Grammar backward selection resolves each emitted tree once (stage 2 of #11741's rewire program)

[gunbai-bot]

What

Stage 2 of the rewire program behind #11741 (option-A ruling; stage 1 is #11784, independent — this branches off main). The formal_production_* grammar lookup family in src/v2/std/grammar.dag was ranks 2–10 of the required floor's within-claim recurrence census with the eval-frame memo retired, and the whole budget_interrupted population (effect_plan_bash_materialize_test, runner_slot_provision, witness_floor_workflow_consolidation, build_artifact_verification).

Selecting a production for an emitted node asks, for every candidate, whether its rhs matches the node; a nonterminal slot asks the same of the slot's child. As a recursion from the root, a child's answer was re-derived once per candidate at every ancestor, and again when the token edges were derived after selection — exponential in depth; the memo made it look linear. std.materialization_ladder rule 1: AuthoredDuplication, prescribed Share.

Now: one EmittedProductionResolution per emitted tree — resolved top-down against the set of left-hand sides the parents' candidates place at each child's slot (exactly the population the old recursion explored), each child visited once; matched per node is the set the old formal_production_matches_emitted_child accepted, slots are the conj positional children's resolutions in order. The unique-match selection, the per-lhs exact selection and the token-edge derivation read the carried resolution. Every existing entry point (formal_production_for_lhs_exact, formal_production_unique_lhs_exact_match, formal_production_unique_emitted_match, derive_grammar_relation_row_node, grammar_relation_row_derived_from_productions, formal_production_matches_lhs_exact_child) keeps its signature and its diagnostics (grammar_relation_production_not_found / …_backward_selection_ambiguous / …_emitted_not_conj / …_conj_slot_missing / …_conj_slot_surplus at the same loci).

Semantics-preserving on its face

By structural induction on the emitted tree: for an atom node the singleton checks are the old code verbatim; for a conj node the rhs walk is the old formal_production_rhs_matches_emitted_conj_step with the nonterminal arm reading resolution_production_for_lhs_exact(slot, lhs) where it read formal_production_for_lhs_exact(productions, lhs, child) — equal by the inductive hypothesis, because the slot is that child's resolution and its matched set is filtered by the same lhs and slot-count test the old fold applied. The root selection and the per-lhs selection then fold identical sets with identical None/One/Many arms. The asked restriction loses nothing: a production whose lhs no parent candidate places at a slot was never a candidate in the old recursion either, and the root and the per-lhs entries ask for all lhs / the one lhs respectively. Executed receipts: every grammar-relation witness in the language modules holds on both trees — typescript_derive_grammar_relation_row_round_trip, verilog_interlock_emission (byte-equality of emitted output through the generic fold, token-spine read-back, production-order invariance), typescript_record_task_translate — and the 110 claims below: 110/110 PASS before and after under both realizations.

Matched before/after on the claims it names — BOTH realizations, per claim

claim_batch --claim-run, six modules (the floor's interrupted population plus the bash fold witnesses), same host; "before" is origin/main, "after" is this head. Memo-on is the required floor's live realization and is the landing condition; memo-retired is the #11741 head.

