MaxGhenis · Sep 27, 2026 · Sep 7, 2026 · Sep 7, 2026 · Sep 26, 2026 · Sep 27, 2026
diff --git a/changelog.d/884-parent-ids-export.added.md b/changelog.d/884-parent-ids-export.added.md
@@ -0,0 +1 @@
+US person input columns `parent_1_id` and `parent_2_id`: the CPS ASEC `PEPAR1`/`PEPAR2` pointers resolved to a co-resident parent's `person_id` (0 when unknown or absent), so downstream rules can ask whose child a person is rather than only how many children an adult has.
diff --git a/docs/evidence/spec-engine/us-f0-coverage.json b/docs/evidence/spec-engine/us-f0-coverage.json
@@ -4,9 +4,9 @@
     "version": 1
   },
   "country": "us",
-  "documentation_sha256": "911b21d13cc214601cfb537c538fed2851e5166e8f72de5ebfce5f2918af43d3",
+  "documentation_sha256": "0931cbd3aae2abcd8c072b78eba40c1c006b1bf7fa23c6a6681f9a895e47070e",
   "field_usage": {
-    "authored_normative_field_count": 32400,
+    "authored_normative_field_count": 32404,
     "claim_count": 49,
     "claims": [
       {
@@ -514,8 +514,8 @@
         ],
         "mode": "legacy_behavior",
         "pointer_class": "all",
-        "pointer_count": 1712,
-        "pointer_sha256": "a46d5e657d919db23ee7752d844bd8bbe59c15321dec07102837452d7994d8dd",
+        "pointer_count": 1716,
+        "pointer_sha256": "3e808ed9f5a791c0dfb85be0c59adf803366bf6e8c7a9f5a58f92974e044b607",
         "rationale": null,
         "relative_sink_prefix": "/source_manifest/stages",
         "source_prefix": "/authored/spec~1sources.yaml/stages",
@@ -772,20 +772,20 @@
         "verifier": "vintages"
       }
     ],
-    "configuration_field_count": 42180,
-    "consumed_field_count": 42180,
+    "configuration_field_count": 42184,
+    "consumed_field_count": 42184,
     "generation0_effect_counts": {
-      "legacy_behavior": 38494,
+      "legacy_behavior": 38498,
       "no_generation0_effect": 3686
     },
     "mode_counts": {
       "compiler_semantic": 27717,
       "front_end_validation": 354,
       "identity_only": 103,
-      "legacy_behavior": 14006
+      "legacy_behavior": 14010
     },
     "multiple_primary_use_field_count": 0,
-    "pointer_inventory_sha256": "21b6fe2f6b96307f8ec7d20d4162ee2e0702f363bb28ebd3fa47a4cf7fc12ed4",
+    "pointer_inventory_sha256": "8f655670b9794adae905ede64bdceba6395eeb8d642b6c5896d5c516f1f6a6a7",
     "resolved_binding_field_count": 9780,
     "unused_field_count": 0
   },
@@ -1361,12 +1361,12 @@
         ],
         "expected": {
           "producer_count": 38,
-          "sha256": "6abbfad73014ce3bac9fbd549f16e4a5e645a3b0fbd450b56e186876f3f0dd95"
+          "sha256": "cc34ba11288d01145fc2dc1a669df3f7c4ef2019d73afb02dd8eeee852b16d20"
         },
         "failures": [],
         "observed": {
           "producer_count": 38,
-          "sha256": "6abbfad73014ce3bac9fbd549f16e4a5e645a3b0fbd450b56e186876f3f0dd95"
+          "sha256": "cc34ba11288d01145fc2dc1a669df3f7c4ef2019d73afb02dd8eeee852b16d20"
         },
         "status": "covered"
       },
@@ -1656,13 +1656,13 @@
           "compiler_ir.node_slices"
         ],
         "expected": {
-          "map_sha256": "dad44808366198b8826823b837c7b592c9ecee2299adbd9f8a20251dd6d0b00a",
-          "protocol_sha256": "5f6d3b527060bc6f15f1871c64a42994d4882ee5962f3350ea8a71a83ffcd6bf"
+          "map_sha256": "3cf10a524310ea0ada18ddc65cfa585d1d0652d23e7d7a180c050ac686224e28",
+          "protocol_sha256": "91989ed5e366e19598f86335b2e66723dcb2b6481a78d0dbeb83183a1aa09bd4"
         },
         "failures": [],
         "observed": {
-          "map_sha256": "dad44808366198b8826823b837c7b592c9ecee2299adbd9f8a20251dd6d0b00a",
-          "protocol_sha256": "5f6d3b527060bc6f15f1871c64a42994d4882ee5962f3350ea8a71a83ffcd6bf"
+          "map_sha256": "3cf10a524310ea0ada18ddc65cfa585d1d0652d23e7d7a180c050ac686224e28",
+          "protocol_sha256": "91989ed5e366e19598f86335b2e66723dcb2b6481a78d0dbeb83183a1aa09bd4"
         },
         "status": "covered"
       },
@@ -1677,7 +1677,7 @@
           "compiler_ir.seed_stream_map"
         ],
         "expected": {
