Describe v0.8.2

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -150,3 +150,31 @@ jobs:
               || { echo "upload of $(basename "$f") was refused" >&2; exit 1; }
           done
           echo "attached $(ls dist | wc -l) files to $tag"
+
+  # The release page says what changed, copied from CHANGELOG.md. Gitea makes
+  # an empty release for every tag and the job above only attaches files, so
+  # every release until this existed was a list of binaries and nothing else.
+  #
+  # After the build, because that is what guarantees the release exists. Run by
+  # hand from a branch it syncs every version in the changelog, which is how
+  # the releases made before this got their notes.
+  notes:
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Copy the changelog onto the release
+        env:
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+          GITEA_INSTANCE: ${{ github.server_url }}
+          GITEA_REPO: ${{ github.repository }}
+        run: |
+          set -euo pipefail
+          if [ "${GITHUB_REF_TYPE:-}" = "tag" ]; then
+            python3 scripts/gitea/release_notes.py --tag "${GITHUB_REF_NAME}"
+          else
+            python3 scripts/gitea/release_notes.py
+          fi

CHANGELOG.md

@@ -18,6 +18,45 @@ is only released once its **exit criterion** is met, not when its code lands.
 Until v1.0.0 the minor version is the breaking one: configuration formats and Go
 APIs change between minors without a deprecation period.
 
+## v0.8.2 — 2026-09-28
+
+A node no longer runs whatever engine somebody once put on it. It installs its
+own.
+
+### Engines are installed by the node
+
+`engines:` in server.yaml names the engines every node has and their versions,
+defaulting to the llama.cpp build this release was checked against (b10991).
+Each agent converges on it: it picks the build for its hardware — CUDA with its
+runtime when an NVIDIA driver is loaded, CPU otherwise — installs the OS
+packages that build needs with the machine's own package manager, downloads the
+archive and checks it against the sha256 GitHub publishes, unpacks it refusing
+anything that would land outside its directory, and runs it. `ldd` names a
+missing library or a system too old for the build ("libstdc++.so.6 is too old
+(needs GLIBCXX_3.4.30)"); `--version` proves the rest. Installs are checked
+again every ten minutes.
+
+An engine is reported only once installed and seen to run, or when the agent's
+configuration names it on purpose. A node that has installed nothing yet is not
+a candidate for any model, where before it was a candidate for all of them.
+`ctl nodes`, the cluster page and placement's refusals say where each
+installation stands, and warn about a CPU without AVX2.
+
+Not every system is refused for its name: the build runs on Ubuntu 22.04+,
+Debian 12+ and RHEL-family 10, and `ldd` decides. vLLM and SGLang are not yet
+installed this way and must still be named in the agent's configuration.
+
+### Onboarding
+
+Onboarding installs llmgw from the CI release for the node's architecture,
+checked against the release's checksums, and writes an agent configuration of
+only the control plane's addresses and the TLS files.
+
+### Fixes
+
+- A race on the weights fingerprint, which two heartbeat loops touched during a
+  failover.
+
 ## v0.8.1 — 2026-09-28
 
 Nothing here changes a configuration format: every file that worked with

api/gen/llmgw/v1/agent.pb.go

@@ -90,7 +90,7 @@ func (x ShardStatus_State) Number() protoreflect.EnumNumber {
 
 // Deprecated: Use ShardStatus_State.Descriptor instead.
 func (ShardStatus_State) EnumDescriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{9, 0}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{13, 0}
 }
 
 // AgentMessage is anything a node tells the control plane.
@@ -202,6 +202,7 @@ type ControlMessage struct {
 	//	*ControlMessage_Drain
 	//	*ControlMessage_Ack
 	//	*ControlMessage_RemoveWeights
+	//	*ControlMessage_Provision
 	Msg           isControlMessage_Msg `protobuf_oneof:"msg"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
@@ -289,6 +290,15 @@ func (x *ControlMessage) GetRemoveWeights() *RemoveWeights {
 	return nil
 }
 
+func (x *ControlMessage) GetProvision() *Provision {
+	if x != nil {
+		if x, ok := x.Msg.(*ControlMessage_Provision); ok {
+			return x.Provision
+		}
+	}
+	return nil
+}
+
 type isControlMessage_Msg interface {
 	isControlMessage_Msg()
 }
@@ -313,6 +323,10 @@ type ControlMessage_RemoveWeights struct {
 	RemoveWeights *RemoveWeights `protobuf:"bytes,5,opt,name=remove_weights,json=removeWeights,proto3,oneof"`
 }
 
+type ControlMessage_Provision struct {
+	Provision *Provision `protobuf:"bytes,6,opt,name=provision,proto3,oneof"`
+}
+
 func (*ControlMessage_Start) isControlMessage_Msg() {}
 
 func (*ControlMessage_Stop) isControlMessage_Msg() {}
@@ -323,6 +337,8 @@ func (*ControlMessage_Ack) isControlMessage_Msg() {}
 
 func (*ControlMessage_RemoveWeights) isControlMessage_Msg() {}
 
+func (*ControlMessage_Provision) isControlMessage_Msg() {}
+
 // Register is the first message on every stream. It carries the node's full
 // hardware inventory, so the control plane needs no separate discovery call and
 // a reconnecting agent automatically refreshes what the scheduler knows.
@@ -381,7 +397,15 @@ type Register struct {
 	//
 	// Empty means the node was not asked to look, exactly as for weights, and
 	// constrains nothing.
-	Storage       []*Storage `protobuf:"bytes,12,rep,name=storage,proto3" json:"storage,omitempty"`
+	Storage []*Storage `protobuf:"bytes,12,rep,name=storage,proto3" json:"storage,omitempty"`
+	// host is what the machine is, so the control plane can have the mirror
+	// fetch software built for it rather than assuming every node matches the
+	// first.
+	Host *Host `protobuf:"bytes,13,opt,name=host,proto3" json:"host,omitempty"`
+	// engines_probed says engine_versions is an answer. Without it an empty map
+	// meant "an agent too old to say" and constrained nothing — so a freshly
+	// built node with no engine installed yet was a candidate for every model.
+	EnginesProbed bool `protobuf:"varint,14,opt,name=engines_probed,json=enginesProbed,proto3" json:"engines_probed,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@@ -500,6 +524,113 @@ func (x *Register) GetStorage() []*Storage {
 	return nil
 }
 
+func (x *Register) GetHost() *Host {
+	if x != nil {
+		return x.Host
+	}
+	return nil
+}
+
+func (x *Register) GetEnginesProbed() bool {
+	if x != nil {
+		return x.EnginesProbed
+	}
+	return false
+}
+
+// Host describes the operating system and processor of a node.
+type Host struct {
+	state protoimpl.MessageState `protogen:"open.v1"`
+	// From /etc/os-release: "ubuntu", "24.04", "noble".
+	OsId       string `protobuf:"bytes,1,opt,name=os_id,json=osId,proto3" json:"os_id,omitempty"`
+	OsVersion  string `protobuf:"bytes,2,opt,name=os_version,json=osVersion,proto3" json:"os_version,omitempty"`
+	OsCodename string `protobuf:"bytes,3,opt,name=os_codename,json=osCodename,proto3" json:"os_codename,omitempty"`
+	// Debian's spelling, which is what package indexes are keyed by: "amd64",
+	// "arm64".
+	Arch string `protobuf:"bytes,4,opt,name=arch,proto3" json:"arch,omitempty"`
+	// The vector extensions inference cares about, of those the CPU has. A VM
+	// given QEMU's default CPU model has none of them, and runs, and is five
+	// times slower, and nothing says why.
+	CpuFlags []string `protobuf:"bytes,5,rep,name=cpu_flags,json=cpuFlags,proto3" json:"cpu_flags,omitempty"`
+	// nvidia_driver is the driver version, empty when there is none. A card
+	// without a driver is not a GPU anything can use.
+	NvidiaDriver  string `protobuf:"bytes,6,opt,name=nvidia_driver,json=nvidiaDriver,proto3" json:"nvidia_driver,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *Host) Reset() {
+	*x = Host{}
+	mi := &file_llmgw_v1_agent_proto_msgTypes[3]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *Host) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*Host) ProtoMessage() {}
+
+func (x *Host) ProtoReflect() protoreflect.Message {
+	mi := &file_llmgw_v1_agent_proto_msgTypes[3]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use Host.ProtoReflect.Descriptor instead.
+func (*Host) Descriptor() ([]byte, []int) {
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{3}
+}
+
+func (x *Host) GetOsId() string {
+	if x != nil {
+		return x.OsId
+	}
+	return ""
+}
+
+func (x *Host) GetOsVersion() string {
+	if x != nil {
+		return x.OsVersion
+	}
+	return ""
+}
+
+func (x *Host) GetOsCodename() string {
+	if x != nil {
+		return x.OsCodename
+	}
+	return ""
+}
+
+func (x *Host) GetArch() string {
+	if x != nil {
+		return x.Arch
+	}
+	return ""
+}
+
+func (x *Host) GetCpuFlags() []string {
+	if x != nil {
+		return x.CpuFlags
+	}
+	return nil
+}
+
+func (x *Host) GetNvidiaDriver() string {
+	if x != nil {
+		return x.NvidiaDriver
+	}
+	return ""
+}
+
 // Storage is one filesystem a node keeps weights on.
 //
 // Per filesystem rather than per configured directory: free space belongs to
@@ -522,7 +653,7 @@ type Storage struct {
 
 func (x *Storage) Reset() {
 	*x = Storage{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[3]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[4]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -534,7 +665,7 @@ func (x *Storage) String() string {
 func (*Storage) ProtoMessage() {}
 
 func (x *Storage) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[3]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[4]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -547,7 +678,7 @@ func (x *Storage) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use Storage.ProtoReflect.Descriptor instead.
 func (*Storage) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{3}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{4}
 }
 
 func (x *Storage) GetPath() string {
@@ -614,7 +745,7 @@ type RunningShard struct {
 
 func (x *RunningShard) Reset() {
 	*x = RunningShard{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[4]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[5]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -626,7 +757,7 @@ func (x *RunningShard) String() string {
 func (*RunningShard) ProtoMessage() {}
 
 func (x *RunningShard) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[4]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[5]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -639,7 +770,7 @@ func (x *RunningShard) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use RunningShard.ProtoReflect.Descriptor instead.
 func (*RunningShard) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{4}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{5}
 }
 
 func (x *RunningShard) GetReplicaId() string {
@@ -776,7 +907,7 @@ type GPU struct {
 
 func (x *GPU) Reset() {
 	*x = GPU{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[5]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[6]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -788,7 +919,7 @@ func (x *GPU) String() string {
 func (*GPU) ProtoMessage() {}
 
 func (x *GPU) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[5]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[6]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -801,7 +932,7 @@ func (x *GPU) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use GPU.ProtoReflect.Descriptor instead.
 func (*GPU) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{5}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{6}
 }
 
 func (x *GPU) GetIndex() int32 {
@@ -923,7 +1054,7 @@ type FabricAttachment struct {
 
 func (x *FabricAttachment) Reset() {
 	*x = FabricAttachment{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[6]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[7]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -935,7 +1066,7 @@ func (x *FabricAttachment) String() string {
 func (*FabricAttachment) ProtoMessage() {}
 
 func (x *FabricAttachment) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[6]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[7]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -948,7 +1079,7 @@ func (x *FabricAttachment) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use FabricAttachment.ProtoReflect.Descriptor instead.
 func (*FabricAttachment) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{6}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{7}
 }
 
 func (x *FabricAttachment) GetFabric() string {
@@ -990,7 +1121,7 @@ type LocalWeights struct {
 
 func (x *LocalWeights) Reset() {
 	*x = LocalWeights{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[7]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[8]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -1002,7 +1133,7 @@ func (x *LocalWeights) String() string {
 func (*LocalWeights) ProtoMessage() {}
 
 func (x *LocalWeights) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[7]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[8]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -1015,7 +1146,7 @@ func (x *LocalWeights) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use LocalWeights.ProtoReflect.Descriptor instead.
 func (*LocalWeights) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{7}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{8}
 }
 
 func (x *LocalWeights) GetPath() string {
@@ -1070,13 +1201,18 @@ type Heartbeat struct {
 	// somebody restarts the agent — which is a step nobody knows to take.
 	EnginesChanged bool              `protobuf:"varint,8,opt,name=engines_changed,json=enginesChanged,proto3" json:"engines_changed,omitempty"`
 	EngineVersions map[string]string `protobuf:"bytes,9,rep,name=engine_versions,json=engineVersions,proto3" json:"engine_versions,omitempty" protobuf_key:"bytes,1,opt,name=key" protobuf_val:"bytes,2,opt,name=value"`
-	unknownFields  protoimpl.UnknownFields
-	sizeCache      protoimpl.SizeCache
+	// provision is where installing the node's software stands, sent when it
+	// changed. The flag makes an empty list mean "nothing to install" rather
+	// than "nothing to say", as for weights.
+	ProvisionChanged bool               `protobuf:"varint,10,opt,name=provision_changed,json=provisionChanged,proto3" json:"provision_changed,omitempty"`
+	Provision        []*ProvisionStatus `protobuf:"bytes,11,rep,name=provision,proto3" json:"provision,omitempty"`
+	unknownFields    protoimpl.UnknownFields
+	sizeCache        protoimpl.SizeCache
 }
 
 func (x *Heartbeat) Reset() {
 	*x = Heartbeat{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[8]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[9]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -1088,7 +1224,7 @@ func (x *Heartbeat) String() string {
 func (*Heartbeat) ProtoMessage() {}
 
 func (x *Heartbeat) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[8]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[9]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -1101,7 +1237,7 @@ func (x *Heartbeat) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use Heartbeat.ProtoReflect.Descriptor instead.
 func (*Heartbeat) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{8}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{9}
 }
 
 func (x *Heartbeat) GetNodeId() string {
@@ -1167,6 +1303,206 @@ func (x *Heartbeat) GetEngineVersions() map[string]string {
 	return nil
 }
 
+func (x *Heartbeat) GetProvisionChanged() bool {
+	if x != nil {
+		return x.ProvisionChanged
+	}
+	return false
+}
+
+func (x *Heartbeat) GetProvision() []*ProvisionStatus {
+	if x != nil {
+		return x.Provision
+	}
+	return nil
+}
+
+// Provision is the software a node should have: which engines, at which
+// versions. Nothing more.
+//
+// Everything else is the node's to work out, because only the node knows it:
+// which build fits its hardware, where that build is published, what its
+// operating system is missing, and whether the result actually runs. The agent
+// converges on this — installs what is absent, checks what is there — and
+// reports each engine through ProvisionStatus. Nothing is taken on trust from
+// what happens to be on the machine: an engine is offered to placement only
+// once the agent has installed it and seen it run.
+type Provision struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Engines       []*EngineWant          `protobuf:"bytes,1,rep,name=engines,proto3" json:"engines,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *Provision) Reset() {
+	*x = Provision{}
+	mi := &file_llmgw_v1_agent_proto_msgTypes[10]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *Provision) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*Provision) ProtoMessage() {}
+
+func (x *Provision) ProtoReflect() protoreflect.Message {
+	mi := &file_llmgw_v1_agent_proto_msgTypes[10]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use Provision.ProtoReflect.Descriptor instead.
+func (*Provision) Descriptor() ([]byte, []int) {
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{10}
+}
+
+func (x *Provision) GetEngines() []*EngineWant {
+	if x != nil {
+		return x.Engines
+	}
+	return nil
+}
+
+// EngineWant names one engine at one version.
+type EngineWant struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Engine        string                 `protobuf:"bytes,1,opt,name=engine,proto3" json:"engine,omitempty"`   // "llamacpp"
+	Version       string                 `protobuf:"bytes,2,opt,name=version,proto3" json:"version,omitempty"` // "b10991"
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *EngineWant) Reset() {
+	*x = EngineWant{}
+	mi := &file_llmgw_v1_agent_proto_msgTypes[11]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *EngineWant) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*EngineWant) ProtoMessage() {}
+
+func (x *EngineWant) ProtoReflect() protoreflect.Message {
+	mi := &file_llmgw_v1_agent_proto_msgTypes[11]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use EngineWant.ProtoReflect.Descriptor instead.
+func (*EngineWant) Descriptor() ([]byte, []int) {
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{11}
+}
+
+func (x *EngineWant) GetEngine() string {
+	if x != nil {
+		return x.Engine
+	}
+	return ""
+}
+
+func (x *EngineWant) GetVersion() string {
+	if x != nil {
+		return x.Version
+	}
+	return ""
+}
+
+// ProvisionStatus is where one engine's installation stands on a node.
+type ProvisionStatus struct {
+	state   protoimpl.MessageState `protogen:"open.v1"`
+	Engine  string                 `protobuf:"bytes,1,opt,name=engine,proto3" json:"engine,omitempty"`
+	Version string                 `protobuf:"bytes,2,opt,name=version,proto3" json:"version,omitempty"`
+	Variant string                 `protobuf:"bytes,3,opt,name=variant,proto3" json:"variant,omitempty"`
+	// "installing", "ready", "failed", or "unsupported" when no build fits.
+	State string `protobuf:"bytes,4,opt,name=state,proto3" json:"state,omitempty"`
+	// detail says what is happening or what went wrong, in words for a person.
+	Detail        string `protobuf:"bytes,5,opt,name=detail,proto3" json:"detail,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *ProvisionStatus) Reset() {
+	*x = ProvisionStatus{}
+	mi := &file_llmgw_v1_agent_proto_msgTypes[12]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *ProvisionStatus) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ProvisionStatus) ProtoMessage() {}
+
+func (x *ProvisionStatus) ProtoReflect() protoreflect.Message {
+	mi := &file_llmgw_v1_agent_proto_msgTypes[12]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ProvisionStatus.ProtoReflect.Descriptor instead.
+func (*ProvisionStatus) Descriptor() ([]byte, []int) {
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{12}
+}
+
+func (x *ProvisionStatus) GetEngine() string {
+	if x != nil {
+		return x.Engine
+	}
+	return ""
+}
+
+func (x *ProvisionStatus) GetVersion() string {
+	if x != nil {
+		return x.Version
+	}
+	return ""
+}
+
+func (x *ProvisionStatus) GetVariant() string {
+	if x != nil {
+		return x.Variant
+	}
+	return ""
+}
+
+func (x *ProvisionStatus) GetState() string {
+	if x != nil {
+		return x.State
+	}
+	return ""
+}
+
+func (x *ProvisionStatus) GetDetail() string {
+	if x != nil {
+		return x.Detail
+	}
+	return ""
+}
+
 // ShardStatus reports a shard's lifecycle transition.
 type ShardStatus struct {
 	state     protoimpl.MessageState `protogen:"open.v1"`
@@ -1193,7 +1529,7 @@ type ShardStatus struct {
 
