diff --git a/packages/cli/package.json b/packages/cli/package.json
index 4fe8ef5..2039d9f 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -20,7 +20,7 @@
     "dev": "tsup --watch",
     "test": "vitest run --coverage",
     "test:watch": "vitest",
-    "lint": "eslint src --max-warnings 0",
+    "lint": "eslint src test --max-warnings 0",
     "typecheck": "tsc --noEmit && tsc --noEmit -p tsconfig.test.json",
     "clean": "rm -rf dist .turbo"
   },
diff --git a/packages/cli/test/unit/cli.test.ts b/packages/cli/test/unit/cli.test.ts
index f95e179..5bbcbf9 100644
--- a/packages/cli/test/unit/cli.test.ts
+++ b/packages/cli/test/unit/cli.test.ts
@@ -348,7 +348,7 @@ describe.skipIf(!existsSync(DIST_CLI))(
       }
       const { exitCode, stdout } = await run(
         ['--auth', '/tmp/inflow-test-no-auth.json', 'user', 'get', '--format', 'json'],
-        { env: cleanEnv as NodeJS.ProcessEnv },
+        { env: cleanEnv },
       );
       expect(exitCode).toBe(1);
       const payload = JSON.parse(stdout) as {
diff --git a/packages/cli/test/unit/commands/auth/index-tty.test.tsx b/packages/cli/test/unit/commands/auth/index-tty.test.tsx
index 8018a40..0b5c1e7 100644
--- a/packages/cli/test/unit/commands/auth/index-tty.test.tsx
+++ b/packages/cli/test/unit/commands/auth/index-tty.test.tsx
@@ -206,7 +206,7 @@ describe('runAuthLogin (tty mode)', () => {
       }),
     };
     const gen = runAuthLogin(
-      ctx as never,
+      ctx,
       {
         authResource: authStub(),
         userResource: userStub(),
@@ -248,7 +248,7 @@ describe('runAuthStatus (tty + agent details)', () => {
     };
     const storage = new MemoryStorage(sampleTokens);
     const gen = runAuthStatus(
-      ctx as never,
+      ctx,
       {
         authResource: authStub(),
         userResource: userStub(),
@@ -275,7 +275,7 @@ describe('runAuthStatus (tty + agent details)', () => {
     const storage = new MemoryStorage(sampleTokens);
     const failingUser = userStub(() => Promise.reject(new Error('network')));
     const gen = runAuthStatus(
-      ctx as never,
+      ctx,
       {
         authResource: authStub({}, storage, failingUser),
         userResource: failingUser,
@@ -359,7 +359,7 @@ describe('runAuthLogin error envelope', () => {
     await expect(
       (async () => {
         for await (const frame of runAuthLogin(
-          ctx as never,
+          ctx,
           {
             authResource: auth,
             userResource: userStub(),
@@ -394,7 +394,7 @@ describe('runAuthLogin error envelope', () => {
     await expect(
       (async () => {
         for await (const _frame of runAuthLogin(
-          ctx as never,
+          ctx,
           {
             authResource: auth,
             userResource: userStub(),
diff --git a/packages/cli/test/unit/commands/auth/login-extra.test.tsx b/packages/cli/test/unit/commands/auth/login-extra.test.tsx
index 775f9ab..756d256 100644
--- a/packages/cli/test/unit/commands/auth/login-extra.test.tsx
+++ b/packages/cli/test/unit/commands/auth/login-extra.test.tsx
@@ -56,8 +56,11 @@ describe('Login — extra branches', () => {
   });
 
   it('surfaces an authentication failure when initiateDeviceAuth rejects with a bare string', async () => {
+    // Reject with a runtime non-Error to exercise the String(error) fallback path,
+    // while typing it as Error to satisfy prefer-promise-reject-errors.
+    const bareStringFail: Error = 'bare-string-fail' as unknown as Error;
     const auth = authStub({
-      initiateDeviceAuth: vi.fn(() => Promise.reject('bare-string-fail')),
+      initiateDeviceAuth: vi.fn(() => Promise.reject(bareStringFail)),
     });
     const { lastFrame, unmount } = render(
       <Login auth={auth} clientName="Test" connection={{ environment: 'production' }} onComplete={() => undefined} />,
@@ -70,8 +73,11 @@ describe('Login — extra branches', () => {
   });
 
   it('falls back to the failed frame with a string message when polling rejects with a non-Error value', async () => {
+    // Reject with a runtime non-Error to exercise the String(error) fallback path,
+    // while typing it as Error to satisfy prefer-promise-reject-errors.
+    const bootFromServer: Error = 'boom-from-server' as unknown as Error;
     const auth = authStub({
-      pollDeviceAuth: vi.fn(() => Promise.reject('boom-from-server')),
+      pollDeviceAuth: vi.fn(() => Promise.reject(bootFromServer)),
     });
     const { lastFrame, unmount } = render(
       <Login auth={auth} clientName="Test" connection={{ environment: 'production' }} onComplete={() => undefined} />,
diff --git a/packages/cli/test/unit/commands/auth/status-extra.test.tsx b/packages/cli/test/unit/commands/auth/status-extra.test.tsx
index 3fbabe8..21e934f 100644
--- a/packages/cli/test/unit/commands/auth/status-extra.test.tsx
+++ b/packages/cli/test/unit/commands/auth/status-extra.test.tsx
@@ -217,9 +217,12 @@ describe('AuthStatus', () => {
 
   it('renders the probe-failed frame with a string fallback when probe rejects with a non-Error', async () => {
     const storage = new MemoryStorage(tokens);
+    // Reject with a runtime non-Error to exercise the String(error) fallback path,
+    // while typing it as Error to satisfy prefer-promise-reject-errors.
+    const nonErrorBoom: Error = 'boom' as unknown as Error;
     const auth = makeAuth({
       storage,
-      userImpl: () => Promise.reject('boom'),
+      userImpl: () => Promise.reject(nonErrorBoom),
     });
     const { lastFrame, unmount } = render(<AuthStatus auth={auth} probe={true} onComplete={() => undefined} />);
     await vi.waitFor(() => {
diff --git a/packages/cli/test/unit/commands/balances/index-tty.test.ts b/packages/cli/test/unit/commands/balances/index-tty.test.ts
index 4a87d30..cc37401 100644
--- a/packages/cli/test/unit/commands/balances/index-tty.test.ts
+++ b/packages/cli/test/unit/commands/balances/index-tty.test.ts
@@ -63,7 +63,7 @@ afterEach(() => {
 describe('runBalancesList (tty mode)', () => {
   it('returns the resolved balances when the TTY renderer surfaces them', async () => {
     const fixture: Balance[] = [{ available: '1.0', currency: 'USDC' }];
-    renderMock.mockImplementation(async () => fixture);
+    renderMock.mockImplementation(() => Promise.resolve(fixture));
 
     const ctx = ttyCtx();
     const storage = new MemoryStorage(tokens);
@@ -92,7 +92,7 @@ describe('runBalancesList (tty mode)', () => {
 describe('createBalancesCli', () => {
   it('returns a Cli scoped to balance commands', () => {
     const storage = new MemoryStorage(tokens);
-    const cli = createBalancesCli(balanceStub() as IBalanceResource, storage, makeInflow(storage));
+    const cli = createBalancesCli(balanceStub(), storage, makeInflow(storage));
     const description = (cli as unknown as { description?: string }).description;
     expect(description).toContain('Balance commands');
   });
diff --git a/packages/cli/test/unit/commands/inspect/inspect.test.ts b/packages/cli/test/unit/commands/inspect/inspect.test.ts
index 4a510ea..2a1562c 100644
--- a/packages/cli/test/unit/commands/inspect/inspect.test.ts
+++ b/packages/cli/test/unit/commands/inspect/inspect.test.ts
@@ -62,7 +62,7 @@ function ctx(): InspectCommandContext {
     error: (o: { code: string; message: string }) => {
       throw new Error(`${o.code}: ${o.message}`);
     },
-  } as InspectCommandContext;
+  };
 }
 
