diff --git a/alembic/versions/0090_rule_verification.py b/alembic/versions/0090_rule_verification.py
new file mode 100644
index 0000000..0ba64a9
--- /dev/null
+++ b/alembic/versions/0090_rule_verification.py
@@ -0,0 +1,64 @@
+"""a rule can carry its own check — verify_with, expires_when, verified_at
+(milestone 312 step 1)
+
+Revision ID: 0090
+Revises: 0089
+Create Date: 2026-08-27
+
+A rulebook holds two kinds of row in one table. A NORM is a decision: it has
+no truth value, and it changes only when its author changes it — which they
+know they did. A CONSTRAINT is a fact about someone else's software: a
+runner's shell, a bot's config, a tool that exists. Nobody is present when
+that goes false.
+
+Milestone 307's rulebook audit found nine stale sites. Every one was a
+constraint; not one norm had rotted. One of them had been telling every
+session to skip database-backed tests for weeks while the integration lane
+sat green in the workflow.
+
+Three nullable columns, so a rule can say how to check itself:
+
+- `verify_with` — how to tell whether this is still true. A command, a path,
+  a URL, a query. Prose is allowed; something runnable is better.
+- `expires_when` — the STATE under which it stops being true. Deliberately
+  not a date: constraints do not expire on a schedule, they expire when the
+  world underneath them moves.
+- `verified_at` — when the check last passed. NULL means never checked, and
+  sorts FIRST in the sweep: unexamined outranks examined-long-ago.
+
+All three nullable and all three optional, because most rules should set
+none of them. A null `verify_with` is not an omission — it is the honest
+marker of "this one is a decision, and there is nothing to go and check."
+That signal only works if the field stays empty wherever it belongs empty.
+
+No CHECK constraint is involved, so rule 36 does not apply here. Nothing is
+backfilled: a migration cannot invent a check any more than 0088 could
+invent a trigger.
+"""
+import sqlalchemy as sa
+from alembic import op
+
+revision = "0090"
+down_revision = "0089"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("rules", sa.Column("verify_with", sa.Text(), nullable=True))
+    op.add_column("rules", sa.Column("expires_when", sa.Text(), nullable=True))
+    op.add_column(
+        "rules",
+        sa.Column("verified_at", sa.DateTime(timezone=True), nullable=True),
+    )
+    # No index on (verify_with, verified_at). The sweep this exists for reads
+    # an operator's whole rulebook — hundreds of rows, not millions — and runs
+    # when a human asks for it, never on a request path. An index here would
+    # be maintained on every rule write to serve a query that a sequential
+    # scan answers instantly.
+
+
+def downgrade() -> None:
+    op.drop_column("rules", "verified_at")
+    op.drop_column("rules", "expires_when")
+    op.drop_column("rules", "verify_with")
diff --git a/alembic/versions/0091_task_kind_spike.py b/alembic/versions/0091_task_kind_spike.py
new file mode 100644
index 0000000..5b03374
--- /dev/null
+++ b/alembic/versions/0091_task_kind_spike.py
@@ -0,0 +1,66 @@
+"""task_kind gains 'spike' — the investigation, not the change
+(milestone 312 step 5)
+
+Revision ID: 0091
+Revises: 0090
+Create Date: 2026-08-27
+
+A spike is a task shape the others cannot hold. `work` ships a change;
+`issue` fixes something broken. A spike is time-boxed and its output is
+KNOWLEDGE — it succeeds by producing an answer, and nothing ships at the
+end of it. "Find out whether the runner can be given a bash shell" is not
+work, and filing it as work makes a finished investigation look like an
+abandoned change.
+
+It is the record a failed check asks for. Milestone 312 gave rules a
+`verify_with`; when one of those fails, the rule is wrong and the next move
+is often to go and find out what replaced it. `notes.arose_from_id` already
+exists (0065), so that constraint -> spike link needs no further schema.
+
+Rule 36: `task_kind` is gated by a CHECK whitelist, so the value and the
+widened constraint land in the SAME migration — DROP then ADD, exactly as
+0065 did when it introduced 'issue'. Adding the value and constraining it
+later leaves a window where the database accepts anything.
+
+'plan' stays in the list though it is retired (plans are milestones since
+0066): historical plan-tasks still carry it, and dropping it from the
+whitelist would make old rows unwritable.
+"""
+from alembic import op
+
+revision = "0091"
+down_revision = "0090"
+branch_labels = None
+depends_on = None
+
+# One tuple so the upgrade and the downgrade cannot disagree about what the
+# list was on either side of this migration.
+_KINDS_AFTER = ("work", "plan", "issue", "spike")
+_KINDS_BEFORE = ("work", "plan", "issue")
+
+
+# Restated rather than imported from 0088, which has the same helper. A
+# migration is a snapshot: it must keep working when the code around it has
+# moved on, so it never imports from live modules or from its siblings. Six
+# duplicated lines are the price of that, and the cheap half of the bargain.
+def _in_list(values: tuple[str, ...]) -> str:
+    return "task_kind IN (" + ", ".join(f"'{v}'" for v in values) + ")"
+
+
+def upgrade() -> None:
+    op.drop_constraint("notes_task_kind_check", "notes", type_="check")
+    op.create_check_constraint(
+        "notes_task_kind_check", "notes", _in_list(_KINDS_AFTER),
+    )
+
+
+def downgrade() -> None:
+    # Any row already filed as a spike would violate the narrowed constraint,
+    # so they are demoted to 'work' first. Lossy and deliberately so: the
+    # alternative is a downgrade that fails on real data, which is worse than
+    # a downgrade that says what it did.
+    op.execute("UPDATE notes SET task_kind = 'work' WHERE task_kind = 'spike'")
+    op.drop_constraint("notes_task_kind_check", "notes", type_="check")
+    op.create_check_constraint(
+        "notes_task_kind_check", "notes", _in_list(_KINDS_BEFORE),
+    )
diff --git a/frontend/src/api/rulebooks.ts b/frontend/src/api/rulebooks.ts
index 2c3eb8c..f884999 100644
--- a/frontend/src/api/rulebooks.ts
+++ b/frontend/src/api/rulebooks.ts
@@ -55,6 +55,16 @@ export interface Rule {
   tier: RuleTier;
   why: string;
   how_to_apply: string;
+  /**
+   * How to check the rule is still true, and the state that ends it. Set
+   * only on a rule that asserts a fact about something outside the
+   * operator's control; empty on a rule that is a decision, which is most
+   * of them. Empty is meaningful, not missing.
+   */
+  verify_with: string;
+  expires_when: string;
+  /** When the check last passed. Null means never checked. */
+  verified_at: string | null;
   /** The note or task that caused this rule, if one was recorded. */
   arose_from_id: number | null;
   order_index: number;
@@ -80,6 +90,12 @@ export interface RuleHeader {
   updated_at: string | null;
   when_to_apply?: string;
   arose_from_id?: number;
+  /**
+   * Present ONLY on a rule that carries a check — the presence of the key
+   * is itself the signal that this rule asserts a fact that can go false.
+   * A date (YYYY-MM-DD), or the literal "never".
+   */
+  last_verified?: string;
 }
 
 export interface ApplicableRules {
@@ -170,7 +186,14 @@ export async function getRule(id: number): Promise<Rule> {
   return apiGet(`/api/rules/${id}`);
 }
 
-/** The fields both write paths accept. `system_ids` REPLACES a rule's areas. */
+/**
+ * The fields both write paths accept. `system_ids` REPLACES a rule's areas.
+ *
+ * Sending "" for a nullable text field CLEARS it here — the server maps an
+ * empty string to NULL, so an emptied form input does what it looks like it
+ * does. (The MCP door reads "" as "leave unchanged" and needs an explicit
+ * clear_fields list instead; the two idioms reach the same state.)
+ */
 export interface RuleWrite {
   title: string;
   statement: string;
@@ -181,6 +204,8 @@ export interface RuleWrite {
   order_index: number;
   system_ids: number[];
   arose_from_id: number | null;
+  verify_with: string;
+  expires_when: string;
 }
 
 export async function createRule(topicId: number, data: Partial<RuleWrite> & { title: string; statement: string }): Promise<Rule> {
@@ -256,3 +281,59 @@ export async function includeAlwaysOnRulebook(projectId: number, rulebookId: num
   await apiDelete(`/api/projects/${projectId}/exclusions/rulebooks/${rulebookId}`);
 }
 
+
+/**
+ * One row of the staleness sweep. Unlike RuleHeader this carries the CHECK
+ * in full — the reader is about to go and run it, so the text is the point
+ * of the payload rather than the bloat a listing avoids.
+ */
+export interface RuleVerificationRow {
+  id: number;
+  title: string;
+  statement: string;
+  tier: RuleTier;
+  topic_id: number | null;
+  project_id: number | null;
+  when_to_apply: string;
+  verify_with: string;
+  expires_when: string;
+  /** A date (YYYY-MM-DD), or the literal "never". */
+  last_verified: string | null;
+  /** Null when never verified — "never" is not zero days ago. */
+  days_since_verified: number | null;
+}
+
+/**
+ * Rules asserting a fact that may have gone false, oldest verification
+ * first, never-checked at the top. Rules without a check never appear:
+ * they are decisions, and there is nothing to go and check.
+ *
+ * Not filterable by project — a project reaches rules through project
+ * scope, subscriptions, always-on rulebooks and exclusions, and a filter
+ * missing one of those paths would under-report.
+ */
+export async function listRulesDueForVerification(opts: {
+  olderThanDays?: number;
+  tier?: RuleTier;
+  neverOnly?: boolean;
+} = {}): Promise<{ rules: RuleVerificationRow[]; total: number }> {
+  const q = new URLSearchParams();
+  if (opts.olderThanDays) q.set("older_than_days", String(opts.olderThanDays));
+  if (opts.tier) q.set("tier", opts.tier);
+  if (opts.neverOnly) q.set("never_only", "true");
+  const qs = q.toString();
+  return apiGet(`/api/rules-due-for-verification${qs ? `?${qs}` : ""}`);
+}
+
+/**
+ * Record that a rule's check was RUN, and what it said.
+ *
+ * `stillTrue: false` writes nothing on purpose — a rule whose check failed
+ * is not in a recordable state, it is wrong — so it stays at the top of the
+ * sweep until someone corrects or retires it.
+ */
+export async function markRuleVerified(
+  id: number, stillTrue = true,
+): Promise<Rule & { verified: boolean }> {
+  return apiPost(`/api/rules/${id}/verify`, { still_true: stillTrue });
+}
diff --git a/frontend/src/assets/rules-shared.css b/frontend/src/assets/rules-shared.css
index 9efc62b..72c1448 100644
--- a/frontend/src/assets/rules-shared.css
+++ b/frontend/src/assets/rules-shared.css
@@ -1,5 +1,7 @@
-/* Shared by the three rules panes (RulebookListPane, RuleListPane,
-   RulebookDetailPane): the pane surface and its heading. Load with
+/* Shared by the rules panes (RulebookListPane, RuleListPane,
+   RulebookDetailPane, RuleSweepPane): the pane surface, its heading, and the
+   title chip. Counting them in this comment went stale the first time a
+   fourth was added, so it no longer does. Load with
    <style src="@/assets/rules-shared.css" /> beside the component's own
    scoped block; never restate these there (#2903, milestone 299). */
 .pane {
@@ -13,3 +15,19 @@
   margin: 0 0 0.5rem 0;
 }
 .form-buttons { display: flex; gap: 0.5rem; }
+
+/* A small marker beside a rule's title. Two of these appeared within one
+   milestone (tier, then verification) and were byte-identical; a third would
+   have drifted. The pane's italic serif title is inherited by anything inside
+   it, so the chip resets family and style explicitly. */
+.rule-chip {
+  margin-left: 0.4rem;
+  font-family: var(--fs-font-body);
+  font-style: normal;
+  font-size: 0.62rem;
+  color: var(--fs-text-secondary);
+  background: var(--fs-surface-raised);
+  border-radius: var(--fs-radius-pill);
+  padding: 0.05rem 0.4rem;
+  vertical-align: middle;
+}
diff --git a/frontend/src/components/rules/ProjectRulesTab.vue b/frontend/src/components/rules/ProjectRulesTab.vue
index 8fdd3fb..db69979 100644
--- a/frontend/src/components/rules/ProjectRulesTab.vue
+++ b/frontend/src/components/rules/ProjectRulesTab.vue
@@ -24,7 +24,10 @@ const allRulebooks = ref<Rulebook[]>([]);
 const showPicker = ref(false);
 const expandedRuleIds = ref<Set<number>>(new Set());
 
-const ruleDetails = ref<Record<number, { why: string; how_to_apply: string }>>({});
+const ruleDetails = ref<Record<number, {
+  why: string; how_to_apply: string;
+  verify_with: string; expires_when: string; verified_at: string | null;
+}>>({});
 
 const showProjectRuleForm = ref(false);
 const newProjectRule = ref({
@@ -67,6 +70,9 @@ async function toggleRuleExpand(ruleId: number) {
       ruleDetails.value[ruleId] = {
         why: rule.why || "",
         how_to_apply: rule.how_to_apply || "",
+        verify_with: rule.verify_with || "",
+        expires_when: rule.expires_when || "",
+        verified_at: rule.verified_at,
       };
     }
   }
@@ -74,6 +80,11 @@ async function toggleRuleExpand(ruleId: number) {
   expandedRuleIds.value = new Set(expandedRuleIds.value);
 }
 
