diff --git a/internal/check-poster-print-fallback.mjs b/internal/check-poster-print-fallback.mjs
index 968a13c3a..e2588595c 100644
--- a/internal/check-poster-print-fallback.mjs
+++ b/internal/check-poster-print-fallback.mjs
@@ -124,9 +124,18 @@ page.on('pageerror', (e) => errs.push(String(e).slice(0, 140)))
 // when that generator cannot load (a policy that refuses both the blob and the classic
 // script, a failed integrity check, a print while offline), so the generator is blocked
 // too, and the .html is the one way through.
+// ★ ASSERT THE OUTCOME, NOT THE REQUEST (2026-09-29). A poison run answered 404 to posters/<id>.html
+// for the browser only, and this gate still PASSED: it counted the REQUEST, and its failure pattern did
+// not match what the wall then says ("poster not found (404)"). So it could not fail on the one path it
+// exists for. It now requires the .html to ANSWER 200, a print frame to actually OPEN (counted at
+// creation, the degrade gate's technique), and reads "not found" as the failure it is.
 let webpBlocked = 0
 let htmlServed = 0
+let htmlOk = 0
+let printFrames = 0
 let generatorBlocked = 0
+page.on('response', (r) => { if (/\/posters\/[^/?]+\.html(\?|$)/.test(r.url()) && r.status() === 200) htmlOk += 1 })
+await page.exposeFunction('__notePrintFrame', () => { printFrames += 1 })
 await page.route('**/posters/*.webp', (route) => { webpBlocked += 1; route.abort() })
 await page.route('**/posters/*.html', (route) => { htmlServed += 1; route.continue() })
 await page.route(/\/lib\/poster-render(\.global)?\.js(\?|$)/, (route) => { generatorBlocked += 1; route.abort() })
@@ -147,6 +156,18 @@ await page.waitForTimeout(8000)
 await page.evaluate(() => {
   window.__HUD = []
   window.print = () => {}
+  // Count print frames AT CREATION: the frame self-removes on afterprint, so polling finds none.
+  const realAppend = Node.prototype.appendChild
+  Node.prototype.appendChild = function (n) {
+    const r = realAppend.call(this, n)
+    try {
+      if (n && n.tagName === 'IFRAME') {
+        window.__notePrintFrame()
+        try { n.contentWindow.print = () => {} } catch { /* cross-realm */ }
+      }
+    } catch { /* never break the page to observe it */ }
+    return r
+  }
   const walk = (root, out = []) => {
     for (const el of root.querySelectorAll('*')) { out.push(el); if (el.shadowRoot) walk(el.shadowRoot, out) }
     return out
@@ -154,7 +175,7 @@ await page.evaluate(() => {
   window.__readHud = () => walk(document)
     .filter((e) => e.childElementCount === 0 && e.tagName !== 'SCRIPT' && e.tagName !== 'STYLE')
     .map((e) => (e.textContent || '').trim())
-    .filter((t) => t && /generating|preparing|saving|not available|failed|blank|error/i.test(t))
+    .filter((t) => t && /generating|preparing|saving|not found|not available|failed|blank|error/i.test(t))
   setInterval(() => { for (const t of window.__readHud()) if (!window.__HUD.includes(t)) window.__HUD.push(t) }, 120)
 })
 
@@ -198,7 +219,7 @@ if (clicked.ok) {
     hud = await page.evaluate(() => window.__HUD || [])
     // Terminal states: an explicit failure, or "generating" seen AND no longer showing.
     const live = await page.evaluate(() => window.__readHud())
-    const failing = hud.some((t) => /not available|failed|blank|error/i.test(t))
+    const failing = hud.some((t) => /not found|not available|failed|blank|error/i.test(t))
     const generated = hud.some((t) => /generating/i.test(t))
     if (failing) { settled = true; break }
     if (generated && !live.some((t) => /generating|preparing|saving/i.test(t))) { settled = true }
@@ -219,8 +240,8 @@ if (hud.some((t) => /Poster not available yet/i.test(t))) {
   fails.push('the print preview opened on "Poster not available yet" — the old behaviour: '
     + 'the .webp 404ed and the rasterise fallback did not run')
 }
-if (hud.some((t) => /not available|failed|blank|error/i.test(t))) {
-  fails.push(`the print path ended in an error state: ${JSON.stringify(hud.filter((t) => /not available|failed|blank|error/i.test(t)))}`)
+if (hud.some((t) => /not found|not available|failed|blank|error/i.test(t))) {
+  fails.push(`the print path ended in an error state: ${JSON.stringify(hud.filter((t) => /not found|not available|failed|blank|error/i.test(t)))}`)
 }
 // With EVERY .webp aborted, a clean run is only possible via the rasteriser — so the
 // "generating the poster" phase MUST have been entered. Its absence means the preview
@@ -238,13 +259,20 @@ if (webpBlocked === 0) {
 }
 if (htmlServed === 0) {
   fails.push('no posters/*.html was fetched — the rasterise fallback never ran')
+} else if (htmlOk === 0) {
+  // THE OUTCOME, not the attempt: requested is not loaded, and a 404 source rasterises nothing.
+  fails.push(`posters/*.html was requested ${htmlServed} time(s) but never answered 200 — the fallback had no source to rasterise`)
+}
+if (clicked.ok && printFrames === 0) {
+  fails.push('no print frame opened — the print path never reached the dialog, so nothing was printed')
 }
 if (errs.length) fails.push(`${errs.length} page error(s): ${errs[0]}`)
 
 console.log('POSTER-PRINT-FALLBACK')
 console.log(`  wall            : ${WALL}`)
 console.log(`  .webp requests  : ${webpBlocked} (all aborted — the default-drop condition)`)
-console.log(`  .html requests  : ${htmlServed}`)
+console.log(`  .html requests  : ${htmlServed} (${htmlOk} answered 200)`)
+console.log(`  print frames    : ${printFrames}`)
 console.log(`  generator       : ${generatorBlocked} request(s) aborted${generatorBlocked ? '' : ' (this wall generated nothing first)'}`)
 console.log(`  print button    : ${clicked.ok ? 'found and clicked' : 'NOT FOUND'}`)
 console.log(`  HUD             : ${hud.length ? JSON.stringify(hud) : '(nothing)'}`)