refactor(host): make every remaining consumer use HostResolution

e2e-harness/__tests__/e2e-flow-snapshot.test.ts

@@ -17,6 +17,7 @@ import { WizardStore } from '@ui/tui/store';
 import { InkUI } from '@ui/tui/ink-ui';
 import { setUI } from '@ui/index';
 import { buildSession, RunPhase } from '@lib/wizard-session';
+import { HostResolution } from '@lib/host-resolution';
 import { Integration } from '@lib/constants';
 import { FRAMEWORK_REGISTRY } from '@lib/registry';
 import { WizardReadiness } from '@lib/health-checks/readiness';
@@ -66,7 +67,7 @@ function traceFlow(
       store.setCredentials({
         accessToken: 'phx_x',
         projectApiKey: 'phc_x',
-        host: 'https://us.posthog.com',
+        host: HostResolution.fromApiHost('https://us.posthog.com'),
         projectId: 1,
       });
     } else if (screen === ScreenId.Run) {

e2e-harness/__tests__/wizard-ci-driver.test.ts

@@ -13,6 +13,7 @@ import { WizardStore } from '@ui/tui/store';
 import { InkUI } from '@ui/tui/ink-ui';
 import { setUI } from '@ui/index';
 import { buildSession, RunPhase, McpOutcome } from '@lib/wizard-session';
+import { HostResolution } from '@lib/host-resolution';
 import { Integration } from '@lib/constants';
 import { FRAMEWORK_REGISTRY } from '@lib/registry';
 import { WizardReadiness } from '@lib/health-checks/readiness';
@@ -72,7 +73,7 @@ describe('WizardCiDriver — full integration flow', () => {
     store.setCredentials({
       accessToken: 'phx_secret_should_not_leak',
       projectApiKey: 'phc_public',
-      host: 'https://us.posthog.com',
+      host: HostResolution.fromApiHost('https://us.posthog.com'),
       projectId: 42,
     });
 
@@ -112,7 +113,7 @@ describe('WizardCiDriver — full integration flow', () => {
     store.setCredentials({
       accessToken: 'phx_secret_should_not_leak',
       projectApiKey: 'phc_public',
-      host: 'https://us.posthog.com',
+      host: HostResolution.fromApiHost('https://us.posthog.com'),
       projectId: 7,
     });
     const state = driver.readState();

src/commands/doctor.ts

@@ -58,7 +58,11 @@ async function runDoctorCI(options: Record<string, unknown>): Promise<void> {
       baseUrl: options.baseUrl as string | undefined,
     });
 
-    const issues = await fetchHealthIssues(accessToken, host, projectId);
+    const issues = await fetchHealthIssues(
+      accessToken,
+      host.apiHost,
+      projectId,
+    );
     if (issues.length === 0) {
       getUI().log.success('No active issues — your project looks healthy.');
       process.exit(0);

src/lib/agent/__tests__/agent-prompt-loader.test.ts

@@ -13,6 +13,7 @@ import {
   type OrchestratorPromptContext,
 } from '../agent-prompt-loader';
 import { QueueStore } from '@lib/agent/runner/orchestrator/queue';
+import { HostResolution } from '@lib/host-resolution';
 
 function tmpDir(): string {
   return fs.mkdtempSync(path.join(os.tmpdir(), 'agent-loader-test-'));
@@ -280,7 +281,7 @@ describe('assembleTaskPrompt', () => {
   const ctx: OrchestratorPromptContext = {
     projectId: 1,
     projectApiKey: 'phc_x',
-    host: 'https://us.posthog.com',
+    host: HostResolution.fromApiHost('https://us.posthog.com'),
   };
 
   it('points the agent at its installed task instructions', () => {

src/lib/agent/__tests__/agent-prompt.test.ts

@@ -1,5 +1,6 @@
 import { assemblePrompt, type PromptContext } from '@lib/agent/agent-prompt';
 import type { ProgramRun } from '@lib/agent/agent-runner';
+import { HostResolution } from '@lib/host-resolution';
 
