feat(tracing): honor SGP_OBS_CORRELATE_BUSINESS at the Correlator construction

Pass the flag into the sgp_obs Correlator that _begin_obs builds for every
adk business span, so the opt-out actually takes effect on the primary
correlation path. Behavior lives in sgp_obs (scaleapi#158071); this is the
construction pass-through.

Version-resilient (_build_correlator): an installed sgp_obs that predates the
`correlate_business` parameter raises TypeError on the kwarg, so we fall back to
the no-arg form and correlation stays always-on rather than dying. The flag
takes effect once the sgp-obs pin is bumped to the release that wired it
(0.5.0). Confirmed against the currently-pinned 0.3.0: fallback, no crash.

Test: env parsing + no-crash fallback + (when supported) the flag reaching the
Correlator instance.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: NiteshDhanpal

src/agentex/lib/core/tracing/trace.py

@@ -49,6 +49,26 @@ def _obs_mode() -> ObsMode:
     return ObsMode.OTEL if (os.getenv("SGP_OBS_MODE") or "").strip().lower() == "lgtm" else ObsMode.DD_ONLY
 
 
+def _correlate_business() -> bool:
+    """``SGP_OBS_CORRELATE_BUSINESS`` — default True. Read from the env directly
+    (mirroring ``_obs_mode``) rather than sgp_obs.TracingConfig, so we don't depend
+    on a specific config-field surface. When false, the Correlator opens the obs
+    span but writes NO business<->obs correlation in either direction."""
+    return (os.getenv("SGP_OBS_CORRELATE_BUSINESS") or "true").strip().lower() not in ("false", "0", "no")
+
+
+def _build_correlator() -> Correlator:
+    """Construct the Correlator, honoring SGP_OBS_CORRELATE_BUSINESS when the
+    installed sgp_obs supports it. Version-resilient: an sgp_obs that predates the
+    ``correlate_business`` parameter raises TypeError on the kwarg — fall back to
+    the no-arg form so correlation keeps working (always-on) instead of dying. The
+    flag takes effect once sgp_obs is bumped to the release that wired it."""
+    try:
+        return Correlator(_OTEL, _DDTRACE, _obs_mode(), correlate_business=_correlate_business())
+    except TypeError:  # sgp_obs predates the flag; correlation stays always-on
+        return Correlator(_OTEL, _DDTRACE, _obs_mode())
+
+
 def _close_obs(handle: ObsSpanHandle | None, error: dict[str, str] | None = None) -> None:
     """Close a wrapper span (best-effort), marking it errored when the business span
     carried an error. Safe on ``None``; obs must never fail the app path."""
@@ -159,7 +179,7 @@ def _begin_obs(
         is_dispatch_boundary=_sgp_temporal.in_dispatch_boundary(),
     )
     try:
-        handle, edge = Correlator(_OTEL, _DDTRACE, _obs_mode()).begin(req)
+        handle, edge = _build_correlator().begin(req)
     except Exception:  # pragma: no cover - obs must never break the business span
         return None, {}
     return handle, edge.as_metadata()

tests/test_correlate_business_passthrough.py

@@ -0,0 +1,40 @@
+"""SDK side of SGP_OBS_CORRELATE_BUSINESS: trace.py reads the env flag and passes
+it into the sgp_obs Correlator, version-resiliently.
+
+The gate BEHAVIOR lives in sgp_obs (Correlator + bridge); here we only prove the
+SDK's construction pass-through: the env is parsed correctly and _build_correlator
+never crashes even when the installed sgp_obs predates the parameter."""
+
+import inspect
+
+from agentex.lib.core.tracing.trace import _build_correlator, _correlate_business
+from sgp_obs.traces.correlator import Correlator
+
+
+def test_correlate_business_env_parsing(monkeypatch):
+    monkeypatch.delenv("SGP_OBS_CORRELATE_BUSINESS", raising=False)
+    assert _correlate_business() is True  # default on
+    for falsey in ("false", "0", "no", "FALSE", " no "):
+        monkeypatch.setenv("SGP_OBS_CORRELATE_BUSINESS", falsey)
+        assert _correlate_business() is False
+    for truthy in ("true", "1", "yes", "", "anything"):
+        monkeypatch.setenv("SGP_OBS_CORRELATE_BUSINESS", truthy)
+        assert _correlate_business() is True
+
+
+def test_build_correlator_never_crashes():
+    # Works whether or not the installed sgp_obs accepts the kwarg (version skew):
+    # with the param -> honored; without -> TypeError fallback to no-arg form.
+    assert isinstance(_build_correlator(), Correlator)
+
+
+def test_build_correlator_passes_flag_when_supported(monkeypatch):
+    supported = "correlate_business" in inspect.signature(Correlator.__init__).parameters
+    if not supported:
+        # Pinned sgp_obs predates the flag; nothing to assert beyond no-crash.
+        assert isinstance(_build_correlator(), Correlator)
+        return
+    monkeypatch.setenv("SGP_OBS_CORRELATE_BUSINESS", "false")
+    corr = _build_correlator()
+    # the flag reached the Correlator instance
+    assert getattr(corr, "_correlate_business") is False