 describe('buildCombinedFrame', () => {
diff --git a/packages/cli/test/unit/commands/mpp/cancel-view.test.tsx b/packages/cli/test/unit/commands/mpp/cancel-view.test.tsx
index 98f421d..5cf8feb 100644
--- a/packages/cli/test/unit/commands/mpp/cancel-view.test.tsx
+++ b/packages/cli/test/unit/commands/mpp/cancel-view.test.tsx
@@ -7,7 +7,7 @@ describe('CancelView', () => {
   it('shows the cancelling spinner then the cancelled confirmation', async () => {
     const onComplete = vi.fn();
     const { lastFrame, unmount } = render(
-      <CancelView approvalId="ap-9" cancel={async () => undefined} onComplete={onComplete} />,
+      <CancelView approvalId="ap-9" cancel={() => Promise.resolve(undefined)} onComplete={onComplete} />,
     );
     await new Promise((r) => setTimeout(r, 50));
     expect(lastFrame() ?? '').toContain('ap-9');
diff --git a/packages/cli/test/unit/commands/mpp/index-runners.test.ts b/packages/cli/test/unit/commands/mpp/index-runners.test.ts
index bb355c0..8e69ead 100644
--- a/packages/cli/test/unit/commands/mpp/index-runners.test.ts
+++ b/packages/cli/test/unit/commands/mpp/index-runners.test.ts
@@ -34,7 +34,7 @@ function makeClient(overrides: Partial<MppClient> = {}): MppClient {
 
 function authed(
   client: MppClient,
-  cancelApproval = vi.fn(async () => undefined),
+  cancelApproval = vi.fn(() => Promise.resolve(undefined)),
 ): { inflow: Inflow; storage: AuthStorage } {
   const storage = new MemoryStorage({
     access_token: 'a',
@@ -83,7 +83,7 @@ async function drain<T>(gen: AsyncGenerator<T>): Promise<T[]> {
 
 async function drainWithReturn<T>(gen: AsyncGenerator<T, unknown>): Promise<{ values: T[]; returnValue: unknown }> {
   const values: T[] = [];
-  while (true) {
+  for (;;) {
     const next = await gen.next();
     if (next.done) return { values, returnValue: next.value };
     values.push(next.value);
@@ -99,16 +99,14 @@ describe('mpp agent runners', () => {
         { method: 'inflow', intents: [{ intent: 'charge', rails: [{ rail: 'balance', currencies: ['USDC'] }] }] },
       ],
     };
-    const { inflow, storage } = authed(
-      makeClient({ getSupported: vi.fn(async () => supported) as MppClient['getSupported'] }),
-    );
+    const { inflow, storage } = authed(makeClient({ getSupported: vi.fn(() => Promise.resolve(supported)) }));
     const ctx = { agent: true, formatExplicit: true, error: vi.fn() };
     const out = await runSupportedCommand(ctx as never, inflow, storage);
     expect(out).toEqual(supported);
   });
 
   it('runCancelCommand delegates to cancelApproval', async () => {
-    const cancelApproval = vi.fn(async () => undefined);
+    const cancelApproval = vi.fn(() => Promise.resolve(undefined));
     const { inflow, storage } = authed(makeClient(), cancelApproval);
     const ctx = { agent: true, formatExplicit: true, args: { approvalId: 'ap-1' }, error: vi.fn() };
     const out = await runCancelCommand(ctx as never, inflow, storage);
@@ -118,11 +116,13 @@ describe('mpp agent runners', () => {
 
   it('runStatusCommand (interval 0) yields a single ready snapshot', async () => {
     const client = makeClient({
-      getTransaction: vi.fn(async () => ({
-        transactionId: 'tx-1',
-        state: 'ready',
-        credential: 'CRED',
-      })) as MppClient['getTransaction'],
+      getTransaction: vi.fn(() =>
+        Promise.resolve({
+          transactionId: 'tx-1',
+          state: 'ready',
+          credential: 'CRED',
+        }),
+      ) as MppClient['getTransaction'],
     });
     const { inflow, storage } = authed(client);
     const ctx = agentCtx({ transactionId: 'tx-1' }, { interval: 0, maxAttempts: 0, timeout: 900 });
@@ -147,11 +147,13 @@ describe('mpp agent runners', () => {
     fetchSpy.mockResolvedValueOnce(challenge402());
     fetchSpy.mockResolvedValueOnce(new Response('PAID', { status: 200 }));
     const client = makeClient({
-      createTransaction: vi.fn(async () => ({
-        state: 'ready',
-        credential: 'CRED',
-        transactionId: 'tx-1',
-      })) as MppClient['createTransaction'],
+      createTransaction: vi.fn(() =>
+        Promise.resolve({
+          state: 'ready',
+          credential: 'CRED',
+          transactionId: 'tx-1',
+        }),
+      ) as MppClient['createTransaction'],
     });
     const { inflow, storage } = authed(client);
     const ctx = agentCtx(
@@ -220,11 +222,13 @@ describe('mpp agent runners', () => {
     fetchSpy.mockResolvedValueOnce(challenge402());
     fetchSpy.mockResolvedValueOnce(new Response('nope', { status: 402 }));
     const client = makeClient({
-      createTransaction: vi.fn(async () => ({
-        state: 'ready',
-        credential: 'CRED',
-        transactionId: 'tx-1',
-      })) as MppClient['createTransaction'],
+      createTransaction: vi.fn(() =>
+        Promise.resolve({
+          state: 'ready',
+          credential: 'CRED',
+          transactionId: 'tx-1',
+        }),
+      ) as MppClient['createTransaction'],
     });
     const { inflow, storage } = authed(client);
     const ctx = agentCtx(
@@ -253,17 +257,21 @@ describe('mpp agent runners', () => {
   it('runPayCommand returns the c.error sentinel when an awaited transaction expires', async () => {
     vi.spyOn(globalThis, 'fetch').mockResolvedValueOnce(challenge402());
     const client = makeClient({
-      createTransaction: vi.fn(async () => ({
-        state: 'pending',
-        transactionId: 'tx-expired',
-        approvalId: 'ap-expired',
-        approvalUrl: 'https://sandbox.inflowpay.ai/approvals/ap-expired/view/',
-        retryAfterSeconds: 1,
-      })) as MppClient['createTransaction'],
-      getTransaction: vi.fn(async () => ({
-        transactionId: 'tx-expired',
-        state: 'expired',
-      })) as MppClient['getTransaction'],
+      createTransaction: vi.fn(() =>
+        Promise.resolve({
+          state: 'pending',
+          transactionId: 'tx-expired',
+          approvalId: 'ap-expired',
+          approvalUrl: 'https://sandbox.inflowpay.ai/approvals/ap-expired/view/',
+          retryAfterSeconds: 1,
+        }),
+      ) as MppClient['createTransaction'],
+      getTransaction: vi.fn(() =>
+        Promise.resolve({
+          transactionId: 'tx-expired',
+          state: 'expired',
+        }),
+      ) as MppClient['getTransaction'],
     });
     const { inflow, storage } = authed(client);
     const ctx = agentCtxReturningError(
@@ -277,30 +285,34 @@ describe('mpp agent runners', () => {
   });
 
   it('runStatusCommand (interval > 0) errors PAYMENT_FAILED on a failed terminal', async () => {
-    const getTransaction = vi.fn(async () => ({
-      transactionId: 'tx-1',
-      state: 'failed' as const,
-      problem: {
-        type: 'https://paymentauth.org/problems/verification-failed',
-        title: 'fail',
-        status: 402,
-        detail: 'declined',
-      },
-    }));
-    const { inflow, storage } = authed(makeClient({ getTransaction: getTransaction as MppClient['getTransaction'] }));
+    const getTransaction = vi.fn(() =>
+      Promise.resolve({
+        transactionId: 'tx-1',
+        state: 'failed' as const,
+        problem: {
+          type: 'https://paymentauth.org/problems/verification-failed',
+          title: 'fail',
+          status: 402,
+          detail: 'declined',
+        },
+      }),
+    );
+    const { inflow, storage } = authed(makeClient({ getTransaction: getTransaction }));
     const ctx = agentCtx({ transactionId: 'tx-1' }, { interval: 0.01, maxAttempts: 0, timeout: 900 });
     await expect(drain(runStatusCommand(ctx as never, inflow, storage))).rejects.toThrow('c.error: PAYMENT_FAILED');
   });
 