 function makeRunDef(overrides: Partial<ProgramRun> = {}): ProgramRun {
   return {
@@ -16,7 +17,7 @@ function makeRunDef(overrides: Partial<ProgramRun> = {}): ProgramRun {
 const baseCtx: PromptContext = {
   projectId: 42,
   projectApiKey: 'phc_test123',
-  host: 'https://app.posthog.com',
+  host: HostResolution.fromApiHost('https://app.posthog.com'),
 };
 
 describe('assemblePrompt', () => {

src/lib/agent/agent-interface.ts

@@ -25,7 +25,7 @@ import {
 } from '@lib/wizard-session';
 import { wizardAbort, WizardError } from '@utils/wizard-abort';
 import { createCustomHeaders } from '@utils/custom-headers';
-import { HostResolution } from '@lib/host-resolution';
+import type { HostResolution } from '@lib/host-resolution';
 import { LINTING_TOOLS } from '@lib/safe-tools';
 import { createWizardToolsServer, WIZARD_TOOL_NAMES } from '@lib/wizard-tools';
 import {
@@ -176,7 +176,7 @@ export type AgentConfig = {
   workingDirectory: string;
   posthogMcpUrl: string;
   posthogApiKey: string;
-  posthogApiHost: string;
+  host: HostResolution;
   additionalMcpServers?: Record<string, { url: string }>;
   detectPackageManager: PackageManagerDetector;
   /** Base URL for the skills server (context-mill dev or GitHub releases) */
@@ -630,16 +630,12 @@ export async function initializeAgent(
   logToFile('Install directory:', options.installDir);
 
   try {
-    // TODO: clean up in #755
-    const gatewayUrl = HostResolution.fromApiHost(
-      config.posthogApiHost,
-    ).gatewayUrl;
-
     // Configure model routing (inherited by the SDK subprocess). All model
     // calls route through the PostHog LLM gateway, authed with the user's
     // OAuth token.
     // Disable experimental betas (like input_examples) the gateway doesn't support.
     process.env.CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS = 'true';
+    const gatewayUrl = config.host.gatewayUrl;
     process.env.ANTHROPIC_BASE_URL = gatewayUrl;
     process.env.ANTHROPIC_AUTH_TOKEN = config.posthogApiKey;
 

src/lib/agent/agent-prompt-loader.ts

@@ -17,6 +17,7 @@
  */
 import type { QueueStore, QueuedTask } from './runner/orchestrator/queue';
 import type { ResolvedTask } from './runner/orchestrator/executor';
+import type { HostResolution } from '@lib/host-resolution';
 
 /**
  * The basics the client injects around every agent-prompt body. The `/agents/`
@@ -27,7 +28,7 @@ import type { ResolvedTask } from './runner/orchestrator/executor';
 export interface OrchestratorPromptContext {
   projectId: number;
   projectApiKey: string;
-  host: string;
+  host: HostResolution;
   /** Path to the framework's reference implementation (EXAMPLE.md), if available. */
   examplePath?: string;
   /** Path to the framework's rules (COMMANDMENTS.md), if available. */
@@ -40,7 +41,7 @@ function projectContext(ctx: OrchestratorPromptContext): string {
 Project context:
 - PostHog Project ID: ${ctx.projectId}
 - PostHog public token: ${ctx.projectApiKey}
-- PostHog Host: ${ctx.host}`;
+- PostHog Host: ${ctx.host.apiHost}`;
 }
 
 /** Points the agent at the framework's reference integration to learn patterns from. */

src/lib/agent/agent-prompt.ts

@@ -8,14 +8,15 @@
  */
 
 import type { ProgramRun } from './agent-runner.js';
+import type { HostResolution } from '@lib/host-resolution';
 
