Finish the test policy cut: the five owner answers to TA1's asks (test policy cut 2)

Owner answers: the five open questions of .github/ISSUE_SPECS/1722-delete-digest-type-size-and-unrun-tests.md
("ASK"), answered by the owner and relayed by root on 2026-10-19. Branch:
codex/batch-test-policy-2, from main at ce714017c (TA1 #1722 / PR #1723), with origin/main
fdb1c44c2 (TA2 #1725) merged in before the gates. Phase B PR 2 (TA3) of the 2026-10 test audit.

The owner answers

1. ASK 1, the last three scalar-oracle pairing tests: option A. Delete them and the test-only
   initial-matrix trace. The oracle's render path stays.
2. ASK 2, math m2 EXP2_DIGEST/LOG2_DIGEST: keep. It stays until Make the compressor's AArch64 release build bit-identical to the browser (LANE-3) #1019 is fixed; the PR that
   fixes Make the compressor's AArch64 release build bit-identical to the browser (LANE-3) #1019 deletes it together with its scripts/lib/aarch64-known-defects.py row.
3. ASK 3, the host-core limiter_linked_session PIN: if G5 already covers the case, delete
   the pin and cite the covering entry; if not, add the case to G5 in the corpus's own way, then
   delete the pin, and point true-peak-limiter MUTATIONS.md row 996-K2 at the new owner.
4. ASK 4, gain_pan_profile phase_profile: delete. Then delete the graph phase-profile probes
   too if only tests or test-support use them.
5. ASK 5, the one-line size_of / byte-count re-derivations inside larger tests: trim (class (b),
   approved). Keep real resource ceilings, allocation counts and ABI layouts. A line that guards a
   relation the product enforces becomes that relation without size_of of an internal type.

Non-goals

• No change to product render paths, ceilings the product enforces, C ABI or browser layouts, wire
  goldens, fuzz targets, randomized differentials, allocation counts, or open-defect reproducers.
• crates/math/tests/m2_lane_identity.rs is not touched (answer 2).

Objective gates

1. cargo fmt --all --check.
2. cargo clippy --locked -p <each touched package> --all-targets --all-features -- -D warnings.
3. cargo test --locked --all-features -p <each touched package>.
4. bash scripts/check-workspace-policy.sh.
5. scripts/run-wasm-gates.sh --without-v8-spill (the G5 wasm leg, for the new corpus case).

Touched packages: builtins-compiler, true-peak-limiter, wasm-gate-corpus, wasm-gates (its G5 test
reads the new case), host-core, graph, rack, console-workload, graph-compiler.

Evidence

Line numbers are the base's (ce714017c for items 1-4, the merged tree be08944b3 for item 5).

Item 1: the scalar-oracle pairing tests (answer 1)

crates/builtins-compiler/src/lib.rs (1,100 lines removed, 12 added), commit "TA3 item 1":

• Deleted tests: actual_scalar_nonadjacent_intervening_observer_error_completes_and_retries,
  actual_scalar_nonadjacent_failed_render_materializes_post_fader_before_error,
  actual_scalar_nonadjacent_ramp_retarget_and_failed_retry_stay_at_original_boundaries (12466-13178).
• Deleted helpers they alone used: render_failed_buffer_result, first_fader_state,
  last_fader_state, first_matrix_state, last_matrix_state, assert_owner_states_match
  (12224-12338).
• Deleted instrumentation (5252-5528): TestOnlyInitialMatrixTrace, EMPTY_INITIAL_MATRIX_TRACE,
  SCALAR_INITIAL_MATRIX_TRACE, record_initial_matrix_state, initial_matrix_state, and with them
  the scalar state trace only those tests read: TestOnlyScalarStateTrace,
  SCALAR_STATE_TRACE_CAPACITY, EMPTY_SCALAR_STATE_TRACE, SCALAR_STATE_TRACE,
  test_only_scalar_state_trace, SCALAR_FADER_STATE_WITNESS, SCALAR_MATRIX_STATE_WITNESS, the
  witness's scalar_fader_words/scalar_matrix_words fields (unread since TA1), the writers
  record_scalar_fader_state, record_scalar_matrix_state, record_scalar_state, scalar_owner_id.
• Deleted plumbing in the oracle: the test_only_owner fields of LiveControlFaderProcessor and
  LiveControlMatrixProcessor and their initializers (7036-7097, 9418-9513), and the fifteen
  record_scalar_* calls of ScalarPairProcessor and ScalarSplitPairProcessor (9632-9910). Each
  .inspect_err(|_| record…)? became ?. The render arithmetic and the remaining witnesses
  (FADER_MATRIX_LIVE_WITNESS, FADER_MATRIX_OUTPUT_WITNESS, owner drops, outer lifetime) are
  unchanged.
• BoundaryVariant::Nonadjacent and NonadjacentOutputConflict (constructed only by the deleted
  tests) and the output-track branch for the latter (11198-11295).
• crates/graph/tests/MUTATIONS.md: a TA3 note after the TA1 note (rows 916-16, 916-17).

Item 2: the m2 digests (answer 2)

No change. The PR that fixes #1019 deletes EXP2_DIGEST/LOG2_DIGEST and the LANE-3 row of
scripts/lib/aarch64-known-defects.py.