claim	tier	memo-on before → after (eval_steps)	memo-retired before → after (eval_steps)	base floor run steps (memo-on)
an_active_authorized_required_retiree_is_masked_and_not_deleted	new-witness	93,346 → 113,378	442,059,024 → 1,026,190	23886
an_inactive_slot_with_a_populated_cgroup_is_not_deleted	new-witness	87,039 → 107,071	442,042,190 → 1,009,356	15947
a_permitted_surplus_slot_is_masked_and_not_deleted_on_the_first_pass	new-witness	86,929 → 106,961	442,041,942 → 1,009,108	15797
witness_existence_check_no_mtime	grandfathered	138,149 → 175,986	126,363,815 → 2,439,089	2020
bash_serialization_is_total_at_8_distinct_commands	grandfathered	164,940 → 174,013	14,350,440 → 2,578,136	1753
bash_fold_pipe_three_stage_holds	grandfathered	99,298 → 114,335	10,586,564 → 1,160,356	512
bash_serialization_is_total_at_4_distinct_commands	grandfathered	100,064 → 106,129	7,175,236 → 1,289,084	917
bash_fold_command_arbitrary_grep_triple_holds	grandfathered	55,244 → 67,200	6,974,615 → 487,233	292
bash_build_round_trip_pipe_holds	grandfathered	67,478 → 89,063	4,567,246 → 1,050,502	29434
bash_fold_if_then_pipe_soundness_holds	grandfathered	99,470 → 106,417	4,114,088 → 915,004	341
bash_fold_with_redir_pipe_soundness_holds	grandfathered	83,000 → 89,167	3,612,734 → 673,908	252
bash_fold_pipe_echo_hi_wc_holds	grandfathered	75,725 → 81,347	3,598,616 → 657,665	222
bash_serialization_is_total_at_2_distinct_commands	grandfathered	67,626 → 72,187	3,587,634 → 644,558	499
bash_fold_pipe_and_then_left_holds	grandfathered	95,286 → 101,932	2,817,237 → 830,314	259
bash_fold_if_multi_then_holds	grandfathered	87,593 → 93,461	2,803,003 → 812,922	371
bash_fold_if_true_then_echo_holds	grandfathered	73,863 → 78,997	2,307,950 → 578,279	227
bash_fold_and_or_negation_preserves_posix_grouping_holds	grandfathered	85,479 → 89,286	2,095,823 → 1,069,065	240
bash_serialization_is_total_at_1_distinct_command	grandfathered	51,417 → 55,226	1,793,843 → 322,305	290
bash_fold_command_multi_lit_echo_hi_holds	grandfathered	49,826 → 53,635	1,792,205 → 320,667	138
bash_build_round_trip_command_tier_holds	grandfathered	49,818 → 53,627	1,792,192 → 320,654	21108
bash_fold_direct_serialize_multi_lit_echo_hi_holds	grandfathered	49,452 → 53,261	1,791,823 → 320,285	21338
bash_build_round_trip_and_then_holds	grandfathered	57,232 → 68,646	1,196,063 → 609,227	23265
bash_fold_subshell_nested_and_then_holds	grandfathered	75,838 → 79,302	1,024,688 → 508,430	212
bash_fold_and_then_true_false_holds	grandfathered	69,086 → 72,194	1,011,296 → 493,786	146
bash_fold_or_else_true_false_holds	grandfathered	68,958 → 72,066	1,011,155 → 493,645	180
bash_fold_subshell_multi_stmt_holds	grandfathered	65,011 → 67,651	1,003,690 → 484,122	280
bash_fold_with_redir_redir_to_file_var_holds	grandfathered	62,955 → 65,887	634,351 → 389,922	128
bash_fold_negation_subshell_false_holds	grandfathered	57,148 → 59,397	519,477 → 261,515	182
bash_fold_with_redir_stderr_null_holds	grandfathered	51,881 → 53,976	509,403 → 251,118	100
bash_fold_with_redir_stdout_to_stderr_holds	grandfathered	51,773 → 53,868	509,286 → 251,001	100
bash_fold_with_redir_stdout_and_stderr_null_holds	grandfathered	51,769 → 53,864	509,282 → 250,997	100
bash_fold_subshell_true_holds	grandfathered	51,137 → 53,043	508,492 → 249,334	136
bash_fold_command_arbitrary_lit_quote_escape_holds	grandfathered	44,139 → 45,689	494,900 → 234,490	105
bash_fold_command_single_lit_true_holds	grandfathered	44,089 → 45,639	494,849 → 234,439	70
bash_fold_wrong_production_rejects_oracle_holds	grandfathered	46,285 → 48,448	494,713 → 234,303	17504
