WS-E spine deferrals: known bugs and signed inconsistencies awaiting their increment

[juaristi22]

Parent: #145 (workstream E of the UK-migration epic #665). The spine-lane counterpart of #736 (WS-C calibration deferrals): a central checklist of every deferral, known bug, and signed inconsistency filed while the spine lane landed (#686 → #757 → PR #793), so nothing lives only in a PR body or an adjudication comment. Items graduate to their own issues when they become actionable; the committed signed-differences register (uk/spine_swap_signed_differences.json) remains the authoritative record of every intentional candidate-vs-incumbent deviation.

The capstone: the first certified cut

• Re-certify the candidate-of-record on a post-UK WAS stage: split private pension wealth out of corporate_wealth (#750) #755 spine. UK WAS stage: split private pension wealth out of corporate_wealth (uk-data#452 M2) #750 landed via UK WAS stage: split private pension wealth out of corporate_wealth (#750) #755 (2026-08-28), so spine-i no longer carries the UC lever the dispositions assume; spine-j (data/ukds/acceptance/spine-j-remeasure/, developer full build from main, gates green, private_pension_wealth present) needs the RC-strict battery + ladder + parity instruments + signed-differences re-mint before it can replace spine-i as candidate-of-record. Precedes the cut.
• Cut the first certified microcosm_uk_2024 line. The queue is down to 6 cells, all UC-side (v12, spine-j + the Revise the hmrc SPI band exclusions per the #807 support re-measurement #810 register revision: the 4 Band edges derive from the exclusion-pruned register, silently widening surviving banded targets #792 artifacts cleared with Fix #792: derive band edges from the compiled register, never the pruned roster #803, the sparse-band siblings cleared with the Re-measure the hmrc SPI band exclusions: three 'sparse cell' premises fail on spine-i (hundreds of in-band carriers) #807 lift, CGT slid inside the band): 2 TCL disability cells (UK spine: child disability under-identification blocks the TCL disability cells (−56.5% / −40.0% across three spine vintages) #808) + 3 composition cells and 1 payment band (UC residual after the pension-wealth split: support 4.24m vs 6.76m — re-draw undershoot, the 0.55 take-up freeze, and composition shape #809) — diagnosed as measurement-grain defects (see the 2026-08-28 capstone comments), re-bind PR designed. Also owed before the cut: the RC-strict battery + parity instruments + signed-differences re-mint on a post-UK WAS stage: split private pension wealth out of corporate_wealth (#750) #755 spine (spine-j is a developer build; spine-i's 14/14 battery does not transfer). Blocked-run receipts: data/ukds/acceptance/757-swap/ (13-cell era), runs/uk-623-first-calibrated/spine-assessment-v12/ (current). (2026-08-28 state: the queue is 8 cells on spine-j — the 4 Band edges derive from the exclusion-pruned register, silently widening surviving banded targets #792 artifacts cleared with Fix #792: derive band edges from the compiled register, never the pruned roster #803, and UK WAS stage: split private pension wealth out of corporate_wealth (uk-data#452 M2) #750, now landed and measured (+1.11m UC support, receipts runs/uk-623-first-calibrated/spine-assessment-v11/), moved UC caseload inside/near the bound; the 8 are dispositioned across Re-measure the hmrc SPI band exclusions: three 'sparse cell' premises fail on spine-i (hundreds of in-band carriers) #807 (sibling distortion), UK spine: child disability under-identification blocks the TCL disability cells (−56.5% / −40.0% across three spine vintages) #808 (2 TCL disability cells), UC residual after the pension-wealth split: support 4.24m vs 6.76m — re-draw undershoot, the 0.55 take-up freeze, and composition shape #809 (3–4 UC composition cells + the newly failing COUPLE_WITH_CHILDREN payment band), and obr.capital_gains_tax at exactly −25.0%, an adjudication candidate.)
• B4 completion / C4 (Swap the microcosm-built UK spine into the national build and retire the incumbent feed #757 items 9, 14): flip uk_input_mass_parity's reference to the just-cut line with run provenance, then retire the efrs-post-calibration descriptor and the incumbent filename pin (weighted_integrity.py, microcosm-data/contract.py). Cannot precede the cut (US Export input-mass-parity gate references the raw base, flagging correct calibration gains on PUF-imputed columns #327 doctrine). The frozen eFRS parity extraction stays as the historical instrument.
• W8 (Swap the microcosm-built UK spine into the national build and retire the incumbent feed #757 item 12): certified-identity registry entry for the cut artifact.
• UK scorecard: populace_uk_2023 vs enhanced_frs_2024_25 vs admin benchmarks (2026) #731 scorecard probe + rule-1 scorer seal: run against the certified line; the certification producer already cross-pins the score receipt.
• UK_REFERENCE_DATASET_NAME re-semantics once a second certified line exists — "reference" becomes the previous certified microcosm line (Swap the microcosm-built UK spine into the national build and retire the incumbent feed #757 item 13 note, terminal_gates.py).

