diff --git a/web/playwright.config.ts b/web/playwright.config.ts
new file mode 100644
index 0000000..7a4516b
--- /dev/null
+++ b/web/playwright.config.ts
@@ -0,0 +1,21 @@
+import { defineConfig, devices } from '@playwright/test';
+
+export default defineConfig({
+  testDir: './tests/e2e',
+  fullyParallel: false,
+  retries: 0,
+  workers: 1,
+  reporter: [['list']],
+  use: {
+    headless: true,
+    actionTimeout: 15_000,
+    navigationTimeout: 30_000,
+    ignoreHTTPSErrors: true,
+  },
+  projects: [
+    {
+      name: 'chromium',
+      use: { ...devices['Desktop Chrome'] },
+    },
+  ],
+});
diff --git a/web/src/App.tsx b/web/src/App.tsx
index c3142f9..47106ea 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -11,6 +11,7 @@ import { useApprovalsQueue } from '@/state/useApprovalsQueue';
 import { useAgentDefinitions } from '@/state/useAgentDefinitions';
 import { useSessionFull } from '@/state/useSessionFull';
 import { MonitorRail } from '@/monitors/MonitorRail';
+import { NewSessionModal } from '@/modals/NewSessionModal';
 
 const UI_VERSION = 'v2.0.0-rc1';
 const RUNTIME_VERSION_FALLBACK = 'unknown';
@@ -32,6 +33,7 @@ const paneStyle: CSSProperties = {
 
 export function App() {
   const [activeSid, setActiveSid] = useState<string | null>(null);
+  const [newSessionOpen, setNewSessionOpen] = useState(false);
 
