[User Story] Portable capsule review with automatic external project runtimes #473

User Story

As a Python repository maintainer, I want SpecFact to discover and prepare my project's runtime automatically, so capsule review analyzes my actual code and dependencies without requiring SpecFact-specific packaging or repository patches.

Problem and verified scope

Addresses #472. Code Review 0.49.85 launches its capsule but ordinary reviews have no consumer runtime handoff; the current reserved import catalog also conflicts with common project packages and pytest policy rejects ordinary plugin controls. The original customer PR remains inaccessible to the implementation identity; customer logs are reported evidence, not an independently reproduced result.

Delivery contract

• Automatically discover and prepare pip/pip-tools, Hatch, uv and Poetry project runtimes, preserving constraints, locks, environment selection, source roots and test configuration.
• Add specfact code review runtime inspect --json, runtime prepare --json, and review --project-config / --project-runtime options.
• Add a local, content-addressed project-runtime-layer-v2 descriptor; preserve v1 and protected PR authority boundaries.
• Separate sealed control code from target dependency and plugin execution; diagnose genuine incompatibility and native-library failures without altering project pins.
• Keep independent static findings when preparation fails, with one root diagnostic and incomplete dependent evidence instead of cascading import findings.
• Validate real collection/execution and normal consumer GitHub Actions without clearing GITHUB_ACTIONS.

Acceptance

1. Pinned Requests (pip), Hatch, Flask (uv), and Poetry checkouts complete applicable analysis and real test slices on non-root Ubuntu 24.04, Python 3.11/3.12/3.13.
2. A clearly labelled reconstruction covers [Bug] Capsule review fails closed on external Hatch projects without project-runtime handoff #472's detached Hatch src layout, third-party/native imports and pytest plugin configuration.
3. Cold preparation, offline warm reuse, descriptor attachment, source immutability, genuine defect detection and corrupt/incompatible runtime rejection are proven.
4. Relevant PRs require the external corpus; the published signed release repeats the same acceptance.
5. Required quality, signature, Requirements, and SpecFact review gates pass; actionable PR findings are fixed.
6. [Bug] Capsule review fails closed on external Hatch projects without project-runtime handoff #472 stays open until its original customer reproduction is verified. A reconstructed fixture does not substitute for that evidence.

OpenSpec and governance

Change: code-review-16-portable-project-runtime.
Branch: codex/feature-code-review-16-portable-project-runtime; PR targets dev.
Parent: Feature #163 under Epic #162. Blocks resolution of #472.
Related baseline only: #466, #459, #175. No open prerequisite has been identified.
Labels: enhancement, module, codebase, openspec, change-proposal. Assignee: djm81. Project: SpecFact CLI #1. Priority: High.

Implementation explicitly authorized on 2026-09-14 (Europe/Berlin). Follow spec → tests → recorded failure → production implementation → passing evidence. Initial platforms are Linux x86-64, CPython 3.11–3.13. Use 90-minute corpus job ceilings and record actual resource cost. Rollback uses reviewed revert and new signed publication; prior release remains affected by #472.