Filed spine issues

• Derive NHS allocation (and audit age-conditioned imputations) from the disaggregated age surface #785 — derive NHS allocation (and audit age-conditioned imputations) from the disaggregated age surface; was blocked on the swap certifying, now unblocked by Swap the microcosm spine into the UK national build: self-policing build, retired June path, hardened parity instruments (#757) #787's merge
• UK spine: relationship-to-head frame column, so the ONS household-composition split is measurable #791 — relationship-to-head frame column so the ONS household-composition split is measurable; its three windowed exclusions expire 2026-11-26
• UK WAS stage: split private pension wealth out of corporate_wealth (uk-data#452 M2) #750 — split private_pension_wealth out of corporate_wealth (uk-data#452 M2): landed via UK WAS stage: split private pension wealth out of corporate_wealth (#750) #755 + policyengine-uk#1824 (2.92.0) + floors Floor the uk extra at policyengine-uk>=2.92 for the pension-wealth split (#750) #811; lever measured (UC support +1.11m, caseload −25.6% → −20.8%); residual owned by UC residual after the pension-wealth split: support 4.24m vs 6.76m — re-draw undershoot, the 0.55 take-up freeze, and composition shape #809/UK spine: child disability under-identification blocks the TCL disability cells (−56.5% / −40.0% across three spine vintages) #808 — landed via UK WAS stage: split private pension wealth out of corporate_wealth (#750) #755 and first measured 2026-08-28: UC initial support 3,128,938 → 4,242,978 with non-UC targets untouched; the residual is UC residual after the pension-wealth split: support 4.24m vs 6.76m — re-draw undershoot, the 0.55 take-up freeze, and composition shape #809
• UK CGT top-tail age and geography joints inherit from incidence and look off — benchmark against HMRC marginals #725 — CGT top-tail age and geography joints vs HMRC marginals
• Carry manifest rewrites into the shared Stage/StageRecord producer graph #721 — carry manifest rewrites into the shared Stage/StageRecord producer graph (in-place rewrites make stage-input state unreconstructible; E5's out-of-build refit instrument binds only pre-rebase)
• Tighten the UK input-mass tolerance by receipting the explained top drifts #713 — tighten the UK input-mass tolerance by receipting the explained top drifts (the gate note declares the re-mint procedure)
• Adjudicate the UK spine grain at the ingest/calibration seam #688 — the open half of the spine-grain adjudication (E10 gate arithmetic)
• Net-new UK stages: UC deduction attributes, bus fares, WAS debt #685 — net-new UK stages: UC deduction attributes, bus fares, WAS debt
• Legacy 2023-vintage build of the microcosm UK spine (deferred) #687 — legacy 2023-vintage spine build (deferred)
• policyengine-uk-data#469 — the incumbent's ETB per-head division (upstream defect of the UK: banded CGT gains targets (by size of gain) to constrain the distribution, not just count + total #467 family, observed during E10)
• Re-measure the hmrc SPI band exclusions: three 'sparse cell' premises fail on spine-i (hundreds of in-band carriers) #807 — re-measure the hmrc SPI band exclusions: three "sparse cell" premises fail on spine-i and spine-j (77–1,158 in-band carriers); lifting them re-couples the amount/count pairs (the +38.6% self_employment_income_count_50k_70k sibling distortion is the live symptom)
• UK spine: child disability under-identification blocks the TCL disability cells (−56.5% / −40.0% across three spine vintages) #808 — child disability under-identification on the FRS disability stage: the two TCL disability cells run −56.5% / −40.0%, invariant across spine-c/i/j; blocks 2 of the 8 capstone cells
• UC residual after the pension-wealth split: support 4.24m vs 6.76m — re-draw undershoot, the 0.55 take-up freeze, and composition shape #809 — the UC residual after the pension-wealth split (support 4.24m vs 6.76m): promote the wealth-block re-draw undershoot from UK WAS stage: split private pension wealth out of corporate_wealth (uk-data#452 M2) #750's follow-ups, re-measure the U8 would_claim_uc 0.55 freeze on its requested new evidence, and the composition shape (2-children fails while 1 and 3 fit); owns 3–4 of the 8 capstone cells

