) / 3600.0,
+		pullBurst: pullBurst,
+	}
+}
+
+// AllowPush checks if a push for this identity is allowed.
+func (rl *IdentityRateLimiter) AllowPush(identity string) bool {
+	return rl.allow(&rl.pushBuckets, identity, rl.pushRate, rl.pushBurst)
+}
+
+// AllowPull checks if a pull for this identity is allowed.
+func (rl *IdentityRateLimiter) AllowPull(identity string) bool {
+	return rl.allow(&rl.pullBuckets, identity, rl.pullRate, rl.pullBurst)
+}
+
+func (rl *IdentityRateLimiter) allow(buckets *sync.Map, identity string, rate float64, burst int) bool {
+	val, _ := buckets.LoadOrStore(identity, &tokenBucket{
+		tokens:    float64(burst),
+		lastCheck: time.Now(),
+	})
+	b := val.(*tokenBucket)
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	now := time.Now()
+	elapsed := now.Sub(b.lastCheck).Seconds()
+	b.tokens += elapsed * rate
+	if b.tokens > float64(burst) {
+		b.tokens = float64(burst)
+	}
+	b.lastCheck = now
+
+	if b.tokens >= 1 {
+		b.tokens--
+		return true
+	}
+	return false
+}
+
+// StartCleanup runs periodic cleanup of stale identity entries.
+func (rl *IdentityRateLimiter) StartCleanup(interval, maxAge time.Duration) {
+	rl.stopCh = make(chan struct{})
+	go func() {
+		ticker := time.NewTicker(interval)
+		defer ticker.Stop()
+		for {
+			select {
+			case <-ticker.C:
+				rl.cleanup(maxAge)
+			case <-rl.stopCh:
+				return
+			}
+		}
+	}()
+}
+
+// Stop terminates the background cleanup goroutine.
+func (rl *IdentityRateLimiter) Stop() {
+	if rl.stopCh != nil {
+		close(rl.stopCh)
+	}
+}
+
+func (rl *IdentityRateLimiter) cleanup(maxAge time.Duration) {
+	cutoff := time.Now().Add(-maxAge)
+	cleanMap := func(m *sync.Map) {
+		m.Range(func(key, value interface{}) bool {
+			b := value.(*tokenBucket)
+			b.mu.Lock()
+			stale := b.lastCheck.Before(cutoff)
+			b.mu.Unlock()
+			if stale {
+				m.Delete(key)
+			}
+			return true
+		})
+	}
+	cleanMap(&rl.pushBuckets)
+	cleanMap(&rl.pullBuckets)
+}
diff --git a/pkg/gateway/middleware.go b/pkg/gateway/middleware.go
index 8e25840..65567ae 100644
--- a/pkg/gateway/middleware.go
+++ b/pkg/gateway/middleware.go
@@ -417,6 +417,11 @@ func isPublicPath(p string) bool {
 		return true
 	}
 
+	// Vault proxy endpoints (no auth — rate-limited per identity hash within handler)
+	if strings.HasPrefix(p, "/v1/vault/") {
+		return true
+	}
+
 	// Phantom auth endpoints are public (session creation, status polling, completion)
 	if strings.HasPrefix(p, "/v1/auth/phantom/") {
 		return true
diff --git a/pkg/gateway/routes.go b/pkg/gateway/routes.go
index 4e49910..a791eda 100644
--- a/pkg/gateway/routes.go
+++ b/pkg/gateway/routes.go
@@ -114,6 +114,14 @@ func (g *Gateway) Routes() http.Handler {
 		mux.HandleFunc("/v1/pubsub/presence", g.pubsubHandlers.PresenceHandler)
 	}
 
+	// vault proxy (public, rate-limited per identity within handler)
+	if g.vaultHandlers != nil {
+		mux.HandleFunc("/v1/vault/push", g.vaultHandlers.HandlePush)
+		mux.HandleFunc("/v1/vault/pull", g.vaultHandlers.HandlePull)
+		mux.HandleFunc("/v1/vault/health", g.vaultHandlers.HandleHealth)
+		mux.HandleFunc("/v1/vault/status", g.vaultHandlers.HandleStatus)
+	}
+
 	// webrtc
 	if g.webrtcHandlers != nil {
 		mux.HandleFunc("/v1/webrtc/turn/credentials", g.webrtcHandlers.CredentialsHandler)
diff --git a/pkg/shamir/field.go b/pkg/shamir/field.go
new file mode 100644
index 0000000..2dd4d97
--- /dev/null
+++ b/pkg/shamir/field.go
@@ -0,0 +1,82 @@
+// Package shamir implements Shamir's Secret Sharing over GF(2^8).
