d042-same-layer-closed-loop-qualification.md

D_042 — Same-Layer SOURCE Closed-Loop / Redundant Path Qualification

Status: limited source-geometry code and code-main Push accepted 2026-11-06 KST. Documentation PR CI/review/merge and docs-main Push acceptance must be recorded in Issue #469; do not make recursive docs PRs. The parent physical-connectivity Issue #12 remains OPEN.

1. Exact bounded SOURCE and scope

Public synthetic fixture d042_local_closed_loop_v94.asc: PADS PowerPCB V9.4 MILS, 254 nm per Canonical Source Tick, Layer 1, NET_A with supported NET_B lexical variant.

The accepted D_041 direct SOURCE bridge spans J0=(200,350) mil to J1=(400,350) mil. Exactly five additional source-owned positive-width straight detour Traces connect J0 to J1 by:

(200,350) → (150,350) → (150,250) → (450,250) → (450,350) → (400,350) mil.

The original 4 SMD Pads and 5 Traces remain. The added 5 detour Traces produce 4 Pad + 10 Trace = 14 local SOURCE geometry Nodes, 14 local candidate Edges, 1 local connected Component, 1 independent local Cycle. A graph traversal and E − V + C confirm the bounded candidate topology. The original 8 D_041 edges remain, with 6 detour attachment/continuation edges; a Net label alone never introduces an edge.

This feature is fixture-specific and exact: it does not qualify arbitrary imported real PCB closed-loop topologies, other layers, curved Copper, global network connectivity, or physical electrical redundancy. A Source-local cycle is not evidence of manufacturer copper continuity, nor a physical Short test.

2. Implementation and protocol

• Rust d042_local_closed_loop.rs reuses D_041 source provenance only after removing the five specifically declared detour records, reparses all 10 Source traces, and checks the complete supported inventory, exact ends, positive width, matching Layer/Net/owner, duplicate/missing segments, public fixture geometry, and graph cycle rank.
• An explicit CLI boardsi-import-artwork --d042-local-closed-loop-v1 produces SHA-256-bound deterministic BOARDSI_D042_LOCAL_CLOSED_LOOP_V1 diagnostic receipt; it is opt-in, not the normal Canonical Solver path.
• Native Qt d042_local_closed_loop_qt.h reads fresh ImportedArtwork and independently rebinds all 10 SOURCE Pin-Pair declarations to exact source-coordinate traces before reconstructing nodes, edges, component and cycle. The Qt decoder requires exact bytewise receipt equivalence with the source SHA. Qt does not accept Rust stdout blindly.
• Successful result explicitly retains P009_UNSUPPORTED, SI_NOT_RUN and GLOBAL_ELECTRICAL_NOT_VERIFIED; its local label LOCAL_COPPER_CLOSED_LOOP_VERIFIED refers only to the declared synthetic SOURCE geometry.

3. Reproducible tests and fail-closed

• Positive: one supported closed loop and two distinct local paths; reproducible deterministic receipt; reversed detour record orientation; NET_A/NET_B; V9.4 supported header variants, tab-delimited Pin-Pair and *SIGNAL*, CRLF; E−V+C=1. Rust source-specific tests 3/3 Debug PASS, 3/3 Release PASS.
• Negative: single Source Tick gap, wrong Net/Layer/width/owner/Pin-Pair, missing or duplicate Trace, displaced Junction/Part, extra/unsupported Section, Via/Area/Arc, stale original Source/SHA, forged edges/cycle/receipt, and header-only Pin-Pair ownership swap. Both Rust and Qt fail closed on unsupported evidence; geometry rejection must not be reinterpreted as an electrical Short.
• Native Qt dedicated runner registered in existing CMake/CTest/Native CI. Existing Linux offscreen 64/64 CTest PASS, including D_042 and previous D_039–D_041; actual existing Native Qt Windows x64, Windows ARM64, macOS ARM64 workflow jobs SUCCESS. No additional workflow/runner/Ruleset or expanded platform matrix.

4. Verified CODE PR and independent acceptance

• Code PR #470 final exact HEAD 9cd97d4bc24deaf0c42a30e5c1a6d3999f1f6365: 34/34 pull_request Check Runs and 11/11 workflows SUCCESS; Rustfmt, Clippy with warnings denied, Debug/Release, and native Linux/Windows x64/Windows ARM64/macOS ARM64 all passed.
• Independent same-final-HEAD Codex Review completed, has_any_findings=false, has_unresolved_findings=false; 0 unresolved inline threads. The initial Rustfmt failure, next Clippy identity-op failure, and two historical Codex P2 findings remain historical failures: (1) wrong Source loaded before forged-cycle test, (2) native Qt accepted swapped Pin-Pair declarations independent of geometry. Both defects were fixed and verified again on the new final HEAD.
• Protected GitHub Verified one-parent Squash commit 932e5bcd872fab20393b01cd46ace71a0c685633, sole parent 51a36f173a3ad785151df30c9635997445dc1eaa, GitHub REST verification.verified=true/reason=valid; exact main ref equality verified.
• Code-main exact commit actual event=push CI: 8/8 Actions Workflows SUCCESS · 28/28 Check Runs SUCCESS, none failed/pending/skipped. Qt Push #42130513630 · Numerical Push #42130513899.

5. Documentation closeout and explicit exclusions

Only this file and docs/development-checklist.md change in the separate Markdown-only docs PR. Stage D bounded checked 62 → 63, total checked 133 → 134, pending unchanged (Stage D 2 / total 122). Existing docs-only classifier must SKIP native compilations before allocating runners, preserving all 17 required status contexts and distinguishing SUCCESS from SKIPPED. Accept the exact final docs HEAD only after independent review and passing required CI; use protected Verified one-parent Squash and verify exact docs-main event=push. Record final immutable evidence and close Issue #469 in the Issue comment, not another docs PR.

NOT_VERIFIED: manufactured Copper/Plated Via barrel continuity, whole-board electrical Open/Short, general multilayer Pad/Via/Plane/Pour/Thermal connectivity, P009/PH-08 actual return path, Physical Scenario/Cache/Reference, RLGC and S-parameter simulation/DC–30 GHz product correctness, formal U01–U48/T01–T54 product U/T acceptance, and final release. The additional single bounded checked item is not a product-completion percentage. Parent Issue #12 remains OPEN.