diff --git a/src/agents/tools/web-guarded-fetch.test.ts b/src/agents/tools/web-guarded-fetch.test.ts
index 87b0ba9a5ae..005a94ad3da 100644
--- a/src/agents/tools/web-guarded-fetch.test.ts
+++ b/src/agents/tools/web-guarded-fetch.test.ts
@@ -1,10 +1,25 @@
 import { afterEach, describe, expect, it, vi } from "vitest";
-import { fetchWithSsrFGuard } from "../../infra/net/fetch-guard.js";
+import { fetchWithSsrFGuard, GUARDED_FETCH_MODE } from "../../infra/net/fetch-guard.js";
 import { withStrictWebToolsEndpoint, withTrustedWebToolsEndpoint } from "./web-guarded-fetch.js";
 
-vi.mock("../../infra/net/fetch-guard.js", () => ({
-  fetchWithSsrFGuard: vi.fn(),
-}));
+vi.mock("../../infra/net/fetch-guard.js", () => {
+  const GUARDED_FETCH_MODE = {
+    STRICT: "strict",
+    TRUSTED_ENV_PROXY: "trusted_env_proxy",
+  } as const;
+  return {
+    GUARDED_FETCH_MODE,
+    fetchWithSsrFGuard: vi.fn(),
+    withStrictGuardedFetchMode: (params: Record<string, unknown>) => ({
+      ...params,
+      mode: GUARDED_FETCH_MODE.STRICT,
+    }),
+    withTrustedEnvProxyGuardedFetchMode: (params: Record<string, unknown>) => ({
+      ...params,
+      mode: GUARDED_FETCH_MODE.TRUSTED_ENV_PROXY,
+    }),
+  };
+});
 
 describe("web-guarded-fetch", () => {
   afterEach(() => {
@@ -27,8 +42,7 @@ describe("web-guarded-fetch", () => {
           dangerouslyAllowPrivateNetwork: true,
           allowRfc2544BenchmarkRange: true,
         }),
-        proxy: "env",
-        dangerouslyAllowEnvProxyWithoutPinnedDns: true,
+        mode: GUARDED_FETCH_MODE.TRUSTED_ENV_PROXY,
       }),
     );
   });
@@ -49,7 +63,6 @@ describe("web-guarded-fetch", () => {
     );
     const call = vi.mocked(fetchWithSsrFGuard).mock.calls[0]?.[0];
     expect(call?.policy).toBeUndefined();
-    expect(call?.proxy).toBeUndefined();
-    expect(call?.dangerouslyAllowEnvProxyWithoutPinnedDns).toBeUndefined();
+    expect(call?.mode).toBe(GUARDED_FETCH_MODE.STRICT);
   });
 });
diff --git a/src/agents/tools/web-guarded-fetch.ts b/src/agents/tools/web-guarded-fetch.ts
index c6c644fb4e2..aa4e8274cf9 100644
--- a/src/agents/tools/web-guarded-fetch.ts
+++ b/src/agents/tools/web-guarded-fetch.ts
@@ -2,6 +2,8 @@ import {
   fetchWithSsrFGuard,
   type GuardedFetchOptions,
   type GuardedFetchResult,
+  withStrictGuardedFetchMode,
+  withTrustedEnvProxyGuardedFetchMode,
 } from "../../infra/net/fetch-guard.js";
 import type { SsrFPolicy } from "../../infra/net/ssrf.js";
 