+/** "never run" reads as a stronger claim than an absent date — and it is. */
+function checkAge(verifiedAt: string | null): string {
+  return verifiedAt ? `last passed ${verifiedAt.slice(0, 10)}` : "never run";
+}
+
 function openInRulesView(rulebookId: number, ruleId?: number) {
   const query: Record<string, string> = { rb: String(rulebookId) };
   if (ruleId) query.rule = String(ruleId);
@@ -279,6 +290,16 @@ watch(() => props.projectId, load);
             <div v-if="ruleDetails[r.id].how_to_apply">
               <strong>How to apply:</strong> {{ ruleDetails[r.id].how_to_apply }}
             </div>
+            <!-- Shown only when the rule carries a check. Read-only here: this
+                 tab is the project's view of what binds it, and editing a rule
+                 belongs on the rulebook surface that owns it. -->
+            <div v-if="ruleDetails[r.id].verify_with">
+              <strong>Check:</strong> {{ ruleDetails[r.id].verify_with }}
+              <span class="rule-check-age">{{ checkAge(ruleDetails[r.id].verified_at) }}</span>
+            </div>
+            <div v-if="ruleDetails[r.id].expires_when">
+              <strong>Ends when:</strong> {{ ruleDetails[r.id].expires_when }}
+            </div>
             <button class="delete-link" @click="removeProjectRule(r.id)">Delete</button>
           </div>
         </li>
@@ -332,6 +353,13 @@ watch(() => props.projectId, load);
                 <div v-if="ruleDetails[r.id].how_to_apply">
                   <strong>How to apply:</strong> {{ ruleDetails[r.id].how_to_apply }}
                 </div>
+                <div v-if="ruleDetails[r.id].verify_with">
+                  <strong>Check:</strong> {{ ruleDetails[r.id].verify_with }}
+                  <span class="rule-check-age">{{ checkAge(ruleDetails[r.id].verified_at) }}</span>
+                </div>
+                <div v-if="ruleDetails[r.id].expires_when">
+                  <strong>Ends when:</strong> {{ ruleDetails[r.id].expires_when }}
+                </div>
                 <button
                   class="edit-link"
                   @click="openInRulesView(r.rulebook_id, r.id)"
@@ -428,6 +456,11 @@ ul { list-style: none; padding: 0; margin: 0; }
 }
 .rule-head { cursor: pointer; }
 .rule-title { font-weight: 500; }
+.rule-check-age {
+  margin-left: var(--fs-space-2);
+  color: var(--fs-text-tertiary);
+  font-variant-numeric: tabular-nums;
+}
 .rule-statement { display: block; opacity: 0.85; margin-top: 0.25rem; }
 .rule-detail {
   margin-top: 0.5rem; padding: 0.5rem;
diff --git a/frontend/src/components/rules/RuleEditorSlideOver.vue b/frontend/src/components/rules/RuleEditorSlideOver.vue
index 16e420b..26523bf 100644
--- a/frontend/src/components/rules/RuleEditorSlideOver.vue
+++ b/frontend/src/components/rules/RuleEditorSlideOver.vue
@@ -16,6 +16,8 @@ const tier = ref<RuleTier>("always_on");
 const systemIds = ref<number[]>([]);
 const why = ref("");
 const howToApply = ref("");
+const verifyWith = ref("");
+const expiresWhen = ref("");
 
 const relations = computed(() => store.currentRule?.relations ?? []);
 
@@ -38,6 +40,27 @@ function toggleSystem(id: number) {
 
 const isCreating = ref(props.ruleId === null);
 
+// The stored stamp, not the draft: it describes the check that was RUN, and
+// an unsaved edit to the textarea has not been run against anything.
+const verifiedAt = computed(() => store.currentRule?.verified_at ?? null);
+const savedCheck = computed(() => store.currentRule?.verify_with ?? "");
+// Built here rather than in the template: same shape as the server's
+// last_verified_label, and it keeps the null-narrowing in TypeScript's reach.
+const stampLabel = computed(() =>
+  verifiedAt.value ? `Last checked ${verifiedAt.value.slice(0, 10)}` : "Never checked",
+);
+const verifying = ref(false);
+
+async function verify(stillTrue: boolean) {
+  if (props.ruleId === null) return;
+  verifying.value = true;
+  try {
+    await store.verifyRule(props.ruleId, stillTrue);
+  } finally {
+    verifying.value = false;
+  }
+}
+
 async function load() {
   if (props.ruleId !== null) {
     await store.fetchRule(props.ruleId);
@@ -50,6 +73,8 @@ async function load() {
       systemIds.value = (r.systems ?? []).map((sys) => sys.id);
       why.value = r.why || "";
       howToApply.value = r.how_to_apply || "";
+      verifyWith.value = r.verify_with || "";
+      expiresWhen.value = r.expires_when || "";
     }
   } else {
     title.value = "";
@@ -59,6 +84,8 @@ async function load() {
     systemIds.value = [];
     why.value = "";
     howToApply.value = "";
+    verifyWith.value = "";
+    expiresWhen.value = "";
   }
   await canon.fetchCatalog();
 }
@@ -78,6 +105,11 @@ async function save() {
     system_ids: systemIds.value,
     why: why.value,
     how_to_apply: howToApply.value,
+    // Always sent, including empty. The REST door maps "" to NULL, so
+    // clearing a field here actually clears it — the MCP door's "" means
+    // "leave unchanged" and needs an explicit clear_fields list instead.
+    verify_with: verifyWith.value,
+    expires_when: expiresWhen.value,
   };
   if (isCreating.value && props.topicId !== null) {
     await store.createRule(props.topicId, fields);
@@ -162,6 +194,45 @@ watch(() => props.ruleId, load);
         </p>
       </fieldset>
 
+      <fieldset class="check">
+        <legend>Can this rule go stale?</legend>
+        <p class="tier-test intro">
+          Most rules are <em>decisions</em> — they have no truth value and change only when you
+          change them. Leave this empty for those. Fill it in when the rule asserts a
+          <em>fact</em> about something outside your control, because those go false quietly.
+        </p>
+        <label>
+          How to check it is still true
+          <textarea
+            v-model="verifyWith"
+            rows="2"
+            placeholder="A command, a path, a query — something runnable beats prose."
+          />
+        </label>
+        <label>
+          What would end it
+          <textarea
+            v-model="expiresWhen"
+            rows="2"
+            placeholder="A state, not a date — “when the runner can be given a bash shell”."
+          />
+        </label>
+
+        <div v-if="savedCheck" class="stamp">
+          <span class="stamp-age" :class="{ unchecked: !verifiedAt }">{{ stampLabel }}</span>
+          <span class="stamp-actions">
+            <button type="button" :disabled="verifying" @click="verify(true)">Still true</button>
+            <button type="button" :disabled="verifying" @click="verify(false)">No longer true</button>
+          </span>
+        </div>
+        <p v-if="savedCheck" class="tier-test">
+          Record this after actually running the check, never on the strength of the rule
+          sounding plausible. “No longer true” deliberately stores nothing — the rule is wrong,
+          not in a state worth recording, so it stays at the top of the sweep until you fix or
+          retire it.
+        </p>
+      </fieldset>
+
       <section v-if="relations.length" class="relations">
         <h3>Related rules</h3>
         <ul>
@@ -231,6 +302,35 @@ legend { padding: 0 0.35rem; font-size: 0.8rem; color: var(--fs-text-tertiary);
 .relation-target { color: var(--fs-text-primary); }
 .relation-note { width: 100%; font-size: 0.78rem; color: var(--fs-text-tertiary); }
 
+/* A real base rule, not just descendants: the dangling-style check reads a
+   class that only ever appears as an ancestor as a half-deleted rule, and it
+   is right to — an element whose appearance comes only from its tag is one
+   `fieldset {}` edit away from being unstyled. */
+.check { margin-bottom: 1rem; }
+.check .intro { margin-top: 0; margin-bottom: 0.75rem; }
+.check label { margin-bottom: 0.75rem; }
+.stamp {
+  display: flex; align-items: center; gap: var(--fs-space-2);
+  flex-wrap: wrap;
+  margin-top: 0.25rem;
+}
+.stamp-age { font-size: 0.8rem; color: var(--fs-text-secondary); font-variant-numeric: tabular-nums; }
+/* Never-checked is INFORMATION, not an error: it is the ordinary starting
+   state of every constraint anyone has just written. --fs-overdue (error red)
+   is reserved for a broken promise like a missed due date; a verification age
+   is not one, and colouring it that way would make a brand-new rule look
+   broken. Secondary text, weighted normally. */
+.stamp-age.unchecked { color: var(--fs-text-tertiary); font-style: italic; }
+.stamp-actions { display: flex; gap: var(--fs-space-2); margin-left: auto; }
+.stamp-actions button {
+  cursor: pointer; font: inherit; font-size: 0.78rem;
+  background: var(--fs-surface-raised); color: var(--fs-text-primary);
+  border: 1px solid var(--fs-border-color); border-radius: var(--fs-radius-sm);
+  padding: 0.2rem 0.55rem;
+}
+.stamp-actions button:hover:not(:disabled) { background: var(--fs-surface-hover); }
+.stamp-actions button:disabled { opacity: var(--fs-disabled-opacity); cursor: default; }
+
 .trash, .close { background: none; border: none; cursor: pointer; opacity: 0.6; font-size: 1.25em; }
 .trash:hover, .close:hover { opacity: 1; }
 </style>
diff --git a/frontend/src/components/rules/RuleListPane.vue b/frontend/src/components/rules/RuleListPane.vue
index 78ba14a..6c2a662 100644
--- a/frontend/src/components/rules/RuleListPane.vue
+++ b/frontend/src/components/rules/RuleListPane.vue
@@ -17,7 +17,17 @@ const emit = defineEmits<{
           {{ r.title }}
           <!-- Only conditional is marked: always-on is the default and
                badging every row would say nothing. -->
-          <span v-if="r.tier === 'conditional'" class="tier-chip" title="Arrives when its trigger fires, rather than in every session">conditional</span>
+          <span v-if="r.tier === 'conditional'" class="rule-chip" title="Arrives when its trigger fires, rather than in every session">conditional</span>
+          <!-- Present only on a rule carrying a check, so the chip's very
+               presence says "this one asserts a fact that can go false". -->
+          <span
+            v-if="r.last_verified"
+            class="rule-chip check-chip"
+            :class="{ unchecked: r.last_verified === 'never' }"
+            :title="r.last_verified === 'never'
+              ? 'Asserts a fact nobody has confirmed yet'
+              : `Check last passed ${r.last_verified}`"
+          >{{ r.last_verified === "never" ? "unverified" : `checked ${r.last_verified}` }}</span>
         </div>
         <div class="statement">{{ r.statement }}</div>
         <div v-if="r.when_to_apply || r.updated_at" class="meta">
@@ -47,16 +57,13 @@ li:hover { background: var(--fs-surface-hover); }
 .meta { display: flex; align-items: baseline; gap: 0.5rem; margin-top: 0.35rem; font-size: 0.75em; }
 .trigger { flex: 1; min-width: 0; color: var(--fs-text-secondary); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
 .age { color: var(--fs-text-tertiary); font-variant-numeric: tabular-nums; flex-shrink: 0; }
-.tier-chip {
-  margin-left: 0.4rem;
-  font-family: var(--fs-font-body);
-  font-style: normal;
-  font-size: 0.62rem;
-  color: var(--fs-text-secondary);
-  background: var(--fs-surface-raised);
-  border-radius: var(--fs-radius-pill);
-  padding: 0.05rem 0.4rem;
-  vertical-align: middle;
-}
+/* Only the departures from .rule-chip (rules-shared.css) live here. */
+.check-chip { font-variant-numeric: tabular-nums; }
+/* No age-graded colour on purpose. The sweep is already ordered by urgency, so
+   a red/amber ramp would restate the ordering AND require an invented "stale
+   after N days" threshold — a magic number nobody could defend and the first
+   thing to go out of date. Only "never" is marked, because it is categorically
+   different from a date rather than a worse one. */
+.check-chip.unchecked { font-style: italic; color: var(--fs-text-tertiary); }
 .new-rule { cursor: pointer; }
 </style>
diff --git a/frontend/src/components/rules/RuleSweepPane.vue b/frontend/src/components/rules/RuleSweepPane.vue
new file mode 100644
index 0000000..f072500
--- /dev/null
+++ b/frontend/src/components/rules/RuleSweepPane.vue
@@ -0,0 +1,180 @@
+<script setup lang="ts">
+/**
+ * The staleness sweep: rules that assert a FACT, oldest verification first.
+ *
+ * Cross-cutting by nature — a rule that has gone false does not care which
+ * rulebook it sits in — so this is its own pane rather than a filter on the
+ * per-topic rule list. That list can only ever show one topic of one
+ * rulebook, so filtering it would quietly under-report, which is the exact
+ * failure this surface exists to catch.
+ */
+import { onMounted, ref } from "vue";
+import { useRulebooksStore } from "@/stores/rulebooks";
+import type { RuleTier } from "@/api/rulebooks";
+
+const emit = defineEmits<{ "open-rule": [id: number] }>();
+
+const store = useRulebooksStore();
+const neverOnly = ref(false);
+const tier = ref<RuleTier | "">("");
+const busyId = ref<number | null>(null);
+
+function reload() {
+  return store.fetchRulesDue({
+    neverOnly: neverOnly.value || undefined,
+    tier: tier.value || undefined,
+  });
+}
+
+async function verify(id: number, stillTrue: boolean) {
+  busyId.value = id;
+  try {
+    await store.verifyRule(id, stillTrue);
+  } finally {
+    busyId.value = null;
+  }
+}
+
+onMounted(reload);
+</script>
+
+<template>
+  <section class="pane sweep">
+    <header>
+      <h2>Due for verification</h2>
+      <p class="lede">
+        Rules that assert a fact about something outside your control. Most rules are
+        decisions and never appear here — they have no truth value to go stale.
+      </p>
+    </header>
+
+    <div class="filters">
+      <label class="filter">
+        <input v-model="neverOnly" type="checkbox" @change="reload" />
+        <span>Never checked only</span>
+      </label>
+      <label class="filter">
+        <span>Tier</span>
+        <select v-model="tier" @change="reload">
+          <option value="">any</option>
+          <option value="always_on">always on</option>
+          <option value="conditional">conditional</option>
+        </select>
+      </label>
+    </div>
+
+    <p v-if="store.loading" class="state">Loading…</p>
+
+    <!-- An empty sweep is GOOD NEWS, and must not read like a broken page. -->
+    <p v-else-if="!store.rulesDue.length" class="state empty">
+      Nothing to check.
+      {{ neverOnly || tier ? "No rule matches these filters." : "No rule carries a check yet — add one to a rule that asserts a fact." }}
+    </p>
+
+    <ol v-else class="rows">
+      <li v-for="r in store.rulesDue" :key="r.id" class="row">
+        <div class="row-head">
+          <button class="row-title" @click="emit('open-rule', r.id)">{{ r.title }}</button>
+          <span v-if="r.tier === 'always_on'" class="rule-chip" title="Loaded into every session — a wrong one is wrong everywhere at once">always on</span>
+          <span class="age" :class="{ unchecked: r.days_since_verified === null }">
+            {{ r.days_since_verified === null
+              ? "never checked"
+              : `${r.days_since_verified}d ago` }}
+          </span>
+        </div>
+
+        <p class="statement">{{ r.statement }}</p>
+
+        <dl class="check">
+          <dt>Check</dt>
+          <dd><code>{{ r.verify_with }}</code></dd>
+          <template v-if="r.expires_when">
+            <dt>Ends when</dt>
+            <dd>{{ r.expires_when }}</dd>
+          </template>
+        </dl>
+
+        <div class="actions">
+          <button :disabled="busyId === r.id" @click="verify(r.id, true)">Still true</button>
+          <button :disabled="busyId === r.id" @click="verify(r.id, false)">No longer true</button>
+        </div>
+      </li>
+    </ol>
+
+    <p v-if="store.rulesDue.length" class="footnote">
+      Record a result only after actually running the check. “No longer true” stores nothing
+      on purpose — the rule is wrong rather than in a state worth recording, so it keeps its
+      place here until you correct or retire it.
+    </p>
+  </section>
+</template>
+
+<style src="@/assets/rules-shared.css" />
+<style scoped>
+.sweep { display: flex; flex-direction: column; gap: var(--fs-space-3); }
+.lede {
+  margin: 0;
+  max-width: 62ch;
+  font-size: 0.85rem;
+  color: var(--fs-text-secondary);
+  line-height: 1.5;
+}
+
+.filters { display: flex; gap: var(--fs-space-5); align-items: center; flex-wrap: wrap; }
+.filter { display: flex; align-items: center; gap: var(--fs-space-2); font-size: 0.82rem; color: var(--fs-text-secondary); }
+.filter input[type="checkbox"] { accent-color: var(--fs-accent); }
+.filter select {
+  font: inherit; font-size: 0.82rem;
+  background: var(--fs-surface-page); color: var(--fs-text-primary);
+  border: 1px solid var(--fs-border-color); border-radius: var(--fs-radius-md);
+  padding: 0.2rem 0.4rem;
+}
+
+.state { margin: 0; font-size: 0.9rem; color: var(--fs-text-secondary); }
+.state.empty { color: var(--fs-text-tertiary); }
+
+.rows { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: var(--fs-space-3); }
+.row {
+  background: var(--fs-surface-raised);
+  border-radius: var(--fs-radius-md);
+  padding: var(--fs-space-3);
+}
+.row-head { display: flex; align-items: baseline; gap: var(--fs-space-2); flex-wrap: wrap; }
+.row-title {
+  background: none; border: none; padding: 0; cursor: pointer;
+  font-family: Fraunces, serif; font-style: italic; font-size: 1.02rem;
+  color: var(--fs-text-primary); text-align: left;
+}
+.row-title:hover { text-decoration: underline; }
+/* The ORDER carries urgency — the top of this list is the most overdue thing
+   in the rulebook. No red/amber ramp: it would restate the ordering and force
+   an invented "stale after N days" threshold. "Never" is marked because it is
+   categorically different from a date, not a worse one. */
+.age { margin-left: auto; font-size: 0.78rem; color: var(--fs-text-secondary); font-variant-numeric: tabular-nums; }
+.age.unchecked { font-style: italic; color: var(--fs-text-tertiary); }
+
+.statement { margin: 0.35rem 0 0; font-size: 0.88rem; color: var(--fs-text-secondary); }
+
+.check { display: grid; grid-template-columns: auto 1fr; gap: 0.15rem var(--fs-space-3); margin: var(--fs-space-3) 0 0; }
+.check dt { font-size: 0.7rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--fs-text-tertiary); }
+.check dd { margin: 0; font-size: 0.82rem; color: var(--fs-text-primary); min-width: 0; }
+.check code {
+  font-family: var(--fs-font-mono);
+  background: var(--fs-surface-code-inline);
+  border-radius: var(--fs-radius-sm);
+  padding: 0.05rem 0.3rem;
+  overflow-wrap: anywhere;
+}
+
+.actions { display: flex; gap: var(--fs-space-2); margin-top: var(--fs-space-3); }
+.actions button {
+  cursor: pointer; font: inherit; font-size: 0.78rem;
+  background: var(--fs-surface-page); color: var(--fs-text-primary);
+  border: 1px solid var(--fs-border-color); border-radius: var(--fs-radius-md);
+  padding: 0.25rem 0.6rem;
+}
+.actions button:hover:not(:disabled) { background: var(--fs-surface-hover); }
+.actions button:disabled { opacity: var(--fs-disabled-opacity); cursor: default; }
+
+.footnote { margin: 0; max-width: 62ch; font-size: 0.78rem; color: var(--fs-text-tertiary); line-height: 1.45; }
+</style>
diff --git a/frontend/src/components/rules/RulebookListPane.vue b/frontend/src/components/rules/RulebookListPane.vue
index b808c3d..f76effe 100644
--- a/frontend/src/components/rules/RulebookListPane.vue
+++ b/frontend/src/components/rules/RulebookListPane.vue
@@ -3,8 +3,8 @@ import { ref } from "vue";
 import { useRulebooksStore } from "@/stores/rulebooks";
 import type { Rulebook } from "@/api/rulebooks";
 