-          "implementation_sha256": "5f6d3b527060bc6f15f1871c64a42994d4882ee5962f3350ea8a71a83ffcd6bf",
+          "implementation_sha256": "91989ed5e366e19598f86335b2e66723dcb2b6481a78d0dbeb83183a1aa09bd4",
           "protocol": "legacy-v1",
           "streams": [
             "build_model",
@@ -1698,7 +1698,7 @@
         },
         "failures": [],
         "observed": {
-          "implementation_sha256": "5f6d3b527060bc6f15f1871c64a42994d4882ee5962f3350ea8a71a83ffcd6bf",
+          "implementation_sha256": "91989ed5e366e19598f86335b2e66723dcb2b6481a78d0dbeb83183a1aa09bd4",
           "protocol": "legacy-v1",
           "streams": [
             "build_model",
@@ -1775,12 +1775,12 @@
           "legacy_adapter.imputation.late_producer_resource_semantics"
         ],
         "expected": {
-          "sha256": "a87278445d928ea20e15935a8cc07312d6e819e34409b04e8c814f17910d828f",
+          "sha256": "f4f8bfeb79268a4043a843b47cec1d1c0e58e9f5dd6bc23417ada95446dd7b8e",
           "stages": 37
         },
         "failures": [],
         "observed": {
-          "sha256": "a87278445d928ea20e15935a8cc07312d6e819e34409b04e8c814f17910d828f",
+          "sha256": "f4f8bfeb79268a4043a843b47cec1d1c0e58e9f5dd6bc23417ada95446dd7b8e",
           "stages": 38
         },
         "status": "covered"
@@ -1887,7 +1887,7 @@
             "alpha",
             "zeta"
           ],
-          "sha256": "b1d5c65254b51897b27f0f5e44e344781ce9e01e305aaf1bfc042cc32bc417dc"
+          "sha256": "b7a336af7cb300905d09ad9a33aa1a624f878c2471352d4e252fa69db55aee17"
         },
         "failures": [],
         "observed": {
@@ -1911,7 +1911,7 @@
             "alpha",
             "zeta"
           ],
-          "sha256": "b1d5c65254b51897b27f0f5e44e344781ce9e01e305aaf1bfc042cc32bc417dc"
+          "sha256": "b7a336af7cb300905d09ad9a33aa1a624f878c2471352d4e252fa69db55aee17"
         },
         "status": "covered"
       },
@@ -1975,7 +1975,7 @@
             "take_up_contract",
             "us_qbi_reconciliation_contract"
           ],
-          "sha256": "5b65545ed6f351b30e94ab1405e13d2c7f692ae0c8d4959badcfe9bb9d52d455"
+          "sha256": "61a5484eab9fae1d6651b3ae15f1793d4934ea2f6ed2c08d05716b745c221014"
         },
         "status": "covered"
       },
@@ -2599,7 +2599,7 @@
       "country": "us",
       "schema_id": "country_spec",
       "schema_version": 1,
-      "spec_sha256": "f830589331dad583398485de5724dace0714d8526fb63b37f81cd783b1cb8f30"
+      "spec_sha256": "1cf1f44d9a11458f59ea7d75dce68303816cab3e66668a6c6f6ecfe62d56f8dc"
     }
   },
   "report_schema_version": 3,
@@ -2609,7 +2609,7 @@
     "country": "us",
     "schema_id": "country_spec",
     "schema_version": 1,
-    "spec_sha256": "f830589331dad583398485de5724dace0714d8526fb63b37f81cd783b1cb8f30"
+    "spec_sha256": "1cf1f44d9a11458f59ea7d75dce68303816cab3e66668a6c6f6ecfe62d56f8dc"
   },
   "status": "pass"
 }
diff --git a/docs/us-multispine-operator-ordering.md b/docs/us-multispine-operator-ordering.md
@@ -1066,7 +1066,7 @@ runs:
 | Relationships | pre | Household-head status is a rent-recipient predictor. |
 | Medicare take-up | post | Rowwise carry/completion is clone-safe. |
 | Housing inputs | pre | Rent is drawn once per source household and then cloned unchanged. |
-| Eligibility inputs | pre | Raw `PH_SEQ`/`A_LINENO` parent pointers would count every cloned child twice. |
+| Eligibility inputs | pre | Raw `PH_SEQ`/`A_LINENO` parent pointers would count every cloned child twice, and `PH_SEQ` collides between the ASEC and ACS spines, so the stage runs on the CPS-evidence projection. Its `parent_1_id`/`parent_2_id` outputs name a `person_id`, so the support clone shifts them with the rest of the person id surface ([microcosm#884](https://github.com/PolicyEngine/microcosm/issues/884)). |
 | Pregnancy | post | Stable source-identity hashes share draws across clones. |
 | WIC | post | Remapped family grouping and source-identity draws are clone-safe. |
 | Housing assistance | post | The QRF intentionally replaces only the PUF support role. |

