Declare every partial supersession in both records and check it, so a reader who follows a citation to the older record learns what no longer holds

00-META/checks/README.md

@@ -26,6 +26,7 @@ indistinguishable from one that cannot.
 | `rests-on` | `decisions:` and `extends:` name records that exist and are **accepted** | the class behind both incidents |
 | `live-citation` | a governing document citing a **superseded** record names its replacement in the same paragraph | `01-to-be/README.md` citing ADR 0022 as live guidance |
 | `supersession` | if A says it was superseded by B, B says it supersedes A | ADR 0012 never declared that it superseded 0011 |
+| `partial-supersession` | a record's `supersedes-in-part:` names records that exist, each carrying a dated *Superseded in part* note naming it under its heading; and every such note is named back by its superseder's field | 11 of 21 partial supersessions had no note on the record they change, and 6 more were said only in prose ([research 045](../../01-RESEARCH/045-a-knowledge-base-the-mesh-writes/00-overview.md)) |
 | `numbering` | the number in the filename is the number in the heading | — |
 | `topics` | every record names a topic of the reading order in `02-DECISIONS/README.md` | — |
 | *(index.py)* | the reading order is written, every record's topic is one of it, and the README stores no list of records ([ADR 0248](../../02-DECISIONS/0248-the-decision-index-is-generated-when-it-is-read-and-never-stored.md)) | a stored list made every two open decisions conflict ([issue 297](../../04-ISSUES/297-two-open-decisions-always-conflict/00-report.md)); it failed on the README of `main` before the list was removed |

00-META/checks/records.py

@@ -264,6 +264,53 @@ def check_supersession_symmetry(failures, records):
             )
 
 
+PARTIAL_MARK = re.compile(
+    r"^> \*\*Superseded in part — (\d{4}-\d{2}-\d{2}), by \[ADR (\d{4})\]\(", re.M
+)
+
+
+def check_partial_supersession(failures, records):
+    """A record superseded in part says so under its heading, and its superseder names it.
+
+    A partial supersession was written only in the newer record's prose six times, and 11 of the
+    21 `supersedes-in-part:` links had no note on the record they change, so a reader who arrived
+    at the older record by a citation read a rule that no longer held. Both directions are
+    checked: the field on the newer record and the dated note on the older one, naming each other.
+    """
+    for number, record in records.items():
+        claimed = record["front"].get("supersedes-in-part", [])
+        if isinstance(claimed, str):
+            claimed = [claimed] if claimed else []
+        for entry in claimed:
+            match = ADR_FILE.match(os.path.basename(entry))
+            if not match or match.group(1) not in records:
+                failures.add("partial-supersession", rel(record["path"]), f"no such record: {entry}")
+                continue
+            older = records[match.group(1)]
+            marks = [by for _, by in PARTIAL_MARK.findall(older["text"])]
+            if number not in marks:
+                failures.add(
+                    "partial-supersession",
+                    rel(older["path"]),
+                    f"ADR {number} supersedes this in part; this record carries no "
+                    f"'> **Superseded in part — YYYY-MM-DD, by [ADR {number}](…).**' note",
+                )
+        for _, by in PARTIAL_MARK.findall(record["text"]):
+            if by not in records:
+                failures.add("partial-supersession", rel(record["path"]), f"note names no such record: ADR {by}")
+                continue
+            names = records[by]["front"].get("supersedes-in-part", [])
+            if isinstance(names, str):
+                names = [names] if names else []
+            if record["name"] not in [os.path.basename(str(n)) for n in names]:
+                failures.add(
+                    "partial-supersession",
+                    rel(records[by]["path"]),
+                    f"ADR {number} says this supersedes it in part; this record's "
+                    f"`supersedes-in-part:` does not name it",
+                )
+
+
 def check_topics(failures, records):
     """Every record names a topic of the reading order.
 
@@ -406,6 +453,7 @@ def main():
     check_rests_on(failures, records)
     check_live_citations(failures, records)
     check_supersession_symmetry(failures, records)
+    check_partial_supersession(failures, records)
     check_numbering(failures, records)
     check_topics(failures, records)
     check_status_against_code(failures)