spec(port): port specs/port/trios-railway/crates/trios-railway-core/src/hash.t27 (Closes #9762)

[dmitrii-f-t27]

Summary

Port gHashTag/trios-railway:crates/trios-railway-core/src/hash.rs (at 8b229e9489ee, 105 lines) as specs/port/trios-railway/crates/trios-railway-core/src/hash.t27 — Roadmap Stage 6 (goal #4548), target t27c gen-rust. Closes #9762.

The original seals the R7 audit triplet RAIL=<verb> @ project=<8c> service=<8c> sha=<8c> ts=<rfc3339> over a SHA-256 of the verb, the project id, the optional service id and the token fingerprint — the digest is the first 8 bytes (16 hex chars), and the bearer token itself is never embedded, only its 7-char-class fingerprint (the first 4 bytes of the token's own SHA-256).

Per the issue's rule ("Port the decision, not the plumbing"), the three listed functions are ported under their names as plan-verdict pure functions (the SHA-256 and the clock are the caller's plumbing — no builtin here) with 6 tests (21 runtime asserts, 0 vacuous, 100% function coverage), including the original's own determinism, no-leak and format tests:

• RailwayHash_seal — the content-addressed seal: the input order (verb, project, service only when present, then the fingerprint), the 8-byte digest, deterministic modulo time, never embedding the bearer token;
• RailwayHash_triplet — the audit line's five-field layout with the absent service rendered as -;
• token_fingerprint — the 4-byte, 8-hex-char audit-safe fingerprint that never leaks the token.

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: 11/11 tested (100%) — no transports in this port.
• t27c test-report: 6 tests / 6 pass / 0 FAIL / 0 BLOCKED, 0 vacuous passes.
• t27c gen | grep -c 'not yet implemented': 0; gen | wc -l: 115 (> 12).
• grep -cE '^\s*(pub )?fn (RailwayHash_seal|RailwayHash_triplet|token_fingerprint)\(': 3. grep -cE '^\s*test\s+(["|[A-Za-z_])': 6 (≥ 3).
• Boundary: git status --short — exactly this one file. The repo's lefthook pre-commit passed.
• dupe_scan: all 13 introduced names unique across 2040 specs (checked before the commit); 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 #9762 port — crates/trios-railway-core/src/hash.rs (gHashTag/trios-railway, at 8b229e9489ee, 105 lines) re-authored as specs/port/trios-railway/crates/trios-railway-core/src/hash.t27. One file, head 98d7a140e, Closes #9762.

What is verified:

• t27c parse OK, spec-status IMPLEMENTED, typecheck 0 errors / 0 warnings, coverage 11/11 (100%) — no transports, t27c test-report 6 tests / 6 pass / 0 FAIL / 0 BLOCKED, 0 vacuous — the original's own determinism, no-leak and format tests carried over: the seal's input order (verb, project, service only when present, then the fingerprint), the 8-byte / 16-hex digest, the 4-byte / 8-hex audit-safe fingerprint that never embeds the bearer token, the triplet's five-field layout with the absent service as -, and the 8-char id short form.
• gen → 115 lines, 0 not yet implemented; the 3 required names count exactly 3; 6 test blocks; boundary exactly the one file.
• dupe_scan: all 13 introduced names unique across 2040 specs; the bare body scan adds no duplicate group (752/221 unchanged).
• The t27b-native-run artifact of this head (commit 98d7a14, run 39012996008): hash.t27 row — reference pass, t27b pass, tests 6, invariants 0, asserts 22, blockers [], detail empty, reference_disagree: [].

CI (head 98d7a14): required trio green — validate, check-linked-issue, parse-ratchet — Check L1 TRACEABILITY green (both commits carry their Closes #9762 reference), and Corpus ratchet green after the fix below; 26 checks pass overall, incl. emit-bitexact, t27b-native-linux, t27b-native-macos.

A fix this PR carried: the first head tripped the Corpus ratchet — a type name gaining a second definition: my SealPlan struct already lived in specs/port/scripts/ci/rebuild_evidence.t27, moving the conflicted-type set off its ledger of 110. The second commit (carrying its own Closes #9762) renames it to RailwaySealPlan; the corpus ratchet is green on this head.

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 #9762 auto-closed, and file the 14-step report.

Dmitrii Fedorov (@dmitrii-f-t27)