diff --git a/packages/microcosm-build/src/microcosm/build/input_mass.py b/packages/microcosm-build/src/microcosm/build/input_mass.py
@@ -22,7 +22,15 @@
 
 from microcosm.frame import Frame
 
-__all__ = ["input_mass_totals"]
+__all__ = ["PERSON_REFERENCE_COLUMNS", "input_mass_totals"]
+
+#: Person columns whose values name another person (a co-resident parent's
+#: ``person_id``, ``0`` = unknown; microcosm#884). Like entity ids they are
+#: labels, not measured quantities: their weighted sum means nothing and moves
+#: whenever person ids are renumbered, so a parity comparison against a release
+#: on a different id space would fail for no reason. They are skipped as
+#: structural in every schema that carries them.
+PERSON_REFERENCE_COLUMNS: frozenset[str] = frozenset({"parent_1_id", "parent_2_id"})
 
 
 def input_mass_totals(
@@ -35,8 +43,8 @@ def input_mass_totals(
     Every non-structural numeric column is summed under the owning entity's
     effective weights (household weights broadcast through membership for
     entities without their own vector); boolean columns total their weighted
-    ``True`` mass. String/enum columns and structural columns (entity ids and
-    person membership ids) are skipped.
+    ``True`` mass. String/enum columns and structural columns (entity ids,
+    person membership ids, and :data:`PERSON_REFERENCE_COLUMNS`) are skipped.
 
