fix(combo): restrict the #6216 empty-stream failover to truly empty bodies (restores #3399/#3685 contracts)

The 'streaming no recognized content' branch added by #6216 marked ANY
stream that ended without content deltas as invalid — sweeping in two
regression-guarded pass-through contracts: an empty stream terminated by an
explicit 'data: [DONE]' (#3399 context-cache protection) and an incomplete
Claude lifecycle (ping only, no message_start; #3685 — stream-readiness
timeout territory, not failover). Both unit guards were red on the branch
and green on main (86/86 vs 84/86).

The branch now fires only for a truly EMPTY body (zero bytes — the Gemini
HTTP-200-empty case that motivated #6216), tracked via sawAnyBytes. New
guard: '#5976 truly EMPTY streaming body (zero bytes) -> invalid for combo
failover'. 87/87 across both files.

Also in this pre-flight batch:
- agentSkillTools-mcp: api.have upper bound 22 -> 23 (the #6186 catalog
  addition updated the totals but missed this bound)
- delete tests/unit/free-provider-rankings-configured-filter.test.ts:
  #6251 (server-side configuredOnly/availableOnly) superseded the #6245
  client-side toggle it pinned; replacement declared in the test-masking
  allowlist (tests/unit/freeProviderRankings-filters.test.ts, 11/11)

config/quality/test-masking-allowlist.json

@@ -25,6 +25,10 @@
     "src/shared/components/AutoRoutingBanner.test.tsx": {
       "replacement": "tests/unit/home-no-autorouting-banner.test.ts",
       "reason": "v3.8.45 #6164: fix(dashboard) remove the always-on Auto-Routing banner — o COMPONENTE foi deletado junto com o teste (feature removida pelo mantenedor, não mascaramento). O replacement guarda o novo contrato: a home NÃO renderiza o banner e o componente permanece deletado."
+    },
+    "tests/unit/free-provider-rankings-configured-filter.test.ts": {
+      "replacement": "tests/unit/freeProviderRankings-filters.test.ts",
+      "reason": "v3.8.45 #6251 supersede #6245: a página Free Provider Rankings migrou do toggle client-side 'Configured Only' (#6245, configuredProviderIds no cliente) para filtros server-side configuredOnly/availableOnly (#6251). O teste antigo pinava a implementação removida (7 asserts quebrados contra código que não existe); o replacement cobre o contrato novo com 11 casos (server-side, lib helper). Verificado legítimo — supersessão documentada no CHANGELOG do #6251."
     }
   },
   "tests/unit/catalog-updates-v3x.test.ts": "v3.8.45 #6248: fix(providers) remove deprecated MiMo V2 entries — os 5 asserts removidos pinavam specs de modelos mimo-v2-* que deixaram de existir no catálogo (54→49). Asserts seguem a remoção dos modelos, não enfraquecimento. Verificado legítimo. Prune após v3.8.45 mergear para main.",

open-sse/services/combo/validateQuality.ts

@@ -97,6 +97,7 @@ export async function validateResponseQuality(
     let hasContentBlock = false;
     let hasLifecycleEnd = false;
     let anyContentFound = false;
+    let sawAnyBytes = false;
     const sseLineNormalizer = createSSEDataLineNormalizer();
     let pendingEventType = "";
 
@@ -234,11 +235,13 @@ export async function validateResponseQuality(
             return { valid: false, reason: "streaming empty content block" };
           }
 
-          // Non-Claude stream with no recognizable content at all — the stream
-          // ended without any content deltas (e.g. Gemini returning HTTP 200
-          // with an empty body or only metadata chunks). Mark as invalid for
-          // combo failover so the sibling model gets tried.
-          if (!anyContentFound && !hasContentBlock) {
+          // Stream ended with a truly EMPTY body (e.g. Gemini returning HTTP
+          // 200 with zero bytes) — mark as invalid for combo failover so the
+          // sibling model gets tried. Streams that carried ANY SSE activity
+          // (an explicit `data: [DONE]`, ping/metadata events, an incomplete
+          // Claude lifecycle) keep the pass-through contract (#3399/#3685):
+          // those are handled by the stream-readiness timeout, not failover.
+          if (!anyContentFound && !hasContentBlock && !sawAnyBytes) {
             log.warn?.(
               "COMBO",
               "Streaming response ended with no recognized content — marking as invalid for combo failover"
@@ -255,6 +258,7 @@ export async function validateResponseQuality(
 