+//
+// Uses the AES irreducible polynomial x^8 + x^4 + x^3 + x + 1 (0x11B)
+// with generator 3. Precomputed log/exp tables for O(1) field arithmetic.
+//
+// Cross-platform compatible with the Zig (orama-vault) and TypeScript
+// (network-ts-sdk) implementations using identical field parameters.
+package shamir
+
+import "errors"
+
+// ErrDivisionByZero is returned when dividing by zero in GF(2^8).
+var ErrDivisionByZero = errors.New("shamir: division by zero in GF(2^8)")
+
+// Irreducible polynomial: x^8 + x^4 + x^3 + x + 1.
+const irreducible = 0x11B
+
+// expTable[i] = generator^i mod polynomial, for i in 0..511.
+// Extended to 512 entries so Mul can use (logA + logB) without modular reduction.
+var expTable [512]byte
+
+// logTable[a] = i where generator^i = a, for a in 1..255.
+// logTable[0] is unused (log of zero is undefined).
+var logTable [256]byte
+
+func init() {
+	x := uint16(1)
+	for i := 0; i < 512; i++ {
+		if i < 256 {
+			expTable[i] = byte(x)
+			logTable[byte(x)] = byte(i)
+		} else {
+			expTable[i] = expTable[i-255]
+		}
+
+		if i < 255 {
+			// Multiply by generator (3): x*3 = x*2 XOR x
+			x2 := x << 1
+			x3 := x2 ^ x
+			if x3&0x100 != 0 {
+				x3 ^= irreducible
+			}
+			x = x3
+		}
+	}
+}
+
+// Add returns a XOR b (addition in GF(2^8)).
+func Add(a, b byte) byte {
+	return a ^ b
+}
+
+// Mul returns a * b in GF(2^8) via log/exp tables.
+func Mul(a, b byte) byte {
+	if a == 0 || b == 0 {
+		return 0
+	}
+	logSum := uint16(logTable[a]) + uint16(logTable[b])
+	return expTable[logSum]
+}
+
+// Inv returns the multiplicative inverse of a in GF(2^8).
+// Returns ErrDivisionByZero if a == 0.
+func Inv(a byte) (byte, error) {
+	if a == 0 {
+		return 0, ErrDivisionByZero
+	}
+	return expTable[255-uint16(logTable[a])], nil
+}
+
+// Div returns a / b in GF(2^8).
+// Returns ErrDivisionByZero if b == 0.
+func Div(a, b byte) (byte, error) {
+	if b == 0 {
+		return 0, ErrDivisionByZero
+	}
+	if a == 0 {
+		return 0, nil
+	}
+	logDiff := uint16(logTable[a]) + 255 - uint16(logTable[b])
+	return expTable[logDiff], nil
+}
diff --git a/pkg/shamir/shamir.go b/pkg/shamir/shamir.go
new file mode 100644
index 0000000..0ba260a
--- /dev/null
+++ b/pkg/shamir/shamir.go
@@ -0,0 +1,150 @@
+package shamir
+
+import (
+	"crypto/rand"
+	"errors"
+	"fmt"
+)
+
+var (
+	ErrThresholdTooSmall   = errors.New("shamir: threshold K must be at least 2")
+	ErrShareCountTooSmall  = errors.New("shamir: share count N must be >= threshold K")
+	ErrTooManyShares       = errors.New("shamir: maximum 255 shares (GF(2^8) limit)")
+	ErrEmptySecret         = errors.New("shamir: secret must not be empty")
+	ErrNotEnoughShares     = errors.New("shamir: need at least 2 shares to reconstruct")
+	ErrMismatchedShareLen  = errors.New("shamir: all shares must have the same data length")
+	ErrZeroShareIndex      = errors.New("shamir: share index must not be 0")
+	ErrDuplicateShareIndex = errors.New("shamir: duplicate share indices")
+)
+
+// Share represents a single Shamir share.