     Args:
         frame: A microcosm frame in any country schema.
@@ -56,7 +64,7 @@ def input_mass_totals(
     """
 
     schema = frame.schema
-    structural = {schema.person_id_column}
+    structural = {schema.person_id_column, *PERSON_REFERENCE_COLUMNS}
     for group in schema.group_entities:
         structural.add(schema.id_column(group))
         structural.add(schema.membership_column(group))

diff --git a/packages/microcosm-build/src/microcosm/build/spec_engine/field_usage.py b/packages/microcosm-build/src/microcosm/build/spec_engine/field_usage.py
@@ -26,9 +26,9 @@
 )
 from .schemas import load_schema_registry
 
-EXPECTED_AUTHORED_FIELD_COUNT = 32_400
+EXPECTED_AUTHORED_FIELD_COUNT = 32_404
 EXPECTED_RESOLVED_BINDING_FIELD_COUNT = 9_780
-EXPECTED_CONFIGURATION_FIELD_COUNT = 42_180
+EXPECTED_CONFIGURATION_FIELD_COUNT = 42_184
 
 
 class FieldUsageError(AssertionError):
@@ -485,8 +485,8 @@ def _path_inventory(rows: Sequence[tuple[str, object]]) -> tuple[int, str]:
         "d6782c5de5bbed1bdc6bf653c4a6d4aadcad4ccc72d35e1092e130fcb04680a3",
     ),
     "source_stages": (
-        1_712,
-        "a46d5e657d919db23ee7752d844bd8bbe59c15321dec07102837452d7994d8dd",
+        1_716,
+        "3e808ed9f5a791c0dfb85be0c59adf803366bf6e8c7a9f5a58f92974e044b607",
     ),
     "spine_assembly_household_mass_shares": (
         2,

diff --git a/packages/microcosm-build/src/microcosm/build/spec_engine/inventory_coverage.py b/packages/microcosm-build/src/microcosm/build/spec_engine/inventory_coverage.py
@@ -350,18 +350,18 @@
     "acs_person_predictors": "878c788a6f037d7aca12b3586ea034eff04f3034ffa11935a736493042551f25",
     "authority": "9d4a9672a0f03039b1fe874b9fe21ed575be0d29f14afc396d03cdf5c809bdd2",
     "early_families": "4aa9f736fd76e83955477ad1667e58f48f264783f05bdc7f0102cd32d61323bd",
-    "full_checkpoint": "b1d5c65254b51897b27f0f5e44e344781ce9e01e305aaf1bfc042cc32bc417dc",
+    "full_checkpoint": "b7a336af7cb300905d09ad9a33aa1a624f878c2471352d4e252fa69db55aee17",
     "gap_fill_schedule": "1c31f9868f7884347cc19cf1ff65da43f950b9114941a715bab168246db414a7",
     "graph_nodes": "40cd51ffdfe2e9d9d08d48c08e8ded9de1e4b134783bab05c4abc6ad5c72ca1e",
     "geography_assignment": "f49425ca8734ac559c73cf44f6458d86d3162a48956b98a27e6e758959361585",
     "late_families": "d91f9ff0eb52f43e7b6eed3d5c58c37abe1620c3a11021da15dae9c10e16d382",
-    "late_resource_semantics": "6abbfad73014ce3bac9fbd549f16e4a5e645a3b0fbd450b56e186876f3f0dd95",
+    "late_resource_semantics": "cc34ba11288d01145fc2dc1a669df3f7c4ef2019d73afb02dd8eeee852b16d20",
     "late_schedule": "e59c019d3d454eac99ac0ac209b6c5b6faaf9bdfcaeee18c36a25be19bf7da2f",
     "ownership": "5f64f0aac49e2313177564f71876bffc8c81b3ded4df701e70930e60e9c98356",
     "primary_tuples": "fdf23da429f8c501e198a2f5b719763d523a41565c2153fdf17b0344f21bcd7c",
-    "seed_map": "dad44808366198b8826823b837c7b592c9ecee2299adbd9f8a20251dd6d0b00a",
-    "seed_protocol": "5f6d3b527060bc6f15f1871c64a42994d4882ee5962f3350ea8a71a83ffcd6bf",
-    "source_manifest": "a87278445d928ea20e15935a8cc07312d6e819e34409b04e8c814f17910d828f",
+    "seed_map": "3cf10a524310ea0ada18ddc65cfa585d1d0652d23e7d7a180c050ac686224e28",
+    "seed_protocol": "91989ed5e366e19598f86335b2e66723dcb2b6481a78d0dbeb83183a1aa09bd4",
+    "source_manifest": "f4f8bfeb79268a4043a843b47cec1d1c0e58e9f5dd6bc23417ada95446dd7b8e",
     "take_up": "9522ce40f7dea569312dd7a7beb474e5a5afadd2f1e10cb5876534c3ef623d35",
     "tail": "ac92829c88a1a4fb6460d61190918d5d99c6c377fc8dd8f62f02b332d09bf59c",
 }

