Epic: harden GitHub artifact download flows against shell policy wrapper trips

[svelderrainruiz]

Summary Agents currently hit a local shell policy wrapper when trying to run certain GitHub artifact download commands during live triage. That turns a simple evidence-collection step into a false blocker and slows down debugging of workflows such as agent-review-policy. This epic treats artifact download as a first-class future-agent surface. The goal is to make artifact retrieval deterministic across the supported shell planes, with a checked-in helper path that avoids wrapper trips and still preserves the security boundary. ## Why now - While investigating the live Copilot gate failure on PR #965, the attempt to download artifacts from run 22872590273 tripped the local shell policy wrapper before the artifacts could be inspected. - Artifact download is part of normal diagnostics work for workflow failures, review gates, and burn-in signals. - Future agents need a supported retrieval path instead of falling back to ad hoc shell experiments that may be blocked before they run. ## Decisions locked by this epic - Artifact download must have a checked-in supported command path for future agents. - The supported path must work on the shell planes this repo documents for agent operation, especially Windows PowerShell and the npm wrapper plane. - The solution should preserve the local shell-policy boundary rather than bypass it with increasingly ad hoc command shapes. - Failure reporting should distinguish policy-wrapper rejection from GitHub/API/download failures. - The repo should document the preferred command surface for downloading run artifacts during live triage. ## Initial delivery slices - [ ] Reproduce and pin the exact command shapes that trip the shell policy wrapper. - [ ] Define the canonical artifact-download helper contract, including inputs for run id, artifact name, and destination. - [ ] Add a checked-in helper that downloads artifacts without tripping the wrapper and emits a deterministic report. - [ ] Add unit seams/tests for wrapper rejection, missing artifacts, auth failures, and successful downloads. - [ ] Document the supported operator/agent workflow for artifact retrieval during live diagnostics. - [ ] Update the relevant troubleshooting/runbook surfaces to reference the helper instead of raw ad hoc commands. ## Acceptance criteria - Future agents can download a named artifact from a workflow run using a documented checked-in helper path. - The helper works without tripping the local shell policy wrapper in the supported shell planes. - Failure reports clearly show whether the problem is wrapper policy, missing artifact, auth, or GitHub download failure. - The repo documentation points future agents to the supported helper instead of raw one-off command strings. ## Non-goals - Weakening or disabling the shell policy wrapper globally. - Treating manual browser downloads as the primary agent path. - Encoding one fragile command shape per shell instead of establishing a stable helper contract.

[svelderrainruiz]

Work is active on upstream PR LabVIEW-Community-CI-CD#975 for the fork mirror of this epic. I also restored the machine-readable upstream pointer on this fork issue so the PR helper now hydrates upstream issue metadata deterministically again (mirrorOf -> LabVIEW-Community-CI-CD#966).