bash_fold_direct_serialize_single_lit_true_holds	grandfathered	43,898 → 45,448	494,650 → 234,240	17603
bash_fold_command_arbitrary_var_home_holds	grandfathered	43,853 → 45,409	494,614 → 234,204	111
bash_fold_command_var_ref_x_holds	grandfathered	43,813 → 45,369	494,573 → 234,163	70
bash_fold_direct_serialize_var_ref_x_holds	grandfathered	43,578 → 45,134	494,330 → 233,920	17283
bash_build_round_trip_assign_foo_bar_holds	grandfathered	44,810 → 46,400	194,891 → 256,365	21289
bash_fold_assign_wrong_production_rejects_oracle_holds	grandfathered	44,301 → 47,222	151,816 → 202,700	20186
bash_fold_assign_lit_foo_bar_holds	grandfathered	42,629 → 43,732	139,853 → 155,834	67
bash_fold_assign_lit_quote_escape_holds	grandfathered	42,551 → 43,654	139,766 → 155,747	72
bash_fold_assign_var_x_home_holds	grandfathered	42,266 → 43,369	139,478 → 155,459	72
bash_fold_exit_wrong_production_rejects_oracle_holds	grandfathered	36,191 → 36,860	127,680 → 141,644	17048
bash_build_round_trip_exit_42_holds	grandfathered	35,928 → 36,508	127,678 → 141,642	17023
bash_fold_relation_row_true_witness_holds	grandfathered	10,738 → 12,209	127,027 → 39,472	59
an_unobserved_required_retiree_outside_membership_is_named_as_withheld	new-witness	21,393 → 21,393	37,333 → 37,333	23342
an_observed_host_plans_the_missing_slots	new-witness	15,809 → 15,809	24,003 → 24,003	17829
an_active_surplus_slot_is_never_deleted	new-witness	15,001 → 15,001	21,695 → 21,695	15064
bash_fold_with_redir_wrong_spellings_rejects_oracle_holds	grandfathered	7,751 → 8,300	14,242 → 16,367	6877
bash_fold_exit_code_42_holds	grandfathered	6,030 → 6,377	10,709 → 11,905	41
bash_fold_exit_code_0_holds	grandfathered	5,954 → 6,301	10,627 → 11,823	40
bash_fold_negation_wrong_spellings_rejects_oracle_holds	grandfathered	5,822 → 6,169	10,470 → 11,666	5100
bash_fold_negation_subshell_rawline_holds	grandfathered	5,816 → 6,163	10,464 → 11,660	5093
bash_fold_raw_line_orch_emit_holds	grandfathered	4,299 → 4,633	7,648 → 8,788	3665
bash_fold_raw_line_wrong_spellings_rejects_oracle_holds	grandfathered	4,237 → 4,571	7,582 → 8,722	3671
bash_fold_raw_line_x_eq_holds	grandfathered	4,232 → 4,566	7,577 → 8,717	3665
bash_fold_raw_line_cmdsubst_holds	grandfathered	4,232 → 4,566	7,577 → 8,717	3659
bash_fold_raw_line_paren_holds	grandfathered	4,232 → 4,566	7,577 → 8,717	3665
bash_fold_raw_line_quoted_holds	grandfathered	4,232 → 4,566	7,577 → 8,717	3665
bash_fold_raw_line_mktemp_holds	grandfathered	4,232 → 4,566	7,577 → 8,717	3665
bash_fold_raw_line_trailing_nl_holds	grandfathered	4,232 → 4,566	7,577 → 8,717	3665
the_registration_file_decodes_its_ephemeral_member	new-witness	6,423 → 6,423	7,220 → 7,220	6423
only_the_fabric_host_loses_a_provisioning_target	new-witness	4,265 → 4,265	6,041 → 6,041	7436
a_retired_incarnation_is_owned_and_plans_removal	new-witness	3,572 → 3,572	4,903 → 4,903	3816
the_plan_realizes_removal_through_the_privileged_seam	new-witness	3,531 → 3,531	4,862 → 4,862	3599
witness_provision_plan_extracts_only_upserts	new-witness	2,998 → 2,998	4,180 → 4,180	3042
bash_fold_if_wrong_production_rejects_oracle_holds	grandfathered	2,451 → 9,966	3,452 → 22,898	216
bash_fold_subshell_wrong_production_rejects_oracle_holds	grandfathered	2,447 → 6,327	3,435 → 13,156	125
bash_fold_heredoc_wrong_production_rejects_oracle_holds	grandfathered	2,380 → 3,999	3,393 → 7,071	159
bash_fold_delegated_bundle_fail_closed_holds	grandfathered	2,380 → 3,999	3,393 → 7,071	159
bash_fold_and_then_wrong_production_rejects_oracle_holds	grandfathered	2,378 → 28,396	3,381 → 79,537	135