 /**
  * Values available to prompt builders after OAuth completes.
  */
 export interface PromptContext {
   projectId: number;
   projectApiKey: string;
-  host: string;
+  host: HostResolution;
   /** Set when skillId was provided and the skill was installed successfully. */
   skillPath?: string;
   /**
@@ -44,7 +45,7 @@ function defaultProjectPrompt(ctx: PromptContext): string {
 Project context:
 - PostHog Project ID: ${ctx.projectId}
 - PostHog public token: ${ctx.projectApiKey}
-- PostHog Host: ${ctx.host}`;
+- PostHog Host: ${ctx.host.apiHost}`;
 }
 
 function skillPrompt(skillPath: string, reportFile: string): string {

src/lib/agent/mcp-prompt-streaming.ts

@@ -15,8 +15,6 @@
 import type { AgentChunk } from '@ui/tui/services/mcp-suggested-prompts-services';
 import type { Credentials } from '@lib/wizard-session';
 import { WIZARD_USER_AGENT } from '@lib/constants';
-import { HostResolution } from '@lib/host-resolution';
-import { runtimeEnv } from '@env';
 import { logToFile } from '@utils/debug';
 import { buildAgentEnv } from '@lib/agent/agent-interface';
 import { sanitizeAgentSubprocessEnv } from '@lib/agent/agent-env-isolation';
@@ -43,13 +41,6 @@ const MODEL = 'claude-sonnet-4-6';
 // telemetry on average turn counts per prompt.
 const MAX_TURNS = 30;
 
-// One MCP url for every region: the server resolves the user's region from
-// the bearer token, so the EU subdomain (a Claude Code OAuth workaround) is
-// not needed here.
-function resolveMcpUrl(): string {
-  return runtimeEnv('MCP_URL') || 'https://mcp.posthog.com/mcp';
-}
-
 /**
  * Extract a short, single-line summary from an arbitrary value. Used
  * for tool-call args and tool-result bodies so the screen has something
@@ -198,8 +189,7 @@ export async function* runMcpPromptViaSdk(args: {
   process.env.CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS = 'true';
 
   // Route through the PostHog LLM gateway, authed with the user's OAuth token.
-  // TODO: clean up in #755
-  const gatewayUrl = HostResolution.fromApiHost(credentials.host).gatewayUrl;
+  const gatewayUrl = credentials.host.gatewayUrl;
   process.env.ANTHROPIC_BASE_URL = gatewayUrl;
   process.env.ANTHROPIC_AUTH_TOKEN = credentials.accessToken;
   process.env.CLAUDE_CODE_OAUTH_TOKEN = credentials.accessToken;
@@ -223,7 +213,7 @@ export async function* runMcpPromptViaSdk(args: {
       once: true,
     });
 
-  const mcpUrl = resolveMcpUrl();
+  const mcpUrl = credentials.host.mcpUrl;
   logToFile(
     `[runMcpPromptViaSdk] mcpUrl=${mcpUrl} model=${MODEL} resume=${
       resumeSessionId ?? '(none)'

src/lib/agent/runner/linear.ts

@@ -15,7 +15,6 @@ import {
   AgentSignals,
 } from '../agent-interface';
 import { restoreClaudeSettings } from '../claude-settings';
-import { HostResolution } from '@lib/host-resolution';
 import { logToFile, getLogFilePath } from '../../../utils/debug';
 import { createBenchmarkPipeline } from '../../middleware/benchmark';
 import {
@@ -45,18 +44,10 @@ export async function runLinearProgram(
   boot: BootstrapResult,
   composed = false,
 ): Promise<void> {
-  const {
-    skillsBaseUrl,
-    projectApiKey,
-    host,
-    accessToken,
-    projectId,
-    cloudRegion,
-    mcpUrl,
-    wizardFlags,
-    wizardMetadata,
-    project,
-  } = boot;
+  const { skillsBaseUrl, wizardFlags, wizardMetadata, project } = boot;
+  // Set by bootstrapProgram before the fork — guaranteed non-null here.
+  const credentials = session.credentials!;
+  const { projectApiKey, host, accessToken, projectId } = credentials;
 
   // 5. Skill install (if skillId provided)
   let skillPath: string | undefined;
@@ -110,9 +101,9 @@ export async function runLinearProgram(
   const agent = await initializeAgent(
     {
       workingDirectory: session.installDir,
-      posthogMcpUrl: mcpUrl,
+      posthogMcpUrl: host.mcpUrl,
       posthogApiKey: accessToken,
-      posthogApiHost: host,
+      host,
       additionalMcpServers: config.additionalMcpServers,
       detectPackageManager:
         config.detectPackageManager ?? detectNodePackageManagers,
@@ -267,12 +258,7 @@ export async function runLinearProgram(
 