@@ -12,7 +14,7 @@ const WEB_TOOLS_TRUSTED_NETWORK_SSRF_POLICY: SsrFPolicy = {
 
 type WebToolGuardedFetchOptions = Omit<
   GuardedFetchOptions,
-  "proxy" | "dangerouslyAllowEnvProxyWithoutPinnedDns"
+  "mode" | "proxy" | "dangerouslyAllowEnvProxyWithoutPinnedDns"
 > & {
   timeoutSeconds?: number;
   useEnvProxy?: boolean;
@@ -36,16 +38,15 @@ export async function fetchWithWebToolsNetworkGuard(
   params: WebToolGuardedFetchOptions,
 ): Promise<GuardedFetchResult> {
   const { timeoutSeconds, useEnvProxy, ...rest } = params;
-  return fetchWithSsrFGuard({
+  const resolved = {
     ...rest,
     timeoutMs: resolveTimeoutMs({ timeoutMs: rest.timeoutMs, timeoutSeconds }),
-    ...(useEnvProxy
-      ? {
-          proxy: "env",
-          dangerouslyAllowEnvProxyWithoutPinnedDns: true,
-        }
-      : {}),
-  });
+  };
+  return fetchWithSsrFGuard(
+    useEnvProxy
+      ? withTrustedEnvProxyGuardedFetchMode(resolved)
+      : withStrictGuardedFetchMode(resolved),
+  );
 }
 
 async function withWebToolsNetworkGuard<T>(
diff --git a/src/browser/cdp-proxy-bypass.ts b/src/browser/cdp-proxy-bypass.ts
index 7f579370de2..8db5276fc51 100644
--- a/src/browser/cdp-proxy-bypass.ts
+++ b/src/browser/cdp-proxy-bypass.ts
@@ -10,6 +10,7 @@
 import http from "node:http";
 import https from "node:https";
 import { isLoopbackHost } from "../gateway/net.js";
+import { hasProxyEnvConfigured } from "../infra/net/proxy-env.js";
 
 /** HTTP agent that never uses a proxy — for localhost CDP connections. */
 const directHttpAgent = new http.Agent();
@@ -39,15 +40,7 @@ export function getDirectAgentForCdp(url: string): http.Agent | https.Agent | un
  * interfere with loopback connections.
  */
 export function hasProxyEnv(): boolean {
-  const env = process.env;
-  return Boolean(
-    env.HTTP_PROXY ||
-    env.http_proxy ||
-    env.HTTPS_PROXY ||
-    env.https_proxy ||
-    env.ALL_PROXY ||
-    env.all_proxy,
-  );
+  return hasProxyEnvConfigured();
 }
 
 const LOOPBACK_ENTRIES = "localhost,127.0.0.1,[::1]";
diff --git a/src/browser/navigation-guard.ts b/src/browser/navigation-guard.ts
index 73d1b41ba3d..496dee19469 100644
--- a/src/browser/navigation-guard.ts
+++ b/src/browser/navigation-guard.ts
@@ -1,4 +1,6 @@
+import { hasProxyEnvConfigured } from "../infra/net/proxy-env.js";
 import {
+  isPrivateNetworkAllowedByPolicy,
   resolvePinnedHostnameWithPolicy,
   type LookupFn,
   type SsrFPolicy,
@@ -6,28 +8,6 @@ import {
 
 const NETWORK_NAVIGATION_PROTOCOLS = new Set(["http:", "https:"]);
 const SAFE_NON_NETWORK_URLS = new Set(["about:blank"]);
-const ENV_PROXY_KEYS = [
-  "HTTP_PROXY",
-  "HTTPS_PROXY",
-  "ALL_PROXY",
-  "http_proxy",
-  "https_proxy",
-  "all_proxy",
-] as const;
-
-function hasEnvProxyConfigured(): boolean {
-  for (const key of ENV_PROXY_KEYS) {
-    const value = process.env[key];
-    if (typeof value === "string" && value.trim().length > 0) {
-      return true;
-    }
-  }
-  return false;
-}
-
-function allowsPrivateNetworkNavigation(policy?: SsrFPolicy): boolean {
-  return policy?.dangerouslyAllowPrivateNetwork === true || policy?.allowPrivateNetwork === true;
-}
 