         // Accumulate raw bytes for potential replay.
         bufferedChunks.push(value);
+        if (value && value.length > 0) sawAnyBytes = true;
 
         // Decode incrementally (stream:true keeps multi-byte char state).
         decodedSoFar += decoder.decode(value, { stream: true });

tests/unit/agentSkillTools-mcp.test.ts

@@ -43,8 +43,14 @@ test("agentSkillTools exports exactly 3 tools", () => {
 
 test("each agentSkillTool has name, description, inputSchema, and handler", () => {
   for (const toolDef of Object.values(agentSkillTools)) {
-    assert.ok(typeof toolDef.name === "string" && toolDef.name.length > 0, `${toolDef.name}: name missing`);
-    assert.ok(typeof toolDef.description === "string" && toolDef.description.length > 0, `${toolDef.name}: description missing`);
+    assert.ok(
+      typeof toolDef.name === "string" && toolDef.name.length > 0,
+      `${toolDef.name}: name missing`
+    );
+    assert.ok(
+      typeof toolDef.description === "string" && toolDef.description.length > 0,
+      `${toolDef.name}: description missing`
+    );
     assert.ok(toolDef.inputSchema != null, `${toolDef.name}: inputSchema missing`);
     assert.ok(typeof toolDef.handler === "function", `${toolDef.name}: handler missing`);
   }
@@ -165,7 +171,7 @@ test("omniroute_agent_skills_coverage({}) returns coverage shape", async () => {
   assert.equal(result.cli.total, 20);
   assert.ok(typeof result.api.have === "number");
   assert.ok(typeof result.cli.have === "number");
-  assert.ok(result.api.have >= 0 && result.api.have <= 22);
+  assert.ok(result.api.have >= 0 && result.api.have <= 23);
   assert.ok(result.cli.have >= 0 && result.cli.have <= 20);
   assert.ok(typeof result.totalSkills === "number");
   assert.equal(result.totalSkills, result.api.have + result.cli.have + (result.config?.have ?? 0));

tests/unit/combo-streaming-empty-content-failover.test.ts

@@ -273,3 +273,22 @@ test("#3685 streaming is preserved for non-empty response: clonedResponse body y
   assert.ok(decoded.includes("Hello"), "decoded body must contain the actual text content");
   assert.ok(decoded.includes(", world!"), "decoded body must contain the full text delta");
 });
+
+test("#5976 truly EMPTY streaming body (zero bytes) → invalid for combo failover", async () => {
+  // A 200 SSE response whose body closes without emitting a single byte
+  // (e.g. Gemini returning HTTP 200 with an empty body) cannot carry content —
+  // fail over to the sibling model. Streams with ANY SSE activity (an explicit
+  // [DONE], ping/metadata events) keep the pass-through contract (#3399/#3685).
+  const emptyBody = new ReadableStream<Uint8Array>({
+    start(controller) {
+      controller.close();
+    },
+  });
+  const res = new Response(emptyBody, {
+    status: 200,
+    headers: { "content-type": "text/event-stream" },
+  });
+  const out = await validateResponseQuality(res, true, silentLog);
+  assert.equal(out.valid, false, "zero-byte streaming body must trigger failover");
+  assert.equal(out.reason, "streaming no recognized content");
+});

