diff --git a/packages/bus/README.md b/packages/bus/README.md
index 75118426..bd5f65a7 100644
--- a/packages/bus/README.md
+++ b/packages/bus/README.md
@@ -122,9 +122,22 @@ Authorization requires the resolved option identified by `approvalChoice`
 Inbox projections expose `{action,target,approvalChoice}` as `authorization`:
 **S4 must display this context when offering resolution**, not infer approval
 from recommendation or option position. Any other option is a refusal, even if
-the decision is resolved. Approval is context-bound, not an exactly-once service
-operation receipt. S3/S6 must implement their own external-operation identity and
-uncertain-outcome handling. Raising/superseding and resolving are transactional.
+the decision is resolved. Every decision-backed authorization is single-use,
+including cross-role approval (lead decision 64). `authorize`, `message.send`
+and `role.revoke` share one authority-and-consumption helper. Each caller keeps
+the consumption check, `action.allowed` event and any broker-owned effect in one
+transaction.
+A later use through any of those paths, including after restart, refuses with
+`decision-consumed`. The `decision.raise` context event does not consume approval.
+A failed transaction rolls consumption back. A mismatch between the decision's
+recorded class and current policy refuses with `decision-mismatch` before use,
+in either direction. Within-role actions without a decision remain unchanged;
+explicitly supplying a decision subjects it to the same checks.
+
+A consumed approval is not an exactly-once external service operation receipt;
+an uncertain external outcome must not be retried with that approval. S3/S6
+must implement their own external-operation identity and uncertain-outcome
+handling. Raising/superseding and resolving are transactional.
 
 ## Human and reader paths
 
@@ -140,6 +153,12 @@ check: command and launch-registry checks still apply. All other read failures
 refuse, and the CLI itself must have a readable nonce environment.
 Reading `/proc` is Linux-specific. Reparenting and malicious same-UID PID/nonce
 impersonation remain within the explicit cooperative trust limit.
+Lead decision 62 accepts this limit for slice 1: the proof refuses a direct
+agent invocation, but deliberate detachment and environment clearing (as in
+Darkwing's `setsid -f env -i` probe) can obtain human authority. S6 must close
+this gap for managed agents with their own PID namespace or user and no human
+socket mounted. That isolation is not supplied by this S2 package. T3 seats
+must not invoke the human CLI or work around its proof.
 
 Human resolutions and launch toggles append `human.input`. Agent capabilities
 and read-only WebUI capabilities cannot reach these operations. Reader
diff --git a/packages/bus/src/broker.mjs b/packages/bus/src/broker.mjs
index 8c6347eb..43ce89e8 100644
--- a/packages/bus/src/broker.mjs
+++ b/packages/bus/src/broker.mjs
@@ -262,7 +262,7 @@ export class Broker {
     )
       fail('launch-revoked');
     const cls = this.#classification(s, action);
-    if (cls === 'within-role') return { class: cls };
+    if (cls === 'within-role' && !decision) return { class: cls };
     if (!decision) fail('decision-required');
     const d = this.#decision(s, decision),
       r = this.#closed(d.id);
@@ -273,6 +273,7 @@ export class Broker {
     );
     const context = evidence ? JSON.parse(evidence.body) : null;
     if (
+      d.class !== cls ||
       d.action !== action ||
       d.raised_by_role !== s.role ||
       d.raised_by_run !== s.run ||
@@ -285,19 +286,31 @@ export class Broker {
       fail('decision-mismatch');
     return { class: cls, decision: d.id };
   }
+  // Caller owns the transaction: authority, consumption and effect commit together.
+  #consumeAuthority(s, action, context = {}) {
+    const result = this.#checkAuthority(s, action, context);
+    // decision.raise records context, not permission consumed by an executor.