 func (x *ShardStatus) Reset() {
 	*x = ShardStatus{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[9]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[13]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -1205,7 +1541,7 @@ func (x *ShardStatus) String() string {
 func (*ShardStatus) ProtoMessage() {}
 
 func (x *ShardStatus) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[9]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[13]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -1218,7 +1554,7 @@ func (x *ShardStatus) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use ShardStatus.ProtoReflect.Descriptor instead.
 func (*ShardStatus) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{9}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{13}
 }
 
 func (x *ShardStatus) GetNodeId() string {
@@ -1292,7 +1628,7 @@ type FetchProgress struct {
 
 func (x *FetchProgress) Reset() {
 	*x = FetchProgress{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[10]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[14]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -1304,7 +1640,7 @@ func (x *FetchProgress) String() string {
 func (*FetchProgress) ProtoMessage() {}
 
 func (x *FetchProgress) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[10]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[14]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -1317,7 +1653,7 @@ func (x *FetchProgress) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use FetchProgress.ProtoReflect.Descriptor instead.
 func (*FetchProgress) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{10}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{14}
 }
 
 func (x *FetchProgress) GetSource() string {
@@ -1373,7 +1709,7 @@ type StartShard struct {
 
 func (x *StartShard) Reset() {
 	*x = StartShard{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[11]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[15]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -1385,7 +1721,7 @@ func (x *StartShard) String() string {
 func (*StartShard) ProtoMessage() {}
 
 func (x *StartShard) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[11]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[15]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -1398,7 +1734,7 @@ func (x *StartShard) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use StartShard.ProtoReflect.Descriptor instead.
 func (*StartShard) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{11}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{15}
 }
 
 func (x *StartShard) GetReplicaId() string {
@@ -1525,7 +1861,7 @@ type EngineProfile struct {
 
 func (x *EngineProfile) Reset() {
 	*x = EngineProfile{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[12]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[16]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -1537,7 +1873,7 @@ func (x *EngineProfile) String() string {
 func (*EngineProfile) ProtoMessage() {}
 
 func (x *EngineProfile) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[12]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[16]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -1550,7 +1886,7 @@ func (x *EngineProfile) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use EngineProfile.ProtoReflect.Descriptor instead.
 func (*EngineProfile) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{12}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{16}
 }
 
 func (x *EngineProfile) GetName() string {
@@ -1646,7 +1982,7 @@ type RemoveWeights struct {
 
 func (x *RemoveWeights) Reset() {
 	*x = RemoveWeights{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[13]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[17]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -1658,7 +1994,7 @@ func (x *RemoveWeights) String() string {
 func (*RemoveWeights) ProtoMessage() {}
 
 func (x *RemoveWeights) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[13]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[17]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -1671,7 +2007,7 @@ func (x *RemoveWeights) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use RemoveWeights.ProtoReflect.Descriptor instead.
 func (*RemoveWeights) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{13}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{17}
 }
 
 func (x *RemoveWeights) GetPaths() []string {
@@ -1691,7 +2027,7 @@ type StopShard struct {
 
 func (x *StopShard) Reset() {
 	*x = StopShard{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[14]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[18]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -1703,7 +2039,7 @@ func (x *StopShard) String() string {
 func (*StopShard) ProtoMessage() {}
 
 func (x *StopShard) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[14]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[18]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -1716,7 +2052,7 @@ func (x *StopShard) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use StopShard.ProtoReflect.Descriptor instead.
 func (*StopShard) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{14}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{18}
 }
 
 func (x *StopShard) GetShardId() string {
@@ -1736,7 +2072,7 @@ type DrainShard struct {
 
 func (x *DrainShard) Reset() {
 	*x = DrainShard{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[15]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[19]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -1748,7 +2084,7 @@ func (x *DrainShard) String() string {
 func (*DrainShard) ProtoMessage() {}
 
 func (x *DrainShard) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[15]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[19]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -1761,7 +2097,7 @@ func (x *DrainShard) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use DrainShard.ProtoReflect.Descriptor instead.
 func (*DrainShard) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{15}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{19}
 }
 
 func (x *DrainShard) GetShardId() string {
@@ -1783,7 +2119,7 @@ type Ack struct {
 
 func (x *Ack) Reset() {
 	*x = Ack{}
-	mi := &file_llmgw_v1_agent_proto_msgTypes[16]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[20]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -1795,7 +2131,7 @@ func (x *Ack) String() string {
 func (*Ack) ProtoMessage() {}
 
 func (x *Ack) ProtoReflect() protoreflect.Message {
-	mi := &file_llmgw_v1_agent_proto_msgTypes[16]
+	mi := &file_llmgw_v1_agent_proto_msgTypes[20]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -1808,7 +2144,7 @@ func (x *Ack) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use Ack.ProtoReflect.Descriptor instead.
 func (*Ack) Descriptor() ([]byte, []int) {
-	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{16}
+	return file_llmgw_v1_agent_proto_rawDescGZIP(), []int{20}
 }
 
 func (x *Ack) GetMessageId() string {
@@ -1841,14 +2177,15 @@ const file_llmgw_v1_agent_proto_rawDesc = "" +
 	"\bregister\x18\x01 \x01(\v2\x12.llmgw.v1.RegisterH\x00R\bregister\x123\n" +
 	"\theartbeat\x18\x02 \x01(\v2\x13.llmgw.v1.HeartbeatH\x00R\theartbeat\x12-\n" +
 	"\x05shard\x18\x03 \x01(\v2\x15.llmgw.v1.ShardStatusH\x00R\x05shardB\x05\n" +
-	"\x03msg\"\x83\x02\n" +
+	"\x03msg\"\xb8\x02\n" +
 	"\x0eControlMessage\x12,\n" +
 	"\x05start\x18\x01 \x01(\v2\x14.llmgw.v1.StartShardH\x00R\x05start\x12)\n" +
 	"\x04stop\x18\x02 \x01(\v2\x13.llmgw.v1.StopShardH\x00R\x04stop\x12,\n" +
 	"\x05drain\x18\x03 \x01(\v2\x14.llmgw.v1.DrainShardH\x00R\x05drain\x12!\n" +
 	"\x03ack\x18\x04 \x01(\v2\r.llmgw.v1.AckH\x00R\x03ack\x12@\n" +
-	"\x0eremove_weights\x18\x05 \x01(\v2\x17.llmgw.v1.RemoveWeightsH\x00R\rremoveWeightsB\x05\n" +
-	"\x03msg\"\xa7\x05\n" +
+	"\x0eremove_weights\x18\x05 \x01(\v2\x17.llmgw.v1.RemoveWeightsH\x00R\rremoveWeights\x123\n" +
+	"\tprovision\x18\x06 \x01(\v2\x13.llmgw.v1.ProvisionH\x00R\tprovisionB\x05\n" +
+	"\x03msg\"\xf2\x05\n" +
 	"\bRegister\x12\x17\n" +
 	"\anode_id\x18\x01 \x01(\tR\x06nodeId\x12\x1a\n" +
 	"\bhostname\x18\x02 \x01(\tR\bhostname\x12\x1b\n" +
@@ -1862,13 +2199,24 @@ const file_llmgw_v1_agent_proto_rawDesc = "" +
 	"\x0fmemory_total_mb\x18\n" +
 	" \x01(\x03R\rmemoryTotalMb\x120\n" +
 	"\aweights\x18\v \x03(\v2\x16.llmgw.v1.LocalWeightsR\aweights\x12+\n" +
-	"\astorage\x18\f \x03(\v2\x11.llmgw.v1.StorageR\astorage\x1a9\n" +
+	"\astorage\x18\f \x03(\v2\x11.llmgw.v1.StorageR\astorage\x12\"\n" +
+	"\x04host\x18\r \x01(\v2\x0e.llmgw.v1.HostR\x04host\x12%\n" +
+	"\x0eengines_probed\x18\x0e \x01(\bR\renginesProbed\x1a9\n" +
 	"\vLabelsEntry\x12\x10\n" +
 	"\x03key\x18\x01 \x01(\tR\x03key\x12\x14\n" +
 	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\x1aA\n" +
 	"\x13EngineVersionsEntry\x12\x10\n" +
 	"\x03key\x18\x01 \x01(\tR\x03key\x12\x14\n" +
-	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\"u\n" +
+	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\"\xb1\x01\n" +
+	"\x04Host\x12\x13\n" +
+	"\x05os_id\x18\x01 \x01(\tR\x04osId\x12\x1d\n" +
+	"\n" +
+	"os_version\x18\x02 \x01(\tR\tosVersion\x12\x1f\n" +
+	"\vos_codename\x18\x03 \x01(\tR\n" +
+	"osCodename\x12\x12\n" +
+	"\x04arch\x18\x04 \x01(\tR\x04arch\x12\x1b\n" +
+	"\tcpu_flags\x18\x05 \x03(\tR\bcpuFlags\x12#\n" +
+	"\rnvidia_driver\x18\x06 \x01(\tR\fnvidiaDriver\"u\n" +
 	"\aStorage\x12\x12\n" +
 	"\x04path\x18\x01 \x01(\tR\x04path\x12\x1d\n" +
 	"\n" +
@@ -1925,7 +2273,7 @@ const file_llmgw_v1_agent_proto_rawDesc = "" +
 	"\x04path\x18\x01 \x01(\tR\x04path\x12\x1d\n" +
 	"\n" +
 	"size_bytes\x18\x02 \x01(\x03R\tsizeBytes\x12\x16\n" +
-	"\x06shared\x18\x03 \x01(\bR\x06shared\"\xe2\x03\n" +
+	"\x06shared\x18\x03 \x01(\bR\x06shared\"\xc8\x04\n" +
 	"\tHeartbeat\x12\x17\n" +
 	"\anode_id\x18\x01 \x01(\tR\x06nodeId\x12+\n" +
 	"\x12gpu_memory_used_mb\x18\x02 \x03(\x05R\x0fgpuMemoryUsedMb\x12!\n" +
@@ -1935,10 +2283,25 @@ const file_llmgw_v1_agent_proto_rawDesc = "" +
 	"\aweights\x18\x06 \x03(\v2\x16.llmgw.v1.LocalWeightsR\aweights\x12&\n" +
 	"\x0fmemory_total_mb\x18\a \x01(\x03R\rmemoryTotalMb\x12'\n" +
 	"\x0fengines_changed\x18\b \x01(\bR\x0eenginesChanged\x12P\n" +
-	"\x0fengine_versions\x18\t \x03(\v2'.llmgw.v1.Heartbeat.EngineVersionsEntryR\x0eengineVersions\x1aA\n" +
+	"\x0fengine_versions\x18\t \x03(\v2'.llmgw.v1.Heartbeat.EngineVersionsEntryR\x0eengineVersions\x12+\n" +
+	"\x11provision_changed\x18\n" +
+	" \x01(\bR\x10provisionChanged\x127\n" +
+	"\tprovision\x18\v \x03(\v2\x19.llmgw.v1.ProvisionStatusR\tprovision\x1aA\n" +
 	"\x13EngineVersionsEntry\x12\x10\n" +
 	"\x03key\x18\x01 \x01(\tR\x03key\x12\x14\n" +
-	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\"\xbb\x03\n" +
+	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\";\n" +
+	"\tProvision\x12.\n" +
+	"\aengines\x18\x01 \x03(\v2\x14.llmgw.v1.EngineWantR\aengines\">\n" +
+	"\n" +
+	"EngineWant\x12\x16\n" +
+	"\x06engine\x18\x01 \x01(\tR\x06engine\x12\x18\n" +
+	"\aversion\x18\x02 \x01(\tR\aversion\"\x8b\x01\n" +
+	"\x0fProvisionStatus\x12\x16\n" +
+	"\x06engine\x18\x01 \x01(\tR\x06engine\x12\x18\n" +
+	"\aversion\x18\x02 \x01(\tR\aversion\x12\x18\n" +
+	"\avariant\x18\x03 \x01(\tR\avariant\x12\x14\n" +
+	"\x05state\x18\x04 \x01(\tR\x05state\x12\x16\n" +
+	"\x06detail\x18\x05 \x01(\tR\x06detail\"\xbb\x03\n" +
 	"\vShardStatus\x12\x17\n" +
 	"\anode_id\x18\x01 \x01(\tR\x06nodeId\x12\x1d\n" +
 	"\n" +
@@ -2035,62 +2398,70 @@ func file_llmgw_v1_agent_proto_rawDescGZIP() []byte {
 }
 
