Conformance record

Oracle is CRA PDOC (https://apps.cra-arc.gc.ca/ebci/rhpd/beta/). PDOC version observed on filled vectors: 2026-06-11 (M1); grid queue: not recorded (the capture read no form controls). Capture operator: pdoc-oracle-harness.

Expected amounts are PDOC-only. They are never filled from the engine.

This file is generated by tools/conformance (takehome-conformance). Do not hand-edit rates or counts; change the run and regenerate.

Overall agreement rate (PDOC corpora): 8905/9002.

With rounding_compat: pdoc (CPP line in binary64, as inferred from PDOC's outputs): 8987/9002.

The engine reproduces PDOC's CPP line exactly under binary64 shortest-decimal rounding (the rounding_compat: pdoc arm). The default arm follows T4127 plus two PDOC-matched roundings T4127's text does not specify: K2/K2P credits and Ontario surtax lines are rounded separately. Both rates count every compared form; nothing is exempted. The July 2026 grid was captured from live PDOC (last capture 2026-09-15). See M-004 and finding 003.

The PDOC corpora use TD1 claim codes 0, 1 and E only, so neither rate says anything about claim codes 2 to 10. Those rest on the CRA claim-code tables and an independent oracle (tools/claim-codes/oracle.py, 384 vectors in crates/takehome-core/tests/vectors/claim_codes_2026.json).

Methodology

A disagreement is: correctly-specified identical inputs, engine and PDOC both given exactly what the operator intended, outputs differ. That is a finding about the world. It is published here with the full input, both outputs, the delta, and an explanation: including cases where PDOC differs from a literal reading of T4127.

A disagreement is not: a bug in the harness, a mis-mapped request or result field, or a vector whose input was specified differently on the two sides. That is a defect. Fix it, add a regression test, and it never appears in this record.

The distinction is the document’s credibility. Inflating the disagreement count with our own mapping bugs is less trustworthy, not more honest. Publishing everything is not the same as publishing indiscriminately. The number of disagreements below means genuine remaining deltas, not “every time a test failed.”

Until every defined vector in a corpus is measured, this document states n, how many are measured, and how many are pending. It does not compute an agreement rate on a partial run. A completed corpus states how many match and lists every disagreement.

M-001: Published whole-dollar K (ADR-002)

Annual T3/T4 is discontinuous by at most $1.00 at each bracket threshold, because the CRA publishes the K constants rounded to whole dollars. PDOC exhibits the same discontinuity; we match it deliberately.

The per-threshold jump equals the difference of that bracket's two K rounding residuals. Measured 2026 jumps for **all thirteen bracket tables** (FED plus twelve provinces/territories; both January and July editions; Outside Canada has no provincial K) live in crates/takehome-core/tests/vectors/bracket_discontinuity_2026.json.

Period-tax vs gross is therefore not strictly monotone. The property ontario_calculate_invariants uses the M-001 bound (≤ $0.09 per period across sampled P ≥ 12). The thirteen-jurisdiction property calculate_invariants_all_jurisdictions scales the same residual difference by P, adds provincial surtax amplification and the Outside Canada 48% T1 surtax, and allows two cents of period rounding. #[ignore] is never a resolution for those tests.

Decision: docs/ADR-002-published-constants.md.

M-002: PDOC K2 maximum in the reaching period

T4127 Chapter 3 tells the calculator to use the maximum base CPP contribution “in that pay period”: the period year-to-date first reaches the annual CPP maximum. PDOC does not. Its federal CPP credit base is max(P × C × ratio, D × ratio) capped at base_max, which on the measured vector is D × ratio = 3494.12 rather than base_max = 3519.45.

The period-tax difference is 13¢ federal and 5¢ provincial on on-biweekly-midyear-k2-max. That is a fact about PDOC, not an engine defect: the default k2_method is pdoc_observed because customers reconcile against the oracle. The document’s reading is selectable as t4127_literal.

Full write-up (vector, both outputs, delta, inversion, reproduction): docs/findings/001-k2-maximum-in-reaching-period.md.

PDOC mapping notes: employee.federal_tax is T4127 [(T1)/P]+L (PDOC Federal + Additional). employee.total_tax is the sum of the two separately rounded federal and provincial lines a user can add up on screen; breakdown.T is T4127 Step 6 round((T1+T2)/P)+L and may differ by one cent. Claim code 1 must be entered via PDOC Claim codes, not a fixed TD1 dollar amount: fixed $16,452 does not phase out BPAF. employee.total_deductions includes union dues.

