diff --git a/.flatbread-proof/issues/iss-writedecision-with-supersedes-leaves-the-superse--by624gyf21ex42sv.md b/.flatbread-proof/issues/iss-writedecision-with-supersedes-leaves-the-superse--by624gyf21ex42sv.md
index 9ba4d4a9..2006c8ab 100644
--- a/.flatbread-proof/issues/iss-writedecision-with-supersedes-leaves-the-superse--by624gyf21ex42sv.md
+++ b/.flatbread-proof/issues/iss-writedecision-with-supersedes-leaves-the-superse--by624gyf21ex42sv.md
@@ -3,10 +3,12 @@ id: iss-writedecision-with-supersedes-leaves-the-superse--by624gyf21ex42sv
 effort: eff-effort-graph-memory-and-agent-wedge--szeqvmgqjqnhd002
 title: WriteDecision with supersedes leaves the superseded Decision in state accepted
 kind: defect
-status: open
+status: resolved
 created_at: '2026-07-26T05:07:15.240Z'
 derives_from:
   - fnd-supersession-transitions-decision-state-on-the-r--2m807tcfjz2jz9gt
+resolved_by:
+  - dec-use-semantic-mutations-and-a-standalone-writer--2d0m3tkqhad4yyhr
 ---
 
 ## Problem
diff --git a/packages/proof/src/__tests__/planner.test.ts b/packages/proof/src/__tests__/planner.test.ts
index 52fa1d58..57b585f8 100644
--- a/packages/proof/src/__tests__/planner.test.ts
+++ b/packages/proof/src/__tests__/planner.test.ts
@@ -166,6 +166,41 @@ test('11 WriteFinding with supersedes', (t) => {
   );
   t.deepEqual(w[1].beforeBytes, s.getRawBytes(ids.finding));
 });
+test('WriteDecision with supersedes transitions the target state', (t) => {
+  const target = record(ids.decision, 'decision', {
+    id: ids.decision,
+    effort: E,
+    title: 'Old',
+    state: 'accepted',
+    created_at: '2025-01-01T00:00:00.000Z',
+  });
+  const s = snap([target]);
+  const w = planMutation(
+    {
+      type: 'WriteDecision',
+      id: ids.decision2,
+      effort: E,
+      title: 'New',
+      body: '',
+      supersedes: [ids.decision],
+    },
+    s,
+    '/root',
+    now
+  );
+  const targetFrontmatter = parseDocument(
+    w[1].afterBytes,
+    'decision'
+  ).frontmatter;
+
+  t.deepEqual(
+    w.map((write) => write.id),
+    [ids.decision2, ids.decision]
+  );
+  t.is(targetFrontmatter.state, 'superseded');
+  t.deepEqual(targetFrontmatter.superseded_by, [ids.decision2]);
+  t.deepEqual(w[1].beforeBytes, s.getRawBytes(ids.decision));
+});
 test('12 WriteDecision with invalidates', (t) => {
   const target = record(ids.finding, 'finding', {
     id: ids.finding,
diff --git a/packages/proof/src/__tests__/writer.test.ts b/packages/proof/src/__tests__/writer.test.ts
index 05fc0b2c..80c900d6 100644
--- a/packages/proof/src/__tests__/writer.test.ts
+++ b/packages/proof/src/__tests__/writer.test.ts
@@ -97,6 +97,7 @@ test('WriteDecision with supersedes materializes superseded_by on the target fil
   });
   t.is(result.touched.length, 2);
   const target = await readFrontmatter(root, `decisions/${older}.md`);
+  t.is(target.data.state, 'superseded');
   t.deepEqual(target.data.superseded_by, [soleId(result)]);
   const newer = result.artifacts.find((a) => a.operation === 'created')!;
   t.deepEqual(newer.frontmatter.supersedes, [older]);
diff --git a/packages/proof/src/planner.ts b/packages/proof/src/planner.ts
index 4b006cc9..8c64e318 100644
--- a/packages/proof/src/planner.ts
+++ b/packages/proof/src/planner.ts
@@ -359,7 +359,10 @@ export function planMutation(
         const reverse =
           edge === 'supersedes' ? 'superseded_by' : 'invalidated_by';
         const current =
-          reverseUpdates.get(target.id)?.frontmatter ?? target.frontmatter;
+          reverseUpdates.get(target.id)?.frontmatter ??
+          (edge === 'supersedes' && target.kind === 'decision'
+            ? supersedeDecisionLifecycle(snapshot, target.id).nextFrontmatter
+            : target.frontmatter);
         reverseUpdates.set(target.id, {
           target,
           frontmatter: {