   it('runStatusCommand (interval > 0) errors PAYMENT_EXPIRED on an expired terminal', async () => {
-    const getTransaction = vi.fn(async () => ({ transactionId: 'tx-1', state: 'expired' }));
+    const getTransaction = vi.fn(() => Promise.resolve({ transactionId: 'tx-1', state: 'expired' }));
     const { inflow, storage } = authed(makeClient({ getTransaction: getTransaction as MppClient['getTransaction'] }));
     const ctx = agentCtx({ transactionId: 'tx-1' }, { interval: 0.01, maxAttempts: 0, timeout: 900 });
     await expect(drain(runStatusCommand(ctx as never, inflow, storage))).rejects.toThrow('c.error: PAYMENT_EXPIRED');
   });
 
   it('runStatusCommand (interval > 0) errors POLLING_TIMEOUT when max attempts are exhausted', async () => {
-    const getTransaction = vi.fn(async () => ({ transactionId: 'tx-1', state: 'pending', retryAfterSeconds: 0 }));
+    const getTransaction = vi.fn(() =>
+      Promise.resolve({ transactionId: 'tx-1', state: 'pending', retryAfterSeconds: 0 }),
+    );
     const { inflow, storage } = authed(makeClient({ getTransaction: getTransaction as MppClient['getTransaction'] }));
     const ctx = agentCtx({ transactionId: 'tx-1' }, { interval: 0.01, maxAttempts: 2, timeout: 900 });
     await expect(drain(runStatusCommand(ctx as never, inflow, storage))).rejects.toThrow('c.error: POLLING_TIMEOUT');
diff --git a/packages/cli/test/unit/commands/mpp/index-tty.test.tsx b/packages/cli/test/unit/commands/mpp/index-tty.test.tsx
index 1f3de23..0c24bec 100644
--- a/packages/cli/test/unit/commands/mpp/index-tty.test.tsx
+++ b/packages/cli/test/unit/commands/mpp/index-tty.test.tsx
@@ -43,7 +43,7 @@ function authed(client: MppClient): { inflow: Inflow; storage: AuthStorage } {
   const inflow = new Inflow({ authStorage: storage, environment: 'sandbox', cliClientId: 'test' });
   (inflow.mpp as unknown as { cachedClient: Promise<MppClient> }).cachedClient = Promise.resolve(client);
   (inflow.mpp as unknown as { cachedMethod: { cancelApproval: () => Promise<void> } }).cachedMethod = {
-    cancelApproval: vi.fn(async () => undefined),
+    cancelApproval: vi.fn(() => Promise.resolve(undefined)),
   };
   return { inflow, storage };
 }
@@ -74,11 +74,13 @@ describe('mpp TTY runners (renderInkUntilExit paths)', () => {
     fetchSpy.mockResolvedValueOnce(challenge402());
     fetchSpy.mockResolvedValueOnce(new Response('PAID', { status: 200 }));
     const client = makeClient({
-      createTransaction: vi.fn(async () => ({
-        state: 'ready',
-        credential: 'CRED',
-        transactionId: 'tx-1',
-      })) as MppClient['createTransaction'],
+      createTransaction: vi.fn(() =>
+        Promise.resolve({
+          state: 'ready',
+          credential: 'CRED',
+          transactionId: 'tx-1',
+        }),
+      ) as MppClient['createTransaction'],
     });
     const { inflow, storage } = authed(client);
     const ctx = ttyCtx(
@@ -94,11 +96,13 @@ describe('mpp TTY runners (renderInkUntilExit paths)', () => {
     fetchSpy.mockResolvedValueOnce(challenge402());
     fetchSpy.mockResolvedValueOnce(new Response('nope', { status: 402 }));
     const client = makeClient({
-      createTransaction: vi.fn(async () => ({
-        state: 'ready',
-        credential: 'CRED',
-        transactionId: 'tx-1',
-      })) as MppClient['createTransaction'],
+      createTransaction: vi.fn(() =>
+        Promise.resolve({
+          state: 'ready',
+          credential: 'CRED',
+          transactionId: 'tx-1',
+        }),
+      ) as MppClient['createTransaction'],
     });
     const { inflow, storage } = authed(client);
     const ctx = ttyCtx(
@@ -124,11 +128,13 @@ describe('mpp TTY runners (renderInkUntilExit paths)', () => {
 
   it('runStatusCommand renders the status view to completion', async () => {
     const client = makeClient({
-      getTransaction: vi.fn(async () => ({
-        transactionId: 'tx-1',
-        state: 'ready',
-        credential: 'CRED',
-      })) as MppClient['getTransaction'],
+      getTransaction: vi.fn(() =>
+        Promise.resolve({
+          transactionId: 'tx-1',
+          state: 'ready',
+          credential: 'CRED',
+        }),
+      ) as MppClient['getTransaction'],
     });
     const { inflow, storage } = authed(client);
     const ctx = ttyCtx({ transactionId: 'tx-1' }, { interval: 0, maxAttempts: 0, timeout: 900 });
@@ -139,28 +145,30 @@ describe('mpp TTY runners (renderInkUntilExit paths)', () => {
   it('runCancelCommand renders the cancel view and returns the best-effort frame', async () => {
     const { inflow, storage } = authed(makeClient());
     const ctx = ttyCtx({ approvalId: 'ap-1' }, {});
-    const out = await runCancelCommand(ctx as never, inflow, storage);
+    const out = await runCancelCommand(ctx, inflow, storage);
     expect(out).toMatchObject({ approval_id: 'ap-1', cancelled: true });
   });
 
   it('runSupportedCommand renders the supported view and returns undefined', async () => {
     const client = makeClient({
-      getSupported: vi.fn(async () => ({
-        kinds: [
-          { method: 'inflow', intents: [{ intent: 'charge', rails: [{ rail: 'balance', currencies: ['USDC'] }] }] },
-        ],
-      })) as MppClient['getSupported'],
+      getSupported: vi.fn(() =>
+        Promise.resolve({
+          kinds: [
+            { method: 'inflow', intents: [{ intent: 'charge', rails: [{ rail: 'balance', currencies: ['USDC'] }] }] },
+          ],
+        }),
+      ),
     });
     const { inflow, storage } = authed(client);
     const ctx = ttyCtx({}, {});
-    const out = await runSupportedCommand(ctx as never, inflow, storage);
+    const out = await runSupportedCommand(ctx, inflow, storage);
     expect(out).toBeUndefined();
   });
 
   it('runInspectCommand renders the inspect view and returns undefined on a 2xx probe', async () => {
     vi.spyOn(globalThis, 'fetch').mockResolvedValueOnce(new Response('FREE', { status: 200 }));
     const ctx = ttyCtx({ url: SELLER }, { method: 'GET', header: [] });
-    const out = await runInspectCommand(ctx as never);
+    const out = await runInspectCommand(ctx);
     expect(out).toBeUndefined();
     expect(ctx.error).not.toHaveBeenCalled();
   });
diff --git a/packages/cli/test/unit/commands/mpp/index.test.ts b/packages/cli/test/unit/commands/mpp/index.test.ts
index 25dcd7d..84b61a4 100644
--- a/packages/cli/test/unit/commands/mpp/index.test.ts
+++ b/packages/cli/test/unit/commands/mpp/index.test.ts
@@ -3,7 +3,7 @@ import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import { encode, type MppChallenge, type MppTransactionResponse, renderChallengeHeader } from '@inflowpayai/mpp';
 import type { MppPayCreated, MppPayResultRejected, MppPayResultSuccess } from '@inflowpayai/inflow-core';
-import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { describe, expect, it } from 'vitest';
 import { __testing } from '../../../../src/commands/mpp/index.js';
 
 const {
diff --git a/packages/cli/test/unit/commands/mpp/supported-view.test.tsx b/packages/cli/test/unit/commands/mpp/supported-view.test.tsx
index 9c29c94..d111174 100644
--- a/packages/cli/test/unit/commands/mpp/supported-view.test.tsx
+++ b/packages/cli/test/unit/commands/mpp/supported-view.test.tsx
@@ -25,7 +25,9 @@ function supported(): MppSupportedResponse {
 