M-004: PDOC's CPP line matches binary64 (closed 2026-10-22)

Inferred from PDOC's outputs (its code is not public): PDOC's period CPP contribution matches (PI - exemption) x 0.0595 evaluated in IEEE-754 binary64, then rounded half-up from the shortest decimal of that value. On an exact decimal half-cent (150.00 x 0.0595 = 8.925) binary64 holds 8.924999999999999, so PDOC shows 8.92; T4127 decimal gives 8.93. All 82 CPP-line disagreements in the July queue are this case; the rule changes none of the 8,900 CPP lines that already agreed. The default arm keeps decimal arithmetic for C. rounding_compat: pdoc reproduces PDOC with an integer-only binary64 emulator (no floats in the money path). Finding: docs/findings/003-pdoc-cpp-binary64-and-split-credits.md. Decision: docs/ADR-007-pdoc-binary64-cpp.md.

M-003: PDOC midpoint direction (mostly closed 2026-10-22)

Finding 003 closed 149 of the 164 one-cent disagreements with three named rules: K2/K2P as two separately rounded credits, Ontario V1 as two separately rounded surtax lines (both in the default arm) and M-004 above. The original record follows for history.

M-003 (history): PDOC midpoint direction

Live cent delta: T4127 half-up at an exact midpoint goes up; PDOC’s line is sometimes 1¢ lower. Counts against the agreement rate: not exempted as methodology. Not Alberta-specific; AB is dense because 8% flat on round grosses manufactures halves. Observed down-classes: AB provincial T2/P, AB CPP, NL 4333.33 P=12, NL 1718.39 P=26 (neighbour 1718.40 goes up), NU 2536.41 P=22. Cross-jurisdiction probes: 47/50 discriminating half-cent forms match engine (up). Condition that selects down vs up is unnamed. Finished July queue: 164 one-cent disagreements across thirteen jurisdictions (AB 40, ON 18, BC 14, NU 14, NS 12, MB 11, YT 11, NL 10, PE 8, SK 8, NB 6, NT 6, OutsideCanada 6); 780 forms the salary UI accepted as queue items but PDOC step-2 would not advance. Those 780 are named, not pending, and not in the rate.

Product: ADR-003: rounding_compat (t4127 default; pdoc implemented 2026-10-22 per ADR-007 for the CPP line).

Full write-up: docs/findings/002-pdoc-midpoint-direction.md.

M4 named classes (not folded into the Option 1 rate)

• pdoc-bonus-2026: 20 PDOC bonus vectors captured 2026-09-19 through tools/pdoc-oracle (locator: Total current bonus payable). Own class; excluded from the overall Option 1 PDOC rate. One-cent disagreements listed on the corpus; expected amounts stay PDOC.
• year-projection-2026: engine invariants (API tests 22-29). Oracle class invariants. Caps, YMPE/CPP2, BC January/July split, federal sum vs T1 within P cents, 53-week / 27-biweekly exemptions.
• t4127-option2-2026: T4127 Chapter 5 worked examples plus invariants. Live PDOC has no Option 2 control. Weaker evidence than PDOC; does not inherit the Option 1 agreement rate.

PDOC evidence publication (ruling a)

JSON cache records are published as the GitHub release archive takehome-conformance-corpus-2026.1.tar.zst, not in git. pdoc-identity.json and screenshot-hashes.json stay in the repo so the catalog digest is checkable without a 38 MB clone. PNG screenshots stay local (data/pdoc-screenshots/, gitignored). This document records the catalog digest, the archive SHA-256, and the twenty M1 screenshot hashes. Publication tests extract the archive and break the catalog on purpose.

Sampling design

Published PDOC queue: every distinct July live-edition boundary form the salary UI can enter: ten of fourteen legal P, both claim codes, fingerprint-deduped. The earlier 15,264 figure assumed all fourteen P; PDOC cannot capture annual / semi-annual / quarterly / hourly (1, 2, 4, 2000). Those forms, plus $0 and sub-dollar gross, are the named uncapturable class below: validated by invariants and the differential oracle (same as the interior ladder), not by silently shortening a queue that still claims 15,264.

The spec’s “250,000 cases” target is a case *list*, not a PDOC queue. At 3 seconds per uncached form, that queue does not finish. The adopted split is: **every capturable unique live-edition boundary form goes to PDOC; the interior log-ladder and the uncapturable class do not.**

Grid cells collapse heavily onto PDOC fingerprints; the finished capture count will be at most the distinct-form figure above (smoke already showed cache hits from overlapping forms).