 function isAllowedNonNetworkNavigationUrl(parsed: URL): boolean {
   // Keep non-network navigation explicit; about:blank is the only allowed bootstrap URL.
@@ -82,7 +62,7 @@ export async function assertBrowserNavigationAllowed(
   // can bypass strict destination-binding intent from pre-navigation DNS checks.
   // In strict mode, fail closed unless private-network navigation is explicitly
   // enabled by policy.
-  if (hasEnvProxyConfigured() && !allowsPrivateNetworkNavigation(opts.ssrfPolicy)) {
+  if (hasProxyEnvConfigured() && !isPrivateNetworkAllowedByPolicy(opts.ssrfPolicy)) {
     throw new InvalidBrowserNavigationUrlError(
       "Navigation blocked: strict browser SSRF policy cannot be enforced while env proxy variables are set",
     );
diff --git a/src/infra/net/fetch-guard.ssrf.test.ts b/src/infra/net/fetch-guard.ssrf.test.ts
index 780f2d94d99..e686f46e075 100644
--- a/src/infra/net/fetch-guard.ssrf.test.ts
+++ b/src/infra/net/fetch-guard.ssrf.test.ts
@@ -1,6 +1,6 @@
 import { EnvHttpProxyAgent } from "undici";
 import { afterEach, describe, expect, it, vi } from "vitest";
-import { fetchWithSsrFGuard } from "./fetch-guard.js";
+import { fetchWithSsrFGuard, GUARDED_FETCH_MODE } from "./fetch-guard.js";
 
 function redirectResponse(location: string): Response {
   return new Response(null, {
@@ -180,7 +180,7 @@ describe("fetchWithSsrFGuard hardening", () => {
       url: "https://public.example/resource",
       fetchImpl,
       lookupFn,
-      proxy: "env",
+      mode: GUARDED_FETCH_MODE.STRICT,
     });
 
     expect(fetchImpl).toHaveBeenCalledTimes(1);
@@ -202,8 +202,7 @@ describe("fetchWithSsrFGuard hardening", () => {
       url: "https://public.example/resource",
       fetchImpl,
       lookupFn,
-      proxy: "env",
-      dangerouslyAllowEnvProxyWithoutPinnedDns: true,
+      mode: GUARDED_FETCH_MODE.TRUSTED_ENV_PROXY,
     });
 
     expect(fetchImpl).toHaveBeenCalledTimes(1);
diff --git a/src/infra/net/fetch-guard.ts b/src/infra/net/fetch-guard.ts
index 06847f841c1..ded0c5fae21 100644
--- a/src/infra/net/fetch-guard.ts
+++ b/src/infra/net/fetch-guard.ts
@@ -1,6 +1,7 @@
 import { EnvHttpProxyAgent, type Dispatcher } from "undici";
 import { logWarn } from "../../logger.js";
 import { bindAbortRelay } from "../../utils/fetch-timeout.js";
+import { hasProxyEnvConfigured } from "./proxy-env.js";
 import {
   closeDispatcher,
   createPinnedDispatcher,
@@ -12,6 +13,13 @@ import {
 
 type FetchLike = (input: RequestInfo | URL, init?: RequestInit) => Promise<Response>;
 
+export const GUARDED_FETCH_MODE = {
+  STRICT: "strict",
+  TRUSTED_ENV_PROXY: "trusted_env_proxy",
+} as const;
+
+export type GuardedFetchMode = (typeof GUARDED_FETCH_MODE)[keyof typeof GUARDED_FETCH_MODE];
+
 export type GuardedFetchOptions = {
   url: string;
   fetchImpl?: FetchLike;
@@ -21,11 +29,12 @@ export type GuardedFetchOptions = {
   signal?: AbortSignal;
   policy?: SsrFPolicy;
   lookupFn?: LookupFn;
+  mode?: GuardedFetchMode;
   pinDns?: boolean;
+  /** @deprecated use `mode: "trusted_env_proxy"` for trusted/operator-controlled URLs. */
   proxy?: "env";
   /**
-   * Env proxies can break destination binding between SSRF pre-check and connect-time target.
-   * Keep this off for untrusted URLs; enable only for trusted/operator-controlled endpoints.
+   * @deprecated use `mode: "trusted_env_proxy"` instead.
    */
   dangerouslyAllowEnvProxyWithoutPinnedDns?: boolean;
   auditContext?: string;
@@ -37,15 +46,12 @@ export type GuardedFetchResult = {
   release: () => Promise<void>;
 };
 
