refactor: Extract shared hardened gh-runner module

[dwu96]

Context

The codebase has three independent gh-spawning paths (source_providers, code_review_sage, issue_radar), each with its own trusted-binary resolution, minimal-env construction, and spawn-audit exemption. A future hardening fix must be applied in all three places — a missed copy silently keeps the weaker guard.

Proposal

Extract the hardened runner (trusted-binary resolution via _validate_provider_executable + minimal env + SEL audit + timeout handling) and the GitHub URL parser into one shared module (e.g. kiro_crew/github_runner.py). Make _validate_provider_executable a public symbol of that module. Have source_providers, code_review_sage, and issue_radar all import it — collapsing three spawn-audit allowlist entries into one.

Current state

Issue Radar (PR #314) imports the private _validate_provider_executable cross-layer; this cross-layer dependency should be resolved by the extraction.

Labels

enhancement, security, tech-debt

[bolichen97]

🤖 Kiro Crew Auto-Pipeline [operator: bolichen97] — claimed for the automated security-batch fix run (2026-08-09). A task spec is being generated; an implementation session will open a PR referencing this issue.

[bolichen97]

🤖 Kiro Crew Auto-Pipeline [operator: bolichen97]

Implementation is up: #2407

kiro_crew/github_runner.py now single-sources the hardened gh runner (trusted-binary resolution, minimal env, SEL-audited spawn chokepoint, URL parsing) for the dashboard PR sidebar, Issue Radar, and Code Review Sage — dissolving the cross-layer private import from PR #314 and collapsing four spawn-audit exemptions into one. Also fixes the drift bugs found while diffing the three copies: sage's pipeline.list_open_prs spawned with the gateway's FULL environment (no env=), and sage's discovery spawns emitted no SEL audit.

Pre-push dual-model review fleet ran (GPT 5.6 Sol + Opus 5); 1 Medium + 4 advisories all addressed before push. Driving the PR to green now.

[bolichen97]

🤖 Kiro Crew Auto-Pipeline [operator: bolichen97]

#2407 is review-ready: readiness: passed, 48 checks green, and all four AI reviewers pass on head 7bd7a78 (GPT 5.6 ✅, Opus 4.8 ✅, Design PASS, UX n/a).

Summary of what landed beyond the extraction itself: the shared runner closed the pre-existing env leak in sage's list_open_prs (full gateway environment reached the gh child), added SEL audit to sage's discovery spawns, unified the override/env/resolver semantics at their strictest, pinned GH_HOST=github.com for Issue Radar, stripped ambient ssh-agent identity from all gh children, and made the spawn audit fail-closed (audit-or-deny invoked event before every spawn). Four spawn-audit exemptions collapsed into one.

Ready for human review + merge.