feat(agent): AGENTS.md priority over CLAUDE.md per directory

[iRonin]

Problem

When both AGENTS.md and CLAUDE.md exist in the same directory, compose mode loads both. But users typically want AGENTS.md to be the authoritative agent instructions, with CLAUDE.md as a fallback for directories that don't have AGENTS.md.

Solution

New config option context.agents_priority (default: true):

When enabled, at each directory level during the walk:

• If AGENTS.md exists -> load it, skip CLAUDE.md from that directory
• If AGENTS.md doesn't exist -> load CLAUDE.md if present
• .hermes.md is always loaded regardless (complementary Hermes instructions)

This means users get:

• AGENTS.md where project-specific agent conventions exist
• CLAUDE.md as fallback in dirs without AGENTS.md
• .hermes.md on top as Hermes-specific additions

Config

context:
  agents_priority: true  # default: AGENTS.md wins over CLAUDE.md per dir

Testing

• 135 tests pass, 1 skipped
• Also fixes case-sensitivity bug in _resolve_walk_limit where .lower() broke path matching on macOS (/T/ vs /t/)

[teknium1]

Thanks for the detailed PR, @iRonin! This is an automated hermes-sweeper review.

After inspecting current main, the core behavior this PR implements — AGENTS.md taking priority over CLAUDE.md — is already present.

Evidence:

• agent/prompt_builder.py lines 1068–1076: build_context_files_prompt uses a chained or: _load_agents_md(cwd_path) or _load_claude_md(cwd_path). First match wins, so AGENTS.md is loaded and CLAUDE.md is skipped whenever AGENTS.md exists in the directory. This is exactly the behavior this PR requests.
• The function _resolve_walk_limit (which the PR's commit message claims to fix a case-sensitivity bug in) does not exist anywhere on current main. This indicates the PR was developed against a branch that includes the cascading walk-up work from feat(agent): cascading context file discovery with pluggable context loaders #10299 and feat(agent): cascading context file discovery with walk-up #10482, which are not yet merged.
• The context.agents_priority config key and "compose mode" scaffolding in this PR have no counterpart on main.

If the intent is to extend this priority logic to multi-directory recursive walks once #10299/#10482 land, please rebase onto those branches and re-open against them. The single-directory case is already handled on main.