feat(agent): wire up hog (pi) as a selectable runtime adapter

packages/agent/e2e/config.ts

@@ -55,6 +55,9 @@ export const E2E = {
     if (adapter === "claude") {
       return process.env.POSTHOG_CODE_E2E_CLAUDE_MODEL || "claude-haiku-4-5";
     }
+    if (adapter === "hog") {
+      return process.env.POSTHOG_CODE_E2E_HOG_MODEL || "claude-haiku-4-5";
+    }
     // gpt-5-mini is on the product block list, but that gate is only enforced in
     // Agent.run — the e2e drives createAcpConnection directly, so it's accepted.
     return process.env.POSTHOG_CODE_E2E_CODEX_MODEL || "gpt-5-mini";
@@ -71,6 +74,11 @@ export const E2E = {
         process.env.POSTHOG_CODE_E2E_CLAUDE_STRONG_MODEL || "claude-sonnet-4-5"
       );
     }
+    if (adapter === "hog") {
+      return (
+        process.env.POSTHOG_CODE_E2E_HOG_STRONG_MODEL || "claude-sonnet-4-5"
+      );
+    }
     return process.env.POSTHOG_CODE_E2E_CODEX_STRONG_MODEL || "gpt-5.5";
   },
 
@@ -85,7 +93,7 @@ export const E2E = {
 
   /** Point the adapter at the gateway as the host's `configureEnvironment` does. */
   configureEnv(adapter: Adapter): void {
-    if (adapter === "claude") {
+    if (adapter === "claude" || adapter === "hog") {
       process.env.ANTHROPIC_BASE_URL = GATEWAY_URL;
       process.env.ANTHROPIC_AUTH_TOKEN = TOKEN;
       return;
@@ -94,6 +102,14 @@ export const E2E = {
     process.env.OPENAI_API_KEY = TOKEN;
   },
 
+  /** The hogGateway config the hog arm passes through `createAcpConnection`. */
+  hogGateway(): { gatewayUrl: string; apiKey: string } {
+    return {
+      gatewayUrl: GATEWAY_URL,
+      apiKey: TOKEN,
+    };
+  },
+
   /** The codexOptions the codex arm passes through `createAcpConnection`. */
   codexOptions(
     cwd: string,

packages/agent/e2e/driver.ts

@@ -86,6 +86,7 @@ export function openConnection(opts: {
   adapter: Adapter;
   cwd: string;
   codexOptions?: Record<string, unknown>;
+  hogGateway?: { gatewayUrl: string; apiKey: string };
   onStructuredOutput?: (output: Record<string, unknown>) => Promise<void>;
 }): E2EConnection {
   const { adapter, cwd } = opts;
@@ -142,6 +143,7 @@ export function openConnection(opts: {
   const acp = createAcpConnection({
     adapter,
     codexOptions: opts.codexOptions as any,
+    hogGateway: opts.hogGateway,
     onStructuredOutput: opts.onStructuredOutput,
     logger,
   });
@@ -196,6 +198,7 @@ export async function openSession(opts: {
   adapter: Adapter;
   cwd: string;
   codexOptions?: Record<string, unknown>;
+  hogGateway?: { gatewayUrl: string; apiKey: string };
   onStructuredOutput?: (output: Record<string, unknown>) => Promise<void>;
   meta: Record<string, unknown>;
 }): Promise<OpenSession> {

packages/agent/e2e/session-lifecycle.e2e.test.ts

@@ -20,7 +20,7 @@ import {
  * invariants + the on-disk edit, never model prose. Opt-in: each arm self-skips
  * unless `POSTHOG_CODE_E2E_GATEWAY_PERSONAL_API_KEY` is set (codex also needs the native binary).
  */
-const ADAPTERS: Adapter[] = ["claude", "codex"];
+const ADAPTERS: Adapter[] = ["claude", "codex", "hog"];
 
 const EDIT_PROMPT =
   "Do exactly these steps and nothing else: 1) Read the file target.txt. " +
@@ -31,8 +31,10 @@ const EDIT_PROMPT =
 for (const adapter of ADAPTERS) {
   const skip = E2E.skipReason(adapter);
   const title = `session lifecycle (${adapter})${skip ? ` — SKIPPED (${skip})` : ""}`;
-  // Codex-only; skipped on the claude arm so the gap is visible.
+  // Adapter-specific coverage where the other harnesses do not implement the feature.
   const itCodex = adapter === "codex" ? it : it.skip;
+  const itWithModes = adapter !== "hog" ? it : it.skip;
+  const itNativeSteer = adapter === "codex" || adapter === "hog" ? it : it.skip;
   // Read-only profile only tightens per-turn on macOS + non-cloud (elsewhere the
   // spawn is danger-full-access / no profile), so gate to where it actually applies.
   const itCodexSandbox =
@@ -46,6 +48,7 @@ for (const adapter of ADAPTERS) {
     let repo: string;
     const codexOptions = () =>
       adapter === "codex" ? E2E.codexOptions(repo) : undefined;
+    const hogGateway = () => (adapter === "hog" ? E2E.hogGateway() : undefined);
     const meta = (extra: Record<string, unknown> = {}) => ({
       systemPrompt: "You are a coding assistant in a tiny test repo.",
       model: E2E.model(adapter),
@@ -69,6 +72,7 @@ for (const adapter of ADAPTERS) {
         adapter,
         cwd: repo,
         codexOptions: codexOptions(),
+        hogGateway: hogGateway(),
         meta: meta(),
       });
       sessionId = s.sessionId;
@@ -153,6 +157,7 @@ for (const adapter of ADAPTERS) {
         adapter,
         cwd: repo,
         codexOptions: codexOptions(),
+        hogGateway: hogGateway(),
         meta: meta(),
       });
       try {
@@ -190,37 +195,42 @@ for (const adapter of ADAPTERS) {
       }
     }, 90_000);
 
