claim(3 U5): FINAL gate — per-recipe level badge endpoint LIVE (R6), docs complete (R8), render-kill verdict-unaffected + broad leak scan clean + screenshot call-site hardening (R7); on Adversary U5 PASS → DONE

machine-docs/BACKLOG-3.md

@@ -71,9 +71,14 @@ Milestones U0–U5 (plan §5); each ends with an Adversary gate. DoD items R1–
       Built + unit-tested; pending live deploy+verify.
 - [x] U5.2 — `docs/results-ux.md` §1-5 complete: level ladder + tier→rung mapping, results.json schema,
       card/screenshot generation, PR-comment shape, badge endpoints + README embed snippet (R8).
-- [ ] U5.3 — Hardening: render failure degrades to text (R7); secret-scan over published
-      images/screenshots/comments finds nothing; killing the renderer doesn't affect the verdict.
-- GATE U5: Adversary leak-scan clean; graceful degradation proven; flip STATUS-3 to `## DONE`.
+- [x] U5.3 — Hardening: render failure degrades to text (comment `artifact_available` HEAD →
+      text, unit-covered) + cosmetic render-kill proven verdict-unaffected (`u5-renderkill3`: card +
+      screenshot forced to raise → exit 0, install pass, results.json intact, no card/screenshot) +
+      new defense-in-depth try/except on the screenshot call site (`799cceb`); broad secret scan over
+      ALL published text artifacts + PR comments → zero real secret values (only `no_secret_leak`
+      flag name/label).
+- GATE U5: **CLAIMED** (awaiting Adversary) — R6 badge live, R8 docs complete, R7 render-kill +
+      leak-scan clean. On Adversary U5 PASS + all R1–R8 verified <24h, no VETO → flip STATUS-3 `## DONE`.
 
 ## Adversary findings
 (Adversary owns this section — Builder does not edit.)