diff --git a/packages/microcosm-build/src/microcosm/build/us/source_stages.json b/packages/microcosm-build/src/microcosm/build/us/source_stages.json
@@ -2227,13 +2227,17 @@
         "is_blind",
         "is_full_time_college_student",
         "own_children_in_household",
+        "parent_1_id",
+        "parent_2_id",
         "veterans_benefits"
       ],
       "nonnegative_outputs": [
         "own_children_in_household",
+        "parent_1_id",
+        "parent_2_id",
         "veterans_benefits"
       ],
-      "notes": "Direct mappings of measured ASEC demographic variables reproducing the retired enhanced-CPS pipeline's constructions (each cited to the retired pipeline's source files in the stage module): is_disabled <- any PEDIS* difficulty item == 1, aligned with reported SSI (under-65 SSI_VAL > 0 implies disabled \u2014 the retired align_reported_ssi_disability rule from datasets/cps/takeup.py, applied to is_disabled in cps.py); is_blind <- PEDISEYE == 1; is_full_time_college_student <- A_HSCOL == 2 & A_FTPT == 1 (the retired primary branch; census_cps.py loads A_FTPT, so the published surface ran the strict form \u2014 the A_HSCOL-only fallback for loads without A_FTPT is not reproduced); own_children_in_household <- count of household members whose PEPAR1/PEPAR2 parent pointers resolve to the person within PH_SEQ; veterans_benefits <- VET_VAL. Nothing is imputed. Without this stage every input takes its engine default (False/0), erasing SNAP disability, student, parent/child, and veteran exemption channels (microcosm #244/#248). is_veteran is formula-owned in PolicyEngine-US (derived from veterans_benefits) and is deliberately not exported (microcosm #24)."
+      "notes": "Direct mappings of measured ASEC demographic variables reproducing the retired enhanced-CPS pipeline's constructions (each cited to the retired pipeline's source files in the stage module): is_disabled <- any PEDIS* difficulty item == 1, aligned with reported SSI (under-65 SSI_VAL > 0 implies disabled \u2014 the retired align_reported_ssi_disability rule from datasets/cps/takeup.py, applied to is_disabled in cps.py); is_blind <- PEDISEYE == 1; is_full_time_college_student <- A_HSCOL == 2 & A_FTPT == 1 (the retired primary branch; census_cps.py loads A_FTPT, so the published surface ran the strict form \u2014 the A_HSCOL-only fallback for loads without A_FTPT is not reproduced); own_children_in_household <- count of household members whose PEPAR1/PEPAR2 parent pointers resolve to the person within PH_SEQ; parent_1_id/parent_2_id <- the person_id of the co-resident member the person's PEPAR1/PEPAR2 pointer names within PH_SEQ, 0 when the pointer is absent or resolves to no co-resident line (microcosm#884; the relation behind the count, consumed by policyengine-us#9404); veterans_benefits <- VET_VAL. Nothing is imputed. Without this stage every input takes its engine default (False/0), erasing SNAP disability, student, parent/child, and veteran exemption channels (microcosm #244/#248). is_veteran is formula-owned in PolicyEngine-US (derived from veterans_benefits) and is deliberately not exported (microcosm #24)."
     },
     {
       "stage": "pregnancy",

