Add selected candidate handoff preflight

[SoundBlaster]

Motivation

SpecHarvester P32-T5 now emits refreshed selected candidate handoff evidence for the limited popular-library corpus. SpecPM needs a consumer-side gate before maintainers use that producer evidence for intake review.

Goals

• Add a read-only selected candidate handoff preflight.
• Validate refreshed and legacy SpecHarvester handoff artifacts.
• Keep passing preflight as review evidence only, not registry acceptance.

Changes

• Added specpm producer-bundle preflight-selected-candidate-handoff.
• Added SpecPMSelectedCandidateHandoffPreflightReport.
• Validates identity, schema, authority, selected/deferred counts, preview-only posture, producer preflight/viewer status, evidence digests, source fixture digests, and cupertino.core deferral.
• Accepts both refreshed P32 handoff artifacts and legacy selected handoff proposals.
• Documented the policy in specs, DocC, roadmap/workplan, CLI reference, multi-package intake, producer bundle policy, and self-spec.
• Added regression tests for refreshed success, legacy compatibility, CLI JSON, no-root warning, authority drift, candidate drift, source digest drift, and docs coverage.

Validation

• python3 -m py_compile src/specpm/producer_bundle.py src/specpm/cli.py
• PYTHONPATH=src pytest tests/test_core.py -q -k 'selected_candidate_handoff_preflight'
• PYTHONPATH=src pytest -q
• PYTHONPATH=src ruff check .
• PYTHONPATH=src ruff format --check src tests
• git diff --check
• PYTHONPATH=src python3 -m specpm.cli validate . --json
• make docs-build
• make pages-smoke
• make public-index-generate PUBLIC_INDEX_OUTPUT=/tmp/specpm-selected-handoff-preflight-public-index
• PYTHONPATH=src python3 -m specpm.cli producer-bundle preflight-selected-candidate-handoff --body /Users/egor/Development/GitHub/0AL/SpecHarvester/tests/fixtures/refreshed_candidate_layer_selected_handoff/p32-t5-refreshed-candidate-layer-selected-handoff.example.json --root /Users/egor/Development/GitHub/0AL/SpecHarvester --json

Real P32-T5 handoff result: passed, 8 selected candidates, 1 deferred candidate, 3 source digests verified.

Docker note: make dev-reload && make dev-smoke was attempted earlier in the task, but Docker build stalled while loading metadata for docker.io/library/python:3.12-slim; no local specpm:dev image was available. Public index generation and Pages smoke passed.

Boundaries and Non-Goals

• Does not accept packages.
• Does not accept relations.
• Does not seed baselines.
• Does not remove preview_only.
• Does not create a SpecPM pull request.
• Does not publish registry metadata.
• Does not run SpecHarvester or source repository code.

Notes

• This closes the SpecPM-side part of the technical debt found by the limited corpus run: selected producer evidence is now machine-checkable before maintainer intake.

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Filter missing IDs before overlap checks

When a malformed handoff has both a selected and a deferred candidate without id/packageId, candidate_id() returns None, so this intersection includes None; the later ', '.join(overlap) then raises TypeError (and mixed None/string overlaps can also fail in sorted). That makes preflight-selected-candidate-handoff crash instead of returning the already-collected missing-ID validation errors.

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