fix(compression): repair the unit-test base-reds left by the 09-17 merge wave (#14082)

Every PR against release/v3.8.51 is born red on all four Unit Tests fast-path
shards. Reproduced on the pure tip (1603c86e): ~35 tests. This commit repairs
the two large clusters plus the stale assertions sharing their root cause
(17 tests); the rest is tracked separately.

RTK (12 tests, real regression): #13521 gated dedup on
  skipFilters || isDocumentLikeRead
but isDocumentLikeRead is true for ANY text whose type detection is unknown —
not only non-shell tool results — so plain repeated tool output (the classic
RTK case) stopped being deduplicated, processRtkText returned no stats, and
rtkEngine.apply().stats.engine came back undefined. The intent of #13388 was
the non-shell-tool skip, which resolveToolMeta already expresses as
skipFilters; dedup now honours only that. The #13521 regression guard
(rtk-file-content-preservation, tool named 'read' → skipFilters) still passes
4/4; rtk-engine is back to 9/9.

Golden + stale assertions (5 tests, product changes never propagated):
- tests/snapshots/provider/translate-path.json: xKiro (#12648) was added to the
  registry without regenerating the snapshot — purely additive entry.
- providers-constants-split: APIKEY_PROVIDER_COUNT 241 → 242 (xKiro).
- tests/snapshots/g13/combo-chatcore-public-seams.json and the three
  Content-Type assertions in chatcore-translation-paths / chat-route-coverage:
  #13419 deliberately made streaming responses declare
  'text/event-stream; charset=utf-8' (Arabic/Persian mojibake) and updated the
  integration test but not these unit assertions.

Before/after on the 26 base-red files: 266 tests, 23 → 18 failing here
(the RTK suites were counted per-file in CI; per-test this is 17 fixed). The
file-size ✗ on chatcore-translation-paths.test.ts is the pre-existing drift
#14016 rebaselines — this commit keeps that file's line count unchanged.

changelog.d/maintenance/release-v3851-basereds-unit-rtk-golden.md

@@ -0,0 +1 @@
+- **compression/tests:** repair the unit base-reds on `release/v3.8.51` left by the 09-17 merge wave — RTK dedup was skipped for every unknown-type text (#13521 widened `skipFilters` to `isDocumentLikeRead`), so repeated tool output stopped compressing (12 tests); the translate-path golden, the `APIKEY_PROVIDERS` count and the G13 golden/SSE `Content-Type` assertions were stale after #12648 (xKiro) and #13419 (`charset=utf-8`).

open-sse/services/compression/engines/rtk/index.ts

@@ -314,7 +314,7 @@ export function processRtkText(
   // #13388: skip dedup for non-shell tool results (file reads, grep, glob, etc.)
   // where repeated structural lines are semantically meaningful. Also skip when
   // the content is a document-like read to avoid false-positive dedup on code files.
-  const shouldSkipDedup = options.skipFilters || isDocumentLikeRead;
+  const shouldSkipDedup = Boolean(options.skipFilters);
   const deduped = shouldSkipDedup
     ? { text: result, collapsed: 0 }
     : deduplicateRepeatedLines(result, { threshold: config.deduplicateThreshold });

tests/snapshots/g13/combo-chatcore-public-seams.json

@@ -392,7 +392,7 @@
         "output": {
           "Cache-Control": "no-cache, no-transform",
           "Connection": "keep-alive",
-          "Content-Type": "text/event-stream",
+          "Content-Type": "text/event-stream; charset=utf-8",
           "X-Accel-Buffering": "no",
           "X-OmniRoute-Cache": "MISS",
           "X-OmniRoute-Cache-Hit": "false",
@@ -416,7 +416,7 @@
         "output": {
           "Cache-Control": "no-cache, no-transform",
           "Connection": "keep-alive",
-          "Content-Type": "text/event-stream",
+          "Content-Type": "text/event-stream; charset=utf-8",
           "X-Accel-Buffering": "no",
           "X-OmniRoute-Cache": "MISS",
           "X-OmniRoute-Cache-Hit": "false",

tests/snapshots/provider/translate-path.json

@@ -6398,6 +6398,29 @@
       "stream": "https://token-plan-sgp.xiaomimimo.com/v1"
     }
   },
+  "xkiro": {
+    "format": "openai",
+    "headers": {
+      "apiKey": {
+        "Accept": "text/event-stream",
+        "Authorization": "Bearer <TOK>",
+        "Content-Type": "application/json"
+      },
+      "nonStream": {
+        "Authorization": "Bearer <TOK>",
+        "Content-Type": "application/json"
+      },
+      "oauth": {
+        "Accept": "text/event-stream",
+        "Authorization": "Bearer <TOK>",
+        "Content-Type": "application/json"
+      }
+    },
+    "url": {
+      "nonStream": "https://api.xkiro.com/v1/chat/completions",
+      "stream": "https://api.xkiro.com/v1/chat/completions"
+    }
+  },
   "yi": {
     "format": "openai",
     "headers": {

tests/unit/chat-route-coverage.test.ts

@@ -157,7 +157,7 @@ test("handleChat treats a pure Accept: text/event-stream as stream=true and retu
 
   const raw = await response.text();
   assert.equal(response.status, 200);
-  assert.equal(response.headers.get("Content-Type"), "text/event-stream");
+  assert.equal(response.headers.get("Content-Type"), "text/event-stream; charset=utf-8");
   assert.ok(response.headers.get("X-OmniRoute-Session-Id"));
   assert.match(raw, /Accept header stream/);
   assert.match(raw, /\[DONE\]/);

tests/unit/chatcore-translation-paths.test.ts

@@ -2993,7 +2993,7 @@ test("buildStreamingResponseHeaders drops upstream compression and framing heade
     )
   );
 
-  assert.equal(headers.get("Content-Type"), "text/event-stream");
+  assert.equal(headers.get("Content-Type"), "text/event-stream; charset=utf-8");
   assert.equal(headers.get("Content-Encoding"), null);
   assert.equal(headers.get("Content-Length"), null);
   assert.equal(headers.get("Transfer-Encoding"), null);
@@ -3028,7 +3028,7 @@ test("chatCore strips upstream compression and length headers from streaming res
   });
 
   assert.equal(result.success, true);
-  assert.equal(result.response.headers.get("Content-Type"), "text/event-stream");
+  assert.equal(result.response.headers.get("Content-Type"), "text/event-stream; charset=utf-8");
   assert.equal(result.response.headers.get("Content-Length"), null);
   assert.equal(result.response.headers.get("X-Upstream-Trace"), "trace-1");
   assert.equal(result.response.headers.get("X-OmniRoute-Cache"), "MISS");

tests/unit/providers-constants-split.test.ts

@@ -36,12 +36,13 @@
 // SeekAi (#11786, QuantumNous New-API gateway) adds one gateways entry — 238.
 // GreenPT (#13024, 2b9e7fb3e) and EURouter (#13025, 22473dee5) each add one gateways entry — 240.
 // Agnes AI China (#13399, cdcde97c7) adds one apikey/regional entry — 241.
+// xKiro (#12648, 83fa4328f) adds one apikey entry — 242.
 import { test } from "node:test";
 import assert from "node:assert/strict";
 
 const P = await import("../../src/shared/constants/providers.ts");
 
-const APIKEY_PROVIDER_COUNT = 241;
+const APIKEY_PROVIDER_COUNT = 242;
 
 test("barrel still exports every catalog + key helpers", () => {
   for (const name of [