Revert "Remove Anthropic OAuth support"

This reverts commit f5e6bcac1b.

packages/coding-agent/README.md

@@ -158,7 +158,7 @@ Add API keys to `~/.pi/agent/auth.json`:
 
 | Provider | Auth Key | Environment Variable |
 |----------|--------------|---------------------|
-| Anthropic | `anthropic` | `ANTHROPIC_API_KEY`, `ANTHROPIC_OAUTH_TOKEN` |
+| Anthropic | `anthropic` | `ANTHROPIC_API_KEY` |
 | OpenAI | `openai` | `OPENAI_API_KEY` |
 | Google | `google` | `GEMINI_API_KEY` |
 | Mistral | `mistral` | `MISTRAL_API_KEY` |
@@ -176,6 +176,7 @@ Use `/login` to authenticate with subscription-based or free-tier providers:
 
 | Provider | Models | Cost |
 |----------|--------|------|
+| Anthropic (Claude Pro/Max) | Claude models via your subscription | Subscription |
 | GitHub Copilot | GPT-4o, Claude, Gemini via Copilot subscription | Subscription |
 | Google Gemini CLI | Gemini 2.0/2.5 models | Free (Google account) |
 | Google Antigravity | Gemini 3, Claude, GPT-OSS | Free (Google account) |

packages/coding-agent/examples/extensions/snake.ts

@@ -156,23 +156,9 @@ class SnakeComponent {
 				this.onClose();
 				return;
 			}
-			// Any other key resumes (including P)
+			// Any other key resumes
 			this.paused = false;
 			this.startGame();
-			this.version++;
-			this.tui.requestRender();
-			return;
-		}
-
-		// P to pause without closing
-		if (data === "p" || data === "P") {
-			this.paused = true;
-			if (this.interval) {
-				clearInterval(this.interval);
-				this.interval = null;
-			}
-			this.version++;
-			this.tui.requestRender();
 			return;
 		}
 
@@ -289,7 +275,7 @@ class SnakeComponent {
 		} else if (this.state.gameOver) {
 			footer = `${red(bold("GAME OVER!"))} Press ${bold("R")} to restart, ${bold("Q")} to quit`;
 		} else {
-			footer = `↑↓←→ or WASD to move, ${bold("P")} pause, ${bold("ESC")} save+quit, ${bold("Q")} quit`;
+			footer = `↑↓←→ or WASD to move, ${bold("ESC")} pause, ${bold("Q")} quit`;
 		}
 		lines.push(this.padLine(boxLine(footer), width));
 

packages/coding-agent/src/core/auth-storage.ts

@@ -9,6 +9,7 @@
 import {
 	getEnvApiKey,
 	getOAuthApiKey,
+	loginAnthropic,
 	loginAntigravity,
 	loginGeminiCli,
 	loginGitHubCopilot,
@@ -169,6 +170,12 @@ export class AuthStorage {
 		let credentials: OAuthCredentials;
 
 		switch (provider) {
+			case "anthropic":
+				credentials = await loginAnthropic(
+					(url) => callbacks.onAuth({ url }),
+					() => callbacks.onPrompt({ message: "Paste the authorization code:" }),
+				);
+				break;
 			case "github-copilot":
 				credentials = await loginGitHubCopilot({
 					onAuth: (url, instructions) => callbacks.onAuth({ url, instructions }),

packages/coding-agent/src/core/system-prompt.ts

@@ -303,6 +303,5 @@ Documentation:
 	prompt += `\nCurrent date and time: ${dateTime}`;
 	prompt += `\nCurrent working directory: ${resolvedCwd}`;
 
-	prompt = "You are a helpful assistant. Be concise.";
 	return prompt;
 }