 describe('SupportedView', () => {
   it('renders a method/intent/rail/currencies table', async () => {
-    const { lastFrame, unmount } = render(<SupportedView load={async () => supported()} onComplete={vi.fn()} />);
+    const { lastFrame, unmount } = render(
+      <SupportedView load={() => Promise.resolve(supported())} onComplete={vi.fn()} />,
+    );
     await new Promise((r) => setTimeout(r, 50));
     const frame = lastFrame() ?? '';
     expect(frame).toContain('Method');
@@ -41,7 +43,9 @@ describe('SupportedView', () => {
     const response: MppSupportedResponse = {
       kinds: [{ method: 'inflow', intents: [{ intent: 'charge', rails: [{ rail: 'balance', currencies: [] }] }] }],
     };
-    const { lastFrame, unmount } = render(<SupportedView load={async () => response} onComplete={vi.fn()} />);
+    const { lastFrame, unmount } = render(
+      <SupportedView load={() => Promise.resolve(response)} onComplete={vi.fn()} />,
+    );
     await new Promise((r) => setTimeout(r, 50));
     const frame = lastFrame() ?? '';
     expect(frame).toContain('balance');
@@ -50,7 +54,9 @@ describe('SupportedView', () => {
   });
 
   it('renders an empty-state message when there are no kinds', async () => {
-    const { lastFrame, unmount } = render(<SupportedView load={async () => ({ kinds: [] })} onComplete={vi.fn()} />);
+    const { lastFrame, unmount } = render(
+      <SupportedView load={() => Promise.resolve({ kinds: [] })} onComplete={vi.fn()} />,
+    );
     await new Promise((r) => setTimeout(r, 50));
     expect(lastFrame() ?? '').toContain('No supported MPP methods');
     unmount();
@@ -58,12 +64,7 @@ describe('SupportedView', () => {
 
   it('shows the error message when load rejects', async () => {
     const { lastFrame, unmount } = render(
-      <SupportedView
-        load={async () => {
-          throw new Error('network down');
-        }}
-        onComplete={vi.fn()}
-      />,
+      <SupportedView load={() => Promise.reject(new Error('network down'))} onComplete={vi.fn()} />,
     );
     await new Promise((r) => setTimeout(r, 50));
     expect(lastFrame() ?? '').toContain('network down');
diff --git a/packages/cli/test/unit/commands/user/index-tty.test.ts b/packages/cli/test/unit/commands/user/index-tty.test.ts
index 65948d6..92e9e20 100644
--- a/packages/cli/test/unit/commands/user/index-tty.test.ts
+++ b/packages/cli/test/unit/commands/user/index-tty.test.ts
@@ -85,12 +85,14 @@ afterEach(() => {
 
 describe('runUserGet (tty mode)', () => {
   it('returns the user when renderInkUntilExit produces a success outcome', async () => {
-    renderMock.mockImplementation(async (_element, resolveResult) => {
+    renderMock.mockImplementation((_element, resolveResult) => {
       const resolver = resolveResult as (() => unknown) | undefined;
-      return resolver ? (resolver() ?? { kind: 'success', user: sampleUser }) : { kind: 'success', user: sampleUser };
+      return Promise.resolve(
+        resolver ? (resolver() ?? { kind: 'success', user: sampleUser }) : { kind: 'success', user: sampleUser },
+      );
     });
-    renderMock.mockImplementation(async (_element) => {
-      return { kind: 'success', user: sampleUser } as const;
+    renderMock.mockImplementation((_element) => {
+      return Promise.resolve({ kind: 'success', user: sampleUser } as const);
     });
 
     const ctx = ttyCtx();
@@ -108,7 +110,7 @@ describe('runUserGet (tty mode)', () => {
   });
 
   it('throws an IncurError when the TTY frame produced no result (null outcome)', async () => {
-    renderMock.mockImplementation(async () => null);
+    renderMock.mockImplementation(() => Promise.resolve(null));
 
     const ctx = ttyCtx();
     const storage = new MemoryStorage(tokens);
@@ -122,10 +124,12 @@ describe('runUserGet (tty mode)', () => {
   });
 
   it('throws an IncurError surfacing the error message when the TTY frame produced an error outcome', async () => {
-    renderMock.mockImplementation(async () => ({
-      kind: 'error',
-      message: 'boom',
-    }));
+    renderMock.mockImplementation(() =>
+      Promise.resolve({
+        kind: 'error',
+        message: 'boom',
+      }),
+    );
     const ctx = ttyCtx();
     const storage = new MemoryStorage(tokens);
     await expect(
diff --git a/packages/cli/test/unit/commands/x402/cancel.test.tsx b/packages/cli/test/unit/commands/x402/cancel.test.tsx
index 898bb6c..7953273 100644
--- a/packages/cli/test/unit/commands/x402/cancel.test.tsx
+++ b/packages/cli/test/unit/commands/x402/cancel.test.tsx
@@ -19,7 +19,7 @@ describe('CancelView', () => {
   it('still surfaces the confirmation when the underlying cancel rejects (fire-and-forget)', async () => {
     const onComplete = vi.fn();
     const cancel = vi.fn(() => Promise.reject(new Error('server 500')));
-    const { lastFrame, unmount } = render(<CancelView approvalId="appr_500" cancel={cancel} onComplete={onComplete} />);
+    const { unmount } = render(<CancelView approvalId="appr_500" cancel={cancel} onComplete={onComplete} />);
     await new Promise((resolve) => setTimeout(resolve, 50));
     expect(cancel).toHaveBeenCalledTimes(1);
     unmount();
diff --git a/packages/cli/test/unit/commands/x402/index-runners.test.ts b/packages/cli/test/unit/commands/x402/index-runners.test.ts
index c99954f..1758107 100644
--- a/packages/cli/test/unit/commands/x402/index-runners.test.ts
+++ b/packages/cli/test/unit/commands/x402/index-runners.test.ts
@@ -64,21 +64,25 @@ function makePrepared(
 
 function makeClient(overrides: Partial<X402InflowClient> = {}): X402InflowClient {
   const base = {
-    selectInflowRequirement: vi.fn(async () => ({
-      scheme: 'balance',
-      network: 'inflow:1',
-      amount: '500',
-      payTo: 'inflow:abc',
-      maxTimeoutSeconds: 60,
-      asset: 'USDC',
-      extra: {},
-    })),
-    prepareInflowPayment: vi.fn(async () => makePrepared()),
-    getSupported: vi.fn(async () => ({
-      kinds: [{ scheme: 'balance', network: 'inflow:1', x402Version: 2 }],
-    })),
-    getX402Payload: vi.fn(async () => ({ status: 'INITIATED' as const })),
-    cancelApproval: vi.fn(async () => undefined),
+    selectInflowRequirement: vi.fn(() =>
+      Promise.resolve({
+        scheme: 'balance',
+        network: 'inflow:1',
+        amount: '500',
+        payTo: 'inflow:abc',
+        maxTimeoutSeconds: 60,
+        asset: 'USDC',
+        extra: {},
+      }),
+    ),
+    prepareInflowPayment: vi.fn(() => Promise.resolve(makePrepared())),
+    getSupported: vi.fn(() =>
+      Promise.resolve({
+        kinds: [{ scheme: 'balance', network: 'inflow:1', x402Version: 2 }],
+      }),
+    ),
+    getX402Payload: vi.fn(() => Promise.resolve({ status: 'INITIATED' as const })),
+    cancelApproval: vi.fn(() => Promise.resolve(undefined)),
   };
   return { ...base, ...overrides } as unknown as X402InflowClient;
 }
@@ -175,7 +179,7 @@ async function drain<T>(gen: AsyncGenerator<T>): Promise<T[]> {
 
