docs(agents): new functionality is written in .t27 only

[gHashTag]

Adds the owner's rule (2026-10-11): new functionality is written in .t27 and run by t27c / t27b; outdated logic outside .t27 is abandoned, not extended. AGENTS.md only, no code.

🤖 Generated with Claude Code

[tri-claw]

Summary by t27-bees

This PR adds a new architectural rule to AGENTS.md stating that all new functionality must be written as .t27 specs executed by t27c/t27b, while existing non-.t27 logic is considered legacy and should not be extended. It also codifies that plumbing may remain in host languages but must not decide rules, concurrency must use the actor model from specs/queen/actors.t27, and t27b runtime claims must be verified by running.

Worth a look

Nothing stood out.

---

_{Read: 1 files, +22 -0, the whole diff. Head c328daf. Model: openai-compatible/nvidia/nemotron-3-ultra-550b-a55b. Commands: @t27-bees review | summary | help | pause | resume. Free for every repository.}