fix(A): bootstrap plumbing — init creates SSH key + known_hosts + master key (REQ-164)

Fixes UAT issues 1, 8, 9, 12C, 13:
- orca init: generates SSH keypair (GenerateOrLoadSSHKey), creates
  empty known_hosts (0600), generates master key (GenerateMasterKey +
  SaveMasterKey). All were missing from runInit — every downstream
  SSH/secrets/cluster operation failed on a fresh init.
- TOFUHostKeyCallbackPath: creates known_hosts file if it doesn't exist
  (defense-in-depth alongside init)
- Linux bootstrap: replaces buggy inline TOFU with
  proxmox.TOFUHostKeyCallbackPath (first-connect key capture works)
- --type flag help: includes "linux" (was "localhost or proxmox")
- doctor network: SSH exec probe (was HTTP /healthz to :8443 — no
  daemon in SSH-push model R-001)

---ci---
project: orca
milestone: v0.12.18
phase: A
status: complete
requirements:
  covered: [164]
---/ci---

internal/cli/init.go

@@ -6,9 +6,12 @@ import (
 	"encoding/pem"
 	"fmt"
 	"os"
+	"path/filepath"
 	"time"
 
 	"github.com/google/uuid"
+
+	"golang.org/x/crypto/ssh"
 	"github.com/spf13/cobra"
 
 	"git.cloudinit.dev/coreci/orca/internal/acl"
@@ -16,6 +19,7 @@ import (
 	"git.cloudinit.dev/coreci/orca/internal/identity"
 	"git.cloudinit.dev/coreci/orca/internal/model"
 	"git.cloudinit.dev/coreci/orca/internal/paths"
+	"git.cloudinit.dev/coreci/orca/internal/secrets"
 	"git.cloudinit.dev/coreci/orca/internal/security"
 	"git.cloudinit.dev/coreci/orca/internal/store"
 )
@@ -59,7 +63,8 @@ func runInit(out interface{ Write([]byte) (int, error) }) error {
 		Database        string       `json:"database"`
 		CAFingerprint   string       `json:"ca_fingerprint,omitempty"`
 		CertFingerprint string       `json:"cert_fingerprint,omitempty"`
-		OS              string       `json:"os"`
+		OS              string       `json:"os"
+	"path/filepath"`
 		NodeID          string       `json:"node_id"`
 		NodeName        string       `json:"node_name"`
 		Steps           []stepResult `json:"steps"`
@@ -138,6 +143,71 @@ func runInit(out interface{ Write([]byte) (int, error) }) error {
 		}
 	}
 
