fix(translate): handle invalid LLM JSON responses

shared/src/ss_tools/shared/_llm_http.py

@@ -19,6 +19,7 @@
 #   Only capath-based ssl.create_default_context() works with OpenSSL 3.x intermediates.
 
 import asyncio
+import json
 import ssl
 from typing import Any
 
@@ -115,7 +116,12 @@ def sanitize_url(url: str) -> str:
 # @BRIEF Call OpenAI-compatible API asynchronously with rate-limit handling and structured output fallback.
 # @PRE Valid API endpoint, key, model, and prompt.
 # @POST Returns (response text, finish_reason).
+# @RAISES ValueError when the provider returns an invalid JSON response body.
 # @SIDE_EFFECT Async HTTP POST to LLM API with optional retry on 429.
+# @RATIONALE Normalize malformed successful HTTP bodies into a stable provider error so
+#   preview and execution callers do not leak raw JSONDecodeError details.
+# @REJECTED Letting response.json() propagate raw decode failures was rejected — it
+#   obscures the upstream failure and prevents callers from classifying the provider error.
 # @REJECTED Keeping sync requests.post — would block async event loop during LLM calls.
 #   Per-request httpx.AsyncClient — loses connection pooling.
 async def call_openai_compatible(
@@ -177,7 +183,20 @@ async def call_openai_compatible(
             extra={"src": "SharedLlmHttpClient"},
         )
     response.raise_for_status()
-    data = response.json()
+    try:
+        data = response.json()
+    except (json.JSONDecodeError, ValueError) as exc:
+        logger.explore(
+            "LLM provider returned an invalid JSON response",
+            extra={
+                "src": "SharedLlmHttpClient",
+                "status_code": response.status_code,
+                "content_type": response.headers.get("content-type"),
+                "response_preview": (response_text or "")[:2000],
+            },
+            error=f"{type(exc).__name__}: {exc}",
+        )
+        raise ValueError("LLM provider returned an invalid JSON response") from exc
 
     choices = data.get("choices", [])
     if not choices: