[johnml1135]

Retargeted to master. The conformance suite (#480) is deferred until after this release, so this PR no longer stacks on it. Its suite-side commit (removing the harness's --no-memoization flag along with the memo) is held back and will be added to #480 after this merges.

Quick summary

Removes HermitCrab's opt-in analysis-cascade memo; the sequential rule cascade
and MergeEquivalentAnalyses still work exactly as before. Measured as a
package (#490), it cost 28-32% and ~29 GB on Sena for no net speedup on FLEx's
parallel path. Pruning (#474 landed; #491/#494/#519 open) is untouched and is
where the real parse-time wins come from.

Where to look

• AnalysisMergeKey (AnalysisStratumRule.cs L229-318) still distinguishes non-head count and
  per-rule unapplication counts -- pinned by AnalysisMergeKeyTests.cs and MergeEquivalentAnalysesTests.cs.
• FinalTemplateState is part of that key. A non-blocking stratum inherits it from the stratum above,
  so merging two analyses that differ only there can drop a parse; pinned by
  AffixTemplateTests.FinalTemplateInLowerStratum_ParsesWhenUpperAnalysesDifferOnlyInFinalTemplateState.
• Memo plumbing is gone (AnalysisScope.cs, AnalysisStateKey.cs, MemoizedCombinationRuleCascade.cs
  deleted) -- maxDegreeOfParallelism and the sequential cascade are unchanged public API.
• Review guidance dropped the memo-key re-audit language (docs/review/hermitcrab.md and others).
• ParallelCombinationRuleCascade and ParallelPermutationRuleCascade (src/SIL.Machine/Rules) now count
  distinct results toward MaxAlternatives, as the sequential cascades do, so the parallelism setting no longer
  decides whether a parse throws MaxAlternativesExceededException; pinned by RuleCascadeTests.cs.

Validation

• dotnet test tests/SIL.Machine.Morphology.HermitCrab.Tests -- 108 passed, 0 failed.
• dotnet test tests/SIL.Machine.Tests -- 889 passed, 3 skipped, 0 failed.
• dotnet csharpier check . -- 715 files checked, clean.
• pwsh -NoProfile -File scripts/comment-hygiene.ps1 -BaseRef origin/master -- clean.
• git diff origin/master..HEAD --stat -- 20 files, +474/-1478. Beyond the memo removal, production
  code adds FinalTemplateState to AnalysisMergeKey and fixes the parallel cascades' MaxAlternatives
  count; tests add the lost-parse test, merge-key tests, cascade-count tests and single-threaded-vs-parallel
  parity tests.
• ./local_check.sh --agent-strict: comment hygiene clean; the Release build stops at the native SentencePiece
  download on this machine, so the test commands above were run directly.

---

Reading this a year from now

The memo only ran when maxDegreeOfParallelism == 1 and tracing was off. FLEx uses
the default parallelism, so production never executed it. #490's ledger measured
the optimization round as a package: no net speedup, and cross-word memo sharing
was 28-32% slower on Sena and cost ~29 GB of memory. The gains keep coming from
search-space pruning that doesn't need a replay cache: #474 (landed), and #491,
#494, and #519 (open at the time of writing). Those shrink the work instead of
caching it, and they apply on the parallel path FLEx actually uses. The memo was
~1,400 lines of subtle code (ReplayOnto grafting, arrival-count bookkeeping)
whose correctness depended on an unenforced key invariant (#490, "narrowing that
key breaks correctness with no test failure").

What stays, and why

• The public Morpher(..., maxDegreeOfParallelism) parameter and the sequential
  cascade. They are API and still useful without the memo.
• Fix bug in MergeEquivalentAnalyses #493's MergeEquivalentAnalyses fix. It keyed on AnalysisStateKey; that key
  now lives as an internal AnalysisMergeKey in AnalysisStratumRule, covering the
  same dimensions (shape, stratum, syntactic and realizational feature structures,
  non-head count, per-rule unapplication counts, and FinalTemplateState).

Prior measurements (not reproduced by this review round)

These are earlier author measurements from the memo-removal work, not commands run
as part of this pass's validation, and no reproducible artifact for them is checked
into the tree:

• Spot check on 5 real grammars (Sena, Amharic, Indonesian, Mbugwe, Aweti), 5 words
  each, all with at least one parse: analysis multisets (gloss, allomorph identity,
  root index, feature structures) were reported identical between master memo-off
  and this branch in both default and sequential modes, 25/25 match.
• On the 14 words where master memo-on also completed, it was reported no faster
  than this branch's sequential mode (e.g. 3,286 ms memo-on vs 3,122 ms without it;
  412 vs 350 ms; the rest within noise).
• Full-solution run reported as 1,003 passed / 3 skipped / 0 failed.

🤖 Generated with Claude Code

---

This change is 

[codecov-commenter]

Codecov Report

❌ Patch coverage is 82.52427% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.57%. Comparing base (2f70c04) to head (a00aaea).

Files with missing lines	Patch %	Lines
...chine.Morphology.HermitCrab/AnalysisStratumRule.cs	79.31%	8 Missing and 10 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #522      +/-   ##
==========================================
- Coverage   74.57%   74.57%   -0.01%     
==========================================
  Files         456      453       -3     
  Lines       38472    38314     -158     
  Branches     5297     5280      -17     
==========================================
- Hits        28692    28573     -119     
+ Misses       8617     8576      -41     
- Partials     1163     1165       +2     

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[claude]

Review: approve

1. Verdict: approve. a00aaea fixes F15. The rebase onto Prune reduplication matches whose copies cannot agree #519 and Restore analysis of literal rewrites without phonological features #538 needed one test-only change, 9740b96, and adds no new findings.
2. Most important: nothing blocks the merge. RuleCascade.cs:33 now defaults a null comparer, so the parallel cascades no longer depend on the runtime accepting null (F15).
3. Counts: Critical 0, Important 0, Low 0 new.
4. Ran: the compare from c5376ac came back diverged (rebased onto 2f70c04), so I reviewed the whole PR again with /code-review high. It raised six candidates. All of them were pre-existing on master or not supported by the code, so none is posted. dotnet test tests/SIL.Machine.Tests --filter RuleCascadeTests: 3 passed, 0 failed. gh pr checks 522: both Build jobs and the advisory comment-hygiene checks passed; Create NuGet package and claude-review are pending. The advisory check does not stand in for the strict scan.
5. Not verified: the null-comparer path on a .NET Framework runtime, which this environment cannot run. I also did not verify sequential-path performance without the memo; that still rests on the HermitCrab optimization round record: what was tried, and a faster package that is not mergeable #490 measurements in the PR body.

API / framework / parity: no public signature change. RuleCascade (SIL.Machine, netstandard2.0) now replaces a null comparer with EqualityComparer<TData>.Default, so its Comparer property is never null. The parallel cascades' MaxAlternatives counting changed as described in the last round. Target frameworks, packages, and machine.py parity: none verified changed.

Findings: F1 addressed (4f63793); F2 addressed (8987126); F3 withdrawn; F4 addressed (e2579c6); F5 accepted, unverified; F6 addressed (1650c10); F7 addressed (c0fb7d7); F8 addressed (c0fb7d7); F9 addressed (72851b3); F10 addressed (72851b3); F11 addressed (72851b3); F12 addressed (1106397, c5376ac); F13 addressed (d900f0f); F14 addressed (27a22a9); F15 addressed (a00aaea).

Reviewed at a00aaea