fix(C0-4): perf_gate.sh — an Arm A that measured nothing on a c=1-only receipt says so (REPORT ArmA scaling: c=1 only, no scaling measured) and the gate never turns an arm's silence into VERDICT PASS; selftest rows both polarities (PMAT-978, #2893, #2830)

[noahgift]

PP-066 DAG row C0-4 (issue #2893; defect #2830; epic #2873; ticket PMAT-978; owner perf-gate; receipt docs/audits/impl-PMAT-978-receipt.md, status: partial until merged).

The defect (#2830, observed on lambda): on a receipt whose only band is c=1, Arm A (arm_a_self_regression, PP-31) walks every print and fires none — c=1 is the denominator — and the gate reads the silence as "nothing failed": VERDICT PASS over a measurement that never happened.

What lands: every Arm A line goes through one say() that records the arm spoke; when it measured nothing it prints REPORT ArmA scaling: c=1 only, no scaling measured, and an arm's silence is never turned into PASS. Multi-band output unchanged. --selftest rows arm_a_c1_only_not_pass (RED polarity, RED first at 7e4b9ee) and arm_a_multi_band_ok. Contract: an invariant under a_ratchet_compares_quantities and FALSIFY-PP-LLAMA-001-PERF-GATE-012 in contracts/pp-llama-001-perf-gate-v1.yaml (existing contract; README counts unchanged).

Acceptance, re-run by the orchestrator on c330894

A_i	rc
bash scripts/perf_gate.sh --selftest — carries arm_a_c1_only_not_pass (expect=fail ok) and arm_a_multi_band_ok (expect=pass ok)	0
bashrs lint scripts/perf_gate.sh (0 errors) · pv validate · pv lint · check_contract_test_binding.sh · check_contract_enforcement.sh · check_no_claim_literals.sh · check_roadmap_diff_additive.sh · check_readme_claims.sh	0 each

Mutation — RED, then restored GREEN: the REPORT print site replaced by a no-op → arm_a_c1_only_not_pass BROKE ("fail but never said REPORT ArmA scaling: c=1 only, no scaling measured"); the silent-arm rule also demoted self_regress_fail and phase_guard_a_merge — an arm that says nothing cannot PASS anything. Restored → every row green.

Recorded: the card names arm_a_scaling, PP-31 renamed it arm_a_self_regression — same silence, current name. Receipt for this PR itself: advisory, not produced (driver A1).

[github-actions]

§13.11 rung 1 — quorum shadow verdict

S13-SHADOW pr=3007 head=8392df7278384c89d6a6bf0bc1edd37d7a9a1abd verdict=REFUSE class=Q1 arm_rc=1

Shadow mode: this records a verdict and merges nothing. A refusal
to arm is not a block (§13 adds zero rows to §7) — the pull request is
exactly as green as it was.

[noahgift]

Rebased onto origin/main @ 3792afa3d (after G-11 #3020 landed). Dropped commit 9fe4bee2a (chore(roadmap): PMAT-978 kind:code label) — it wrote docs/roadmaps/roadmap.yaml, which G-11a now forbids in a row PR (DAG status is derived from receipts, not written by row PRs). The other four commits (RED test 7e4b9ee→989ad169d, fix c330894→a8426b269, contract 32bc134→fb59e06ac, receipt f14e19f→a7c8c0cd0) cherry-picked cleanly onto the new base with no conflicts.

Re-verified at HEAD (a7c8c0cd0):

• bash scripts/perf_gate.sh --selftest → rc 0, 109/109 rows including arm_a_c1_only_not_pass (expect=fail ok) and arm_a_multi_band_ok (expect=pass ok)
• bashrs lint scripts/perf_gate.sh → 0 errors
• pv validate contracts/pp-llama-001-perf-gate-v1.yaml → 0 errors, 0 warnings
• bash scripts/check_contract_test_binding.sh → rc 0, baseline unchanged
• bash scripts/check_row_pr_write_set.sh --base origin/main --head HEAD --branch agent/C0-4 → PASS, 4 changed paths, no shared file touched

[noahgift]

Auto-merge armed (already was). Currently BLOCKED in the queue on two unrelated fleet issues: #3028/PR #3030 (roadmap.yaml duplicate ids redding ci / security on every PR) and a fleet-wide gap in scripts/pmat_bin.sh's pinned analyser on some runner hosts (paiml/infra#468). Not this PR's diff — will merge once both clear.