+	// Step 4a: SSH keypair (idempotent — GenerateOrLoadSSHKey has a fast-path).
+	// REQ-164: without this, every sshpush.Transport dial fails because
+	// the orca SSH key doesn't exist after a fresh init.
+	sshKeyPEM, sshPubLine, err := security.GenerateOrLoadSSHKey(dir)
+	if err != nil {
+		return fmt.Errorf("generate SSH keypair: %w", err)
+	}
+	_ = sshKeyPEM
+	sshKeyFp := ""
+	if pubKey, err := ssh.ParsePublicKey(sshPubLine); err == nil {
+		sshKeyFp = ssh.FingerprintSHA256(pubKey)
+	}
+	summary.Steps = append(summary.Steps, stepResult{Label: "ssh-key", Status: "ok", Detail: sshKeyFp[:min(16, len(sshKeyFp))] + "..."})
+	if !jsonOutput {
+		fmt.Fprintf(out, "\xe2\x9c\x93 SSH keypair provisioned: fp=%s\n", sshKeyFp[:min(16, len(sshKeyFp))]+"...")
+	}
+
+	// Step 4b: known_hosts file (empty, 0600). Without this, the TOFU
+	// host-key callback fails with "no such file" on the first SSH dial
+	// (knownhosts.New requires the file to exist).
+	knownHostsPath := certpaths.KnownHostsPath()
+	if _, err := os.Stat(knownHostsPath); err != nil {
+		if os.IsNotExist(err) {
+			if err := os.WriteFile(knownHostsPath, []byte{}, 0o600); err != nil {
+				return fmt.Errorf("create known_hosts: %w", err)
+			}
+		} else {
+			return fmt.Errorf("stat known_hosts: %w", err)
+		}
+	}
+	summary.Steps = append(summary.Steps, stepResult{Label: "known-hosts", Status: "ok", Detail: knownHostsPath})
+	if !jsonOutput {
+		fmt.Fprintf(out, "\xe2\x9c\x93 Known hosts file created: %s\n", knownHostsPath)
+	}
+
+	// Step 4c: master key (32-byte random, 0600). Without this, secrets
+	// set/get/rotate and cluster seal/unseal all fail with "stat master
+	// key: no such file or directory" on a fresh init.
+	masterKeyPath := paths.MasterKeyPath()
+	if _, err := os.Stat(masterKeyPath); err != nil {
+		if os.IsNotExist(err) {
+			os.MkdirAll(filepath.Dir(masterKeyPath), 0o755)
+			masterKey, err := secrets.GenerateMasterKey()
+			if err != nil {
+				return fmt.Errorf("generate master key: %w", err)
+			}
+			if err := secrets.SaveMasterKey(masterKeyPath, masterKey); err != nil {
+				return fmt.Errorf("save master key: %w", err)
+			}
+			// Zero the key from memory (defense-in-depth, REQ-154).
+			defer secrets.ZeroKey(masterKey)
+			summary.Steps = append(summary.Steps, stepResult{Label: "master-key", Status: "ok", Detail: "generated"})
+			if !jsonOutput {
+				fmt.Fprintf(out, "\xe2\x9c\x93 Master key generated: %s\n", masterKeyPath)
+			}
+		} else {
+			return fmt.Errorf("stat master key: %w", err)
+		}
+	} else {
+		summary.Steps = append(summary.Steps, stepResult{Label: "master-key", Status: "skipped", Detail: "already present"})
+		if !jsonOutput {
+			fmt.Fprintf(out, "\xe2\x9c\x93 Master key: already present\n")
+		}
+	}
+
 	// Step 5: OS detection.
 	osDetected := detectOS()
 	summary.OS = osDetected

internal/cli/node.go

@@ -503,7 +503,7 @@ func init() {
 	nodeJoinCmd.Flags().StringVar(&joinName, "name", "", "node name (required for --type localhost)")
 	nodeJoinCmd.Flags().StringVar(&joinAddr, "addr", "", "node address (default localhost:8443)")
 	nodeJoinCmd.Flags().StringVar(&joinCAFinger, "ca-fingerprint", "", "pin CA cert SHA-256 (REQ-026); fails if on-disk CA doesn't match")
-	nodeJoinCmd.Flags().StringVar(&joinType, "type", "localhost", "node type: localhost (default) or proxmox (SSH bootstrap)")
+	nodeJoinCmd.Flags().StringVar(&joinType, "type", "localhost", "node type: localhost (default), proxmox, or linux (SSH bootstrap)")
 	nodeJoinCmd.Flags().StringVar(&joinHost, "host", "", "proxmox host address (IP/hostname, no port; required for --type proxmox)")
 	nodeJoinCmd.Flags().StringVar(&joinSSHUser, "ssh-user", "root", "SSH username for proxmox bootstrap (default root)")
 	nodeJoinCmd.Flags().StringVar(&joinSSHKey, "ssh-key", "", "SSH private key path for proxmox bootstrap (R-021: no passwords; default: orca key)")

internal/doctor/doctor.go

@@ -32,6 +32,7 @@ import (
 	"git.cloudinit.dev/coreci/orca/internal/osdetect"
 	"git.cloudinit.dev/coreci/orca/internal/proxmox"
 	"git.cloudinit.dev/coreci/orca/internal/security"
+	"git.cloudinit.dev/coreci/orca/internal/sshpush"
 	"git.cloudinit.dev/coreci/orca/internal/store"
 	"git.cloudinit.dev/coreci/orca/internal/transport"
 )
@@ -225,22 +226,22 @@ func DB() Check {
 	}
 }
 
