docs: shift repo guidance to skills-first workflows

AGENTS.md

@@ -116,6 +116,12 @@ Troubleshoot failures: check test isolation → verify mocks → fix implementat
    - If there is no obvious project doc location, ask before creating a new top-level file
 5. **Commit** — Conventional commits format, comprehensive PR summaries
 
+## Workflow Surface Policy
+
+- `skills/` is the canonical workflow surface.
+- New workflow contributions should land in `skills/` first.
+- `commands/` is a legacy slash-entry compatibility surface and should only be added or updated when a shim is still required for migration or cross-harness parity.
+
 ## Git Workflow
 
 **Commit format:** `<type>: <description>` — Types: feat, fix, refactor, docs, test, chore, perf, ci
@@ -149,6 +155,8 @@ mcp-configs/     — 14 MCP server configurations
 tests/           — Test suite
 ```
 
+`commands/` remains in the repo for compatibility, but the long-term direction is skills-first.
+
 ## Success Metrics
 
 - All tests pass with 80%+ coverage