 async function drainWithReturn<T>(gen: AsyncGenerator<T, unknown>): Promise<{ values: T[]; returnValue: unknown }> {
   const values: T[] = [];
-  while (true) {
+  for (;;) {
     const next = await gen.next();
     if (next.done) return { values, returnValue: next.value };
     values.push(next.value);
@@ -305,9 +309,7 @@ describe('runPayCommand (agent mode)', () => {
       }),
     );
     const client = makeClient({
-      prepareInflowPayment: vi.fn(async () => {
-        throw new X402PaymentIdFormatError('bad-id');
-      }),
+      prepareInflowPayment: vi.fn(() => Promise.reject(new X402PaymentIdFormatError('bad-id'))),
     });
     const ctx = agentContext(
       { url: 'https://seller/api' },
@@ -333,15 +335,17 @@ describe('runPayCommand (agent mode)', () => {
         headers: { 'PAYMENT-REQUIRED': header },
       }),
     );
-    const selectSpy = vi.fn(async () => ({
-      scheme: 'balance' as const,
-      network: 'inflow:1',
-      amount: '500',
-      payTo: 'inflow:abc',
-      maxTimeoutSeconds: 60,
-      asset: 'USDC',
-      extra: {},
-    }));
+    const selectSpy = vi.fn(() =>
+      Promise.resolve({
+        scheme: 'balance' as const,
+        network: 'inflow:1',
+        amount: '500',
+        payTo: 'inflow:abc',
+        maxTimeoutSeconds: 60,
+        asset: 'USDC',
+        extra: {},
+      }),
+    );
     const client = makeClient({ selectInflowRequirement: selectSpy });
     const ctx = agentContext(
       { url: 'https://seller/api' },
@@ -393,15 +397,17 @@ describe('runPayCommand (agent mode)', () => {
         headers: { 'PAYMENT-REQUIRED': header },
       }),
     );
-    const selectSpy = vi.fn(async (_decoded: PaymentRequired) => ({
-      scheme: 'exact' as const,
-      network: 'eip155:84532',
-      amount: '500',
-      payTo: '0xabc',
-      maxTimeoutSeconds: 60,
-      asset: 'USDC',
-      extra: {},
-    }));
+    const selectSpy = vi.fn((_decoded: PaymentRequired) =>
+      Promise.resolve({
+        scheme: 'exact' as const,
+        network: 'eip155:84532',
+        amount: '500',
+        payTo: '0xabc',
+        maxTimeoutSeconds: 60,
+        asset: 'USDC',
+        extra: {},
+      }),
+    );
     const client = makeClient({ selectInflowRequirement: selectSpy });
     const ctx = agentContext(
       { url: 'https://seller/api' },
@@ -437,7 +443,7 @@ describe('runPayCommand (agent mode)', () => {
       }),
     );
     const client = makeClient({
-      selectInflowRequirement: vi.fn(async () => null),
+      selectInflowRequirement: vi.fn(() => Promise.resolve(null)),
     });
     const ctx = agentContext(
       { url: 'https://seller/api' },
@@ -464,9 +470,7 @@ describe('runPayCommand (agent mode)', () => {
       }),
     );
     const client = makeClient({
-      prepareInflowPayment: vi.fn(async () => {
-        throw new X402AdapterRoutingError('balance', 'inflow:1');
-      }),
+      prepareInflowPayment: vi.fn(() => Promise.reject(new X402AdapterRoutingError('balance', 'inflow:1'))),
     });
     const ctx = agentContext(
       { url: 'https://seller/api' },
@@ -493,7 +497,9 @@ describe('runPayCommand (agent mode)', () => {
       }),
     );
     const client = makeClient({
-      prepareInflowPayment: vi.fn(async () => makePrepared(new X402ApprovalFailedError('appr_1', 'DECLINED'))),
+      prepareInflowPayment: vi.fn(() =>
+        Promise.resolve(makePrepared(new X402ApprovalFailedError('appr_1', 'DECLINED'))),
+      ),
     });
     const ctx = agentContext(
       { url: 'https://seller/api' },
@@ -607,7 +613,7 @@ describe('runPayCommand (agent mode)', () => {
     const { inflow, storage } = authedResources(makeClient());
     await drain(runPayCommand(ctx, inflow, storage, 'https://api.inflowpay.ai'));
     const [, init] = fetchSpy.mock.calls[0] ?? [];
-    expect((init as RequestInit | undefined)?.body).toBe('{"x":1}');
+    expect(init?.body).toBe('{"x":1}');
   });
 
   it('yields replay-rejected frame and emits PAYMENT_NOT_ACCEPTED when the seller returns 402 on replay', async () => {
@@ -678,7 +684,7 @@ describe('runPayCommand (agent mode)', () => {
 describe('runStatusCommand (agent mode)', () => {
   it('yields a single status frame when interval=0 (snapshot mode)', async () => {
     const client = makeClient({
-      getX402Payload: vi.fn(async () => ({ status: 'INITIATED' })),
+      getX402Payload: vi.fn(() => Promise.resolve({ status: 'INITIATED' })),
     });
     const ctx = agentContext(
       { transactionId: 'txn_1' },
@@ -696,7 +702,7 @@ describe('runStatusCommand (agent mode)', () => {
 
   it('emits POLLING_TIMEOUT when polling exhausts max_attempts', async () => {
     const client = makeClient({
-      getX402Payload: vi.fn(async () => ({ status: 'INITIATED' })),
+      getX402Payload: vi.fn(() => Promise.resolve({ status: 'INITIATED' })),
     });
     const ctx = agentContext(
       { transactionId: 'txn_x' },
@@ -713,7 +719,7 @@ describe('runStatusCommand (agent mode)', () => {
 
   it('emits APPROVAL_FAILED when the final status is a terminal failure with no payload', async () => {
     const client = makeClient({
-      getX402Payload: vi.fn(async () => ({ status: 'DECLINED' })),
+      getX402Payload: vi.fn(() => Promise.resolve({ status: 'DECLINED' })),
     });
     const ctx = agentContext(
       { transactionId: 'txn_x' },
@@ -730,7 +736,7 @@ describe('runStatusCommand (agent mode)', () => {
 
   it('returns the c.error sentinel when the final status is a terminal failure with no payload', async () => {
     const client = makeClient({
-      getX402Payload: vi.fn(async () => ({ status: 'DECLINED' })),
+      getX402Payload: vi.fn(() => Promise.resolve({ status: 'DECLINED' })),
     });
     const ctx = agentContextReturningError(
       { transactionId: 'txn_x' },
@@ -769,7 +775,7 @@ describe('runStatusCommand (agent mode)', () => {
       },
     ];
     const client = makeClient({
-      getX402Payload: vi.fn(async () => responses.shift() ?? { status: 'INITIATED' }),
+      getX402Payload: vi.fn(() => Promise.resolve(responses.shift() ?? { status: 'INITIATED' })),
     });
     const ctx = agentContext(
       { transactionId: 'txn_x' },
@@ -788,7 +794,7 @@ describe('runStatusCommand (agent mode)', () => {
 
 describe('runCancelCommand', () => {
   it('returns the best-effort cancel envelope in agent mode', async () => {
-    const cancelApproval = vi.fn(async () => undefined);
+    const cancelApproval = vi.fn(() => Promise.resolve(undefined));
     const client = makeClient({ cancelApproval });
     const ctx = agentContextNoOptions({ approvalId: 'appr_1' });
     const { inflow, storage } = authedResources(client);
@@ -796,7 +802,7 @@ describe('runCancelCommand', () => {
     expect(result).toEqual({
       approval_id: 'appr_1',
       cancelled: true,
-      note: expect.any(String),
+      note: expect.any(String) as string,
     });
     expect(cancelApproval).toHaveBeenCalledWith('appr_1');
   });
@@ -835,7 +841,7 @@ describe('runSupportedCommand', () => {
     const ctx = agentContextNoOptions({});
     const { inflow, storage } = authedResources(makeClient());
     const result = await runSupportedCommand(ctx, inflow, storage);
-    expect(result?.kinds?.[0]?.scheme).toBe('balance');
+    expect(result?.kinds[0]?.scheme).toBe('balance');
   });
 
   it('short-circuits via c.error when not authenticated', async () => {
diff --git a/packages/cli/test/unit/commands/x402/index.test.ts b/packages/cli/test/unit/commands/x402/index.test.ts
index c9c59cf..b729c75 100644
--- a/packages/cli/test/unit/commands/x402/index.test.ts
+++ b/packages/cli/test/unit/commands/x402/index.test.ts
@@ -31,10 +31,10 @@ function preparedEvent(overrides: Record<string, unknown> = {}): Extract<PayEven
       awaitPayload: () => Promise.reject(new Error('not called in this test')),
       status: () => Promise.resolve('INITIATED' as const),
       cancel: () => Promise.resolve(),
-    } as Extract<PayEvent, { type: 'prepared' }>['prepared'],
+    },
     approvalUrl: 'https://app.inflowpay.ai/approvals/appr_1/view/',
   };
-  return { ...base, ...overrides } as Extract<PayEvent, { type: 'prepared' }>;
+  return { ...base, ...overrides };
 }
 
