diff --git a/server/store.js b/server/store.js
index 029d103..cd73259 100644
--- a/server/store.js
+++ b/server/store.js
@@ -258,14 +258,17 @@ function setRestoreState(patch) {
 }
 
 // Mark a session as having produced a real completed turn. Codex only writes a
-// resumable rollout file once a turn reports usage; a non-subagent entry with
-// usage is our proxy-side signal for "this session can be resumed". Monotonic:
-// once true it never flips back.
+// resumable rollout file once a turn produces output; turns that billed input
+// but emitted zero output (hung WS turns, cross-session retries) leave no
+// rollout file, so `usage` alone is a false signal — status and stopReason are
+// unreliable too (verified against ~/.codex/sessions ground truth, issue #44).
+// output_tokens > 0 on a non-subagent entry is the only discriminator that
+// matches. Monotonic: once true it never flips back.
 function markSessionUsage(entry) {
   const sid = entry?.sessionId;
   if (!sid || NON_RESUMABLE_SESSIONS.has(sid)) return;
   if (entry.isSubagent) return;
-  if (!entry.usage) return;
+  if (!(entry.usage?.output_tokens > 0)) return;
   const meta = sessionMeta[sid] || (sessionMeta[sid] = {});
   meta.hasUsage = true;
 }
diff --git a/test/restore.test.js b/test/restore.test.js
index ce76926..2d47cc9 100644
--- a/test/restore.test.js
+++ b/test/restore.test.js
@@ -182,7 +182,7 @@ describe('restoreFromLogs — maxContext re-inference for legacy entries', () =>
 
 // Resume-eligibility must survive a restart: it is rebuilt purely from the
 // index (no rollout-file probing), so a codex session is resumable iff the
-// index holds a non-subagent usage turn for it.
+// index holds a non-subagent turn with output_tokens > 0 for it.
 describe('restoreFromLogs — codex resume eligibility', () => {
   const config = require('../server/config');
   const store = require('../server/store');
@@ -213,7 +213,7 @@ describe('restoreFromLogs — codex resume eligibility', () => {
     await config.storage.appendIndex(JSON.stringify({
       id: '2026-05-20T10-00-00-000', ts: '10:00:00', sessionId: sid,
       provider: 'openai', agent: 'codex', model: 'gpt-5',
-      usage: { input_tokens: 42 }, isSubagent: false,
+      usage: { input_tokens: 42, output_tokens: 12 }, isSubagent: false,
       isSSE: true, status: 200, receivedAt: 1779000000000,
     }) + '\n');
 
@@ -241,7 +241,7 @@ describe('restoreFromLogs — codex resume eligibility', () => {
     await config.storage.appendIndex(JSON.stringify({
       id: '2026-05-20T12-01-00-000', ts: '12:01:00', sessionId: sid,
       provider: 'openai', agent: 'codex', model: 'gpt-5',
-      usage: { input_tokens: 7 }, isSubagent: false,
+      usage: { input_tokens: 7, output_tokens: 2 }, isSubagent: false,
       isSSE: true, status: 200, receivedAt: 1779000060000,
     }) + '\n');
 
@@ -250,6 +250,27 @@ describe('restoreFromLogs — codex resume eligibility', () => {
     assert.equal(summarizeEntry(first).resumeCommand, `codex resume ${sid}`);
   });
 
+  it('a codex session with only a billed zero-output turn is not resumable after restore', async () => {
+    store.entries.length = 0;
+    const sid = 'codex-restore-zero-output';
+    // Issue #44 specimen 2: hung WS turn — input billed, zero output, no
+    // rollout file on disk. Restore must not resurrect the resume button.
+    await config.storage.appendIndex(JSON.stringify({
+      id: '2026-05-20T13-00-00-000', ts: '13:00:00', sessionId: sid,
+      provider: 'openai', agent: 'codex', model: 'gpt-5',
+      usage: { input_tokens: 9953, output_tokens: 0 }, isSubagent: false,
+      isSSE: true, status: 499, receivedAt: 1779000000000,
+    }) + '\n');
+
+    await restoreFromLogs();
+    assert.deepEqual(
+      store.computeSessionResume(sid, 'openai'),
+      { resumable: false, resumeCommand: null },
+    );
+    const summary = summarizeEntry(store.entries.find(e => e.sessionId === sid));
+    assert.equal(summary.resumeCommand, null);
+  });
+
   it('a codex session with only a 502-style turn (no usage) is not resumable', async () => {
     store.entries.length = 0;
     const sid = 'codex-restore-502';
diff --git a/test/sse-broadcast.test.js b/test/sse-broadcast.test.js
index debf009..fdaaa2b 100644
--- a/test/sse-broadcast.test.js
+++ b/test/sse-broadcast.test.js
@@ -23,7 +23,7 @@ describe('sse-broadcast', () => {
 
