feat(prompt-builder): load AGENTS.md from profile home alongside project context (#104640)

[ericmaddox]

What does this PR do?

Resolves #104640.

A profile configured for a specific operational role (reviewer, implementer, domain specialist) often defines an operating contract (how reviews are decided, output formats, persona-specific constraints).

Previously, agent/prompt_builder.py only loaded AGENTS.md from the directory chain between the git root and the session's working directory (_agents_md_directory_chain), and loaded SOUL.md alone from the profile home (HERMES_HOME). As a result, an operating contract placed at <profile home>/AGENTS.md was never loaded into the prompt when working in repositories or directories outside the profile home.

Changes Made

• agent/prompt_builder.py:
  • Added load_profile_agents_md(context_length, home_override) to look for AGENTS.override.md, AGENTS.md, and agents.md in HERMES_HOME (or home_override).
  • Updated build_context_files_prompt() to load profile AGENTS.md alongside project context and SOUL.md, deduplicating if the working directory already loaded identical instructions.
• tests/agent/test_prompt_builder.py:
  • Added unit tests for loading AGENTS.md and AGENTS.override.md from profile home.
  • Added unit tests for loading profile AGENTS.md concurrently with project-level AGENTS.md.
  • Added unit tests for deduplication when cwd matches the profile home.

Related Issue

Fixes #104640

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Checklist

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ and all relevant tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: Windows 11

[alt-glitch]

This was generated by AI during triage.

Related: #66155, #23331 and #52580 are open PRs that also load AGENTS.md from HERMES_HOME, each with different precedence (fallback-only vs global vs profile-first). This PR loads the profile file alongside the cwd chain. Flagging the cluster so a maintainer can settle the precedence model once.