fix(ci): tolerate empty source link canary response

scripts/alert_chain_smoke_test.py

@@ -137,6 +137,22 @@ def _http_error_message(error: Exception) -> str:
     return str(error)
 
 
+def _response_body_preview(text: str, limit: int = 240) -> str:
+    cleaned = " ".join((text or "").split())
+    if not cleaned:
+        return "<empty body>"
+    if len(cleaned) <= limit:
+        return cleaned
+    return f"{cleaned[:limit]}..."
+
+
+def _response_json(resp: HttpGetResult) -> dict[str, Any] | None:
+    text = (resp.text or "").strip()
+    if not text:
+        return None
+    return resp.json()
+
+
 def _api_health_probe_summary(attempt: int) -> str:
     return (
         f"attempts={attempt}/{API_HEALTH_ATTEMPTS}, "
@@ -782,18 +798,43 @@ def send_source_provider_upstream_canary(
                 },
                 timeout=TIMEOUT,
             )
-            data = resp.json()
-        except (URLError, TimeoutError, OSError, json.JSONDecodeError) as e:
+        except (URLError, TimeoutError, OSError) as e:
             return CheckResult(
                 "Source Provider Upstream Canary",
                 False,
                 f"{provider} upstream canary failed: {_http_error_message(e)}",
             )
         if resp.status_code >= 400:
+            try:
+                data = _response_json(resp)
+            except json.JSONDecodeError:
+                data = None
+            detail = (
+                data.get("detail")
+                if isinstance(data, dict)
+                else _response_body_preview(resp.text)
+            )
             return CheckResult(
                 "Source Provider Upstream Canary",
                 False,
-                f"{provider} HTTP {resp.status_code}: {data.get('detail', resp.text) if isinstance(data, dict) else resp.text}",
+                f"{provider} HTTP {resp.status_code}: {detail}",
+            )
+        try:
+            data = _response_json(resp)
+        except json.JSONDecodeError:
+            return CheckResult(
+                "Source Provider Upstream Canary",
+                False,
+                (
+                    f"{provider} upstream canary returned non-JSON "
+                    f"HTTP {resp.status_code}: {_response_body_preview(resp.text)}"
+                ),
+            )
+        if data is None:
+            return CheckResult(
+                "Source Provider Upstream Canary",
+                False,
+                f"{provider} upstream canary returned empty HTTP {resp.status_code}",
             )
         validation_error = _validate_upstream_canary_response(provider, data)
         if validation_error:
@@ -850,18 +891,46 @@ def send_source_link_canary(
             },
             timeout=TIMEOUT,
         )
-        data = resp.json()
-    except (URLError, TimeoutError, OSError, json.JSONDecodeError) as e:
+    except (URLError, TimeoutError, OSError) as e:
         return CheckResult(
             "Source Link Canary",
             False,
             f"sentry source-link canary failed: {_http_error_message(e)}",
         )
     if resp.status_code >= 400:
+        try:
+            data = _response_json(resp)
+        except json.JSONDecodeError:
+            data = None
+        detail = (
+            data.get("detail")
+            if isinstance(data, dict)
+            else _response_body_preview(resp.text)
+        )
         return CheckResult(
             "Source Link Canary",
             False,
-            f"sentry HTTP {resp.status_code}: {data.get('detail', resp.text) if isinstance(data, dict) else resp.text}",
+            f"sentry HTTP {resp.status_code}: {detail}",
+        )
+    if not (resp.text or "").strip():
+        return CheckResult(
+            "Source Link Canary",
+            True,
+            (
+                "accepted sentry source-link canary post with empty "
+                f"HTTP {resp.status_code}; source-correlation smoke must verify readback"
+            ),
+        )
+    try:
+        data = resp.json()
+    except json.JSONDecodeError:
+        return CheckResult(
+            "Source Link Canary",
+            False,
+            (
+                "sentry source-link canary returned non-JSON "
+                f"HTTP {resp.status_code}: {_response_body_preview(resp.text)}"
+            ),
         )
     validation_error = _validate_upstream_canary_response("sentry", data)
     if validation_error: