diff --git a/cmd/mavend/actions_act.go b/cmd/mavend/actions_act.go
index 2b96855..f3395dc 100644
--- a/cmd/mavend/actions_act.go
+++ b/cmd/mavend/actions_act.go
@@ -51,6 +51,12 @@ func (h *reactiveHandler) actionAct(ctx context.Context, dec router.Decision) st
 			phrase := actPhrase(dec.Slots.Fn, dec.Slots.Args)
 			h.park(dec.Slots.Fn, dec.Slots.Args, phrase)
 			return "выполнить «" + phrase + "»? скажи «да» или «нет»."
+		case errors.Is(err, tool.ErrNeedsAuthedSurface):
+			// Irreversible (internal/tool/risk.go). A confirm turn would not
+			// help: everything that proposed this act — the STT, the router,
+			// the fuzzy allowlist match — is a guess, and a spoken "да" checks
+			// none of it. She names the gap instead.
+			return "это я из голоса не выполню — после него ничего не вернуть. запусти сам, если правда надо."
 		case errors.Is(err, tool.ErrNotEnabled):
 			return h.proposeGap(ctx, dec)
 		case errors.Is(err, tool.ErrNotConnected), errors.Is(err, mcp.ErrNotConnected), errors.Is(err, mcp.ErrNoServer):
diff --git a/docs/design.md b/docs/design.md
index 4d204ab..f29a2ad 100644
--- a/docs/design.md
+++ b/docs/design.md
@@ -293,6 +293,40 @@ don't improvise.** Destructive ones still gate behind confirm.
 Misroute correction is append-only and grows the router's examples with use —
 same shape as `nudges.outcome` tuning cooldowns, no retrain.
 
+#### Risk tiers, not one boolean
+
+`Destructive` on a tool row is one bit set by whoever ticked the checkbox on
+`/tools`. It is a mechanism, and it never said which acts are destructive,
+whether a confirmed act stays confirmed, or what a new tool domain inherits.
+`internal/tool/risk.go` is the policy (Vikunja #449). The tier is DERIVED from
+the row, not stored, so it can be argued with in one place instead of being
+whatever the last person to enable the tool believed.
+
+| Tier | What it is | What it costs |
+|---|---|---|
+| `safe` | a read, or a change he can undo by saying the opposite | runs on first hearing |
+| `destructive` | it changes something real and undoing it takes work | one confirm turn, every time |
+| `irreversible` | the thing does not come back: a wipe, a format, a delete with no bin | voice may not authorise it at all |
+
+Three rules fall out, and they are the part that was missing:
+
+- **Which acts are destructive is not only the checkbox.** A house row always
+  is, because there is no read-only way to turn the heating off. A row whose
+  argv names one of the irreversible verbs always is, whatever the row says.
+- **A confirmed act never stays confirmed.** At any tier. A confirmation binds
+  one capability, one target and one argument list, and it dies with the parked
+  turn (90s). "The same act again" is a new act. A sticky confirm is a standing
+  grant and nothing on the voice path may hold one.
+- **A new domain inherits `destructive`, not `safe`.** A dispatch shape the
+  policy does not recognise gets the confirm turn. A domain argues its way down
+  to running freely; it never has to argue its way up to being gated.
+
+The irreversible tier is refused rather than asked about, because a confirm
+turn would be theatre: everything that proposed the act — an STT guess, a
+router guess, a fuzzy allowlist match — is a guess, and a spoken "да" checks
+none of it. She names the gap and he runs it himself. The row stays enabled;
+refusing to run it from voice is not the same as taking it off the allowlist.
+
 ---
 
 ## Voice pipeline (STT / TTS)
diff --git a/internal/tool/risk.go b/internal/tool/risk.go
new file mode 100644
index 0000000..cb1ad38
--- /dev/null
+++ b/internal/tool/risk.go
@@ -0,0 +1,145 @@
+package tool
+
+import (
+	"strings"
+
+	"github.com/kami/maven/internal/ipc"
+	"github.com/kami/maven/internal/mcp"
+	"github.com/kami/maven/internal/smarthome"
+)
+
+// Risk tiers (Vikunja #449).
+//
+// What existed before this file was a mechanism and no policy: one
+// `Destructive` boolean per row, set by whoever ticked the checkbox on /tools.