-// Network probes peer reachability via mTLS /healthz (REQ-032 completion).
-// Peers are sourced from the persisted nodes table (not the in-memory
-// PeerRegistry, which is empty at CLI time). Zero peers → WARN (single-node
-// is legitimate). Any peer unreachable → FAIL (D-038).
+// Network probes peer reachability via SSH exec (REQ-164 Phase A5).
+// The SSH-push model (R-001) has no daemon on :8443, so the HTTP /healthz
+// probe is replaced with an SSH "echo ok" exec. Peers are sourced from
+// the persisted nodes table. Zero peers → WARN (single-node is
+// legitimate). Any peer unreachable → FAIL (D-038).
 func Network() Check {
 	return Check{
 		Name:        "network",
-		Description: "peer reachability via mTLS /healthz probe",
+		Description: "peer reachability via SSH exec probe",
 		Run: func(ctx context.Context) (Result, string) {
-			caPath := certpaths.CACertPath()
-			certPath := certpaths.ServerCertPath()
-			keyPath := certpaths.ServerKeyPath()
+			keyPath := certpaths.SSHKeyPath()
+			khPath := certpaths.KnownHostsPath()
 
-			// Check that cert files exist before attempting probes.
-			if _, err := os.Stat(caPath); err != nil {
-				return ResultFail, fmt.Sprintf("CA cert missing: %v (run `orca cert init`)", err)
+			// Check that the SSH key exists.
+			if _, err := os.Stat(keyPath); err != nil {
+				return ResultFail, fmt.Sprintf("SSH key missing: %v (run `orca init`)", err)
 			}
 
 			path := certpaths.DBPath()
@@ -266,15 +267,23 @@ func Network() Check {
 				return ResultWarn, "no peers registered (single-node?)"
 			}
 
+			// For localhost nodes, check SSH to 127.0.0.1:22 (may fail if
+			// SSH isn't running — that's OK, report WARN not FAIL).
+			transport := sshpush.NewTransport(keyPath, khPath)
+
 			var lines []string
 			anyFail := false
 			for _, n := range live {
-				probeCtx, cancel := context.WithTimeout(ctx, 3*time.Second)
-				err := probeHealthz(probeCtx, caPath, certPath, keyPath, n.Name, n.Address)
+				probeCtx, cancel := context.WithTimeout(ctx, 5*time.Second)
+				_, err := transport.Exec(probeCtx, n.Name, "echo ok")
 				cancel()
 				if err != nil {
-					anyFail = true
-					lines = append(lines, fmt.Sprintf("  ✗ %s (%s): %v", n.Name, n.Address, err))
+					if n.Kind == string(model.NodeKindLocalhost) {
+						lines = append(lines, fmt.Sprintf("  ⚠ %s (%s): %v (SSH to self may not be running)", n.Name, n.Address, err))
+					} else {
+						anyFail = true
+						lines = append(lines, fmt.Sprintf("  ✗ %s (%s): %v", n.Name, n.Address, err))
+					}
 				} else {
 					lines = append(lines, fmt.Sprintf("  ✓ %s (%s)", n.Name, n.Address))
 				}

internal/doctor/doctor_test.go

@@ -99,6 +99,10 @@ func TestRunWithCAAndServerCert(t *testing.T) {
 	if err := security.WriteKey(dir+"/server.key", keyPEM); err != nil {
 		t.Fatalf("WriteKey: %v", err)
 	}
+	// REQ-164: network check requires the SSH key to exist.
+	if _, _, err := security.GenerateOrLoadSSHKey(dir); err != nil {
+		t.Fatalf("GenerateOrLoadSSHKey: %v", err)
+	}
 
 	rep := Run(context.Background())
 	byName := make(map[string]CheckResult, len(rep.Checks))
@@ -152,6 +156,9 @@ func TestDBCheck_IntegrityOK(t *testing.T) {
 func TestNetworkCheck_NoPeers(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("ORCA_HOME", dir)
+
+	// REQ-164: network check requires SSH key.
+	_, _, _ = security.GenerateOrLoadSSHKey(dir)
 	t.Setenv("ORCA_DB", filepath.Join(dir, "orca.db"))
 
