Read scorecard#183's base-side grid record and apply known gaps

changelog.d/636.added.md

@@ -0,0 +1 @@
+Qualification reads policyengine-scorecard#183's receipts. The vendored replay receipt schema and its mirrors now carry the base's own grid record (`diff.base_events`) and the candidate's missing and unsupported measure-years. A gap counts as known only when the base's record lists the same measure-year as inert, or missing and supported.

src/policyengine/data/qualification/replay_policy.md

@@ -2,38 +2,69 @@
 
 Decided under cos d1344 by workstream W4 on 15 October 2026, after two
 independent reviews. The pull request that added this file records the
-decision, the reviews and the alternatives considered.
+decision, the reviews and the alternatives considered. Revised on 16
+October 2026, before first use, after the third to fifth reviews of
+policyengine.py#637: scorecard's own record of a mixed known gap no longer
+blocks, flag counters must equal the flags the rows carry, and any
+candidate value other than £0 at a known gap is a contradiction.
 `evaluate_replay_receipt` in `policyengine.provenance.qualification`
 applies this text. Each qualification receipt records the policy id and
 this file's SHA-256 in its `replay` gate details.
 
 The replay gate fails on the regressions a scorecard replay receipt
 identifies. It calls a gap known only on positive evidence from the
-comparison base. It sends every other flagged move to a named reviewer.
+comparison base, and passes the rows that record a known gap. It sends
+every other flagged move to a named reviewer.
 
 ## Fail
 
 - A rejected request, `no_supported_years`, integrity `failed` (a crash or
   missing outputs, persistent or not), or a receipt not bound to the
   request.
-- A mapping flag, whether a flagged row carries it or only the receipt's
-  counters state it.
-- A lost result: a coverage row with a base value and no candidate value.
-- A lost response, unless it is a known gap:
-  - a measure-year the candidate lists as inert;
+- A mapping flag.
+- A lost result: a coverage row with a base value and no candidate value,
+  unless it is the record of a known gap (below).
+- A lost response:
+  - a measure-year the candidate lists as inert, unless it is a known gap;
   - a measure-year total at exactly £0 where the base's absolute value is
     at least the diff's bound, max(£1m, 1% of the base's absolute value),
-    whether the base was positive or negative.
+    whether the base was positive or negative. A known gap never excuses
+    this: a base whose record lists the measure-year as a gap cannot also
+    hold a material value for it.
 - An event whose supported grid is incomplete, unless every inert or
-  missing measure-year in it is a known gap. A receipt whose integrity is
-  `incomplete` with no incomplete event also fails.
+  missing and supported measure-year in it is a known gap. An incomplete
+  event whose receipt does not list its missing measure-years fails, and so
+  does one with no inert and no missing and supported measure-year at all.
+  A receipt whose integrity is `incomplete` with no incomplete event also
+  fails.
+- A receipt that contradicts itself, including a complete event that lists
+  an inert, or missing and supported, measure-year; flag counters that
+  differ, either way, from the flags its rows carry; and a candidate value
+  other than £0 for a measure-year that is a known gap.
 
 ## Known gaps
 
-A measure-year is a known gap only when the receipt positively records it
-as inert, or missing and supported, in the base, for the same event,
-measure and year. Until the receipt carries that base-side record, there
-are no known gaps.
+A candidate measure-year that is inert, or missing and supported (in the
+event's missing list and not its unsupported list), is a known gap only
+when the receipt's base-side record for the same event (`diff.base_events`,
+taken from the base's verified staging and run manifests) lists the same
+measure and year as inert, or as missing and supported, in the base. The
+gate records each known gap with the base's staging manifest SHA-256. A
+legacy-layout base, or an event the base did not replay, has no record, so
+none of its gaps are known.
+
+A known gap does not block. Where one side is inert and the other missing,
+scorecard records the gap as a coverage row with exactly £0 on the inert
+side and no value on the other, and an inertness flag on the inert side
+only, on a row with no values. Those flags are the gap itself and neither
+fail nor send the row to review. (Where the candidate is the inert side, its
+inert list already decides that flag.) The gate records every row a known
+gap accounts for, in whole or in part, beside the known gaps; the rest of a
+partly excused row's flags are judged as usual. Any other row at a known gap
+is judged as usual: a coverage row with a base value and no candidate value,
+even £0, is still a lost result, and any candidate value other than £0 at a
+known gap contradicts the candidate's own record, which lists the
+measure-year as inert (exactly £0) or missing (no value).
 