 var file_llmgw_v1_agent_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
-var file_llmgw_v1_agent_proto_msgTypes = make([]protoimpl.MessageInfo, 21)
+var file_llmgw_v1_agent_proto_msgTypes = make([]protoimpl.MessageInfo, 25)
 var file_llmgw_v1_agent_proto_goTypes = []any{
 	(ShardStatus_State)(0),   // 0: llmgw.v1.ShardStatus.State
 	(*AgentMessage)(nil),     // 1: llmgw.v1.AgentMessage
 	(*ControlMessage)(nil),   // 2: llmgw.v1.ControlMessage
 	(*Register)(nil),         // 3: llmgw.v1.Register
-	(*Storage)(nil),          // 4: llmgw.v1.Storage
-	(*RunningShard)(nil),     // 5: llmgw.v1.RunningShard
-	(*GPU)(nil),              // 6: llmgw.v1.GPU
-	(*FabricAttachment)(nil), // 7: llmgw.v1.FabricAttachment
-	(*LocalWeights)(nil),     // 8: llmgw.v1.LocalWeights
-	(*Heartbeat)(nil),        // 9: llmgw.v1.Heartbeat
-	(*ShardStatus)(nil),      // 10: llmgw.v1.ShardStatus
-	(*FetchProgress)(nil),    // 11: llmgw.v1.FetchProgress
-	(*StartShard)(nil),       // 12: llmgw.v1.StartShard
-	(*EngineProfile)(nil),    // 13: llmgw.v1.EngineProfile
-	(*RemoveWeights)(nil),    // 14: llmgw.v1.RemoveWeights
-	(*StopShard)(nil),        // 15: llmgw.v1.StopShard
-	(*DrainShard)(nil),       // 16: llmgw.v1.DrainShard
-	(*Ack)(nil),              // 17: llmgw.v1.Ack
-	nil,                      // 18: llmgw.v1.Register.LabelsEntry
-	nil,                      // 19: llmgw.v1.Register.EngineVersionsEntry
-	nil,                      // 20: llmgw.v1.Heartbeat.EngineVersionsEntry
-	nil,                      // 21: llmgw.v1.EngineProfile.EnvEntry
+	(*Host)(nil),             // 4: llmgw.v1.Host
+	(*Storage)(nil),          // 5: llmgw.v1.Storage
+	(*RunningShard)(nil),     // 6: llmgw.v1.RunningShard
+	(*GPU)(nil),              // 7: llmgw.v1.GPU
+	(*FabricAttachment)(nil), // 8: llmgw.v1.FabricAttachment
+	(*LocalWeights)(nil),     // 9: llmgw.v1.LocalWeights
+	(*Heartbeat)(nil),        // 10: llmgw.v1.Heartbeat
+	(*Provision)(nil),        // 11: llmgw.v1.Provision
+	(*EngineWant)(nil),       // 12: llmgw.v1.EngineWant
+	(*ProvisionStatus)(nil),  // 13: llmgw.v1.ProvisionStatus
+	(*ShardStatus)(nil),      // 14: llmgw.v1.ShardStatus
+	(*FetchProgress)(nil),    // 15: llmgw.v1.FetchProgress
+	(*StartShard)(nil),       // 16: llmgw.v1.StartShard
+	(*EngineProfile)(nil),    // 17: llmgw.v1.EngineProfile
+	(*RemoveWeights)(nil),    // 18: llmgw.v1.RemoveWeights
+	(*StopShard)(nil),        // 19: llmgw.v1.StopShard
+	(*DrainShard)(nil),       // 20: llmgw.v1.DrainShard
+	(*Ack)(nil),              // 21: llmgw.v1.Ack
+	nil,                      // 22: llmgw.v1.Register.LabelsEntry
+	nil,                      // 23: llmgw.v1.Register.EngineVersionsEntry
+	nil,                      // 24: llmgw.v1.Heartbeat.EngineVersionsEntry
+	nil,                      // 25: llmgw.v1.EngineProfile.EnvEntry
 }
 var file_llmgw_v1_agent_proto_depIdxs = []int32{
 	3,  // 0: llmgw.v1.AgentMessage.register:type_name -> llmgw.v1.Register
-	9,  // 1: llmgw.v1.AgentMessage.heartbeat:type_name -> llmgw.v1.Heartbeat
-	10, // 2: llmgw.v1.AgentMessage.shard:type_name -> llmgw.v1.ShardStatus
-	12, // 3: llmgw.v1.ControlMessage.start:type_name -> llmgw.v1.StartShard
-	15, // 4: llmgw.v1.ControlMessage.stop:type_name -> llmgw.v1.StopShard
-	16, // 5: llmgw.v1.ControlMessage.drain:type_name -> llmgw.v1.DrainShard
-	17, // 6: llmgw.v1.ControlMessage.ack:type_name -> llmgw.v1.Ack
-	14, // 7: llmgw.v1.ControlMessage.remove_weights:type_name -> llmgw.v1.RemoveWeights
-	18, // 8: llmgw.v1.Register.labels:type_name -> llmgw.v1.Register.LabelsEntry
-	6,  // 9: llmgw.v1.Register.gpus:type_name -> llmgw.v1.GPU
-	7,  // 10: llmgw.v1.Register.fabrics:type_name -> llmgw.v1.FabricAttachment
-	19, // 11: llmgw.v1.Register.engine_versions:type_name -> llmgw.v1.Register.EngineVersionsEntry
-	5,  // 12: llmgw.v1.Register.running_shards:type_name -> llmgw.v1.RunningShard
-	8,  // 13: llmgw.v1.Register.weights:type_name -> llmgw.v1.LocalWeights
-	4,  // 14: llmgw.v1.Register.storage:type_name -> llmgw.v1.Storage
-	0,  // 15: llmgw.v1.RunningShard.state:type_name -> llmgw.v1.ShardStatus.State
-	4,  // 16: llmgw.v1.Heartbeat.storage:type_name -> llmgw.v1.Storage
-	8,  // 17: llmgw.v1.Heartbeat.weights:type_name -> llmgw.v1.LocalWeights
-	20, // 18: llmgw.v1.Heartbeat.engine_versions:type_name -> llmgw.v1.Heartbeat.EngineVersionsEntry
-	0,  // 19: llmgw.v1.ShardStatus.state:type_name -> llmgw.v1.ShardStatus.State
-	11, // 20: llmgw.v1.ShardStatus.fetch:type_name -> llmgw.v1.FetchProgress
-	13, // 21: llmgw.v1.StartShard.profile:type_name -> llmgw.v1.EngineProfile
-	21, // 22: llmgw.v1.EngineProfile.env:type_name -> llmgw.v1.EngineProfile.EnvEntry
-	1,  // 23: llmgw.v1.AgentService.Connect:input_type -> llmgw.v1.AgentMessage
-	2,  // 24: llmgw.v1.AgentService.Connect:output_type -> llmgw.v1.ControlMessage
-	24, // [24:25] is the sub-list for method output_type
-	23, // [23:24] is the sub-list for method input_type
-	23, // [23:23] is the sub-list for extension type_name
-	23, // [23:23] is the sub-list for extension extendee
-	0,  // [0:23] is the sub-list for field type_name
+	10, // 1: llmgw.v1.AgentMessage.heartbeat:type_name -> llmgw.v1.Heartbeat
+	14, // 2: llmgw.v1.AgentMessage.shard:type_name -> llmgw.v1.ShardStatus
+	16, // 3: llmgw.v1.ControlMessage.start:type_name -> llmgw.v1.StartShard
+	19, // 4: llmgw.v1.ControlMessage.stop:type_name -> llmgw.v1.StopShard
+	20, // 5: llmgw.v1.ControlMessage.drain:type_name -> llmgw.v1.DrainShard
+	21, // 6: llmgw.v1.ControlMessage.ack:type_name -> llmgw.v1.Ack
+	18, // 7: llmgw.v1.ControlMessage.remove_weights:type_name -> llmgw.v1.RemoveWeights
+	11, // 8: llmgw.v1.ControlMessage.provision:type_name -> llmgw.v1.Provision
+	22, // 9: llmgw.v1.Register.labels:type_name -> llmgw.v1.Register.LabelsEntry
+	7,  // 10: llmgw.v1.Register.gpus:type_name -> llmgw.v1.GPU
+	8,  // 11: llmgw.v1.Register.fabrics:type_name -> llmgw.v1.FabricAttachment
+	23, // 12: llmgw.v1.Register.engine_versions:type_name -> llmgw.v1.Register.EngineVersionsEntry
+	6,  // 13: llmgw.v1.Register.running_shards:type_name -> llmgw.v1.RunningShard
+	9,  // 14: llmgw.v1.Register.weights:type_name -> llmgw.v1.LocalWeights
+	5,  // 15: llmgw.v1.Register.storage:type_name -> llmgw.v1.Storage
+	4,  // 16: llmgw.v1.Register.host:type_name -> llmgw.v1.Host
+	0,  // 17: llmgw.v1.RunningShard.state:type_name -> llmgw.v1.ShardStatus.State
+	5,  // 18: llmgw.v1.Heartbeat.storage:type_name -> llmgw.v1.Storage
+	9,  // 19: llmgw.v1.Heartbeat.weights:type_name -> llmgw.v1.LocalWeights
+	24, // 20: llmgw.v1.Heartbeat.engine_versions:type_name -> llmgw.v1.Heartbeat.EngineVersionsEntry
+	13, // 21: llmgw.v1.Heartbeat.provision:type_name -> llmgw.v1.ProvisionStatus
+	12, // 22: llmgw.v1.Provision.engines:type_name -> llmgw.v1.EngineWant
+	0,  // 23: llmgw.v1.ShardStatus.state:type_name -> llmgw.v1.ShardStatus.State
+	15, // 24: llmgw.v1.ShardStatus.fetch:type_name -> llmgw.v1.FetchProgress
+	17, // 25: llmgw.v1.StartShard.profile:type_name -> llmgw.v1.EngineProfile
+	25, // 26: llmgw.v1.EngineProfile.env:type_name -> llmgw.v1.EngineProfile.EnvEntry
+	1,  // 27: llmgw.v1.AgentService.Connect:input_type -> llmgw.v1.AgentMessage
+	2,  // 28: llmgw.v1.AgentService.Connect:output_type -> llmgw.v1.ControlMessage
+	28, // [28:29] is the sub-list for method output_type
+	27, // [27:28] is the sub-list for method input_type
+	27, // [27:27] is the sub-list for extension type_name
+	27, // [27:27] is the sub-list for extension extendee
+	0,  // [0:27] is the sub-list for field type_name
 }
 
 func init() { file_llmgw_v1_agent_proto_init() }
@@ -2109,6 +2480,7 @@ func file_llmgw_v1_agent_proto_init() {
 		(*ControlMessage_Drain)(nil),
 		(*ControlMessage_Ack)(nil),
 		(*ControlMessage_RemoveWeights)(nil),
+		(*ControlMessage_Provision)(nil),
 	}
 	type x struct{}
 	out := protoimpl.TypeBuilder{
@@ -2116,7 +2488,7 @@ func file_llmgw_v1_agent_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_llmgw_v1_agent_proto_rawDesc), len(file_llmgw_v1_agent_proto_rawDesc)),
 			NumEnums:      1,
-			NumMessages:   21,
+			NumMessages:   25,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

api/proto/llmgw/v1/agent.proto

@@ -34,6 +34,7 @@ message ControlMessage {
     DrainShard drain = 3;
     Ack ack = 4;
     RemoveWeights remove_weights = 5;
+    Provision provision = 6;
   }
 }
 
@@ -101,6 +102,34 @@ message Register {
   // Empty means the node was not asked to look, exactly as for weights, and
   // constrains nothing.
   repeated Storage storage = 12;
+
+  // host is what the machine is, so the control plane can have the mirror
+  // fetch software built for it rather than assuming every node matches the
+  // first.
+  Host host = 13;
+
+  // engines_probed says engine_versions is an answer. Without it an empty map
+  // meant "an agent too old to say" and constrained nothing — so a freshly
+  // built node with no engine installed yet was a candidate for every model.
+  bool engines_probed = 14;
+}
+
+// Host describes the operating system and processor of a node.
+message Host {
+  // From /etc/os-release: "ubuntu", "24.04", "noble".
+  string os_id = 1;
+  string os_version = 2;
+  string os_codename = 3;
+  // Debian's spelling, which is what package indexes are keyed by: "amd64",
+  // "arm64".
+  string arch = 4;
+  // The vector extensions inference cares about, of those the CPU has. A VM
+  // given QEMU's default CPU model has none of them, and runs, and is five
+  // times slower, and nothing says why.
+  repeated string cpu_flags = 5;
+  // nvidia_driver is the driver version, empty when there is none. A card
+  // without a driver is not a GPU anything can use.
+  string nvidia_driver = 6;
 }
 
 // Storage is one filesystem a node keeps weights on.
@@ -234,6 +263,43 @@ message Heartbeat {
   // somebody restarts the agent — which is a step nobody knows to take.
   bool engines_changed = 8;
   map<string, string> engine_versions = 9;
+
+  // provision is where installing the node's software stands, sent when it
+  // changed. The flag makes an empty list mean "nothing to install" rather
+  // than "nothing to say", as for weights.
+  bool provision_changed = 10;
+  repeated ProvisionStatus provision = 11;
+}
+
+// Provision is the software a node should have: which engines, at which
+// versions. Nothing more.
+//
+// Everything else is the node's to work out, because only the node knows it:
+// which build fits its hardware, where that build is published, what its
+// operating system is missing, and whether the result actually runs. The agent
+// converges on this — installs what is absent, checks what is there — and
+// reports each engine through ProvisionStatus. Nothing is taken on trust from
+// what happens to be on the machine: an engine is offered to placement only
+// once the agent has installed it and seen it run.
+message Provision {
+  repeated EngineWant engines = 1;
+}
+
+// EngineWant names one engine at one version.
+message EngineWant {
+  string engine = 1;  // "llamacpp"
+  string version = 2; // "b10991"
+}
+
+// ProvisionStatus is where one engine's installation stands on a node.
+message ProvisionStatus {
+  string engine = 1;
+  string version = 2;
+  string variant = 3;
+  // "installing", "ready", "failed", or "unsupported" when no build fits.
+  string state = 4;
+  // detail says what is happening or what went wrong, in words for a person.
+  string detail = 5;
 }
 
 // ShardStatus reports a shard's lifecycle transition.

deploy/bootstrap/add-node.sh

@@ -108,6 +108,5 @@ echo "== 2/2  onboarding $NAME"
 echo
 echo "Check it with: llmgw ctl nodes"
 echo
-echo "A node is not finished until the engines its profiles name are installed"
-echo "and the weights are on disk. Onboarding checks that a configured engine"
-echo "runs, but it installs neither — see docs/node-onboarding.md."
+echo "The agent installs its engines itself; the node takes no model until they"
+echo "are installed and seen to run. 'llmgw ctl nodes' shows where that stands."

deploy/bootstrap/onboard-node.sh

@@ -33,8 +33,8 @@ usage: $0 --node ID --addr HOST --server URL [options]
                     address on the route to --server, found by the agent)
   --mgmt-if NAME    interface NCCL bootstraps over (default: the one holding
                     that address)
-  --llamacpp-bin P  path to llama-server (default: PATH, then /opt/llama.cpp)
-  --vllm-bin P      path to the vllm entry point
+  --llamacpp-bin P  use this llama-server instead of the one the agent installs
+  --vllm-bin P      path to the vllm entry point (not yet installed by the agent)
   --sglang-python P python interpreter of the SGLang virtualenv
   --nvidia-smi PATH where nvidia-smi lives, when it is not on PATH. Containerized
                     driver installs routinely put it somewhere else.
@@ -44,6 +44,8 @@ usage: $0 --node ID --addr HOST --server URL [options]
                     Releases carry static linux/amd64 and linux/arm64 builds;
                     downloading one is better than copying whatever happens to
                     be on the machine you are running this from.
+  --releases URL    where release binaries are downloaded from (default the
+                    project's Gitea releases)
   --ssh-user NAME   (default ilker)
 USAGE
   exit 2
@@ -54,6 +56,7 @@ NVIDIA_SMI= IB_ROOT=/sys/class/infiniband
 LLAMACPP_BIN= VLLM_BIN= SGLANG_PYTHON=
 SSH_WAIT=180
 PKI=/etc/llmgw/pki BINARY= SSH_USER=ilker
+RELEASES=https://gitea.mynodes.xyz/ilker/llmgw/releases/download
 FABRIC_NAME= FABRIC_HCAS="mlx5_0,mlx5_1"
 
 while [ $# -gt 0 ]; do
@@ -71,6 +74,7 @@ while [ $# -gt 0 ]; do
     --ib-root) IB_ROOT="$2"; shift 2;;
     --pki) PKI="$2"; shift 2;;
     --binary) BINARY="$2"; shift 2;;
+    --releases) RELEASES="$2"; shift 2;;
     --ssh-user) SSH_USER="$2"; shift 2;;
     *) usage;;
   esac
@@ -131,9 +135,28 @@ $SSH "set -e
   rm -f /tmp/ca.pem /tmp/$NODE.pem /tmp/$NODE-key.pem"
 
 # 4. The binary, the configuration and the unit.
-say "installing the binary"
-scp -q $SSHOPTS "$BINARY" "$SSH_USER@$ADDR:/tmp/llmgw"
-$SSH 'sudo install -m 0755 /tmp/llmgw /usr/local/bin/llmgw && rm -f /tmp/llmgw'
+# The node fetches the release CI built for this version, for its own
+# architecture, and checks it against the release's checksums — rather than
+# being handed whatever binary is on the machine running this script. A build
+# that is not a release (a developer's, with commits past the tag) has no such
+# file, and is copied as before.
+TAG="$("$BINARY" --version 2>/dev/null | awk '{print $NF}')"
+if printf '%s' "$TAG" | grep -Eq '^v[0-9]+\.[0-9]+\.[0-9]+$'; then
+  say "installing llmgw $TAG from the release"
+  $SSH "set -e
+    arch=\$(dpkg --print-architecture)
+    name=llmgw-$TAG-linux-\$arch
+    cd /tmp && rm -f \$name checksums.txt
+    curl -fsSL -o \$name '$RELEASES/$TAG/'\$name
+    curl -fsSL -o checksums.txt '$RELEASES/$TAG/checksums.txt'
+    grep \" \$name\\\$\" checksums.txt | sha256sum -c - >/dev/null
+    sudo install -m 0755 \$name /usr/local/bin/llmgw
+    rm -f \$name checksums.txt"
+else
+  say "installing the binary (${TAG:-unversioned}, not a release)"
+  scp -q $SSHOPTS "$BINARY" "$SSH_USER@$ADDR:/tmp/llmgw"
+  $SSH 'sudo install -m 0755 /tmp/llmgw /usr/local/bin/llmgw && rm -f /tmp/llmgw'
+fi
 
 say "writing the configuration"
 NODE_IS_HOSTNAME=no
@@ -242,8 +265,9 @@ $SSH 'set -e
 
 echo
 if [ -z "$LLAMACPP_BIN$VLLM_BIN$SGLANG_PYTHON" ]; then
-  say "no engine paths given; this node can only run the 'sim' engine until"
-  say "one is installed and the configuration points at it"
+  say "the agent now installs the engines the control plane asks for: the"
+  say "build for this machine, checked against its publisher's checksum and run"
+  say "before the node is offered any model. 'llmgw ctl nodes' shows progress."
 fi
 if [ -n "$ENGINE_PROBLEMS" ]; then
   echo "$NODE is onboarded but an engine will not run:$ENGINE_PROBLEMS"

deploy/examples/agent.yaml

@@ -84,6 +84,15 @@ discovery:
 #   - /var/lib/llmgw-models
 #   - /mnt/lustre/models
 
+# The agent installs the engines the control plane names (see `engines:` in
+# server.yaml) under /opt/llmgw/engines: the build for this machine — CUDA when
+# an NVIDIA driver is loaded — checked against its publisher's checksum, with
+# the OS packages it needs, and run before the node takes any model. llama.cpp
+# is installed this way today. Naming a binary below opts that engine out and
+# uses yours instead; vLLM and SGLang still have to be named until the agent
+# installs them too.
+# engines_dir: /opt/llmgw/engines
+
 engines:
   vllm:
     bin: /opt/venvs/vllm/bin/vllm

deploy/examples/server.yaml

@@ -197,6 +197,13 @@ router:
     session_load_factor: 1.25
 
 # How aggressively the control plane reconciles.
+# The engines every node installs, and at which version. Unset keeps the
+# versions this release was checked against (llama.cpp b10991). Each agent
+# picks the build for its own hardware and installs it itself; changing a
+# version here reaches every node on its next connect.
+# engines:
+#   llamacpp: b10991
+
 control:
   interval: 5s
   base_backoff: 10s

docs/reference.md

@@ -54,6 +54,7 @@ rather than repeated.
 | `adopt_ready_timeout` | `time.Duration` | [Config](#config) |
 | `tls` | `tlsconf.Config` | [Config](#config) |
 | `model_dirs` | `[]string` | [Config](#config) |
+| `engines_dir` | `string` | [Config](#config) |
 | `weights_cache` | `string` | [Config](#config) |
 | `discovery` | `discovery.Options` | [Config](#config) |
 | `engines` | `engines.Config` | [Config](#config) |
@@ -160,6 +161,7 @@ rather than repeated.
 | `agent_tls` | `tlsconf.Config` | [Server](#server) |
 | `monitoring` | `Monitoring` | [Server](#server) |
 | `mirror` | `Mirror` | [Server](#server) |
+| `engines` | `map[string]string` | [Server](#server) |
 | `router` | `Router` | [Server](#server) |
 | `control` | `Control` | [Server](#server) |
 | `models` | `[]catalog.Model` | [Server](#server) |
@@ -432,6 +434,13 @@ exported over the fabric, local NVMe and a copy made by hand all look
 identical from here, and placement only needs to know whether the file
 is present.
 
+### `engines_dir`
+
+`string`
+
+EnginesDir is where the agent installs engines, one directory per
+build. Defaults to /opt/llmgw/engines.
+
 ### `weights_cache`
 
 `string`
@@ -589,8 +598,8 @@ know that this page cannot guess.
 
