T8595: add AGENTS.md (#17)

Adds AGENTS.md at repo root and .github/copilot-instructions.md symlink
for GitHub Copilot code review compatibility (per T8595 spec).

🤖 Generated by [robots](https://vyos.io)

2 files changed, 39 insertions, 0 deletions

diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
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+../AGENTS.md
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diff --git a/AGENTS.md b/AGENTS.md
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+# AGENTS.md — `vyos/mirror-canary`
+
+## Project purpose
+
+Canary / test-target repository for the VyOS mirror pipeline (Rollout 1a and beyond). It is the **source side** of the `vyos` → `VyOS-Networks` PR-mirror pair. Its sister repo `VyOS-Networks/mirror-canary` is the mirror destination.
+
+The repo exists solely to validate mirror-pipeline mechanics end-to-end: PR creation, App-token authentication, Mergify coupling, multi-branch backport, conflict detection, and mirror-refusal semantics. It is not a software product.
+
+## Sibling — not a mirror — pair
+
+`vyos/mirror-canary` (source) and `VyOS-Networks/mirror-canary` (destination) form a canary pair. Changes pushed to `vyos/mirror-canary` trigger the central reusable workflow (`vyos/.github/.github/workflows/pr-mirror-repo-sync.yml`) which opens a mirror PR on `VyOS-Networks/mirror-canary`. They are deliberately kept structurally symmetric so the pipeline can be tested without touching production repos.
+
+## Repository layout
+
+```
+README.md          — human notes on canary test scenarios
+tests/             — small text files used as test payloads for each scenario
+```
+
+## Tech stack
+
+- No build system, no language runtime required.
+- Test payloads are plain text files committed to `tests/`.
+- Mirror pipeline: GitHub Actions reusable workflow; Mergify central config (`extends: mergify`) on both sides.
+
+## Default branch and branch conventions
+
+Default branch: `rolling` (plus long-lived `sagitta` and `circinus` for backport testing).
+
+Commit title format: `T<num>: <description>` or `test: <scenario>` for canary test commits.
+
+Do not commit credentials or secrets.
+
+## When to touch this repo
+
+- During mirror-pipeline rollout verification (Rollout 1a / 1b / 2 / 3 / 4 etc.) to smoke-test new pipeline behaviour.
+- To add a new test scenario: create a small file under `tests/`, open a PR, and observe the mirror pipeline's response on `VyOS-Networks/mirror-canary`.
+- Safe to discard test branches after verification; the default branch `rolling` is the durable baseline.