diff --git a/CLAUDE.md b/CLAUDE.md
index 9496406..1d11444 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -15,13 +15,27 @@ Consumed by:
 | Bascule | `bascule/v1/` | 4 | Session, command, gateway, ceremony |
 | Workspace | `workspace/v1/` | 1 | Workspace management |
 | Runner | `runner/v1/` | 2 | Pipeline execution |
-| Schematic | `schematic/v1/` | 1 | Composite meta-artifacts |
+| Schematic | `schematic/v1/` | 2 | Composite meta-artifacts, infrastructure offerings |
+| Attestation | `attestation/v1/` | (if present) | Substrate attestation types |
 
 ## Versioning
 
 Proto files use domain-versioned paths (e.g., `quartermaster/v1/`). Breaking changes require a new version directory (e.g., `quartermaster/v2/`).
 
+## Build / Lint
+
+```bash
+# Lint protos (requires buf)
+buf lint
+
+# Breaking change detection
+buf breaking --against '.git#branch=main'
+```
+
+CI is configured in `.forgejo/workflows/ci.yaml` (buf lint + breaking change detection).
+
 ## Related Repos
 
-- `~/projects/guildhouse-platform/` -- Rust services that implement these APIs
+- `~/projects/guildhouse/` -- Rust services that implement these APIs
 - `~/projects/guildhouse-dashboard/` -- Django dashboard that calls these APIs
+- `~/projects/guildhouse-spire-plugins/` -- Go plugins (copies protos for local codegen)
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..a4d14b2
--- /dev/null
+++ b/README.md
@@ -0,0 +1,30 @@
+# Guildhouse Proto
+
+Canonical Protocol Buffer definitions for all Guildhouse gRPC services.
+
+## Domains
+
+| Domain | Directory | Purpose |
+|--------|-----------|---------|
+| Quartermaster | `quartermaster/v1/` | Governance, registry, notary, credentials, capabilities, pipelines |
+| Bascule | `bascule/v1/` | Session, command, gateway, ceremony |
+| Workspace | `workspace/v1/` | Workspace management |
+| Runner | `runner/v1/` | Pipeline execution |
+| Schematic | `schematic/v1/` | Composite meta-artifacts, infrastructure offerings |
+
+## Consumers
+
+- **guildhouse** (Rust/tonic-build) — via git submodule
+- **guildhouse-dashboard** (Python/grpcio-tools) — via git submodule
+- **guildhouse-spire-plugins** (Go) — copies proto files for local codegen
+
+## Lint
+
+```bash
+buf lint
+buf breaking --against '.git#branch=main'
+```
+
+## License
+
+Apache License 2.0
diff --git a/schematic/v1/infrastructure.proto b/schematic/v1/infrastructure.proto
new file mode 100644
index 0000000..0c5bbd5
--- /dev/null
+++ b/schematic/v1/infrastructure.proto
@@ -0,0 +1,142 @@
+syntax = "proto3";
+package schematic.v1;
+
+import "google/protobuf/timestamp.proto";
+
+// InfrastructureOffering describes a deployable platform configuration
+// available in the Guildhouse catalog. Entities subscribe to offerings
+// via accords to provision sites.
+message InfrastructureOffering {
+    string name = 1;
+    string version = 2;
+    string description = 3;
+
+    OSSpec os = 4;
+    KubernetesSpec kubernetes = 5;
+    HardwareRequirements hardware = 6;
+    GovernanceSpec governance = 7;
+    NetworkSpec network = 8;
+    CostModel cost = 9;
+
+    string tree_hash = 10;
+    string status = 11; // draft, published, deprecated
+    google.protobuf.Timestamp created_at = 12;
+    google.protobuf.Timestamp published_at = 13;
+}
+
+message OSSpec {
+    // "substrate-nos", "rhel", "ubuntu", "fedora", "debian"
+    string distribution = 1;
+    string version = 2;
+    // "x86_64", "aarch64"
+    string arch = 3;
+    // "yocto", "kickstart", "cloud-init", "pxe"
+    string install_method = 4;
+    string image_url = 5;
+}
+
+message KubernetesSpec {
+    // "k3s", "kubeadm", "none"
+    string distribution = 1;
+    string version = 2;
+    // "cilium", "kedge", "calico"
+    string cni = 3;
+    // "k3s", "kubeadm", "none"
+    string bootstrap_provider = 4;
+}
+
+message HardwareRequirements {
+    int32 min_cpu_cores = 1;
+    int64 min_memory_mb = 2;
+    int64 min_disk_gb = 3;
+    // "ipmi", "redfish", "idrac", "ilo"
+    string bmc_type = 4;
+    int32 min_nics = 5;
+    bool tpm_required = 6;
+}
+
+message GovernanceSpec {
+    // "basic", "standard", "strict"
+    string conformance_level = 1;
+    repeated CeremonyRequirement ceremonies = 2;
+}
+
+message CeremonyRequirement {
+    string operation = 1; // "provision", "upgrade", "decommission"
+    string tier = 2;      // "single", "dual", "multi-party"
+}
+
+message NetworkSpec {
+    // "overlay", "underlay", "dual"
+    string mode = 1;
+    bool wireguard_tunnel = 2;
+    bool vpp_dataplane = 3;
+    // VXLAN VNI range (if overlay)
+    int32 vni_start = 4;
+    int32 vni_end = 5;
+}
+
+message CostModel {
+    // Monthly cost estimate in cents (USD)
+    int64 monthly_cost_cents = 1;
+    string billing_entity = 2;
+}
+
+// Service for managing InfrastructureOfferings in the catalog.
+service InfrastructureOfferingService {
+    rpc CreateOffering(CreateOfferingRequest) returns (CreateOfferingResponse);
+    rpc GetOffering(GetOfferingRequest) returns (GetOfferingResponse);
+    rpc ListOfferings(ListOfferingsRequest) returns (ListOfferingsResponse);
+    rpc PublishOffering(PublishOfferingRequest) returns (PublishOfferingResponse);
+    rpc SubscribeToOffering(SubscribeRequest) returns (SubscribeResponse);
+}
+
+message CreateOfferingRequest {
+    InfrastructureOffering offering = 1;
+}
+
+message CreateOfferingResponse {
+    string name = 1;
+    string version = 2;
+    string tree_hash = 3;
+}
+
+message GetOfferingRequest {
+    string name = 1;
+    string version = 2;
+}
+
+message GetOfferingResponse {
+    InfrastructureOffering offering = 1;
+}
+
+message ListOfferingsRequest {
+    string status_filter = 1; // "" for all, "published", "draft"
+    string os_filter = 2;     // filter by OS distribution
+}
+
+message ListOfferingsResponse {
+    repeated InfrastructureOffering offerings = 1;
+}
+
+message PublishOfferingRequest {
+    string name = 1;
+    string version = 2;
+}
+
+message PublishOfferingResponse {
+    string tree_hash = 1;
+    string status = 2;
+}
+
+message SubscribeRequest {
+    string offering_name = 1;
+    string offering_version = 2;
+    string entity_id = 3;
+    string accord_id = 4;
+}
+
+message SubscribeResponse {
+    string subscription_id = 1;
+    string status = 2;
+}