diff --git a/packages/microcosm-build/src/microcosm/build/us/spec/sources.yaml b/packages/microcosm-build/src/microcosm/build/us/spec/sources.yaml
@@ -99,7 +99,7 @@ sources:
 stage_asset:
   id: source_stages
   path: microcosm.build.us/source_stages.json
-  sha256: 9f4f983091fb18dea8f4524cc100be20f9fca2b006435461592f8edf53c9a5d8
+  sha256: e75217c0db3075bf2664492167d31ce7ee82c2c5f6a70e3b67e8bb6f4ddd7ecf
 stage_manifest:
   version: 1
   country: us
@@ -2222,9 +2222,13 @@ stages:
   - is_blind
   - is_full_time_college_student
   - own_children_in_household
+  - parent_1_id
+  - parent_2_id
   - veterans_benefits
   nonnegative_outputs:
   - own_children_in_household
+  - parent_1_id
+  - parent_2_id
   - veterans_benefits
   notes: 'Direct mappings of measured ASEC demographic variables reproducing the retired enhanced-CPS
     pipeline''s constructions (each cited to the retired pipeline''s source files in the stage module):
@@ -2234,10 +2238,12 @@ stages:
     A_FTPT == 1 (the retired primary branch; census_cps.py loads A_FTPT, so the published surface ran
     the strict form — the A_HSCOL-only fallback for loads without A_FTPT is not reproduced); own_children_in_household
     <- count of household members whose PEPAR1/PEPAR2 parent pointers resolve to the person within PH_SEQ;
-    veterans_benefits <- VET_VAL. Nothing is imputed. Without this stage every input takes its engine
-    default (False/0), erasing SNAP disability, student, parent/child, and veteran exemption channels
-    (microcosm #244/#248). is_veteran is formula-owned in PolicyEngine-US (derived from veterans_benefits)
-    and is deliberately not exported (microcosm #24).'
+    parent_1_id/parent_2_id <- the person_id of the co-resident member the person''s PEPAR1/PEPAR2 pointer
+    names within PH_SEQ, 0 when the pointer is absent or resolves to no co-resident line (microcosm#884;
+    the relation behind the count, consumed by policyengine-us#9404); veterans_benefits <- VET_VAL. Nothing
+    is imputed. Without this stage every input takes its engine default (False/0), erasing SNAP disability,
+    student, parent/child, and veteran exemption channels (microcosm #244/#248). is_veteran is formula-owned
+    in PolicyEngine-US (derived from veterans_benefits) and is deliberately not exported (microcosm #24).'
 - stage: pregnancy
   survey: Census CPS ASEC + CDC natality-derived national pregnancy rate
   source: https://www.cdc.gov/nchs/nvss/births.htm

diff --git a/packages/microcosm-build/src/microcosm/build/us_runtime/__init__.py b/packages/microcosm-build/src/microcosm/build/us_runtime/__init__.py
@@ -243,6 +243,7 @@
 from microcosm.build.us_runtime.eligibility_inputs import (
     US_ELIGIBILITY_INPUTS_NONCONSTANT_PERSON_COLUMNS,
     US_ELIGIBILITY_INPUTS_OUTPUT_COLUMNS,
+    US_ELIGIBILITY_INPUTS_PARENT_ID_COLUMNS,
     US_ELIGIBILITY_INPUTS_REQUIRED_SOURCE_COLUMNS,
     US_ELIGIBILITY_INPUTS_STAGE_NAME,
     derive_us_eligibility_inputs_from_manifest,
@@ -1249,6 +1250,7 @@
     "us_pregnancy_summary",
     "with_us_pregnancy_inputs",
     "US_ELIGIBILITY_INPUTS_NONCONSTANT_PERSON_COLUMNS",
+    "US_ELIGIBILITY_INPUTS_PARENT_ID_COLUMNS",
     "US_ELIGIBILITY_INPUTS_OUTPUT_COLUMNS",
     "US_ELIGIBILITY_INPUTS_REQUIRED_SOURCE_COLUMNS",
     "US_ELIGIBILITY_INPUTS_STAGE_NAME",
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		US person input columns `parent_1_id` and `parent_2_id`: the CPS ASEC `PEPAR1`/`PEPAR2` pointers resolved to a co-resident parent's `person_id` (0 when unknown or absent), so downstream rules can ask whose child a person is rather than only how many children an adult has.