diff --git a/tests/runner-e2e/docker-postgres.test.ts b/tests/runner-e2e/docker-postgres.test.ts
index f352d52cab9..650a27a9bed 100644
--- a/tests/runner-e2e/docker-postgres.test.ts
+++ b/tests/runner-e2e/docker-postgres.test.ts
@@ -9,7 +9,9 @@ import { assertRunnerDatabaseIsolation, assertEmbeddedDatabaseIsolation } from "
 import { campaignDatabaseEvidenceEligible, type CampaignAttempt } from "./chat-campaign.js";
 import { assertChatCatalogFingerprintLane, fingerprintChatDependencyClosure } from "./chat-catalog-fingerprint.js";
 import { validateRetainedRunnerResult } from "./result-validation.js";
-import { buildPaperclipServerEnvironment } from "./harness-env.js";
+import { assertIsolatedServerEnvironment, buildPaperclipServerEnvironment } from "./harness-env.js";
+import { findSecretLeakInDirectory } from "./redaction.js";
+import { createSanitizedCodexEnvironment } from "../../packages/paperclip-runner/src/drivers/codex/app-server-transport.js";
 const roots: string[] = [];
 beforeEach(() => { vi.stubEnv("DOCKER_HOST", ""); vi.stubEnv("DOCKER_CONTEXT", ""); });
 afterEach(async () => { vi.unstubAllEnvs(); for (const root of roots.splice(0)) await rm(root, { recursive: true, force: true }); });
@@ -71,7 +73,10 @@ it("binds exact image/engine/resources, strips admission data and removes only o
   expect(supervisor.source[DOCKER_DATABASE_ENV]).toBeUndefined(); expect(supervisor.source[DATABASE_LANE_ENV]).toBeUndefined();
   const configPath = path.join(temp, "paperclip-home", "instances", "fixture", "config.json");
   expect(await prepareRunnerE2EServerConfig({ temporaryRoot: temp, configPath, serverPort: 3100, dockerReceiptPath: owned.filename, dockerRun: run })).toBeNull();
-  const config = JSON.parse(await readFile(configPath, "utf8")); expect(config.database.mode).toBe("postgres"); expect(config.database.connectionString).toBe(owned.receipt.connectionString);
+  const config = JSON.parse(await readFile(configPath, "utf8")); expect(config.database.mode).toBe("postgres"); expect(config.database.connectionString).toBeUndefined();
+  expect(JSON.stringify(config)).not.toContain(secrets[0]);
+  expect(supervisor.serverOverrides.DATABASE_URL).toBe(owned.receipt.connectionString);
+  expect(supervisor.source.DATABASE_URL).toBeUndefined();
   const key = config.secrets.localEncrypted.keyFilePath; await mkdir(path.dirname(key), { recursive: true }); await writeFile(key, "offline-key", { mode: 0o600 });
   await expect(assertRunnerDatabaseIsolation(configPath, temp, owned.filename, run)).resolves.toBeUndefined();
   const changed = structuredClone(config); changed.database.connectionString = "postgresql://foreign"; await writeFile(configPath, JSON.stringify(changed), { mode: 0o600 });
@@ -183,3 +188,34 @@ it("allows only exact Docker Desktop host translation with an owned canonical pr
   await rm(password); await writeFile(password, contents, { mode: 0o600 });
   await owned.close(); expect(state.container).toBeNull(); expect(state.volume).toBeNull();
 });
+
+it("keeps owned DB credentials server-only without any persisted scan exemption", async () => {
+  const temp = await root(), { run } = daemon(), secrets: string[] = [];
+  const owned = await startOwnedDockerDatabase({ temporaryRoot: temp, privateSecrets: secrets, run });
+  const admission = await dockerDatabaseSupervisorEnvironment({ temporaryRoot: temp, env: { [DATABASE_LANE_ENV]: "owned-docker-postgres", [DOCKER_DATABASE_ENV]: owned.filename, DATABASE_URL: "ambient-unrelated", DATABASE_MIGRATION_URL: "ambient-migration" }, run });
+  const home = path.join(temp, "paperclip-home"), configPath = path.join(home, "instances", "custody", "config.json");
+  await prepareRunnerE2EServerConfig({ temporaryRoot: temp, configPath, serverPort: 3100, dockerReceiptPath: owned.filename, dockerRun: run });
+  const expected = { temporaryRoot: temp, paperclipHome: home, configPath, ownedDatabaseUrl: admission.serverOverrides.DATABASE_URL };