 Bin is the llama-server binary. It is the server, not the CLI: the
 gateway talks OpenAI over HTTP and needs the one that serves it.
-Empty looks on PATH, then where release archives are unpacked
-(/opt/llama.cpp).
+Empty means the agent installs llama.cpp itself, at the version the
+control plane asks for. Setting it opts out of that.
 
 ### `parallel`
 
@@ -1193,6 +1202,18 @@ Empty means there is none, and /admin/mirror stays unmounted.
 
 Takes a [Mirror](#mirror) block.
 
+### `engines`
+
+`map[string]string`
+
+Engines are the engines every node installs, and at which version. The
+agents install them themselves — the right build for their hardware,
+checked against its publisher's checksum and seen to run — so a node is
+never trusted to already have what somebody once put there.
+
+Unset keeps DefaultEngines. A version replaces the default; an empty
+one leaves that engine to be installed by hand.
+
 ### `router`
 
 `Router`

internal/agent/agent.go

@@ -28,6 +28,7 @@ import (
 	"gitea.mynodes.xyz/ilker/llmgw/api/gen/llmgw/v1/llmgwv1connect"
 	"gitea.mynodes.xyz/ilker/llmgw/internal/agent/discovery"
 	"gitea.mynodes.xyz/ilker/llmgw/internal/agent/engines"
+	"gitea.mynodes.xyz/ilker/llmgw/internal/agent/provision"
 	"gitea.mynodes.xyz/ilker/llmgw/internal/agent/supervisor"
 	"gitea.mynodes.xyz/ilker/llmgw/internal/agent/weights"
 	"gitea.mynodes.xyz/ilker/llmgw/internal/control/agentsvc"
@@ -94,6 +95,10 @@ type Config struct {
 	// is present.
 	ModelDirs []string `koanf:"model_dirs"`
 
+	// EnginesDir is where the agent installs engines, one directory per
+	// build. Defaults to /opt/llmgw/engines.
+	EnginesDir string `koanf:"engines_dir"`
+
 	// WeightsCache is where a remote source is downloaded to. Defaults to the
 	// first entry of ModelDirs, because a node that says where its models live
 	// has already answered this question, and otherwise to
@@ -304,16 +309,28 @@ type Agent struct {
 	reg  *engines.Registry
 	http connectHTTPClient
 
-	// engineOnce probes the installed engines once before registering.
+	// engineOnce probes the configured engines once before registering.
 	//
 	// Once, because probing SGLang imports it in a Python interpreter — seconds
 	// on a cold cache — and a reconnect is not a reason to pay that again.
-	// Later changes are found by the slower re-probe the heartbeat starts, not
-	// by registering again: an engine installed while the agent runs used to
-	// stay invisible until somebody thought to restart the agent.
+	// Later changes are found by the slower re-probe the heartbeat starts.
 	engineOnce sync.Once
-	// engineVers is guarded by mu once the first probe has run.
-	engineVers map[string]string
+	// configuredVers are the engines the configuration names and that answer.
+	// Guarded by mu once the first probe has run.
+	configuredVers map[string]string
+	// installedVers are the engines this agent installed and saw run.
+	// Guarded by mu.
+	installedVers map[string]string
+
+	// prov installs the engines the control plane asks for. provWants is what
+	// it asked for, nil until it has; provStatus is where each stands and
+	// provSent the fingerprint of what the control plane last heard. All
+	// guarded by mu. provKick starts a pass without waiting for the timer.
+	prov       *provision.Installer
+	provWants  []provision.Want
+	provStatus map[string]provision.Status
+	provSent   string
+	provKick   chan struct{}
 	// enginesSent is the fingerprint of the engines the control plane last
 	// heard about, from registration or a heartbeat. Guarded by mu.
 	enginesSent string
@@ -329,8 +346,9 @@ type Agent struct {
 	fetcher      *weights.Fetcher
 
 	// lastWeights is the fingerprint of the file list most recently sent, so a
-	// heartbeat carries the list only when it changed. Touched only by the
-	// heartbeat goroutine, which is the only thing that reads or writes it.
+	// heartbeat carries the list only when it changed. Guarded by mu: during a
+	// failover the old stream's heartbeat loop can still be running when the
+	// new one's starts.
 	lastWeights string
 
 	// fetchWatchers are the shards waiting on each source, so progress on one
@@ -363,12 +381,16 @@ func New(cfg Config, httpClient connectHTTPClient, log *slog.Logger) (*Agent, er
 	if err != nil {
 		return nil, err
 	}
-	return &Agent{
+	a := &Agent{
 		cfg: cfg, log: log, sup: sup,
 		reg:          engines.NewRegistry(cfg.Engines),
 		http:         httpClient,
 		shardReplica: map[string]string{},
-	}, nil
+		provStatus:   map[string]provision.Status{},
+		provKick:     make(chan struct{}, 1),
+	}
+	a.prov = &provision.Installer{Root: cfg.EnginesDir, Log: log, OnStatus: a.provisionStatus}
+	return a, nil
 }
 
 // Supervisor exposes the process supervisor, for tests and `ctl logs`.
@@ -387,6 +409,7 @@ func (a *Agent) Run(ctx context.Context) error {
 		a.log.Error("hardware discovery failed", "err", err)
 	}
 	a.recoverOrphans()
+	go a.provisionLoop(ctx)
 
 	attempt := 0
 	next := 0
@@ -645,9 +668,13 @@ func (a *Agent) scan(ctx context.Context) error {
 	opts := a.cfg.Discovery
 	opts.ModelDirs = a.cfg.ModelDirs
 	inv, err := discovery.Discover(ctx, opts, a.log)
+	host := discovery.DiscoverHost()
 	a.mu.Lock()
 	a.inv = inv
+	a.prov.Host = host
 	a.mu.Unlock()
+	a.log.Info("this node", "os", host.OSID+" "+host.OSVersion, "arch", host.Arch,
+		"cpu_flags", host.CPUFlags, "nvidia_driver", host.NVIDIADriver)
 	return err
 }
 
@@ -685,7 +712,18 @@ func (a *Agent) session(ctx context.Context, server string) error {
 	// engine whether or not its binary exists, so without this a node with no
 	// vLLM accepted a vLLM shard and failed it minutes later.
 	reg.EngineVersions = a.engines(parent)
+	reg.EnginesProbed = true
 	reg.RunningShards = a.runningShards()
+	a.mu.Lock()
+	h := a.prov.Host
+	// A new stream is a control plane that knows nothing of where installs
+	// stand, so the next heartbeat tells it again.
+	a.provSent = ""
+	a.mu.Unlock()
+	reg.Host = &llmgwv1.Host{
+		OsId: h.OSID, OsVersion: h.OSVersion, OsCodename: h.OSCodename,
+		Arch: h.Arch, CpuFlags: h.CPUFlags, NvidiaDriver: h.NVIDIADriver,
+	}
 
 	if err := stream.Send(&llmgwv1.AgentMessage{
 		Msg: &llmgwv1.AgentMessage_Register{Register: reg},
@@ -780,10 +818,22 @@ func (a *Agent) heartbeat() *llmgwv1.AgentMessage {
 
 	a.reprobeEngines()
 	a.mu.Lock()
-	if fp := enginesFingerprint(a.engineVers); a.engineVers != nil && fp != a.enginesSent {
-		a.enginesSent = fp
+	if vers := a.engineReportLocked(); a.configuredVers != nil &&
+		enginesFingerprint(vers) != a.enginesSent {
+		a.enginesSent = enginesFingerprint(vers)
 		hb.EnginesChanged = true
-		hb.EngineVersions = maps.Clone(a.engineVers)
+		hb.EngineVersions = vers
+	}
+	if fp := provisionFingerprint(a.provStatus); fp != a.provSent {
+		a.provSent = fp
+		hb.ProvisionChanged = true
+		for _, e := range slices.Sorted(maps.Keys(a.provStatus)) {
+			st := a.provStatus[e]
+			hb.Provision = append(hb.Provision, &llmgwv1.ProvisionStatus{
+				Engine: st.Engine, Version: st.Version, Variant: st.Variant,
+				State: st.State, Detail: st.Detail,
+			})
+		}
 	}
 	a.mu.Unlock()
 
@@ -807,8 +857,12 @@ func (a *Agent) heartbeat() *llmgwv1.AgentMessage {
 	// rather than "nothing to report" — without it, the first heartbeat after
 	// a model was deleted would be indistinguishable from silence.
 	weights := discovery.ScanWeights(a.cfg.ModelDirs)
-	if fp := weightsFingerprint(weights); fp != a.lastWeights {
-		a.lastWeights = fp
+	fp := weightsFingerprint(weights)
+	a.mu.Lock()
+	changed := fp != a.lastWeights
+	a.lastWeights = fp
+	a.mu.Unlock()
+	if changed {
 		hb.WeightsChanged = true
 		for _, w := range weights {
 			hb.Weights = append(hb.Weights, &llmgwv1.LocalWeights{
@@ -899,6 +953,8 @@ func (a *Agent) handle(ctx context.Context, msg *llmgwv1.ControlMessage, out cha
 		}
 	case *llmgwv1.ControlMessage_RemoveWeights:
 		a.removeWeights(m.RemoveWeights.GetPaths())
+	case *llmgwv1.ControlMessage_Provision:
+		a.setProvision(m.Provision)
 	case *llmgwv1.ControlMessage_Ack:
 		if !m.Ack.GetOk() {
 			a.log.Warn("control plane rejected a message",
@@ -1152,27 +1208,129 @@ func Client(cfg tlsconf.Config, timeout time.Duration) (*http.Client, error) {
 	return &http.Client{Transport: &http2.Transport{TLSClientConfig: tc}}, nil
 }
 
-// engines is what this node can run, probed once.
-//
-// Failures are silence rather than an error: an engine that is not installed is
-// the ordinary case on most nodes, and an agent that refused to register over
-// one would take a working node out of the fleet for a missing engine it was
-// never going to be asked to run.
+// engines is what this node can run: what the agent installed and saw run,
+// and what the configuration names and answers. Nothing merely found on the
+// machine — a llama-server on PATH is somebody's, not necessarily one that
+// works, and placing on it is how a replica fails on a node nobody watches.
 func (a *Agent) engines(ctx context.Context) map[string]string {
 	a.engineOnce.Do(func() {
-		vers := a.reg.Probe(ctx)
+		vers := a.reg.ProbeConfigured(ctx)
 		a.mu.Lock()
-		a.engineVers, a.lastEngineProbe = vers, time.Now()
+		a.configuredVers, a.lastEngineProbe = vers, time.Now()
 		a.mu.Unlock()
-		a.log.Info("engines available on this node",
-			"engines", engines.ProbedNames(vers))
+		if len(vers) > 0 {
+			a.log.Info("engines named in the configuration",
+				"engines", engines.ProbedNames(vers))
+		}
 	})
 	a.mu.Lock()
 	defer a.mu.Unlock()
+	vers := a.engineReportLocked()
 	// Whatever registration sends is what the control plane now knows, so a
 	// heartbeat repeats it only once it differs.
-	a.enginesSent = enginesFingerprint(a.engineVers)
-	return maps.Clone(a.engineVers)
+	a.enginesSent = enginesFingerprint(vers)
+	return vers
+}
+
+// engineReportLocked merges the two sources. Installed wins: it is the one
+// that was seen to run. Called with mu held.
+func (a *Agent) engineReportLocked() map[string]string {
+	out := maps.Clone(a.configuredVers)
+	if out == nil {
+		out = map[string]string{}
+	}
+	maps.Copy(out, a.installedVers)
+	return out
+}
+
+// provisionEvery is how often installed engines are checked again. A library
+// removed by an unrelated upgrade is found here rather than by the next
+// replica to start.
+const provisionEvery = 10 * time.Minute
+
+// setProvision takes the control plane's list of wanted engines.
+func (a *Agent) setProvision(p *llmgwv1.Provision) {
+	wants := []provision.Want{}
+	for _, e := range p.GetEngines() {
+		wants = append(wants, provision.Want{Engine: e.GetEngine(), Version: e.GetVersion()})
+	}
+	a.mu.Lock()
+	a.provWants = wants
+	a.mu.Unlock()
+	select {
+	case a.provKick <- struct{}{}:
+	default:
+	}
+}
+
+// provisionLoop installs and re-checks the wanted engines, one pass at a time.
+func (a *Agent) provisionLoop(ctx context.Context) {
+	t := time.NewTicker(provisionEvery)
+	defer t.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-a.provKick:
+		case <-t.C:
+		}
+		a.mu.Lock()
+		wants := slices.Clone(a.provWants)
+		managed := a.provWants != nil
+		a.mu.Unlock()
+		if !managed {
+			continue
+		}
+
+		statuses := a.prov.Converge(ctx, wants)
+		installed := map[string]string{}
+		keep := map[string]bool{}
+		for _, st := range statuses {
+			keep[st.Engine] = true
+			if st.State == provision.Ready {
+				a.reg.UseInstalled(st.Engine, st.Binary)
+				installed[st.Engine] = st.Version
+			}
+		}
+		a.mu.Lock()
+		if enginesFingerprint(installed) != enginesFingerprint(a.installedVers) {
+			a.log.Info("engines installed and running", "engines", engines.ProbedNames(installed))
+		}
+		a.installedVers = installed
+		// An engine no longer asked for is no longer reported on.
+		for e := range a.provStatus {
+			if !keep[e] {
+				delete(a.provStatus, e)
+			}
+		}
+		a.mu.Unlock()
+	}
+}
+
+// provisionStatus records a change in one engine's installation.
+func (a *Agent) provisionStatus(st provision.Status) {
+	a.mu.Lock()
+	prev, had := a.provStatus[st.Engine]
+	a.provStatus[st.Engine] = st
+	a.mu.Unlock()
+	if !had || prev.State != st.State || prev.Detail != st.Detail {
+		lvl := slog.LevelInfo
+		if st.State == provision.Failed || st.State == provision.Unsupported {
+			lvl = slog.LevelWarn
+		}
+		a.log.Log(context.Background(), lvl, "engine installation",
+			"engine", st.Engine, "version", st.Version, "variant", st.Variant,
+			"state", st.State, "detail", st.Detail)
+	}
+}
+
+func provisionFingerprint(m map[string]provision.Status) string {
+	var b strings.Builder
+	for _, k := range slices.Sorted(maps.Keys(m)) {
+		st := m[k]
+		fmt.Fprintf(&b, "%s|%s|%s|%s|%s\n", st.Engine, st.Version, st.Variant, st.State, st.Detail)
+	}
+	return b.String()
 }
 
 // engineReprobe is how often the installed engines are looked for again.
@@ -1198,14 +1356,14 @@ func (a *Agent) reprobeEngines() {
 	go func() {
 		ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 		defer cancel()
-		vers := a.reg.Probe(ctx)
+		vers := a.reg.ProbeConfigured(ctx)
 
 		a.mu.Lock()
-		changed := enginesFingerprint(vers) != enginesFingerprint(a.engineVers)
-		a.engineVers, a.lastEngineProbe, a.probingEngines = vers, time.Now(), false
+		changed := enginesFingerprint(vers) != enginesFingerprint(a.configuredVers)
+		a.configuredVers, a.lastEngineProbe, a.probingEngines = vers, time.Now(), false
 		a.mu.Unlock()
 		if changed {
-			a.log.Info("engines available on this node changed",
+			a.log.Info("engines named in the configuration changed",
 				"engines", engines.ProbedNames(vers))
 		}
 	}()