bash_fold_pipe_wrong_production_rejects_oracle_holds	grandfathered	2,378 → 42,679	3,381 → 150,161	211
bash_fold_env_prefixed_wrong_production_rejects_oracle_holds	grandfathered	2,355 → 3,885	3,355 → 6,323	114
bash_fold_heredoc_wrong_spellings_rejects_oracle_holds	grandfathered	2,777 → 3,357	3,342 → 5,383	2781
bash_fold_with_redir_wrong_production_rejects_oracle_holds	grandfathered	2,330 → 3,771	3,317 → 5,575	79
bash_fold_negation_wrong_production_rejects_oracle_holds	grandfathered	2,331 → 2,638	3,305 → 4,082	54
bash_fold_raw_line_wrong_production_rejects_oracle_holds	grandfathered	2,305 → 2,612	3,279 → 4,056	44
bash_fold_env_prefixed_wrong_spellings_rejects_oracle_holds	grandfathered	1,976 → 2,367	2,374 → 3,768	1980
witness_single_artifact_produces_two_checks	grandfathered	2,088 → 2,088	2,290 → 2,290	2086
witness_srv3_deploy_row_names_its_declared_slots	new-witness	1,851 → 1,851	2,050 → 2,050	5353
witness_membership_reconcile_adds_delta_slots	new-witness	1,625 → 1,625	2,025 → 2,025	1644
witness_srv4_instance_roster_matches_its_declared_count	new-witness	1,860 → 1,860	2,016 → 2,016	5355
the_fabric_slot_is_not_a_provisioning_target	new-witness	1,665 → 1,665	1,745 → 1,745	5399
a_registered_or_active_or_enabled_tree_still_refuses_removal	new-witness	1,012 → 1,012	1,134 → 1,134	1013
witness_floor_covers_both_release_bins	grandfathered	818 → 818	818 → 818	818
witness_runner_count_not_in_installer_argv	new-witness	647 → 647	653 → 653	4569
every_enrolled_host_resolves_and_none_is_unmodeled	new-witness	478 → 478	577 → 577	4684
srv2_resolves_as_refused_and_the_others_as_rows	new-witness	455 → 455	554 → 554	4668
no_deploy_row_out_commits_the_memory_budget	new-witness	399 → 399	549 → 549	4612
host_grammar_round_trips_through_the_allocation_renderer	new-witness	333 → 333	353 → 353	333
a_dead_ephemeral_registration_is_a_retired_incarnation	new-witness	313 → 313	334 → 334	314
an_authored_count_enumerates_exactly_that_many_indexed_names	new-witness	222 → 222	222 → 222	240
witness_enumeration_postcondition_red_on_under_count	new-witness	127 → 127	213 → 213	4263
an_unobserved_host_refuses_instead_of_planning	new-witness	170 → 170	170 → 170	4335
an_active_ephemeral_registration_and_an_unreadable_one_still_refuse	new-witness	104 → 104	105 → 105	105
witness_actions_runner_release_cites_github_digest	new-witness	64 → 64	64 → 64	64
a_name_outside_the_host_grammar_refuses_even_when_dead	new-witness	52 → 52	52 → 52	53
an_unmodeled_host_has_no_deploy_row	new-witness	34 → 34	34 → 34	38
bash_fold_heredoc_holds	grandfathered	30 → 30	30 → 30	30
bash_fold_env_prefixed_lit_t_holds	grandfathered	24 → 24	24 → 24	24
bash_fold_emitted_tree_differs_on_wrong_fixture_holds	grandfathered	3 → 3	3 → 3	105
a_pending_unmasked_standing_still_emits_the_inhibitor	new-witness	93,327 → 113,359	0 → 1,024,766	24047
a_completed_retirement_authorizes_exactly_that_tree_removal	new-witness	15,138 → 15,138	0 → 22,013	15278
a_completed_srv1_surplus_retirement_emits_the_teardown_argv	new-witness	21,424 → 21,424	0 → 37,418	23373
an_unobserved_cgroup_withholds_the_removal_by_name	new-witness	15,090 → 15,090	0 → 21,912	15245
a_completed_receipt_for_another_slot_authorizes_nothing	new-witness	86,967 → 106,999	0 → 1,009,284	15875
a_surplus_slot_outside_the_authorized_scope_is_neither_masked_nor_deleted	new-witness	15,118 → 15,118	0 → 21,875	15233
absent_evidence_emits_neither_mask_nor_removal	new-witness	14,787 → 14,787	0 → 21,071	14730
totals (110 claims)		3,475,905 → 3,886,850	1,541,599,084 → 29,373,304

