fix: cast initial_basis to long in 07_iterative_nqs_dci scripts (fixes #40)

[thc1006]

Summary

Minimal surgical fix for #40: add .long() cast to the basis tensor before passing it as initial_basis in the two affected 07_iterative_nqs_dci scripts.

Closes #40.

Affected files (2)

• experiments/pipelines/07_iterative_nqs_dci/iter_nqs_dci_sqd.py
• experiments/pipelines/07_iterative_nqs_dci/iter_nqs_dci_krylov_classical.py

Diff summary

Each file gets one extra .long() call + a 4-line explanatory comment:

-    basis = pipeline.extract_and_select_basis()
+    # `extract_and_select_basis()` returns float32 (inherited from the
+    # NF trainer's accumulated_basis). `run_hi_nqs_sqd(initial_basis=...)`
+    # requires integer/bool dtype for the binary occupation vectors, so
+    # cast before passing.
+    basis = pipeline.extract_and_select_basis().long()

Total: 10 insertions, 2 deletions across 2 files. No library changes, no API changes.

Why this scope

See issue #40 for the full root-cause analysis. Short version: extract_and_select_basis() returns float32 (cloned from NF trainer's accumulated_basis), but the downstream run_hi_nqs_sqd/run_hi_nqs_skqd strictly validate integer/bool dtype. 008's sister scripts work because expand_basis_via_connections() happens to cast internally; 007 doesn't have that intermediate step.

Two cleaner long-term architectural fixes (cast at the library source, or relax the validator) are noted in the issue as out-of-scope. This PR is the minimum unblocking patch.

Test plan

Manual end-to-end verification on H2/CPU:

• Before fix: both scripts raise ValueError: initial_basis must be integer or bool dtype ... got torch.float32
• After fix:
  • iter_nqs_dci_sqd.py h2 --device cpu → Error 0.0 mHa, 11.88 s
  • iter_nqs_dci_krylov_classical.py h2 --device cpu → Error 0.0 mHa, 9.32 s
• ruff check experiments/pipelines/07_iterative_nqs_dci/ — clean
• ruff format --check — clean
• (Reviewer) Consider whether to also open a follow-up issue/PR for the root-cause library fix (cast in extract_and_select_basis or lenient validator)

Relationship to PR #39

PR #39 (refactor/pipeline-catalog) renames 07_iterative_nqs_dci/ → 007_iterative_nqs_dci/ via git mv. This PR modifies file content (not paths) in 07_iterative_nqs_dci/. The two PRs touch disjoint aspects of the same files, so git's rename detection should handle the rebase cleanly regardless of merge order.

Recommended merge order:

1. Merge this PR first (standalone, off main, no deps)
2. PR refactor: pipeline catalog with 3-digit prefix + 010-013 method-as-pipeline entries #39 rebases on main (picks up this fix at the old path, then renames folder)
3. OR merge PR refactor: pipeline catalog with 3-digit prefix + 010-013 method-as-pipeline entries #39 first — then this PR rebases (git detects rename, applies fix at the new path)

Either order works.

[Copilot]

Pull request overview

Fixes an end-to-end runtime failure in the 07_iterative_nqs_dci experiment scripts by ensuring the NF/DCI-selected basis is cast to an integer dtype before being passed as initial_basis to HI+NQS runners that strictly validate integer/bool occupations.

Changes:

• Cast pipeline.extract_and_select_basis() output to torch.long in iter_nqs_dci_sqd.py before calling run_hi_nqs_sqd(initial_basis=...).
• Cast pipeline.extract_and_select_basis() output to torch.long in iter_nqs_dci_krylov_classical.py before calling run_hi_nqs_skqd(initial_basis=...).
• Add short inline comments documenting the dtype mismatch and why the cast is required.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
experiments/pipelines/07_iterative_nqs_dci/iter_nqs_dci_sqd.py	Cast extracted basis to long so run_hi_nqs_sqd(initial_basis=...) passes dtype validation.
experiments/pipelines/07_iterative_nqs_dci/iter_nqs_dci_krylov_classical.py	Cast extracted basis to long so run_hi_nqs_skqd(initial_basis=...) passes dtype validation.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

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[George930502]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

Verified:

• Both added comments correctly name the downstream runner actually invoked: iter_nqs_dci_krylov_classical.py calls run_hi_nqs_skqd, iter_nqs_dci_sqd.py calls run_hi_nqs_sqd.
• The .long() cast is the correct fix: PipelineConfig.extract_and_select_basis() returns float32 (cloned from accumulated_basis), which is rejected by validate_initial_basis's is_floating_point() check.
• Scope is appropriate. The 08_iterative_nqs_dci_pt2 sibling scripts have the same extract_and_select_basis() pattern but are not affected, because they immediately pass basis through expand_basis_via_connections(), which casts to long at krylov_expand.py line 113.

🤖 Generated with Claude Code

[thc1006]

@copilot resolve the merge conflicts in this pull request make sure follow rela best practice.