internal/agent/discovery/host.go

@@ -0,0 +1,154 @@
+package discovery
+
+import (
+	"bufio"
+	"os"
+	"runtime"
+	"strings"
+)
+
+// Host is what a node is, as far as installing software on it is concerned.
+type Host struct {
+	// OSID, OSVersion and OSCodename come from /etc/os-release: "ubuntu",
+	// "24.04", "noble".
+	OSID       string `json:"os_id,omitempty"`
+	OSVersion  string `json:"os_version,omitempty"`
+	OSCodename string `json:"os_codename,omitempty"`
+	// OSLike is ID_LIKE: the families this system says it follows, "debian"
+	// for Ubuntu, "rhel centos fedora" for Rocky. It is what decides the
+	// package manager, which the name alone does not for every derivative.
+	OSLike []string `json:"os_like,omitempty"`
+	// Arch is Debian's spelling, "amd64" or "arm64", because that is what
+	// package names and release archives are keyed by.
+	Arch string `json:"arch,omitempty"`
+	// CPUFlags are the vector extensions inference cares about, of those this
+	// processor has.
+	CPUFlags []string `json:"cpu_flags,omitempty"`
+	// NVIDIADriver is the loaded driver's version, empty when there is none.
+	NVIDIADriver string `json:"nvidia_driver,omitempty"`
+}
+
+// Family is the packaging family: "deb", "rpm", or "" when neither is known.
+func (h Host) Family() string {
+	for _, id := range append([]string{h.OSID}, h.OSLike...) {
+		switch id {
+		case "debian", "ubuntu":
+			return "deb"
+		case "rhel", "fedora", "centos", "rocky", "almalinux", "suse", "opensuse":
+			return "rpm"
+		}
+	}
+	return ""
+}
+
+// HasCPUFlag reports whether the processor has an extension.
+func (h Host) HasCPUFlag(f string) bool {
+	for _, have := range h.CPUFlags {
+		if have == f {
+			return true
+		}
+	}
+	return false
+}
+
+// interestingFlags are the extensions that decide which build of an engine
+// runs well. A VM on QEMU's default CPU model has none of them — and still
+// runs, five times slower, with nothing saying why.
+var interestingFlags = []string{"avx", "avx2", "fma", "f16c", "avx512f", "avx512_bf16", "amx_tile", "asimd", "sve"}
+
+// DiscoverHost reads what the machine is.
+func DiscoverHost() Host {
+	h := hostFromOSRelease("/etc/os-release")
+	h.Arch = debianArch(runtime.GOARCH)
+	h.CPUFlags = cpuFlagsFrom("/proc/cpuinfo")
+	h.NVIDIADriver = nvidiaDriverFrom("/proc/driver/nvidia/version")
+	return h
+}
+
+func hostFromOSRelease(path string) Host {
+	var h Host
+	f, err := os.Open(path) //nolint:gosec // a fixed system path
+	if err != nil {
+		return h
+	}
+	defer f.Close()
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		k, v, ok := strings.Cut(sc.Text(), "=")
+		if !ok {
+			continue
+		}
+		v = strings.Trim(v, `"'`)
+		switch k {
+		case "ID":
+			h.OSID = v
+		case "VERSION_ID":
+			h.OSVersion = v
+		case "VERSION_CODENAME":
+			h.OSCodename = v
+		case "ID_LIKE":
+			h.OSLike = strings.Fields(v)
+		}
+	}
+	return h
+}
+
+func debianArch(goarch string) string {
+	switch goarch {
+	case "amd64", "arm64":
+		return goarch
+	case "386":
+		return "i386"
+	case "arm":
+		return "armhf"
+	}
+	return goarch
+}
+
+func cpuFlagsFrom(path string) []string {
+	b, err := os.ReadFile(path) //nolint:gosec // a fixed system path
+	if err != nil {
+		return nil
+	}
+	have := map[string]bool{}
+	for _, line := range strings.Split(string(b), "\n") {
+		k, v, ok := strings.Cut(line, ":")
+		if !ok {
+			continue
+		}
+		// "flags" on x86, "Features" on ARM. The first processor is enough:
+		// a machine does not mix instruction sets across its cores.
+		if k = strings.TrimSpace(k); k != "flags" && k != "Features" {
+			continue
+		}
+		for _, f := range strings.Fields(v) {
+			have[f] = true
+		}
+		break
+	}
+	var out []string
+	for _, f := range interestingFlags {
+		if have[f] {
+			out = append(out, f)
+		}
+	}
+	return out
+}
+
+// nvidiaDriverFrom reads the loaded kernel module's version, which exists
+// exactly when a driver is loaded — unlike nvidia-smi, which can be installed
+// on a machine whose module failed to load.
+func nvidiaDriverFrom(path string) string {
+	b, err := os.ReadFile(path) //nolint:gosec // a fixed system path
+	if err != nil {
+		return ""
+	}
+	// "NVRM version: NVIDIA UNIX x86_64 Kernel Module  570.86.15  Thu ..."
+	fields := strings.Fields(string(b))
+	for i, f := range fields {
+		if f == "Module" && i+1 < len(fields) {
+			return fields[i+1]
+		}
+	}
+	return ""
+}

internal/agent/engines/engine.go

@@ -151,6 +151,16 @@ func NewRegistry(cfg Config) *Registry {
 	return r
 }
 
+// UseInstalled points an engine at a build the agent installed, and reports
+// whether the engine takes one.
+func (r *Registry) UseInstalled(name, path string) bool {
+	u, ok := r.engines[name].(interface{ UseInstalled(string) })
+	if ok {
+		u.UseInstalled(path)
+	}
+	return ok
+}
+
 // Add registers an engine, replacing any engine of the same name.
 func (r *Registry) Add(e Engine) { r.engines[e.Name()] = e }
 

internal/agent/engines/llamacpp.go

@@ -3,19 +3,19 @@ package engines
 import (
 	"fmt"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"sort"
 	"strconv"
 	"strings"
+	"sync/atomic"
 )
 
 // LlamaCppConfig locates the llama.cpp installation.
 type LlamaCppConfig struct {
 	// Bin is the llama-server binary. It is the server, not the CLI: the
 	// gateway talks OpenAI over HTTP and needs the one that serves it.
-	// Empty looks on PATH, then where release archives are unpacked
-	// (/opt/llama.cpp).
+	// Empty means the agent installs llama.cpp itself, at the version the
+	// control plane asks for. Setting it opts out of that.
 	Bin string `koanf:"bin"`
 	// Parallel is how many requests a server handles at once, when a profile
 	// does not say. llama.cpp defaults to one, which would make every second
@@ -29,7 +29,10 @@ type LlamaCppConfig struct {
 // small model on CPU at a speed that is fine for testing the whole path, and it
 // serves the same OpenAI API as the others, so nothing downstream can tell the
 // difference.
-type LlamaCpp struct{ cfg LlamaCppConfig }
+type LlamaCpp struct {
+	cfg       LlamaCppConfig
+	installed atomic.Pointer[string]
+}
 
 // Name identifies the engine in the catalog.
 func (*LlamaCpp) Name() string { return "llamacpp" }
@@ -170,33 +173,25 @@ func ggufIn(path string) (string, error) {
 	return filepath.Join(path, names[0]), nil
 }
 
-// llamaServerPlaces are where llama.cpp's release archives are unpacked when
-// they are not on PATH. The archive carries its shared libraries beside the
-// binary, so it is usually left in one directory rather than installed.
-var llamaServerPlaces = []string{
-	"/opt/llama.cpp/llama-server",
-	"/opt/llama.cpp/bin/llama-server",
-	"/opt/llama.cpp/build/bin/llama-server",
-	"/usr/local/llama.cpp/llama-server",
-}
+// UseInstalled points the engine at a build the agent installed and checked.
+// It takes precedence over everything else, because it is the only one that
+// was seen to run.
+func (l *LlamaCpp) UseInstalled(path string) { l.installed.Store(&path) }
 
-// bin is the llama-server to run: the configured one, else the one on PATH,
-// else the first of the usual unpack locations that exists.
-//
-// Found rather than required in the configuration, because every node here
-// had the same path written into its file by hand, and a node set up without
-// it reported no engine at all.
+// Configured reports whether the agent's configuration names a binary. A
+// named binary is the operator's deliberate choice; one merely found on PATH
+// is not, and is not reported as installed.
+func (l *LlamaCpp) Configured() bool { return l.cfg.Bin != "" }
+
+// bin is the llama-server to run: the installed build, else the configured
+// one, else whatever PATH has — which is only ever reached by a node not
+// provisioned by the agent and not told where its engine is.
 func (l *LlamaCpp) bin() string {
+	if p := l.installed.Load(); p != nil {
+		return *p
+	}
 	if l.cfg.Bin != "" {
 		return l.cfg.Bin
 	}
-	if p, err := exec.LookPath("llama-server"); err == nil {
-		return p
-	}
-	for _, p := range llamaServerPlaces {
-		if info, err := os.Stat(p); err == nil && !info.IsDir() && info.Mode()&0o111 != 0 {
-			return p
-		}
-	}
 	return "llama-server"
 }

internal/agent/engines/probe.go

@@ -157,11 +157,49 @@ func firstVersion(s string) string {
 	return Unknown
 }
 
+// Configured is an engine whose location the agent's configuration names.
+type Configured interface {
+	Configured() bool
+}
+
+// ProbeConfigured probes only the engines the configuration names.
+//
+// Probe looks everywhere — PATH, the default interpreter — and reports what
+// it finds, which is exactly the trust in whatever happens to be on a machine
+// that installing engines replaces. A node the agent provisions reports what
+// it installed, plus what the operator named on purpose; nothing else.
+func (r *Registry) ProbeConfigured(ctx context.Context) map[string]string {
+	out := map[string]string{}
+	for name, e := range r.engines {
+		c, ok := e.(Configured)
+		if !ok || !c.Configured() {
+			continue
+		}
+		p, ok := e.(Prober)
+		if !ok {
+			continue
+		}
+		if v, err := p.Probe(ctx); err == nil {
+			if v == "" {
+				v = Unknown
+			}
+			out[name] = v
+		}
+	}
+	return out
+}
+
 // Probe reports whether the llama.cpp server is installed.
 func (l *LlamaCpp) Probe(context.Context) (string, error) {
 	return installedBinary(l.bin())
 }
 
+// Configured reports whether the configuration names vLLM.
+func (v *VLLM) Configured() bool { return v.cfg.Bin != "" }
+
+// Configured reports whether the configuration names SGLang's interpreter.
+func (g *SGLang) Configured() bool { return g.cfg.Python != "" }
+
 // Probe reports whether vLLM is installed.
 func (v *VLLM) Probe(context.Context) (string, error) {
 	bin := v.cfg.Bin