Deferrals and signed inconsistencies without their own issue yet

• UK WAS stage: split private pension wealth out of corporate_wealth (uk-data#452 M2) #750 residuals (graduated 2026-08-28 on closure): the composite mass audit (old corporate wealth vs corporate + pension, so the input-mass gate distinguishes the intended transfer from pension-mass loss); the cash-ISA gap (cash_isa is capital for the means tests but the model's savings maps savings accounts only); current_db_pension_wealth (£1,149bn current-employment DB not carried). The mirror→re-pin ordering stays on B4 above; the re-draw undershoot is UC residual after the pension-wealth split: support 4.24m vs 6.76m — re-draw undershoot, the 0.55 take-up freeze, and composition shape #809 M1 + Port UK compact source stages and 2024-25 refresh from uk-data #145.
• macro_realism for the UK (Swap the microcosm-built UK spine into the national build and retire the incumbent feed #757 item 9): named in the arming item but never declared — no uk/gates.json entry and no UK_GATE_REGISTRY binding exist (only the Belgium precedent). Decide arm-or-drop; arming needs a UK metric/band source plus a new binding.
• Household-surface QRF tail gate: the 12 household_qrf_tail grids (was_wealth surface) are measured in the Assemble the microcosm-built UK spine: whole-spine parity and swap acceptance #686 L3 baselines but not armed — uk_qrf_tail_concentration covers the 47-column HMRC person surface only (deferred in PR Complete the #757 deferrals: the exclusion pass, the measured U8 lever, the release-cut certification, and the re-armed thresholds #793; needs a household-surface evidence function and gate entry).
• uk_take_up_signal semantics: the gate sits terminal, so it compares weighted post-calibration shares against unweighted contract targets — not the same statistic pre/post calibration. Flagged during Swap the microcosm spine into the UK national build: self-policing build, retired June path, hardened parity instruments (#757) #787; unruled.
• owned_land seed instability: the winsorised-donor / separate-land-imputation revisit registered on Port UK compact source stages and 2024-25 refresh from uk-data #145 (comment 5341180811); the reviewed input-mass exclusion was re-signed 2026-08-26 on a fresh 25-stage stability receipt (swing persists at 53.8% national) and expires 2026-09-26 — re-sign on fresh evidence or fix before then.
• E8 mass-change reasons: five pre-E8 stage families still declare the generic fallback reason instead of a stage-named one (standing follow-up from the Port the CGT structure, salary sacrifice, and student loan stages onto the UK spine at FRS 2024-25 #740 adversarial round 2).
• E7 reviewed-absent incapacity: hmrc_spi_incapacity_benefit_income is reviewed-absent per the Create the SPI income channel on the microcosm spine with the FRS-only second stage #683 adjudication; the stage fence (not the gate) promotes it when a future FRS vintage carries signal. Standing, self-enforcing — listed so the convention is findable.
• communication_consumption register scope: the one LCFS column where the incumbent is closer on level while the candidate is closer on share; signed inside the donor-faithful class, with a one-line rescope on offer if the adjudicator objects (Assemble the microcosm-built UK spine: whole-spine parity and swap acceptance #686 ledger, still open).
• student_loan_balance direction: signed on the register with the direction unevidenced beyond the E5 donor-truth measurement (Assemble the microcosm-built UK spine: whole-spine parity and swap acceptance #686 ledger, still open).
• UK parity increment 4: port the weighted integrity gates (input-mass parity + QRF tail concentration) into the UK terminal battery (#578) #609 disclosure confirmation for the published parity numbers (carried from the Assemble the microcosm-built UK spine: whole-spine parity and swap acceptance #686 queue).
• Cross-lane markdown sweep (Swap the microcosm-built UK spine into the national build and retire the incumbent feed #757 item 16 remainder): COVERAGE_PROGRESS.md, PROGRESS_BUILD*.md, _698-*.md, _*LANE-NOTES.md, FINAL_REPORT.md — historicize or delete in their own PR; the UK-lane markdowns were dispositioned in Swap the microcosm spine into the UK national build: self-policing build, retired June path, hardened parity instruments (#757) #787.

Standing records (not action items)

• The U8 would_claim_uc lever is measured and re-frozen at 0.55: the raise moves claimants off legacy benefits (housing benefit −0.0% → −52.4%) while leaving every UC cell unchanged; the contract entry carries the receipts. Do not re-raise without new evidence — the lever's disposition is UK WAS stage: split private pension wealth out of corporate_wealth (uk-data#452 M2) #750.
• The spine signed-differences register (14 entries incl. the quantitative bounds re-minted per candidate) is the swap-decision record; per-stage battery gates are the standing health checks.