-defineProps<{ rulebooks: Rulebook[]; selectedId: number | null }>();
-const emit = defineEmits<{ select: [id: number] }>();
+defineProps<{ rulebooks: Rulebook[]; selectedId: number | null; sweepActive: boolean }>();
+const emit = defineEmits<{ select: [id: number]; "select-sweep": [] }>();
 
 const store = useRulebooksStore();
 const isCreating = ref(false);
@@ -34,6 +34,18 @@ async function submitNew() {
         <span v-if="rb.always_on" class="always-on-badge" title="Loaded at session start">always on</span>
       </li>
     </ul>
+    <!-- Not a rulebook, and deliberately below them: a cross-cutting view over
+         every rule the operator owns. It lives here because this is where you
+         come to look at rules, and a rule that has gone false belongs to no
+         one rulebook. -->
+    <button
+      class="sweep-entry"
+      :class="{ active: sweepActive }"
+      @click="emit('select-sweep')"
+    >
+      Due for verification
+    </button>
+
     <div class="new-rulebook">
       <button v-if="!isCreating" @click="isCreating = true">+ New rulebook</button>
       <form v-else @submit.prevent="submitNew">
@@ -63,6 +75,15 @@ li:hover { background: var(--fs-surface-hover); }
   color: var(--fs-text-on-action);
   margin-left: auto;
 }
+.sweep-entry {
+  display: block; width: 100%; text-align: left;
+  margin-top: var(--fs-space-3);
+  padding: 0.5rem; border-radius: 6px;
+  background: none; border: 1px dashed var(--fs-border-color);
+  color: var(--fs-text-secondary); font: inherit; cursor: pointer;
+}
+.sweep-entry:hover { background: var(--fs-surface-hover); }
+.sweep-entry.active { background: var(--fs-accent-soft); color: var(--fs-text-primary); }
 .new-rulebook { margin-top: 1rem; }
 .new-rulebook input {
   width: 100%; margin-bottom: 0.5rem;
diff --git a/frontend/src/stores/rulebooks.ts b/frontend/src/stores/rulebooks.ts
index cfaa8ea..a02be56 100644
--- a/frontend/src/stores/rulebooks.ts
+++ b/frontend/src/stores/rulebooks.ts
@@ -9,6 +9,11 @@ export const useRulebooksStore = defineStore("rulebooks", () => {
   const topicsByRulebook = ref<Record<number, RulebookTopic[]>>({});
   const rulesByTopic = ref<Record<number, RuleHeader[]>>({});
   const currentRule = ref<Rule | null>(null);
+  const rulesDue = ref<api.RuleVerificationRow[]>([]);
+  // Kept so a verify re-reads the sweep with the SAME filters the operator is
+  // looking at — re-fetching unfiltered would silently widen the list under
+  // them at the moment they acted on it.
+  const lastSweepOpts = ref<{ olderThanDays?: number; tier?: api.RuleTier; neverOnly?: boolean }>({});
   const loading = ref(false);
 
   async function fetchRulebooks() {
@@ -111,6 +116,13 @@ export const useRulebooksStore = defineStore("rulebooks", () => {
       updated_at: rule.updated_at,
       when_to_apply: rule.when_to_apply || undefined,
       arose_from_id: rule.arose_from_id ?? undefined,
+      // Mirrors services.rulebooks.last_verified_label: present ONLY when the
+      // rule carries a check, and "never" rather than absent when it has one
+      // nobody has run. Computed here so a row just written looks identical to
+      // the same row re-fetched, instead of losing its chip until a reload.
+      last_verified: rule.verify_with
+        ? (rule.verified_at ? rule.verified_at.slice(0, 10) : "never")
+        : undefined,
     };
   }
 
@@ -148,6 +160,41 @@ export const useRulebooksStore = defineStore("rulebooks", () => {
     await fetchRule(refreshRuleId);
   }
 
+  /** The staleness sweep: rules asserting a fact, oldest verification first. */
+  async function fetchRulesDue(opts: {
+    olderThanDays?: number; tier?: api.RuleTier; neverOnly?: boolean;
+  } = {}) {
+    loading.value = true;
+    lastSweepOpts.value = opts;
+    try {
+      const data = await api.listRulesDueForVerification(opts);
+      rulesDue.value = data.rules;
+    } finally {
+      loading.value = false;
+    }
+  }
+
+  /**
+   * Record that a rule's check was RUN, and what it said.
+   *
+   * A pass re-sorts the row to the back of the sweep, so the list is re-read
+   * rather than patched: the whole point of this surface is an ORDER, and a
+   * locally-mutated row would sit in its old position claiming a new date.
+   * A failure writes nothing server-side and the row keeps its place — also
+   * correct, and also what a re-read shows.
+   */
+  async function verifyRule(id: number, stillTrue: boolean) {
+    const rule = await api.markRuleVerified(id, stillTrue);
+    if (currentRule.value?.id === id) currentRule.value = rule;
+    for (const tid of Object.keys(rulesByTopic.value)) {
+      const list = rulesByTopic.value[Number(tid)];
+      const idx = list.findIndex((r) => r.id === id);
+      if (idx >= 0) list[idx] = toHeader(rule);
+    }
+    if (rulesDue.value.length) await fetchRulesDue(lastSweepOpts.value);
+    return rule;
+  }
+
   async function deleteRule(id: number) {
     await api.deleteRule(id);
     if (currentRule.value?.id === id) currentRule.value = null;
@@ -157,10 +204,11 @@ export const useRulebooksStore = defineStore("rulebooks", () => {
   }
 
   return {
-    rulebooks, topicsByRulebook, rulesByTopic, currentRule, loading,
+    rulebooks, topicsByRulebook, rulesByTopic, currentRule, rulesDue, lastSweepOpts, loading,
     fetchRulebooks, fetchTopics, fetchRules, fetchRule,
     createRulebook, updateRulebook, toggleAlwaysOn, deleteRulebook,
     createTopic, updateTopic, deleteTopic,
     createRule, updateRule, deleteRule, relateRules, unrelateRules,
+    fetchRulesDue, verifyRule,
   };
 });
diff --git a/frontend/src/types/note.ts b/frontend/src/types/note.ts
index 64105e4..c11a9d3 100644
--- a/frontend/src/types/note.ts
+++ b/frontend/src/types/note.ts
@@ -2,7 +2,16 @@ import type { System } from "@/api/systems";
 
 export type TaskStatus = "todo" | "in_progress" | "done" | "cancelled";
 export type TaskPriority = "none" | "low" | "medium" | "high";
-export type TaskKind = "work" | "plan" | "issue";
+/**
+ * What KIND of work a task is, not how it is going.
+ *   work  — ships a change (default)
+ *   issue — corrective; something was broken
+ *   spike — time-boxed, output is knowledge; it succeeds by producing an
+ *           answer and nothing ships at the end of it
+ *   plan  — retired (plans are milestones); kept so historical plan-tasks
+ *           still render their kind
+ */
+export type TaskKind = "work" | "plan" | "issue" | "spike";
 export type NoteType = "note" | "process" | "snippet";
 
 export interface Note {
diff --git a/frontend/src/views/RulesView.vue b/frontend/src/views/RulesView.vue
index 1236267..c201e2e 100644
--- a/frontend/src/views/RulesView.vue
+++ b/frontend/src/views/RulesView.vue
@@ -6,6 +6,7 @@ import RulebookListPane from "@/components/rules/RulebookListPane.vue";
 import RulebookDetailPane from "@/components/rules/RulebookDetailPane.vue";
 import RuleListPane from "@/components/rules/RuleListPane.vue";
 import RuleEditorSlideOver from "@/components/rules/RuleEditorSlideOver.vue";
+import RuleSweepPane from "@/components/rules/RuleSweepPane.vue";
 
 const store = useRulebooksStore();
 const route = useRoute();
@@ -15,6 +16,7 @@ const selectedRulebookId = ref<number | null>(null);
 const selectedTopicId = ref<number | null>(null);
 const editingRuleId = ref<number | null>(null);
 const creatingRuleForTopic = ref<number | null>(null);
+const sweepActive = ref(false);
 
 function syncFromRoute() {
   const rb = route.query.rb ? Number(route.query.rb) : null;
@@ -23,9 +25,20 @@ function syncFromRoute() {
   selectedRulebookId.value = rb;
   selectedTopicId.value = topic;
   editingRuleId.value = rule;
+  sweepActive.value = route.query.view === "due";
+}
+
+function selectSweep() {
+  sweepActive.value = true;
+  // Keeps ?rule=… so the editor survives the mode switch, and drops the
+  // rulebook/topic selection the sweep does not use.
+  const { rb, topic, ...rest } = route.query;
+  void rb; void topic;
+  router.replace({ query: { ...rest, view: "due" } });
 }
 
 function selectRulebook(id: number) {
+  sweepActive.value = false;
   selectedRulebookId.value = id;
   selectedTopicId.value = null;
   router.replace({ query: { rb: String(id) } });
@@ -70,10 +83,13 @@ watch(() => route.query, syncFromRoute);
     <RulebookListPane
       :rulebooks="store.rulebooks"
       :selected-id="selectedRulebookId"
+      :sweep-active="sweepActive"
       @select="selectRulebook"
+      @select-sweep="selectSweep"
     />
+    <RuleSweepPane v-if="sweepActive" class="sweep-span" @open-rule="openRule" />
     <RulebookDetailPane
-      v-if="selectedRulebookId !== null"
+      v-else-if="selectedRulebookId !== null"
       :rulebook-id="selectedRulebookId"
       :topics="store.topicsByRulebook[selectedRulebookId] || []"
       :selected-topic-id="selectedTopicId"
@@ -83,13 +99,13 @@ watch(() => route.query, syncFromRoute);
       <p>Select a rulebook to view its topics.</p>
     </div>
     <RuleListPane
-      v-if="selectedTopicId !== null"
+      v-if="!sweepActive && selectedTopicId !== null"
       :topic-id="selectedTopicId"
       :rules="store.rulesByTopic[selectedTopicId] || []"
       @open-rule="openRule"
       @create-rule="startCreatingRule"
     />
-    <div v-else class="pane empty">
+    <div v-else-if="!sweepActive" class="pane empty">
       <p>Select a topic to view its rules.</p>
     </div>
     <RuleEditorSlideOver
@@ -109,6 +125,9 @@ watch(() => route.query, syncFromRoute);
   gap: 1px;
   background: var(--fs-border-color);
 }
+/* The sweep is cross-cutting, so it takes the width the rulebook + topic
+   panes would have used rather than being squeezed into one column. */
+.sweep-span { grid-column: 2 / -1; }
 .pane.empty {
   background: var(--fs-surface-hover);
   padding: 1rem;
diff --git a/frontend/src/views/TaskEditorView.vue b/frontend/src/views/TaskEditorView.vue
index f19115f..4212ca5 100644
--- a/frontend/src/views/TaskEditorView.vue
+++ b/frontend/src/views/TaskEditorView.vue
@@ -578,6 +578,7 @@ useEditorGuards(dirty, save);
             <select v-model="kind" @change="markDirty" class="sb-select">
               <option value="work">Work</option>
               <option value="issue">Issue</option>
+              <option value="spike">Spike</option>
               <!-- 'plan' is retired (plans are milestones via start_planning);
                    offered only so legacy plan-tasks display their kind. -->
               <option v-if="kind === 'plan'" value="plan">Plan (legacy)</option>
diff --git a/src/scribe/mcp/tools/rulebooks.py b/src/scribe/mcp/tools/rulebooks.py
index 6d3c094..ee5da8e 100644
--- a/src/scribe/mcp/tools/rulebooks.py
+++ b/src/scribe/mcp/tools/rulebooks.py
@@ -246,6 +246,14 @@ async def list_always_on_rules(project_id: int = 0) -> dict:
     Pair with get_project(id).applicable_rules when working on a specific
     project to also load that project's subscription-derived rules.
 
