feat: add provider-scoped environment overrides (#5807)

packages/ai/src/utils/provider-env.ts

@@ -0,0 +1,52 @@
+import type { ProviderEnv } from "../types.ts";
+
+let procEnvCache: Map<string, string> | null = null;
+
+/**
+ * Fallback for https://github.com/oven-sh/bun/issues/27802.
+ * Bun compiled binaries can expose an empty process.env inside Linux sandboxes
+ * even though /proc/self/environ contains the environment.
+ *
+ * This intentionally duplicates restoreSandboxEnv() in
+ * packages/coding-agent/src/bun/restore-sandbox-env.ts. The ai package can be
+ * used directly, without going through that entrypoint, so provider env lookup
+ * must not depend on process.env having been patched.
+ */
+function getBunSandboxEnvValue(name: string): string | undefined {
+	if (typeof process === "undefined" || !process.versions?.bun || Object.keys(process.env).length > 0) {
+		return undefined;
+	}
+
+	if (procEnvCache === null) {
+		procEnvCache = new Map();
+		try {
+			const { readFileSync } = require("node:fs") as {
+				readFileSync(path: string, encoding: BufferEncoding): string;
+			};
+			const data = readFileSync("/proc/self/environ", "utf-8");
+			for (const entry of data.split("\0")) {
+				const idx = entry.indexOf("=");
+				if (idx > 0) {
+					procEnvCache.set(entry.slice(0, idx), entry.slice(idx + 1));
+				}
+			}
+		} catch {
+			// /proc/self/environ may not exist or may not be readable.
+		}
+	}
+
+	return procEnvCache.get(name);
+}
+
+/**
+ * Resolve a provider env value from scoped overrides, normal process.env, then
+ * the duplicated Bun sandbox fallback for direct pi-ai consumers.
+ */
+export function getProviderEnvValue(name: string, env?: ProviderEnv): string | undefined {
+	return (
+		env?.[name] ||
+		(typeof process !== "undefined" ? process.env[name] : undefined) ||
+		getBunSandboxEnvValue(name) ||
+		undefined
+	);
+}