+type GuardedFetchPresetOptions = Omit<
+  GuardedFetchOptions,
+  "mode" | "proxy" | "dangerouslyAllowEnvProxyWithoutPinnedDns"
+>;
+
 const DEFAULT_MAX_REDIRECTS = 3;
-const ENV_PROXY_KEYS = [
-  "HTTP_PROXY",
-  "HTTPS_PROXY",
-  "ALL_PROXY",
-  "http_proxy",
-  "https_proxy",
-  "all_proxy",
-] as const;
 const CROSS_ORIGIN_REDIRECT_SENSITIVE_HEADERS = [
   "authorization",
   "proxy-authorization",
@@ -53,14 +59,24 @@ const CROSS_ORIGIN_REDIRECT_SENSITIVE_HEADERS = [
   "cookie2",
 ];
 
-function hasEnvProxyConfigured(): boolean {
-  for (const key of ENV_PROXY_KEYS) {
-    const value = process.env[key];
-    if (typeof value === "string" && value.trim()) {
-      return true;
-    }
+export function withStrictGuardedFetchMode(params: GuardedFetchPresetOptions): GuardedFetchOptions {
+  return { ...params, mode: GUARDED_FETCH_MODE.STRICT };
+}
+
+export function withTrustedEnvProxyGuardedFetchMode(
+  params: GuardedFetchPresetOptions,
+): GuardedFetchOptions {
+  return { ...params, mode: GUARDED_FETCH_MODE.TRUSTED_ENV_PROXY };
+}
+
+function resolveGuardedFetchMode(params: GuardedFetchOptions): GuardedFetchMode {
+  if (params.mode) {
+    return params.mode;
   }
-  return false;
+  if (params.proxy === "env" && params.dangerouslyAllowEnvProxyWithoutPinnedDns === true) {
+    return GUARDED_FETCH_MODE.TRUSTED_ENV_PROXY;
+  }
+  return GUARDED_FETCH_MODE.STRICT;
 }
 
 function isRedirectStatus(status: number): boolean {
@@ -122,6 +138,7 @@ export async function fetchWithSsrFGuard(params: GuardedFetchOptions): Promise<G
     typeof params.maxRedirects === "number" && Number.isFinite(params.maxRedirects)
       ? Math.max(0, Math.floor(params.maxRedirects))
       : DEFAULT_MAX_REDIRECTS;
+  const mode = resolveGuardedFetchMode(params);
 
   const { signal, cleanup } = buildAbortSignal({
     timeoutMs: params.timeoutMs,
@@ -162,8 +179,9 @@ export async function fetchWithSsrFGuard(params: GuardedFetchOptions): Promise<G
         lookupFn: params.lookupFn,
         policy: params.policy,
       });
-      const hasEnvProxy = params.proxy === "env" && hasEnvProxyConfigured();
-      if (hasEnvProxy && params.dangerouslyAllowEnvProxyWithoutPinnedDns === true) {
+      const canUseTrustedEnvProxy =
+        mode === GUARDED_FETCH_MODE.TRUSTED_ENV_PROXY && hasProxyEnvConfigured();
+      if (canUseTrustedEnvProxy) {
         dispatcher = new EnvHttpProxyAgent();
       } else if (params.pinDns !== false) {
         dispatcher = createPinnedDispatcher(pinned);
diff --git a/src/infra/net/proxy-env.ts b/src/infra/net/proxy-env.ts
new file mode 100644
index 00000000000..01401074678
--- /dev/null
+++ b/src/infra/net/proxy-env.ts
@@ -0,0 +1,18 @@
+export const PROXY_ENV_KEYS = [
+  "HTTP_PROXY",
+  "HTTPS_PROXY",
+  "ALL_PROXY",
+  "http_proxy",
+  "https_proxy",
+  "all_proxy",
+] as const;
+
+export function hasProxyEnvConfigured(env: NodeJS.ProcessEnv = process.env): boolean {
+  for (const key of PROXY_ENV_KEYS) {
+    const value = env[key];
+    if (typeof value === "string" && value.trim().length > 0) {
+      return true;
+    }
+  }
+  return false;
+}
diff --git a/src/infra/net/ssrf.ts b/src/infra/net/ssrf.ts
index 7798e5990a4..45fba10fd30 100644
--- a/src/infra/net/ssrf.ts
+++ b/src/infra/net/ssrf.ts
@@ -63,7 +63,7 @@ function normalizeHostnameAllowlist(values?: string[]): string[] {
   );
 }
 
