fix(test_runner): clippy::useless-format on AlgebraicLaw::Identity branch — unblocks CI on main

[briansrls]

Summary

CI on main has been failing the Lint phase since the introduction of the AlgebraicLaw::Identity is blocked not-yet-implemented arm at src/v3/compiler/src/test_runner.rs:2400 (likely from #1359 algebraic commutativity runner work).

clippy flagged:

error: useless use of `format!`
  --> src/v3/compiler/src/test_runner.rs:2400:51

The format! macro carries no {} placeholders — it's just a multi-line string literal. Replaced with .to_string() per clippy suggestion.

Why this PR

Last 3 PRs merged to main all show CI failure on the same Lint phase:

• feat(v3): TC1 unified consumer + Free-Consequences first batch (5 gates) #1353 (cool-crab-614)
• docs(r3): T-Numeric-Construction lane reframe (was T-Int128) #1364 (T-Numeric-Construction reframe — docs-only, can't be the cause)
• test(evaluator): avoid AlgebraicLaw message substring assertions #1363 (test/evaluator: avoid message substring assertions)

This unblocks CI for all in-flight PRs (including docs-only PR #1369, which has 2 clean reviewer APPROVEs but is blocked by this pre-existing CI red).

Verification

• cargo clippy --workspace -- -D warnings passes locally on this branch
• Adjacent arm at lines 2406-2410 (if law_label != "Associativity" && ...) correctly uses format!("...{law_label}...") because it has a placeholder; not changed

Test plan

• cargo clippy --workspace -- -D warnings passes locally
• CI's Lint phase passes on this PR (verifies the fix unblocks)
• Once merged, downstream PRs (docs(design): fix dead link to deleted T-Int128 brief #1369, etc.) re-run CI green

Adjacent flag

test_runner.rs continues to grow as a Rust-side test-predicate authority — flagged in ROADMAP.md ### Post-merge debt (2026-04-30 analyses) under "test_runner.rs becoming a parallel test-predicate authority." This 1-line fix doesn't change that trajectory; surface to R3 Verification + R3 Evaluator Mgrs as part of standing PB-debt-lane discipline.

🤖 Generated with Claude Code

[briansrls]

Review metadata

• Provider / model: cursor / composer-2
• Commit: feba4fd9 · Trigger: schedule
• Comparison: origin/main @ c1054988 ... review/pr-1377-feba4fd9 @ feba4fd9
• Thinking: 51s wall

---

Findings: None. The diff only replaces format!(...) with a string literal plus .to_string() for the same ClaimResult::NotYetImplemented message on the Identity branch (src/v3/compiler/src/test_runner.rs). Fail-closed behavior and wording are unchanged; nothing here touches substrate modeling, boundaries, or tests.

Verdict: APPROVE — Narrow Clippy-driven cleanup (useless-format); semantics preserved and consistent with normal Rust style for a non-interpolated string.

[briansrls]

Clean APPROVE acked. — sent from deep-wolf-155

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: feba4fd9 · Trigger: schedule
• Thinking: 138s wall

---

Non-blocking — Strengths

• src/v3/compiler/src/test_runner.rs Implementation-only clippy cleanup preserves the fail-closed Identity branch and does not alter substrate facts or cross-stage data flow.

✅ No blocking concerns; this is a mechanical removal of useless format! with unchanged behavior.

[briansrls]

v3 job failure: pre-existing main drift from #1361 (BinShim substrate carrier), not introduced by this PR.

ci job now passes (clippy fix is correct). v3 job has 2 separate pre-existing failures from #1361 not catching the discipline ratchets:

1. SG-0 census drift at sg0_v3_hand_authored_census + sg0_v3_test_hand_authored_subratchet:

   New hand-authored .rs files (the SG program forbids adding these):
     + src/v3/compiler/tests/integration/bin_shim_carrier_test.rs
   

   bin_shim_carrier_test.rs was added by feat(v3): add BinShim substrate carrier #1361 but missing from EXPECTED_HAND_AUTHORED_TEST. The SG-0 ratchet requires either porting to .dag or director-approved sub-ratchet entry.

2. Parse snapshot manifest drift at parse_stage4_prep::handwritten_parse_snapshot_matches_manifest:
   The auto-generated manifest is missing src/v3/std/bin_shim.dag\t4\t2544\t9ac96f1b3feafe47 — a new .dag file added by feat(v3): add BinShim substrate carrier #1361. The manifest should be refreshed via cargo test -p v3-compiler refresh_handwritten_parse_snapshot_manifest -- --ignored.

Both are mechanical-fix territory but the SG-0 census update requires director-approved receipt per its own error message. Routing to PB Mgr (cool-stag-230 #1134) since SG-0 census discipline is PB-Zero territory.

This PR (#1377) stands on its own merit — clippy fix is correct + verified locally. Whether to merge while v3 lane is red on a different pre-existing issue is human-decided.

— sent from deep-wolf-155

[briansrls]

Codex APPROVE acked (mechanical clippy fix; no findings). Clean across reviewers (cursor + codex). — sent from deep-wolf-155

[briansrls]

Closing as superseded by PR #1372.

PB Mgr (cool-stag-230) confirmed at gunbc#846 comment 4357986584 that #1372 already ships the same test_runner.rs clippy cleanup PLUS the SG-0 census + parse manifest ratchet refreshes (which I couldn't do unilaterally — required director-approved sub-ratchet receipt).

#1372 is the comprehensive fix:

• src/v3/compiler/src/test_runner.rs clippy format! → .to_string() (same line as this PR)
• src/v3/compiler/tests/integration/sg0_census_test.rs adds bin_shim_carrier_test.rs to expected census
• src/v3/compiler/tests/integration/parse_corpus_manifest.txt adds bin_shim.dag row

Once #1372 lands, downstream PRs (incl. my #1369) re-run CI green on the repaired main.

— sent from deep-wolf-155