+    if (
+      result.decision &&
+      this.#store.get(
+        "SELECT 1 FROM events WHERE business=? AND kind='action.allowed' AND json_extract(body,'$.decision')=? AND json_extract(body,'$.operation') IS NOT 'decision.raise' LIMIT 1",
+        s.business,
+        result.decision,
+      )
+    )
+      fail('decision-consumed');
+    this.#event(
+      s,
+      'action.allowed',
+      { action, ...result, target: context.target ?? null },
+      context.target ?? null,
+    );
+    return result;
+  }
   // Trusted S3 handler calls inside its own operation; not a generic socket action executor.
   authorize(cap, action, context = {}) {
     const s = this.#session(cap);
-    return this.#store.transaction(() => {
-      const result = this.#checkAuthority(s, action, context);
-      this.#event(
-        s,
-        'action.allowed',
-        { action, ...result, target: context.target ?? null },
-        context.target ?? null,
-      );
-      return result;
-    });
+    return this.#store.transaction(() => this.#consumeAuthority(s, action, context));
   }
   // Trusted adapters only. No agent socket route reaches this method.
   recordEvent(cap, { kind, body, subject = null }) {
@@ -385,7 +398,7 @@ export class Broker {
         keys(a, ['role', 'decision'], ['role', 'decision']);
         identifier(a.role);
         identifier(a.decision);
-        this.#checkAuthority(s, 'role.revoke', { decision: a.decision, target: a.role });
+        this.#consumeAuthority(s, 'role.revoke', { decision: a.decision, target: a.role });
         const h = this.#holder(s.business, a.role);
         if (h?.op !== 'claim') fail('not-held');
         this.#claimEnd(s, h, 'revoke', a.decision);
@@ -539,7 +552,8 @@ export class Broker {
       }
       case 'message.send': {
         keys(a, ['to', 'body', 'class', 'in_reply_to', 'corrects', 'decision'], ['to', 'body']);
-        if (!s.human) this.#checkAuthority(s, 'message.send', { decision: a.decision ?? null, target: a.to });
+        if (!s.human)
+          this.#consumeAuthority(s, 'message.send', { decision: a.decision ?? null, target: a.to });
         else this.#human(s);
         if (a.to !== 'human' && !Object.hasOwn(b.roles, a.to)) fail('unknown-role');
         string(a.body, 32768);
diff --git a/packages/bus/tests/single-use.test.mjs b/packages/bus/tests/single-use.test.mjs
new file mode 100644
index 00000000..00aed1d9
--- /dev/null
+++ b/packages/bus/tests/single-use.test.mjs
@@ -0,0 +1,242 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { mkdtempSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { Store } from '../src/store.mjs';
+import { Broker } from '../src/broker.mjs';
+const businesses = {
+  demo: {
+    id: 'demo',
+    human: 'jason',
+    arbiters: { technical: 'cto', delivery: 'pm' },
+    roles: {
+      coder: { authority: { withinRole: ['message.send'], crossRole: ['task.scope.change'] } },
+      cto: { authority: { withinRole: [], crossRole: [] } },
+      pm: { authority: { withinRole: [], crossRole: [] } },
+    },
+  },
+};
+function fixture(t, gatedMessages = false) {
+  const root = mkdtempSync(join(tmpdir(), 'bus-once-'));
+  let store, b, cap, human;
+  const policy = structuredClone(businesses);
+  if (gatedMessages) policy.demo.roles.coder.authority.withinRole = [];
+  const call = (c, verb, args = {}) => b.request(c, { verb, args });
+  const bind = (run) => b.bindLaunch({ business: 'demo', role: 'coder', run, harness: 'pi', address: run });
+  function open() {
+    store = new Store(root);
+    b = new Broker({ store, businesses: policy });
+    cap = bind('run1');
+    human = b.bindHuman({ business: 'demo', human: 'jason', via: 'cli', outsideAgent: true });
+  }
+  open();
+  call(cap, 'role.claim');