+    A rule carrying `last_verified` asserts a FACT about something outside the
+    operator's control — a runner's shell, a tool's existence, a setting
+    somewhere. It is still binding; the field says how long ago anyone
+    confirmed it, and "never" means nobody has. Follow the rule, and if you
+    are already standing where the check could be made, make it: get_rule
+    gives you its `verify_with`. Most rules have no such field, which means
+    they are decisions and there is nothing to check.
+
     Args:
         project_id: 0 (default) = the user-wide set. Inside a project, pass
             its id: an always-on rulebook the project EXCLUDED at inception
@@ -276,7 +284,8 @@ async def create_rule(
     topic_id: int, title: str, statement: str, when_to_apply: str = "",
     why: str = "", how_to_apply: str = "", order_index: int = 0,
     tier: str = "always_on", system_ids: list[int] | None = None,
-    arose_from_id: int = 0, force: bool = False,
+    arose_from_id: int = 0, verify_with: str = "", expires_when: str = "",
+    force: bool = False,
 ) -> dict:
     """Create a new rule in a rulebook (a SHARED rule — keep it general).
 
@@ -288,6 +297,13 @@ async def create_rule(
     rulebook+topic ceremony). If it's a standard a CATEGORY of projects shares,
     put it in a themed subscribed rulebook, not the always-on one.
 
+    Write it general WITHOUT hedging for the exceptions. A project that needs
+    to strengthen, narrow or replace this rule writes its own and links it
+    with relate_rules(kind="overrides"), and one that adds local specifics
+    uses "elaborates" — so the general form does not have to anticipate every
+    project it will ever reach. A rulebook rule padded with "unless…" clauses
+    for two projects is two project rules that were never written.
+
     Before writing a rule at all, check whether another entity already models
     the thing. A rule is prose an agent must remember and apply; the others
     are structure a tool can resolve, render and check. Visual standards are a
@@ -314,6 +330,15 @@ async def create_rule(
             optional: it decides the tier below, it is how the rule is found
             when it matters, and a rule nobody can place is a rule nobody
             applies.
+            This field is also the rule's RETRIEVAL SURFACE — it and the
+            statement are what a search is matched against, so it should
+            carry the SYMPTOM, not just the situation: the words someone
+            would actually type while stuck. Measured (note 3078): a rule
+            whose trigger named only its situation did not surface at all
+            for the problem it solves; adding the symptom to the same field
+            brought it back as the top hit. Where a rule prevents a specific
+            failure, put that failure's vocabulary here — the error text,
+            the wrong behaviour, the dead end.
         tier: "always_on" (default) or "conditional".
             The test: can you name the trigger WITHOUT naming a system, an
             artifact type or a moment? If the honest answer is "whenever you
@@ -328,6 +353,23 @@ async def create_rule(
             cannot be followed and does not survive a rewording.
         why: Optional rationale — the reason the rule exists.
         how_to_apply: Optional operationalization — when / where it kicks in.
+        verify_with: How to CHECK this rule is still true. Set it only when
+            the rule asserts a fact about something outside your control — a
+            runner's shell, a bot's config, whether a tool exists. Those go
+            false silently, with nobody present. Give a command, a path, a
+            URL or a query; something runnable beats prose, because prose
+            has to be re-interpreted by whoever finds it.
+            LEAVE IT EMPTY for a rule that is a DECISION — a preference, a
+            standard, a way of working. A decision has no truth value: it
+            changes when you change it, and you know that you did. An empty
+            verify_with is not a gap, it is the marker for "there is nothing
+            to go and check," and the whole signal is worthless the moment
+            it is filled in out of tidiness.
+        expires_when: The STATE under which this rule stops being true —
+            "when the runner can be given a bash shell", "when the dashboard
+            approval setting is turned off". Deliberately not a date: a
+            constraint expires when the ground under it moves, not on a
+            schedule. Pairs with verify_with; both empty is the normal case.
         order_index: Display order within the topic (default 0).
         force: Bypass the near-duplicate gate. By default, a title-identical rule
             already in this topic BLOCKS creation and returns its id so you update
@@ -343,6 +385,7 @@ async def create_rule(
         title=title, statement=statement, when_to_apply=when_to_apply,
         tier=tier, arose_from_id=arose_from_id,
         why=why, how_to_apply=how_to_apply, order_index=order_index,
+        verify_with=verify_with, expires_when=expires_when,
     )
     return await rulebooks_svc.rule_detail(uid, rule, system_ids)
 
@@ -351,7 +394,8 @@ async def create_project_rule(
     project_id: int, statement: str, title: str = "", when_to_apply: str = "",
     why: str = "", how_to_apply: str = "", order_index: int = 0,
     tier: str = "always_on", system_ids: list[int] | None = None,
-    arose_from_id: int = 0, force: bool = False,
+    arose_from_id: int = 0, verify_with: str = "", expires_when: str = "",
+    force: bool = False,
 ) -> dict:
     """Create a rule scoped to a single project (no rulebook needed).
 
@@ -375,14 +419,45 @@ async def create_project_rule(
         title: Short imperative title. If empty, derived from the first ~50
             characters of statement.
         when_to_apply: WHEN this rule fires — the trigger, not the
-            instruction. See create_rule; it decides the tier and it is how
-            the rule is found at the moment it matters.
-        tier: "always_on" (default) or "conditional" — see create_rule.
+            instruction, and the rule's retrieval surface: name the SYMPTOM,
+            the words someone would type while stuck. See create_rule for the
+            full argument. It informs the tier below rather than deciding it,
+            since a project rule's tier turns on area-scope, not on whether
+            the trigger can be named.
+        tier: "always_on" (default) or "conditional". The SAME two values as
+            create_rule, judged against a different cost — do not import that
+            tool's test wholesale. There, always_on means every session in
+            every project, so the bar is high: the trigger must be nameless
+            ("whenever you are working"). Here the rule is already scoped to
+            one project by construction, so always_on costs only that
+            project's sessions and the bar is correspondingly lower. A
+            project rule that names something specific is still ordinarily
+            always_on — being specific is what project rules are FOR.
+            Reach for conditional when the rule is about one AREA of a large
+            project — a CI quirk, a migration gotcha, one subsystem's
+            convention — so it arrives with that area instead of resident in
+            every session. The failure to avoid is local: forty always-on
+            rules on one project reproduces, inside that project, exactly the
+            preload bloat that made every rule compete for the same budget.
         system_ids: Ids from list_canonical_systems — the global AREAS this
-            rule is about.
-        arose_from_id: The note or task that CAUSED this rule.
+            rule is about. Worth setting even on a project rule: it is what
+            lets a conditional one surface when the project is working in
+            that area.
+        arose_from_id: The note or task that CAUSED this rule. Reach for it
+            harder here than on a rulebook rule — a project rule usually
+            comes from one traceable incident in this repo, where a family
+            rule is more often a standing preference with no single origin.
+            The link is what lets a later reader judge whether the incident
+            still describes the project.
         why: Optional rationale — the reason the rule exists.
         how_to_apply: Optional operationalization — when / where it kicks in.
+        verify_with: How to check this rule is still true — see create_rule.
+            Set it when the rule asserts a fact about someone else's software;
+            leave it empty when the rule is a decision. Project rules are the
+            likelier home for a real check: they name this project's files,
+            paths and quirks, which is exactly the kind of claim that rots.
+        expires_when: The state under which the rule stops being true — see
+            create_rule. A state, not a date.
         order_index: Display order within the project's rule list (default 0).
         force: Bypass the near-duplicate gate. By default, a title-identical rule
             already on this project BLOCKS creation and returns its id so you
@@ -399,6 +474,7 @@ async def create_project_rule(
         title=derived_title, statement=statement, when_to_apply=when_to_apply,
         tier=tier, arose_from_id=arose_from_id,
         why=why, how_to_apply=how_to_apply, order_index=order_index,
+        verify_with=verify_with, expires_when=expires_when,
     )
     return await rulebooks_svc.rule_detail(uid, rule, system_ids)
 
@@ -407,12 +483,33 @@ async def update_rule(
     rule_id: int, title: str = "", statement: str = "", when_to_apply: str = "",
     why: str = "", how_to_apply: str = "", order_index: int = -1,
     tier: str = "", system_ids: list[int] | None = None, arose_from_id: int = 0,
+    verify_with: str = "", expires_when: str = "",
+    clear_fields: list[str] | None = None,
 ) -> dict:
     """Update a rule. Empty strings / order_index=-1 leave fields unchanged.
 
     Adding `when_to_apply` and a `tier` to an existing rule is the ordinary way
     a rule stops being preloaded into every session and starts arriving when it
     is relevant. `system_ids` REPLACES the rule's areas (pass [] to clear).
+
+    TO EMPTY A FIELD, NAME IT: clear_fields=["verify_with"]. Passing "" cannot
+    do it — "" means "leave this alone" here, which is what lets you update
+    two fields without wiping the other six. Clearable: why, how_to_apply,
+    when_to_apply, verify_with, expires_when, arose_from_id. Clearing and
+    setting the same field in one call clears it first, so the new value wins.
+
+    Editing `verify_with` DROPS the rule's verification stamp. The stamp
+    certifies a check, not a rule; once the check is reworded the old stamp
+    vouches for something that no longer exists, so the rule re-enters the
+    staleness sweep as never-verified.
+
+    Args:
+        verify_with: How to check the rule is still true — set it when the
+            rule asserts a fact about someone else's software, leave it empty
+            when the rule is a decision. See create_rule.
+        expires_when: The state under which the rule stops being true. A
+            state, not a date. See create_rule.
+        clear_fields: Names of fields to empty, as above.
     """
     uid = current_user_id()
     fields: dict = {}
@@ -430,9 +527,15 @@ async def update_rule(
         fields["why"] = why
     if how_to_apply:
         fields["how_to_apply"] = how_to_apply
+    if verify_with:
+        fields["verify_with"] = verify_with
+    if expires_when:
+        fields["expires_when"] = expires_when
     if order_index >= 0:
         fields["order_index"] = order_index
-    rule = await rulebooks_svc.update_rule(rule_id, uid, **fields)
+    rule = await rulebooks_svc.update_rule(
+        rule_id, uid, clear=clear_fields or (), **fields,
+    )
     if rule is None:
         raise ValueError(f"rule {rule_id} not found")
     return await rulebooks_svc.rule_detail(uid, rule, system_ids)
@@ -619,6 +722,97 @@ async def unrelate_rules(relation_id: int) -> dict:
         raise ValueError(f"relation {relation_id} not found")
     return {"deleted": relation_id}
 
+# ── The staleness sweep (milestone 312) ────────────────────────────────
+
+async def rules_due_for_verification(
+    older_than_days: int = 0, tier: str = "", never_only: bool = False,
+) -> dict:
+    """Which standing rules assert a FACT that nobody has confirmed lately.
+
+    A rulebook holds two kinds of thing. Most rules are DECISIONS — how the
+    operator wants to work. They have no truth value and cannot rot. A few
+    assert a fact about someone else's software: what a CI runner does, which
+    tools exist, what a setting is currently set to. Those go false silently,
+    with nobody present, and they keep being handed to every session as
+    binding instructions long after they stopped being true.
+
+    This lists the second kind, oldest verification first, never-checked at
+    the top. Each row carries the rule's `verify_with` in full — you are
+    about to go and run it — plus `expires_when`, and `days_since_verified`.
+
+    Reach for it when you are curating the rulebook, when a rule's advice
+    just contradicted what you observed, or periodically. Then, for each row:
+    run the check, and call mark_rule_verified with what you found.
+
+    Rules with no `verify_with` never appear here. That is correct: they are
+    decisions, and there is nothing to go and check. Do not "fix" their
+    absence by giving them checks — the list is only worth reading while
+    everything on it genuinely can go false.
+
+    Args:
+        older_than_days: only rules last verified longer ago than this.
+            Never-checked rules always qualify. 0 = no age filter.
+        tier: "always_on" or "conditional" to narrow. An always-on constraint
+            that has gone false is the expensive kind — it is preloaded into
+            every session, so a wrong one is wrong everywhere at once.
+        never_only: only rules nobody has ever verified.
+
+    NOT filterable by project, deliberately: a project reaches rules through
+    project scope, subscriptions, always-on rulebooks and exclusions, and a
+    filter that missed one of those paths would UNDER-report — which is the
+    exact failure this whole surface exists to prevent. Read the whole list.
+    """
+    uid = current_user_id()
+    rules = await rulebooks_svc.rules_due_for_verification(
+        uid, older_than_days=older_than_days, tier=tier, never_only=never_only,
+    )
+    return {
+        "rules": [rulebooks_svc.verification_row(r) for r in rules],
+        "total": len(rules),
+    }
+
+
+async def mark_rule_verified(rule_id: int, still_true: bool = True) -> dict:
+    """Record that you ran a rule's check — and what it said.
+
+    Call this AFTER actually running the rule's `verify_with`, never on the
+    strength of the rule sounding plausible. A stamp nobody earned is worse
+    than no stamp: it moves the rule to the bottom of the sweep and buys it
+    another long silence.
+
+    `still_true=False` writes NOTHING. A rule whose check failed is not in a
+    special state to be recorded — it is WRONG, and the only honest next
+    moves are to correct it, retire it, or find out why. So it stays at the
+    top of the sweep until someone deals with it, and the response tells you
+    what the rule said would end it.
+
+    Args:
+        rule_id: the rule whose check you ran.
+        still_true: True if the check passed. False if the fact it asserts is
+            no longer true — say so, that is the outcome worth having.
+    """
+    uid = current_user_id()
+    rule = await rulebooks_svc.mark_rule_verified(rule_id, uid, still_true)
+    if rule is None:
+        raise ValueError(
+            f"rule {rule_id} not found, or carries no verify_with "
+            f"(nothing to verify is not the same as verified)"
+        )
+    data = await rulebooks_svc.rule_detail(uid, rule)
+    if still_true:
+        data["verified"] = True
+        return data
+    data["verified"] = False
+    data["next"] = (
+        "This rule is no longer true and is still binding on every session "
+        "that loads it. Correct it with update_rule, retire it with "
+        "delete_rule, or open a task to work out what replaced it. Its "
+        "verified_at is deliberately untouched, so it stays at the top of "
+        "rules_due_for_verification until one of those happens."
+    )
+    return data
+
+
 def register(mcp) -> None:
     for fn in (
         list_rulebooks, get_rulebook, create_rulebook, update_rulebook, delete_rulebook,
@@ -630,5 +824,6 @@ def register(mcp) -> None:
         suppress_rule_for_project, unsuppress_rule_for_project,
         suppress_topic_for_project, unsuppress_topic_for_project,
         exclude_always_on_rulebook, include_always_on_rulebook,
+        rules_due_for_verification, mark_rule_verified,
     ):
         mcp.tool(name=fn.__name__)(fn)
diff --git a/src/scribe/mcp/tools/search.py b/src/scribe/mcp/tools/search.py
index e7eb1c4..c6db75d 100644
--- a/src/scribe/mcp/tools/search.py
+++ b/src/scribe/mcp/tools/search.py
@@ -14,6 +14,7 @@ from scribe.services.access import owner_names_for
 from scribe.services.embeddings import (
     DEFAULT_SIMILARITY_THRESHOLD, semantic_search_notes, semantic_search_rules,
 )
+from scribe.services import rulebooks as rulebooks_svc
 from scribe.services.retrieval_telemetry import record_retrieval, retrieval_summary
 