       // A real completed turn flips the session to resumable; summarizeEntry both
       // records the signal and reads it back (single source of truth).
-      const withUsage = summarizeEntry({ id: 'r2', sessionId: sid, provider: 'openai', usage: { input_tokens: 9 }, isSubagent: false });
+      const withUsage = summarizeEntry({ id: 'r2', sessionId: sid, provider: 'openai', usage: { input_tokens: 9, output_tokens: 4 }, isSubagent: false });
       assert.equal(withUsage.resumable, true);
       assert.equal(withUsage.resumeCommand, `codex resume ${sid}`);
 
diff --git a/test/store.test.js b/test/store.test.js
index 9045dce..0a26103 100644
--- a/test/store.test.js
+++ b/test/store.test.js
@@ -68,7 +68,7 @@ describe('store', () => {
     });
 
     it('an unknown provider fails closed (no resume command)', () => {
-      store.markSessionUsage({ sessionId: 'future-sid', isSubagent: false, usage: { input_tokens: 5 } });
+      store.markSessionUsage({ sessionId: 'future-sid', isSubagent: false, usage: { input_tokens: 5, output_tokens: 3 } });
       assert.deepEqual(store.computeSessionResume('future-sid', 'future-provider'), { resumable: false, resumeCommand: null });
     });
 
@@ -81,16 +81,16 @@ describe('store', () => {
       assert.deepEqual(r, { resumable: false, resumeCommand: null });
     });
 
-    it('codex session becomes resumable after a non-subagent usage turn', () => {
+    it('codex session becomes resumable after a non-subagent turn with output', () => {
       const sid = 'codex-sid-withusage';
-      store.markSessionUsage({ sessionId: sid, isSubagent: false, usage: { input_tokens: 5 } });
+      store.markSessionUsage({ sessionId: sid, isSubagent: false, usage: { input_tokens: 5, output_tokens: 3 } });
       const r = store.computeSessionResume(sid, 'openai');
       assert.deepEqual(r, { resumable: true, resumeCommand: `codex resume ${sid}` });
     });
 
     it('subagent usage alone does not make a codex session resumable', () => {
       const sid = 'codex-sid-subonly';
-      store.markSessionUsage({ sessionId: sid, isSubagent: true, usage: { input_tokens: 5 } });
+      store.markSessionUsage({ sessionId: sid, isSubagent: true, usage: { input_tokens: 5, output_tokens: 3 } });
       assert.deepEqual(store.computeSessionResume(sid, 'openai'), { resumable: false, resumeCommand: null });
     });
 
@@ -100,16 +100,30 @@ describe('store', () => {
       assert.deepEqual(store.computeSessionResume(sid, 'openai'), { resumable: false, resumeCommand: null });
     });
 
+    it('legacy usage without an output_tokens field fails closed', () => {
+      const sid = 'codex-sid-legacy-no-output-field';
+      store.markSessionUsage({ sessionId: sid, isSubagent: false, usage: { input_tokens: 5 } });
+      assert.deepEqual(store.computeSessionResume(sid, 'openai'), { resumable: false, resumeCommand: null });
+    });
+
+    it('a billed zero-output turn does not mark the session (hung WS / cross-session retry)', () => {
+      const sid = 'codex-sid-zero-output';
+      // Specimen from issue #44: status 499 after 45m, input billed, no output,
+      // no rollout file on disk — `codex resume` would fail.
+      store.markSessionUsage({ sessionId: sid, isSubagent: false, usage: { input_tokens: 9953, output_tokens: 0 } });
+      assert.deepEqual(store.computeSessionResume(sid, 'openai'), { resumable: false, resumeCommand: null });
+    });
+
     it('hasUsage is monotonic — a later usage-less turn keeps resumability', () => {
       const sid = 'codex-sid-monotonic';
-      store.markSessionUsage({ sessionId: sid, isSubagent: false, usage: { input_tokens: 5 } });
+      store.markSessionUsage({ sessionId: sid, isSubagent: false, usage: { input_tokens: 5, output_tokens: 3 } });
       store.markSessionUsage({ sessionId: sid, isSubagent: false, usage: null });
       assert.equal(store.computeSessionResume(sid, 'openai').resumable, true);
     });
 
     it('sentinel sessions are never resumable regardless of provider', () => {
       for (const sid of ['direct-api', 'codex-raw', 'unknown']) {
-        store.markSessionUsage({ sessionId: sid, isSubagent: false, usage: { input_tokens: 5 } });
+        store.markSessionUsage({ sessionId: sid, isSubagent: false, usage: { input_tokens: 5, output_tokens: 3 } });
         assert.deepEqual(store.computeSessionResume(sid, 'openai'), { resumable: false, resumeCommand: null });
         assert.deepEqual(store.computeSessionResume(sid, 'anthropic'), { resumable: false, resumeCommand: null });
       }