internal/agent/provision/install.go

@@ -0,0 +1,614 @@
+package provision
+
+import (
+	"archive/tar"
+	"compress/gzip"
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"log/slog"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"gitea.mynodes.xyz/ilker/llmgw/internal/agent/discovery"
+)
+
+// Want is one engine at one version.
+type Want struct {
+	Engine  string
+	Version string
+}
+
+// The states an engine's installation can be in.
+const (
+	Installing  = "installing"
+	Ready       = "ready"
+	Failed      = "failed"
+	Unsupported = "unsupported"
+)
+
+// Status is where one engine's installation stands.
+type Status struct {
+	Engine  string
+	Version string
+	Variant string
+	State   string
+	// Detail is for a person: what is happening, or what went wrong.
+	Detail string
+	// Binary is the executable, once ready.
+	Binary string
+}
+
+// Installer installs engines under one directory.
+type Installer struct {
+	// Root is where engines are installed, one directory per build:
+	// <root>/<engine>/<version>-<variant>.
+	Root string
+	Host discovery.Host
+	Log  *slog.Logger
+	HTTP *http.Client
+	// OnStatus hears every change, so a download that takes minutes is seen
+	// to be under way rather than silent.
+	OnStatus func(Status)
+
+	// Run executes a command; a seam for tests. Nil runs it for real.
+	Run func(ctx context.Context, env []string, name string, args ...string) ([]byte, error)
+	// APIBase and DownloadBase default to GitHub; tests point them at a fake.
+	APIBase      string
+	DownloadBase string
+}
+
+// DefaultRoot is where engines are installed when nothing says otherwise.
+const DefaultRoot = "/opt/llmgw/engines"
+
+// marker is written into a build's directory once it has been installed and
+// seen to run. Its absence means the directory is not to be trusted.
+const marker = ".llmgw-installed"
+
+type markerFile struct {
+	Engine    string            `json:"engine"`
+	Version   string            `json:"version"`
+	Variant   string            `json:"variant"`
+	Binary    string            `json:"binary"`
+	SHA256    map[string]string `json:"sha256"`
+	Installed time.Time         `json:"installed"`
+}
+
+// Converge brings every wanted engine to ready, or says why it cannot.
+//
+// An engine already installed is checked again rather than believed: its
+// directory can be damaged, or a library it needs removed by somebody's
+// upgrade, and that is found here rather than by the next replica to fail.
+func (in *Installer) Converge(ctx context.Context, wants []Want) []Status {
+	out := make([]Status, 0, len(wants))
+	for _, w := range wants {
+		st := in.one(ctx, w)
+		in.report(st)
+		out = append(out, st)
+	}
+	return out
+}
+
+func (in *Installer) one(ctx context.Context, w Want) Status {
+	st := Status{Engine: w.Engine, Version: w.Version}
+	recipe, ok := Recipes[w.Engine]
+	if !ok {
+		st.State = Unsupported
+		st.Detail = "this agent does not know how to install " + w.Engine +
+			"; install it by hand and name it in the agent's configuration"
+		return st
+	}
+	build, err := recipe.Choose(w.Version, in.Host)
+	if err != nil {
+		st.State, st.Detail = Unsupported, err.Error()
+		return st
+	}
+	st.Variant = build.Variant
+	dir := filepath.Join(in.root(), w.Engine, w.Version+"-"+build.Variant)
+
+	// Installed before: check it still runs, and trust nothing else about it.
+	if _, err := os.Stat(filepath.Join(dir, marker)); err == nil {
+		// The packages are checked too. Removing one is exactly the kind of
+		// change an unrelated upgrade makes, and ldd below would catch it only
+		// as a missing library with no hint of which package held it.
+		if err := in.packages(ctx, build.Packages, &st); err != nil {
+			st.State, st.Detail = Failed, err.Error()
+			return st
+		}
+		bin, version, err := in.verify(ctx, dir, build)
+		if err == nil {
+			return in.ready(st, build, bin, version)
+		}
+		in.log().Warn("an installed engine no longer runs; installing it again",
+			"engine", w.Engine, "version", w.Version, "err", err)
+	}
+
+	if err := in.install(ctx, recipe, w, build, dir, &st); err != nil {
+		st.State, st.Detail, st.Binary = Failed, err.Error(), ""
+		return st
+	}
+	bin, version, err := in.verify(ctx, dir, build)
+	if err != nil {
+		st.State, st.Detail = Failed, err.Error()
+		return st
+	}
+	return in.ready(st, build, bin, version)
+}
+
+func (in *Installer) ready(st Status, b Build, bin, version string) Status {
+	st.State, st.Binary = Ready, bin
+	st.Detail = strings.TrimSpace(filepath.Base(bin) + " " + version)
+	var missing []string
+	for _, f := range b.CPUFlags {
+		if !in.Host.HasCPUFlag(f) {
+			missing = append(missing, f)
+		}
+	}
+	if len(missing) > 0 {
+		// Said on every report, not once in a log: it is the difference between
+		// five tokens a second and forty, and a VM given QEMU's default CPU
+		// model looks entirely healthy otherwise.
+		st.Detail += "; this CPU lacks " + strings.Join(missing, ", ") +
+			", so it will run several times slower (a VM needs CPU type \"host\")"
+	}
+	return st
+}
+
+// install fetches, checks and unpacks a build into dir.
+//
+// Into a scratch directory renamed into place at the end, so a failure halfway
+// leaves nothing that looks installed.
+func (in *Installer) install(ctx context.Context, r Recipe, w Want, b Build, dir string, st *Status) error {
+	if err := in.packages(ctx, b.Packages, st); err != nil {
+		return err
+	}
+
+	in.progress(st, "asking GitHub for the checksums of %s %s", w.Engine, w.Version)
+	sums, err := in.checksums(ctx, r.Repo, w.Version)
+	if err != nil {
+		return err
+	}
+
+	tmp := dir + ".partial"
+	_ = os.RemoveAll(tmp)
+	if err := os.MkdirAll(tmp, 0o755); err != nil {
+		return err
+	}
+	defer os.RemoveAll(tmp) //nolint:errcheck // gone either way once renamed
+
+	got := map[string]string{}
+	for _, asset := range b.Assets {
+		want, ok := sums[asset]
+		if !ok {
+			// Refused rather than installed unchecked: this is a binary that
+			// will run as root on every node.
+			return fmt.Errorf("%s %s publishes no checksum for %s, so it cannot be verified",
+				w.Engine, w.Version, asset)
+		}
+		archive := filepath.Join(tmp, asset+".download")
+		if err := in.download(ctx, r.Repo, w.Version, asset, archive, want, st); err != nil {
+			return err
+		}
+		in.progress(st, "unpacking %s", asset)
+		if err := untarGz(archive, tmp); err != nil {
+			return fmt.Errorf("unpacking %s: %w", asset, err)
+		}
+		_ = os.Remove(archive)
+		got[asset] = want
+	}
+
+	in.progress(st, "checking that %s runs", b.Binary)
+	bin, _, err := in.verify(ctx, tmp, b)
+	if err != nil {
+		return err
+	}
+	rel, _ := filepath.Rel(tmp, bin)
+	m, _ := json.MarshalIndent(markerFile{
+		Engine: w.Engine, Version: w.Version, Variant: b.Variant,
+		Binary: rel, SHA256: got, Installed: time.Now().UTC(),
+	}, "", "  ")
+	if err := os.WriteFile(filepath.Join(tmp, marker), m, 0o644); err != nil { //nolint:gosec // not secret
+		return err
+	}
+	_ = os.RemoveAll(dir)
+	if err := os.Rename(tmp, dir); err != nil {
+		return err
+	}
+	in.log().Info("installed an engine", "engine", w.Engine, "version", w.Version,
+		"variant", b.Variant, "dir", dir)
+	return nil
+}
+
+// verify finds the binary and runs it.
+//
+// Two checks, because they fail differently. ldd names a missing library
+// outright, where running the binary would only say it could not start. And
+// running it is the only proof that the rest — the right instruction set, the
+// right driver — is in place.
+func (in *Installer) verify(ctx context.Context, dir string, b Build) (bin, version string, err error) {
+	bin, err = findFile(dir, b.Binary)
+	if err != nil {
+		return "", "", err
+	}
+	if out, err := in.run(ctx, nil, "ldd", bin); err == nil {
+		if missing := lddMissing(string(out)); len(missing) > 0 {
+			return "", "", fmt.Errorf("%s cannot run on this system: %s", b.Binary, strings.Join(missing, "; "))
+		}
+	}
+	tctx, cancel := context.WithTimeout(ctx, 60*time.Second)
+	defer cancel()
+	out, err := in.run(tctx, nil, bin, "--version")
+	if err != nil {
+		return "", "", fmt.Errorf("%s --version failed: %v: %s", b.Binary, err, lastLine(out))
+	}
+	return bin, firstVersionLine(out), nil
+}
+
+// packages installs the operating system packages a build needs.
+//
+// Only those missing, and from the node's own package sources: a package the
+// system already has is not touched, so an engine never upgrades something
+// the rest of the machine depends on.
+func (in *Installer) packages(ctx context.Context, byFamily map[string][]string, st *Status) error {
+	family := in.Host.Family()
+	pkgs := byFamily[family]
+	if len(pkgs) == 0 {
+		// A system of no family this knows is not refused: its packages may
+		// well be there, and if they are not, ldd names the missing library.
+		return nil
+	}
+	pm := packageManagers[family]
+	var missing []string
+	for _, p := range pkgs {
+		if _, err := in.run(ctx, nil, pm.query[0], append(pm.query[1:], p)...); err != nil {
+			missing = append(missing, p)
+		}
+	}
+	if len(missing) == 0 {
+		return nil
+	}
+	tool, cmds := pm.install(in, missing)
+	if tool == "" {
+		return fmt.Errorf("%s is missing and no package manager was found to install it",
+			strings.Join(missing, ", "))
+	}
+	in.progress(st, "installing %s with %s", strings.Join(missing, ", "), tool)
+	for _, c := range cmds {
+		if out, err := in.run(ctx, pm.env, c[0], c[1:]...); err != nil {
+			return fmt.Errorf("%s: %v: %s", strings.Join(c, " "), err, lastLine(out))
+		}
+	}
+	return nil
+}
+
+// packageManager is how one packaging family asks and installs.
+type packageManager struct {
+	// query exits zero when the package named after it is installed.
+	query []string
+	env   []string
+	// install picks the tool present on this machine and the commands to run.
+	install func(in *Installer, pkgs []string) (tool string, cmds [][]string)
+}
+
+var packageManagers = map[string]packageManager{
+	"deb": {
+		// dpkg -s exits zero for a package merely known about, so the status
+		// is asked for and checked by the command itself: ${db:Status-Abbrev}
+		// is "ii " only when installed.
+		query: []string{"sh", "-c", `test "$(dpkg-query -W -f='${db:Status-Abbrev}' "$0" 2>/dev/null)" = "ii "`},
+		env:   []string{"DEBIAN_FRONTEND=noninteractive"},
+		install: func(_ *Installer, pkgs []string) (string, [][]string) {
+			// A lock timeout rather than failing on the lock: a machine a
+			// minute old is running cloud-init's and unattended-upgrades' own
+			// apt, and the first attempt on every new node would fail.
+			lock := "-o=DPkg::Lock::Timeout=600"
+			return "apt-get", [][]string{
+				{"apt-get", lock, "update"},
+				append([]string{"apt-get", lock, "install", "-y", "--no-install-recommends"}, pkgs...),
+			}
+		},
+	},
+	"rpm": {
+		query: []string{"rpm", "-q"},
+		install: func(in *Installer, pkgs []string) (string, [][]string) {
+			for _, tool := range []string{"dnf", "yum"} {
+				if in.has(tool) {
+					return tool, [][]string{append([]string{tool, "install", "-y"}, pkgs...)}
+				}
+			}
+			if in.has("zypper") {
+				return "zypper", [][]string{append([]string{"zypper", "--non-interactive", "install"}, pkgs...)}
+			}
+			return "", nil
+		},
+	},
+}
+
+// has reports whether a command is on PATH. Asked through the same seam as
+// every other command, so a test can say which tools a machine has.
+func (in *Installer) has(tool string) bool {
+	_, err := in.run(context.Background(), nil, "sh", "-c", `command -v "$0"`, tool)
+	return err == nil
+}
+
+// checksums reads the sha256 GitHub publishes for each asset of a release.
+func (in *Installer) checksums(ctx context.Context, repo, tag string) (map[string]string, error) {
+	url := strings.TrimSuffix(in.apiBase(), "/") + "/repos/" + repo + "/releases/tags/" + tag
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Accept", "application/vnd.github+json")
+	resp, err := in.client().Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("reaching GitHub for %s %s: %w", repo, tag, err)
+	}
+	defer resp.Body.Close()
+	switch {
+	case resp.StatusCode == http.StatusNotFound:
+		return nil, fmt.Errorf("%s has no release %s", repo, tag)
+	case resp.StatusCode == http.StatusForbidden || resp.StatusCode == http.StatusTooManyRequests:
+		// Unauthenticated callers get sixty requests an hour per address, and
+		// a whole fleet behind one NAT shares them.
+		return nil, fmt.Errorf("GitHub is rate-limiting this address (%s); it retries later", resp.Status)
+	case resp.StatusCode != http.StatusOK:
+		return nil, fmt.Errorf("GitHub answered %s for %s %s", resp.Status, repo, tag)
+	}
+	var rel struct {
+		Assets []struct {
+			Name   string `json:"name"`
+			Digest string `json:"digest"`
+		} `json:"assets"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&rel); err != nil {
+		return nil, fmt.Errorf("reading %s %s from GitHub: %w", repo, tag, err)
+	}
+	out := map[string]string{}
+	for _, a := range rel.Assets {
+		if sum, ok := strings.CutPrefix(a.Digest, "sha256:"); ok && len(sum) == 64 {
+			out[a.Name] = sum
+		}
+	}
+	return out, nil
+}
+
+func (in *Installer) download(ctx context.Context, repo, tag, asset, dst, want string, st *Status) error {
+	url := strings.TrimSuffix(in.downloadBase(), "/") + "/" + repo + "/releases/download/" + tag + "/" + asset
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return err
+	}
+	resp, err := in.client().Do(req)
+	if err != nil {
+		return fmt.Errorf("downloading %s: %w", asset, err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("downloading %s: %s", asset, resp.Status)
+	}
+	if resp.ContentLength > 0 {
+		in.progress(st, "downloading %s (%d MB)", asset, resp.ContentLength>>20)
+	} else {
+		in.progress(st, "downloading %s", asset)
+	}
+	f, err := os.Create(dst) //nolint:gosec // inside the install root
+	if err != nil {
+		return err
+	}
+	h := sha256.New()
+	_, err = io.Copy(io.MultiWriter(f, h), resp.Body)
+	if cerr := f.Close(); err == nil {
+		err = cerr
+	}
+	if err != nil {
+		return fmt.Errorf("downloading %s: %w", asset, err)
+	}
+	if got := hex.EncodeToString(h.Sum(nil)); got != want {
+		return fmt.Errorf("%s does not match the checksum its publisher gave (got %s, expected %s)",
+			asset, got[:12], want[:12])
+	}
+	return nil
+}
+
+// untarGz unpacks an archive under dir, refusing anything that would land
+// outside it. A release archive is somebody else's file, and a path of
+// "../../etc/cron.d/x" in it would otherwise be written as root.
+func untarGz(archive, dir string) error {
+	f, err := os.Open(archive) //nolint:gosec // inside the install root
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	gz, err := gzip.NewReader(f)
+	if err != nil {
+		return err
+	}
+	tr := tar.NewReader(gz)
+	for {
+		h, err := tr.Next()
+		if errors.Is(err, io.EOF) {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+		target, err := within(dir, h.Name)
+		if err != nil {
+			return err
+		}
+		switch h.Typeflag {
+		case tar.TypeDir:
+			if err := os.MkdirAll(target, 0o755); err != nil {
+				return err
+			}
+		case tar.TypeReg:
+			if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
+				return err
+			}
+			out, err := os.OpenFile(target, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, fs.FileMode(h.Mode)&0o755) //nolint:gosec // checked above
+			if err != nil {
+				return err
+			}
+			if _, err := io.Copy(out, tr); err != nil { //nolint:gosec // a release archive, size bounded by its checksum
+				out.Close()
+				return err
+			}
+			if err := out.Close(); err != nil {
+				return err
+			}
+		case tar.TypeSymlink:
+			// Libraries are versioned through symlinks, and those are
+			// relative. One pointing anywhere else is refused.
+			if filepath.IsAbs(h.Linkname) {
+				return fmt.Errorf("%s links outside the archive", h.Name)
+			}
+			if _, err := within(dir, filepath.Join(filepath.Dir(h.Name), h.Linkname)); err != nil {
+				return fmt.Errorf("%s links outside the archive", h.Name)
+			}
+			if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
+				return err
+			}
+			_ = os.Remove(target)
+			if err := os.Symlink(h.Linkname, target); err != nil {
+				return err
+			}
+		default:
+			// Devices, FIFOs and hard links have no business in a release.
+		}
+	}
+}
+
+func within(dir, name string) (string, error) {
+	target := filepath.Join(dir, name) //nolint:gosec // checked on the next line
+	rel, err := filepath.Rel(dir, target)
+	if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) {
+		return "", fmt.Errorf("%s would unpack outside the install directory", name)
+	}
+	return target, nil
+}
+
+// lddMissing reads what ldd could not satisfy, in two shapes:
+//
+//	libgomp.so.1 => not found
+//	/lib64/libstdc++.so.6: version `GLIBCXX_3.4.30' not found (required by ...)
+//
+// The second is a system too old for the build — RHEL 9 against a build that
+// wants GCC 12's libstdc++ — and is said as such, rather than as a library
+// that is plainly there being "not found".
+func lddMissing(out string) []string {
+	seen := map[string]bool{}
+	var missing []string
+	for _, line := range strings.Split(out, "\n") {
+		line = strings.TrimSpace(line)
+		if !strings.Contains(line, "not found") {
+			continue
+		}
+		var what string
+		if lib, rest, ok := strings.Cut(line, ": version `"); ok {
+			sym, _, _ := strings.Cut(rest, "'")
+			what = filepath.Base(lib) + " is too old (needs " + sym + ")"
+		} else {
+			what = strings.TrimSpace(strings.SplitN(line, "=>", 2)[0]) + " is not installed"
+		}
+		if !seen[what] {
+			seen[what] = true
+			missing = append(missing, what)
+		}
+	}
+	return missing
+}
+
+func findFile(dir, name string) (string, error) {
+	var found string
+	_ = filepath.WalkDir(dir, func(p string, d fs.DirEntry, err error) error {
+		if err != nil || found != "" {
+			return nil //nolint:nilerr // an unreadable subtree is not the binary
+		}
+		if !d.IsDir() && d.Name() == name {
+			found = p
+		}
+		return nil
+	})
+	if found == "" {
+		return "", fmt.Errorf("the build has no %s in it", name)
+	}
+	return found, nil
+}
+
+func (in *Installer) progress(st *Status, format string, args ...any) {
+	st.State, st.Detail = Installing, fmt.Sprintf(format, args...)
+	in.report(*st)
+}
+
+func (in *Installer) report(st Status) {
+	if in.OnStatus != nil {
+		in.OnStatus(st)
+	}
+}
+
+func (in *Installer) run(ctx context.Context, env []string, name string, args ...string) ([]byte, error) {
+	if in.Run != nil {
+		return in.Run(ctx, env, name, args...)
+	}
+	cmd := exec.CommandContext(ctx, name, args...) //nolint:gosec // fixed commands and paths we installed
+	cmd.Env = append(os.Environ(), env...)
+	return cmd.CombinedOutput()
+}
+
+func (in *Installer) root() string {
+	if in.Root != "" {
+		return in.Root
+	}
+	return DefaultRoot
+}
+
+func (in *Installer) log() *slog.Logger {
+	if in.Log != nil {
+		return in.Log
+	}
+	return slog.Default()
+}
+
+func (in *Installer) client() *http.Client {
+	if in.HTTP != nil {
+		return in.HTTP
+	}
+	return &http.Client{Timeout: 30 * time.Minute}
+}
+
+func (in *Installer) apiBase() string {
+	if in.APIBase != "" {
+		return in.APIBase
+	}
+	return "https://api.github.com"
+}
+
+func (in *Installer) downloadBase() string {
+	if in.DownloadBase != "" {
+		return in.DownloadBase
+	}
+	return "https://github.com"
+}
+
+func lastLine(b []byte) string {
+	lines := strings.Split(strings.TrimSpace(string(b)), "\n")
+	return strings.TrimSpace(lines[len(lines)-1])
+}
+
+func firstVersionLine(b []byte) string {
+	for _, l := range strings.Split(string(b), "\n") {
+		if strings.Contains(strings.ToLower(l), "version") {
+			return strings.TrimSpace(l)
+		}
+	}
+	return ""
+}

