skill: remove machine-specific paths from the real-sky upscaler

[WalksWithASwagger]

Summary

Remove machine-specific runtime and model paths from the real-sky upscaler so its CLI is inspectable and usable on any supported machine.

Context

• Blocked by Normalize and disambiguate Rafiki project skills #315 because that issue moves real-sky-poster to its canonical .agents path.
• Operational gate: pipeline: make agent-ready intake atomic and idempotent #338 must fix the ready-intake race observed on this issue before a maintainer re-arms it.
• Roadmap phase: Phase 1 - polish and stability.
• Relevant files after Normalize and disambiguate Rafiki project skills #315: .agents/skills/real-sky-poster/scripts/upscale.py, .agents/skills/real-sky-poster/SKILL.md, its .claude adapter, and focused CLI tests under tests/skills/real-sky-poster.
• Current behavior: the script defaults to absolute paths under /Users/kk/Code/ComfyUI, and importing it for help can require optional ML packages.
• Desired behavior: callers provide portable paths, help works without the ML runtime, and failures occur clearly before GPU work.

Implementation Notes

• Accept or require an explicit --model path; do not invent another user-specific default.
• Move Torch, Spandrel, and other optional heavyweight imports behind the execution path.
• Validate input and model paths before initializing GPU/model code.
• Preserve the upscale algorithm and output behavior.
• Edit the canonical .agents package and preserve the relative Claude adapter established by Normalize and disambiguate Rafiki project skills #315.

Acceptance Criteria

• No runtime or model default contains /Users/kk/Code/ComfyUI or another machine-specific absolute path.
• --help succeeds without Torch, Spandrel, or model weights installed.
• Missing input and model paths produce concise non-secret errors before GPU initialization.
• The skill documentation uses portable commands with explicit paths.
• Focused CLI tests cover help, missing input, and missing model behavior.
• Existing real-sky tests continue to pass without a provider call or model download.
• The canonical skill and Claude adapter remain valid under the skills doctor.

Tests/Evals

• Add CLI-focused subprocess tests that do not import or install heavyweight ML dependencies.
• Real image-quality comparison remains a manual follow-up and is not required for this portability change.

Verification

• python3 .agents/skills/real-sky-poster/scripts/upscale.py --help
• python3 tests/skills/real-sky-poster/test_sky.py
• Run the new focused CLI test directly.
• python3 -m ruff check .agents/skills/real-sky-poster/scripts/upscale.py tests/skills/real-sky-poster
• ~/.agents/bin/skills-doctor --json --repo "$PWD"

Agent Instructions

• Use branch codex/issue-318-real-sky-portability.
• Do not re-add agent:ready until Normalize and disambiguate Rafiki project skills #315 and pipeline: make agent-ready intake atomic and idempotent #338 are merged and a maintainer clears the false escalation.
• Do not download model weights or run GPU/provider work.
• Keep optional imports lazy and errors free of local environment values.
• Limit the change to this skill and its tests.

Human Checkpoints

• Stop if preserving an implicit machine-specific default is a product requirement.

Out of Scope

• Changing the upscale algorithm or model.
• Downloading weights or adding a model manager.
• GPU integration tests or artwork generation.
• Editing unrelated skills.

Linear

Not applicable. Rafiki delivery is GitHub-only; do not create or update a Linear issue.

[github-actions]

Agentic dev loop started on branch codex/issue-318-skill-remove-machine-specific-paths-from-the-rea with provider noop.

[github-actions]

Agentic dev loop finished without opening a PR. Status: no-pr. Provider: noop.

[github-actions]

Agentic issue quality gate failed: Stop labels present: in-progress