(a) Memo-on, the live path: 74 of 110 claims do more eval steps, +12% in total (3,475,905 → 3,886,850); the largest single increase is +38k (witness_existence_check_no_mtime, 138k → 176k in claim_batch). No claim approaches its ceiling: the floor's own numbers for these claims are far below claim_batch's (the last column: the floor's cross-claim warm tier serves the bash productions, claim_batch installs no roster), and scaling each claim's base floor cost by its measured ratio puts the highest at ~40% of its line (bash_build_round_trip_pipe_holds, 29,434 → ~39k of 361,500 grandfathered; the new-witness-tier runner_slot_provision claims 15.8–23.9k → ~19–29k of 72,300). The CI floor run on this PR is the authoritative reading of that.

(b) Memo-retired, the win: 1,541,599,084 → 29,373,304 eval steps in total (52×); the runner_slot_provision claims 442M → 1.0M; witness_existence_check_no_mtime 126M → 2.4M; the seven memo-retired claims that timed out on the before run (not in the table) all complete after.

What the +12% memo-on is: the resolution bookkeeping (asked-lhs sets per slot) the old recursion did not carry. A first bottom-up draft (match all productions at every node) measured +64% memo-on and was reworked into this asked-lhs form for that reason. The remaining caller-side duplication — language folds deriving a row per subtree, each re-resolving its subtree (bash_fold_relation_row_witness demanded 3× per row in the trace) — is a consumer carry and is not attempted here.

🤖 Generated with Claude Code

[gunbai-bot]

Additional receipt, measured after opening: the docs-projection regen — the production route that never completed on the memo-retired binary (#11741, >48 min, killed) — completes on this branch with the memo-retired binary in 295 s wall (gunbc run … docs_projection_gate --function regen; base memo-on: ~300 s), and the three projections it writes are byte-identical to the committed ones (git status clean afterwards). The eager data environment's one non-completing declaration, data witness_floor_workflow, was this family: its bash-fold serialization derives grammar-relation rows per subtree, and the memo-retired eager env now adds ~0 s over resolve (265 s with --claim-run, 265 s without). So this stage discharges the regen blocker on #11741's list outright.