 
@@ -23,7 +24,10 @@ async def _search_rules(uid: int, q: str, limit: int) -> dict:
     A rule hit carries `why` and `how_to_apply`: they are the operational half
     of a rule and the session-start payload never includes them, so a caller
     who went looking should get the whole thing rather than a summary they then
-    have to re-fetch.
+    have to re-fetch. It also carries the rule's check (`verify_with`,
+    `expires_when`, `last_verified`) when it has one — a search hit is exactly
+    the moment someone is about to act on a rule, and "this asserts a fact
+    nobody has confirmed" is part of what the rule says.
 
     Rules are not project-scoped the way notes are (a family rule belongs to no
     project), so `project_id` and `system_id` do not apply here.
@@ -39,6 +43,14 @@ async def _search_rules(uid: int, q: str, limit: int) -> dict:
                 "tier": rule.tier,
                 "why": rule.why or "",
                 "how_to_apply": rule.how_to_apply or "",
+                "verify_with": rule.verify_with or "",
+                "expires_when": rule.expires_when or "",
+                # Only on a rule that carries a check; its absence means the
+                # rule is a decision, not that nobody has looked.
+                **(
+                    {"last_verified": rulebooks_svc.last_verified_label(rule)}
+                    if rule.verify_with else {}
+                ),
                 "topic_id": rule.topic_id,
                 "project_id": rule.project_id,
                 "similarity": float(score),
diff --git a/src/scribe/mcp/tools/systems.py b/src/scribe/mcp/tools/systems.py
index 79ca91c..df0050e 100644
--- a/src/scribe/mcp/tools/systems.py
+++ b/src/scribe/mcp/tools/systems.py
@@ -336,7 +336,8 @@ async def list_system_records(
     slice, search(system_id=...) filters semantic search to this association.
 
     Args:
-        kind: filter by task_kind — 'issue', 'work', or 'plan'. Omit for all.
+        kind: filter by task_kind — 'issue', 'work', 'spike' (or the retired
+            'plan'). Omit for all.
         open_only: limit to tasks not done/cancelled (e.g. open issues only).
     """
     uid = current_user_id()
diff --git a/src/scribe/mcp/tools/tasks.py b/src/scribe/mcp/tools/tasks.py
index 1c30055..1c81988 100644
--- a/src/scribe/mcp/tools/tasks.py
+++ b/src/scribe/mcp/tools/tasks.py
@@ -46,7 +46,8 @@ async def list_tasks(
             whenever a project is in scope so you list that project's tasks, not
             every project's. 0 = no filter (all projects — use only for a
             deliberate cross-project view).
-        kind: Filter by task kind — 'work', 'plan', or 'issue'. Omit (empty) for all kinds.
+        kind: Filter by task kind — 'work', 'issue', 'spike' (or the retired
+            'plan'). Omit (empty) for all kinds.
 
     Results are ordered by last-updated descending.
     """
@@ -138,14 +139,24 @@ async def create_task(
         milestone_id: Place within a project milestone (0 = no milestone).
         parent_id: Make this a sub-task of another task (0 = top-level).
         tags: List of plain-string tags without # prefix.
-        kind: 'work' (default) or 'issue'. An issue is corrective work — a
-            problem you fixed or are fixing; record symptom → root cause → fix
-            in the body. (Plans are milestones now — call start_planning to begin
-            a plan; 'plan' is not a valid kind here.)
+        kind: 'work' (default), 'issue', or 'spike'.
+            An ISSUE is corrective work — a problem you fixed or are fixing;
+            record symptom → root cause → fix in the body.
+            A SPIKE is time-boxed and its output is KNOWLEDGE rather than a
+            change: "find out whether the runner can be given a bash shell",
+            "work out why the index is not used". It succeeds by producing an
+            answer, so nothing ships at the end of it — which is why filing
+            one as `work` makes a finished investigation look like an
+            abandoned change. Reach for it when the honest deliverable is a
+            finding, and say in the body what would close the box: a time, or
+            the question being answered well enough to act on.
+            (Plans are milestones now — call start_planning to begin a plan;
+            'plan' is not a valid kind here.)
         system_ids: Ids of the project's Systems (reusable subsystem/area
             objects; see list_systems / create_system) to associate this task with.
-        arose_from_id: For an issue, the id of the task/feature it arose from
-            (provenance). 0 = none.
+        arose_from_id: For an issue, the id of the task/feature it arose from;
+            for a spike, the record that raised the question — including a
+            standing rule whose check just failed. 0 = none.
         force: Bypass the near-duplicate gate. By default, if a title- or
             meaning-similar task already exists in the same project, creation is
             BLOCKED and the existing task's id is returned so you update it
diff --git a/src/scribe/models/note.py b/src/scribe/models/note.py
index f09b16e..762883b 100644
--- a/src/scribe/models/note.py
+++ b/src/scribe/models/note.py
@@ -61,10 +61,16 @@ class Note(Base, TimestampMixin, SoftDeleteMixin):
     # Note type — 'note' (default) or 'process' (a stored process). Task-ness is
     # tracked by `status`, not here. (person/place/list entity types removed 2026-07.)
     note_type: Mapped[str] = mapped_column(Text, default="note", server_default="note")
-    # Task sub-kind — 'work' (default), 'plan', or 'issue' (corrective work).
+    # Task sub-kind — what KIND of work this is, not how it is going:
+    #   work   (default) — ships a change
+    #   issue  — corrective; something was broken (0065)
+    #   spike  — time-boxed, and its output is KNOWLEDGE rather than a change;
+    #            it succeeds by producing an answer, and nothing ships (0091)
+    #   plan   — retired since 0066 (plans are milestones), kept in the CHECK
+    #            so historical plan-tasks stay writable
     # Only meaningful when the note is a task (status is not None); ordinary
     # notes keep the 'work' default and ignore it. Orthogonal to note_type
-    # (which is the note/entity axis).
+    # (which is the note/entity axis). CHECK notes_task_kind_check (rule 36).
     task_kind: Mapped[str] = mapped_column(Text, default="work", server_default="work")
     # Queryable structured fields for typed records — currently snippets, whose
     # name/language/signature/locations live here so they can be INDEXED. The
diff --git a/src/scribe/models/rulebook.py b/src/scribe/models/rulebook.py
index d05da94..ac581cb 100644
--- a/src/scribe/models/rulebook.py
+++ b/src/scribe/models/rulebook.py
@@ -107,6 +107,26 @@ class Rule(Base, TimestampMixin, SoftDeleteMixin):
     tier: Mapped[str] = mapped_column(Text, default="always_on", server_default="always_on")
     why: Mapped[str | None] = mapped_column(Text, nullable=True)
     how_to_apply: Mapped[str | None] = mapped_column(Text, nullable=True)
+    # The three fields that tell a CONSTRAINT apart from a NORM (milestone
+    # 312). A norm is a decision — no truth value, changes only when its
+    # author changes it. A constraint asserts a fact about someone else's
+    # software, and goes false with nobody watching: every stale rule the
+    # 307 audit found was one, and no norm had rotted.
+    #
+    # `verify_with` is how to check the rule is still true; `expires_when` is
+    # the STATE that ends it, deliberately not a date — constraints expire
+    # when the ground moves, not on a schedule. `verified_at` NULL means
+    # never checked, and sorts FIRST in the sweep: unexamined outranks
+    # examined-long-ago.
+    #
+    # Most rules should leave all three empty. A null `verify_with` is not a
+    # gap — it is the marker for "this is a decision, there is nothing to go
+    # and check," and the signal is only worth reading while that stays true.
+    verify_with: Mapped[str | None] = mapped_column(Text, nullable=True)
+    expires_when: Mapped[str | None] = mapped_column(Text, nullable=True)
+    verified_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True
+    )
     # The record that caused this rule — the edge notes and tasks already
     # have. Rule 46's `why` names note 2813 in prose; this is that link as a
     # field, so it survives a rewording of the paragraph.
@@ -126,6 +146,9 @@ class Rule(Base, TimestampMixin, SoftDeleteMixin):
             "tier": self.tier,
             "why": self.why or "",
             "how_to_apply": self.how_to_apply or "",
+            "verify_with": self.verify_with or "",
+            "expires_when": self.expires_when or "",
+            "verified_at": iso(self.verified_at),
             "arose_from_id": self.arose_from_id,
             "order_index": self.order_index,
             "created_at": iso(self.created_at),
diff --git a/src/scribe/routes/rulebooks.py b/src/scribe/routes/rulebooks.py
index 08d0d9e..2acc4bb 100644
--- a/src/scribe/routes/rulebooks.py
+++ b/src/scribe/routes/rulebooks.py
@@ -165,6 +165,8 @@ async def create_rule(topic_id: int):
             when_to_apply=data.get("when_to_apply", ""),
             tier=data.get("tier", "always_on"),
             arose_from_id=data.get("arose_from_id", 0) or 0,
+            verify_with=data.get("verify_with", ""),
+            expires_when=data.get("expires_when", ""),
         )
     except ValueError as exc:
         return jsonify({"error": str(exc)}), 404
@@ -191,8 +193,13 @@ async def update_rule(rule_id: int):
     fields = {
         k: v for k, v in data.items()
         if k in ("title", "statement", "why", "how_to_apply", "order_index",
-                 "when_to_apply", "tier", "arose_from_id")
+                 "when_to_apply", "tier", "arose_from_id",
+                 "verify_with", "expires_when")
     }
+    # No clear_fields here: a form sends "" for an emptied input, and the
+    # service normalises "" to NULL for every nullable text column. The MCP
+    # door needs the explicit list only because "" already means "unchanged"
+    # there — two idioms, one outcome.
     rule = await rulebooks_svc.update_rule(rule_id, uid, **fields)
     if rule is None:
         return jsonify({"error": "rule not found"}), 404
@@ -375,9 +382,64 @@ async def create_project_rule(project_id: int):
             when_to_apply=data.get("when_to_apply", ""),
             tier=data.get("tier", "always_on"),
             arose_from_id=data.get("arose_from_id", 0) or 0,
+            verify_with=data.get("verify_with", ""),
+            expires_when=data.get("expires_when", ""),
         )
     except ValueError as exc:
         return jsonify({"error": str(exc)}), 404
     return jsonify(await rulebooks_svc.rule_detail(
         get_current_user_id(), rule, data.get("system_ids"),
     )), 201
+
+
+# ── The staleness sweep (milestone 312) ────────────────────────────────
+
+@rulebooks_bp.get("/rules-due-for-verification")
+@login_required
+async def rules_due_for_verification():
+    """Rules that carry a check, oldest verification first, never-checked top.
+
+    Query params: older_than_days, tier, never_only. A rule with no
+    `verify_with` never appears — it is a decision, not a fact.
+    """
+    uid = get_current_user_id()
+    args = request.args
+    try:
+        older = int(args.get("older_than_days", 0) or 0)
+    except ValueError:
+        return jsonify({"error": "older_than_days must be an integer"}), 400
+    try:
+        rules = await rulebooks_svc.rules_due_for_verification(
+            uid,
+            older_than_days=older,
+            tier=args.get("tier", ""),
+            never_only=args.get("never_only", "").lower() in ("1", "true", "yes"),
+        )
+    except ValueError as exc:
+        # An unrecognised tier is a 400, not a silently narrowed result set:
+        # a filter that quietly answers a different question is the failure
+        # this whole surface exists to catch.
+        return jsonify({"error": str(exc)}), 400
+    return jsonify({
+        "rules": [rulebooks_svc.verification_row(r) for r in rules],
+        "total": len(rules),
+    })
+
+
+@rulebooks_bp.post("/rules/<int:rule_id>/verify")
+@login_required
+async def mark_rule_verified(rule_id: int):
+    """Record that the rule's check was run. Body: {"still_true": bool}.
+
+    `still_true: false` writes nothing — a rule whose check failed is wrong,
+    not in a recordable state — so it stays at the top of the sweep.
+    """
+    data = await request.get_json() or {}
+    uid = get_current_user_id()
+    still_true = data.get("still_true", True)
+    rule = await rulebooks_svc.mark_rule_verified(rule_id, uid, bool(still_true))
+    if rule is None:
+        return jsonify({"error": "rule not found, or carries no verify_with"}), 404
+    payload = await rulebooks_svc.rule_detail(uid, rule)
+    payload["verified"] = bool(still_true)
+    return jsonify(payload)
diff --git a/src/scribe/services/backup.py b/src/scribe/services/backup.py
index 7140da1..dd23826 100644
--- a/src/scribe/services/backup.py
+++ b/src/scribe/services/backup.py
@@ -112,6 +112,18 @@ def _dt(val: str | None) -> datetime:
     return datetime.fromisoformat(val) if val else datetime.now(timezone.utc)
 
 
+def _dt_or_none(val: str | None) -> datetime | None:
+    """Like _dt, but keeps an absent timestamp absent.
+
+    _dt substitutes now() because created_at/updated_at must not be null.
+    For a nullable column that MEANS something by being empty, that default
+    is a lie: a rule nobody ever verified would restore looking verified at
+    the moment of the restore, and drop straight to the bottom of the sweep
+    it should have topped.
+    """
+    return datetime.fromisoformat(val) if val else None
+
+
 def _d(val: str | None) -> date | None:
     return date.fromisoformat(val) if val else None
 