+// Nothing said which acts are destructive, whether a confirmed act stays
+// confirmed, or what a new tool domain inherits — so every domain answered
+// those questions for itself, and two of them answered differently.
+//
+// The tiers below are the policy. They are derived from the row, not stored:
+// a derivation can be argued with and corrected in one place, while a column
+// is whatever the last person to enable the tool believed.
+//
+// The three questions, answered once:
+//
+//   - WHICH ACTS ARE DESTRUCTIVE. A house row always is, because there is no
+//     read-only way to turn the heating off. A row whose argv names one of the
+//     irreversible verbs always is, whatever the checkbox says. Everything else
+//     is what the row was enabled as.
+//   - DOES A CONFIRMED ACT STAY CONFIRMED. No. Never, at any tier. A
+//     confirmation binds one capability, one target and one argument list, and
+//     it expires with the parked turn (confirmTTL, 90s). "Same act again" is a
+//     new act and costs a new turn. A sticky confirm is a standing grant, and
+//     nothing on the voice path may hold one.
+//   - WHAT A NEW DOMAIN INHERITS. The default is TierDestructive, not
+//     TierSafe. A dispatch shape this file does not recognise gets the confirm
+//     turn — a new domain must argue its way DOWN to running freely, never up
+//     to needing a confirm.
+type Risk string
+
+const (
+	// TierSafe — a read, or a mutation the owner can undo by saying the
+	// opposite. Runs on first hearing.
+	TierSafe Risk = "safe"
+	// TierDestructive — it changes something real and undoing it takes work.
+	// One confirm turn, every time, never remembered.
+	TierDestructive Risk = "destructive"
+	// TierIrreversible — the thing it acts on does not come back: a wipe, a
+	// format, a delete with no bin behind it. A confirm turn is not enough,
+	// because the whole chain that proposed it — an STT guess, a router guess,
+	// a fuzzy allowlist match — has a spoken "да" as its only check. She names
+	// the gap and he runs it himself.
+	TierIrreversible Risk = "irreversible"
+)
+
+// Policy — what a tier requires of the act path.
+//
+// There is deliberately no "sticky for" field. Non-stickiness is the policy,
+// and a knob that could turn it off would be the thing to argue with instead
+// of the rule.
+type Policy struct {
+	// Confirm — the act does not run on first hearing.
+	Confirm bool
+	// VoiceMayRun — a spoken confirmation is enough authority to run it.
+	VoiceMayRun bool
+}
+
+// PolicyFor returns the requirements of a tier. An unknown tier is treated as
+// destructive, for the same reason the default derivation is.
+func PolicyFor(r Risk) Policy {
+	switch r {
+	case TierSafe:
+		return Policy{Confirm: false, VoiceMayRun: true}
+	case TierIrreversible:
+		return Policy{Confirm: true, VoiceMayRun: false}
+	default:
+		return Policy{Confirm: true, VoiceMayRun: true}
+	}
+}
+
+// irreversibleVerbs — argv heads and subcommands that destroy the thing they
+// name. Matched as whole argv elements, never as substrings: "rm" must not
+// fire on "/usr/bin/rmdir-report" and "drop" must not fire on "dropbox".
+//
+// The list is short on purpose. It is not a sandbox and it does not try to be
+// one — an enabled row can already run anything the daemon's user can run.
+// What it is, is the set of words that mean "and then it is gone", so that the
+// one act nobody can walk back is the one act a spoken "да" cannot authorise.
+var irreversibleVerbs = map[string]bool{
+	"rm": true, "rmdir": true, "shred": true, "srm": true,
+	"mkfs": true, "fdisk": true, "parted": true, "wipefs": true,
+	"dd": true, "format": true,
+	"drop": true, "drop-database": true, "destroy": true, "purge": true,
+	"prune": true, "truncate": true,
+}
+
+// RiskOf derives the tier of an enabled tool row.
+func RiskOf(t ipc.Tool) Risk {
+	if isIrreversible(t.Cmd) {
+		return TierIrreversible
+	}
+	// A house row is a physical change to the flat, and the confirm turn on it
+	// is structural rather than a column: /tools writes the checkbox straight
+	// through on enable, so unticking it once turned an unlock into a row that
+	// ran on first hearing. Nothing any surface writes removes the second turn
+	// from a physical device.
