IELR and multi-entry construction profiling

This document closes H005's profiling work without selecting or implementing a new construction algorithm. The machine-readable authority is construction-profile-v1.json, validated by construction-profile-v1.schema.json. It is an internal_local_observation, not release or adoption evidence.

Public profiler

Run the repository-owned and synthetic profiles with:

bundle exec ruby tool/construction_profile.rb \
  --wall-seconds=60 \
  --output=tool/profile/evidence/construction-profile-v1.json
bundle exec rake quality:construction_profile

Third-party observations require a full checkout that the existing public workload manifest can verify. Each checkout must have the exact revision, origin, clean status, grammar digest, and structural baseline:

bundle exec ruby tool/construction_profile.rb \
  --checkout=namae=/path/to/namae \
  --checkout=bcdice_command=/path/to/BCDice \
  --checkout=nokogiri_css=/path/to/nokogiri

Omitting a checkout records its exact registry metadata as not_run; it does not silently profile a cached file or substitute a synthetic grammar.

The artifact separates reconstructible source provenance from host-bound observations. provenance.base_revision is only the Git base: when capture is dirty, every H005 contract path records its observed digest, base-object digest, and base / modified / untracked state. The clean flag is derived from the exact porcelain status; the status, bound-path set, implementation subset, host observation, and measurement policy each have an integrity digest. The evidence file is excluded from the source and implementation digests, so no digest refers to the bytes that contain itself.

The quality gate reconstructs the base objects, requires the base to be an ancestor of the checked revision, verifies current contract bytes against the bound paths, and checks all derived digests and workload/run entry identities. Ruby version and options, kernel, CPU, and other host fields remain explicitly host-bound rather than cross-platform goldens, but their recorded values are validated against environment_observation_sha256 before that observation is excluded from the deterministic structural comparison.

Every construction has an explicit wall-time limit. Exceeding it records the resource and limit. NoMemoryError and SystemStackError are recorded as resource exhaustion. Those results establish only that a bound was observed; they are not negative proofs about the language or algorithm.

Counting contract

The profiler records these structural quantities from the construction that already exists:

not_applicable is reserved for metrics that the selected construction path does not perform, such as canonical-state counts in direct LALR. A metric that would apply but could not be collected because construction timed out or failed is not_measured; failure never masquerades as algorithmic absence.

Elapsed seconds are retained only as host-bound observations. The schema fixes release_gate to false, and the quality gate deliberately removes elapsed values before comparing evidence. Ruby's live-slot counters are neither a peak measurement nor reproducible retained-object accounting, so peak retained objects are truthfully not_measured. The current builders also expose no state budget or portable per-build heap limit; both omissions are explicit in the evidence.

Profiling is opt-in through Builder(profile: true). Ordinary generation does not calculate the additional item/core summaries. Parser tables, conflicts, generated source, runtime ABI, Grammar IR, and Automaton IR are unchanged.

Current observations

Synthetic and real workloads are separate cohorts. All repository grammar revisions and SHA-256 digests come from the public workload registry. The multi-entry diagnostic is the existing representative matrix grammar at the recorded exact revision, not a new language fixture.

The table pairs direct-LALR edge counts with the canonical collection used by current IELR. The multi-entry row reports the shared result; its committed run records also contain isolated LALR and IELR. On this diagnostic all four shared/isolated combinations retain 9 states, 14 final core items, and 20 final lookahead memberships. That bounded synthetic equality is not evidence that a direct multi-entry implementation lacks value on real grammars.

The three public_real identities—Namae, BCDice command, and Nokogiri CSS—are recorded as not_run because no checkout satisfying the public manifest was supplied for this evidence capture. They contribute no state, item, edge, partition, failure, or timing observation. The only measured real workload is the repository's production frontend; it has no unresolved conflict requiring IELR, and current IELR partitions its 456 canonical states back to the same 227 final states as direct LALR.

Decisions

Direct IELR is NO-GO under the current verifier and workload evidence. Direct multi-entry is MORE DATA.

Direct IELR — NO-GO

The threshold is at least two verified representative real grammars that both show a practical canonical-collection cost and require IELR for semantically meaningful conflicts. The current artifact has one measured real grammar, zero real IELR-required conflict cases, and no verified public checkout.

V001 is complete, so the trust-boundary threshold is satisfied. It also establishes a current NO-GO condition: default and strict ielr1 verification both enumerate the full canonical LR(1) collection. A direct builder would therefore not remove canonical scale cost from the current verified workflow, and the verifier does not establish IELR adequacy or split witnesses. Together with no real IELR-required workload, that makes direct IELR unjustified now rather than merely unmeasured.

Evidence that can change the decision must include verified real grammars, material canonical state/item cost or observed exhaustion, meaningful conflicts removed by IELR, a bounded verification plan that does not make full canonical enumeration mandatory, and an owner accepting the specification and maintenance budget. State-count vanity alone is insufficient.

Direct multi-entry — MORE DATA

The threshold is at least two verified real multi-entry grammars plus either an observed construction bound or at least twofold structural overhead in the current shared path relative to an admitted direct plan. The registry contains zero real multi-entry workloads. The existing synthetic matrix exercises both shared and isolated modes, but neither its elapsed time nor its equal state counts justify a production algorithm.

Evidence that can change the decision must add verified real multi-entry grammars, preserve entry dispatch and shared conflict attribution, demonstrate material structural cost, and identify an owner for the semantic and maintenance plan.