   // 10. Post-run hooks
   if (config.postRun) {
-    await config.postRun(session, {
-      accessToken,
-      projectApiKey,
-      host,
-      projectId,
-    });
+    await config.postRun(session, credentials);
   }
 
   // A composed sub-run (integration inside self-driving) skips the terminal
@@ -288,23 +274,14 @@ export async function runLinearProgram(
   // that the screen never reads. UI.setOutroData() goes through the store
   // and also merges in any post-snapshot URLs from the live session.
   const outroData = config.buildOutroData
-    ? config.buildOutroData(
-        session,
-        { accessToken, projectApiKey, host, projectId },
-        cloudRegion,
-      )
+    ? config.buildOutroData(session, credentials)
     : {
         kind: OutroKind.Success,
         message: config.successMessage,
         reportFile: config.reportFile,
         docsUrl: config.docsUrl,
-        // TODO: clean up in #755
         continueUrl: session.signup
-          ? `${
-              HostResolution.fromRegion(cloudRegion, {
-                baseUrl: session.baseUrl,
-              }).appHost
-            }/products?source=wizard`
+          ? `${host.appHost}/products?source=wizard`
           : undefined,
       };
   if (outroData) {

src/lib/agent/runner/orchestrator/orchestrator-runner.ts

@@ -105,6 +105,9 @@ export async function runOrchestrator(
 
   const options = sessionRunOptions(session);
 
+  // Set by bootstrapProgram before the fork — guaranteed non-null here.
+  const credentials = session.credentials!;
+
   // The WHAT (agent prompts) is served from context-mill. Fetch the registry
   // once up front: its types drive enqueue validation, and resolving a task to
   // its run config is then synchronous, with no mid-drain network latency.
@@ -219,9 +222,9 @@ export async function runOrchestrator(
   // The client injects the basics (project context + the I/O contract) around
   // every authored agent-prompt body.
   const promptContext: OrchestratorPromptContext = {
-    projectId: boot.projectId,
-    projectApiKey: boot.projectApiKey,
-    host: boot.host,
+    projectId: credentials.projectId,
+    projectApiKey: credentials.projectApiKey,
+    host: credentials.host,
     examplePath,
     commandmentsPath,
   };
@@ -253,9 +256,9 @@ export async function runOrchestrator(
   // so its context has no task id.
   const agentConfigFor = (currentTaskId?: string): AgentConfig => ({
     workingDirectory: session.installDir,
-    posthogMcpUrl: boot.mcpUrl,
-    posthogApiKey: boot.accessToken,
-    posthogApiHost: boot.host,
+    posthogMcpUrl: credentials.host.mcpUrl,
+    posthogApiKey: credentials.accessToken,
+    host: credentials.host,
     detectPackageManager: detectNodePackageManagers,
     skillsBaseUrl: boot.skillsBaseUrl,
     wizardFlags: boot.wizardFlags,

src/lib/agent/runner/shared/authenticate.ts

@@ -29,7 +29,6 @@ export async function authenticate(
     host,
     accessToken,
     projectId,
-    cloudRegion,
     roleAtOrganization,
     user,
     project,
@@ -41,11 +40,11 @@ export async function authenticate(
     email: session.email,
     region: session.region,
     baseUrl: session.baseUrl,
+    localMcp: session.localMcp,
     programId,
   });
 
   session.credentials = { accessToken, projectApiKey, host, projectId };
-  session.cloudRegion = cloudRegion;
   session.apiProject = project;
   session.roleAtOrganization = roleAtOrganization;
   session.apiUser = user;
@@ -57,5 +56,5 @@ export async function authenticate(
   // Identify the user (email, name) before flags are evaluated, so flags can
   // target the individual user and not just $app_name.
   if (user) analytics.identifyUser(user);
-  analytics.setGroups(groupsFromUser(user, host));
+  analytics.setGroups(groupsFromUser(user, host.apiHost));
 }