Authoritative reference for VS Code Copilot customization mechanisms: instructions, prompt files, custom agents, agent skills, MCP servers, hooks, and plugins. Use when deciding which customization type to use, creating new .instructions.md/.prompt.md/.agent.md/SKILL.md/mcp.json files from scratch, or debugging why a customization is not loading. DO NOT USE FOR: routine file edits where the format is already known.
**UTILITY SKILL** — Two-mode context-window management. RUNTIME: artifact compression (full/summarized/minimal) used by orchestrator and codegen agents. AUDIT: post-mortem analysis of Copilot debug logs (token profiling, redundancy + hand-off gap detection) used by 11-Context Optimizer. WHEN: "context optimization", "token budget", "runtime compression", "log parsing". DO NOT USE FOR: infra, IaC code, deployments.
**WORKFLOW SKILL** — Maintains repository documentation accuracy and freshness across the docs site, agent files, and changelog. WHEN: "update docs", "doc gardening", "staleness check", "changelog entry", "repo explanation", "agent change docs", "skill change docs". DO NOT USE FOR: agent definitions (edit `.agent.md` directly), SKILL.md content authoring, site theme/build.
**ANALYSIS SKILL** — Query official Microsoft documentation to understand concepts, find tutorials, and learn how services work. WHEN: "Microsoft Learn", "Azure docs", "quickstart guide", "limits and quotas", "WAF reference", "architecture pattern docs". DO NOT USE FOR: Azure pricing (use azure-pricing MCP).
**ANALYSIS SKILL** — Audit-grade reference for Anthropic Claude and OpenAI GPT-5.5 prompting best practices. WHEN: "claude prompting", "gpt-5.5 prompting", "audit agent", "review prompt", "vendor best practices", "anthropic best practices", "openai prompting". DO NOT USE FOR: routine prompt edits where rules are already known, generic markdown style (markdown.instructions.md).
**UTILITY SKILL** — Machine-readable workflow DAG for the multi-step agent pipeline. Defines node types, edge conditions, gates, and fan-out patterns. WHEN: "orchestrator step routing", "resume from graph", "workflow validation", "workflow DAG", "workflow gate", "fan-out pattern". USE FOR: orchestrator step routing, resume-from-graph, workflow validation. DO NOT USE FOR: Azure infrastructure, code generation, troubleshooting.
**UTILITY SKILL** — Reusable Azure Bicep patterns: hub-spoke, private endpoints, diagnostics, AVM composition. WHEN: "hub-spoke Bicep", "private endpoint module", "diagnostic settings", "AVM Bicep composition". USE FOR: Bicep template design, hub-spoke networking, private endpoint patterns, AVM modules. DO NOT USE FOR: Terraform code (use terraform-patterns), architecture decisions (use azure-adr), troubleshooting, diagram generation (use drawio).
**UTILITY SKILL** — Azure infrastructure defaults: regions, tags, naming (CAF), AVM-first policy, security baseline, unique suffix patterns. WHEN: "Azure naming convention", "CAF naming", "resource tags", "AVM module", "security baseline", "region default". USE FOR: any agent generating or planning Azure resources. DO NOT USE FOR: artifact template structures (use azure-artifacts), pricing lookups (read references/pricing-guidance.md on demand).