+  t.after(() => {
+    store.close();
+    rmSync(root, { recursive: true, force: true });
+  });
+  function approve(action = 'deploy', domain = 'delivery', target = 'release1') {
+    const d = call(cap, 'decision.raise', {
+      action,
+      domain,
+      target,
+      question: 'Allow?',
+      options: [
+        { key: 'yes', text: 'Yes' },
+        { key: 'no', text: 'No' },
+      ],
+      recommendation: 'no',
+      blocking: false,
+    });
+    if (d.route_to === 'human') call(human, 'decision.resolve', { id: d.id, choice: 'yes' });
+    else {
+      const c = b.bindLaunch({ business: 'demo', role: 'cto', run: 'cto1', harness: 'pi', address: 'cto1' });
+      call(c, 'role.claim');
+      call(c, 'decision.resolve', { id: d.id, choice: 'yes' });
+    }
+    return d;
+  }
+  return {
+    get b() {
+      return b;
+    },
+    get store() {
+      return store;
+    },
+    get cap() {
+      return cap;
+    },
+    call,
+    bind,
+    approve,
+    use(d, c = cap) {
+      return b.authorize(c, d.action, { decision: d.id, target: d.authorization.target });
+    },
+    setPolicy(withinRole, crossRole) {
+      policy.demo.roles.coder.authority = { withinRole, crossRole };
+    },
+    narrowToCross(action) {
+      policy.demo.roles.coder.authority.crossRole.push(action);
+    },
+    reopen() {
+      store.close();
+      open();
+    },
+    count(d) {
+      return store.get(
+        "SELECT count(*) AS n FROM events WHERE kind='action.allowed' AND json_extract(body,'$.decision')=? AND json_extract(body,'$.operation') IS NOT 'decision.raise'",
+        d.id,
+      ).n;
+    },
+  };
+}
+test('gated approval authorizes once, survives store reopen, and fresh approval works', (t) => {
+  const f = fixture(t),
+    d = f.approve();
+  assert.equal(f.use(d).class, 'gated');
+  assert.equal(f.count(d), 1);
+  assert.throws(() => f.use(d), /decision-consumed/);
+  assert.equal(f.count(d), 1);
+  f.reopen();
+  assert.throws(() => f.use(d), /decision-consumed/);
+  const fresh = f.approve();
+  f.use(fresh);
+  assert.equal(f.count(fresh), 1);
+});
+test('another run cannot consume an approval; a failed check leaves it usable', (t) => {
+  const f = fixture(t),
+    d = f.approve(),
+    other = f.bind('run2');
+  f.call(f.cap, 'role.release');
+  f.call(other, 'role.claim');
+  assert.throws(() => f.use(d, other), /decision-mismatch/);
+  assert.equal(f.count(d), 0);
+  f.call(other, 'role.release');
+  f.call(f.cap, 'role.claim');
+  assert.throws(
+    () => f.b.authorize(f.cap, 'deploy', { decision: d.id, target: 'other' }),
+    /decision-mismatch/,
+  );
+  f.use(d);
+  assert.equal(f.count(d), 1);
+});
+test('two scheduled callers have exactly one grant and one consumed refusal', async (t) => {
+  const f = fixture(t),
+    d = f.approve();
+  const results = await Promise.allSettled([
+    Promise.resolve().then(() => f.use(d)),
+    Promise.resolve().then(() => f.use(d)),
+  ]);
+  assert.equal(results.filter((r) => r.status === 'fulfilled').length, 1);
+  assert.equal(results.find((r) => r.status === 'rejected').reason.code, 'decision-consumed');
+  assert.equal(f.count(d), 1);
+});
+test('failed commit rolls consumption back; cross-role consumes and within-role stays reusable', (t) => {
+  const f = fixture(t),
+    d = f.approve(),
+    transaction = f.store.transaction.bind(f.store);
+  f.store.transaction = (fn) =>
+    transaction(() => {
+      fn();
+      throw Error('fixture rollback');
+    });
+  assert.throws(() => f.use(d), /fixture rollback/);
+  f.store.transaction = transaction;
+  assert.equal(f.count(d), 0);
+  f.use(d);
+  const cross = f.approve('task.scope.change', 'technical');
+  f.use(cross);
+  assert.throws(() => f.use(cross), /decision-consumed/);
