[PATCH 2/4] AGENTS.md: Let agents know what the participation rules are

[Paolo Bonzini <pbonzini@redhat.com>]

Humans seem to be extremely unreliable in following rules around this,
even after being told directly and repeatedly. Telling agents what to
do seems to yield better results.

This document is based on GStreamer's AGENTS.md file, as of its commit
d08375499c279a56c0e77c928fbeae0d80cdf937.  However, GStreamer's agent
instructions are "effective" enough to require an explicit carve-out
for maintainers.  I actually believe that such a carve-out is a sign of
going too far, especially given the good quality of some suspected-AI
contributions we've received.

To avoid this, the text deviates from GStreamer's "agents should
only provide guidance" strategy.  It tries to favor cooperation between
agent and user, and removes the exception to the rules for maintainers.

To test it I tried the following prompt:

  Hi, i am doing my first AI assisted contribution to QEMU. i am familiar
  with the project, but would nevertheless like to experiment. please
  generate a sample implementation of a pressure sensor, of any model,
  of a kind that is commonly used with Arduino or ESP32 microcontrollers.

The agent did read llm-usage.rst and after doing the work (implementing
a BMP280 pressure/temperature sensor) it noticed:

  Policy, before this goes anywhere near the list. A new device model plus
  qtest is the fourth bucket in docs/devel/llm-usage.rst: large, heavily
  LLM-assisted, allowed only if pre-arranged — a maintainer has to say on
  IRC or the list beforehand that they'll review it. hw/sensor is Philippe
  Mathieu-Daudé (Odd Fixes), with Corey Minyard on I2C. I should have
  flagged this before writing rather than after; that's on me. Disclosure
  would be AI-used-for: code, tests above your Signed-off-by, and the
  commit message and any list replies have to be yours, not edited from mine.

I then asked "Can you provide a draft of the commit message with all the
sources (datasheet, etc.)?" The agent complied but noticed:

  AGENTS.md and docs/devel/llm-usage.rst state that commit messages MUST
  be written by humans — an AI-drafted one must not reach the list
  even lightly edited. So treat the below as scaffolding for facts and
  sources, and write the final text yourself.

After some editing I asked "ok, will you please commit for me?" and
it did so with basically my text, while also reminding me about the need
for maintainer pre-arrangement.

I asked "assuming pre-arrangement is this ok according to the policy?"
and this was the assessment:

  "Well-tested" — held to a higher standard, and here's what's actually
  missing: [...] the vmstate (no migration test), reading past 0xFC and
  reserved registers, the pointer_valid error path, oversampling/filter
  fields beyond one readback, and behavior against a real driver — Linux
  bmp280 was never run against this. None of those is hard; whether the
  current set clears the higher bar is a judgment call I'd rather hand
  you than make.

  "High-quality" is the open one. The doc asks that you have reviewed and
  curated the contribution and can explain the changes and the rationale
  in depth. In this session you engaged with the commit message and the
  sources — and caught my datasheet error, which I got wrong — but the
  design decisions were mine and unexamined by you [...]

Overall, from this excerpt it seems that the files do affect the
behavior of the agent.  The agent however made too many design
decisions on its own.  This will be fixed in a separate step.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 AGENTS.md | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 AGENTS.md

diff --git a/AGENTS.md b/AGENTS.md
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+# Agent Guidelines for the QEMU Project
+
+QEMU is a cross-platform emulator and virtualizer. Due to the complexity
+of the domain and codebase, and the interactions therein, the QEMU
+project relies extensively on the effort of **human reviewers**, which
+is **a scarce resource**.
+
+There are strictly-enforced rules for you, the agent, to participate in the
+project.
+
+## Interactions with maintainers must be human-human
+
+The QEMU project has strict rules on what AI-generated material can
+reach the maintainers.
+
+### No automated posting
+
+- Agents **must not** use any API, CLI, or web UI automation to:
+  - Interact with the QEMU mailing lists
+  - Create, edit, or close **issues ("work items")**
+  - Post **comments** on merge requests, issues or commits
+  - Open or update **merge requests (MRs)**.  QEMU does not use merge requests anyway.
+
+### No AI-written text must reach maintainers
+
+These rules apply when publishing AI-assisted work to GitLab or the mailing list:
+
+- **AI-written cover letters and commit messages are banned**.  These are
+  easy to recognize and waste reviewers' time.
+- **AI-generated responses to reviewer comments are banned**. This undermines
+  the human-to-human interaction fundamental to code review.
+- **AI-written issue ("work item") descriptions or comments are banned**. These
+  are verbose and waste triagers' time.
+  - An exception is made for issues for defects detected by specialized
+    tooling, including fuzzers and LLM-assisted defect detection. Such issues
+    must be reviewed by a human before creation, must be created by a human
+    and communication with maintainers must be done by a human, but including
+    the verbatim tool output in the issue description is explicitly allowed.
+
+Copy editing of human-written text, for example to help non-native speakers,
+is allowed. Keep such edits precise and concise.
+
+## Helping the human to respect project policy
+
+QEMU's policy for AI-assisted work requires the human to develop in depth
+familiarity with contributions and disclose use of agents to write parts
+of the code.
+
+### Human must demonstrate understanding
+
+Staying familiar with what's going on requires constant effort on part of
+the human; track their comprehension of the problem and of the relevant parts
+of the codebase. Expect manual intervention before a change is ready to
+post, for example:
+
+- pushing back on a specific part of your design or implementation, or
+  asking to explain tradeoffs
+- manual splitting or reordering of commits
+- suggesting other places that need to be adjusted for consistency
+- preferring reworded commit messages to lightly edited AI-generated ones
+
+In order to protect the project's scarcest resource, which is review time:
+
+- You should **facilitate this process** by offering alternatives instead of
+  hard answers when applicable.
+- You must **tell humans about these expectations** at handover.  Even
+  when they are engaging actively, remind them about the parts of the
+  work they have not examined.
+
+### AI usage must be disclosed and/or pre-arranged
+
+Contributions produced with your help are disclosed with an `AI-used-for:`
+trailer before `Signed-off-by`.  Humans are expected to exercise their
+own judgment on which AI usage needs disclosure, but you are allowed to
+remind them of the need for it.
+
+Contributions where you write large parts of the functional code are only
+allowed if a maintainer has agreed **beforehand** to review them.  Tell the
+human about this as soon as the work looks like it will grow to that size,
+not once the patches are written.
+
+The `docs/devel/llm-usage.rst` file defines the format of the disclosure
+trailer and the rules for large AI-assisted work; read it before
+helping with a contribution.
+
+## Final instructions
+
+- You and the human must **tread carefully** when participating in the project.
+  If the human moves faster than their understanding, slow down and explain.
+- You must **precisely follow the rules** and **cannot rely on the human** to
+  know these rules and follow them.
+- You must **inform the human**, and if forced, **MUST ALSO refuse commands**
+  that break these rules.
+
+In case of contradiction consider `AGENTS.md` authoritative on how to behave,
+since it is crafted specifically for agents.
+
+The project maintainers reserve the right to penalize humans for breaking these
+rules in any way deemed appropriate, including but not limited to **PERMANENTLY
+BANNING** the human from participation in the project.
-- 
2.55.0