refactor: simplify proxy env watching and document the approach

Derive the watched proxy settings from a single SSH_PROXY_SETTINGS source,
collapse the redundant useLocalServer/useExecServer test matrix, and document
why the proxy variables are propagated via process.env.

Author: EhabY

src/remote/environment.ts

@@ -1,10 +1,13 @@
 /**
- * Helpers for local process environment inherited by Remote-SSH children.
+ * Sets HTTP_PROXY/HTTPS_PROXY/NO_PROXY on this extension host's process.env so
+ * the spawned `coder ssh` ProxyCommand inherits them (the coder CLI reads them
+ * like any Go HTTP client and has no proxy flag). We mutate process.env rather
+ * than baking them into the SSH config so no credentialed proxy URL is written
+ * to disk and multiple windows onto the same workspace stay independent.
  *
- * This is best-effort: it affects processes spawned after these values are
- * applied. Modes such as `remote.SSH.useLocalServer` can reuse existing local
- * SSH processes, and `remote.SSH.useExecServer` changes the bootstrap path, so
- * already-running processes may need a reload/reconnect to inherit changes.
+ * Best-effort: only processes spawned after it runs inherit the change. Notably
+ * MS VS Code with `remote.SSH.useLocalServer=false` spawns ssh off a path that
+ * does not inherit, so propagation there needs `useLocalServer=true`.
  */
 
 import { getProxyForUrl } from "../api/proxy";
@@ -15,6 +18,19 @@ export type SshProxyEnvironment = Partial<
 	Record<"HTTP_PROXY" | "HTTPS_PROXY" | "NO_PROXY", string>
 >;
 
+/**
+ * The settings {@link getSshProxyEnvironment} reads, paired with display titles.
+ * Watch these to prompt for a reload when the SSH proxy environment changes.
+ */
+export const SSH_PROXY_SETTINGS: ReadonlyArray<{
+	setting: string;
+	title: string;
+}> = [
+	{ setting: "http.proxy", title: "HTTP Proxy" },
+	{ setting: "http.noProxy", title: "HTTP No Proxy" },
+	{ setting: "coder.proxyBypass", title: "Proxy Bypass" },
+];
+
 type Environment = Record<string, string | undefined>;
 type PreviousValue = [key: string, existed: boolean, value: string | undefined];
 

src/remote/remote.ts

@@ -61,7 +61,7 @@ import {
 import { vscodeProposed } from "../vscodeProposed";
 import { WorkspaceMonitor } from "../workspace/workspaceMonitor";
 
-import { applySshProxyEnvironment } from "./environment";
+import { applySshProxyEnvironment, SSH_PROXY_SETTINGS } from "./environment";
 import {
 	SshConfig,
 	type SshValues,
@@ -458,24 +458,11 @@ export class Remote {
 					title: "SSH Flags",
 					getValue: () => getSshFlags(vscode.workspace.getConfiguration()),
 				},
-				{
-					setting: "http.proxy",
-					title: "HTTP Proxy",
-					getValue: () =>
-						vscode.workspace.getConfiguration().get("http.proxy") ?? "",
-				},
-				{
-					setting: "http.noProxy",
-					title: "HTTP No Proxy",
-					getValue: () =>
-						vscode.workspace.getConfiguration().get("http.noProxy") ?? [],
-				},
-				{
-					setting: "coder.proxyBypass",
-					title: "Proxy Bypass",
-					getValue: () =>
-						vscode.workspace.getConfiguration().get("coder.proxyBypass") ?? "",
-				},
+				...SSH_PROXY_SETTINGS.map(({ setting, title }) => ({
+					setting,
+					title,
+					getValue: () => vscode.workspace.getConfiguration().get(setting),
+				})),
 			];
 			if (featureSet.proxyLogDirectory) {
 				settingsToWatch.push({

test/unit/remote/environment.test.ts

@@ -127,55 +127,20 @@ describe("applySshProxyEnvironment", () => {
 		});
 	});
 
-	interface RemoteSshModeCase {
-		name: string;
-		useExecServer: boolean;
-		useLocalServer: boolean;
-	}
-
-	it.each<RemoteSshModeCase>([
-		{
-			name: "local server and exec server",
-			useLocalServer: true,
-			useExecServer: true,
-		},
-		{
-			name: "local server without exec server",
-			useLocalServer: true,
-			useExecServer: false,
-		},
-		{
-			name: "terminal server and exec server",
-			useLocalServer: false,
-			useExecServer: true,
-		},
-		{
-			name: "terminal server without exec server",
-			useLocalServer: false,
-			useExecServer: false,
-		},
-	])(
-		"propagates proxy variables to new child processes with $name",
-		({ useExecServer, useLocalServer }) => {
-			const cfg = new MockConfigurationProvider();
-			cfg.set("http.proxy", proxy);
-			cfg.set("remote.SSH.useExecServer", useExecServer);
-			cfg.set("remote.SSH.useLocalServer", useLocalServer);
-			const applied = applySshProxyEnvironment(
-				"https://coder.example.com",
-				cfg,
-			);
-
-			try {
-				expect(getProxyEnvFromChild()).toEqual({
-					http: proxy,
-					https: proxy,
-				});
-			} finally {
-				applied.dispose();
-			}
-		},
-	);
+	it("propagates proxy variables to newly spawned child processes", () => {
+		const cfg = new MockConfigurationProvider();
+		cfg.set("http.proxy", proxy);
+		const applied = applySshProxyEnvironment("https://coder.example.com", cfg);
+
+		try {
+			expect(getProxyEnvFromChild()).toEqual({
+				http: proxy,
+				https: proxy,
+			});
+		} finally {
+			applied.dispose();
+		}
+	});
 });
 
 interface ChildProxyEnvironment {