 	// Create a CA + server cert so the network check can build a client.
@@ -179,6 +186,9 @@ func TestNetworkCheck_NoPeers(t *testing.T) {
 func TestNetworkCheck_PeerUnreachable(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("ORCA_HOME", dir)
+
+	// REQ-164: network check requires SSH key.
+	_, _, _ = security.GenerateOrLoadSSHKey(dir)
 	t.Setenv("ORCA_DB", filepath.Join(dir, "orca.db"))
 
 	// Create a CA + server cert.
@@ -225,8 +235,8 @@ func TestNetworkCheck_NoCert(t *testing.T) {
 	if r != ResultFail {
 		t.Errorf("Network check: got %s, want FAIL — %s", r, msg)
 	}
-	if !strings.Contains(msg, "CA cert missing") {
-		t.Errorf("Network check message should mention missing CA, got: %s", msg)
+	if !strings.Contains(msg, "SSH key missing") && !strings.Contains(msg, "CA cert missing") {
+		t.Errorf("Network check message should mention missing key/cert, got: %s", msg)
 	}
 }
 

internal/linux/bootstrap.go

@@ -30,9 +30,9 @@ import (
 	"time"
 
 	"golang.org/x/crypto/ssh"
-	"golang.org/x/crypto/ssh/knownhosts"
 
 	"git.cloudinit.dev/coreci/orca/internal/certpaths"
+	"git.cloudinit.dev/coreci/orca/internal/proxmox"
 	"git.cloudinit.dev/coreci/orca/internal/security"
 )
 
@@ -112,17 +112,16 @@ func BootstrapLinux(ctx context.Context, opts Options) (*Result, error) {
 		}
 		hostKeyCallback = hkcb
 	} else {
-		hkcb, err := knownhosts.New(certpaths.KnownHostsPath())
+		// REQ-164 / Phase A3: reuse the tested Proxmox TOFU callback
+		// which handles first-connect key capture + known_hosts file
+		// creation (create-on-open). The previous inline implementation
+		// failed on first connect with a raw KeyError because it never
+		// wrote the captured key.
+		hkcb, err := proxmox.TOFUHostKeyCallbackPath(certpaths.KnownHostsPath(), sshAddr, &capturedHostKey)
 		if err != nil {
 			return nil, fmt.Errorf("linux bootstrap: known_hosts: %w", err)
 		}
-		hostKeyCallback = ssh.HostKeyCallback(func(hostname string, remote net.Addr, key ssh.PublicKey) error {
-			err := hkcb(hostname, remote, key)
-			if err == nil {
-				capturedHostKey = key
-			}
-			return err
-		})
+		hostKeyCallback = hkcb
 	}
 
 	sshConfig := &ssh.ClientConfig{

internal/proxmox/bootstrap.go

@@ -318,6 +318,18 @@ func TOFUHostKeyCallbackPath(knownHostsPath, addr string, capturedKey *ssh.Publi
 	if knownHostsPath == "" {
 		knownHostsPath = certpaths.KnownHostsPath()
 	}
+	// REQ-164 / Phase A2: create the known_hosts file if it doesn't
+	// exist (knownhosts.New requires the file to be present). This is
+	// defense-in-depth alongside init.go which also creates it.
+	if _, err := os.Stat(knownHostsPath); err != nil {
+		if os.IsNotExist(err) {
+			if writeErr := security.WriteAtomic(knownHostsPath, 0o600, []byte{}); writeErr != nil {
+				return nil, fmt.Errorf("tofu create known_hosts: %w", writeErr)
+			}
+		} else {
+			return nil, fmt.Errorf("tofu stat known_hosts: %w", err)
+		}
+	}
 	cb, err := knownhosts.New(knownHostsPath)
 	if err != nil {
 		return nil, err