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APEX

Dev container hygiene

This guide explains how APEX keeps GitHub Copilot Chat context lean in the dev container, and what contributors can do locally when extension-contributed chat customizations inflate every turn.

Extensions can contribute skills, agents, prompts, and chat participants. Inspect what the client actually loads before attributing context size to an extension. The product and Accelerator container configurations can differ by revision.

Repository mitigations

Section titled “Repository mitigations”

User-scope discovery is disabled

Section titled “User-scope discovery is disabled”

The workspace settings disable user-profile customization discovery for this repository:

  • chat.instructionsFilesLocations disables ~/.copilot/instructions and ~/.claude/rules.
  • chat.agentFilesLocations disables ~/.copilot/agents and ~/.claude/agents.
  • chat.agentSkillsLocations disables ~/.copilot/skills and ~/.claude/skills.
  • chat.useClaudeMdFile is set to false because this repository uses AGENTS.md.

The same settings are mirrored into the dev container VS Code customizations. They are workspace-scoped, so personal prompts and instructions still work in other repositories.

The dev container extension list is curated

Section titled “The dev container extension list is curated”

The dev container extension list excludes extensions that contribute heavy Copilot Chat customizations without serving the APEX workflow. The policy is recorded next to the customizations.vscode.extensions array in .devcontainer/devcontainer.json.

Unwanted extension recommendations warn contributors

Section titled “Unwanted extension recommendations warn contributors”

The workspace uses .vscode/extensions.json unwantedRecommendations to flag extensions that commonly add large chat customization payloads:

  • ms-azuretools.vscode-azure-github-copilot: duplicates APEX’s end-to-end agent set.
  • ms-windows-ai-studio: AI Toolkit is not used by the APEX flow.
  • teamsdevapp.vscode-ai-foundry: AI Foundry is not used by the APEX flow.

These entries express unwanted recommendations. They are not proof that an extension is disabled or uninstalled. Inspect the active local and remote extension lists in VS Code.

CI rejects denylisted extensions

Section titled “CI rejects denylisted extensions”

npm run validate:extension-bloat rejects changes that add denylisted extensions to the dev container extension list. The denylist lives in tools/scripts/validate-extension-bloat.mjs.

Borderline extensions can remain as unwantedRecommendations only. That keeps the warning visible without blocking contributors who deliberately need a tool for work outside the APEX flow.

Contributor cleanup

Section titled “Contributor cleanup”

Acknowledge the VS Code dialog

Section titled “Acknowledge the VS Code dialog”

Review the extension’s purpose and active scope before disabling or uninstalling it. Do not assume dismissing a recommendation changes the active extension set.

Remove extensions globally when appropriate

Section titled “Remove extensions globally when appropriate”

To remove flagged extensions from every workspace on your machine, run these commands from your host VS Code environment:

Terminal window
code --uninstall-extension ms-azuretools.vscode-azure-github-copilot
code --uninstall-extension ms-windows-ai-studio
code --uninstall-extension teamsdevapp.vscode-ai-foundry

Reinstall an extension later with code --install-extension <id> if you start using it in another workspace.

Trim user-profile prompt files

Section titled “Trim user-profile prompt files”

Personal *.instructions.md and *.prompt.md files in your VS Code user profile load globally by default. The workspace suppresses them for APEX, but they can still add context in other repositories.

Common locations:

  • Windows: %APPDATA%\Code\User\prompts\
  • macOS: ~/Library/Application Support/Code/User/prompts/
  • Linux: ~/.config/Code/User/prompts/

Inspect what loaded

Section titled “Inspect what loaded”

Right-click in the Copilot Chat view and select Diagnostics. The diagnostics view lists every active agent, skill, instruction, prompt, and hook, including where each one came from.

An older source pin or client listing may still show historical hooks. The owner retired APEX .github/hooks/ runtime hooks in the October 18 migration; do not restore them to match that listing. Do not disable Git Lefthook, pre-commit security checks, CI, MCP servers, or other tooling as a blanket cleanup. Verify the scope of each component. See the retirement record.

Use this when you need to confirm that workspace mitigations are active or when a new extension appears to be adding unexpected context.

Adding dev container extensions

Section titled “Adding dev container extensions”

Before adding an extension to .devcontainer/devcontainer.json, inspect the extension package.json for these contributes keys:

  • chatSkills
  • chatAgents
  • chatPromptFiles
  • chatParticipants

If the extension contributes chat customizations that overlap with APEX’s agent and skill model, prefer a per-developer install. If the extension should be blocked for everyone, update the denylist in tools/scripts/validate-extension-bloat.mjs and document the reason.

Parallel chat retry race

Section titled “Parallel chat retry race”

If a session appears to repeat a request, retain the relevant timestamps, request IDs, and logs. Similar spans alone do not establish duplicate billing, discarded responses, or the cause of a retry. Report observations separately from hypotheses.

When filing an upstream issue, use the Copilot Chat feedback issue template in .github/ISSUE_TEMPLATE/copilot-chat-feedback.md and include the relevant saved telemetry details.

Section titled “Related”