+  f.reopen();
+  assert.throws(() => f.use(cross), /decision-consumed/);
+  assert.equal(f.count(cross), 1);
+  for (let n = 0; n < 2; n++) assert.equal(f.b.authorize(f.cap, 'message.send').class, 'within-role');
+  const within = f.call(f.cap, 'decision.raise', {
+    action: 'message.send',
+    question: 'Send?',
+    options: [
+      { key: 'yes', text: 'Yes' },
+      { key: 'no', text: 'No' },
+    ],
+    recommendation: 'yes',
+    choice: 'yes',
+    blocking: false,
+  });
+  assert.equal(within.route_to, 'coder');
+  f.use(within);
+  assert.throws(() => f.use(within), /decision-consumed/);
+  assert.equal(f.count(within), 1);
+});
+
+for (const [from, to] of [
+  ['gated', 'cross-role'],
+  ['cross-role', 'gated'],
+  ['gated', 'within-role'],
+  ['cross-role', 'within-role'],
+  ['within-role', 'gated'],
+  ['within-role', 'cross-role'],
+]) {
+  test(`class drift ${from} to ${to} refuses before consumption`, (t) => {
+    const f = fixture(t),
+      action = 'task.priority.change';
+    f.setPolicy(from === 'within-role' ? [action] : [], from === 'cross-role' ? [action] : []);
+    f.reopen();
+    let d;
+    if (from === 'within-role')
+      d = f.call(f.cap, 'decision.raise', {
+        action,
+        target: 'release1',
+        question: 'Allow?',
+        options: [
+          { key: 'yes', text: 'Yes' },
+          { key: 'no', text: 'No' },
+        ],
+        recommendation: 'yes',
+        choice: 'yes',
+        blocking: false,
+      });
+    else d = f.approve(action, 'technical');
+    f.setPolicy(to === 'within-role' ? [action] : [], to === 'cross-role' ? [action] : []);
+    f.reopen();
+    assert.throws(() => f.use(d), /decision-mismatch/);
+    assert.equal(f.count(d), 0);
+  });
+}
+test('message.send consumes approval and prevents a later send or authorize', (t) => {
+  const f = fixture(t, true),
+    d = f.approve('message.send', 'delivery', 'pm');
+  // Invalid effect must roll the consumption insert back with the message.
+  assert.throws(() => f.call(f.cap, 'message.send', { to: 'pm', body: '', decision: d.id }), /invalid/);
+  assert.equal(f.count(d), 0);
+  f.call(f.cap, 'message.send', { to: 'pm', body: 'once', decision: d.id });
+  assert.equal(f.count(d), 1);
+  assert.throws(
+    () => f.call(f.cap, 'message.send', { to: 'pm', body: 'twice', decision: d.id }),
+    /decision-consumed/,
+  );
+  assert.throws(() => f.use(d), /decision-consumed/);
+  assert.equal(f.store.get('SELECT count(*) AS n FROM messages').n, 1);
+  const fresh = f.approve('message.send', 'delivery', 'pm');
+  f.use(fresh);
+  assert.throws(
+    () => f.call(f.cap, 'message.send', { to: 'pm', body: 'after authorize', decision: fresh.id }),
+    /decision-consumed/,
+  );
+});
+test('role.revoke consumes approval and prevents a later revoke or authorize', (t) => {
+  const f = fixture(t),
+    pm = f.b.bindLaunch({ business: 'demo', role: 'pm', run: 'pm1', harness: 'pi', address: 'pm1' });
+  f.call(pm, 'role.claim');
+  const d = f.approve('role.revoke', 'delivery', 'pm');
+  f.call(f.cap, 'role.revoke', { role: 'pm', decision: d.id });
+  assert.equal(f.count(d), 1);
+  assert.throws(() => f.call(f.cap, 'role.revoke', { role: 'pm', decision: d.id }), /decision-consumed/);
+  assert.throws(() => f.use(d), /decision-consumed/);
+  assert.equal(f.store.get("SELECT count(*) AS n FROM role_claims WHERE op='revoke'").n, 1);
+  const next = f.b.bindLaunch({ business: 'demo', role: 'pm', run: 'pm2', harness: 'pi', address: 'pm2' });
+  f.call(next, 'role.claim');
+  const fresh = f.approve('role.revoke', 'delivery', 'pm');
+  f.use(fresh);
+  assert.throws(() => f.call(f.cap, 'role.revoke', { role: 'pm', decision: fresh.id }), /decision-consumed/);
+});