+type Share struct {
+	X byte   // Evaluation point (1..255, never 0)
+	Y []byte // Share data (same length as original secret)
+}
+
+// Split divides secret into n shares with threshold k.
+// Any k shares can reconstruct the secret; k-1 reveal nothing.
+func Split(secret []byte, n, k int) ([]Share, error) {
+	if k < 2 {
+		return nil, ErrThresholdTooSmall
+	}
+	if n < k {
+		return nil, ErrShareCountTooSmall
+	}
+	if n > 255 {
+		return nil, ErrTooManyShares
+	}
+	if len(secret) == 0 {
+		return nil, ErrEmptySecret
+	}
+
+	shares := make([]Share, n)
+	for i := range shares {
+		shares[i] = Share{
+			X: byte(i + 1),
+			Y: make([]byte, len(secret)),
+		}
+	}
+
+	// Temporary buffer for polynomial coefficients.
+	coeffs := make([]byte, k)
+	defer func() {
+		for i := range coeffs {
+			coeffs[i] = 0
+		}
+	}()
+
+	for byteIdx := 0; byteIdx < len(secret); byteIdx++ {
+		coeffs[0] = secret[byteIdx]
+		// Fill degrees 1..k-1 with random bytes.
+		if _, err := rand.Read(coeffs[1:]); err != nil {
+			return nil, fmt.Errorf("shamir: random generation failed: %w", err)
+		}
+		for i := range shares {
+			shares[i].Y[byteIdx] = evaluatePolynomial(coeffs, shares[i].X)
+		}
+	}
+
+	return shares, nil
+}
+
+// Combine reconstructs the secret from k or more shares via Lagrange interpolation.
+func Combine(shares []Share) ([]byte, error) {
+	if len(shares) < 2 {
+		return nil, ErrNotEnoughShares
+	}
+
+	secretLen := len(shares[0].Y)
+	seen := make(map[byte]bool, len(shares))
+	for _, s := range shares {
+		if s.X == 0 {
+			return nil, ErrZeroShareIndex
+		}
+		if len(s.Y) != secretLen {
+			return nil, ErrMismatchedShareLen
+		}
+		if seen[s.X] {
+			return nil, ErrDuplicateShareIndex
+		}
+		seen[s.X] = true
+	}
+
+	result := make([]byte, secretLen)
+	for byteIdx := 0; byteIdx < secretLen; byteIdx++ {
+		var value byte
+		for i, si := range shares {
+			// Lagrange basis polynomial L_i evaluated at 0:
+			// L_i(0) = product over j!=i of (0 - x_j)/(x_i - x_j)
+			//         = product over j!=i of x_j / (x_i XOR x_j)
+			var basis byte = 1
+			for j, sj := range shares {
+				if i == j {
+					continue
+				}
+				num := sj.X
+				den := Add(si.X, sj.X) // x_i - x_j = x_i XOR x_j in GF(2^8)
+				d, err := Div(num, den)
+				if err != nil {
+					return nil, err
+				}
+				basis = Mul(basis, d)
+			}
+			value = Add(value, Mul(si.Y[byteIdx], basis))
+		}
+		result[byteIdx] = value
+	}
+
+	return result, nil
+}
+
+// AdaptiveThreshold returns max(3, floor(n/3)).
+// This is the read quorum: minimum shares needed to reconstruct.
+func AdaptiveThreshold(n int) int {
+	t := n / 3
+	if t < 3 {
+		return 3
+	}
+	return t
+}
+
+// WriteQuorum returns ceil(2n/3).
+// This is the write quorum: minimum ACKs needed for a successful push.
