spec(port): port specs/port/trios/crates/trios-rainbow-bridge/src/channel.t27 (Closes #9734)

[dmitrii-f-t27]

Summary

Port gHashTag/trios:crates/trios-rainbow-bridge/src/channel.rs (at 8b229e9489ee, 137 lines) as specs/port/trios/crates/trios-rainbow-bridge/src/channel.t27 — Roadmap Stage 6 (goal #4548), target t27c gen-rust. Closes #9734.

The original declares exactly seven colour channels in ROY G BIV order (an eighth variant is forbidden — R7 + ONE SHOT §8, mirrored by the Coq seven_channels_total lemma) and the total function mapping each of the seven payload variants to its one legal channel — a match with no wildcard arm, total and injective on colour.

Per the issue's rule ("Port the decision, not the plumbing"), the one listed function is ported under its name as a tested pure decision, with 4 tests (61 runtime asserts, 0 vacuous, 100% function coverage):

• channel_of_payload — the mapping: claim → red, heartbeat → orange, done → yellow, honey → green, state → blue, violation → indigo, victory → violet (original lines 100-110);
• channel_count / channel_in_order — the canonical ROY G BIV order (Channel::ALL, original lines 33-46), asserted to be exactly seven — the original's own exactly_seven_channels test;
• payload_kind_count / payload_kind_in_order — the seven payload kinds in the sample order of the original's own injectivity test;
• the total-and-injective-on-colour property is proven by a double loop over all 49 ordered pairs, mirroring the original's channel_of_payload_is_total_and_injective_on_colour test;
• the empty answer marks the unreachable eighth variant, mirroring the wildcard-free match.

The language does not compile enum values as arguments or literals, so both enums are modelled by their serde snake_case tags — the shape this series uses for command strings.

Verification (all run live from the worktree root, zig 0.16.0)

• t27c parse: OK. t27c spec-status: IMPLEMENTED. t27c typecheck: 0 errors, 0 warnings.
• t27c coverage: 5/5 tested (100%) — no transports in this port.
• t27c test-report: 4 tests / 4 pass / 0 FAIL / 0 BLOCKED, 0 vacuous passes.
• t27c gen | grep -c 'not yet implemented': 0; gen | wc -l: 131 (> 12).
• grep -cE '^\s*(pub )?fn (channel_of_payload)\(': 1. grep -cE '^\s*test\s+(["|[A-Za-z_])': 4 (≥ 1).
• Boundary: git status --short — exactly this one file. The repo's lefthook pre-commit passed.
• dupe_scan: all 5 names unique across 2040 specs; the bare body scan adds no duplicate group (752 bodies / 221 groups on base, identical with this spec present).

Dmitrii Fedorov (@dmitrii-f-t27)

[dmitrii-f-t27]

@gHashTag Please merge this PR into master via the golden chain — rights on gHashTag/t27 are read-only for me (403), so the merge itself needs your action.

What this is: the #9734 port — crates/trios-rainbow-bridge/src/channel.rs (gHashTag/trios, at 8b229e9489ee, 137 lines) re-authored as specs/port/trios/crates/trios-rainbow-bridge/src/channel.t27. One file, head be081ddcc, Closes #9734.

What is verified:

• t27c parse OK, spec-status IMPLEMENTED, typecheck 0 errors / 0 warnings, coverage 5/5 (100%) — no transports, t27c test-report 4 tests / 4 pass / 0 FAIL / 0 BLOCKED, 0 vacuous (61 runtime asserts), including the original's own exactly_seven_channels test and the total-and-injective-on-colour property proven over all 49 ordered pairs.
• gen → 131 lines, 0 not yet implemented; fn (channel_of_payload)( count 1; 4 test blocks; boundary exactly the one file.
• dupe_scan: all 5 names unique across 2040 specs; bare body scan adds no duplicate group (752/221 unchanged).
• The t27b-native-run artifact of this head (commit be081dd, run 38993399324): channel.t27 row — reference pass, t27b pass, tests 4, invariants 0, asserts 61, blockers [], detail empty, reference_disagree: [].

CI (head be081dd): required trio green — validate, check-linked-issue, parse-ratchet; 26 checks pass overall, incl. emit-bitexact, t27b-native-linux, t27b-native-macos.

The 3 reds are the base-red trio, not this change: cli-tri (the #3324 include_str!), duplicate-bodies (only the known base names), t27b-native-ratchet (the same verdict red the Queen's port PRs carry; this spec's own row is reference pass + t27b pass — the registration debt is the UNLISTED class).

After the merge I will: verify the spec file live on the merge SHA, confirm #9734 auto-closed, and file the 14-step report.

Dmitrii Fedorov (@dmitrii-f-t27)