tests/unit/free-provider-rankings-configured-filter.test.ts

@@ -1,93 +0,0 @@
-/**
- * Unit tests for the "Configured Only" filter on the Free Provider Rankings page.
- *
- * Phase 1 of #6150 — verifies the toggle state, filtering logic, status column,
- * cleanup flag, and i18n keys exist in the source code.
- */
-
-import test from "node:test";
-import assert from "node:assert/strict";
-import { readFileSync } from "node:fs";
-import { join } from "node:path";
-
-const root = join(import.meta.dirname, "../..");
-const read = (p: string) => readFileSync(join(root, p), "utf8");
-const pageSrc = read("src/app/(dashboard)/dashboard/free-provider-rankings/page.tsx");
-const en = JSON.parse(read("src/i18n/messages/en.json"));
-
-test("page declares configuredOnly state", () => {
-  assert.ok(pageSrc.includes("useState(false)"), "configuredOnly defaults to false");
-  assert.ok(pageSrc.includes("setConfiguredOnly"), "setConfiguredOnly setter exists");
-});
-
-test("page declares configuredProviderIds state", () => {
-  assert.ok(pageSrc.includes("configuredProviderIds"), "configuredProviderIds state exists");
-  assert.ok(pageSrc.includes("Set<string>"), "configuredProviderIds is typed as Set<string>");
-});
-
-test("page fetches /api/providers on mount", () => {
-  assert.ok(pageSrc.includes('fetch("/api/providers")'), "fetches /api/providers");
-  assert.ok(pageSrc.includes("conn?.provider"), "uses optional chaining for conn.provider");
-});
-
-test("useEffect has cleanup flag to prevent stale state updates", () => {
-  assert.ok(pageSrc.includes("let active = true"), "declares cleanup flag");
-  assert.ok(pageSrc.includes("if (!active) return"), "guards state update with active flag");
-  assert.ok(pageSrc.includes("active = false"), "cleanup function sets active to false");
-});
-
-test("displayedRankings filters by configuredProviderIds when toggle is on", () => {
-  assert.ok(pageSrc.includes("displayedRankings"), "displayedRankings derived variable exists");
-  assert.ok(
-    pageSrc.includes("configuredProviderIds.has(r.id)"),
-    "filters rankings by configuredProviderIds.has(r.id)"
-  );
-  assert.ok(
-    pageSrc.includes("configuredOnly\n    ? rankings.filter"),
-    "conditional: when configuredOnly is true, filters rankings"
-  );
-});
-
-test("toggle switch has accessible attributes", () => {
-  assert.ok(pageSrc.includes('role="switch"'), "toggle has role=switch");
-  assert.ok(
-    pageSrc.includes("aria-checked={configuredOnly}"),
-    "toggle has aria-checked bound to configuredOnly"
-  );
-  assert.ok(
-    pageSrc.includes('htmlFor="configured-only-toggle"'),
-    "label is linked to toggle via htmlFor"
-  );
-});
-
-test("table has a 'Configured' status column", () => {
-  assert.ok(pageSrc.includes('t("colConfigured")'), "table header includes colConfigured key");
-  assert.ok(
-    pageSrc.includes("configuredProviderIds.has(provider.id)"),
-    "status column checks configuredProviderIds"
-  );
-});
-
-test("empty state shows noConfiguredProviders when toggle is on", () => {
-  assert.ok(
-    pageSrc.includes('t("noConfiguredProviders")'),
-    "empty state uses noConfiguredProviders i18n key"
-  );
-  assert.ok(
-    pageSrc.includes("configuredOnly && rankings.length > 0"),
-    "shows noConfiguredProviders only when toggle is on and data exists"
-  );
-});
-
-test("i18n: en.json has all required filter keys", () => {
-  const keys = en.freeProviderRankingsPage;
-  assert.ok(keys, "freeProviderRankingsPage namespace exists in en.json");
-  assert.equal(typeof keys.configuredOnly, "string", "configuredOnly is a string");
-  assert.equal(typeof keys.configuredOnlyHint, "string", "configuredOnlyHint is a string");
-  assert.equal(typeof keys.noConfiguredProviders, "string", "noConfiguredProviders is a string");
-  assert.equal(typeof keys.colConfigured, "string", "colConfigured is a string");
-  assert.ok(keys.configuredOnly.length > 0, "configuredOnly is non-empty");
-  assert.ok(keys.configuredOnlyHint.length > 0, "configuredOnlyHint is non-empty");
-  assert.ok(keys.noConfiguredProviders.length > 0, "noConfiguredProviders is non-empty");
-  assert.ok(keys.colConfigured.length > 0, "colConfigured is non-empty");
-});