Merge pull request #100 from Jun025/chore/checker-offspring-orphan-cleanup

[rustjava-checker-offspring-and-orphan-artefacts-cleanup] chore: 09-18 채택분의 호출자 없는 산출물 정리

Author: Jun025

AGENTS.md

@@ -173,6 +173,7 @@ done | /usr/bin/grep -c .
 - Test JVM and interpreter semantics, including class initialization, bytecode execution, and monitor behavior, with compiled Java fixtures under `test-data/src` and expected output under `test-data`, executed by `tests/test_class.rs`.
 - Do not place JVM core behavior tests in the `rustjava-runtime` standard library test tree.
 - **Adding or recompiling a fixture means editing `test-data/class-file-versions.txt` in the same commit.** Every committed `.class` has its version frozen there, and a fixture that is not listed fails the pin — deliberately, since a pin that only covers what it already knows about stops covering anything added later. Run `python3 test-data/src/record-class-file-versions.py` and commit the row next to the fixture; a moved version means look at why before re-recording.
+- **Regenerating a hand-assembled fixture** (`test-data/src/{cp,indy,ldc}/make_*_fixtures.py`) — also run `python3 test-data/src/audit-fixture-single-defect.py` (no JDK, under a second; rc=0 = each fixture is broken in exactly its named way). It is manual like `test-data/src/verify-javac-fixtures.sh`: CI does not run it.
 
 ## Compatibility Sources
 - Implement Java compatibility from public specifications, Javadocs, and observable behavior tests. Do not consult or reproduce OpenJDK or other Java runtime implementation source code; keep the implementation independent to avoid licensing and provenance concerns.

