SCH-18 — Seam import failure, dotfile archive rejection, false-positive gate: fixes + verification

Author: phymora. Child of SCH-13. Every claim below was produced by running the artifact on the pinned interpreters, not by reading it. Repo: school-core, branch main, working tree dirty. Evidence for the defects: docs/research/sch13-adversarial-review.md.

Intent

Make the local SmolVM student-execution seam import on the project's pinned interpreter (python 3.12), stop rejecting every real repository worktree at candidate import, and make the verify gate fail — not pass — when a seam module cannot import. No production dispatch enablement; no provider/GitHub writes.

Changes

#	File	Change
1	`student_vm_runner.py:1`	Add `from __future__ import annotations` (fixes BLOCKER 1).
2	`project_verify.yaml:30`	Add gate `core-python-import`: `python3 -c "import student_vm_runner, verifier_vm, model_relay, candidate_pr"` (fixes BLOCKER 2).
3	`student_vm_runner.py:541`	Archive importer now blocks only `..` and `.git`; tracked dotfiles (`.gitignore`/`.gitattributes`/`.gitmodules`) are admitted as inert data (fixes MAJOR 3).
4	`tests/test_student_vm_artifact.py:439`	New test `test_import_accepts_tracked_dotfiles_from_real_base`: real git base tracking all three dotfiles, real `git archive` → guest-style re-tar, import + materialize, assert content parity.
5	`issue_bridge.py:19`	Add `from __future__ import annotations` — same defect class, same change set (`_build_trusted_verification_evidence(verify_result: Any \| None, …)` at module scope). Without it the 3.9 matrix cannot import `issue_bridge` via `tests/conftest.py`.

Dotfile policy — choice and justification (option (a))

Chosen: allow dotfiles as inert data files. Rationale, verified:

git archive of any real base includes tracked dotfiles (student_vm_runner.py:1189), and the guest returns the whole extracted tree (tar -cf - -C /workspace ., student_vm_runner.py:1143). Rejecting them blocks every real repository — including school-core itself, which git ls-files shows tracks .gitignore and .gitmodules.
_apply_artifact_and_commit (student_vm_runner.py:656) re-copies every artifact file from content and runs git add --all (:683), then asserts git ls-files equals the artifact file list (:684-686). Dotfiles are therefore re-materialized from their bytes, not trusted from the archive.
No submodule init is ever run: grep -n submodule across student_vm_runner.py, verifier_vm.py, candidate_manifest.py, candidate_gate.py, candidate_pr.py returns nothing. A tracked .gitmodules is inert data on the host.
.git and .. remain blocked — the traversal/executable-VCS hazards.

Verification (executed)

Acceptance for SCH-18:

python3.12 -c "import student_vm_runner, verifier_vm" succeeds. ✅ Also succeeds on 3.9.6 and 3.11.15 (previously TypeError/NameError).
pytest collection of the four seam files under py3.9/3.11/3.12. ✅ 50 tests collected on each of 3.9.6 / 3.11.15 / 3.12.13 (previously all four ERRORed on collection).
The gate fails when a seam module cannot import. ✅ _discover_commands loads core-python-import; the import command exits 0 on the fixed tree and exits 1 on a non-importable module. compileall exits 0 on that same broken module — the false positive the new gate closes.
Tracked .gitignore/.gitattributes/.gitmodules base imports cleanly and the materialized candidate matches base dotfile content. ✅ test_import_accepts_tracked_dotfiles_from_real_base passes on 3.9.6 and 3.12.13. Before fix 3 the same archive was rejected: BLOCKED: archive member has unsafe path: '.gitattributes'.
No production dispatch enablement; no provider/GitHub writes. ✅ Only the future import, the archive path policy, the gate config, the new test, and the issue_bridge future import changed. No dispatch flag flipped, no provider call added.

Full seam suite: 47 passed, 3 skipped on python 3.12.13 (pinned) and on python 3.9.6. tests/test_issue_bridge.py: 124 passed on 3.12.13 after the issue_bridge fix.

Residual / not claimed

The four seam files and student_vm_runner.py remain untracked in git (??); the fixes are on disk, not committed. Committing/pushing is out of scope for this child.
mypy --strict (gates 3 and 4) was not run here — mypy is not installed on this host; it is provisioned by the flake. Not credited with catching anything.
The real-guest probes (tests/test_student_vm_guest_probes.py) still skip without SCHOOL_CORE_SMOLVM_PACK; not re-run.
Findings 4 and 5 of the SCH-13 review (bundle_sha256 dead field; guest_id regex mismatch) were not in this child's acceptance and remain open.

Verdict

fix-then-ship → verified. All four SCH-18 acceptance criteria reproduced green on the pinned toolchain; the seam imports and runs on every interpreter the project declares.