+func WriteQuorum(n int) int {
+	if n == 0 {
+		return 0
+	}
+	if n <= 2 {
+		return n
+	}
+	return (2*n + 2) / 3
+}
+
+// evaluatePolynomial evaluates p(x) = coeffs[0] + coeffs[1]*x + ... using Horner's method.
+func evaluatePolynomial(coeffs []byte, x byte) byte {
+	var result byte
+	for i := len(coeffs) - 1; i >= 0; i-- {
+		result = Add(Mul(result, x), coeffs[i])
+	}
+	return result
+}
diff --git a/pkg/shamir/shamir_test.go b/pkg/shamir/shamir_test.go
new file mode 100644
index 0000000..2e57cc9
--- /dev/null
+++ b/pkg/shamir/shamir_test.go
@@ -0,0 +1,501 @@
+package shamir
+
+import (
+	"testing"
+)
+
+// ── GF(2^8) Field Tests ────────────────────────────────────────────────────
+
+func TestExpTable_Cycle(t *testing.T) {
+	// g^0 = 1, g^255 = 1 (cyclic group of order 255)
+	if expTable[0] != 1 {
+		t.Errorf("exp[0] = %d, want 1", expTable[0])
+	}
+	if expTable[255] != 1 {
+		t.Errorf("exp[255] = %d, want 1", expTable[255])
+	}
+}
+
+func TestExpTable_AllNonzeroAppear(t *testing.T) {
+	var seen [256]bool
+	for i := 0; i < 255; i++ {
+		v := expTable[i]
+		if seen[v] {
+			t.Fatalf("duplicate value %d at index %d", v, i)
+		}
+		seen[v] = true
+	}
+	for v := 1; v < 256; v++ {
+		if !seen[v] {
+			t.Errorf("value %d not seen in exp[0..255]", v)
+		}
+	}
+	if seen[0] {
+		t.Error("zero should not appear in exp[0..254]")
+	}
+}
+
+// Cross-platform test vectors from orama-vault/src/sss/test_cross_platform.zig
+func TestExpTable_CrossPlatform(t *testing.T) {
+	vectors := [][2]int{
+		{0, 1}, {10, 114}, {20, 216}, {30, 102},
+		{40, 106}, {50, 4}, {60, 211}, {70, 77},
+		{80, 131}, {90, 179}, {100, 16}, {110, 97},
+		{120, 47}, {130, 58}, {140, 250}, {150, 64},
+		{160, 159}, {170, 188}, {180, 232}, {190, 197},
+		{200, 27}, {210, 74}, {220, 198}, {230, 141},
+		{240, 57}, {250, 108}, {254, 246}, {255, 1},
+	}
+	for _, v := range vectors {
+		if got := expTable[v[0]]; got != byte(v[1]) {
+			t.Errorf("exp[%d] = %d, want %d", v[0], got, v[1])
+		}
+	}
+}
+
+func TestMul_CrossPlatform(t *testing.T) {
+	vectors := [][3]byte{
+		{1, 1, 1}, {1, 2, 2}, {1, 3, 3},
+		{1, 42, 42}, {1, 127, 127}, {1, 170, 170}, {1, 255, 255},
+		{2, 1, 2}, {2, 2, 4}, {2, 3, 6},
+		{2, 42, 84}, {2, 127, 254}, {2, 170, 79}, {2, 255, 229},
+		{3, 1, 3}, {3, 2, 6}, {3, 3, 5},
+		{3, 42, 126}, {3, 127, 129}, {3, 170, 229}, {3, 255, 26},
+		{42, 1, 42}, {42, 2, 84}, {42, 3, 126},
+		{42, 42, 40}, {42, 127, 82}, {42, 170, 244}, {42, 255, 142},
+		{127, 1, 127}, {127, 2, 254}, {127, 3, 129},
+		{127, 42, 82}, {127, 127, 137}, {127, 170, 173}, {127, 255, 118},
+		{170, 1, 170}, {170, 2, 79}, {170, 3, 229},
+		{170, 42, 244}, {170, 127, 173}, {170, 170, 178}, {170, 255, 235},
+		{255, 1, 255}, {255, 2, 229}, {255, 3, 26},