docs/test-data-target-policy.md

@@ -0,0 +1,95 @@
+## [2026-09-25] 09-18 채택분이 남긴 호출자 없는 산출물 정리 (rustjava-checker-offspring-and-orphan-artefacts-cleanup)
+- 무엇을: `scripts/ldc-tag-survey-targets/`(Kotlin·Scala 85줄)와 그 조사 블록을 지웠다. `docs/test-data-target-policy.md` 의 결정 논거는 `test-data/class-file-versions.txt` 머리로 접고 문서를 지웠다. `audit-fixture-single-defect.py` 를 `AGENTS.md` 의 픽스처 재생성 절차에 1줄로 올렸다. `check-merge-dropped-symbols.py` docstring 을 검사 내용·trailer 규칙·종료 코드만 남겨 84줄에서 38줄로 줄였고, 측정 이력은 아래로 옮겼다.
+- 왜: 셋 다 CI·테스트·DoD 어디에서도 부르지 않았다. 정책 문서는 들어오는 참조가 0이었고 같은 논거가 두 곳에 있었다. 검사기 docstring 은 측정 서술이라 09-18 반려 4회 중 3회가 그 수치 정정이었다.
+- 사용자 영향: 없음. 검사 로직·CI 잡은 건드리지 않았다. 감사 스크립트는 JDK 없이 0.8초에 rc=0(검사 18 · 결함 없음 5)이라 지우지 않고 수동 경로에 올렸다.
+
+열린 카드 2장(`2026-09-18-root-fixture-target-decision#p0`·`#p1`)의 `target` 이 지운 `docs/test-data-target-policy.md` 를 가리킨다. 그 결정·재개 조건은 이제 `test-data/class-file-versions.txt` 머리에 있다. 카드 처분은 이 회차 범위가 아니라 그대로 둔다.
+
+### `check-merge-dropped-symbols.py` 에서 옮긴 측정 이력 (원문 그대로)
+
+```text
+Report definitions that were in the branch a merge pulled from, and are not in its result.
+
+What this answers: *did a conflict resolution silently drop one side's work*. That failure is
+invisible to everything else we have, which is why it exists. Measured 2026-09-18 by reconstructing
+the loss on `origin/main` and running every axis against it: the generator ran (rc=0), the
+single-defect auditor passed (23 checks, rc=0), `test_class_format` passed (21), `test_fixture_pins`
+passed (3), `check-dod-ci-parity` passed, `git status` was empty and there was no conflict marker.
+Nothing went red. The only signal was counting names by hand, which is what this does instead.
+
+The real incident: two merges on one PR branch (e53b2142, 514d5b08) each dropped four definitions
+that came from the branch being merged in -- `Pool.fieldref`, `MAKECONCAT_DESCRIPTOR`,
+`make_concat_call_site` and the `LINKED` table. The suite stayed green because the fixtures those
+build are committed bytes, so when the generator lost the code the expected output did not move.
+
+Why it is silent, precisely: the loss is invisible exactly when the dropped names are *consistent
+with each other*. Dropping a slice that something else still calls raises AttributeError and gets
+noticed; dropping a whole feature -- which is what taking one side of a conflict does -- leaves a
+file that parses, runs and agrees with every committed artefact. Both were measured.
+
+Scope: a definition is flagged when it exists in the merge's second parent and not in the merge
+result, looked for in every file that either the merged-in branch or the merge itself changed.
+That second half costs something. Measured by running both filters over one window of 83 merges
+(38b0df38..8c7b473f, the last 200 commits of origin/main at the time): the narrow filter reports
+8 merges / 19 definitions, this one reports 10 / 26. The seven extra definitions come from two
+merges -- 514d5b08 (six) and 37ea5a13 (one) -- and they are not all one kind. Four are the second
+of the two real incidents, restored later and present in the tree today. The other three are the
+class described next. On time: the measurement noise is larger than the difference between the two
+versions -- three independent runs of the narrow filter over this window span 229s to 585s, a factor
+of 2.6, while the gap between the versions in one back-to-back run was 70s over 83 merges, about
+0.8s per merge. So there is no significant increase to report, which is a weaker claim than "no
+slower" and the one the numbers actually support. A pull request carries 0-2 internal merges. The
+price of widening is reading, not waiting.
+
+A branch that deletes or renames a definition main still has goes red on its next base pull, and an
+ordinary refactor then has to carry a trailer to say so. 37ea5a13 is exactly that: it pulled
+origin/main into a branch that had already generalised `at_most_one_bootstrap_methods_attribute`
+into `at_most_one_of_each_single_class_attribute`, and the pull reported the old name as dropped.
+Three of the seven extra definitions are this class, so it is a class and not a corner. "CI only
+looks at origin/main..HEAD" is not a reason to discount it -- that range is precisely where this
+lands, on the next base pull of an open branch.
+
+That deliberately also flags *our* intentional deletions, because from the outside the two
+look identical -- which is the whole difficulty. Saying which is which is a judgement, so it is
+recorded as one, on the merge commit:
+
+    Dropped-from-theirs: method fieldref -- superseded by the new pool builder, see <round>
+
+One trailer per name, a reason after `--`, and both are required. THE NAME MUST BE COPIED FROM THIS
+CHECK'S OWN OUTPUT, character for character -- it is matched literally, so `method fieldref` works
+and `Pool.fieldref` does not, even though the second reads better. Run the check, copy the name it
+prints after the colon, paste it. (An earlier version of this docstring used the prettier form as its
+only worked example, which meant anyone who followed it got no exemption and lost a round.)
+
+The list lives in the merge commit message rather than in a file on purpose: a file accumulates
+entries that outlive the merge they excused and quietly turns the check off, while a trailer can
+only ever excuse the one commit it is written on.
+
+Usage:
+    check-merge-dropped-symbols.py [<range>]     # default: origin/main..HEAD
+
+Exit: 0 nothing dropped, or everything dropped is accounted for by a trailer
+      1 something was dropped and not accounted for
+      2 could not measure -- a git call failed, or the clone is shallow
+
+★ 2 is not a softer 0. Every git call here raises rather than returning nothing, because the one
+failure this check must never produce is a green one: in a shallow clone the second parent's objects
+are absent, every read of it comes back empty, and the old code printed `✓ (0 file(s) examined)` and
+exited 0. Measured on this repository at depth 10: merges that examine 20 files in a full clone
+examined 0 and the whole run was green. A check for a silent loss had a silent pass in it.
+
+`-s ours` merges -- "record these upstream cuts as ancestors" -- drop the whole other side on
+purpose, and one trailer per name would mean hundreds. They use the wildcard form instead:
+
+    Dropped-from-theirs: * -- recorded as a merged ancestor only, our tree is authoritative
+
+There is deliberately no structural exemption for them. The obvious one, "skip a merge whose tree
+equals its first parent's", was written and then removed: it is true of `-s ours` *and* of a
+resolution that took our side wholesale, and the second of those is the exact failure this exists
+to catch. Measured -- with that exemption in place, a synthetic merge that discarded the other
+side's new function passed. So the wholesale case has to be declared rather than inferred.
+
+A squash landing has one parent, so there is nothing for this to compare and it reports nothing.
+That is not a gap: the merges this catches are the base-pulls *inside* a branch, and those are
+checked while the pull request is open, whichever way the branch is eventually landed.
+```