-function resolveAllowPrivateNetwork(policy?: SsrFPolicy): boolean {
+export function isPrivateNetworkAllowedByPolicy(policy?: SsrFPolicy): boolean {
   return policy?.dangerouslyAllowPrivateNetwork === true || policy?.allowPrivateNetwork === true;
 }
 
@@ -282,7 +282,7 @@ export async function resolvePinnedHostnameWithPolicy(
     throw new Error("Invalid hostname");
   }
 
-  const allowPrivateNetwork = resolveAllowPrivateNetwork(params.policy);
+  const allowPrivateNetwork = isPrivateNetworkAllowedByPolicy(params.policy);
   const allowedHostnames = normalizeHostnameSet(params.policy?.allowedHostnames);
   const hostnameAllowlist = normalizeHostnameAllowlist(params.policy?.hostnameAllowlist);
   const isExplicitAllowed = allowedHostnames.has(normalized);
diff --git a/src/media/fetch.ts b/src/media/fetch.ts
index 2991cda5bea..3f2372c0abf 100644
--- a/src/media/fetch.ts
+++ b/src/media/fetch.ts
@@ -1,5 +1,5 @@
 import path from "node:path";
-import { fetchWithSsrFGuard } from "../infra/net/fetch-guard.js";
+import { fetchWithSsrFGuard, withStrictGuardedFetchMode } from "../infra/net/fetch-guard.js";
 import type { LookupFn, SsrFPolicy } from "../infra/net/ssrf.js";
 import { detectMime, extensionForMime } from "./mime.js";
 import { readResponseWithLimit } from "./read-response-with-limit.js";
@@ -95,14 +95,16 @@ export async function fetchRemoteMedia(options: FetchMediaOptions): Promise<Fetc
   let finalUrl = url;
   let release: (() => Promise<void>) | null = null;
   try {
-    const result = await fetchWithSsrFGuard({
-      url,
-      fetchImpl,
-      init: requestInit,
-      maxRedirects,
-      policy: ssrfPolicy,
-      lookupFn,
-    });
+    const result = await fetchWithSsrFGuard(
+      withStrictGuardedFetchMode({
+        url,
+        fetchImpl,
+        init: requestInit,
+        maxRedirects,
+        policy: ssrfPolicy,
+        lookupFn,
+      }),
+    );
     res = result.response;
     finalUrl = result.finalUrl;
     release = result.release;
diff --git a/src/slack/send.ts b/src/slack/send.ts
index 8495ef2ed24..fcfe230f7dc 100644
--- a/src/slack/send.ts
+++ b/src/slack/send.ts
@@ -8,7 +8,10 @@ import { isSilentReplyText } from "../auto-reply/tokens.js";
 import { loadConfig } from "../config/config.js";
 import { resolveMarkdownTableMode } from "../config/markdown-tables.js";
 import { logVerbose } from "../globals.js";
-import { fetchWithSsrFGuard } from "../infra/net/fetch-guard.js";
+import {
+  fetchWithSsrFGuard,
+  withTrustedEnvProxyGuardedFetchMode,
+} from "../infra/net/fetch-guard.js";
 import { loadWebMedia } from "../web/media.js";
 import type { SlackTokenSource } from "./accounts.js";
 import { resolveSlackAccount } from "./accounts.js";
@@ -211,18 +214,18 @@ async function uploadSlackFile(params: {
 
