Add GitHub Models support

.github/workflows/qa.yml

@@ -0,0 +1,33 @@
+name: QA Instructions
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+
+permissions:
+  pull-requests: write
+  models: read
+
+jobs:
+  qa-instructions:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version-file: ".node-version"
+          cache: "npm"
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build
+        run: npm run build
+
+      - name: Generate QA Instructions
+        uses: ./
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}

README.md

@@ -2,10 +2,17 @@
 
 [![CI](https://github.com/slifty/qa-instructions-action/actions/workflows/ci.yml/badge.svg)](https://github.com/slifty/qa-instructions-action/actions/workflows/ci.yml)
 
-A GitHub Action that automatically generates QA testing instructions for pull requests using Claude. On each PR push, it gathers context about the changes and posts (or updates) a comment with structured testing instructions.
+A GitHub Action that automatically generates QA testing instructions for pull requests using AI. On each PR push, it gathers context about the changes and posts (or updates) a comment with structured testing instructions.
+
+Supports two AI providers:
+
+- **GitHub Models** (default) — uses the GitHub Models inference API with your existing `GITHUB_TOKEN`. No API keys or subscriptions required.
+- **Anthropic** — uses the Anthropic API with a Claude model. Requires an API key.
 
 ## Usage
 
+### GitHub Models (default)
+
 ```yaml
 name: QA Instructions
 on:
@@ -14,6 +21,7 @@ on:
 
 permissions:
   pull-requests: write
+  models: read
 
 jobs:
   qa-instructions:
@@ -22,23 +30,59 @@ jobs:
       - uses: slifty/qa-instructions-action@v1
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
-          anthropic-api-key: ${{ secrets.ANTHROPIC_API_KEY }}
 ```
 
 **Requirements:**
 
+- `permissions: models: read` is required for GitHub Models API access
 - `permissions: pull-requests: write` is required for posting PR comments
-- `ANTHROPIC_API_KEY` must be stored as a repository secret
 - The `synchronize` event type triggers on each push, updating the existing comment
 
+### Anthropic
+
+```yaml
+name: QA Instructions
+on:
+  pull_request:
+    types: [opened, synchronize]
+
+permissions:
+  pull-requests: write
+
+jobs:
+  qa-instructions:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: slifty/qa-instructions-action@v1
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          provider: anthropic
+          anthropic-api-key: ${{ secrets.ANTHROPIC_API_KEY }}
+```
+
+**Requirements:**
+
+- `ANTHROPIC_API_KEY` must be stored as a repository secret
+- `permissions: pull-requests: write` is required for posting PR comments
+
 ## Inputs
 
-| Input               | Description                                 | Required | Default                      |
-| ------------------- | ------------------------------------------- | -------- | ---------------------------- |
-| `github-token`      | GitHub token for API access                 | Yes      | `${{ github.token }}`        |
-| `anthropic-api-key` | Anthropic API key for Claude                | Yes      | —                            |
-| `prompt`            | Optional custom instructions for the prompt | No       | `""`                         |
-| `model`             | Claude model to use                         | No       | `claude-sonnet-4-5-20250929` |
+| Input               | Description                                                  | Required | Default               |
+| ------------------- | ------------------------------------------------------------ | -------- | --------------------- |
+| `github-token`      | GitHub token for API access and GitHub Models authentication | Yes      | `${{ github.token }}` |
+| `provider`          | AI provider: `"github-models"` or `"anthropic"`              | No       | `"github-models"`     |
+| `anthropic-api-key` | Anthropic API key (required when provider is `"anthropic"`)  | No       | `""`                  |
+| `prompt`            | Optional custom instructions appended to the prompt          | No       | `""`                  |
+| `model`             | AI model to use (defaults to a provider-appropriate model)   | No       | `""`                  |
+
+### Default models
+
+| Provider        | Default model                |
+| --------------- | ---------------------------- |
+| `github-models` | `openai/gpt-4o`              |
+| `anthropic`     | `claude-sonnet-4-5-20250929` |
+
+You can override the model with any model supported by the chosen provider.
 
