feat(cli): orca node key-reset <node> — local known_hosts reset (T02.8, REQ-059)

---ci---
project: orca
phase: 2
milestone: v0.8
status: execute
---/ci---

internal/cli/node.go

@@ -346,6 +346,64 @@ func renderNodeTable(nodes []*model.Node) string {
 	return out
 }
 
+var nodeKeyResetCmd = &cobra.Command{
+	Use:   "key-reset <node>",
+	Short: "Reset the SSH known_hosts entry for a node",
+	Long: `Remove the pinned SSH host key for <node> from the local known_hosts
+file. The next connect re-pins the key via TOFU or --host-key-fingerprint.
+
+LOCAL ONLY (D-046): does not touch the remote host's authorized_keys.
+
+<node> is the node name (for proxmox nodes, this is the host address).`,
+	Args: cobra.ExactArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		nodeArg := args[0]
+
+		registry, closer, err := nodeRegistry()
+		if err != nil {
+			return err
+		}
+		defer closer()
+
+		ctx, cancel := context.WithTimeout(cmd.Context(), 5*time.Second)
+		defer cancel()
+
+		nodes, err := registry.List(ctx)
+		if err != nil {
+			return fmt.Errorf("list nodes: %w", err)
+		}
+		var node *model.Node
+		for _, n := range nodes {
+			if n.Name == nodeArg || n.ID == nodeArg {
+				node = n
+				break
+			}
+		}
+		if node == nil {
+			return fmt.Errorf("node %q not found in the registry", nodeArg)
+		}
+		host := node.Name
+
+		if err := proxmox.ResetHostKey(host); err != nil {
+			return fmt.Errorf("reset host key: %w", err)
+		}
+
+		// Audit-log the reset (REQ-059): actor=cli, action=node.key_reset.
+		db, dbCloser, dbErr := openDB()
+		if dbErr == nil {
+			defer dbCloser()
+			audit := engine.NewAudit(store.NewAuditRepo(db), newLogger())
+			audit.Record(ctx, "cli", "node.key_reset", node.ID, "success", nil, map[string]any{
+				"node": node.Name,
+				"host": host,
+			})
+		}
+
+		fmt.Fprintf(cmd.OutOrStdout(), "✓ Host key reset for %s (next connect will re-pin via TOFU or --host-key-fingerprint)\n", node.Name)
+		return nil
+	},
+}
+
 func init() {
 	nodeJoinCmd.Flags().StringVar(&joinName, "name", "", "node name (required for --type localhost)")
 	nodeJoinCmd.Flags().StringVar(&joinAddr, "addr", "", "node address (default localhost:8443)")
@@ -364,5 +422,6 @@ func init() {
 	nodeCmd.AddCommand(nodeJoinCmd)
 	nodeCmd.AddCommand(nodeLeaveCmd)
 	nodeCmd.AddCommand(nodeListCmd)
+	nodeCmd.AddCommand(nodeKeyResetCmd)
 	rootCmd.AddCommand(nodeCmd)
 }

