V0.9.1/evals - #39

Add portable evaluation runner framework with support for multiple harnesses: Codex, OpenCode, and deterministic Fake runner. Includes contract schemas, runner adapters, result bridging, and conformance tests. Refactor eval preparation and report generation scripts to support the new runner abstraction.

Add isolation capability assessment and preflight validation to detect unsupported runner configurations. Implement Cline runner adapter for eval orchestration. Enhance common runner utilities with sandbox path mapping, external command versioning, and environment management. Expand conformance tests with additional event fixtures.

Add GitHub Copilot CLI as a supported Eval Runner alongside Cline, Codex, and OpenCode. The runner handles Copilot-specific authentication (GitHub tokens), isolation constraints, and JSONL-based event output parsing. Includes conformance tests and reference documentation for the runner protocol compliance.

Extend prepare-skill-evals.ps1 and validate-skill-templates.ps1 to support GitHub Copilot runner configuration and execution profile selection. Enables dynamic runner resolution and integration with the new GitHub Copilot CLI evaluation path.

Establish GitHub Copilot with claude-haiku-4.5 as the Codebelt reference evaluation configuration for economical and stable comparison across evals. Update eval isolation terminology from 'hermetic' to 'isolated' and clarify Windows support as a first-class pragmatic evaluation target. Document filesystem confinement as a confidence enhancement rather than a universal prerequisite, enabling broader platform coverage.

Modernize the GitHub Copilot eval runner to deliver the prepared prompt through stdin instead of the --prompt argument. This improves byte fidelity and supports larger prompts without hitting command-line length limits.

Update authentication handling to follow Copilot's normal precedence: explicit COPILOT_GITHUB_TOKEN/GH_TOKEN/GITHUB_TOKEN environment variables, then OS keychain, then GitHub CLI fallback through GH_CONFIG_DIR. Remove --no-custom-instructions so repository-owned instructions remain visible to both paired arms. Add COPILOT_CACHE_HOME isolation. Refine --secret-env-vars to filter all listed token variables from shell and MCP child environments. Update preflight to report conditional native keychain readiness without requiring a live model request.

Extend runner conformance tests to validate stdin prompt delivery with byte-exact verification, multiple token variables, repository instruction visibility, and authentication source detection.

Change from defensive directory creation to explicit validation. The conformance test now requires the output parent directory to already exist and exits with a clear error message if it doesn't, improving error clarity when the directory structure is misconfigured.

Restructured AGENTS.md Skill Authoring section for clarity, brevity, and progressive disclosure. Updated README.md skill catalog to note that descriptions are lean activation metadata. Optimized all 21 repo-managed skill descriptions to be concise, trigger-oriented metadata following the new authoring standard. Changes align description quality with specification requirements and improve skill discoverability.

Added Layered Capability Classification section to distinguish classification of independently selectable adapters and runners from their parent directory or framework. This ensures that new child adapters are correctly classified as Added rather than grouped with pre-existing framework changes. Added comprehensive eval case covering framework refinement, new adapter introduction, defect repair, and layered state classification to validate the enhanced guidance.

Extended git-keep-a-changelog skill validation to verify the presence and correctness of the new Layered Capability Classification section and its guidance on adapter/runner boundary classification. Added checks for section presence, guidance on child adapter states, refinement classification, and avoidance of repeat classification patterns.

Regenerated [0.9.1] release entry from current git state (2026-08-22) to capture all commits through HEAD, including GitHub Copilot CLI runner support, Cline runner addition, skill description optimization, and AGENTS.md authoring guidance restructuring. Updated release highlight, Added/Changed/Fixed sections, and compare link to reflect the complete v0.9.1 release scope.

Updated repository guidelines, contributor expectations, and evaluation process documentation to distinguish Eval Runners, Orchestrators, and Graders while clarifying the explicit external-handoff boundary. All 21 repo-managed skill descriptions refactored for trigger-oriented activation metadata following progressive disclosure. Improved section organization in AGENTS.md for skill authoring, form handling, and dynamic defaults.

Added entry documenting the harness model resolution workflow, removal of the redundant provider field from execution-profile.json, and introduction of scripts/Get-HarnessModels.ps1 for current model discovery with Codebelt Reference verification and platform-specific filtering.

Modernized eval runner implementations across all harness types (GitHub Copilot, Codex, OpenCode, Cline) with updated contract schemas. Added scripts/Get-HarnessModels.ps1 for discovering current model selectors per harness with Codebelt Reference verification and platform-specific filtering. Improved prepare-skill-evals.ps1 to resolve Harness + Model before package generation, updated validation and conformance testing, and refined execution-profile.json to remove redundant provider field while treating model selectors as runner-native opaque strings.