fix: harden partial 429 success, fallbacks, zh errors

Retry HTTP 429 with backoff; keep models beyond first 3 as
fallbacks; degrade agreement when some models fail; force-high
risk only if zero usable responses. Clearer zh-CN errors/docs for
dogfood uses: ./ rebase + workflow_dispatch re-run.

scripts/merge-findings.js

@@ -167,10 +167,22 @@ for (const m of models) {
   }
 }
 
+// Prefer successful model tiers; only if every call failed, fail-closed high.
+const okModels = models.filter((m) => !m.error);
+const modelErrors = models.filter((m) => m.error).length;
+const degraded = modelErrors > 0 || okModels.length < agreementMin;
+
+// When some models 429/fail, lower the bar to surface usable findings from survivors
+// (still require at least 1 successful model). Full fail-closed high only if zero ok.
+let effectiveAgreement = agreementMin;
+if (okModels.length > 0 && okModels.length < agreementMin) {
+  effectiveAgreement = Math.max(1, okModels.length);
+}
+
 const agreed = [];
 const disputed = [];
 for (const f of bucket.values()) {
-  if (f.models.length >= agreementMin) agreed.push(f);
+  if (f.models.length >= effectiveAgreement) agreed.push(f);
   else disputed.push(f);
 }
 
@@ -178,8 +190,6 @@ const bySeverity = (a, b) => (sevRank[a.severity] ?? 9) - (sevRank[b.severity] ?
 agreed.sort(bySeverity);
 disputed.sort(bySeverity);
 
-// Prefer successful model tiers; only if every call failed, fail-closed high.
-const okModels = models.filter((m) => !m.error);
 const tierSources = okModels.length ? okModels : models;
 let risk_tier = floor;
 for (const m of tierSources) risk_tier = maxTier(risk_tier, m.risk_tier);
@@ -193,13 +203,13 @@ if (scanHardFail) risk_tier = maxTier(risk_tier, "high");
 const openSecurityBlocking =
   scanHardFail || agreed.some((f) => (f.kind === "security" || f.severity === "Critical") && f.blocking);
 
-const modelErrors = models.filter((m) => m.error).length;
-
 const result = {
   risk_tier,
   policy_floor: floor,
   agreement_min: agreementMin,
+  effective_agreement_min: effectiveAgreement,
   language,
+  degraded,
   model_errors: modelErrors,
   models_ok: okModels.length,
   models: models.map((m) => ({