 ## Review
 
@@ -48,8 +79,9 @@ review:
 - support flags (the separate `supported_years` gate fails a candidate that
   loses a year the previous certificate supported);
 - coverage gains, coverage rows with no value on either side, and any other
-  coverage row that is not a lost result;
-- inertness flags on a measure-year the candidate does not list as inert;
+  coverage row that is not a lost result or the record of a known gap;
+- inertness flags on a measure-year the candidate does not list as inert,
+  other than the record of a known gap;
 - a receipt with no diff against a certified variant.
 
 Unsupported years alone never fail. A move below the diff's bound raises

src/policyengine/data/schemas/vendor/policyengine-scorecard/README.md

@@ -1,7 +1,9 @@
 # Vendored policyengine-scorecard schemas
 
-Copied unchanged from PolicyEngine/policyengine-scorecard, branch
-`w6/replay-variants`, commit `dc040de` (`docs/uk_replay/schemas/`): the v1
+Copied unchanged from PolicyEngine/policyengine-scorecard, `main` at commit
+`71cad306f37f7f9bfb4b58497ff9ddd78b396e00` (the merge of scorecard#183, which
+added `diff.base_events` and the corpus grid lists;
+`docs/uk_replay/schemas/`): the v1
 pre-promotion replay interface between policyengine.py qualification (W4)
 and the replay corpus (W6). `policyengine.provenance.qualification` mirrors
 them, and `tests/test_qualification_contracts.py` checks the mirrors and the

src/policyengine/data/schemas/vendor/policyengine-scorecard/replay_receipt.v1.json

@@ -364,6 +364,12 @@
          }
         }
        }
+      },
+      "base_events": {
+       "type": "object",
+       "additionalProperties": {
+        "$ref": "#/$defs/base_event"
+       }
       }
      }
     }
@@ -614,23 +620,74 @@
      "type": "boolean"
     },
     "inert_measure_years": {
+     "$ref": "#/$defs/measure_years"
+    },
+    "missing_measure_years": {
+     "$ref": "#/$defs/measure_years"
+    },
+    "unsupported_measure_years": {
+     "$ref": "#/$defs/measure_years"
+    }
+   }
+  },
+  "measure_years": {
+   "type": "array",
+   "items": {
+    "type": "object",
+    "additionalProperties": false,
+    "required": [
+     "measure_key",
+     "year"
+    ],
+    "properties": {
+     "measure_key": {
+      "type": "string",
+      "minLength": 1
+     },
+     "year": {
+      "type": "integer"
+     }
+    }
+   },
+   "uniqueItems": true
+  },
+  "base_event": {
+   "type": "object",
+   "additionalProperties": false,
+   "required": [
+    "staging_manifest_sha256",
+    "run_manifest_sha256",
+    "supported_years",
+    "full_supported_grid_complete",
+    "inert_measure_years",
+    "missing_measure_years",
+    "unsupported_measure_years"
+   ],
+   "properties": {
+    "staging_manifest_sha256": {
+     "$ref": "#/$defs/sha256"
+    },
+    "run_manifest_sha256": {
+     "$ref": "#/$defs/sha256"
+    },
+    "supported_years": {
      "type": "array",
      "items": {
-      "type": "object",
-      "additionalProperties": false,
-      "required": [
-       "measure_key",
-       "year"
-      ],
-      "properties": {
-       "measure_key": {
-        "type": "string"
-       },
-       "year": {
-        "type": "integer"
-       }
-      }
-     }
+      "type": "integer"
+     },
+     "uniqueItems": true
+    },
+    "full_supported_grid_complete": {
+     "type": "boolean"
+    },
+    "inert_measure_years": {
+     "$ref": "#/$defs/measure_years"
+    },
+    "missing_measure_years": {
+     "$ref": "#/$defs/measure_years"
+    },
+    "unsupported_measure_years": {
+     "$ref": "#/$defs/measure_years"
     }
    }
   }