Run conditions

Cases by oracle class

Each grid cell is named with the oracle allowed to validate it. Boundary cells that share a PDOC-visible fingerprint collapse to one form; the queue size is the unique-form count above, not the cell count.

Full slice table: `conformance.json` census.

Corpora

m1-ontario-2026-01

pdoc-bonus-2026

year-projection-2026

t4127-option2-2026

grid-2026.1-pdoc-boundary

grid-2026.1-uncapturable-boundary

grid-2026.1-interior-invariants

Disagreements

Full request / engine / PDOC maps: `conformance.json` corpora[].disagreements.

on-biweekly-2000-bonus-1000

engine and PDOC differ on identically specified bonus inputs

AB-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

AB-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

AB-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

AB-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

AB-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

AB-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

BC-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

BC-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

BC-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

BC-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

BC-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

BC-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

BC-P240-106.55-F1-P1

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

MB-P10-40000.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

MB-P10-40000.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

MB-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

MB-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

MB-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

MB-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

MB-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

MB-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

MB-P24-1958.33-F0-P0

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

MB-P24-1958.33-F1-P1

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

NB-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NB-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NB-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NB-P10-7460.00-F1-P1

M-004 (finding 003): the CPP line differs by one binary64 cent and the tax line follows through K2. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NB-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NB-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NL-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NL-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NL-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NL-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NL-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NL-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NL-P53-842.97-F0-P0

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

NL-P240-930.59-F1-P1

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

NS-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NS-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NS-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NS-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NS-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NS-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NS-P22-2817.78-F0-P0

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

NS-P240-258.29-F1-P1

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

NT-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NT-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NT-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NT-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NT-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NT-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NU-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NU-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NU-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NU-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NU-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NU-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

NU-P240-1077.00-F0-P0

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

NU-P240-310.82-F1-P1

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

ON-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

ON-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

ON-P10-5852.29-F1-P1

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

ON-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

ON-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

ON-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

ON-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

ON-P13-2769.24-F0-P0

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

ON-P13-447.54-F0-P0

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

ON-P13-447.55-F0-P0

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

OutsideCanada-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

OutsideCanada-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

OutsideCanada-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

OutsideCanada-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

OutsideCanada-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

OutsideCanada-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

PE-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

PE-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

PE-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

PE-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

PE-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

PE-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

PE-P240-445.37-F1-P1

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

SK-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

SK-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

SK-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

SK-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

SK-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

SK-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

SK-P12-4544.33-F1-P1

M-003 residual (finding 003): one-cent period tax line. The engine's T/P sits within a tenth of a cent of a half-cent; no published rounding rule we tested reproduces PDOC here (see the hypothesis table). Counts in both rates.

YT-P10-500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

YT-P10-500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

YT-P10-50000.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

YT-P10-50000.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

YT-P10-7460.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

YT-P10-7460.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

YT-P10-8500.00-F0-P0

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

YT-P10-8500.00-F1-P1

M-004 (finding 003): PDOC's period CPP line matches IEEE-754 binary64 arithmetic (inferred from its outputs). The exact decimal product is a half-cent that binary64 holds below the half, so PDOC shows one cent less than T4127 half-up. Matches under rounding_compat: pdoc. Counts in the default-arm rate.

Closed: D-007 biweekly mid-year K2

Vector: on-biweekly-midyear-k2-max (matches under pdoc_observed). Published as M-002. PDOC does not force base_max in the reaching period. That is a fact about PDOC, stated with inversion in findings/001.

Closed 2026-10-22: most of M-003 (finding 003)

Of the 164 one-cent July disagreements, 82 were the CPP line and 82 were tax lines. Three named rules close all but 15 of them, with no free parameter:

1. K2 and K2P are two credits (CPP and EI), each rounded to the cent, as the T1 return computes them. T4127 writes two products but does not say where to round; this matches PDOC. Default arm.
2. Ontario V1 is two surtax lines (20% and 36%), each rounded. Default arm.
3. M-004: PDOC's C matches IEEE-754 binary64 (inferred from its outputs): binary64 arithmetic, then the shortest decimal of that value rounded half-up. rounding_compat: pdoc only; the default arm keeps decimal arithmetic for C (8.925 rounds to 8.93; PDOC shows 8.92).

The rules were chosen by inspecting the full corpus; 15 cases remain unexplained. The integer binary64 emulator is differential-tested against hardware floating point on 10 million CPP inputs. findings/003.