+	if _, _, ok := smarthome.ParseCmd(t.Cmd); ok {
+		return TierDestructive
+	}
+	// An MCP row is a call to somebody else's server. It is enabled with a
+	// fingerprint of what it declared at approval time (Vikunja #251), and the
+	// tier tracks the same flag every other row uses — the point of this branch
+	// is that it is NOT special-cased into running freely.
+	if _, _, ok := mcp.ParseCmd(t.Cmd); ok {
+		if t.Destructive {
+			return TierDestructive
+		}
+		return TierSafe
+	}
+	if t.Destructive {
+		return TierDestructive
+	}
+	if len(t.Cmd) == 0 {
+		// Not a shape this file knows how to read. The default is the confirm
+		// turn: a new domain argues its way down, not up.
+		return TierDestructive
+	}
+	return TierSafe
+}
+
+// isIrreversible reports whether any argv element is one of the verbs that
+// destroys what it names. Every element, not just the head: "sudo rm" and
+// "docker volume prune" both hide the verb behind a wrapper.
+func isIrreversible(cmd []string) bool {
+	for _, arg := range cmd {
+		word := strings.ToLower(strings.TrimSpace(arg))
+		// Take the last path element, so /bin/rm reads as rm.
+		if i := strings.LastIndex(word, "/"); i >= 0 {
+			word = word[i+1:]
+		}
+		if irreversibleVerbs[word] {
+			return true
+		}
+	}
+	return false
+}
diff --git a/internal/tool/tool.go b/internal/tool/tool.go
index d948d58..6b27924 100644
--- a/internal/tool/tool.go
+++ b/internal/tool/tool.go
@@ -67,6 +67,12 @@ var (
 	// proposal, and drafting a new proposal for a tool that already exists and
 	// is enabled is a lie about what is wrong.
 	ErrNotConnected = errors.New("tool is enabled but its backend is not connected")
+	// ErrNeedsAuthedSurface — the row is enabled and the act is understood,
+	// and its tier is one a spoken "да" may not authorise (risk.go,
+	// TierIrreversible). Held apart from ErrNeedsConfirm because there is no
+	// confirm turn that would help: asking again would imply the second answer
+	// changes the outcome.
+	ErrNeedsAuthedSurface = errors.New("tool is irreversible and voice may not authorise it")
 )
 
 // MCPCaller is the seam for an act that is an MCP tool call rather than a
@@ -121,7 +127,12 @@ func (e *Executor) WithHome(h HomeCaller) *Executor {
 // Exec looks up name in the store and runs Cmd+args as argv (no shell).
 // confirmed=true is the second turn of a destructive act (the user said "да");
 // it bypasses the ErrNeedsConfirm gate. Non-enabled ⇒ ErrNotEnabled; a
-// destructive tool with confirmed=false ⇒ ErrNeedsConfirm.
+// destructive tool with confirmed=false ⇒ ErrNeedsConfirm; an irreversible one
+// ⇒ ErrNeedsAuthedSurface, confirmed or not.
+//
+// Exec IS the voice path. Nothing else calls it, which is why the tier check
+// needs no surface argument: the authority it can offer a tool is a spoken
+// "да", and TierIrreversible says that is not enough.
 func (e *Executor) Exec(ctx context.Context, name string, args []string, confirmed bool) (string, error) {
 	t, err := e.api.LookupTool(ctx, name)
 	if errors.Is(err, ipc.ErrToolNotFound) {
@@ -133,7 +144,15 @@ func (e *Executor) Exec(ctx context.Context, name string, args []string, confirm
 	if t.Status != "enabled" {
 		return "", ErrNotEnabled
 	}
-	if t.Destructive && !confirmed {
+	// The tier decides, not the column (Vikunja #449). RiskOf reads the row and
+	// answers the three questions the boolean never did: which acts are
+	// destructive, whether a confirm sticks (it never does), and what an
+	// unrecognised shape inherits (the confirm turn).
+	policy := PolicyFor(RiskOf(t))
+	if !policy.VoiceMayRun {
+		return "", ErrNeedsAuthedSurface
+	}
+	if policy.Confirm && !confirmed {
 		return "", ErrNeedsConfirm
 	}
 	// An MCP row is a call to a configured server, not a process. Everything