internal/agent/provision/install_test.go

@@ -0,0 +1,302 @@
+package provision
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"testing"
+
+	"gitea.mynodes.xyz/ilker/llmgw/internal/agent/discovery"
+)
+
+var ubuntu = discovery.Host{OSID: "ubuntu", OSVersion: "24.04", Arch: "amd64", CPUFlags: []string{"avx2"}}
+
+// release is a fake GitHub: one release, its assets and their digests.
+type release struct {
+	assets  map[string][]byte
+	digests map[string]string
+	gets    int
+	mu      sync.Mutex
+}
+
+func tarGz(t *testing.T, files map[string]string, links map[string]string) []byte {
+	t.Helper()
+	var buf bytes.Buffer
+	gz := gzip.NewWriter(&buf)
+	tw := tar.NewWriter(gz)
+	for name, body := range files {
+		_ = tw.WriteHeader(&tar.Header{Name: name, Mode: 0o755, Size: int64(len(body)), Typeflag: tar.TypeReg})
+		_, _ = tw.Write([]byte(body))
+	}
+	for name, target := range links {
+		_ = tw.WriteHeader(&tar.Header{Name: name, Linkname: target, Typeflag: tar.TypeSymlink})
+	}
+	_ = tw.Close()
+	_ = gz.Close()
+	return buf.Bytes()
+}
+
+func (r *release) serve(t *testing.T) *httptest.Server {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		r.mu.Lock()
+		r.gets++
+		r.mu.Unlock()
+		if strings.HasPrefix(req.URL.Path, "/repos/") {
+			var out struct {
+				Assets []map[string]string `json:"assets"`
+			}
+			for name := range r.assets {
+				out.Assets = append(out.Assets, map[string]string{"name": name, "digest": r.digests[name]})
+			}
+			_ = json.NewEncoder(w).Encode(out)
+			return
+		}
+		body, ok := r.assets[filepath.Base(req.URL.Path)]
+		if !ok {
+			http.NotFound(w, req)
+			return
+		}
+		_, _ = w.Write(body)
+	}))
+	t.Cleanup(srv.Close)
+	return srv
+}
+
+func newRelease(assets map[string][]byte) *release {
+	r := &release{assets: assets, digests: map[string]string{}}
+	for name, b := range assets {
+		sum := sha256.Sum256(b)
+		r.digests[name] = "sha256:" + hex.EncodeToString(sum[:])
+	}
+	return r
+}
+
+// fakeSystem answers the package tools, ldd and the engine itself.
+type fakeSystem struct {
+	mu        sync.Mutex
+	installed map[string]bool
+	tools     map[string]bool
+	lddOut    string
+	calls     []string
+}
+
+var errExit = errors.New("exit 1")
+
+func (f *fakeSystem) run(_ context.Context, _ []string, name string, args ...string) ([]byte, error) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.calls = append(f.calls, name+" "+strings.Join(args, " "))
+	switch {
+	case name == "sh" && strings.Contains(args[1], "dpkg-query"),
+		name == "rpm" && args[0] == "-q":
+		if f.installed[args[len(args)-1]] {
+			return nil, nil
+		}
+		return nil, errExit
+	case name == "sh" && strings.Contains(args[1], "command -v"):
+		if f.tools[args[2]] {
+			return nil, nil
+		}
+		return nil, errExit
+	case name == "apt-get" || name == "dnf":
+		for i, a := range args {
+			if a == "install" {
+				for _, p := range args[i+1:] {
+					if !strings.HasPrefix(p, "-") {
+						f.installed[p] = true
+					}
+				}
+			}
+		}
+		return nil, nil
+	case name == "ldd":
+		return []byte(f.lddOut), nil
+	case strings.HasSuffix(name, "llama-server"):
+		return []byte("version: 10991 (abc)\n"), nil
+	}
+	return nil, errors.New("unexpected command " + name)
+}
+
+func installer(t *testing.T, srv *httptest.Server, sys *fakeSystem, host discovery.Host) (*Installer, *[]Status) {
+	var seen []Status
+	var mu sync.Mutex
+	return &Installer{
+		Root: t.TempDir(), Host: host, Run: sys.run,
+		APIBase: srv.URL, DownloadBase: srv.URL, HTTP: srv.Client(),
+		OnStatus: func(s Status) { mu.Lock(); seen = append(seen, s); mu.Unlock() },
+	}, &seen
+}
+
+func llamaRelease(t *testing.T) *release {
+	return newRelease(map[string][]byte{
+		"llama-b1-bin-ubuntu-x64.tar.gz": tarGz(t,
+			map[string]string{"llama-b1/llama-server": "#!/bin/sh\n", "llama-b1/libllama.so.0": "x"},
+			map[string]string{"llama-b1/libllama.so": "libllama.so.0"}),
+	})
+}
+
+func TestAnEngineIsInstalledFromNothing(t *testing.T) {
+	// A node rebuilt from a bare image: no engine, no OpenMP runtime. What it
+	// ends with has to have come from the publisher, checked, and been run.
+	rel := llamaRelease(t)
+	sys := &fakeSystem{installed: map[string]bool{}}
+	in, seen := installer(t, rel.serve(t), sys, ubuntu)
+
+	got := in.Converge(t.Context(), []Want{{Engine: "llamacpp", Version: "b1"}})
+	if len(got) != 1 || got[0].State != Ready {
+		t.Fatalf("not ready: %+v", got)
+	}
+	if !sys.installed["libgomp1"] {
+		t.Error("the OpenMP runtime the build links against was not installed")
+	}
+	if !strings.HasPrefix(got[0].Binary, in.Root) {
+		t.Errorf("binary %s is not the one installed under %s", got[0].Binary, in.Root)
+	}
+	if _, err := os.Lstat(filepath.Join(filepath.Dir(got[0].Binary), "libllama.so")); err != nil {
+		t.Errorf("the library symlink was not unpacked: %v", err)
+	}
+	var states []string
+	for _, s := range *seen {
+		states = append(states, s.State+": "+s.Detail)
+	}
+	if !strings.Contains(strings.Join(states, "\n"), "downloading") {
+		t.Errorf("a download was not reported while it ran:\n%s", strings.Join(states, "\n"))
+	}
+}
+
+func TestAnInstalledEngineIsCheckedNotFetchedAgain(t *testing.T) {
+	rel := llamaRelease(t)
+	sys := &fakeSystem{installed: map[string]bool{}}
+	in, _ := installer(t, rel.serve(t), sys, ubuntu)
+	w := []Want{{Engine: "llamacpp", Version: "b1"}}
+	in.Converge(t.Context(), w)
+	before := rel.gets
+
+	got := in.Converge(t.Context(), w)
+	if got[0].State != Ready {
+		t.Fatalf("second pass: %+v", got[0])
+	}
+	if rel.gets != before {
+		t.Errorf("a ready engine was downloaded again (%d requests)", rel.gets-before)
+	}
+}
+
+func TestAnEngineThatCannotLoadALibraryIsNotReady(t *testing.T) {
+	// Found on a node before: llama-server present, executable, and unable to
+	// start for want of a library — while the node reported ready.
+	rel := llamaRelease(t)
+	sys := &fakeSystem{installed: map[string]bool{"libgomp1": true},
+		lddOut: "\tlibcuda.so.1 => not found\n"}
+	in, _ := installer(t, rel.serve(t), sys, ubuntu)
+
+	got := in.Converge(t.Context(), []Want{{Engine: "llamacpp", Version: "b1"}})
+	if got[0].State != Failed || !strings.Contains(got[0].Detail, "libcuda.so.1") {
+		t.Fatalf("expected a failure naming the library: %+v", got[0])
+	}
+	if _, err := os.Stat(filepath.Join(in.Root, "llamacpp", "b1-cpu", marker)); err == nil {
+		t.Error("a build that does not run was marked installed")
+	}
+}
+
+func TestADownloadThatDoesNotMatchItsChecksumIsRefused(t *testing.T) {
+	rel := llamaRelease(t)
+	for name := range rel.digests {
+		rel.digests[name] = "sha256:" + strings.Repeat("0", 64)
+	}
+	sys := &fakeSystem{installed: map[string]bool{"libgomp1": true}}
+	in, _ := installer(t, rel.serve(t), sys, ubuntu)
+
+	got := in.Converge(t.Context(), []Want{{Engine: "llamacpp", Version: "b1"}})
+	if got[0].State != Failed || !strings.Contains(got[0].Detail, "checksum") {
+		t.Fatalf("a tampered download was not refused: %+v", got[0])
+	}
+}
+
+func TestAnArchiveCannotWriteOutsideItsDirectory(t *testing.T) {
+	rel := newRelease(map[string][]byte{
+		"llama-b1-bin-ubuntu-x64.tar.gz": tarGz(t,
+			map[string]string{"../../escaped": "x", "llama-server": ""}, nil),
+	})
+	sys := &fakeSystem{installed: map[string]bool{"libgomp1": true}}
+	in, _ := installer(t, rel.serve(t), sys, ubuntu)
+
+	got := in.Converge(t.Context(), []Want{{Engine: "llamacpp", Version: "b1"}})
+	if got[0].State != Failed {
+		t.Fatalf("an archive escaping its directory was installed: %+v", got[0])
+	}
+}
+
+func TestTheBuildFollowsTheHardware(t *testing.T) {
+	gpu := ubuntu
+	gpu.NVIDIADriver = "570.86.15"
+	b, err := chooseLlamaCpp("b1", gpu)
+	if err != nil || !strings.HasPrefix(b.Variant, "cuda") || len(b.Assets) != 2 {
+		t.Errorf("an NVIDIA node got %+v, %v; expected the CUDA build and its runtime", b, err)
+	}
+	if _, err := chooseLlamaCpp("b1", discovery.Host{OSID: "ubuntu", Arch: "riscv64"}); err == nil {
+		t.Error("a build was chosen for an architecture llama.cpp does not publish for")
+	}
+
+	slow := ubuntu
+	slow.CPUFlags = nil
+	st := (&Installer{Host: slow}).ready(Status{}, Build{CPUFlags: []string{"avx2"}}, "/x/llama-server", "")
+	if !strings.Contains(st.Detail, "avx2") {
+		t.Errorf("a CPU without AVX2 was not called out: %q", st.Detail)
+	}
+}
+
+func TestAnEngineTheAgentCannotInstallSaysSo(t *testing.T) {
+	in := &Installer{Root: t.TempDir(), Host: ubuntu}
+	got := in.Converge(t.Context(), []Want{{Engine: "vllm", Version: "0.29.0"}})
+	if got[0].State != Unsupported {
+		t.Errorf("got %+v", got[0])
+	}
+}
+
+func TestARedHatFamilyNodeInstallsWithItsOwnPackageManager(t *testing.T) {
+	// The build is not Ubuntu's in any way that matters; the package that
+	// carries OpenMP's runtime is named differently, and installed by dnf.
+	rocky := discovery.Host{OSID: "rocky", OSVersion: "10.0", OSLike: []string{"rhel", "centos", "fedora"},
+		Arch: "amd64", CPUFlags: []string{"avx2"}}
+	rel := llamaRelease(t)
+	sys := &fakeSystem{installed: map[string]bool{}, tools: map[string]bool{"dnf": true}}
+	in, _ := installer(t, rel.serve(t), sys, rocky)
+
+	got := in.Converge(t.Context(), []Want{{Engine: "llamacpp", Version: "b1"}})
+	if got[0].State != Ready {
+		t.Fatalf("not ready: %+v", got[0])
+	}
+	if !sys.installed["libgomp"] || sys.installed["libgomp1"] {
+		t.Errorf("installed %v; expected the rpm name, libgomp", sys.installed)
+	}
+}
+
+func TestASystemTooOldForTheBuildSaysWhatItLacks(t *testing.T) {
+	// RHEL 9: glibc is new enough, libstdc++ is one GCC release short. ldd
+	// finds the library and reports the symbol, and "libstdc++ not found"
+	// would send somebody looking for a package that is installed.
+	rel := llamaRelease(t)
+	sys := &fakeSystem{installed: map[string]bool{"libgomp1": true},
+		lddOut: "\t/lib64/libstdc++.so.6: version `GLIBCXX_3.4.30' not found (required by /x/libllama.so)\n" +
+			"\t/lib64/libstdc++.so.6: version `GLIBCXX_3.4.30' not found (required by /x/llama-server)\n"}
+	in, _ := installer(t, rel.serve(t), sys, ubuntu)
+
+	got := in.Converge(t.Context(), []Want{{Engine: "llamacpp", Version: "b1"}})
+	if got[0].State != Failed || !strings.Contains(got[0].Detail, "libstdc++.so.6 is too old (needs GLIBCXX_3.4.30)") {
+		t.Fatalf("detail %q", got[0].Detail)
+	}
+	if strings.Count(got[0].Detail, "GLIBCXX") != 1 {
+		t.Errorf("the same shortfall was listed more than once: %q", got[0].Detail)
+	}
+}

internal/agent/provision/recipe.go

@@ -0,0 +1,109 @@
+// Package provision installs the engines a node is asked to have.
+//
+// The control plane says which engines at which versions; everything else is
+// worked out here, on the node, because only the node knows it: which build
+// fits its processor and driver, what its operating system is missing, and
+// whether the result actually runs. Nothing already on the machine is taken
+// on trust. An engine counts as installed when this package installed it,
+// checked every file against the checksum its publisher gave, and watched it
+// start.
+package provision
+
+import (
+	"fmt"
+	"strings"
+
+	"gitea.mynodes.xyz/ilker/llmgw/internal/agent/discovery"
+)
+
+// Build is one published build of an engine, chosen for one machine.
+type Build struct {
+	// Variant names the build: "cpu", "cuda-12.8".
+	Variant string
+	// Assets are the release files to fetch, unpacked in order into one
+	// directory.
+	Assets []string
+	// Packages are operating system packages the build links against and a
+	// minimal install may not carry, by packaging family ("deb", "rpm"): the
+	// same library is libgomp1 on one and libgomp on the other.
+	Packages map[string][]string
+	// Binary is the executable's file name, found anywhere in the unpacked
+	// tree.
+	Binary string
+	// CPUFlags are extensions the build is slow without. Missing ones are
+	// reported, not refused: slow is still running.
+	CPUFlags []string
+}
+
+// Recipe knows how to install one engine.
+type Recipe struct {
+	// Repo is the GitHub repository whose releases carry the builds.
+	Repo string
+	// Choose picks the build for a machine, or says why none fits.
+	Choose func(version string, h discovery.Host) (Build, error)
+}
+
+// Recipes are the engines this agent can install.
+//
+// vLLM and SGLang are not here yet: they are Python environments of several
+// gigabytes rather than an archive, and are installed by hand and named in the
+// agent's configuration until they are.
+var Recipes = map[string]Recipe{
+	"llamacpp": {Repo: "ggml-org/llama.cpp", Choose: chooseLlamaCpp},
+}
+
+// cudaForLlamaCpp is the CUDA build taken on an NVIDIA node. The release also
+// carries a matching cudart archive, so the node needs a driver and nothing
+// else — no toolkit.
+const cudaForLlamaCpp = "12.8"
+
+func chooseLlamaCpp(version string, h discovery.Host) (Build, error) {
+	// The published Linux builds are built on Ubuntu, but nothing about them
+	// is Ubuntu's: they need glibc 2.34 and the libstdc++ of GCC 12, which
+	// Debian 12 and RHEL 10 have and RHEL 9 does not. So the distribution's
+	// name decides nothing here. The build is tried everywhere, and ldd says
+	// whether this system can load it — in the words of the missing symbol.
+	var arch string
+	switch h.Arch {
+	case "amd64":
+		arch = "x64"
+	case "arm64":
+		arch = "arm64"
+	default:
+		return Build{}, fmt.Errorf("llama.cpp publishes no Linux build for %s", orUnknown(h.Arch))
+	}
+
+	b := Build{
+		Variant: "cpu",
+		Assets:  []string{fmt.Sprintf("llama-%s-bin-ubuntu-%s.tar.gz", version, arch)},
+		// Everything else the build links is in the archive or in any current
+		// glibc system; OpenMP's runtime is the one a cloud image lacks, and
+		// the server does not start without it.
+		Packages: map[string][]string{"deb": {"libgomp1"}, "rpm": {"libgomp"}},
+		Binary:   "llama-server",
+	}
+	if arch == "x64" {
+		// The archive carries a backend per CPU generation and loads the best
+		// one, down to SSE4.2. Below AVX2 it runs, several times slower.
+		b.CPUFlags = []string{"avx2"}
+	}
+	// The CUDA build is published for x64 at this version; on arm64 it is a
+	// newer CUDA that the driver may not support, so an arm64 GPU node runs
+	// the CPU build until someone decides otherwise.
+	if h.NVIDIADriver != "" && arch == "x64" {
+		name := fmt.Sprintf("bin-ubuntu-cuda-%s-x64.tar.gz", cudaForLlamaCpp)
+		b.Variant = "cuda-" + cudaForLlamaCpp
+		b.Assets = []string{
+			fmt.Sprintf("llama-%s-%s", version, name),
+			fmt.Sprintf("cudart-llama-%s-%s", version, name),
+		}
+	}
+	return b, nil
+}
+
+func orUnknown(s string) string {
+	if strings.TrimSpace(s) == "" {
+		return "an unrecognised system"
+	}
+	return s
+}

internal/agent/selfdescribe_test.go

@@ -1,9 +1,11 @@
 package agent
 
 import (
+	"context"
 	"os"
 	"slices"
 	"testing"
+	"time"
 
 	llmgwv1 "gitea.mynodes.xyz/ilker/llmgw/api/gen/llmgw/v1"
 )
@@ -60,15 +62,15 @@ func TestAHeartbeatSaysWhenTheEnginesChanged(t *testing.T) {
 	engines := func(m *llmgwv1.AgentMessage) *llmgwv1.Heartbeat { return m.GetHeartbeat() }
 
 	a.mu.Lock()
-	a.engineVers = map[string]string{"llamacpp": "unknown"}
-	a.enginesSent = enginesFingerprint(a.engineVers)
+	a.configuredVers = map[string]string{"llamacpp": "unknown"}
+	a.enginesSent = enginesFingerprint(a.configuredVers)
 	a.mu.Unlock()
 	if hb := engines(a.heartbeat()); hb.GetEnginesChanged() {
 		t.Errorf("unchanged engines were resent")
 	}
 
 	a.mu.Lock()
-	a.engineVers = map[string]string{"llamacpp": "unknown", "vllm": "unknown"}
+	a.configuredVers = map[string]string{"llamacpp": "unknown", "vllm": "unknown"}
 	a.mu.Unlock()
 	hb := engines(a.heartbeat())
 	if !hb.GetEnginesChanged() || len(hb.GetEngineVersions()) != 2 {
@@ -78,3 +80,40 @@ func TestAHeartbeatSaysWhenTheEnginesChanged(t *testing.T) {
 		t.Errorf("reported again on the next heartbeat")
 	}
 }
+
+func TestWhatTheControlPlaneAsksToInstallIsReportedBack(t *testing.T) {
+	cfg := Config{Server: "127.0.0.1:7443", NodeID: "n1", WeightsCache: t.TempDir(),
+		EnginesDir: t.TempDir()}
+	cfg.Superv.WorkDir = t.TempDir()
+	a, err := New(cfg, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ctx, cancel := context.WithCancel(t.Context())
+	defer cancel()
+	go a.provisionLoop(ctx)
+
+	// An engine this agent cannot install: no network is needed to learn so,
+	// and the answer has to reach the control plane rather than a log.
+	a.setProvision(&llmgwv1.Provision{Engines: []*llmgwv1.EngineWant{{Engine: "vllm", Version: "0.29.0"}}})
+
+	deadline := time.Now().Add(3 * time.Second)
+	for time.Now().Before(deadline) {
+		hb := a.heartbeat().GetHeartbeat()
+		if hb.GetProvisionChanged() {
+			p := hb.GetProvision()
+			if len(p) != 1 || p[0].GetState() != "unsupported" {
+				t.Fatalf("reported %v", p)
+			}
+			a.mu.Lock()
+			_, reported := a.engineReportLocked()["vllm"]
+			a.mu.Unlock()
+			if reported {
+				t.Error("an engine that was not installed is reported as present")
+			}
+			return
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	t.Fatal("the installation's outcome never reached a heartbeat")
+}

internal/cli/ctl.go

@@ -189,13 +189,27 @@ func newNodesCmd(client func() *ctlClient, asJSON *bool) *cobra.Command {
 			_ = w.Flush()
 
 			// Unhealthy GPUs are usually the answer when a node looks idle but
-			// nothing schedules onto it.
+			// nothing schedules onto it. An engine still installing, or one
+			// that failed to, is the other usual answer.
+			said := false
 			for _, n := range nodes {
 				for _, p := range n.Unhealthy {
 					fmt.Printf("\n%s: %s (kept out of placement)", n.ID, p)
+					said = true
+				}
+				for _, p := range n.Provision {
+					if p.State == "ready" {
+						continue
+					}
+					fmt.Printf("\n%s: %s %s %s: %s", n.ID, p.Engine, p.Version, p.State, p.Detail)
+					said = true
+				}
+				for _, w := range n.Warnings {
+					fmt.Printf("\n%s: %s", n.ID, w)
+					said = true
 				}
 			}
-			if hasUnhealthy(nodes) {
+			if said {
 				fmt.Println()
 			}
 			return nil
@@ -478,12 +492,3 @@ func dash(s string) string {
 	}
 	return s
 }
-
-func hasUnhealthy(nodes []adminapi.NodeView) bool {
-	for _, n := range nodes {
-		if len(n.Unhealthy) > 0 {
-			return true
-		}
-	}
-	return false
-}

internal/cli/server.go

@@ -401,6 +401,8 @@ func startControlPlane(ctx context.Context, cfg config.Server, cat *catalog.Live
 		}
 	}
 	svc := agentsvc.New(ctl.Inventory(), ctl.Reconciler(), requireIdentity, log)
+	svc.SetEngines(cfg.WantedEngines())
+	log.Info("nodes install these engines", "engines", cfg.WantedEngines())
 	// A standby must refuse agents as well as refusing to place. Commands
 	// travel down the stream the agent opened, so a standby holding one is a
 	// node the leader cannot command — and the leader's placements would fail

internal/config/config.go

@@ -72,6 +72,15 @@ type Server struct {
 	// Empty means there is none, and /admin/mirror stays unmounted.
 	Mirror Mirror `koanf:"mirror"`
 
+	// Engines are the engines every node installs, and at which version. The
+	// agents install them themselves — the right build for their hardware,
+	// checked against its publisher's checksum and seen to run — so a node is
+	// never trusted to already have what somebody once put there.
+	//
+	// Unset keeps DefaultEngines. A version replaces the default; an empty
+	// one leaves that engine to be installed by hand.
+	Engines map[string]string `koanf:"engines"`
+
 	Router  Router          `koanf:"router"`
 	Control Control         `koanf:"control"`
 	Models  []catalog.Model `koanf:"models"`
@@ -542,3 +551,25 @@ func (s Server) ControlPlaneMode() bool {
 	}
 	return false
 }
+
+// DefaultEngines are the engine versions this release was checked against:
+// `llmgw ctl engine-check` accepted every flag llmgw builds for them.
+var DefaultEngines = map[string]string{
+	"llamacpp": "b10991",
+}
+
+// WantedEngines is DefaultEngines with the configuration laid over it.
+func (s Server) WantedEngines() map[string]string {
+	out := map[string]string{}
+	for k, v := range DefaultEngines {
+		out[k] = v
+	}
+	for k, v := range s.Engines {
+		if v == "" {
+			delete(out, k)
+			continue
+		}
+		out[k] = v
+	}
+	return out
+}

internal/config/config_test.go

@@ -182,3 +182,20 @@ func TestAModelWithProfilesStillMakesAControlPlane(t *testing.T) {
 		t.Error("a declared model with profiles is still a control plane")
 	}
 }
+
+func TestEnginesDefaultToTheCheckedVersions(t *testing.T) {
+	var s Server
+	if got := s.WantedEngines()["llamacpp"]; got != DefaultEngines["llamacpp"] {
+		t.Errorf("unset config wants llamacpp %q", got)
+	}
+	s.Engines = map[string]string{"llamacpp": "b11000", "vllm": "0.29.0"}
+	got := s.WantedEngines()
+	if got["llamacpp"] != "b11000" || got["vllm"] != "0.29.0" {
+		t.Errorf("configured versions not taken: %v", got)
+	}
+	// Empty leaves an engine to be installed by hand.
+	s.Engines = map[string]string{"llamacpp": ""}
+	if _, ok := s.WantedEngines()["llamacpp"]; ok {
+		t.Error("an emptied engine is still wanted")
+	}
+}

internal/control/adminapi/api.go

@@ -13,6 +13,7 @@ import (
 	"io"
 	"net/http"
 	"slices"
+	"strings"
 	"time"
 