+  const env = buildPaperclipServerEnvironment(admission.source, { ...admission.serverOverrides, PAPERCLIP_HOME: home, PAPERCLIP_CONFIG: configPath, XDG_CACHE_HOME: path.join(temp, "xdg-cache"), PAPERCLIP_AGENT_JWT_SECRET: "jwt", PAPERCLIP_DECISION_SIGNING_SECRET: "decision", PAPERCLIP_TOOL_ACTION_SIGNING_SECRET: "tool", BETTER_AUTH_SECRET: "auth" });
+  expect(env.DATABASE_URL).toBe(owned.receipt.connectionString);
+  expect(env.DATABASE_MIGRATION_URL).toBeUndefined();
+  expect(() => assertIsolatedServerEnvironment(env, expected)).not.toThrow();
+  expect(() => assertIsolatedServerEnvironment({ ...env, DATABASE_URL: "ambient-unrelated" }, expected)).toThrow();
+  expect(() => assertIsolatedServerEnvironment(env, { ...expected, ownedDatabaseUrl: undefined })).toThrow();
+  expect(createSanitizedCodexEnvironment(env).DATABASE_URL).toBeUndefined();
+  expect(createSanitizedCodexEnvironment(env).DATABASE_MIGRATION_URL).toBeUndefined();
+  expect(await findSecretLeakInDirectory(home, secrets, { includeShapes: false })).toBeNull();
+  const config = JSON.parse(await readFile(configPath, "utf8"));
+  config.database.connectionString = owned.receipt.connectionString;
+  await writeFile(configPath, JSON.stringify(config), { mode: 0o600 });
+  expect(await findSecretLeakInDirectory(home, secrets, { includeShapes: false })).not.toBeNull();
+  await expect(prepareRunnerE2EServerConfig({ temporaryRoot: temp, configPath, serverPort: 3100, dockerReceiptPath: owned.filename, dockerRun: run })).rejects.toThrow("differs");
+  delete config.database.connectionString;
+  config.unrelatedField = secrets[0];
+  await writeFile(configPath, JSON.stringify(config), { mode: 0o600 });
+  expect(await findSecretLeakInDirectory(home, secrets, { includeShapes: false })).not.toBeNull();
+  config.unrelatedField = "provider-secret-canary";
+  await writeFile(configPath, JSON.stringify(config), { mode: 0o600 });
+  expect(await findSecretLeakInDirectory(home, [...secrets, "provider-secret-canary"], { includeShapes: false })).not.toBeNull();
+  await owned.close();
+});
diff --git a/tests/runner-e2e/docker-postgres.ts b/tests/runner-e2e/docker-postgres.ts
index e1fb5ca31c9..60427d5ca10 100644
--- a/tests/runner-e2e/docker-postgres.ts
+++ b/tests/runner-e2e/docker-postgres.ts
@@ -234,11 +234,11 @@ export async function startOwnedDockerDatabase(input: { temporaryRoot: string; p
 export async function dockerDatabaseSupervisorEnvironment(input: { temporaryRoot: string; env: NodeJS.ProcessEnv; run?: DockerRun }) {
   const lane = selectedDatabaseLane(input.env), source = { ...input.env }, filename = source[DOCKER_DATABASE_ENV];
   delete source[DOCKER_DATABASE_ENV]; delete source[DATABASE_LANE_ENV];
-  if (lane === "embedded-postgres") { if (filename) throw new Error("Undeclared Docker database receipt"); return { source, filename: undefined }; }
+  if (lane === "embedded-postgres") { if (filename) throw new Error("Undeclared Docker database receipt"); return { source, filename: undefined, serverOverrides: {} as NodeJS.ProcessEnv }; }
   if (!filename) throw new Error("Selected Docker database lane is missing its owned receipt");
-  await readDockerDatabaseReceipt(filename, input.temporaryRoot, input.run);
+  const receipt = await readDockerDatabaseReceipt(filename, input.temporaryRoot, input.run);
   for (const key of ["DOCKER_CONFIG", "DOCKER_HOST", "DOCKER_CONTEXT"]) delete source[key];
-  return { source, filename };
+  return { source, filename, serverOverrides: { DATABASE_URL: receipt.connectionString } as NodeJS.ProcessEnv };
 }
 
 export function databaseFingerprintIdentity(env = process.env) {
diff --git a/tests/runner-e2e/harness-env.ts b/tests/runner-e2e/harness-env.ts
index af403e887ab..b82dcf3950c 100644
--- a/tests/runner-e2e/harness-env.ts
+++ b/tests/runner-e2e/harness-env.ts
@@ -235,6 +235,8 @@ export function assertIsolatedServerEnvironment(
     temporaryRoot: string;
     paperclipHome: string;
     configPath: string;
+    /** Supplied only after exact owned Docker receipt validation by the supervisor. */
+    ownedDatabaseUrl?: string;
   },
 ) {
   const home = env.PAPERCLIP_HOME;
@@ -263,11 +265,12 @@ export function assertIsolatedServerEnvironment(
     ...AMBIENT_PAPERCLIP_CREDENTIAL_KEYS,