@@ -385,6 +397,8 @@ def _rule_rows(rows) -> list[dict]:
             "title": r.title, "statement": r.statement, "why": r.why,
             "how_to_apply": r.how_to_apply, "order_index": r.order_index,
             "when_to_apply": r.when_to_apply, "tier": r.tier,
+            "verify_with": r.verify_with, "expires_when": r.expires_when,
+            "verified_at": r.verified_at.isoformat() if r.verified_at else None,
             "arose_from_id": r.arose_from_id,
             "created_at": r.created_at.isoformat(),
             "updated_at": r.updated_at.isoformat(),
@@ -1007,6 +1021,19 @@ async def _restore_v2(data: dict) -> dict:
                 # is the pre-0088 behaviour, so an old backup restores rules
                 # that bind exactly as they did when it was taken.
                 tier=r_data.get("tier") or "always_on",
+                verify_with=r_data.get("verify_with") or None,
+                expires_when=r_data.get("expires_when") or None,
+                # Restored as-is, NOT reset to null. `verified_at` records
+                # when someone last ran the check; a restore does not make
+                # that untrue, and clearing it would put every constraint at
+                # the top of the sweep with nothing having actually changed.
+                verified_at=_dt_or_none(r_data.get("verified_at")),
+                # Remapped through note_id_map like every other note edge.
+                # Exported since 0088 but dropped on the way back in until
+                # milestone 312 — a restore silently lost every rule's
+                # provenance link. SET NULL semantics apply here too: a
+                # source note that didn't restore leaves the rule intact.
+                arose_from_id=note_id_map.get(r_data.get("arose_from_id") or 0),
                 order_index=r_data.get("order_index", 0),
                 created_at=_dt(r_data.get("created_at")),
                 updated_at=_dt(r_data.get("updated_at")),
diff --git a/src/scribe/services/rulebooks.py b/src/scribe/services/rulebooks.py
index aece902..536754e 100644
--- a/src/scribe/services/rulebooks.py
+++ b/src/scribe/services/rulebooks.py
@@ -8,9 +8,10 @@ depending on the caller's needs (mirroring services/events.py pattern).
 from __future__ import annotations
 
 import logging
+from collections.abc import Iterable
 from typing import Optional
 
-from sqlalchemy import delete as sql_delete, insert, or_, select
+from sqlalchemy import and_, delete as sql_delete, insert, or_, select
 
 from scribe.models import async_session
 from scribe.models.system import System
@@ -288,6 +289,17 @@ TIERS = ("always_on", "conditional")
 RELATION_KINDS = ("co_surfaces", "overrides", "elaborates")
 
 
+# The rule columns that are nullable, and therefore the ones where EMPTY has
+# to mean empty. A write that stores "" leaves a column that is not NULL and
+# not content — `verify_with IS NOT NULL` would then be true for a rule with
+# no check, and the staleness sweep would list rules it should never see.
+# Normalising here, at the one service seam, is what makes "unset" a single
+# state instead of two that read alike through to_dict's `or ""`.
+NULLABLE_RULE_TEXT = (
+    "why", "how_to_apply", "when_to_apply", "verify_with", "expires_when",
+)
+
+
 def _valid_tier(tier: str) -> str:
     """An unrecognised tier falls back to always_on — the SAFE direction.
 
@@ -299,6 +311,21 @@ def _valid_tier(tier: str) -> str:
     return tier if tier in TIERS else "always_on"
 
 
+def last_verified_label(rule: Rule) -> str | None:
+    """How long ago the rule's check passed — None when it carries no check.
+
+    One helper because two surfaces need the same answer and the brief-dict
+    lesson in rule_brief's docstring is what happens otherwise: three copies
+    that had already drifted. `None` means "this rule is a decision, the
+    question does not apply"; "never" means "it is a fact and nobody has
+    confirmed it" — a distinction worth keeping, because the second is the
+    one worth acting on.
+    """
+    if not rule.verify_with:
+        return None
+    return rule.verified_at.date().isoformat() if rule.verified_at else "never"
+
+
 def rule_brief(rule: Rule, **extra) -> dict:
     """The shape a rule takes when it is SURFACED rather than opened.
 
@@ -331,6 +358,16 @@ def rule_brief(rule: Rule, **extra) -> dict:
         out["when_to_apply"] = rule.when_to_apply
     if rule.arose_from_id:
         out["arose_from_id"] = rule.arose_from_id
+    # Present ONLY on a rule that carries a check — its presence is the
+    # signal, and it says two things at once: this rule asserts a fact that
+    # can go false, and here is how long ago anyone confirmed it. The check
+    # text itself stays in get_rule; a listing needs to know WHICH rules can
+    # rot, not how to test them. "never" rather than null, per #2483: a key
+    # that reads as an unused capability is a different claim from a rule
+    # nobody has ever verified.
+    stamp = last_verified_label(rule)
+    if stamp:
+        out["last_verified"] = stamp
     out.update({k: v for k, v in extra.items() if v is not None})
     return out
 
@@ -436,6 +473,7 @@ async def create_rule(
     topic_id: int, user_id: int, title: str, statement: str,
     why: str = "", how_to_apply: str = "", order_index: int = 0,
     when_to_apply: str = "", tier: str = "always_on", arose_from_id: int = 0,
+    verify_with: str = "", expires_when: str = "",
 ) -> Rule:
     async with async_session() as session:
         await _assert_topic_owned(session, topic_id, user_id)
@@ -447,6 +485,8 @@ async def create_rule(
             tier=_valid_tier(tier),
             why=why or None,
             how_to_apply=how_to_apply or None,
+            verify_with=verify_with or None,
+            expires_when=expires_when or None,
             arose_from_id=arose_from_id or None,
             order_index=order_index,
         )
@@ -461,6 +501,7 @@ async def create_project_rule(
     project_id: int, user_id: int, title: str, statement: str,
     why: str = "", how_to_apply: str = "", order_index: int = 0,
     when_to_apply: str = "", tier: str = "always_on", arose_from_id: int = 0,
+    verify_with: str = "", expires_when: str = "",
 ) -> Rule:
     """Create a rule scoped to a single project (no rulebook ceremony).
 
@@ -478,6 +519,8 @@ async def create_project_rule(
             tier=_valid_tier(tier),
             why=why or None,
             how_to_apply=how_to_apply or None,
+            verify_with=verify_with or None,
+            expires_when=expires_when or None,
             arose_from_id=arose_from_id or None,
             order_index=order_index,
         )
@@ -681,7 +724,23 @@ async def get_rule(rule_id: int, user_id: int) -> Optional[Rule]:
         return await _fetch_owned_rule(session, rule_id, user_id)
 
 
-async def update_rule(rule_id: int, user_id: int, **fields) -> Optional[Rule]:
+async def update_rule(
+    rule_id: int, user_id: int, clear: Iterable[str] = (), **fields,
+) -> Optional[Rule]:
+    """Patch a rule. `clear` names fields to unset; **fields carries new values.
+
+    Clearing is EXPLICIT and separate because a nullable field cannot be
+    emptied by passing it. The MCP door reads "" as "leave this alone" — an
+    agent filling three fields must not wipe the other five — so a caller
+    there has no value that means "remove it", and a rule that stops being a
+    constraint genuinely needs its check removed. Naming the field is the one
+    form that cannot happen by accident.
+
+    Callers that DO have a meaningful empty value (the REST door, where a
+    cleared form input arrives as "") get the same outcome through
+    NULLABLE_RULE_TEXT normalisation below, so the two doors keep their own
+    idiom and agree about the result.
+    """
     async with async_session() as session:
         rule = await _fetch_owned_rule(session, rule_id, user_id)
         if rule is None:
@@ -689,10 +748,32 @@ async def update_rule(rule_id: int, user_id: int, **fields) -> Optional[Rule]:
         allowed = {
             "title", "statement", "why", "how_to_apply", "order_index",
             "when_to_apply", "tier", "arose_from_id",
+            "verify_with", "expires_when",
         }
+        check_before = rule.verify_with
+        for key in clear:
+            if key in allowed and key in NULLABLE_RULE_TEXT:
+                setattr(rule, key, None)
+            elif key == "arose_from_id":
+                setattr(rule, key, None)
         for key, value in fields.items():
-            if key in allowed and value is not None:
-                setattr(rule, key, _valid_tier(value) if key == "tier" else value)
+            if key not in allowed or value is None:
+                continue
+            if key == "tier":
+                value = _valid_tier(value)
+            elif key in NULLABLE_RULE_TEXT:
+                value = value or None
+            elif key == "arose_from_id":
+                value = value or None
+            setattr(rule, key, value)
+        # A verification stamp certifies A CHECK, not a rule. Rewrite or
+        # remove the check and the old stamp certifies something that no
+        # longer exists — so it is dropped, and the rule re-enters the sweep.
+        # The safe direction, for the same reason _valid_tier falls back to
+        # always_on: a rule wrongly listed as due costs one look, a rule
+        # wrongly vouched for costs the thing the sweep exists to catch.
+        if rule.verify_with != check_before:
+            rule.verified_at = None
         await session.commit()
         await session.refresh(rule)
         _refresh_rule_embedding(rule)
@@ -1280,3 +1361,150 @@ def rules_payload(applicable: dict) -> dict:
         "suppressed_topics": applicable.get("suppressed_topics", []),
         "excluded_always_on": applicable.get("excluded_always_on", []),
     }
+
+
+# ── The staleness sweep (milestone 312) ────────────────────────────────
+
+async def rules_due_for_verification(
+    user_id: int,
+    older_than_days: int = 0,
+    tier: str = "",
+    never_only: bool = False,
+) -> list[Rule]:
+    """Rules that carry a check, oldest verification first, never-checked top.
+
+    THE QUERY THIS MILESTONE EXISTS FOR. `verify_with` and `expires_when` are
+    storage; this is what turns them into something that gets acted on. The
+    307 audit cost a session and found four broken rules by luck — this makes
+    the same question a list, and staleness measurable by age instead of
+    discoverable by accident.
+
+    Ordered `verified_at` ASC NULLS FIRST: never-checked outranks
+    checked-long-ago, because a rule nobody has ever confirmed is a claim
+    with no evidence behind it at all.
+
+    Rules with no `verify_with` never appear. That is not an omission — they
+    are decisions, there is nothing to go and check, and listing them would
+    dilute the result until nobody reads it.
+
+    Ownership-scoped exactly like list_rules: a rule reached through an owned
+    rulebook, or scoped to an owned project. Rules have no sharing ACL in this
+    schema — no rule_shares, no rulebook_shares — so there is no wider set to
+    consult here, unlike notes and projects.
+
+    Args:
+        user_id: whose rules.
+        older_than_days: only rules last verified longer ago than this.
+            Never-checked rules always qualify — they are the most overdue
+            thing there is. 0 = no age filter.
+        tier: "always_on" or "conditional" to narrow. Raises on anything else
+            rather than falling back: _valid_tier's silent always_on default
+            is right for a WRITE (the safe direction is to keep binding), and
+            wrong for a FILTER, where it would quietly answer a different
+            question than the one asked.
+        never_only: only rules that have never been verified.
+    """
+    from datetime import datetime, timedelta, timezone
+
+    from scribe.models.project import Project
+
+    if tier and tier not in TIERS:
+        raise ValueError(f"tier must be one of {TIERS}, got {tier!r}")
+
+    async with async_session() as session:
+        stmt = (
+            select(Rule)
+            .outerjoin(RulebookTopic, Rule.topic_id == RulebookTopic.id)
+            .outerjoin(Rulebook, RulebookTopic.rulebook_id == Rulebook.id)
+            .outerjoin(Project, Rule.project_id == Project.id)
+            .where(
+                Rule.deleted_at.is_(None),
+                Rule.verify_with.is_not(None),
+                # One statement rather than two queries merged in Python, so
+                # the ordering below is the database's and cannot disagree
+                # with itself across the two halves of the XOR.
+                or_(
+                    and_(
+                        Rulebook.owner_user_id == user_id,
+                        Rulebook.deleted_at.is_(None),
+                        RulebookTopic.deleted_at.is_(None),
+                    ),
+                    Project.user_id == user_id,
+                ),
+            )
+        )
+        if tier:
+            stmt = stmt.where(Rule.tier == tier)
+        if never_only:
+            stmt = stmt.where(Rule.verified_at.is_(None))
+        elif older_than_days > 0:
+            cutoff = datetime.now(timezone.utc) - timedelta(days=older_than_days)
+            stmt = stmt.where(
+                or_(Rule.verified_at.is_(None), Rule.verified_at < cutoff)
+            )
+        stmt = stmt.order_by(Rule.verified_at.asc().nullsfirst(), Rule.id)
+        return list((await session.execute(stmt)).scalars().all())
+
+
+def verification_row(rule: Rule) -> dict:
+    """One row of the sweep — the CHECK in full, unlike rule_brief.
+
+    The opposite call from a listing: here the caller is about to go and run
+    the check, so the text they need is the point of the payload rather than
+    the bloat. `days_since` is computed rather than left to the reader,
+    because "2026-06-14" and "74 days" prompt different reactions and only
+    one of them is the question being asked.
+    """
+    from datetime import datetime, timezone
+
+    days = None
+    if rule.verified_at is not None:
+        stamp = rule.verified_at
+        if stamp.tzinfo is None:
+            stamp = stamp.replace(tzinfo=timezone.utc)
+        days = (datetime.now(timezone.utc) - stamp).days
+    return {
+        "id": rule.id,
+        "title": rule.title,
+        "statement": rule.statement,
+        "tier": rule.tier,
+        "topic_id": rule.topic_id,
+        "project_id": rule.project_id,
+        "when_to_apply": rule.when_to_apply or "",
+        "verify_with": rule.verify_with or "",
+        "expires_when": rule.expires_when or "",
+        "last_verified": last_verified_label(rule),
+        "days_since_verified": days,
+    }
+
+
+async def mark_rule_verified(
+    rule_id: int, user_id: int, still_true: bool = True,
+) -> Optional[Rule]:
+    """Stamp a rule as verified — or, when the check FAILED, refuse to.
+
+    A failing check is the outcome worth having, and the asymmetry is
+    deliberate: passing writes a stamp, failing writes nothing. There is no
+    "verified false" state to record, because a rule whose check failed is
+    not a rule in a special condition — it is a rule that is WRONG, and the
+    only honest resolutions are to correct it, retire it, or find out why.
+    Recording the failure as a flag would let it sit there being false with
+    the sweep quietly satisfied that someone had looked.
+
+    So a failed check leaves `verified_at` untouched, and the rule stays at
+    the top of the sweep until someone actually deals with it.
+
+    Returns None when the rule is not found, not owned, or carries no
+    `verify_with` — nothing to verify is a different answer from verified.
+    """
+    from datetime import datetime, timezone
+
+    async with async_session() as session:
+        rule = await _fetch_owned_rule(session, rule_id, user_id)
+        if rule is None or not rule.verify_with:
+            return None
+        if still_true:
+            rule.verified_at = datetime.now(timezone.utc)
+            await session.commit()
+            await session.refresh(rule)
+        return rule
diff --git a/tests/helpers.py b/tests/helpers.py
index e263e61..df77475 100644
--- a/tests/helpers.py
+++ b/tests/helpers.py
@@ -159,6 +159,11 @@ def fake_rule(**attrs) -> MagicMock:
         # `when_to_apply` and `arose_from_id` would be truthy MagicMocks and
         # rule_brief would attach both keys on every stand-in.
         "when_to_apply": None, "tier": "always_on", "arose_from_id": None,
+        # Same reason, and the same trap one field further on: an unnamed
+        # `verify_with` is a truthy MagicMock, so every stand-in rule would
+        # claim to carry a check and rule_brief would stamp a MagicMock date
+        # onto all of them. Most rules have none — that is the default here.
+        "verify_with": None, "expires_when": None, "verified_at": None,
         "order_index": 0, "created_at": _now(), "updated_at": _now(),
     }, attrs)
 