+		{255, 42, 142}, {255, 127, 118}, {255, 170, 235}, {255, 255, 19},
+	}
+	for _, v := range vectors {
+		if got := Mul(v[0], v[1]); got != v[2] {
+			t.Errorf("Mul(%d, %d) = %d, want %d", v[0], v[1], got, v[2])
+		}
+	}
+}
+
+func TestMul_Zero(t *testing.T) {
+	for a := 0; a < 256; a++ {
+		if Mul(byte(a), 0) != 0 {
+			t.Errorf("Mul(%d, 0) != 0", a)
+		}
+		if Mul(0, byte(a)) != 0 {
+			t.Errorf("Mul(0, %d) != 0", a)
+		}
+	}
+}
+
+func TestMul_Identity(t *testing.T) {
+	for a := 0; a < 256; a++ {
+		if Mul(byte(a), 1) != byte(a) {
+			t.Errorf("Mul(%d, 1) = %d", a, Mul(byte(a), 1))
+		}
+	}
+}
+
+func TestMul_Commutative(t *testing.T) {
+	for a := 1; a < 256; a += 7 {
+		for b := 1; b < 256; b += 11 {
+			ab := Mul(byte(a), byte(b))
+			ba := Mul(byte(b), byte(a))
+			if ab != ba {
+				t.Errorf("Mul(%d,%d)=%d != Mul(%d,%d)=%d", a, b, ab, b, a, ba)
+			}
+		}
+	}
+}
+
+func TestInv_CrossPlatform(t *testing.T) {
+	vectors := [][2]byte{
+		{1, 1}, {2, 141}, {3, 246}, {5, 82},
+		{7, 209}, {16, 116}, {42, 152}, {127, 130},
+		{128, 131}, {170, 18}, {200, 169}, {255, 28},
+	}
+	for _, v := range vectors {
+		got, err := Inv(v[0])
+		if err != nil {
+			t.Errorf("Inv(%d) returned error: %v", v[0], err)
+			continue
+		}
+		if got != v[1] {
+			t.Errorf("Inv(%d) = %d, want %d", v[0], got, v[1])
+		}
+	}
+}
+
+func TestInv_SelfInverse(t *testing.T) {
+	for a := 1; a < 256; a++ {
+		inv1, _ := Inv(byte(a))
+		inv2, _ := Inv(inv1)
+		if inv2 != byte(a) {
+			t.Errorf("Inv(Inv(%d)) = %d, want %d", a, inv2, a)
+		}
+	}
+}
+
+func TestInv_Product(t *testing.T) {
+	for a := 1; a < 256; a++ {
+		inv1, _ := Inv(byte(a))
+		if Mul(byte(a), inv1) != 1 {
+			t.Errorf("Mul(%d, Inv(%d)) != 1", a, a)
+		}
+	}
+}
+
+func TestInv_Zero(t *testing.T) {
+	_, err := Inv(0)
+	if err != ErrDivisionByZero {
+		t.Errorf("Inv(0) should return ErrDivisionByZero, got %v", err)
+	}
+}
+
+func TestDiv_CrossPlatform(t *testing.T) {
+	vectors := [][3]byte{
+		{1, 1, 1}, {1, 2, 141}, {1, 3, 246},
+		{1, 42, 152}, {1, 127, 130}, {1, 170, 18}, {1, 255, 28},
+		{2, 1, 2}, {2, 2, 1}, {2, 3, 247},
+		{3, 1, 3}, {3, 2, 140}, {3, 3, 1},
+		{42, 1, 42}, {42, 2, 21}, {42, 42, 1},
+		{127, 1, 127}, {127, 127, 1},
+		{170, 1, 170}, {170, 170, 1},
+		{255, 1, 255}, {255, 255, 1},
+	}
+	for _, v := range vectors {
+		got, err := Div(v[0], v[1])
+		if err != nil {
+			t.Errorf("Div(%d, %d) returned error: %v", v[0], v[1], err)
+			continue
+		}
+		if got != v[2] {
+			t.Errorf("Div(%d, %d) = %d, want %d", v[0], v[1], got, v[2])
+		}
+	}
+}
+
+func TestDiv_ByZero(t *testing.T) {
+	_, err := Div(42, 0)
+	if err != ErrDivisionByZero {
+		t.Errorf("Div(42, 0) should return ErrDivisionByZero, got %v", err)
+	}
+}
+