internal/cli/node_test.go

@@ -13,6 +13,8 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -318,3 +320,120 @@ func padHex(n int) string {
 	}
 	return string(b)
 }
+
+// TestNodeKeyReset removes the target node's known_hosts lines, leaves
+// other hosts' lines intact, and inserts an audit row (T02.8, REQ-059).
+func TestNodeKeyReset(t *testing.T) {
+	_, cleanup := initTestEnv(t)
+	defer cleanup()
+
+	// Seed a proxmox node whose Name is the host address (matches the
+	// key-reset RunE, which uses node.Name as the known_hosts match key).
+	seedProxmoxNode(t, "10.0.0.1", "10.0.0.1:8443")
+
+	// Pre-populate known_hosts: 2 lines for the target + 1 for another host.
+	knownHosts := certpaths.KnownHostsPath()
+	if err := os.MkdirAll(filepath.Dir(knownHosts), 0o755); err != nil {
+		t.Fatalf("mkdir known_hosts dir: %v", err)
+	}
+	original := []byte("[10.0.0.1]:22 ssh-ed25519 AAAAKEY1 host1\n" +
+		"10.0.0.1 ssh-ed25519 AAAAKEY1ALT host1-alt\n" +
+		"[10.0.0.2]:22 ssh-ed25519 AAAAKEY2 host2\n")
+	if err := os.WriteFile(knownHosts, original, 0o600); err != nil {
+		t.Fatalf("write known_hosts: %v", err)
+	}
+
+	resetRootFlags(t)
+	var buf bytes.Buffer
+	rootCmd.SetOut(&buf)
+	rootCmd.SetErr(&buf)
+	rootCmd.SetArgs([]string{"node", "key-reset", "10.0.0.1"})
+	if err := rootCmd.Execute(); err != nil {
+		t.Fatalf("node key-reset: %v", err)
+	}
+	out := buf.String()
+	if !strings.Contains(out, "Host key reset for 10.0.0.1") {
+		t.Errorf("output missing reset confirmation: %s", out)
+	}
+
+	// known_hosts: target's 2 lines removed, other host's line intact.
+	data, err := os.ReadFile(knownHosts)
+	if err != nil {
+		t.Fatalf("read known_hosts: %v", err)
+	}
+	result := string(data)
+	if strings.Contains(result, "AAAAKEY1") {
+		t.Errorf("target key line 1 not removed: %s", result)
+	}
+	if strings.Contains(result, "AAAAKEY1ALT") {
+		t.Errorf("target key line 2 not removed: %s", result)
+	}
+	if !strings.Contains(result, "AAAAKEY2") {
+		t.Errorf("other host's line was removed (should be intact): %s", result)
+	}
+
+	// Audit row inserted with action=node.key_reset.
+	db, err := store.Open(certpaths.DBPath())
+	if err != nil {
+		t.Fatalf("open db: %v", err)
+	}
+	defer db.Close()
+	entries, err := store.NewAuditRepo(db).List(context.Background(), 50)
+	if err != nil {
+		t.Fatalf("list audit: %v", err)
+	}
+	found := false
+	for _, e := range entries {
+		if e.Action == "node.key_reset" && strings.Contains(e.Resource, "10.0.0.1") {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Errorf("audit row for node.key_reset not inserted: %+v", entries)
+	}
+}
+
+// TestNodeKeyReset_NodeNotFound verifies key-reset errors when the
+// node is not in the registry (T02.8).
+func TestNodeKeyReset_NodeNotFound(t *testing.T) {
+	_, cleanup := initTestEnv(t)
+	defer cleanup()
+	resetRootFlags(t)
+	var buf bytes.Buffer
+	rootCmd.SetOut(&buf)
+	rootCmd.SetErr(&buf)
+	rootCmd.SetArgs([]string{"node", "key-reset", "no.such.host"})
+	err := rootCmd.Execute()
+	if err == nil {
+		t.Fatal("expected error for unknown node, got nil")
+	}
+	if !strings.Contains(err.Error(), "not found") {
+		t.Errorf("error should mention not found, got: %v", err)
+	}
+}
+
+func seedProxmoxNode(t *testing.T, name, addr string) string {
+	t.Helper()
+	db, err := store.Open(certpaths.DBPath())
+	if err != nil {
+		t.Fatalf("open db: %v", err)
+	}
+	defer db.Close()
+	repo := store.NewNodeRepo(db)
+	ctx := context.Background()
+	n := &model.Node{
+		ID:       "node-" + name,
+		Name:     name,
+		Address:  addr,
+		State:    model.NodeStateReady,
+		JoinedAt: time.Now().UTC(),
+		LastSeen: time.Now().UTC(),
+		Kind:     string(model.NodeKindProxmox),
+		OS:       "pve",
+	}
+	if err := repo.Insert(ctx, n); err != nil {
+		t.Fatalf("insert proxmox node: %v", err)
+	}
+	return n.ID
+}