-    // Cloud host switches mode only via setSessionConfigOption(configId:"mode"), so exercise both arms.
-    it("emits current_mode_update when the mode is switched via setSessionConfigOption", async () => {
-      const s = await openSession({
-        adapter,
-        cwd: repo,
-        codexOptions: codexOptions(),
-        meta: meta(),
-      });
-      try {
-        // codex synthesizes modes; claude exposes a "mode" configOption — pick an alternate value.
-        let value = "read-only";
-        if (adapter === "claude") {
-          const modeOpt = (s.newSession.configOptions ?? []).find(
-            (o) => o.id === "mode",
-          );
-          value =
-            (modeOpt?.options?.find((v) => v.value !== modeOpt.currentValue)
-              ?.value as string) ?? "plan";
-        }
-        await s.conn.setSessionConfigOption({
-          sessionId: s.sessionId,
-          configId: "mode",
-          value,
+    // Cloud host switches mode only via setSessionConfigOption(configId:"mode"), so exercise every harness that exposes a mode picker.
+    itWithModes(
+      "emits current_mode_update when the mode is switched via setSessionConfigOption",
+      async () => {
+        const s = await openSession({
+          adapter,
+          cwd: repo,
+          codexOptions: codexOptions(),
+          hogGateway: hogGateway(),
+          meta: meta(),
         });
-        expect(s.capture.updates("current_mode_update").length).toBeGreaterThan(
-          0,
-        );
-      } finally {
-        await s.cleanup();
-      }
-    }, 60_000);
+        try {
+          // codex synthesizes modes; claude exposes a "mode" configOption — pick an alternate value.
+          let value = "read-only";
+          if (adapter === "claude") {
+            const modeOpt = (s.newSession.configOptions ?? []).find(
+              (o) => o.id === "mode",
+            );
+            value =
+              (modeOpt?.options?.find((v) => v.value !== modeOpt.currentValue)
+                ?.value as string) ?? "plan";
+          }
+          await s.conn.setSessionConfigOption({
+            sessionId: s.sessionId,
+            configId: "mode",
+            value,
+          });
+          expect(
+            s.capture.updates("current_mode_update").length,
+          ).toBeGreaterThan(0);
+        } finally {
+          await s.cleanup();
+        }
+      },
+      60_000,
+    );
 
     // Proves the mode picker isn't cosmetic: read-only maps to an OS-level
     // :read-only profile that blocks the write even though the host auto-approves.
@@ -322,6 +332,7 @@ for (const adapter of ADAPTERS) {
         adapter,
         cwd: repo,
         codexOptions: codexOptions(),
+        hogGateway: hogGateway(),
         meta: meta(),
       });
       try {
@@ -351,6 +362,7 @@ for (const adapter of ADAPTERS) {
         adapter,
         cwd: repo,
         codexOptions: codexOptions(),
+        hogGateway: hogGateway(),
         meta: meta(),
       });
       try {
@@ -377,7 +389,7 @@ for (const adapter of ADAPTERS) {
       }
     }, 120_000);
 
-    itCodex(
+    itNativeSteer(
       "folds a mid-turn prompt into the running turn via steering",
       async () => {
         const s = await openSession({
@@ -431,13 +443,14 @@ for (const adapter of ADAPTERS) {
       120_000,
     );
 
