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Copilot CLI — Rules

File format
Markdown
Discovery paths
.github/copilot-instructions.md, AGENTS.md
Global install path
~/.copilot
Syllago install method
Symlink, Direct copy
Symlink support
Yes
Native frontmatter fields
applyTo

Features

How each feature converts to syllago's canonical format. See format conversion for what these statuses mean.

Other features

Behaviors, conventions, and capabilities that aren't tied to a single named field — things like path-based activation, discovery rules, and lifecycle behavior.

FeatureConversionSummary
AGENTS.md InstructionsTranslatedConversion type: TranslatedActively mapped to the target provider’s equivalent field during conversion.Learn more →Copilot reads AGENTS.md (and CLAUDE.md, GEMINI.md) at the repo root as instructions, following the agentsmd/agents.md community standard.
cross_provider_recognitionTranslatedConversion type: TranslatedActively mapped to the target provider’s equivalent field during conversion.Learn more →agents_md_instructions: Copilot CLI reads AGENTS.md files following the multi-provider shared format
hierarchical_loadingTranslatedConversion type: TranslatedActively mapped to the target provider’s equivalent field during conversion.Learn more →Copilot CLI supports repo-wide instructions plus path-specific and personal instruction layers with defined precedence
Repository-Wide Custom InstructionsTranslatedConversion type: TranslatedActively mapped to the target provider’s equivalent field during conversion.Learn more →An always-on .github/copilot-instructions.md at the repo root applies to every request made in that repository's context.
Path-Specific Custom InstructionsEmbeddedConversion type: EmbeddedNo canonical equivalent — appended as prose in a conversion notes block so nothing is silently lost.Learn more →NAME.instructions.md files under .github/instructions/ apply only to requests involving files matching a declared path glob.
Personal (Home Directory) Custom InstructionsEmbeddedConversion type: EmbeddedNo canonical equivalent — appended as prose in a conversion notes block so nothing is silently lost.Learn more →$HOME/.copilot/copilot-instructions.md provides user-scoped instructions; COPILOT_CUSTOM_INSTRUCTIONS_DIRS adds search directories.
--no-custom-instructions CLI FlagNot portableConversion type: Not portableUnique to this provider — can’t be carried across providers.Learn more →The --no-custom-instructions flag disables loading of custom instructions from AGENTS.md and related files for a session, enabling a clean-slate run.

Sources

Source
https://raw.githubusercontent.com/github/docs/main/content/copilot/how-tos/copilot-cli/customize-copilot/add-custom-instructions.md
https://raw.githubusercontent.com/github/docs/main/content/copilot/reference/custom-instructions-support.md
https://raw.githubusercontent.com/github/docs/main/content/copilot/reference/customization-cheat-sheet.md