+// ── Polynomial evaluation ──────────────────────────────────────────────────
+
+func TestEvaluatePolynomial_CrossPlatform(t *testing.T) {
+	// p(x) = 42 + 5x + 7x^2
+	coeffs0 := []byte{42, 5, 7}
+	vectors0 := [][2]byte{
+		{1, 40}, {2, 60}, {3, 62}, {4, 78},
+		{5, 76}, {10, 207}, {100, 214}, {255, 125},
+	}
+	for _, v := range vectors0 {
+		if got := evaluatePolynomial(coeffs0, v[0]); got != v[1] {
+			t.Errorf("p(%d) = %d, want %d [coeffs: 42,5,7]", v[0], got, v[1])
+		}
+	}
+
+	// p(x) = 0 + 0xAB*x + 0xCD*x^2
+	coeffs1 := []byte{0, 0xAB, 0xCD}
+	vectors1 := [][2]byte{
+		{1, 102}, {3, 50}, {5, 152}, {7, 204}, {200, 96},
+	}
+	for _, v := range vectors1 {
+		if got := evaluatePolynomial(coeffs1, v[0]); got != v[1] {
+			t.Errorf("p(%d) = %d, want %d [coeffs: 0,AB,CD]", v[0], got, v[1])
+		}
+	}
+
+	// p(x) = 0xFF (constant)
+	coeffs2 := []byte{0xFF}
+	for _, x := range []byte{1, 2, 255} {
+		if got := evaluatePolynomial(coeffs2, x); got != 0xFF {
+			t.Errorf("constant p(%d) = %d, want 255", x, got)
+		}
+	}
+
+	// p(x) = 128 + 64x + 32x^2 + 16x^3
+	coeffs3 := []byte{128, 64, 32, 16}
+	vectors3 := [][2]byte{
+		{1, 240}, {2, 0}, {3, 16}, {4, 193}, {5, 234},
+	}
+	for _, v := range vectors3 {
+		if got := evaluatePolynomial(coeffs3, v[0]); got != v[1] {
+			t.Errorf("p(%d) = %d, want %d [coeffs: 128,64,32,16]", v[0], got, v[1])
+		}
+	}
+}
+
+// ── Lagrange combine (cross-platform) ─────────────────────────────────────
+
+func TestCombine_CrossPlatform_SingleByte(t *testing.T) {
+	// p(x) = 42 + 5x + 7x^2, secret = 42
+	// Shares: (1,40) (2,60) (3,62) (4,78) (5,76)
+	allShares := []Share{
+		{X: 1, Y: []byte{40}},
+		{X: 2, Y: []byte{60}},
+		{X: 3, Y: []byte{62}},
+		{X: 4, Y: []byte{78}},
+		{X: 5, Y: []byte{76}},
+	}
+
+	subsets := [][]int{
+		{0, 1, 2}, // {1,2,3}
+		{0, 2, 4}, // {1,3,5}
+		{1, 3, 4}, // {2,4,5}
+		{2, 3, 4}, // {3,4,5}
+	}
+
+	for _, subset := range subsets {
+		shares := make([]Share, len(subset))
+		for i, idx := range subset {
+			shares[i] = allShares[idx]
+		}
+		result, err := Combine(shares)
+		if err != nil {
+			t.Fatalf("Combine failed for subset %v: %v", subset, err)
+		}
+		if result[0] != 42 {
+			t.Errorf("Combine(subset %v) = %d, want 42", subset, result[0])
+		}
+	}
+}
+
+func TestCombine_CrossPlatform_MultiByte(t *testing.T) {
+	// 2-byte secret [42, 0]
+	// byte0: 42 + 5x + 7x^2 → shares at x=1,3,5: 40, 62, 76
+	// byte1: 0 + 0xAB*x + 0xCD*x^2 → shares at x=1,3,5: 102, 50, 152
+	shares := []Share{
+		{X: 1, Y: []byte{40, 102}},
+		{X: 3, Y: []byte{62, 50}},
+		{X: 5, Y: []byte{76, 152}},
+	}
+	result, err := Combine(shares)
+	if err != nil {
+		t.Fatalf("Combine failed: %v", err)
+	}
+	if result[0] != 42 || result[1] != 0 {
