diff --git a/lib/tui/session.mjs b/lib/tui/session.mjs
index 3514cff..00c1fa6 100644
--- a/lib/tui/session.mjs
+++ b/lib/tui/session.mjs
@@ -185,17 +185,28 @@ export function resolveTuiEntrypointEnv(env, mode = "cli") {
 // A-PATH ONLY: built-in tools are left enabled (acceptable single-user). Deployment B
 // (guest keys) MUST additionally pass --tools "" per spec §5.2(2) as the credential
 // wall before this argv is reachable for owner_tier=guest — guard that in PR-3 wiring.
-function buildTuiCmd(claudeBin, model, sessionId, ehome, entrypointMode) {
+export function buildTuiCmd(claudeBin, model, sessionId, ehome, entrypointMode) {
   // Deliver claude's env via an `env` prefix on the PANE COMMAND — tmux does NOT forward the
   // spawning process's environment to the pane, and `new-session -e` needs tmux ≥3.2 (the cloud
   // host runs 2.7), so this is the only portable, reliable mechanism (verified live 2026-06-01:
   // passing {env} to spawnSync left the pane with only HOME). DISABLE_AUTOUPDATER pins the version
   // (no "What's new" splash that delayed input-readiness); CLAUDE_CODE_ENTRYPOINT labels the
   // billing pool (set below per entrypointMode).
+  //
+  // CLAUDE_CODE_DISABLE_CLAUDE_MDS + DISABLE_AUTO_MEMORY: OCP is a PROXY, not a Claude Code
+  // session. The proxied client (OpenClaw / an IDE) owns its own context and memory; the HOST's
+  // CLAUDE.md and auto-memory must NEVER leak into the agent OCP runs on the user's behalf.
+  // Without these, claude loads the host's project/user CLAUDE.md + memory into every proxied
+  // turn — verified live 2026-06-02: a cwd CLAUDE.md ("end every reply with QUACKMARKER_42") was
+  // obeyed by the proxied turn until these flags were set, after which it was not. Unconditional
+  // by design (not gated): proxy purity is not an opt-in. Harmless on hosts with no CLAUDE.md
+  // (the common case — they suppress nothing). Mirrors the -p path's CLAUDE_NO_CONTEXT vars.
   const sets = [
     `HOME=${shq(ehome)}`,
     "DISABLE_AUTOUPDATER=1",
     "CLAUDE_CODE_DISABLE_OFFICIAL_MARKETPLACE_AUTOINSTALL=1",
+    "CLAUDE_CODE_DISABLE_CLAUDE_MDS=1",
+    "CLAUDE_CODE_DISABLE_AUTO_MEMORY=1",
   ];
   const unset = ["CLAUDECODE", "ANTHROPIC_API_KEY", "ANTHROPIC_BASE_URL", "ANTHROPIC_AUTH_TOKEN"];
   if (entrypointMode === "cli") sets.push("CLAUDE_CODE_ENTRYPOINT=cli");
diff --git a/test-features.mjs b/test-features.mjs
index 398f29b..0afb1a5 100644
--- a/test-features.mjs
+++ b/test-features.mjs
@@ -1478,7 +1478,7 @@ await asyncTest("readTuiTranscript throws when no text and cap elapses", async (
 });
 
 // ── TUI session reaper ───────────────────────────────────────────────────
-import { reapStaleTuiSessions, SESSION_PREFIX } from "./lib/tui/session.mjs";
+import { reapStaleTuiSessions, SESSION_PREFIX, buildTuiCmd } from "./lib/tui/session.mjs";
 
 console.log("\nTUI session reaper:");
 
@@ -1486,6 +1486,26 @@ test("SESSION_PREFIX is ocp-tui-", () => {
   assert.equal(SESSION_PREFIX, "ocp-tui-");
 });
 
+console.log("\nTUI command construction (proxy-purity / #4):");
+
+test("buildTuiCmd suppresses host CLAUDE.md + auto-memory (proxy purity, #4)", () => {
+  const cmd = buildTuiCmd("/usr/bin/claude", "claude-haiku", "sid-1", "/home/u", "cli");
+  // OCP is a proxy: the host's CLAUDE.md / auto-memory must never leak into the proxied turn.
+  assert.ok(/(^| )CLAUDE_CODE_DISABLE_CLAUDE_MDS=1( |$)/.test(cmd), "must disable CLAUDE.md injection");
+  assert.ok(/(^| )CLAUDE_CODE_DISABLE_AUTO_MEMORY=1( |$)/.test(cmd), "must disable auto-memory injection");
+});
+
+test("buildTuiCmd keeps version pin + entrypoint label + MCP wall", () => {
+  const cli = buildTuiCmd("/usr/bin/claude", "m", "sid-2", "/home/u", "cli");
+  assert.ok(cli.includes("DISABLE_AUTOUPDATER=1"), "version pin retained");
+  assert.ok(cli.includes("CLAUDE_CODE_ENTRYPOINT=cli"), "cli mode labels the subscription pool");
+  assert.ok(cli.includes("--strict-mcp-config") && cli.includes('mcp__*'), "MCP wall retained");
+  // 'auto' mode must NOT pin the entrypoint (claude self-classifies via TTY).
+  const auto = buildTuiCmd("/usr/bin/claude", "m", "sid-3", "/home/u", "auto");
+  assert.ok(!/CLAUDE_CODE_ENTRYPOINT=/.test(auto), "auto mode leaves entrypoint unset");
+  assert.ok(/-u CLAUDE_CODE_ENTRYPOINT/.test(auto), "auto mode unsets any inherited entrypoint");
+});
+
 test("reaper kills ONLY ocp-tui- sessions, never olp-tui-", () => {
   const killed = [];
   const fakeTmux = (args) => {