 describe('initialPayFrame', () => {
diff --git a/packages/cli/test/unit/commands/x402/pay-view.test.tsx b/packages/cli/test/unit/commands/x402/pay-view.test.tsx
index 269e8e0..8abca23 100644
--- a/packages/cli/test/unit/commands/x402/pay-view.test.tsx
+++ b/packages/cli/test/unit/commands/x402/pay-view.test.tsx
@@ -59,11 +59,11 @@ function prepared(
 
 function makeClient(overrides: Partial<X402InflowClient> = {}): X402InflowClient {
   const base = {
-    selectInflowRequirement: vi.fn(async () => requirement()),
-    prepareInflowPayment: vi.fn(async () => prepared()),
-    getSupported: vi.fn(async () => ({ kinds: [] })),
-    getX402Payload: vi.fn(async () => ({ status: 'INITIATED' as const })),
-    cancelApproval: vi.fn(async () => undefined),
+    selectInflowRequirement: vi.fn(() => Promise.resolve(requirement())),
+    prepareInflowPayment: vi.fn(() => Promise.resolve(prepared())),
+    getSupported: vi.fn(() => Promise.resolve({ kinds: [] })),
+    getX402Payload: vi.fn(() => Promise.resolve({ status: 'INITIATED' as const })),
+    cancelApproval: vi.fn(() => Promise.resolve(undefined)),
   };
   return { ...base, ...overrides } as unknown as X402InflowClient;
 }
@@ -149,7 +149,7 @@ describe('PayView', () => {
       }),
     );
     const client = makeClient({
-      selectInflowRequirement: vi.fn(async () => null),
+      selectInflowRequirement: vi.fn(() => Promise.resolve(null)),
     });
     const { lastFrame, unmount } = render(
       <PayView
diff --git a/packages/cli/test/unit/commands/x402/pay.test.ts b/packages/cli/test/unit/commands/x402/pay.test.ts
index 888ee36..c4fb7b7 100644
--- a/packages/cli/test/unit/commands/x402/pay.test.ts
+++ b/packages/cli/test/unit/commands/x402/pay.test.ts
@@ -115,11 +115,11 @@ function makePrepared(
 
 function makeClient(overrides: Partial<X402InflowClient> = {}): X402InflowClient {
   const base = {
-    selectInflowRequirement: vi.fn(async () => makeRequirement()),
-    prepareInflowPayment: vi.fn(async () => makePrepared()),
-    getSupported: vi.fn(async () => ({ kinds: [{ scheme: 'balance', network: 'inflow:1', x402Version: 2 }] })),
-    getX402Payload: vi.fn(async () => ({ status: 'INITIATED' })),
-    cancelApproval: vi.fn(async () => undefined),
+    selectInflowRequirement: vi.fn(() => Promise.resolve(makeRequirement())),
+    prepareInflowPayment: vi.fn(() => Promise.resolve(makePrepared())),
+    getSupported: vi.fn(() => Promise.resolve({ kinds: [{ scheme: 'balance', network: 'inflow:1', x402Version: 2 }] })),
+    getX402Payload: vi.fn(() => Promise.resolve({ status: 'INITIATED' })),
+    cancelApproval: vi.fn(() => Promise.resolve(undefined)),
   };
   return { ...base, ...overrides } as unknown as X402InflowClient;
 }
@@ -223,8 +223,8 @@ describe('runPayPipeline', () => {
       }),
     );
     const client = makeClient({
-      selectInflowRequirement: vi.fn(async () => null),
-    } as Partial<X402InflowClient>);
+      selectInflowRequirement: vi.fn(() => Promise.resolve(null)),
+    });
     const { emit, events } = captureEvents();
     await runPayPipeline(
       {
@@ -288,8 +288,10 @@ describe('runPayPipeline', () => {
       }),
     );
     const client = makeClient({
-      prepareInflowPayment: vi.fn(async () => makePrepared(new X402ApprovalFailedError('appr_1', 'DECLINED'))),
-    } as Partial<X402InflowClient>);
+      prepareInflowPayment: vi.fn(() =>
+        Promise.resolve(makePrepared(new X402ApprovalFailedError('appr_1', 'DECLINED'))),
+      ),
+    });
     const { emit, events } = captureEvents();
     await runPayPipeline(
       {
@@ -650,10 +652,10 @@ describe('runPayPipeline with --scheme / --network / --asset / --asset-name filt
       }),
     );
     fetchSpy.mockResolvedValueOnce(new Response('paid-body', { status: 200 }));
-    const selectSpy = vi.fn(async (_decoded: PaymentRequired) => makeRequirement());
+    const selectSpy = vi.fn((_decoded: PaymentRequired) => Promise.resolve(makeRequirement()));
     const client = makeClient({
       selectInflowRequirement: selectSpy,
-    } as Partial<X402InflowClient>);
+    });
     const { emit, events } = captureEvents();
     await runPayPipeline(
       {
@@ -685,10 +687,10 @@ describe('runPayPipeline with --scheme / --network / --asset / --asset-name filt
         headers: { 'PAYMENT-REQUIRED': header },
       }),
     );
-    const selectSpy = vi.fn(async (_decoded: PaymentRequired) => makeRequirement());
+    const selectSpy = vi.fn((_decoded: PaymentRequired) => Promise.resolve(makeRequirement()));
     const client = makeClient({
       selectInflowRequirement: selectSpy,
-    } as Partial<X402InflowClient>);
+    });
     const { emit, events } = captureEvents();
     await runPayPipeline(
       {
@@ -748,10 +750,10 @@ describe('runPayPipeline with --scheme / --network / --asset / --asset-name filt
         headers: { 'PAYMENT-REQUIRED': header },
       }),
     );
-    const selectSpy = vi.fn(async (_decoded: PaymentRequired) => makeRequirement());
+    const selectSpy = vi.fn((_decoded: PaymentRequired) => Promise.resolve(makeRequirement()));
     const client = makeClient({
       selectInflowRequirement: selectSpy,
-    } as Partial<X402InflowClient>);
+    });
     const { emit, events } = captureEvents();
     await runPayPipeline(
       {
@@ -786,10 +788,10 @@ describe('runPayPipeline with --scheme / --network / --asset / --asset-name filt
         headers: { 'PAYMENT-REQUIRED': header },
       }),
     );
-    const selectSpy = vi.fn(async (_decoded: PaymentRequired) => makeRequirement());
+    const selectSpy = vi.fn((_decoded: PaymentRequired) => Promise.resolve(makeRequirement()));
     const client = makeClient({
       selectInflowRequirement: selectSpy,
-    } as Partial<X402InflowClient>);
+    });
     const { emit, events } = captureEvents();
     await runPayPipeline(
       {
@@ -820,8 +822,8 @@ describe('runPayPipeline with --scheme / --network / --asset / --asset-name filt
       }),
     );
     const client = makeClient({
-      selectInflowRequirement: vi.fn(async () => null),
-    } as Partial<X402InflowClient>);
+      selectInflowRequirement: vi.fn(() => Promise.resolve(null)),
+    });
     const { emit, events } = captureEvents();
     await runPayPipeline(
       {
diff --git a/packages/cli/test/unit/commands/x402/status-view.test.tsx b/packages/cli/test/unit/commands/x402/status-view.test.tsx
index 5b1683d..77f4555 100644
--- a/packages/cli/test/unit/commands/x402/status-view.test.tsx
+++ b/packages/cli/test/unit/commands/x402/status-view.test.tsx
@@ -139,7 +139,10 @@ describe('X402StatusView', () => {
   });
 