diff --git a/tests/test_integration_rule_verification.py b/tests/test_integration_rule_verification.py
new file mode 100644
index 0000000..8982153
--- /dev/null
+++ b/tests/test_integration_rule_verification.py
@@ -0,0 +1,275 @@
+"""Real-Postgres tests for a rule's CHECK — the write half (milestone 312).
+
+What mocks cannot prove, and what the staleness sweep depends on:
+
+1. **Empty means NULL.** The sweep asks for rules where `verify_with` is set.
+   A write that stored "" would leave a column that is neither null nor
+   content, and every rule ever touched through the REST door would answer
+   "yes, I have a check" — the sweep would list the whole rulebook and mean
+   nothing. Only a real column can show the difference; `to_dict`'s `or ""`
+   renders both the same.
+
+2. **Clearing is possible at all.** "" means "leave unchanged" at the MCP
+   door, so without an explicit clear there is no way to retire a check.
+
+3. **A stamp does not outlive the check it certifies.** Reword the check and
+   the old `verified_at` vouches for something that no longer exists.
+"""
+from datetime import datetime, timezone
+
+import pytest
+import pytest_asyncio
+
+from scribe.models import async_session
+from scribe.models.rulebook import Rule
+from scribe.services import rulebooks as rulebooks_svc
+from tests.helpers import ensure_user
+
+pytestmark = [pytest.mark.integration, pytest.mark.usefixtures("_dispose_engine")]
+
+
+@pytest_asyncio.fixture
+async def constraint():
+    """One rule carrying a check, already verified.
+
+    Verified at creation time rather than left null, because every assertion
+    here is about what happens to an EXISTING stamp — a fixture that started
+    null could pass all of them by doing nothing.
+    """
+    async with async_session() as s:
+        owner = await ensure_user(s, "verification_owner")
+        uid = owner.id
+        await s.commit()
+
+    book = await rulebooks_svc.create_rulebook(uid, "Environment facts")
+    topic = await rulebooks_svc.create_topic(book.id, uid, "ci")
+    rule = await rulebooks_svc.create_rule(
+        topic.id, uid, "The runner has no bash",
+        "Write every `run:` step in POSIX sh.",
+        verify_with="read the workflow's shell setting",
+        expires_when="the runner can be given a bash shell",
+    )
+    async with async_session() as s:
+        row = await s.get(Rule, rule.id)
+        row.verified_at = datetime(2026, 8, 1, tzinfo=timezone.utc)
+        await s.commit()
+    return {"uid": uid, "rule": rule.id}
+
+
+async def _row(rule_id: int) -> Rule:
+    async with async_session() as s:
+        return await s.get(Rule, rule_id)
+
+
+async def test_the_check_and_its_expiry_persist(constraint):
+    row = await _row(constraint["rule"])
+    assert row.verify_with == "read the workflow's shell setting"
+    assert row.expires_when == "the runner can be given a bash shell"
+    assert row.verified_at is not None
+
+
+async def test_an_empty_string_becomes_null_not_an_empty_column(constraint):
+    """The REST door's idiom: a cleared form input arrives as "".
+
+    NULL is asserted directly against the column rather than through to_dict,
+    which renders `None` and `""` identically — the difference this test
+    exists for would be invisible one layer up.
+    """
+    await rulebooks_svc.update_rule(
+        constraint["rule"], constraint["uid"], verify_with="", expires_when="",
+    )
+    row = await _row(constraint["rule"])
+    assert row.verify_with is None
+    assert row.expires_when is None
+
+
+async def test_naming_a_field_in_clear_empties_it(constraint):
+    """The MCP door's idiom, where "" already means "leave this alone"."""
+    await rulebooks_svc.update_rule(
+        constraint["rule"], constraint["uid"], clear=["verify_with"],
+    )
+    row = await _row(constraint["rule"])
+    assert row.verify_with is None
+    # expires_when was NOT named, so it survives — clearing is per-field, and
+    # a caller retiring one field must not lose the others.
+    assert row.expires_when == "the runner can be given a bash shell"
+
+
+async def test_rewording_the_check_drops_the_stamp(constraint):
+    """A stamp certifies a check, not a rule.
+
+    The safe direction, for the same reason _valid_tier falls back to
+    always_on: a rule wrongly listed as due costs one look, a rule wrongly
+    vouched for costs exactly what the sweep exists to catch.
+    """
+    await rulebooks_svc.update_rule(
+        constraint["rule"], constraint["uid"],
+        verify_with="read the runner's container shell, not the image's",
+    )
+    row = await _row(constraint["rule"])
+    assert row.verified_at is None
+
+
+async def test_clearing_the_check_drops_the_stamp(constraint):
+    await rulebooks_svc.update_rule(
+        constraint["rule"], constraint["uid"], clear=["verify_with"],
+    )
+    row = await _row(constraint["rule"])
+    assert row.verified_at is None
+
+
+async def test_editing_anything_else_leaves_the_stamp_alone(constraint):
+    """The other half of the rule above, and the one that keeps it useful.
+
+    If any edit reset the stamp, a rulebook tidy-up would put every constraint
+    back at the top of the sweep and the ordering would carry no information.
+    Only the check's own text invalidates its verification.
+    """
+    await rulebooks_svc.update_rule(
+        constraint["rule"], constraint["uid"],
+        why="act_runner picks the shell, and the image's SHELL directive "
+            "applies to the build, not to `run:`.",
+        expires_when="the runner grows a shell setting",
+    )
+    row = await _row(constraint["rule"])
+    assert row.verified_at is not None
+    assert row.why.startswith("act_runner picks the shell")
+
+
+# ── the sweep itself (step 3) ──────────────────────────────────────────
+
+@pytest_asyncio.fixture
+async def rulebook_of_three():
+    """A decision, a never-checked constraint, and a long-ago-checked one.
+
+    Three rows because the sweep's whole value is an ORDER, and an order
+    cannot be asserted with fewer.
+    """
+    async with async_session() as s:
+        owner = await ensure_user(s, "sweep_owner")
+        uid = owner.id
+        await s.commit()
+
+    book = await rulebooks_svc.create_rulebook(uid, "Sweep fixture")
+    topic = await rulebooks_svc.create_topic(book.id, uid, "mixed")
+    decision = await rulebooks_svc.create_rule(
+        topic.id, uid, "dev is home", "Work directly on dev.",
+    )
+    never = await rulebooks_svc.create_rule(
+        topic.id, uid, "The runner has no bash", "Use POSIX sh.",
+        verify_with="read the workflow's shell setting",
+    )
+    stale = await rulebooks_svc.create_rule(
+        topic.id, uid, "Bumps need a dashboard tick", "Tick it first.",
+        verify_with="cat CI-runner/renovate/config.js",
+        tier="conditional",
+    )
+    async with async_session() as s:
+        row = await s.get(Rule, stale.id)
+        row.verified_at = datetime(2026, 1, 1, tzinfo=timezone.utc)
+        await s.commit()
+    return {
+        "uid": uid, "decision": decision.id,
+        "never": never.id, "stale": stale.id,
+    }
+
+
+async def test_a_rule_with_no_check_is_never_in_the_sweep(rulebook_of_three):
+    """The common case, and the one that keeps the list worth reading.
+
+    Most rules are decisions. If they appeared here the sweep would be the
+    rulebook, and nobody would read it twice.
+    """
+    rules = await rulebooks_svc.rules_due_for_verification(rulebook_of_three["uid"])
+    assert rulebook_of_three["decision"] not in [r.id for r in rules]
+
+
+async def test_never_checked_outranks_checked_long_ago(rulebook_of_three):
+    """NULLS FIRST is the ordering decision this surface turns on.
+
+    Postgres sorts NULLs LAST by default on an ASC ordering, which would put
+    the rules nobody has ever confirmed at the BOTTOM — behind every rule
+    that at least once had someone look at it. That is exactly backwards: a
+    claim with no evidence at all outranks an old one.
+    """
+    ids = [r.id for r in await rulebooks_svc.rules_due_for_verification(
+        rulebook_of_three["uid"]
+    )]
+    assert ids.index(rulebook_of_three["never"]) < ids.index(rulebook_of_three["stale"])
+
+
+async def test_verifying_a_rule_moves_it_off_the_top(rulebook_of_three):
+    """The loop closing: check it, stamp it, and it stops being the question."""
+    await rulebooks_svc.mark_rule_verified(
+        rulebook_of_three["never"], rulebook_of_three["uid"], still_true=True,
+    )
+    ids = [r.id for r in await rulebooks_svc.rules_due_for_verification(
+        rulebook_of_three["uid"]
+    )]
+    # Still present — verified is not retired, and it will come due again.
+    assert rulebook_of_three["never"] in ids
+    assert ids.index(rulebook_of_three["stale"]) < ids.index(rulebook_of_three["never"])
+
+
+async def test_a_failed_check_writes_nothing(rulebook_of_three):
+    """The asymmetry that keeps the sweep honest.
+
+    There is no "verified false" state, because a rule whose check failed is
+    not in a special condition — it is WRONG. Recording the failure would let
+    it sit there being false with the sweep satisfied that someone looked.
+    """
+    before = await _row(rulebook_of_three["stale"])
+    await rulebooks_svc.mark_rule_verified(
+        rulebook_of_three["stale"], rulebook_of_three["uid"], still_true=False,
+    )
+    after = await _row(rulebook_of_three["stale"])
+    assert after.verified_at == before.verified_at
+
+
+async def test_a_rule_with_no_check_cannot_be_verified(rulebook_of_three):
+    """Nothing to verify is a different answer from verified — and stamping
+    one would put a decision into a sweep it has no business being in."""
+    assert await rulebooks_svc.mark_rule_verified(
+        rulebook_of_three["decision"], rulebook_of_three["uid"],
+    ) is None
+
+
+async def test_never_only_and_the_age_filter_narrow_to_what_they_say(rulebook_of_three):
+    uid = rulebook_of_three["uid"]
+    # Membership, not equality: the integration lane shares one database for
+    # the whole run and this fixture is function-scoped, so this owner has
+    # accumulated rules from earlier tests. Asserting the exact list would
+    # pass alone and fail in the suite.
+    never_ids = [r.id for r in await rulebooks_svc.rules_due_for_verification(
+        uid, never_only=True,
+    )]
+    assert rulebook_of_three["never"] in never_ids
+    assert rulebook_of_three["stale"] not in never_ids
+    assert rulebook_of_three["decision"] not in never_ids
+
+    # A rule checked in January is well past any sane window; one never
+    # checked always qualifies, because it is the most overdue thing there is.
+    aged = [r.id for r in await rulebooks_svc.rules_due_for_verification(
+        uid, older_than_days=30,
+    )]
+    assert rulebook_of_three["stale"] in aged
+    assert rulebook_of_three["never"] in aged
+
+
+async def test_the_tier_filter_narrows_to_one_tier(rulebook_of_three):
+    ids = [r.id for r in await rulebooks_svc.rules_due_for_verification(
+        rulebook_of_three["uid"], tier="conditional",
+    )]
+    assert rulebook_of_three["stale"] in ids
+    assert rulebook_of_three["never"] not in ids
+
+
+async def test_another_users_rules_are_not_in_your_sweep(rulebook_of_three):
+    """Rules are ownership-scoped: there is no rule-sharing ACL in this
+    schema, so the only correct answer is your own rules."""
+    async with async_session() as s:
+        stranger = await ensure_user(s, "sweep_stranger")
+        sid = stranger.id
+        await s.commit()
+
+    assert await rulebooks_svc.rules_due_for_verification(sid) == []
diff --git a/tests/test_integration_task_kind_spike.py b/tests/test_integration_task_kind_spike.py
new file mode 100644
index 0000000..3f8a2ea
--- /dev/null
+++ b/tests/test_integration_task_kind_spike.py
@@ -0,0 +1,74 @@
+"""Real-Postgres test that the CHECK actually accepts 'spike' (0091).
+
+Rule 36 exists because the value and the constraint can drift apart: the
+code starts writing a new kind while the database still refuses it, and
+nothing catches it until a write fails in front of someone. A mock cannot
+show that — it has no CHECK — so the constraint gets its own real-DB test,
+the same way migration 0090's nullability did.
+
+The negative half matters as much as the positive one. A test that only
+proves 'spike' is accepted would also pass against a table with NO
+constraint at all, which is the other way this goes wrong.
+"""
+import pytest
+import pytest_asyncio
+from sqlalchemy.exc import IntegrityError
+
+from scribe.models import async_session
+from scribe.models.note import Note
+from tests.helpers import ensure_user
+
+pytestmark = [pytest.mark.integration, pytest.mark.usefixtures("_dispose_engine")]
+
+
+@pytest_asyncio.fixture
+async def owner_id():
+    async with async_session() as s:
+        owner = await ensure_user(s, "spike_owner")
+        uid = owner.id
+        await s.commit()
+    return uid
+
+
+async def _write(uid: int, kind: str) -> int:
+    async with async_session() as s:
+        # No is_task=: it is a derived read-only property (a note IS a task
+        # when status is not None), so passing it raises rather than being
+        # ignored. status="todo" is what makes this a task.
+        note = Note(
+            user_id=uid, title=f"kind {kind}", body="",
+            status="todo", task_kind=kind,
+        )
+        s.add(note)
+        await s.commit()
+        return note.id
+
+
+async def test_a_spike_can_be_written(owner_id):
+    note_id = await _write(owner_id, "spike")
+    async with async_session() as s:
+        assert (await s.get(Note, note_id)).task_kind == "spike"
+
+
+async def test_the_older_kinds_still_write(owner_id):
+    """0091 widens the whitelist; it must not narrow it by accident.
+
+    'plan' is retired — plans are milestones since 0066 — but historical
+    plan-tasks still carry it, and a row that cannot be rewritten is a row
+    that cannot be edited, restored, or migrated.
+    """
+    for kind in ("work", "issue", "plan"):
+        note_id = await _write(owner_id, kind)
+        async with async_session() as s:
+            assert (await s.get(Note, note_id)).task_kind == kind
+
+
+async def test_an_unknown_kind_is_still_refused(owner_id):
+    """The half that proves a constraint is there at all.
+
+    Without this, every assertion above would pass just as happily against a
+    table whose CHECK had been dropped and never re-added — which is exactly
+    the failure rule 36 is written against.
+    """
+    with pytest.raises(IntegrityError):
+        await _write(owner_id, "investigation")
diff --git a/tests/test_mcp_tool_rulebooks.py b/tests/test_mcp_tool_rulebooks.py
index 33fbd58..c922a06 100644
--- a/tests/test_mcp_tool_rulebooks.py
+++ b/tests/test_mcp_tool_rulebooks.py
@@ -115,7 +115,46 @@ async def test_update_rule_only_sends_non_default_fields():
         await update_rule(rule_id=1, statement="new statement")
     args, kwargs = mock.call_args
     assert args == (1, 7)
-    assert kwargs == {"statement": "new statement"}
+    # `clear` is always forwarded — an empty tuple is "clear nothing", which is
+    # a value, not an absent argument. Everything the caller left at its
+    # default stays out: that is the property this test pins.
+    assert kwargs == {"statement": "new statement", "clear": ()}
+
+
+@pytest.mark.asyncio
+async def test_update_rule_forwards_the_fields_named_for_clearing():
+    """Naming a field is the only way to empty it through this door.
+
+    "" means "leave unchanged" here, so a caller has no value that means
+    "remove it" — which is what makes an explicit list necessary and what
+    stops a partial update from wiping the fields it did not mention.
+    """
+    rule = fake_rule(id=100, title="r", statement="s", topic_id=10)
+    mock = AsyncMock(return_value=rule)
+    with patch("scribe.mcp.tools.rulebooks.rulebooks_svc.update_rule", mock), _plain_detail():
+        from scribe.mcp.tools.rulebooks import update_rule
+        await update_rule(rule_id=1, clear_fields=["verify_with"])
+    _args, kwargs = mock.call_args
+    assert kwargs == {"clear": ["verify_with"]}
+
+
+@pytest.mark.asyncio
+async def test_update_rule_sends_the_check_fields_when_given():
+    rule = fake_rule(id=100, title="r", statement="s", topic_id=10)
+    mock = AsyncMock(return_value=rule)
+    with patch("scribe.mcp.tools.rulebooks.rulebooks_svc.update_rule", mock), _plain_detail():
+        from scribe.mcp.tools.rulebooks import update_rule
+        await update_rule(
+            rule_id=1,
+            verify_with="cat CI-runner/renovate/config.js",
+            expires_when="approval is turned off",
+        )
+    _args, kwargs = mock.call_args
+    assert kwargs == {
+        "verify_with": "cat CI-runner/renovate/config.js",
+        "expires_when": "approval is turned off",
+        "clear": (),
+    }
 
