dr: recovered WG-key install + host_loss directive→restore-PLAN (S5 safe halves)

wgtunnel.InstallRecoveredKey: write an escrow-recovered WG private key (create-
only, refuse-overwrite) so the tunnel re-establishes with the same identity/pubkey
(same /32), no keygen. Wired into identity-consume -install-wg-key (opt-in;
pre-S3 blob → logged fresh-keygen fallback). Value never logged.

internal/dr (new): consume the host_loss restore_directive (was logged-ignored)
into an inspectable RestorePlan via the AddConsumer raw seam — per guest
{vmid,archive,target,sizing} + per drive {durable_id→mount} + offsite PBS coord.
DERIVE-AND-SURFACE only; the Consumer has no restore/destroy dependency (execute-
nothing is structural). guest_loss/absent → no plan.

Tests + red-proofs (WG create-only overwrite; plan mode-gate). No secrets on
argv/stdout/logs. The destructive in-place restore is a separate operator-present
STOP-gated drill.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6

internal/dr/plan.go

@@ -0,0 +1,134 @@
+// Package dr consumes the host-loss restore_directive (slice 10D / S5) into an inspectable restore
+// PLAN. It is DERIVE-AND-SURFACE only: the plan is logged (and exposed for the report), never
+// executed — the destructive restore is a separate, operator-present, STOP-gated step. The Consumer
+// has NO restore/destroy API by construction, so "execute nothing" is a structural guarantee.
+package dr
+
+import (
+	"context"
+	"log/slog"
+	"sync"
+
+	"gitea.dooplex.hu/admin/felhom-agent/internal/hub"
+)
+
+// RestorePlan is the derived-but-not-executed host-loss plan: per guest → restore coords + sizing;
+// per drive → durable_id → expected mount. No secrets (coordinates/identifiers/sizes only).
+type RestorePlan struct {
+	Mode   string          `json:"mode"`
+	Guests []PlannedGuest  `json:"guests"`
+	Drives []PlannedDrive  `json:"drives"`
+	PBS    *hub.DRPBSCoord `json:"pbs,omitempty"` // WHERE the offsite backups live (repo/ns/latest snapshot)
+}
+
+// PlannedGuest is one guest to restore in place, from the offsite datastore, at its original sizing.
+type PlannedGuest struct {
+	VMID          int    `json:"vmid"`
+	Archive       string `json:"archive,omitempty"` // explicit archive from the directive; "" → resolve latest at restore time
+	TargetStorage string `json:"target_storage"`    // where the restored volumes land (e.g. local-lvm)
+	Cores         int    `json:"cores"`
+	MemoryBytes   int64  `json:"memory_bytes"`
+	DiskBytes     int64  `json:"disk_bytes"`
+}
+
+// PlannedDrive is one data drive to re-attach BY DURABLE_ID (the wrong-disk guard: a match attaches,
+// a non-match is refused — the matcher, exercised in the Part-4 spike, never resolves to a near disk).
+type PlannedDrive struct {
+	DurableID     string `json:"durable_id"`
+	ExpectedMount string `json:"expected_mount"`
+	Intent        string `json:"intent"`
+}
+
+// BuildRestorePlan derives the plan from a host_loss directive + the live DR recipe. Returns
+// (nil,false) for a guest_loss/absent directive or a nil recipe (nothing to plan). PURE: reads
+// nothing, executes nothing — the whole point of this slice's safe half.
+func BuildRestorePlan(directive *hub.WireRestoreDirective, recipe *hub.DRRecipeHostHalf, restoreStorage string) (*RestorePlan, bool) {
+	if directive == nil || directive.Mode != "host_loss" || recipe == nil {
+		return nil, false
+	}
+	plan := &RestorePlan{Mode: directive.Mode, PBS: recipe.PBS}
+	for _, g := range recipe.Guests {
+		pg := PlannedGuest{
+			VMID:          g.VMID,
+			TargetStorage: restoreStorage,
+			Cores:         g.Cores,
+			MemoryBytes:   g.MemoryBytes,
+			DiskBytes:     g.DiskBytes,
+		}
+		// The directive may name an explicit archive for a specific guest (else the restore step
+		// resolves the latest snapshot from the PBS coord at execution time).
+		if directive.Archive != "" && (directive.VMID == 0 || directive.VMID == g.VMID) {
+			pg.Archive = directive.Archive
+		}
+		plan.Guests = append(plan.Guests, pg)
+	}
+	for _, d := range recipe.Drives {
+		plan.Drives = append(plan.Drives, PlannedDrive{
+			DurableID:     d.DurableID,
+			ExpectedMount: d.MountPath,
+			Intent:        d.Intent,
+		})
+	}
+	return plan, true
+}
+
+// RecipeFunc yields the current DR recipe (the agent-derived scaffolding). It is called ONLY when a
+// host_loss directive is present (a rare DR event), so an on-demand Collect is acceptable.
+type RecipeFunc func(ctx context.Context) *hub.DRRecipeHostHalf
+
+// Consumer implements desired.RawConsumer: on a host_loss restore_directive it builds + SURFACES the
+// plan (structured log + LastPlan for the report/inspection) and executes NOTHING. A guest_loss or
+// absent directive clears the plan. It holds no restore/destroy dependency — surfacing is all it can do.
+type Consumer struct {
+	recipe         RecipeFunc
+	restoreStorage string
+	logger         *slog.Logger
+
+	mu       sync.Mutex
+	lastPlan *RestorePlan
+}
+
+// NewConsumer builds the DR plan consumer. recipe may be nil (then no plan can be built — logged).
+func NewConsumer(recipe RecipeFunc, restoreStorage string, logger *slog.Logger) *Consumer {
+	if logger == nil {
+		logger = slog.Default()
+	}
+	return &Consumer{recipe: recipe, restoreStorage: restoreStorage, logger: logger}
+}
+
+// OnDesiredState implements desired.RawConsumer. Non-host_loss → clear + no-op.
+func (c *Consumer) OnDesiredState(ctx context.Context, resp *hub.DesiredStateResponse) {
+	if resp == nil {
+		return
+	}
+	dir := resp.DesiredState.RestoreDirective
+	if dir == nil || dir.Mode != "host_loss" {
+		c.mu.Lock()
+		c.lastPlan = nil
+		c.mu.Unlock()
+		return
+	}
+	var recipe *hub.DRRecipeHostHalf
+	if c.recipe != nil {
+		recipe = c.recipe(ctx)
+	}
+	plan, ok := BuildRestorePlan(dir, recipe, c.restoreStorage)
+	if !ok {
+		c.logger.Warn("dr: host_loss restore_directive present but no DR recipe available yet — cannot build a plan",
+			"directive_vmid", dir.VMID)
+		return
+	}
+	c.mu.Lock()
+	c.lastPlan = plan
+	c.mu.Unlock()
+	// SURFACE only — the destructive restore is a separate, operator-present step.
+	c.logger.Warn("dr: host_loss RESTORE PLAN derived (NOT executed — supervised in-place restore is a separate, gated step)",
+		"mode", plan.Mode, "guests", len(plan.Guests), "drives", len(plan.Drives), "plan", plan)
+}
+
+// LastPlan returns the most recently derived plan (nil if none / cleared). For the report + tests.
+func (c *Consumer) LastPlan() *RestorePlan {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.lastPlan
+}