Name the Carried Cause in the COVERAGE_IS_PARTIAL Status Line

scripts/pr_review.py

@@ -189,6 +189,7 @@
 )
 from pr_review_rounds import (
     ACK_MARKER,
+    CARRIED_PARTIAL,
     CODERABBIT_LOGIN,
     FILES_UNREAD,
     KNOWN_REVIEWERS,
@@ -994,12 +995,21 @@ def report_verdict(pr: dict) -> int:
         return 0
     state, why = coverage(pr)
     if state == "partial":
-        print(
-            f"status=COVERAGE_IS_PARTIAL the review covering the head states it read fewer files "
-            f"than the pull request changed ({why}), so part of the diff has no review at all. A "
-            "re-request is not the remedy it reads as. Splitting is the remedy where it applies, "
-            "and it does not apply to a promotion. Otherwise this is the maintainer's call"
-        )
+        if why.startswith(CARRIED_PARTIAL):
+            print(
+                f"status=COVERAGE_IS_PARTIAL the head reads as partial because {why}, so part of "
+                "the diff may have no review. A round on the head stating full coverage clears "
+                "this, unless a round on it already states a reading this cannot believe. "
+                "Otherwise this is the maintainer's call"
+            )
+        else:
+            print(
+                f"status=COVERAGE_IS_PARTIAL the review covering the head states it read fewer "
+                f"files than the pull request changed ({why}), so part of the diff has no review "
+                "at all. A re-request is not the remedy it reads as. Splitting is the remedy where "
+                "it applies, and it does not apply to a promotion. Otherwise this is the "
+                "maintainer's call"
+            )
         return 42
     if flagged := uncounted_verdict(pr):
         print(

scripts/pr_review_rounds.py

@@ -31,6 +31,7 @@
 )
 TRUSTED_ASSOCIATIONS = frozenset({"OWNER", "MEMBER", "COLLABORATOR"})
 ACK_MARKER = "<!-- fleet-shape-ack: fingerprint={} -->"
+CARRIED_PARTIAL = "an earlier round states partial coverage"
 
 
 def reviewer_requested(pr: dict) -> bool:
@@ -437,7 +438,7 @@ def coverage(pr: dict) -> tuple[str, str]:
             if worst
             else "no round on the head states any"
         )
-        return "partial", f"an earlier round states partial coverage, and {none}"
+        return "partial", f"{CARRIED_PARTIAL}, and {none}"
     if worst:
         return worst
     why = ""

tests/test_pr_review.py

@@ -1989,12 +1989,27 @@ def test_a_head_round_stating_partial_coverage_exits_forty_two(self) -> None:
         self.assertEqual(42, self.status(payload([review(body=part)], files=["a.py"])))
         out = self.out.getvalue()
         self.assertIn("coverage=PARTIAL ", out)
-        self.assertIn("status=COVERAGE_IS_PARTIAL", out)
+        self.assertIn("status=COVERAGE_IS_PARTIAL the review covering the head states it", out)
+        self.assertNotIn("may have no review", out)
 
     def test_an_earlier_partial_carries_to_a_head_stating_none(self) -> None:
         part = f"{OVERVIEW}\n<!-- fleet-review: reviewed=1 changed=3 findings=0 -->"
         rounds = [review(oid=OLD, body=part, rid="A"), review(body=OVERVIEW, rid="B")]
         self.assertEqual(42, self.status(payload(rounds, files=["a.py"])))
+        line = next(ln for ln in self.out.getvalue().splitlines() if ln.startswith("status="))
+        self.assertIn("because an earlier round states partial coverage", line)
+        self.assertNotIn("the review covering the head states", line)
+        self.assertIn("A round on the head stating full coverage clears this", line)
+        self.assertNotIn("A re-request is not the remedy", line)
+
+    def test_an_earlier_partial_carried_past_an_unbelievable_head_says_so(self) -> None:
+        part = f"{OVERVIEW}\n<!-- fleet-review: reviewed=1 changed=3 findings=0 -->"
+        odd = f"{OVERVIEW}\n<!-- fleet-review: reviewed=4 changed=3 findings=0 -->"
+        rounds = [review(oid=OLD, body=part, rid="A"), review(body=odd, rid="B")]
+        self.assertEqual(42, self.status(payload(rounds, files=["a.py"])))
+        line = next(ln for ln in self.out.getvalue().splitlines() if ln.startswith("status="))
+        self.assertIn("a round on the head states a reading this cannot believe", line)
+        self.assertNotIn("the review covering the head states", line)
 
     def test_a_prose_partial_on_an_earlier_round_keeps_a_table_from_standing_in(self) -> None:
         part = f"{OVERVIEW}\nCopilot reviewed 1 out of 2 changed files.\n"