+		t.Errorf("Combine = %v, want [42, 0]", result)
+	}
+}
+
+// ── Split/Combine round-trip ──────────────────────────────────────────────
+
+func TestSplitCombine_RoundTrip_2of3(t *testing.T) {
+	secret := []byte("hello world")
+	shares, err := Split(secret, 3, 2)
+	if err != nil {
+		t.Fatalf("Split: %v", err)
+	}
+	if len(shares) != 3 {
+		t.Fatalf("got %d shares, want 3", len(shares))
+	}
+
+	// Any 2 shares should reconstruct
+	for i := 0; i < 3; i++ {
+		for j := i + 1; j < 3; j++ {
+			result, err := Combine([]Share{shares[i], shares[j]})
+			if err != nil {
+				t.Fatalf("Combine(%d,%d): %v", i, j, err)
+			}
+			if string(result) != string(secret) {
+				t.Errorf("Combine(%d,%d) = %q, want %q", i, j, result, secret)
+			}
+		}
+	}
+}
+
+func TestSplitCombine_RoundTrip_3of5(t *testing.T) {
+	secret := []byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
+	shares, err := Split(secret, 5, 3)
+	if err != nil {
+		t.Fatalf("Split: %v", err)
+	}
+
+	// All C(5,3)=10 subsets should reconstruct
+	count := 0
+	for i := 0; i < 5; i++ {
+		for j := i + 1; j < 5; j++ {
+			for k := j + 1; k < 5; k++ {
+				result, err := Combine([]Share{shares[i], shares[j], shares[k]})
+				if err != nil {
+					t.Fatalf("Combine(%d,%d,%d): %v", i, j, k, err)
+				}
+				for idx := range secret {
+					if result[idx] != secret[idx] {
+						t.Errorf("Combine(%d,%d,%d)[%d] = %d, want %d", i, j, k, idx, result[idx], secret[idx])
+					}
+				}
+				count++
+			}
+		}
+	}
+	if count != 10 {
+		t.Errorf("tested %d subsets, want 10", count)
+	}
+}
+
+func TestSplitCombine_RoundTrip_LargeSecret(t *testing.T) {
+	secret := make([]byte, 256)
+	for i := range secret {
+		secret[i] = byte(i)
+	}
+	shares, err := Split(secret, 10, 5)
+	if err != nil {
+		t.Fatalf("Split: %v", err)
+	}
+
+	// Use first 5 shares
+	result, err := Combine(shares[:5])
+	if err != nil {
+		t.Fatalf("Combine: %v", err)
+	}
+	for i := range secret {
+		if result[i] != secret[i] {
+			t.Errorf("result[%d] = %d, want %d", i, result[i], secret[i])
+			break
+		}
+	}
+}
+
+func TestSplitCombine_AllZeros(t *testing.T) {
+	secret := make([]byte, 10)
+	shares, err := Split(secret, 5, 3)
+	if err != nil {
+		t.Fatalf("Split: %v", err)
+	}
+	result, err := Combine(shares[:3])
+	if err != nil {
+		t.Fatalf("Combine: %v", err)
+	}
+	for i, b := range result {
+		if b != 0 {
+			t.Errorf("result[%d] = %d, want 0", i, b)
+		}
+	}
+}
+
+func TestSplitCombine_AllOnes(t *testing.T) {
+	secret := make([]byte, 10)
+	for i := range secret {
+		secret[i] = 0xFF
+	}
+	shares, err := Split(secret, 5, 3)
+	if err != nil {
+		t.Fatalf("Split: %v", err)
+	}
+	result, err := Combine(shares[:3])
+	if err != nil {
+		t.Fatalf("Combine: %v", err)
+	}
+	for i, b := range result {