   it('renders the error frame with a string fallback when fetchOnce throws a non-Error', async () => {
-    const fetchOnce = vi.fn(() => Promise.reject('bare-string-failure'));
+    // Reject with a runtime non-Error to exercise the String(error) fallback path,
+    // while typing it as Error to satisfy prefer-promise-reject-errors.
+    const bareStringFailure: Error = 'bare-string-failure' as unknown as Error;
+    const fetchOnce = vi.fn(() => Promise.reject(bareStringFailure));
     const { lastFrame, unmount } = render(
       <X402StatusView
         transactionId="txn_e2"
diff --git a/packages/cli/test/unit/commands/x402/supported.test.tsx b/packages/cli/test/unit/commands/x402/supported.test.tsx
index 833d3e9..812ea72 100644
--- a/packages/cli/test/unit/commands/x402/supported.test.tsx
+++ b/packages/cli/test/unit/commands/x402/supported.test.tsx
@@ -13,11 +13,13 @@ describe('SupportedView', () => {
     const onComplete = vi.fn();
     const { lastFrame, unmount } = render(
       <SupportedView
-        load={async () =>
-          makeResponse([
-            { scheme: 'balance', network: 'inflow:1', x402Version: 2 },
-            { scheme: 'exact', network: 'eip155:8453', x402Version: 2 },
-          ])
+        load={() =>
+          Promise.resolve(
+            makeResponse([
+              { scheme: 'balance', network: 'inflow:1', x402Version: 2 },
+              { scheme: 'exact', network: 'eip155:8453', x402Version: 2 },
+            ]),
+          )
         }
         onComplete={onComplete}
       />,
@@ -38,7 +40,7 @@ describe('SupportedView', () => {
   it('renders an empty-state message when kinds is []', async () => {
     const onComplete = vi.fn();
     const { lastFrame, unmount } = render(
-      <SupportedView load={async () => makeResponse([])} onComplete={onComplete} />,
+      <SupportedView load={() => Promise.resolve(makeResponse([]))} onComplete={onComplete} />,
     );
     await new Promise((resolve) => setTimeout(resolve, 50));
     expect(lastFrame() ?? '').toContain('No supported');
@@ -48,12 +50,7 @@ describe('SupportedView', () => {
   it('shows the error message when load rejects', async () => {
     const onComplete = vi.fn();
     const { lastFrame, unmount } = render(
-      <SupportedView
-        load={async () => {
-          throw new Error('server unavailable');
-        }}
-        onComplete={onComplete}
-      />,
+      <SupportedView load={() => Promise.reject(new Error('server unavailable'))} onComplete={onComplete} />,
     );
     await new Promise((resolve) => setTimeout(resolve, 50));
     expect(lastFrame() ?? '').toContain('server unavailable');
diff --git a/packages/cli/test/unit/hooks/use-flow-state.test.tsx b/packages/cli/test/unit/hooks/use-flow-state.test.tsx
index 90ad1b9..32cbb67 100644
--- a/packages/cli/test/unit/hooks/use-flow-state.test.tsx
+++ b/packages/cli/test/unit/hooks/use-flow-state.test.tsx
@@ -14,12 +14,6 @@ function Probe({ action, onComplete }: ProbeProps): React.ReactElement {
   return <Text>{`status=${status};data=${String(data)};error=${error}`}</Text>;
 }
 
-async function flushMicrotasks(rounds = 8): Promise<void> {
-  for (let i = 0; i < rounds; i++) {
-    await Promise.resolve();
-  }
-}
-
 describe('useFlowState', () => {
   it('transitions loading -> success and calls onComplete with the result', async () => {
     const onComplete = vi.fn();
diff --git a/packages/core/package.json b/packages/core/package.json
index a0b93b8..abecdbb 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -27,7 +27,7 @@
     "dev": "tsup --watch",
     "test": "vitest run --coverage",
     "test:watch": "vitest",
-    "lint": "eslint src --max-warnings 0",
+    "lint": "eslint src test --max-warnings 0",
     "typecheck": "tsc --noEmit && tsc --noEmit -p tsconfig.test.json && tsc --noEmit -p tsconfig.examples.json",
     "clean": "rm -rf dist .turbo"
   },
diff --git a/packages/core/test/unit/auth/session-presence.test.ts b/packages/core/test/unit/auth/session-presence.test.ts
index a798dae..1afea65 100644
--- a/packages/core/test/unit/auth/session-presence.test.ts
+++ b/packages/core/test/unit/auth/session-presence.test.ts
@@ -26,7 +26,7 @@ describe('hasSession', () => {
   it('short-circuits on api key: never calls storage.isAuthenticated when hasApiKey() is true', () => {
     let storageCalls = 0;
     const storage = new MemoryStorage();
-    const wrapped: typeof storage = Object.create(storage);
+    const wrapped = Object.create(storage) as typeof storage;
     wrapped.isAuthenticated = () => {
       storageCalls++;
       return false;
diff --git a/packages/core/test/unit/client.test.ts b/packages/core/test/unit/client.test.ts
index 7e9260a..fe4372c 100644
--- a/packages/core/test/unit/client.test.ts
+++ b/packages/core/test/unit/client.test.ts
@@ -1,3 +1,4 @@
+import type * as X402BuyerModule from '@inflowpayai/x402-buyer';
 import { http, HttpResponse } from 'msw';
 import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from 'vitest';
 import { Inflow, MemoryStorage } from '../../src/index.js';
@@ -5,7 +6,7 @@ import { BASE_URL, balancesHappy, userHappy } from './fixtures/handlers.js';
 import { makeServer } from './fixtures/server.js';
 
 vi.mock('@inflowpayai/x402-buyer', async (importOriginal) => {
-  const actual = await importOriginal<typeof import('@inflowpayai/x402-buyer')>();
+  const actual = await importOriginal<typeof X402BuyerModule>();
   const calls: Array<Record<string, unknown>> = [];
   return {
     ...actual,
@@ -172,7 +173,7 @@ describe('Inflow auto-wiring of device-token provider', () => {
     });
 
     server.use(
-      http.post(`${BASE_URL}/v1/oauth2/token`, async () =>
+      http.post(`${BASE_URL}/v1/oauth2/token`, () =>
         HttpResponse.json({
           access_token: 'fresh',
           refresh_token: 'r1',
diff --git a/packages/core/test/unit/flows/auth-login.test.ts b/packages/core/test/unit/flows/auth-login.test.ts
index fa79efe..c5ba7c1 100644
--- a/packages/core/test/unit/flows/auth-login.test.ts
+++ b/packages/core/test/unit/flows/auth-login.test.ts
@@ -138,7 +138,8 @@ describe('runAuthLogin', () => {
 
   it('best-effort revokes the prior refresh token after the new tokens land', async () => {
     const storage = new MemoryStorage();
-    const auth = makeAuth();
+    const revokeToken = vi.fn().mockResolvedValue(undefined);
+    const auth = makeAuth({ revokeToken });
     const run = runAuthLogin({
       authResource: auth,
       authStorage: storage,
@@ -150,7 +151,7 @@ describe('runAuthLogin', () => {
     });
     await drain(run.events);
     await vi.waitFor(() => {
-      expect(auth.revokeToken).toHaveBeenCalledWith('old-refresh');
+      expect(revokeToken).toHaveBeenCalledWith('old-refresh');
     });
   });
 
diff --git a/packages/core/test/unit/flows/auth-logout.test.ts b/packages/core/test/unit/flows/auth-logout.test.ts
index 19b628f..a4819dc 100644
--- a/packages/core/test/unit/flows/auth-logout.test.ts
+++ b/packages/core/test/unit/flows/auth-logout.test.ts
@@ -26,11 +26,12 @@ describe('runAuthLogout', () => {
     const storage = new MemoryStorage(sampleTokens);
     storage.setApiKey('inflow_old_key');
     storage.setConnection({ environment: 'sandbox' });
-    const auth = makeAuth();
+    const revokeToken = vi.fn().mockResolvedValue(undefined);
+    const auth = makeAuth({ revokeToken });
 
     await runAuthLogout({ authResource: auth, authStorage: storage });
 
-    expect(auth.revokeToken).toHaveBeenCalledWith('r');
+    expect(revokeToken).toHaveBeenCalledWith('r');
     expect(storage.getAuth()).toBeNull();
     expect(storage.getApiKey()).toBeNull();
     expect(storage.getConnection()).toBeNull();
@@ -49,11 +50,12 @@ describe('runAuthLogout', () => {
   it('skips revokeToken when no refresh_token is present in storage', async () => {
     const storage = new MemoryStorage();
     storage.setApiKey('inflow_api_key_only');
-    const auth = makeAuth();
+    const revokeToken = vi.fn().mockResolvedValue(undefined);
+    const auth = makeAuth({ revokeToken });
 
     await runAuthLogout({ authResource: auth, authStorage: storage });
 