internal/proxmox/bootstrap.go

@@ -462,3 +462,59 @@ func validateSudoers() error {
 	}
 	return nil
 }
+
+// ResetHostKey removes all known_hosts entries for the given host from
+// certpaths.KnownHostsPath() (REQ-059, D-046, AD-029). It rewrites the
+// file atomically via security.WriteAtomic. LOCAL ONLY — it does NOT
+// touch the remote host's authorized_keys (D-046). The next connect
+// re-pins the host key via TOFU (T02.6) or the --host-key-fingerprint
+// pinned path (T02.5).
+//
+// A line matches when its first whitespace-delimited field (the host
+// pattern, normalized via knownhosts.Normalize) equals the normalized
+// target host. Comment/blank lines are preserved.
+func ResetHostKey(host string) error {
+	if host == "" {
+		return fmt.Errorf("ResetHostKey: host is required")
+	}
+	path := certpaths.KnownHostsPath()
+	existing, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil // nothing to reset
+		}
+		return fmt.Errorf("ResetHostKey: read known_hosts: %w", err)
+	}
+	target := knownhosts.Normalize(host)
+	var kept []byte
+	removed := 0
+	for _, line := range strings.Split(string(existing), "\n") {
+		trimmed := strings.TrimSpace(line)
+		if trimmed == "" || strings.HasPrefix(trimmed, "#") {
+			kept = append(kept, []byte(line+"\n")...)
+			continue
+		}
+		fields := strings.Fields(trimmed)
+		if len(fields) == 0 {
+			kept = append(kept, []byte(line+"\n")...)
+			continue
+		}
+		if knownhosts.Normalize(fields[0]) == target {
+			removed++
+			continue
+		}
+		kept = append(kept, []byte(line+"\n")...)
+	}
+	if removed == 0 {
+		return nil
+	}
+	// Ensure the kept buffer ends with exactly one trailing newline.
+	kept = bytes.TrimRight(kept, "\n")
+	if len(kept) > 0 {
+		kept = append(kept, '\n')
+	}
+	if err := security.WriteAtomic(path, 0o600, kept); err != nil {
+		return fmt.Errorf("ResetHostKey: rewrite known_hosts: %w", err)
+	}
+	return nil
+}

internal/proxmox/bootstrap_test.go

@@ -711,3 +711,76 @@ func TestBootstrapProxmox_PopulatesHostKeyFingerprint(t *testing.T) {
 		t.Errorf("Result.HostKeyFingerprint = %q, want SHA256: prefix", result.HostKeyFingerprint)
 	}
 }
+
+// TestResetHostKey_RemovesTargetLines verifies that ResetHostKey
+// removes all known_hosts lines for the target host while leaving
+// other hosts' lines intact (T02.8, REQ-059, D-046).
+func TestResetHostKey_RemovesTargetLines(t *testing.T) {
+	home := setupORCAHome(t)
+	path := filepath.Join(home, "known_hosts")
+	original := []byte("[10.0.0.1]:22 ssh-ed25519 AAAAKEY1 host1\n" +
+		"10.0.0.1 ssh-ed25519 AAAAKEY1ALT host1-alt\n" +
+		"[10.0.0.2]:22 ssh-ed25519 AAAAKEY2 host2\n")
+	if err := os.WriteFile(path, original, 0o600); err != nil {
+		t.Fatalf("write known_hosts: %v", err)
+	}
+
+	if err := ResetHostKey("10.0.0.1"); err != nil {
+		t.Fatalf("ResetHostKey: %v", err)
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read known_hosts: %v", err)
+	}
+	result := string(data)
+	if strings.Contains(result, "AAAAKEY1") {
+		t.Errorf("target host key line not removed: %s", result)
+	}
+	if strings.Contains(result, "AAAAKEY1ALT") {
+		t.Errorf("target host alt key line not removed: %s", result)
+	}
+	if !strings.Contains(result, "AAAAKEY2") {
+		t.Errorf("other host's line was removed (should be intact): %s", result)
+	}
+}
+
+// TestResetHostKey_NoMatchingLinesIsNoop verifies that ResetHostKey is
+// a no-op when no lines match (T02.8).
+func TestResetHostKey_NoMatchingLinesIsNoop(t *testing.T) {
+	home := setupORCAHome(t)
+	path := filepath.Join(home, "known_hosts")
+	original := []byte("[10.0.0.2]:22 ssh-ed25519 AAAAKEY2 host2\n")
+	if err := os.WriteFile(path, original, 0o600); err != nil {
+		t.Fatalf("write known_hosts: %v", err)
+	}
+
+	if err := ResetHostKey("10.0.0.99"); err != nil {
+		t.Fatalf("ResetHostKey: %v", err)
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read known_hosts: %v", err)
+	}
+	if string(data) != string(original) {
+		t.Errorf("known_hosts changed on no-match: got %q, want %q", data, original)
+	}
+}
+
+// TestResetHostKey_MissingFileIsNoop verifies ResetHostKey returns nil
+// when known_hosts does not exist (T02.8).
+func TestResetHostKey_MissingFileIsNoop(t *testing.T) {
+	setupORCAHome(t)
+	if err := ResetHostKey("10.0.0.1"); err != nil {
+		t.Errorf("ResetHostKey on missing file should be no-op, got: %v", err)
+	}
+}
+
+// TestResetHostKey_EmptyHostErrors verifies ResetHostKey rejects an
+// empty host (T02.8).
+func TestResetHostKey_EmptyHostErrors(t *testing.T) {
+	if err := ResetHostKey(""); err == nil {
+		t.Error("expected error for empty host, got nil")
+	}
+}