spec(port): port specs/port/trios-railway/crates/trios-railway-audit/src/event.t27 (Closes #9790)

[dmitrii-f-t27]

Summary

Port gHashTag/trios-railway:crates/trios-railway-audit/src/event.rs (at 8b229e9489ee, 182 lines) as specs/port/trios-railway/crates/trios-railway-audit/src/event.t27 — Roadmap Stage 6 (goal #4548), target t27c gen-rust. Closes #9790.

The original is the AU-02 Neon audit writer: audit_event inserts one row into igla_race_trials and returns the id, never silently swallowing errors (R5), and AuditArtifact::new builds the stdout JSON artifact the hourly watchdog parses without re-querying Neon.

Per the issue's rule ("Port the decision, not the plumbing"), the two listed functions are ported under their names — audit_event as an undefined; transport no test calls, AuditArtifact_new as a tested pure constructor — and the decisions are ported with 6 tests (20 runtime asserts, 0 vacuous), including the original's own four artifact tests:

• gate2_contributes — the Gate-2 contribution rule: this row contributes exactly when bpb < target_bpb, strictly (original line 88; the original's own true-below and false-above tests);
• image_sha_kept_len — the sha kept-length rule: at most the first eight characters, a shorter sha kept whole (original line 85; the original's own truncate and short tests); the slicing itself is the caller's string plumbing;
• the insert shape — four columns (seed, bpb, step, image_sha), returning the id (original lines 129-131);
• the Neon env fallback order — RAILWAY_POSTGRES_URL preferred, the legacy NEON_DATABASE_URL accepted per L-NEON-RENAME (original lines 101-103).

The clock is a parameter the caller passes (the original stamps Utc::now inside).

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: 8/9 tested — only the audit_event transport untested, by design.
• 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: 100 (> 12).
• grep -cE '^\s*(pub )?fn (AuditArtifact_new|audit_event)\(': 2. grep -cE '^\s*test\s+(["|[A-Za-z_])': 6 (≥ 2).
• Boundary: git status --short — exactly this one file. The repo's lefthook pre-commit passed.
• dupe_scan: all 9 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 #9790 port — crates/trios-railway-audit/src/event.rs (gHashTag/trios-railway, at 8b229e9489ee, 182 lines) re-authored as specs/port/trios-railway/crates/trios-railway-audit/src/event.t27. One file, head 34f72ee05, Closes #9790.

What is verified:

• t27c parse OK, spec-status IMPLEMENTED, typecheck 0 errors / 0 warnings, coverage 8/9 (only the audit_event transport untested, by design), t27c test-report 6 tests / 6 pass / 0 FAIL / 0 BLOCKED, 0 vacuous — including the original's own four artifact tests.
• gen → 100 lines, 0 not yet implemented; the 2 required names count exactly 2; 6 test blocks; boundary exactly the one file.
• dupe_scan: all 9 names unique across 2040 specs; bare body scan adds no duplicate group (752/221 unchanged).
• The t27b-native-run artifact of this head (commit 34f72ee, run 38994760063): event.t27 row — reference pass, t27b pass, tests 6, invariants 0, asserts 20, blockers [], detail empty, reference_disagree: [].

CI (head 34f72ee): 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 #9790 auto-closed, and file the 14-step report.

Dmitrii Fedorov (@dmitrii-f-t27)