 
 @pytest.mark.asyncio
@@ -178,13 +217,20 @@ async def test_unsubscribe_project_from_rulebook_calls_service():
     assert mock.called
 
 
-def test_register_attaches_all_sixteen_tools():
-    """register(mcp) should call mcp.tool(name=...) for all 16 tools."""
+def test_register_attaches_every_tool():
+    """Every tool in the module reaches the server.
+
+    The count is the guard: a function added to the module but left out of
+    register()'s tuple is invisible to callers and raises nothing. The name
+    said "sixteen" for ten tools' worth of growth — the number lives in the
+    assertion, not the title, so it cannot drift again.
+    """
     from scribe.mcp.tools.rulebooks import register
     mcp = FakeMCP()
 
     register(mcp)
-    assert len(mcp.names) == 26   # +relate_rules/unrelate_rules (milestone 307)
+    # 26 through milestone 307, +2 for the staleness sweep (milestone 312).
+    assert len(mcp.names) == 28
     # spot-check a few names
     assert "list_rulebooks" in mcp.names
     assert "create_rule" in mcp.names
@@ -195,6 +241,9 @@ def test_register_attaches_all_sixteen_tools():
     assert "include_always_on_rulebook" in mcp.names
     assert "create_project_rule" in mcp.names
     assert "suppress_rule_for_project" in mcp.names
+    # milestone 312: the sweep, and the stamp that answers it
+    assert "rules_due_for_verification" in mcp.names
+    assert "mark_rule_verified" in mcp.names
     assert "unsuppress_rule_for_project" in mcp.names
     assert "suppress_topic_for_project" in mcp.names
     assert "unsuppress_topic_for_project" in mcp.names
diff --git a/tests/test_mcp_tool_tasks_kind.py b/tests/test_mcp_tool_tasks_kind.py
index 4b123f4..832f013 100644
--- a/tests/test_mcp_tool_tasks_kind.py
+++ b/tests/test_mcp_tool_tasks_kind.py
@@ -33,3 +33,17 @@ async def test_list_tasks_kind_empty_means_no_filter():
         from scribe.mcp.tools.tasks import list_tasks
         await list_tasks()
     assert mock.call_args.kwargs["task_kind"] is None
+
+
+@pytest.mark.asyncio
+async def test_create_task_passes_spike():
+    """The kind a failed rule-check asks for (milestone 312).
+
+    Time-boxed, and its output is knowledge rather than a change — filing one
+    as `work` makes a finished investigation look like an abandoned change.
+    """
+    mock = AsyncMock(return_value=fake_note(task_kind="spike"))
+    with patch("scribe.mcp.tools.tasks.notes_svc.create_note", mock):
+        from scribe.mcp.tools.tasks import create_task
+        await create_task(title="Can the runner be given a bash shell?", kind="spike")
+    assert mock.call_args.kwargs["task_kind"] == "spike"
diff --git a/tests/test_services_backup.py b/tests/test_services_backup.py
index 3eaac1c..a5d78bc 100644
--- a/tests/test_services_backup.py
+++ b/tests/test_services_backup.py
@@ -1,10 +1,13 @@
-"""Unit tests for the v4 backup export contract.
+"""Unit tests for the backup export contract.
 
-CI runs pytest with no database, so these cover the parts that don't need one:
-the version/coverage constants, the pure join-table row helpers, and the export
-dict shape (via a mocked session). Full FK-remapping round-trip is exercised
-manually against a real DB (export a backup, confirm rulebooks appear).
+This is the no-database lane, so these cover the parts that need none: the
+version/coverage constants, the pure row helpers, and the export dict shape
+(via a mocked session). The full FK-remapping round-trip needs real Postgres
+and belongs in a `@pytest.mark.integration` module — it is not written yet,
+which is why every row helper here is a plain function that can be tested
+without a session.
 """
+from datetime import datetime, timezone
 from types import SimpleNamespace
 from unittest.mock import patch
 
@@ -132,3 +135,58 @@ def test_supersession_rows_serialise_the_pair():
         {"superseder_id": 9, "superseded_id": 4},
         {"superseder_id": 9, "superseded_id": 5},
     ]
+
+
+def test_rule_rows_carry_the_verification_fields():
+    """A rule's check must survive a backup.
+
+    `verify_with`/`expires_when`/`verified_at` (milestone 312) say whether a
+    rule is a fact that can go false and when it was last confirmed. A backup
+    that drops them restores a rulebook that has forgotten which of its rules
+    can rot — the exact blindness the fields were added to end.
+
+    Column additions do not bump BACKUP_VERSION; only new SECTIONS do. Same
+    call made for when_to_apply/tier/arose_from_id in 0088 (commit 6ddb8bf).
+    """
+    checked = datetime(2026, 8, 27, 12, 0, tzinfo=timezone.utc)
+    row = SimpleNamespace(
+        id=1, topic_id=2, project_id=None, title="t", statement="s",
+        why="w", how_to_apply="h", order_index=0,
+        when_to_apply="when", tier="conditional",
+        verify_with="cat some/file", expires_when="the file grows a shell",
+        verified_at=checked, arose_from_id=99,
+        created_at=checked, updated_at=checked,
+    )
+    out = backup._rule_rows([row])[0]
+
+    assert out["verify_with"] == "cat some/file"
+    assert out["expires_when"] == "the file grows a shell"
+    assert out["verified_at"] == checked.isoformat()
+    # Provenance was exported from 0088 onward but silently dropped on the way
+    # back IN until milestone 312. Export side asserted here; the restore side
+    # remaps it through note_id_map.
+    assert out["arose_from_id"] == 99
+
+
+def test_rule_rows_keep_an_unverified_rule_unverified():
+    """NULL verified_at means never checked, and it must round-trip as null.
+
+    _dt substitutes now() so created_at/updated_at are never null. Reusing it
+    here would restore a rule nobody ever checked as though it had just been
+    checked — dropping it to the BOTTOM of the sweep it should top. That is
+    why _dt_or_none exists.
+    """
+    row = SimpleNamespace(
+        id=1, topic_id=2, project_id=None, title="t", statement="s",
+        why=None, how_to_apply=None, order_index=0,
+        when_to_apply=None, tier="always_on",
+        verify_with=None, expires_when=None, verified_at=None,
+        arose_from_id=None,
+        created_at=datetime(2026, 8, 27, tzinfo=timezone.utc),
+        updated_at=datetime(2026, 8, 27, tzinfo=timezone.utc),
+    )
+    assert backup._rule_rows([row])[0]["verified_at"] is None
+    assert backup._dt_or_none(None) is None
+    assert backup._dt_or_none("2026-08-27T12:00:00+00:00") == datetime(
+        2026, 8, 27, 12, 0, tzinfo=timezone.utc
+    )
diff --git a/tests/test_services_rulebooks.py b/tests/test_services_rulebooks.py
index b7de1ad..eeaeb57 100644
--- a/tests/test_services_rulebooks.py
+++ b/tests/test_services_rulebooks.py
@@ -392,3 +392,116 @@ def test_an_unknown_tier_falls_back_to_binding():
     assert _valid_tier("Conditional") == "always_on"
     assert _valid_tier("") == "always_on"
     assert _valid_tier("occasionally") == "always_on"
+
+
+# ── verify_with / expires_when (milestone 312) ──────────────────────────
+
+def test_a_rule_with_no_check_says_nothing_about_verification():
+    """The empty case is the COMMON case, and it must stay silent.
+
+    Most rules are decisions: they have no truth value and there is nothing to
+    go and check. If a brief carried `last_verified` for those too, the signal
+    would be worthless — every rule would look like something someone ought to
+    be verifying, and the handful that genuinely rot would stop standing out.
+    """
+    from scribe.services.rulebooks import last_verified_label, rule_brief
+
+    rule = fake_rule()
+    assert last_verified_label(rule) is None
+    assert "last_verified" not in rule_brief(rule)
+
+
+def test_an_unverified_constraint_reads_never_rather_than_null():
+    """#2483 again: a null key reads as a capability going unused. "never" is
+    a different and much stronger claim — this rule asserts a fact about
+    someone else's software and nobody has ever confirmed it."""
+    from scribe.services.rulebooks import last_verified_label, rule_brief
+
+    rule = fake_rule(verify_with="cat CI-runner/renovate/config.js")
+    assert last_verified_label(rule) == "never"
+    assert rule_brief(rule)["last_verified"] == "never"
+
+
+def test_a_verified_constraint_reports_the_date_it_was_checked():
+    """A date, not a stamp — the question is "how old is this", the same call
+    rule_brief makes for updated_at."""
+    from scribe.services.rulebooks import last_verified_label
+
+    rule = fake_rule(
+        verify_with="cat CI-runner/renovate/config.js",
+        verified_at=datetime(2026, 8, 27, 11, 46, tzinfo=timezone.utc),
+    )
+    assert last_verified_label(rule) == "2026-08-27"
+
+
+def test_the_check_text_itself_never_enters_a_listing():
+    """A listing says WHICH rules can rot, not how to test them. The check can
+    be a long command; multiplied across an always-on set it is the same bloat
+    `why` and `how_to_apply` are kept out of a brief to avoid."""
+    from scribe.services.rulebooks import rule_brief
+
+    out = rule_brief(fake_rule(
+        verify_with="a very long command " * 20,
+        expires_when="the runner learns a new shell",
+    ))
+    assert "verify_with" not in out
+    assert "expires_when" not in out
+
+
+# ── the sweep's row shape (milestone 312 step 3) ────────────────────────
+
+def test_a_sweep_row_carries_the_check_in_full():
+    """The OPPOSITE call from rule_brief, and deliberately so.
+
+    A listing omits the depth because nobody reading it wants to act on one
+    rule. A sweep row exists to be acted on — the reader is about to go and
+    run the check — so the text is the payload's point, not its bloat.
+    """
+    from scribe.services.rulebooks import verification_row
+
+    row = verification_row(fake_rule(
+        verify_with="cat CI-runner/renovate/config.js",
+        expires_when="dependencyDashboardApproval is turned off",
+        when_to_apply="when a dependency bump is in play",
+    ))
+    assert row["verify_with"] == "cat CI-runner/renovate/config.js"
+    assert row["expires_when"] == "dependencyDashboardApproval is turned off"
+    assert row["when_to_apply"] == "when a dependency bump is in play"
+    assert row["tier"] == "always_on"
+
+
+def test_never_verified_reports_no_day_count_rather_than_zero():
+    """"Never" is not "0 days ago" — the second reads as freshly checked.
+
+    Getting this wrong would invert the row's meaning for exactly the rules
+    that most need attention.
+    """
+    from scribe.services.rulebooks import verification_row
+
+    row = verification_row(fake_rule(verify_with="read the workflow"))
+    assert row["last_verified"] == "never"
+    assert row["days_since_verified"] is None
+
+
+def test_a_verified_row_counts_the_days():
+    from datetime import timedelta
+
+    from scribe.services.rulebooks import verification_row
+
+    row = verification_row(fake_rule(
+        verify_with="read the workflow",
+        verified_at=datetime.now(timezone.utc) - timedelta(days=74, hours=1),
+    ))
+    assert row["days_since_verified"] == 74
+
+
+@pytest.mark.asyncio
+async def test_an_unrecognised_tier_filter_raises_rather_than_narrowing():
+    """_valid_tier's silent always_on fallback is right for a WRITE — a typo
+    should leave a rule binding. It is wrong for a FILTER, where the same
+    fallback would quietly answer a different question than the one asked and
+    return a short list that looks like good news."""
+    from scribe.services.rulebooks import rules_due_for_verification
+
+    with pytest.raises(ValueError, match="tier must be one of"):
+        await rules_due_for_verification(7, tier="occasionally")