 	"gitea.mynodes.xyz/ilker/llmgw/internal/bench"
@@ -78,6 +79,15 @@ type NodeView struct {
 	// which is not the same as having none — placement treats it that way too,
 	// or a control plane upgrade would empty a fleet.
 	Engines []string `json:"engines,omitempty"`
+	// Provision is where installing each wanted engine stands. An engine is in
+	// Engines only once its installation here is ready.
+	Provision []inventory.EngineInstall `json:"provision,omitempty"`
+	// OS is the operating system and architecture, as the agent read them.
+	OS string `json:"os,omitempty"`
+	// Warnings are facts about the machine that make it slow or unusable
+	// without making it unhealthy: a VM with no vector instructions runs every
+	// model, at a fifth of the speed.
+	Warnings []string `json:"warnings,omitempty"`
 
 	// Models are the weights this node can see. Absent means it was not asked
 	// to look, which is not the same as holding none.
@@ -230,6 +240,14 @@ func (a *API) Nodes() []NodeView {
 			v.Engines = append(v.Engines, name)
 		}
 		slices.Sort(v.Engines)
+		v.Provision = n.Provision
+		if h := n.Host; h.OSID != "" {
+			v.OS = strings.TrimSpace(h.OSID + " " + h.OSVersion + " " + h.Arch)
+			if h.Arch == "amd64" && !h.HasCPUFlag("avx2") {
+				v.Warnings = append(v.Warnings, "no AVX2: inference runs several times slower "+
+					"(a VM needs CPU type \"host\")")
+			}
+		}
 		for _, w := range n.Weights {
 			v.Models = append(v.Models, w.Path)
 		}

internal/control/agentsvc/convert.go

@@ -23,8 +23,15 @@ func NodeFromRegister(r *llmgwv1.Register) inventory.Node {
 		State:          inventory.Ready,
 		AgentVersion:   r.GetAgentVersion(),
 		EngineVersions: r.GetEngineVersions(),
+		EnginesProbed:  r.GetEnginesProbed(),
 		MemoryTotalMB:  int(r.GetMemoryTotalMb()),
 	}
+	if h := r.GetHost(); h != nil {
+		n.Host = discovery.Host{
+			OSID: h.GetOsId(), OSVersion: h.GetOsVersion(), OSCodename: h.GetOsCodename(),
+			Arch: h.GetArch(), CPUFlags: h.GetCpuFlags(), NVIDIADriver: h.GetNvidiaDriver(),
+		}
+	}
 	for _, w := range r.GetWeights() {
 		n.Weights = append(n.Weights, discovery.LocalWeights{
 			Path: w.GetPath(), SizeBytes: w.GetSizeBytes(), Shared: w.GetShared(),

internal/control/agentsvc/service.go

@@ -49,8 +49,14 @@ type Service struct {
 
 	mu    sync.RWMutex
 	conns map[string]*conn
+
+	// engines is what every node is told to install, set once at start.
+	engines map[string]string
 }
 
+// SetEngines sets the engines every node installs, by name and version.
+func (s *Service) SetEngines(e map[string]string) { s.engines = maps.Clone(e) }
+
 // conn is one agent's open stream.
 type conn struct {
 	nodeID string
@@ -157,6 +163,21 @@ func (s *Service) Connect(
 		return err
 	}
 
+	// What this node should have installed. Sent on every registration, so a
+	// node rebuilt from nothing is told the same as one that has been here a
+	// month, and a changed version reaches every node on its next connect.
+	if s.engines != nil {
+		p := &llmgwv1.Provision{}
+		for _, e := range slices.Sorted(maps.Keys(s.engines)) {
+			p.Engines = append(p.Engines, &llmgwv1.EngineWant{Engine: e, Version: s.engines[e]})
+		}
+		if err := stream.Send(&llmgwv1.ControlMessage{
+			Msg: &llmgwv1.ControlMessage_Provision{Provision: p},
+		}); err != nil {
+			return err
+		}
+	}
+
 	// Recover replica state from what this node is already running, before any
 	// reconciliation pass can conclude the cluster is empty and place
 	// duplicates (plan §6.5).
@@ -272,7 +293,8 @@ func (s *Service) applyHeartbeat(nodeID string, hb *llmgwv1.Heartbeat) {
 	storage := hb.GetStorage()
 	memMB := int(hb.GetMemoryTotalMb())
 	if len(used) == 0 && len(problems) == 0 && len(storage) == 0 &&
-		!hb.GetWeightsChanged() && memMB == 0 && !hb.GetEnginesChanged() {
+		!hb.GetWeightsChanged() && memMB == 0 && !hb.GetEnginesChanged() &&
+		!hb.GetProvisionChanged() {
 		return
 	}
 
@@ -339,6 +361,30 @@ func (s *Service) applyHeartbeat(nodeID string, hb *llmgwv1.Heartbeat) {
 		}
 		n.EngineVersions = vers
 	}
+	if hb.GetProvisionChanged() {
+		prev := map[string]inventory.EngineInstall{}
+		for _, p := range n.Provision {
+			prev[p.Engine] = p
+		}
+		n.Provision = n.Provision[:0]
+		for _, p := range hb.GetProvision() {
+			e := inventory.EngineInstall{
+				Engine: p.GetEngine(), Version: p.GetVersion(), Variant: p.GetVariant(),
+				State: p.GetState(), Detail: p.GetDetail(),
+			}
+			// A state change is worth a line; a download's progress is not.
+			if old, ok := prev[e.Engine]; !ok || old.State != e.State {
+				lvl := slog.LevelInfo
+				if e.State == "failed" || e.State == "unsupported" {
+					lvl = slog.LevelWarn
+				}
+				s.log.Log(context.Background(), lvl, "engine installation on a node",
+					"node", nodeID, "engine", e.Engine, "version", e.Version,
+					"variant", e.Variant, "state", e.State, "detail", e.Detail)
+			}
+			n.Provision = append(n.Provision, e)
+		}
+	}
 	s.inv.Upsert(n)
 }
 

internal/control/inventory/inventory.go

@@ -102,6 +102,24 @@ type Node struct {
 	// version decides which metric names and CLI flags apply (plan §14).
 	AgentVersion   string            `json:"agent_version,omitempty"`
 	EngineVersions map[string]string `json:"engine_versions,omitempty"`
+	// EnginesProbed says EngineVersions is an answer, so an empty map means
+	// "has none" rather than "an agent too old to say".
+	EnginesProbed bool `json:"engines_probed,omitempty"`
+
+	// Host is the operating system and processor, as the agent reads them.
+	Host discovery.Host `json:"host"`
+	// Provision is where installing each wanted engine stands on this node.
+	Provision []EngineInstall `json:"provision,omitempty"`
+}
+
+// EngineInstall is where one engine's installation stands on a node.
+type EngineInstall struct {
+	Engine  string `json:"engine"`
+	Version string `json:"version"`
+	Variant string `json:"variant,omitempty"`
+	// State is "installing", "ready", "failed" or "unsupported".
+	State  string `json:"state"`
+	Detail string `json:"detail,omitempty"`
 }
 
 // HasFabric reports whether the node is attached to a fabric.

internal/control/placement/placement.go

@@ -403,9 +403,14 @@ func (s *Scheduler) eligibleNodes(p Profile, fabric string, avoid []string, reje
 		// A node that reports no engines at all is not excluded. That is what
 		// every agent older than this reports, and emptying a fleet on a
 		// control plane upgrade is a worse failure than the one being fixed.
-		if p.Engine != "" && len(n.EngineVersions) > 0 {
+		//
+		// An agent that says it probed is believed when it reports nothing:
+		// that is a node still installing, or one where installing failed,
+		// and either way not a place to start an engine. sim is built into
+		// the agent and never installed.
+		if p.Engine != "" && p.Engine != "sim" && (n.EnginesProbed || len(n.EngineVersions) > 0) {
 			if _, ok := n.EngineVersions[p.Engine]; !ok {
-				reject("does not have " + p.Engine + " installed")
+				reject("does not have " + p.Engine + " installed" + installing(n, p.Engine))
 				continue
 			}
 		}
@@ -526,3 +531,13 @@ func (s *Scheduler) claimedMemory(nodeID string) int {
 	}
 	return total
 }
+
+// installing says why an engine is missing, when the node has said.
+func installing(n inventory.Node, engine string) string {
+	for _, p := range n.Provision {
+		if p.Engine == engine && p.Detail != "" {
+			return " (" + p.State + ": " + p.Detail + ")"
+		}
+	}
+	return ""
+}

internal/control/placement/placement_test.go

@@ -797,3 +797,33 @@ func TestAProfileThatDeclaresNothingClaimsNothing(t *testing.T) {
 		t.Errorf("an undeclared neighbour should not fill the node:\n%s", res.Explain())
 	}
 }
+
+func TestANodeStillInstallingItsEngineIsNotACandidate(t *testing.T) {
+	// A node rebuilt from nothing registers before its agent has installed
+	// anything, and reports no engines. Treated as "too old to say", it was a
+	// candidate for every model at the moment it could run none of them.
+	fresh := node("fresh", "h100-80g", 8)
+	fresh.EnginesProbed = true
+	fresh.Provision = []inventory.EngineInstall{{
+		Engine: "vllm", Version: "0.29.0", State: "installing", Detail: "downloading",
+	}}
+
+	res := New(store(fresh)).Place([]Profile{{
+		Name: "tp1", Engine: "vllm", GPUClass: "h100-80g", GPUsPerNode: 1, Nodes: 1,
+	}}, nil)
+	if res.Placement != nil {
+		t.Fatal("placed on a node whose engine is not installed yet")
+	}
+	if !strings.Contains(res.Explain(), "installing: downloading") {
+		t.Errorf("the rejection should say the engine is on its way:\n%s", res.Explain())
+	}
+
+	// The simulated engine is part of the agent, so it is never installed and
+	// never missing.
+	res = New(store(fresh)).Place([]Profile{{
+		Name: "sim", Engine: "sim", GPUClass: "h100-80g", GPUsPerNode: 1, Nodes: 1,
+	}}, nil)
+	if res.Placement == nil {
+		t.Errorf("sim was refused:\n%s", res.Explain())
+	}
+}

internal/web/templates/dashboard.html

@@ -101,7 +101,7 @@ requested whenever a fallback served it.</p>
 
 <h2>Nodes</h2>
 {{if .Nodes}}
-<table><tr><th>Node</th><th>State</th><th class="num">GPUs</th><th class="num">RAM</th><th class="num">Disk</th><th>Classes</th><th>Fabrics</th><th class="num">Models</th><th class="num">Replicas</th><th>Last seen</th></tr>
+<table><tr><th>Node</th><th>State</th><th class="num">GPUs</th><th class="num">RAM</th><th class="num">Disk</th><th>Engines</th><th>Classes</th><th>Fabrics</th><th class="num">Models</th><th class="num">Replicas</th><th>Last seen</th></tr>
 {{range .Nodes}}<tr>
   <td><code>{{.ID}}</code>{{if .MgmtAddr}} <span class="note">{{.MgmtAddr}}</span>{{end}}</td>
   <td class="state state-{{.State}}">{{.State}}</td>
@@ -111,12 +111,15 @@ requested whenever a fallback served it.</p>
        second, and an em dash where nothing was reported: an agent that
        was never asked about its disk must not read as a full one. */}}
   <td class="num">{{if .DiskTotalGB}}{{.DiskFreeGB}}G/{{.DiskTotalGB}}G{{else}}—{{end}}</td>
+  <td>{{if .Engines}}{{join .Engines}}{{else}}<span class="note">none yet</span>{{end}}</td>
   <td>{{join .Classes}}</td>
   <td>{{join .Fabrics}}</td>
   <td class="num">{{if .Models}}{{len .Models}}{{else}}—{{end}}</td>
   <td class="num">{{.Replicas}}</td>
   <td>{{or .LastSeenAgo "—"}}</td>
-</tr>{{if .Unhealthy}}<tr><td colspan="9" class="note bad">{{join .Unhealthy}}</td></tr>{{end}}
+</tr>{{if .Unhealthy}}<tr><td colspan="11" class="note bad">{{join .Unhealthy}}</td></tr>{{end}}
+{{range .Provision}}{{if ne .State "ready"}}<tr><td colspan="11" class="note{{if or (eq .State "failed") (eq .State "unsupported")}} bad{{end}}">{{.Engine}} {{.Version}}{{if .Variant}} ({{.Variant}}){{end}} {{.State}}: {{.Detail}}</td></tr>{{end}}{{end}}
+{{range .Warnings}}<tr><td colspan="11" class="note bad">{{.}}</td></tr>{{end}}
 {{end}}</table>
 {{else}}<p class="empty">No agents have registered.</p>{{end}}
 

scripts/gitea/release_notes.py

@@ -0,0 +1,103 @@
+#!/usr/bin/env python3
+"""Put each version's CHANGELOG.md section on its Gitea release.
+
+Gitea materialises a release for every pushed tag and leaves its body empty,
+and the release workflow only ever attached binaries — so every release page
+was a list of files with nothing saying what had changed. The changelog is
+where that is written, and it stays the one place it is written: this copies
+it, it does not replace it.
+
+Idempotent: a release whose body already matches is left alone, a version with
+no release is skipped, and nothing is created or deleted.
+
+Usage:
+    GITEA_TOKEN=<token> scripts/gitea/release_notes.py [--tag v0.8.1] [--dry-run]
+
+Without --tag, every version in the changelog is synced. The release workflow
+runs it with the tag it just built; running the workflow by hand runs it for
+all of them, which is how releases made before this existed get their notes.
+"""
+
+import argparse
+import json
+import os
+import re
+import sys
+import urllib.error
+import urllib.parse
+import urllib.request
+
+DEFAULT_INSTANCE = "https://gitea.mynodes.xyz"
+DEFAULT_REPO = "ilker/llmgw"
+
+# "## v0.8.1 — 2026-09-28". The dash is whatever was typed; the version is what
+# matters.
+HEADING = re.compile(r"^## (v\d+\.\d+\.\d+)\b.*$", re.M)
+
+
+def sections(changelog):
+    """Map each version to the text under its heading, up to the next one."""
+    out = {}
+    marks = list(HEADING.finditer(changelog))
+    for i, m in enumerate(marks):
+        end = marks[i + 1].start() if i + 1 < len(marks) else len(changelog)
+        out[m.group(1)] = changelog[m.end():end].strip() + "\n"
+    return out
+
+
+def request(method, url, token, payload=None):
+    data = json.dumps(payload).encode() if payload is not None else None
+    req = urllib.request.Request(url, data=data, method=method)
+    req.add_header("Authorization", f"token {token}")
+    req.add_header("Content-Type", "application/json")
+    try:
+        with urllib.request.urlopen(req, timeout=30) as resp:
+            body = resp.read()
+            return json.loads(body) if body else None
+    except urllib.error.HTTPError as e:
+        if e.code == 404:
+            return None
+        detail = e.read().decode(errors="replace")[:300]
+        raise SystemExit(f"{method} {url} failed: {e.code} {detail}") from e
+
+
+def main():
+    ap = argparse.ArgumentParser(description=__doc__)
+    ap.add_argument("--instance", default=os.environ.get("GITEA_INSTANCE", DEFAULT_INSTANCE))
+    ap.add_argument("--repo", default=os.environ.get("GITEA_REPO", DEFAULT_REPO))
+    ap.add_argument("--changelog", default="CHANGELOG.md")
+    ap.add_argument("--tag", help="sync only this version")
+    ap.add_argument("--dry-run", action="store_true", help="show what would change")
+    args = ap.parse_args()
+
+    token = os.environ.get("GITEA_TOKEN", "")
+    if not token and not args.dry_run:
+        sys.exit("GITEA_TOKEN is not set (use --dry-run to preview)")
+
+    with open(args.changelog, encoding="utf-8") as f:
+        notes = sections(f.read())
+    if args.tag:
+        if args.tag not in notes:
+            # A tag with no section is a release somebody forgot to describe.
+            # Failing says so where it is seen; an empty page says nothing.
+            sys.exit(f"{args.changelog} has no section for {args.tag}")
+        notes = {args.tag: notes[args.tag]}
+
+    base = f"{args.instance.rstrip('/')}/api/v1/repos/{args.repo}/releases"
+    for tag, body in notes.items():
+        if args.dry_run:
+            print(f"would set {tag} ({len(body.splitlines())} lines)")
+            continue
+        rel = request("GET", f"{base}/tags/{urllib.parse.quote(tag)}", token)
+        if rel is None:
+            print(f"skip    {tag}  (no release)")
+            continue
+        if (rel.get("body") or "").strip() == body.strip():
+            print(f"same    {tag}")
+            continue
+        request("PATCH", f"{base}/{rel['id']}", token, {"body": body})
+        print(f"set     {tag}")
+
+
+if __name__ == "__main__":
+    main()