[auto] docs: add reviewer-sourced rules to Copilot instructions (2026-06-22 → 2026-06-29)

Proposed by the [Update Instructions From PR Reviews](.github/workflows/update-instructions-from-pr-reviews.yml) workflow.

**Settings**
- Repo mined: `Azure/azure-dev`
- Range: since `2026-06-22T10:35:05Z` (last-run cache)
- Branch: [`automated/update-instructions-from-pr-reviews` @ b7ec586](https://github.com/Azure/azure-dev/tree/automated/update-instructions-from-pr-reviews)

**Stats**
- Signal ratio: ~85 human reviewer comments kept from ~120 total (bots, acks, short replies dropped)
- Resolved PRs examined: 43 merged PRs (#8629–#8829)

**PR comment themes promoted**

- **Test goroutine safety: t.Fatal / require.NoError must not be called from non-test goroutines** (httptest handlers, sync.Once closures, etc.) — _[#8790](https://github.com/Azure/azure-dev/pull/8790)_
- **Duplicate extension helpers: export from owning package, don't copy function bodies** — _[#8794](https://github.com/Azure/azure-dev/pull/8794), [#8809](https://github.com/Azure/azure-dev/pull/8809)_
- **User-provided path validation: azure.yaml fields must not escape the service directory** — _[#8779](https://github.com/Azure/azure-dev/pull/8779), [#8599](https://github.com/Azure/azure-dev/pull/8599)_
- **Cross-extension test isolation: skip when sibling files absent; add CODEOWNERS for extension functional tests** — _[#8809](https://github.com/Azure/azure-dev/pull/8809), [#8754](https://github.com/Azure/azure-dev/pull/8754)_

> Generated by [Update Instructions From PR Reviews](https://github.com/Azure/azure-dev/actions/runs/28364473783) · 791 AIC · ⌖ 19.6 AIC · ⊞ 36.3K · [◷](https://github.com/search?q=repo%3AAzure%2Fazure-dev+%22gh-aw-workflow-id%3A+update-instructions-from-pr-reviews%22&type=pullrequests)

---

> [!NOTE]
> This was originally intended as a pull request, but GitHub Actions is not permitted to create or approve pull requests in this repository.
> The changes have been pushed to branch `automated/update-instructions-from-pr-reviews`.
>
> **[Click here to create the pull request](https://github.com/Azure/azure-dev/compare/main...automated/update-instructions-from-pr-reviews?expand=1&title=%5Bauto%5D%20docs%3A%20add%20reviewer-sourced%20rules%20to%20Copilot%20instructions%20(2026-06-22%20%E2%86%92%202026-06-29))**

To fix the permissions issue, go to **Settings** → **Actions** → **General** and enable **Allow GitHub Actions to create and approve pull requests**. See also: [gh-aw FAQ](https://github.github.com/gh-aw/reference/faq/#why-is-my-create-pull-request-workflow-failing-with-github-actions-is-not-permitted-to-create-or-approve-pull-requests)

Show patch preview (124 of 124 lines)

```diff
From b7ec586eaa2413a75c6b98903e2df3e1f858e508 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
Date: Mon, 29 Jun 2026 10:18:34 +0000
Subject: [PATCH] docs: add reviewer-sourced rules to Copilot instructions
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Four recurring themes promoted from PR reviews merged since 2026-06-22:

1. go.instructions.md: Test goroutine safety — t.Fatal/require.NoError must
not be called from httptest handler goroutines or other non-test goroutines;
HTTP headers must be set before WriteHeader. (Source: #8790)

2. extensions.instructions.md: Duplicate helper detection — export shared
helpers from the owning package instead of copying function bodies across
extension packages. (Source: #8794, #8809)

3. extensions.instructions.md: User-provided path validation — paths from
azure.yaml fields (instructions, entryPoint, etc.) must be validated to
stay within the expected root directory. (Source: #8779, #8599)

4. extensions.instructions.md: Cross-extension test isolation — tests loading
sibling-extension files must skip when absent; extension functional tests
should have dedicated CODEOWNERS entries. (Source: #8809, #8754)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
.../instructions/extensions.instructions.md | 37 +++++++++++++++++++
.github/instructions/go.instructions.md | 32 ++++++++++++++++
2 files changed, 69 insertions(+)

diff --git a/.github/instructions/extensions.instructions.md b/.github/instructions/extensions.instructions.md
index f46a73d..9fa70ba 100644
--- a/.github/instructions/extensions.instructions.md
+++ b/.github/instructions/extensions.instructions.md
@@ -16,3 +16,40 @@ applyTo:
- Follow extension guidelines in: cli/azd/docs/extensions/extensions-style-guide.md. If the work
violates any of these principles, include a link to the guide so the user can read it and
... (truncated)
```