   // Upload the file content to the presigned URL
   const uploadBody = new Uint8Array(buffer) as BodyInit;
-  const { response: uploadResp, release } = await fetchWithSsrFGuard({
-    url: uploadUrlResp.upload_url,
-    init: {
-      method: "POST",
-      ...(contentType ? { headers: { "Content-Type": contentType } } : {}),
-      body: uploadBody,
-    },
-    policy: SLACK_UPLOAD_SSRF_POLICY,
-    proxy: "env",
-    dangerouslyAllowEnvProxyWithoutPinnedDns: true,
-    auditContext: "slack-upload-file",
-  });
+  const { response: uploadResp, release } = await fetchWithSsrFGuard(
+    withTrustedEnvProxyGuardedFetchMode({
+      url: uploadUrlResp.upload_url,
+      init: {
+        method: "POST",
+        ...(contentType ? { headers: { "Content-Type": contentType } } : {}),
+        body: uploadBody,
+      },
+      policy: SLACK_UPLOAD_SSRF_POLICY,
+      auditContext: "slack-upload-file",
+    }),
+  );
   try {
     if (!uploadResp.ok) {
       throw new Error(`Failed to upload file: HTTP ${uploadResp.status}`);
diff --git a/src/slack/send.upload.test.ts b/src/slack/send.upload.test.ts
index a156d1b84bf..7ff05183b6c 100644
--- a/src/slack/send.upload.test.ts
+++ b/src/slack/send.upload.test.ts
@@ -16,6 +16,10 @@ const fetchWithSsrFGuard = vi.fn(
 vi.mock("../infra/net/fetch-guard.js", () => ({
   fetchWithSsrFGuard: (...args: unknown[]) =>
     fetchWithSsrFGuard(...(args as [params: { url: string; init?: RequestInit }])),
+  withTrustedEnvProxyGuardedFetchMode: (params: Record<string, unknown>) => ({
+    ...params,
+    mode: "trusted_env_proxy",
+  }),
 }));
 
 vi.mock("../web/media.js", () => ({
@@ -167,8 +171,7 @@ describe("sendMessageSlack file upload with user IDs", () => {
     expect(fetchWithSsrFGuard).toHaveBeenCalledWith(
       expect.objectContaining({
         url: "https://uploads.slack.test/upload",
-        proxy: "env",
-        dangerouslyAllowEnvProxyWithoutPinnedDns: true,
+        mode: "trusted_env_proxy",
         auditContext: "slack-upload-file",
       }),
     );
diff --git a/src/telegram/fetch.ts b/src/telegram/fetch.ts
index 91a5ef9931d..f1e50021e92 100644
--- a/src/telegram/fetch.ts
+++ b/src/telegram/fetch.ts
@@ -3,6 +3,7 @@ import * as net from "node:net";
 import { EnvHttpProxyAgent, getGlobalDispatcher, setGlobalDispatcher } from "undici";
 import type { TelegramNetworkConfig } from "../config/types.telegram.js";
 import { resolveFetch } from "../infra/fetch.js";
+import { hasProxyEnvConfigured } from "../infra/net/proxy-env.js";
 import { createSubsystemLogger } from "../logging/subsystem.js";
 import {
   resolveTelegramAutoSelectFamilyDecision,
@@ -13,25 +14,6 @@ let appliedAutoSelectFamily: boolean | null = null;
 let appliedDnsResultOrder: string | null = null;
 let appliedGlobalDispatcherAutoSelectFamily: boolean | null = null;
 const log = createSubsystemLogger("telegram/network");
-const PROXY_ENV_KEYS = [
-  "HTTPS_PROXY",
-  "HTTP_PROXY",
-  "ALL_PROXY",
-  "https_proxy",
-  "http_proxy",
-  "all_proxy",
-] as const;
-
-function hasProxyEnvConfigured(): boolean {
-  for (const key of PROXY_ENV_KEYS) {
-    const value = process.env[key];
-    if (typeof value === "string" && value.trim().length > 0) {
-      return true;
-    }
-  }
-  return false;
-}
-
 function isProxyLikeDispatcher(dispatcher: unknown): boolean {
   const ctorName = (dispatcher as { constructor?: { name?: string } })?.constructor?.name;
   return typeof ctorName === "string" && ctorName.includes("ProxyAgent");