Open: M-003 residual

The disagreements left under rounding_compat: pdoc are one-cent period tax lines whose engine T/P sits within a tenth of a cent of a half-cent. No published rounding rule we tested reproduces them; they count in both rates.

Cases where PDOC differs from T4127 decimal

M-004: on an exact decimal half-cent, PDOC's CPP line shows one cent less (8.925 shown as 8.92), consistent with binary64 arithmetic. T4127 decimal arithmetic rounds up. Both are measured and published; PDOC's result is selectable as rounding_compat: pdoc. M-002 remains a selectable k2_method difference.

Coverage gaps

• Quebec / QPIP: EngineError::JurisdictionNotSupported. Never a federal-only T2=0 success. docs/jurisdictions.md.
• Interior log-ladder of grid 2026.1: engine invariants (§16.2 proptests over thirteen jurisdictions) and differential oracle only. Not a per-cell PDOC comparison.
• Uncapturable boundary forms (P ∈ {1,2,4,2000}, $0 and sub-dollar gross): invariants + differential oracle: same as the interior ladder. Live PDOC salary UI cannot enter them.
• Grid PDOC stratum: 9762 distinct capturable July forms (fingerprint-deduped). Queue finished: 8885 match, 97 M-003 1¢ disagreements (counted), 780 PDOC step-2 would not advance (named, not in the rate). Superseded all-14-P count was 15264.
• January-only BC/NL/PE amounts retired from live PDOC: invariants + differential vs July sibling.
• PDOC does not expose Option 2 (cumulative averaging). Live PDOC (observed 2026-06-11, screen WLCM) offers Salary, Commission, Pension, and CPP/EI verification only; there is no Option 2 / S1 / cumulative-averaging control, so no PDOC vectors were captured. Option 2 is a distinct oracle class t4127_worked_examples (T4127 Chapter 5 worked examples plus invariants) with weaker evidence than PDOC. It does not inherit the Option 1 PDOC agreement rate.
• DateBeforeCoverage cells: engine error path, not a PDOC form.
• M-003 PDOC midpoint direction: finding 003 (2026-10-22) named rules for 149 of the 164 one-cent disagreements; 15 remain unexplained and count in both rates; 780 step-2 non-advances named out of the rate; docs/findings/002-pdoc-midpoint-direction.md and docs/findings/003-pdoc-cpp-binary64-and-split-credits.md; rounding_compat pdoc is implemented (ADR-007).
• PDOC bonus class pdoc-bonus-2026: 20 cases captured from live PDOC on 2026-09-19 (locator: Total current bonus payable). Own class; not in the overall Option 1 PDOC rate. One-cent field disagreements are listed on this corpus (same neighbourhood as M-003); expected amounts are PDOC, never the engine.
• Year projection year-projection-2026: oracle class invariants (API tests 22-29). CPP/EI caps, YMPE/CPP2, BC January/July split, federal tax sum vs T1 within P cents, 53-week / 27-biweekly exemptions. Not a PDOC corpus. docs/year-projection.md.

PDOC evidence publication

Ruling (a): JSON cache records are published as a release archive, not in git. PNG screenshots stay local. Their SHA-256 values are recorded here so a missing file cannot stay green only because the report never looked at it.

After download, a stranger can check the claim:

echo 00a68d0bef8835f8271039981c22bcaca54ff5f0786c33fd3c5b346b27a0023f  takehome-conformance-corpus-2026.1.tar.zst | sha256sum -c
tar --zstd -xf takehome-conformance-corpus-2026.1.tar.zst && python3 -c "import json,hashlib,pathlib;h={d['key']:d['screenshotSha256'] for d in (json.loads(p.read_text()) for p in pathlib.Path('records').glob('*.json'))};digest=hashlib.sha256(''.join(f'{k} {h[k]}\n' for k in sorted(h)).encode()).hexdigest();assert digest=='554a54278727bb460e7f2710cde2b6e31b750ea57c4a4ee6735eb2e4d02a71ea'"

M1 screenshot hashes (local PNGs)

M1 measured results (complete corpus)

Ontario 2026-01, twenty vectors, operator manual, PDOC 2026-06-11. All twenty match. See crates/takehome-core/tests/vectors/pdoc_ontario_2026_01.json.

M2 exit checklist

M4 exit checklist

M0 arithmetic canaries

• truncate_exemption_to_cent(3500/12) == 291.66
• Twin: round_contribution_to_cent on the same input is 291.67
• ./scripts/float-ban.sh clean