AGENTS.md: Add contribution guidance for AI agents

Document the mailing list workflow and the conventions agents get wrong
most often: recipe-only commit summaries with the sub-layer tag carried in
the email subject as [meta-oe][PATCH x/y], the AI-Generated tag, and the
human contributor's Signed-off-by on commits and recipe patch files.

Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>

AGENTS.md

@@ -0,0 +1,78 @@
+AGENTS.md — Meta OpenEmbedded Layers
+
+Guidance for AI agents working in the `meta-openembedded` repository.
+
+## Making changes
+
+- No web PR workflow. The project use **patches on mailing lists**
+  (openembedded-devel@lists.openembedded.org) tracked via patchwork
+  (https://patchwork.yoctoproject.org/project/oe/list/). Don't assume GitHub PR
+  conventions apply.
+- One Git commit per logical change (e.g., one commit per recipe).
+- Commit message format:
+    - Summary line is prefixed with the recipe name, e.g. `python3-posix-ipc:`.
+      If the commit touches multiple recipes, list them comma separated, e.g.
+      `recipe1,recipe2:`.
+    - Do **not** put the sub-layer tag (e.g. `[meta-oe]`) in the commit summary
+      line; it belongs in the email subject only (see below).
+    - Check `git log --oneline <path>` for the prefix convention already in use.
+    - Body explains what and why the change is. If the commit represents a
+      feature addition, also how it was tested.
+    - Prefer explaining _why_ a change was made over restating what's already
+      visible in the diff, unless the diff is long/hard to follow or the reason
+      for the change isn't known — in those cases, summarize what changed
+      instead.
+    - Be succinct: use as few sentences and lines as possible while still
+      covering what/why/how. Cut restatements, filler, and any detail a reviewer
+      wouldn't need (e.g. exact test-run counts, step-by-step narration). One
+      short paragraph is usually enough; only add a second if a distinct point
+      (e.g. testing) needs it.
+    - The most relevant information about the change should be presented first.
+    - Reference bugs as `[YOCTO #1234]` when applicable.
+    - Use `Reported-by`, `Suggested-by`, `Tested-by`, `Reviewed-by`, `Cc` tags
+      where relevant.
+- Email subject format:
+    - The sub-layer tag comes first, directly followed by the `[PATCH]` tag with
+      no space between them: `[meta-oe][PATCH 1/3] recipe: summary`.
+    - Generate it with
+      `git format-patch --subject-prefix="meta-oe][PATCH" <upstream>`, which
+      yields `[meta-oe][PATCH x/y]`; add `-v2` etc. for rerolls
+      (`[meta-oe][PATCH v2 x/y]`).
+    - Each patch carries the tag of the sub-layer it changes (e.g. `meta-oe`,
+      `meta-python`, `meta-networking`, `meta-gnome`). Prefer one series per
+      sub-layer; if a series spans sub-layers, set the tag per patch.
+
+### AI-generated code
+
+- **Mandatory**: any AI-generated code/commit must add an `AI-Generated:` tag
+  line in the commit message, placed _before_ `Signed-off-by` (if present),
+  naming the tool used, e.g.:
+
+    ```
+    python3-posix-ipc: fix feature probing instead of forcing -lrt
+
+    AI-Generated: Uses Claude Code
+    Signed-off-by: Contributor Name <contributor@example.com>
+    ```
+
+- Also add a code comment or other in-patch indication that the code is
+  AI-generated (recommended, not just the commit tag).
+- **Mandatory**: every commit, and every patch file added to a recipe, must
+  carry the human contributor's `Signed-off-by`, placed after `AI-Generated:`.
+  Use the contributor's identity from `git config user.name`/`user.email` (e.g.
+  `git commit -s`, or `git rebase --signoff <upstream>` for existing commits),
+  never one made up for the AI tool. The sign-off certifies the DCO/Developer's
+  Certificate of Origin on the contributor's behalf, so they must review the
+  change before it is sent.
+- In patch files added to a recipe, the header order is `Upstream-Status:`,
+  `AI-Generated:`, then `Signed-off-by:`, and the `From:` line uses the same
+  identity as the sign-off.
+- Contributor is responsible for confirming the AI tool's terms don't conflict
+  with the project's open source license/IP policy, and that any third-party
+  copyrighted material in the AI output is properly licensed before contributing
+  it. See the Linux Foundation generative AI guidance:
+  https://www.linuxfoundation.org/legal/generative-ai.
+- `Co-authored-by` should be omitted in favor of the `AI-generated` tag.
+
+When in doubt about a convention, grep `git log --oneline <path>` in the target
+repo for precedent before inventing a new style.