-    itCodex(
+    itNativeSteer(
       "lists the session and forks it",
       async () => {
         const b = openConnection({
           adapter,
           cwd: repo,
           codexOptions: codexOptions(),
+          hogGateway: hogGateway(),
         });
         try {
           await b.conn.initialize(INIT_PARAMS);
@@ -468,6 +481,7 @@ for (const adapter of ADAPTERS) {
         adapter,
         cwd: repo,
         codexOptions: codexOptions(),
+        hogGateway: hogGateway(),
         meta: meta(),
       });
       try {
@@ -509,6 +523,7 @@ for (const adapter of ADAPTERS) {
         adapter,
         cwd: repo,
         codexOptions: codexOptions(),
+        hogGateway: hogGateway(),
       });
       try {
         await b.conn.initialize(INIT_PARAMS);
@@ -530,6 +545,7 @@ for (const adapter of ADAPTERS) {
         adapter,
         cwd: repo,
         codexOptions: codexOptions(),
+        hogGateway: hogGateway(),
       });
       try {
         await b.conn.initialize(INIT_PARAMS);

packages/agent/package.json

@@ -146,6 +146,7 @@
     "jsonwebtoken": "^9.0.2",
     "minimatch": "^10.0.3",
     "@modelcontextprotocol/sdk": "1.29.0",
+    "@posthog/harness": "workspace:*",
     "tar": "^7.5.0",
     "uuid": "13.0.0",
     "yoga-wasm-web": "^0.3.3",

packages/agent/src/adapters/acp-connection.ts

@@ -13,6 +13,12 @@ import type { GatewayEnv } from "./claude/session/options";
 import { nativeCodexBinaryPath } from "./codex-app-server/binary-path";
 import { CodexAppServerAgent } from "./codex-app-server/codex-app-server-agent";
 import type { CodexOptions } from "./codex-app-server/spawn";
+import { HarnessAcpAgent } from "./harness/harness-agent";
+
+export interface HogGatewayOptions {
+  gatewayUrl?: string;
+  apiKey?: string;
+}
 
 export type AcpConnectionConfig = {
   adapter?: Adapter;
@@ -33,6 +39,8 @@ export type AcpConnectionConfig = {
   enricherEnabled?: boolean;
   /** Explicit gateway config for the Claude adapter — prevents global process.env mutation. */
   claudeGatewayEnv?: GatewayEnv;
+  /** Explicit gateway config for the hog adapter. */
+  hogGateway?: HogGatewayOptions;
 };
 
 export type AcpConnection = {
@@ -58,6 +66,10 @@ export function createAcpConnection(
     return createCodexConnection(config);
   }
 
+  if (adapterType === "hog") {
+    return createHogConnection(config);
+  }
+
   return createClaudeConnection(config);
 }
 
@@ -68,6 +80,86 @@ function resolveEnricherApiConfig(
   return enabled ? config.posthogApiConfig : undefined;
 }
 
+function createHogConnection(config: AcpConnectionConfig): AcpConnection {
+  const logger =
+    config.logger?.child("HogConnection") ??
+    new Logger({ debug: true, prefix: "[HogConnection]" });
+  const streams = createBidirectionalStreams();
+
+  const { logWriter } = config;
+
+  let agentWritable = streams.agent.writable;
+  let clientWritable = streams.client.writable;
+
+  if (config.taskRunId && logWriter) {
+    if (!logWriter.isRegistered(config.taskRunId)) {
+      logWriter.register(config.taskRunId, {
+        taskId: config.taskId ?? config.taskRunId,
+        runId: config.taskRunId,
+        deviceType: config.deviceType,
+      });
+    }
+
+    const taskRunId = config.taskRunId;
+    agentWritable = createTappedWritableStream(streams.agent.writable, {
+      onMessage: (line) => {
+        logWriter.appendRawLine(taskRunId, line);
+      },
+      logger,
+    });
+
+    clientWritable = createTappedWritableStream(streams.client.writable, {
+      onMessage: (line) => {
+        logWriter.appendRawLine(taskRunId, line);
+      },
+      logger,
+    });
+  } else {
+    logger.info("Tapped streams NOT enabled for Hog", {
+      hasTaskRunId: !!config.taskRunId,
+      hasLogWriter: !!logWriter,
+    });
+  }
+
+  const agentStream = ndJsonStream(agentWritable, streams.agent.readable);
+
+  let agent: HarnessAcpAgent | null = null;
+  const agentConnection = new AgentSideConnection((client) => {
+    agent = new HarnessAcpAgent(client, {
+      allowedModelIds: config.allowedModelIds,
+      gatewayUrl: config.hogGateway?.gatewayUrl,
+      apiKey: config.hogGateway?.apiKey,
+    });
+    return agent;
+  }, agentStream);
+
+  return {
+    agentConnection,
+    clientStreams: {
+      readable: streams.client.readable,
+      writable: clientWritable,
+    },
+    cleanup: async () => {
+      logger.info("Cleaning up Hog connection");
+
+      if (agent) {
+        await agent.closeSession();
+      }
+
+      try {
+        await streams.client.writable.close();
+      } catch {
+        // Stream may already be closed
+      }
+      try {
+        await streams.agent.writable.close();
+      } catch {
+        // Stream may already be closed
+      }
+    },
+  };
+}
+
 function createClaudeConnection(config: AcpConnectionConfig): AcpConnection {
   const logger =
     config.logger?.child("AcpConnection") ??