Item 3: the linked-limiter session pin (answer 3)

Did G5 cover it? No. G5's owner is tools/wasm-gates/tests/g5_native_corpus.rs
(g5_native_digests_match_pins) and the wasm leg of scripts/run-wasm-gates.sh, over
tools/wasm-gate-corpus. The limiter's delegated cases (crates/true-peak-limiter/src/corpus.rs,
D90_DIGESTS) were five, each one limiter_block call over 1,024 frames with fixed parameters:
dual_mono/noise, maximum/noise, dual_mono/near_nyquist_w_min,
dual_mono/impulse_train_long_lookahead, dual_mono/subnormal_release_flush. None retargets a
parameter, unlinks a pair or re-equals one; limiter_block passes linked = false, and the #990
decision and its gain_linked record live in LimiterCore::process_block, which no case reached.
So a relink on designed agreement (996-K2) could not move any G5 digest.

Added, in the corpus's own way: case 5, maximum/link_unlink_relink
(crates/true-peak-limiter/src/corpus.rs, appended; CASE_COUNT 5 -> 6; run_linked,
LINKED_RETARGETS, fill_linked). It builds the prepared LimiterCore at each width (eight
uniform lanes at a 5 ms lookahead, LinkMode::Maximum), renders eight 128-frame blocks of noise at
+6 to +18 dBFS, and retargets: both channels of every lane at block 3 (a linked ramp), lane 0 left
and lane 7 right at block 4 (unlinks), the other channels equal again at block 5. Pin, generated as
the corpus documents (the scalar-oracle digest g5_native_digests_match_pins prints): 31b09672….
It was identical at Scalar, Simd4 and Simd8 natively and in the wasm simd128 leg
(run-wasm-gates.sh: 153 cases, no mismatch). AArch64 runs it in CI's aarch64-release G5 step;
it was not run on this box. Appending it moves the compressor, builtin-tail and automation blocks up
by one global index; their pins are indexed in their own crates, and the layout test passed.
tools/wasm-gate-corpus/src/lib.rs (LIMITER_CASE_COUNT doc) says so.

Mutants (true-peak-limiter src/lib.rs, one at a time, restored with git checkout), on
g5_native_digests_match_pins:

The control shows the pin is the words of a kernel that never links. M9 and E0 at Simd8 stay
owned by the session test's "equal" and "parts nothing" checks.

Deleted: crates/host-core/src/limiter_linked_session.rs PIN, the SHA-256 over master words
and readings (Sha256Sink, digest), the digest print and the MISO_ENGINE_REPIN_LIMITER_LINKED_SESSION
switch (lines 156, 193-194, 532-695, 763-771). The three tests keep every session check and are
renamed the_hot_console_links_unlinks_and_limits_at_{simd8,simd4,scalar}; the module note says
where the words are owned now. crates/true-peak-limiter/tests/MUTATIONS.md: row 996-K2 points at
the G5 case, and a TA3 section records the table above.

Item 4: the phase profile and its probes (answer 4)

Probe decision: delete. No product code uses them: every probe was cfg(feature = "test-support") (rack) or cfg(any(test, feature = "test-support")) (graph), and their only
consumers were phase_profile, the bus_send_profile example (an ignored-style measurement
instrument that gates nothing), and the probes' own tests.

• tools/console-workload/tests/gain_pan_profile.rs: deleted (504 lines; phase_profile and
  probes_split_the_bank_units_and_move_no_bit, the probes' own gate).
• tools/console-workload/examples/bus_send_profile.rs: deleted (397 lines).
• crates/graph/src/lib.rs: test_only_phase_profile (38-210) and the four probe sites in
  GraphExecutor::render (5879-6004). crates/graph/src/runtime.rs: test_only_unit_phase
  (4582-4610).
• crates/rack/src/lib.rs: test_only_bank_phase_profile (21-188), BankStage::test_only_stage_name
  (575-581), the probe sites in BankChain::run and the scatter paths (3215-3978), and
  ProbedMembers with bank_phase_probes_split_every_scatter_path_and_move_no_bit (7926-8081).
• crates/rack/Cargo.toml: the now empty test-support feature; crates/graph/Cargo.toml:
  test-support = []; scripts/test-test-support-ci.py line 161: rack leaves the expected set.

Item 5: size_of re-derivations (answer 5)

Residual risk

The new G5 case runs the linked limiter body (linked_frame_uniform and the mirrored stores) on
NEON under G5 for the first time, and its pin was not checked on aarch64 here (x86-64-v3 native and
wasm simd128 only). If the required aarch64-release G5 step goes red on
effect/true_peak_limiter/maximum/link_unlink_relink, the first step is to check the arm64 digest
against the scalar oracle; it is not by itself a regression of this change.

Test value

No test is new. The rewritten assertions and the defect each turns red on:

• limiter G5 case 5: a pair that relinks on designed agreement without reset, restore or
  desymmetrize (996-K2), at every width and on every target G5 runs.
• successor_swap counts: a carry clause that moves the wrong number of input, strip or effect
  entries (as the byte formulas did, without the layout).
• effect_control_report_charges_the_producers_the_host_hands_out: a host that admits a charge of
  anything but the producers it hands out.
• a_bus_insert_is_charged_once_in_the_session_estimate: a bus insert charged differently from
  the same track insert.
• the launch-fixture estimate tests: a slot reservation folded twice, or not at all, into the
  estimate rows.

Docs updated

crates/graph/tests/MUTATIONS.md and crates/true-peak-limiter/tests/MUTATIONS.md (TA3 sections),
the module notes of limiter_linked_session.rs and corpus.rs, and the G5 limiter block doc in
tools/wasm-gate-corpus/src/lib.rs. docs/handoffs/, docs/audits/ and artifacts/ are dated
records and were not changed.