test(cdp): expect Base64 for intercepted text response bodies

moli-cdp-smoke/README.md

@@ -25,6 +25,16 @@ observed, but it does not replace the executable probe when one can be run. If
 Chromium cannot be tested, document that limitation explicitly instead of
 presenting an inferred expectation as verified behavior.
 
+The `Fetch.getResponseBody` text encoding was calibrated on 2026-10-19 against
+Debian `/usr/bin/chromium` 145.0.7632.116. A fresh page enabled `Network` and
+`Fetch` with `requestStage: "Response"`, navigated to a local UTF-8 HTML fixture,
+and read its paused body before continuing the response. Chromium returned
+Base64 with `base64Encoded: true`; reading the completed request through
+`Network.getResponseBody` returned the original text with `base64Encoded: false`.
+The `network` and `multi-context` groups require the encoded Fetch body and flag,
+then independently verify the original page-visible text after continuation.
+Their Network body and `IO.read` stream assertions retain their own contracts.
+
 The default `cdp-ordering` group locks down Renderer native and Inspector wire
 publication order. It pipelines Page trees/layout, DOMSnapshot, DOM queries and
 objects, CSS, AX, and a native backend error before `Runtime.enable`; stylesheet

moli-cdp-smoke/moli_cdp_smoke/groups/multi_context.py

@@ -644,10 +644,10 @@ async def run_multi_context_popup_response_stage_body_owner_state_smoke(
 
         body_a = await _send_cdp(cdp_a, "Fetch.getResponseBody", {"requestId": request_id_a})
         body_b = await _send_cdp(cdp_b, "Fetch.getResponseBody", {"requestId": request_id_b})
-        assert_equal(body_a.get("body"), "response-stage body", "context A popup Fetch.getResponseBody")
-        assert_equal(body_b.get("body"), "response-stage body", "context B popup Fetch.getResponseBody")
-        assert_equal(body_a.get("base64Encoded"), False, "context A popup Fetch.getResponseBody encoding")
-        assert_equal(body_b.get("base64Encoded"), False, "context B popup Fetch.getResponseBody encoding")
+        assert_equal(body_a.get("body"), RESPONSE_STAGE_BODY_BASE64, "context A popup Fetch.getResponseBody")
+        assert_equal(body_b.get("body"), RESPONSE_STAGE_BODY_BASE64, "context B popup Fetch.getResponseBody")
+        assert_equal(body_a.get("base64Encoded"), True, "context A popup Fetch.getResponseBody encoding")
+        assert_equal(body_b.get("base64Encoded"), True, "context B popup Fetch.getResponseBody encoding")
 
         if fetch_a.done() or fetch_b.done():
             raise SmokeError("popup response-stage fetch completed before continueResponse")

moli-cdp-smoke/moli_cdp_smoke/groups/network.py

@@ -828,8 +828,12 @@ async def _verify_response_stage_xhr_get_response_body(state: SmokeState) -> Non
             raise SmokeError(f"missing response-stage XHR networkId: {paused}")
 
         body = await state.cdp.send("Fetch.getResponseBody", {"requestId": request_id})
-        assert_equal(body.get("body"), "response-stage body", "XHR response-stage Fetch.getResponseBody body")
-        assert_equal(body.get("base64Encoded"), False, "XHR response-stage Fetch.getResponseBody encoding")
+        assert_equal(
+            body.get("body"),
+            base64.b64encode(b"response-stage body").decode("ascii"),
+            "XHR response-stage Fetch.getResponseBody body",
+        )
+        assert_equal(body.get("base64Encoded"), True, "XHR response-stage Fetch.getResponseBody encoding")
 
         await state.cdp.send("Fetch.continueResponse", {"requestId": request_id})
         await wait_until(
@@ -1613,8 +1617,12 @@ async def _verify_fetch_auth_response_stage(state: SmokeState) -> None:
         )
 
         body_result = await state.cdp.send("Fetch.getResponseBody", {"requestId": request_id})
-        assert_equal(body_result.get("base64Encoded"), False, "Fetch auth response-stage body encoding")
-        assert_equal(body_result.get("body"), "authenticated fetch", "Fetch auth response-stage paused body")
+        assert_equal(body_result.get("base64Encoded"), True, "Fetch auth response-stage body encoding")
+        assert_equal(
+            body_result.get("body"),
+            base64.b64encode(b"authenticated fetch").decode("ascii"),
+            "Fetch auth response-stage paused body",
+        )
 
         await state.cdp.send("Fetch.continueResponse", {"requestId": request_id})
         await wait_until(