diff --git a/skyvern/forge/failure_classifier.py b/skyvern/forge/failure_classifier.py
index 1cdc63af6..922be3e06 100644
--- a/skyvern/forge/failure_classifier.py
+++ b/skyvern/forge/failure_classifier.py
@@ -1,5 +1,12 @@
 from __future__ import annotations
 
+import re
+
+# Matches the activity/heartbeat timeout tokens the worker persists when a Temporal-activity
+# timeout finalizes a run. Word-anchored so "inactivity timeout" (a distinct page-level reason)
+# is NOT caught and correctly stays PAGE_LOAD_TIMEOUT.
+_INFRA_TIMEOUT_RE = re.compile(r"\b(?:activity|heartbeat) timeout\b")
+
 
 def classify_from_failure_reason(
     failure_reason: str | None,
@@ -102,8 +109,21 @@ def classify_from_failure_reason(
             }
         )
 
+    # Infrastructure timeout — a Temporal activity / heartbeat timeout finalizes the run from
+    # the worker layer (a stalled activity or worker interruption), not a site/page-load issue.
+    # Classify before PAGE_LOAD_TIMEOUT so these don't masquerade as site slowness.
+    _is_infra_timeout = bool(_INFRA_TIMEOUT_RE.search(reason))
+    if _is_infra_timeout:
+        categories.append(
+            {
+                "category": "INFRASTRUCTURE_ERROR",
+                "confidence_float": 0.9,
+                "reasoning": "Activity/heartbeat timeout finalized the run",
+            }
+        )
+
     # Page load timeout
-    if "Timeout" in exc_name or "timeout" in reason:
+    if ("Timeout" in exc_name or "timeout" in reason) and not _is_infra_timeout:
         categories.append(
             {
                 "category": "PAGE_LOAD_TIMEOUT",
diff --git a/tests/unit/test_failure_classifier.py b/tests/unit/test_failure_classifier.py
index 2149d288e..a8ba80b86 100644
--- a/tests/unit/test_failure_classifier.py
+++ b/tests/unit/test_failure_classifier.py
@@ -214,3 +214,37 @@ def test_keyword_match_ignores_fallback() -> None:
     result_without = _classify("browser crash detected", fallback_to_unknown=False)
 
     assert result_with[0]["category"] == result_without[0]["category"] == "BROWSER_ERROR"
+
+
+def test_activity_heartbeat_timeout_classifies_as_infrastructure() -> None:
+    reason = "Workflow run timed out: the workflow activity became unresponsive (activity heartbeat timeout)."
+    categories = _categories_for(reason)
+
+    assert categories[0] == "INFRASTRUCTURE_ERROR"
+    # An infra-level activity timeout must not masquerade as site/page-load slowness.
+    assert "PAGE_LOAD_TIMEOUT" not in categories
+
+
+def test_generic_activity_timeout_classifies_as_infrastructure() -> None:
+    reason = "Workflow run timed out: the workflow activity became unresponsive (activity timeout)."
+    categories = _categories_for(reason)
+
+    assert categories[0] == "INFRASTRUCTURE_ERROR"
+    assert "PAGE_LOAD_TIMEOUT" not in categories
+
+
+def test_page_load_timeout_still_classifies_without_activity_context() -> None:
+    categories = _categories_for("Navigation timeout while waiting for page load")
+
+    assert "PAGE_LOAD_TIMEOUT" in categories
+    assert "INFRASTRUCTURE_ERROR" not in categories
+
+
+def test_inactivity_timeout_is_not_infrastructure() -> None:
+    # "inactivity timeout" is a session/page-level reason; a naive substring match on
+    # "activity timeout" would wrongly reclassify it as INFRASTRUCTURE_ERROR and drop
+    # PAGE_LOAD_TIMEOUT. The word-anchored match must leave it alone.
+    categories = _categories_for("Session ended: inactivity timeout on the page")
+
+    assert "INFRASTRUCTURE_ERROR" not in categories
+    assert "PAGE_LOAD_TIMEOUT" in categories