 ## Outputs
 
@@ -50,7 +94,7 @@ jobs:
 
 1. Gathers PR context: metadata, diff, changed file contents, repository file tree, and commit history
 2. Builds a structured prompt with tiered truncation to fit within model context limits
-3. Sends the prompt to Claude, which generates QA instructions covering:
+3. Sends the prompt to the configured AI provider, which generates QA instructions covering:
    - Summary of changes
    - Test environment setup
    - Specific test scenarios with steps and expected results

action.yml

@@ -1,21 +1,26 @@
 name: "QA Instructions Action"
-description: "A GitHub Action that generates QA testing instructions for pull requests using Claude"
+description: "A GitHub Action that generates QA testing instructions for pull requests using AI"
 inputs:
   github-token:
-    description: "GitHub token for API access"
+    description: "GitHub token for API access (also used for GitHub Models authentication)"
     required: true
     default: ${{ github.token }}
+  provider:
+    description: 'AI provider to use: "github-models" or "anthropic"'
+    required: false
+    default: "github-models"
   anthropic-api-key:
-    description: "Anthropic API key for Claude"
-    required: true
+    description: 'Anthropic API key for Claude (required when provider is "anthropic")'
+    required: false
+    default: ""
   prompt:
     description: "Optional custom instructions appended to the prompt"
     required: false
     default: ""
   model:
-    description: "Claude model to use"
+    description: "AI model to use (defaults to provider-appropriate model if not set)"
     required: false
-    default: "claude-sonnet-4-5-20250929"
+    default: ""
 outputs:
   instructions:
     description: "The generated QA instructions"

src/claude.test.ts

@@ -14,31 +14,35 @@ vi.mock("@anthropic-ai/sdk", () => {
 	};
 });
 
-import { generateQAInstructions } from "./claude.js";
-import { DEFAULT_MODEL } from "./constants.js";
+import { createAnthropicProvider } from "./claude.js";
+import { DEFAULT_ANTHROPIC_MODEL } from "./constants.js";
 
-describe("generateQAInstructions", () => {
+describe("createAnthropicProvider", () => {
 	beforeEach(() => {
 		vi.clearAllMocks();
 	});
 
-	it("sends context to Claude and returns text response", async () => {
+	it("sends prompts to Claude and returns text response", async () => {
 		mockCreate.mockResolvedValue({
 			content: [{ type: "text", text: "## QA Instructions\n\nTest this." }],
 		});
 
-		const result = await generateQAInstructions(
+		const provider = createAnthropicProvider(
 			"test-api-key",
-			DEFAULT_MODEL,
-			"PR context here",
+			DEFAULT_ANTHROPIC_MODEL,
+		);
+		const result = await provider.generateQAInstructions(
+			"system prompt",
+			"user prompt",
 		);
 
 		expect(result).toBe("## QA Instructions\n\nTest this.");
 		expect(mockCreate).toHaveBeenCalledWith(
 			expect.objectContaining({
-				model: DEFAULT_MODEL,
+				model: DEFAULT_ANTHROPIC_MODEL,
 				max_tokens: 4096,
-				messages: [{ role: "user", content: "PR context here" }],
+				system: "system prompt",
+				messages: [{ role: "user", content: "user prompt" }],
 			}),
 		);
 	});
@@ -48,8 +52,10 @@ describe("generateQAInstructions", () => {
 			content: [],
 		});
 
+		const provider = createAnthropicProvider("key", "model");
+
 		await expect(
-			generateQAInstructions("key", "model", "context"),
+			provider.generateQAInstructions("system", "user"),
 		).rejects.toThrow("No text content in Claude response");
 	});
 });

src/claude.ts

@@ -1,42 +1,30 @@
 import Anthropic from "@anthropic-ai/sdk";
+import type { AiProvider } from "./types.js";
 
-const SYSTEM_PROMPT = `You are an expert QA engineer reviewing a pull request. Your job is to generate clear, actionable QA testing instructions that a human tester can follow.
-
-Scale your response to the complexity of the changes. A small documentation fix needs just a sentence or two. A large feature needs thorough coverage. Be concise — omit sections that add no value for the specific PR.
-
-Analyze the provided PR context and produce testing instructions using whichever of these sections are relevant:
-
-- **Summary** — What the PR changes and why (1-3 sentences).
-- **Test Environment Setup** — Prerequisites or setup steps, if any beyond the standard dev environment. Omit if none.
-- **Test Scenarios** — Numbered test cases with steps and expected results. Focus on the most important paths; don't enumerate the obvious.
-- **Regression Risks** — Areas that might break as a side effect. Omit if the changes are well-isolated.
-- **Things to Watch For** — Edge cases or concerns spotted in the code. Omit if nothing stands out.
-
-Be specific and practical. Reference actual file names, function names, and UI elements from the PR when possible.`;
-
-export async function generateQAInstructions(
+export function createAnthropicProvider(
 	apiKey: string,
 	model: string,
-	promptContext: string,
-): Promise<string> {
+): AiProvider {
 	const client = new Anthropic({ apiKey });
 