     ...AMBIENT_EXTERNAL_STATE_KEYS,
   ]) {
-    if (env[key])
+    if (env[key] && !(key === "DATABASE_URL" && expected.ownedDatabaseUrl && env[key] === expected.ownedDatabaseUrl))
       throw new Error(
         `Paperclip server environment unexpectedly contains ${key}`,
       );
   }
+  if (expected.ownedDatabaseUrl && env.DATABASE_URL !== expected.ownedDatabaseUrl) throw new Error("Paperclip server database URL differs from the validated owned receipt");
   for (const key of GENERATED_SERVER_SECRET_KEYS) {
     if (!env[key])
       throw new Error(`Paperclip server environment is missing ${key}`);
diff --git a/tests/runner-e2e/instance-isolation.ts b/tests/runner-e2e/instance-isolation.ts
index 0d7e8643228..ab1727c4d9c 100644
--- a/tests/runner-e2e/instance-isolation.ts
+++ b/tests/runner-e2e/instance-isolation.ts
@@ -28,7 +28,7 @@ export async function assertRunnerDatabaseIsolation(
     };
   };
   const docker = dockerReceiptPath ? await readDockerDatabaseReceipt(dockerReceiptPath, temporaryRoot, dockerRun) : undefined;
-  if (docker ? config.database?.mode !== "postgres" || config.database.connectionString !== docker.connectionString : config.database?.mode !== "embedded-postgres" || !!config.database.connectionString) {
+  if (docker ? config.database?.mode !== "postgres" || !!config.database.connectionString : config.database?.mode !== "embedded-postgres" || !!config.database.connectionString) {
     throw new Error("Runner E2E Paperclip instance did not use its explicitly owned database lane");
   }
   if (
diff --git a/tests/runner-e2e/server-config.ts b/tests/runner-e2e/server-config.ts
index d85714e33b7..c586ef25628 100644
--- a/tests/runner-e2e/server-config.ts
+++ b/tests/runner-e2e/server-config.ts
@@ -23,7 +23,7 @@ export async function prepareRunnerE2EServerConfig(input: {
   const docker = input.dockerReceiptPath ? await readDockerDatabaseReceipt(input.dockerReceiptPath, input.temporaryRoot, input.dockerRun) : undefined;
   try {
     const existing = JSON.parse(await readFile(input.configPath, "utf8"));
-    if (docker ? existing.database?.mode !== "postgres" || existing.database.connectionString !== docker.connectionString : existing.database?.mode !== "embedded-postgres" || existing.database.connectionString) throw new Error("Existing runner database config differs from its explicit owned lane");
+    if (docker ? existing.database?.mode !== "postgres" || !!existing.database.connectionString : existing.database?.mode !== "embedded-postgres" || existing.database.connectionString) throw new Error("Existing runner database config differs from its explicit owned lane");
     return null;
   } catch (error) {
     if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
@@ -37,9 +37,10 @@ export async function prepareRunnerE2EServerConfig(input: {
         updatedAt: new Date().toISOString(),
         source: "onboard",
       },
+      // The owned Docker DSN belongs only to the validated server child env.
+      // Keep normal onboarding config private but entirely free of DB secrets.
       database: {
         mode: docker ? "postgres" : "embedded-postgres",
-        ...(docker ? { connectionString: docker.connectionString } : {}),
         embeddedPostgresDataDir: path.join(instanceRoot, "db"),
         embeddedPostgresPort: databaseReservation?.port ?? 54329,
         backup: {
diff --git a/tests/runner-e2e/server.ts b/tests/runner-e2e/server.ts
index a60c3a5d6fe..adcf5e168c1 100644
--- a/tests/runner-e2e/server.ts
+++ b/tests/runner-e2e/server.ts
@@ -108,11 +108,13 @@ const serverEnvironment = buildPaperclipServerEnvironment(installedRelease
   // to Playwright in this harness, so never create a developer desktop tab.
   PAPERCLIP_OPEN_ON_LISTEN: "false",
   ...vaultEnvironment,
+  ...dockerEnvironment.serverOverrides,
 });
 assertIsolatedServerEnvironment(serverEnvironment, {
   temporaryRoot,
   paperclipHome,
   configPath,
+  ownedDatabaseUrl: dockerEnvironment.serverOverrides.DATABASE_URL,
 });
 const definedServerEnvironment = Object.fromEntries(
   Object.entries(serverEnvironment).filter(