   const uiHints = useUiHints();
   const sessionList = useSessionList();
@@ -65,7 +67,7 @@ export function App() {
         health={health}
         approvalsCount={approvals.count}
         onSearch={() => {/* Phase 6: open search overlay */}}
-        onNew={() => {/* Phase 6: open NewSessionModal */}}
+        onNew={() => setNewSessionOpen(true)}
         onApprovalsClick={() => {/* Phase 6: open approvals view */}}
       />
       <FlowStrip
@@ -98,6 +100,12 @@ export function App() {
         runtimeVersion={RUNTIME_VERSION_FALLBACK}
         uiVersion={UI_VERSION}
       />
+      <NewSessionModal
+        open={newSessionOpen}
+        onOpenChange={setNewSessionOpen}
+        environments={uiHints.data?.environments ?? ['dev']}
+        onCreated={(sid) => setActiveSid(sid)}
+      />
     </div>
   );
 }
diff --git a/web/src/modals/NewSessionModal.tsx b/web/src/modals/NewSessionModal.tsx
new file mode 100644
index 0000000..f6b4feb
--- /dev/null
+++ b/web/src/modals/NewSessionModal.tsx
@@ -0,0 +1,153 @@
+import { useState, useEffect } from 'react';
+import type { CSSProperties } from 'react';
+import { Modal } from '@/components/Modal';
+import { apiFetch, ApiClientError } from '@/api/client';
+
+interface NewSessionModalProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  environments: string[];
+  onCreated: (sid: string) => void;
+}
+
+interface StartResponse {
+  session_id: string;
+}
+
+const labelStyle: CSSProperties = {
+  display: 'block',
+  fontFamily: 'var(--ff-mono)',
+  fontSize: 10,
+  color: 'var(--ink-3)',
+  letterSpacing: '0.14em',
+  textTransform: 'uppercase',
+  marginBottom: 4,
+};
+
+const fieldWrap: CSSProperties = { marginBottom: 16 };
+
+const inputStyle: CSSProperties = {
+  width: '100%',
+  height: 32,
+  padding: '0 10px',
+  fontFamily: 'var(--ff-sans)',
+  fontSize: 13,
+  color: 'var(--ink-1)',
+  background: 'var(--bg-elev)',
+  border: '1px solid var(--hair)',
+  borderRadius: 0,
+  outline: 'none',
+  boxSizing: 'border-box',
+};
+
+const textareaStyle: CSSProperties = {
+  ...inputStyle,
+  height: 'auto',
+  minHeight: 96,
+  padding: '8px 10px',
+  resize: 'vertical',
+  fontFamily: 'var(--ff-sans)',
+  lineHeight: 1.5,
+};
+
+const selectStyle: CSSProperties = {
+  ...inputStyle,
+  height: 32,
+  appearance: 'auto',
+};
+
+export function NewSessionModal({ open, onOpenChange, environments, onCreated }: NewSessionModalProps) {
+  const [query, setQuery] = useState('');
+  const [environment, setEnvironment] = useState(environments[0] ?? 'dev');
+  const [submitting, setSubmitting] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  useEffect(() => {
+    if (!open) {
+      setQuery('');
+      setError(null);
+      setSubmitting(false);
+      setEnvironment(environments[0] ?? 'dev');
+    }
+  }, [open, environments]);
+
+  const canSubmit = query.trim().length > 0 && !submitting;
+
+  async function handleSubmit() {
+    if (!canSubmit) return;
+    setSubmitting(true);
+    setError(null);
+    try {
+      const res = await apiFetch<StartResponse>('/sessions', {
+        method: 'POST',
+        json: { query: query.trim(), environment, submitter: { id: 'operator' } },
+      });
+      onCreated(res.session_id);
+      onOpenChange(false);
+    } catch (e) {
+      if (e instanceof ApiClientError) {
+        setError(`${e.code}: ${e.message}`);
+      } else {
+        setError(String(e));
+      }
+      setSubmitting(false);
+    }
+  }
+
+  return (
+    <Modal
+      open={open}
+      onOpenChange={onOpenChange}
+      eyebrow="NEW SESSION"
+      title="Start a new session"
+      primaryAction={{
+        label: submitting ? 'Starting…' : 'Create session',
+        onClick: () => { void handleSubmit(); },
+        disabled: !canSubmit,
+      }}
+    >
+      <div style={fieldWrap}>
+        <label style={labelStyle} htmlFor="ns-query">Query</label>
+        <textarea
+          id="ns-query"
+          autoFocus
+          placeholder="Describe the incident or task in plain language…"
+          value={query}
+          onChange={(e) => setQuery(e.target.value)}
+          style={textareaStyle}
+          disabled={submitting}
+        />
+      </div>
+      <div style={fieldWrap}>
+        <label style={labelStyle} htmlFor="ns-env">Environment</label>
+        <select
+          id="ns-env"
+          value={environment}
+          onChange={(e) => setEnvironment(e.target.value)}
+          style={selectStyle}
+          disabled={submitting}
+        >
+          {environments.map((env) => (
+            <option key={env} value={env}>{env}</option>
+          ))}
+        </select>
+      </div>
+      {error && (
+        <div
+          role="alert"
+          style={{
+            marginTop: 12,
+            padding: '8px 10px',
+            fontFamily: 'var(--ff-mono)',
+            fontSize: 11,
+            color: 'var(--danger)',
+            background: 'var(--danger-bg)',
+            border: '1px solid var(--danger)',
+          }}
+        >
+          {error}
+        </div>
+      )}
+    </Modal>
+  );
+}
diff --git a/web/tests/e2e/new-session.live.spec.ts b/web/tests/e2e/new-session.live.spec.ts
new file mode 100644
index 0000000..3987f33
--- /dev/null
+++ b/web/tests/e2e/new-session.live.spec.ts
@@ -0,0 +1,41 @@
+import { test, expect } from '@playwright/test';
+
+const BASE = process.env.E2E_BASE_URL ?? 'https://clm.randomcodespace.dev';
+
+test('shell renders + New Session creates a INC- id and opens canvas', async ({ page }) => {
+  test.setTimeout(60_000);
+
+  page.on('console', (msg) => {
+    if (msg.type() === 'error') console.log('[browser-err]', msg.text());
+  });
+  page.on('pageerror', (err) => console.log('[page-err]', err.message));
+
+  await page.goto(BASE);
+
+  // Shell renders
+  await expect(page.getByText(/Sessions/i).first()).toBeVisible();
+  await expect(page.getByText(/All Systems Normal|Degraded|Critical/i)).toBeVisible();
+  await expect(page.getByText(/Select a session/i)).toBeVisible();
+
+  // Open the modal
+  await page.getByRole('button', { name: /New Session/i }).click();
+  await expect(page.getByText(/Start a new session/i)).toBeVisible();
+
+  // Fill + submit
+  const query = `e2e smoke ${Date.now()}: high p99 on payments-svc`;
+  await page.locator('#ns-query').fill(query);
+  await page.getByRole('button', { name: /Create session/i }).click();
+
+  // Modal closes
+  await expect(page.getByText(/Start a new session/i)).toBeHidden({ timeout: 30_000 });
+
+  // Canvas shows the new session id (backend uses INC-YYYYMMDD-NNN form)
+  const sidLocator = page.getByText(/INC-\d{4,}/).first();
+  await expect(sidLocator).toBeVisible({ timeout: 30_000 });
+  const sid = (await sidLocator.textContent()) ?? '';
+  expect(sid).toMatch(/INC-\d{4,}/);
+
+  // Canvas head renders meta row (env + turns counters)
+  await expect(page.getByText(/ENV /)).toBeVisible();
+  await expect(page.getByText(/TURNS /)).toBeVisible();
+});