-	const response = await client.messages.create({
-		model,
-		max_tokens: 4096,
-		system: SYSTEM_PROMPT,
-		messages: [
-			{
-				role: "user",
-				content: promptContext,
-			},
-		],
-	});
-
-	const textBlock = response.content.find((block) => block.type === "text");
-	if (!textBlock || textBlock.type !== "text") {
-		throw new Error("No text content in Claude response");
-	}
-
-	return textBlock.text;
+	return {
+		async generateQAInstructions(
+			systemPrompt: string,
+			userPrompt: string,
+		): Promise<string> {
+			const response = await client.messages.create({
+				model,
+				max_tokens: 4096,
+				system: systemPrompt,
+				messages: [{ role: "user", content: userPrompt }],
+			});
+
+			const textBlock = response.content.find((block) => block.type === "text");
+			if (!textBlock || textBlock.type !== "text") {
+				throw new Error("No text content in Claude response");
+			}
+
+			return textBlock.text;
+		},
+	};
 }

src/constants.ts

@@ -1,9 +1,52 @@
 export const COMMENT_MARKER = "<!-- qa-instructions-action -->";
 
-export const DEFAULT_MODEL = "claude-sonnet-4-5-20250929";
+export const VALID_PROVIDERS = ["github-models", "anthropic"] as const;
+export type Provider = (typeof VALID_PROVIDERS)[number];
 
-export const MAX_DIFF_CHARS = 80_000;
-export const MAX_CHANGED_FILES_CHARS = 60_000;
-export const MAX_FILE_CHARS = 10_000;
-export const MAX_FILE_TREE_CHARS = 20_000;
-export const MAX_TOTAL_CHARS = 180_000;
+export const DEFAULT_ANTHROPIC_MODEL = "claude-sonnet-4-5-20250929";
+export const DEFAULT_GITHUB_MODELS_MODEL = "openai/gpt-4o";
+
+export const GITHUB_MODELS_BASE_URL =
+	"https://models.github.ai/inference/chat/completions";
+
+export interface ContextLimits {
+	maxDiffChars: number;
+	maxChangedFilesChars: number;
+	maxFileChars: number;
+	maxFileTreeChars: number;
+	maxTotalChars: number;
+}
+
+export const ANTHROPIC_CONTEXT_LIMITS: ContextLimits = {
+	maxDiffChars: 80_000,
+	maxChangedFilesChars: 60_000,
+	maxFileChars: 10_000,
+	maxFileTreeChars: 20_000,
+	maxTotalChars: 180_000,
+};
+
+// GitHub Models free tier: 8k input tokens for gpt-4o (~32k chars).
+// JSON encoding inflates newlines (\n → \\n), so budget ~20k chars
+// for the user prompt after reserving room for the system prompt and
+// JSON/HTTP overhead.
+export const GITHUB_MODELS_CONTEXT_LIMITS: ContextLimits = {
+	maxDiffChars: 8_000,
+	maxChangedFilesChars: 6_000,
+	maxFileChars: 3_000,
+	maxFileTreeChars: 3_000,
+	maxTotalChars: 20_000,
+};
+
+export const SYSTEM_PROMPT = `You are an expert QA engineer reviewing a pull request. Your job is to generate clear, actionable QA testing instructions that a human tester can follow.
+
+Scale your response to the complexity of the changes. A small documentation fix needs just a sentence or two. A large feature needs thorough coverage. Be concise — omit sections that add no value for the specific PR.
+
+Analyze the provided PR context and produce testing instructions using whichever of these sections are relevant:
+
+- **Summary** — What the PR changes and why (1-3 sentences).
+- **Test Environment Setup** — Prerequisites or setup steps, if any beyond the standard dev environment. Omit if none.
+- **Test Scenarios** — Numbered test cases with steps and expected results. Focus on the most important paths; don't enumerate the obvious.
+- **Regression Risks** — Areas that might break as a side effect. Omit if the changes are well-isolated.
+- **Things to Watch For** — Edge cases or concerns spotted in the code. Omit if nothing stands out.
+
+Be specific and practical. Reference actual file names, function names, and UI elements from the PR when possible.`;