Refs: #686, #757, PR #793, #736 (calibration counterpart), #665.

[juaristi22]

Capstone-state update from today's remeasure (evidence: runs/uk-623-first-calibrated/spine-assessment-{v10,v11}/):

The blocked-cell queue is now 8, not 13, and its composition changed. The 4 #792 artifacts are gone (#803's band-edge fix), and #750 — landed via #755 and measured for the first time today — moved UC support 3,128,938 → 4,242,978 (+1.11m benefit units) with clean isolation (non-UC initials byte-identical). v11's failing set: 3 UC composition cells (#809), 2 TCL disability cells (#808), 1 newly-failing COUPLE_WITH_CHILDREN payment band (#809), 1 sparse-band sibling distortion (#807 — the excluded amount sibling pushes the surviving count to +38.6%), and obr.capital_gains_tax at exactly −25.0% (forecast-vintage gap; adjudication candidate).

A post-#755 spine exists but is not the candidate-of-record: spine-j (data/ukds/acceptance/spine-j-remeasure/, gates green, private_pension_wealth present) was built today from main as a developer full build — spine-i's 14/14 RC battery, ladder, and signed_parity do not transfer. The cut now needs the RC-strict battery + parity instruments + signed-differences re-mint run on a post-#755 spine; suggest adding that as an explicit checklist item above the capstone, since spine-i no longer carries the UC lever the dispositions assume.

New issues to absorb into the "Filed spine issues" list: #807 (three "sparse cell" exclusion premises fail on both spine-i and spine-j — 77–1,158 in-band carriers; lifting them likely clears the +38.6% sibling), #808 (child disability under-identification, the two deepest cells, invariant across three spine vintages), #809 (the UC residual: re-draw undershoot promotion, the 0.55 take-up freeze's requested new evidence, composition shape).

Minor observation for the calibration counterpart (#736): VAT drifts +10.3% (v9) → +17.5% (v10) → +19.0% (v11) across register/exclusion changes — not blocking, but trending.

[juaristi22]

Capstone-state update — the #807 revision is landed and measured (v12: spine-j, the revised 44-entry register via #810, 364 targets bound; receipts runs/uk-623-first-calibrated/spine-assessment-v12/):

The blocked-cell queue is now 6, all UC-side. The three lifted class-B cells fit (+22.2% / +18.5% / +23.3%), the sparse-band sibling distortion resolved at the source (+38.6% → +0.1%), and obr.capital_gains_tax slid inside the band (−25.01% → −24.9%) — the hmrc SPI band surface is fully green for the first time. Remaining: the two TCL disability cells (#808: −56.5% / −40.2%) and the four #809 cells (composition −36.9% / −28.8% / −26.5%, COUPLE_WITH_CHILDREN payment band −46.4%).

Closures: #807 closed via #810 (revision validated). #750 closes via #811 (engine floor policyengine-uk>=2.92, lock → 2.92.1 — the last microcosm-side checklist item; certification readout on the issue). #792's data claim verified on the issue (the four artifact cells pass at published widths: +128.2% → +0.0% etc.).

#750 residuals graduating to this ledger (from the post-merge checklist): the composite mass audit (old corporate wealth vs corporate + pension, so the input-mass gate distinguishes the intended transfer from pension-mass loss); the cash-ISA gap (capital for the means tests, but the model's savings maps savings accounts only); current_db_pension_wealth (£1,149bn current-employment DB not carried). The uk-data mirror → efrs-post-calibration re-pin ordering stays on the existing B4 bullet; the wealth re-draw undershoot is owned by #809 (mechanism 1) with #145.

Diagnosis of the remaining 6 (exploration receipts on file, plan approved): the two #808 cells and the three #809 composition cells are measurement-grain defects, not spine gaps — the disability children cells sum the affected-children flag against a published all-children concept (sheet 04B counts every child: sibling rows prove exactly 3.00/4.00 children/household), and the composition cells are household-grain measures of DWP's benefit-unit concept (household-summed is_child counts other benunits' children; households_single_no_children is the union of two #791-excluded ONS cells minus their disambiguating predicates — same defect class as #791, but the fix is re-binding to the natively-carried FRS benunit grain, not the relationship-to-head column). The re-bind PR is designed and held pending go-ahead; the COUPLE_WITH_CHILDREN payment band is genuinely benunit-grain and needs the uk-data#452 adjudication or the take-up/composition work (#809 M2).