+		if b != 0xFF {
+			t.Errorf("result[%d] = %d, want 255", i, b)
+		}
+	}
+}
+
+// ── Share indices ─────────────────────────────────────────────────────────
+
+func TestSplit_ShareIndices(t *testing.T) {
+	shares, err := Split([]byte{42}, 5, 3)
+	if err != nil {
+		t.Fatalf("Split: %v", err)
+	}
+	for i, s := range shares {
+		if s.X != byte(i+1) {
+			t.Errorf("shares[%d].X = %d, want %d", i, s.X, i+1)
+		}
+	}
+}
+
+// ── Error cases ───────────────────────────────────────────────────────────
+
+func TestSplit_Errors(t *testing.T) {
+	tests := []struct {
+		name   string
+		secret []byte
+		n, k   int
+		want   error
+	}{
+		{"k < 2", []byte{1}, 3, 1, ErrThresholdTooSmall},
+		{"n < k", []byte{1}, 2, 3, ErrShareCountTooSmall},
+		{"n > 255", []byte{1}, 256, 3, ErrTooManyShares},
+		{"empty secret", []byte{}, 3, 2, ErrEmptySecret},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := Split(tt.secret, tt.n, tt.k)
+			if err != tt.want {
+				t.Errorf("Split() error = %v, want %v", err, tt.want)
+			}
+		})
+	}
+}
+
+func TestCombine_Errors(t *testing.T) {
+	t.Run("not enough shares", func(t *testing.T) {
+		_, err := Combine([]Share{{X: 1, Y: []byte{1}}})
+		if err != ErrNotEnoughShares {
+			t.Errorf("got %v, want ErrNotEnoughShares", err)
+		}
+	})
+
+	t.Run("zero index", func(t *testing.T) {
+		_, err := Combine([]Share{
+			{X: 0, Y: []byte{1}},
+			{X: 1, Y: []byte{2}},
+		})
+		if err != ErrZeroShareIndex {
+			t.Errorf("got %v, want ErrZeroShareIndex", err)
+		}
+	})
+
+	t.Run("mismatched lengths", func(t *testing.T) {
+		_, err := Combine([]Share{
+			{X: 1, Y: []byte{1, 2}},
+			{X: 2, Y: []byte{3}},
+		})
+		if err != ErrMismatchedShareLen {
+			t.Errorf("got %v, want ErrMismatchedShareLen", err)
+		}
+	})
+
+	t.Run("duplicate indices", func(t *testing.T) {
+		_, err := Combine([]Share{
+			{X: 1, Y: []byte{1}},
+			{X: 1, Y: []byte{2}},
+		})
+		if err != ErrDuplicateShareIndex {
+			t.Errorf("got %v, want ErrDuplicateShareIndex", err)
+		}
+	})
+}
+
+// ── Threshold / Quorum ────────────────────────────────────────────────────
+
+func TestAdaptiveThreshold(t *testing.T) {
+	tests := [][2]int{
+		{1, 3}, {2, 3}, {3, 3}, {5, 3}, {8, 3}, {9, 3},
+		{10, 3}, {12, 4}, {15, 5}, {30, 10}, {100, 33},
+	}
+	for _, tt := range tests {
+		if got := AdaptiveThreshold(tt[0]); got != tt[1] {
+			t.Errorf("AdaptiveThreshold(%d) = %d, want %d", tt[0], got, tt[1])
+		}
+	}
+}
+
+func TestWriteQuorum(t *testing.T) {
+	tests := [][2]int{
+		{0, 0}, {1, 1}, {2, 2}, {3, 2}, {4, 3}, {5, 4},
+		{6, 4}, {10, 7}, {14, 10}, {100, 67},
+	}
+	for _, tt := range tests {
+		if got := WriteQuorum(tt[0]); got != tt[1] {
+			t.Errorf("WriteQuorum(%d) = %d, want %d", tt[0], got, tt[1])
+		}
+	}
+}