-    expect(auth.revokeToken).not.toHaveBeenCalled();
+    expect(revokeToken).not.toHaveBeenCalled();
     expect(storage.getApiKey()).toBeNull();
   });
 });
diff --git a/packages/core/test/unit/flows/inflow-flows.test.ts b/packages/core/test/unit/flows/inflow-flows.test.ts
index 357d637..41eb302 100644
--- a/packages/core/test/unit/flows/inflow-flows.test.ts
+++ b/packages/core/test/unit/flows/inflow-flows.test.ts
@@ -1,4 +1,5 @@
 import type { MppClient } from '@inflowpayai/mpp';
+import type * as X402BuyerModule from '@inflowpayai/x402-buyer';
 import type { InflowClient as X402BuyerClient } from '@inflowpayai/x402-buyer';
 import { http, HttpResponse } from 'msw';
 import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from 'vitest';
@@ -8,16 +9,18 @@ import { BASE_URL, balancesHappy, depositAddressesHappy, userHappy } from '../fi
 import { makeServer } from '../fixtures/server.js';
 
 vi.mock('@inflowpayai/x402-buyer', async (importOriginal) => {
-  const actual = await importOriginal<typeof import('@inflowpayai/x402-buyer')>();
+  const actual = await importOriginal<typeof X402BuyerModule>();
   return {
     ...actual,
-    createInflowClient: vi.fn(async () => ({
-      getSupported: vi.fn(async () => ({ kinds: [] })),
-      selectInflowRequirement: () => null,
-      getX402Payload: vi.fn(async () => ({ status: 'INITIATED' as const })),
-      cancelApproval: vi.fn(async () => undefined),
-      prepareInflowPayment: vi.fn(),
-    })),
+    createInflowClient: vi.fn(() =>
+      Promise.resolve({
+        getSupported: vi.fn(() => Promise.resolve({ kinds: [] })),
+        selectInflowRequirement: () => null,
+        getX402Payload: vi.fn(() => Promise.resolve({ status: 'INITIATED' as const })),
+        cancelApproval: vi.fn(() => Promise.resolve(undefined)),
+        prepareInflowPayment: vi.fn(),
+      }),
+    ),
   };
 });
 
@@ -180,15 +183,20 @@ describe('augmentX402 — mutation contract', () => {
 
 function stubMppClient(overrides: Partial<MppClient> = {}): MppClient {
   return {
-    getSupported: vi.fn(async () => ({ kinds: [] })),
-    getTransaction: vi.fn(async () => ({ transactionId: 'tx-9', state: 'ready' as const, credential: 'CRED' })),
+    getSupported: vi.fn(() => Promise.resolve({ kinds: [] })),
+    getTransaction: vi.fn(() =>
+      Promise.resolve({ transactionId: 'tx-9', state: 'ready' as const, credential: 'CRED' }),
+    ),
     createTransaction: vi.fn(),
     getConfig: vi.fn(),
     ...overrides,
   } as unknown as MppClient;
 }
 
-function rawMpp(client: MppClient, cancelApproval: () => Promise<void> = vi.fn(async () => undefined)): IMppResource {
+function rawMpp(
+  client: MppClient,
+  cancelApproval: () => Promise<void> = vi.fn(() => Promise.resolve(undefined)),
+): IMppResource {
   return { client: () => Promise.resolve(client), cancelApproval };
 }
 
@@ -228,13 +236,13 @@ describe('Inflow.mpp augmented operations', () => {
         { method: 'inflow', intents: [{ intent: 'charge', rails: [{ rail: 'balance', currencies: ['USDC'] }] }] },
       ],
     };
-    const raw = rawMpp(stubMppClient({ getSupported: vi.fn(async () => supported) as MppClient['getSupported'] }));
+    const raw = rawMpp(stubMppClient({ getSupported: vi.fn(() => Promise.resolve(supported)) }));
     const mpp = augmentMpp(raw, 'https://api.example.test');
     await expect(mpp.supported()).resolves.toEqual(supported);
   });
 
   it('mpp.cancel delegates to cancelApproval and returns the best-effort frame', async () => {
-    const cancelApproval = vi.fn(async () => undefined);
+    const cancelApproval = vi.fn(() => Promise.resolve(undefined));
     const mpp = augmentMpp(rawMpp(stubMppClient(), cancelApproval), 'https://api.example.test');
     await expect(mpp.cancel({ approvalId: 'ap-7' })).resolves.toEqual({
       approval_id: 'ap-7',
@@ -282,7 +290,7 @@ describe('wrapEmittingPipeline — error propagation through the MPP pay handle'
   it('rethrows an Error raised before the pipeline starts', async () => {
     const raw: IMppResource = {
       client: () => Promise.reject(new Error('client boom')),
-      cancelApproval: vi.fn(async () => undefined),
+      cancelApproval: vi.fn(() => Promise.resolve(undefined)),
     };
     const mpp = augmentMpp(raw, 'https://api.example.test');
     const run = mpp.pay({
@@ -297,9 +305,12 @@ describe('wrapEmittingPipeline — error propagation through the MPP pay handle'
   });
 
   it('wraps a non-Error rejection in an InflowSdkError carrying its string form', async () => {
+    // The pipeline is expected to wrap non-Error rejections; cast preserves the
+    // runtime string value while satisfying prefer-promise-reject-errors.
+    const nonErrorReason = 'weird-failure' as unknown as Error;
     const raw: IMppResource = {
-      client: () => Promise.reject('weird-failure'),
-      cancelApproval: vi.fn(async () => undefined),
+      client: () => Promise.reject(nonErrorReason),
+      cancelApproval: vi.fn(() => Promise.resolve(undefined)),
     };
     const mpp = augmentMpp(raw, 'https://api.example.test');
     const run = mpp.pay({
diff --git a/packages/core/test/unit/flows/mpp-inspect.test.ts b/packages/core/test/unit/flows/mpp-inspect.test.ts
index 8a8eb93..c1fe9e3 100644
--- a/packages/core/test/unit/flows/mpp-inspect.test.ts
+++ b/packages/core/test/unit/flows/mpp-inspect.test.ts
@@ -118,7 +118,7 @@ describe('runMppInspectPipeline', () => {
   it('errors INVALID_402 when the 402 carries no WWW-Authenticate header', async () => {
     server.use(http.get(SELLER, () => new HttpResponse(null, { status: 402 })));
     const [event] = await collect();
-    expect(event).toEqual({ type: 'errored', code: 'INVALID_402', message: expect.any(String) });
+    expect(event).toEqual({ type: 'errored', code: 'INVALID_402', message: expect.any(String) as string });
   });
 
   it('errors NO_INFLOW_MATCH when the 402 carries only unsupported method challenges', async () => {
diff --git a/packages/core/test/unit/flows/mpp-shared.test.ts b/packages/core/test/unit/flows/mpp-shared.test.ts
index 02adbca..02b4a8a 100644
--- a/packages/core/test/unit/flows/mpp-shared.test.ts
+++ b/packages/core/test/unit/flows/mpp-shared.test.ts
@@ -29,7 +29,7 @@ function decodableChallenge(over: {
       currency: over.currency ?? 'USDC',
       methodDetails: { rail: over.rail ?? 'balance' },
     }),
-  } as unknown as MppChallenge;
+  };
 }
 
 const usdcBalance = decodableChallenge({ id: 'a', currency: 'USDC', rail: 'balance' });
diff --git a/packages/core/test/unit/flows/x402-status.test.ts b/packages/core/test/unit/flows/x402-status.test.ts
index 7b64171..51a7876 100644
--- a/packages/core/test/unit/flows/x402-status.test.ts
+++ b/packages/core/test/unit/flows/x402-status.test.ts
@@ -26,13 +26,13 @@ describe('classifyPayloadResponse', () => {
 
   it('classifies terminal failure statuses as failed', () => {
     for (const status of TERMINAL_FAILURE_STATUSES) {
-      expect(classifyPayloadResponse({ status } as unknown as X402PayloadResponse)).toBe('failed');
+      expect(classifyPayloadResponse({ status })).toBe('failed');
     }
   });
 
   it('classifies everything else as pending', () => {
-    expect(classifyPayloadResponse({ status: 'INITIATED' } as unknown as X402PayloadResponse)).toBe('pending');
-    expect(classifyPayloadResponse({ status: 'AWAITING_SIGNATURE' } as unknown as X402PayloadResponse)).toBe('pending');
+    expect(classifyPayloadResponse({ status: 'INITIATED' })).toBe('pending');
+    expect(classifyPayloadResponse({ status: 'AWAITING_SIGNATURE' })).toBe('pending');
   });
 });