agent-instructions-reader

name	agent-instructions-reader
description	Guidelines for modifying the workspace agent instructions reader in src/agentInstructionsReader.ts. Covers file discovery, AGENTS.md/CLAUDE.md parsing, and injection into the Copilot Chat system prompt.

agent-instructions-reader

agentInstructionsReader.ts discovers and reads agent instruction files (AGENTS.md, CLAUDE.md, etc.) from the workspace and injects them into the Copilot Chat system prompt.

Scope

• src/agentInstructionsReader.ts — file discovery and reading utilities.
• src/copilotChatParticipant.ts — consumer that injects instructions into the system prompt.

Search paths (in priority order)

The reader checks these paths relative to each workspace folder root:

1. AGENTS.md
2. CLAUDE.md
3. .claude/AGENTS.md
4. .claude/CLAUDE.md
5. .github/copilot-instructions.md
6. .cursorrules
7. .ai/agents.md
8. docs/AGENTS.md
9. docs/CLAUDE.md

First match wins per workspace folder. Use readAllAgentInstructions() to collect all matches.

Rules

1. Auto-inject on every chat. When the participant builds the Ollama message list, it calls readAgentInstructions() before the system prompt is finalized. If a file is found, its content is appended to the system prompt with a source header.
2. No caching. Instructions are read fresh on every message so live edits to AGENTS.md take effect immediately.
3. UTF-8 only. Non-UTF-8 files are skipped; no encoding detection.
4. Silent on missing files. If no instruction file exists, the chat proceeds normally with only the base system prompt.
5. Source attribution. formatInstructionsForPrompt() prepends [Instructions from <path>] so the model knows where the context came from.
6. Size limits. The raw file content is injected as-is; very large instruction files will consume context window. There is no automatic truncation yet.

Slash command

/instructions — shows the user which file was found and a 500-character preview of its content.

Common mistakes

• Adding a search path that is too generic (e.g., README.md) — would pollute the system prompt with unrelated content.
• Forgetting that the reader scans all workspace folders in a multi-root workspace.
• Expecting the instructions to persist across VS Code restarts — they are read from disk every time.

Testing

Test by:

1. Creating an AGENTS.md in the workspace root with a short instruction.
2. Typing @manulai hello and confirming the response follows the instruction.
3. Running @manulai /instructions to confirm the file is detected.
4. Renaming the file to CLAUDE.md and confirming it is still found.