feat(anthropic): support longcat as Bearer-auth Anthropic-compatible provider

LongCat (Meituan) ships an Anthropic-compatible endpoint at
https://api.longcat.chat/anthropic that authenticates via
`Authorization: Bearer $KEY` instead of Anthropic's native `x-api-key`
header. Without this change, pi sends x-api-key and LongCat replies
with 401 invalid_api_key / missing_api_key.

Same topology as the existing alibaba-coding-plan / minimax /
minimax-cn entries (#3783).

- Add "longcat" to usesAnthropicBearerAuth() so createClient routes
  the key through authToken.
- Add "longcat": "LONGCAT_API_KEY" to env-api-keys.ts envMap so
  getEnvApiKey() can resolve it when options.apiKey is absent.
- Add "longcat" to KnownProvider so the === literal check type-checks.
- Extend anthropic-auth.test.ts to assert usesAnthropicBearerAuth
  returns true for longcat.

packages/pi-ai/src/env-api-keys.ts

@@ -141,6 +141,7 @@ export function getEnvApiKey(provider: any): string | undefined {
 		ollama: "OLLAMA_API_KEY",
 		"ollama-cloud": "OLLAMA_API_KEY",
 		"custom-openai": "CUSTOM_OPENAI_API_KEY",
+		longcat: "LONGCAT_API_KEY",
 	};
 
 	const envVar = envMap[provider];

packages/pi-ai/src/providers/anthropic-auth.test.ts

@@ -12,6 +12,7 @@ test("usesAnthropicBearerAuth covers Bearer-only Anthropic-compatible providers
 	assert.equal(usesAnthropicBearerAuth("alibaba-coding-plan"), true);
 	assert.equal(usesAnthropicBearerAuth("minimax"), true);
 	assert.equal(usesAnthropicBearerAuth("minimax-cn"), true);
+	assert.equal(usesAnthropicBearerAuth("longcat"), true);
 	assert.equal(usesAnthropicBearerAuth("anthropic"), false);
 });
 

packages/pi-ai/src/providers/anthropic.ts

@@ -45,7 +45,12 @@ function mergeHeaders(...headerSources: (Record<string, string> | undefined)[]):
 }
 
 export function usesAnthropicBearerAuth(provider: Model<"anthropic-messages">["provider"]): boolean {
-	return provider === "alibaba-coding-plan" || provider === "minimax" || provider === "minimax-cn";
+	return (
+		provider === "alibaba-coding-plan" ||
+		provider === "minimax" ||
+		provider === "minimax-cn" ||
+		provider === "longcat"
+	);
 }
 
 async function createClient(

packages/pi-ai/src/types.ts

@@ -46,7 +46,8 @@ export type KnownProvider =
 	| "alibaba-coding-plan"
 	| "alibaba-dashscope"
 	| "ollama"
-	| "ollama-cloud";
+	| "ollama-cloud"
+	| "longcat";
 export type Provider = KnownProvider | string;
 
 export type ThinkingLevel = "minimal" | "low" | "medium" | "high" | "xhigh";