fix(terminal): address review: Key tester isolates shortcuts, Codex stays on line feed

- app.js: the shortcut dispatcher returns early for events aimed at a data-raw-keys
  field, so Ctrl+W / Ctrl+L / Escape / Alt+1 / Ctrl+K pressed in the Key tester no
  longer kill the session, clear the terminal or close Settings
- stock.ts: drop Codex's esc-enter (a line feed works); no stock CLI declares a chord.
  The esc-enter path is tested through a clis.json override
- tests: unused port (3194), Ctrl+Enter asserts no keypress, shortcut-isolation test
  (verified to fail without the guard)
- docs/comments point at capabilities.newline; set-input class, trailing whitespace

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.changeset/newline-capability-key-tester.md

@@ -2,4 +2,4 @@
 "aicodeman": patch
 ---
 
-Shift+Enter's newline chord is now registry data (`capabilities.newline`: `line-feed` by default, `esc-enter` for Codex) instead of being chosen in the `send-key` route, so a CLI with a different composer is one line in `stock.ts`. Adds a Key tester under Settings → Terminal & Input that shows the keydown/keypress/keyup events a browser reports, to diagnose a device where a shortcut behaves differently.
+Shift+Enter's newline chord is now registry data (`capabilities.newline`: `line-feed` by default, `esc-enter` available for a CLI whose composer ignores a bare line feed; no stock CLI changes) instead of being chosen in the `send-key` route. Adds a Key tester under Settings → Terminal & Input that shows the keydown/keypress/keyup events a browser reports, to diagnose a device where a shortcut behaves differently. Keys pressed in the tester no longer trigger app shortcuts (Ctrl+W, Ctrl+L, Escape, ...).

docs/architecture-invariants.md

@@ -191,7 +191,7 @@ Further detail (current geometry and colors, superseding the dip numbers above w
 
 **Three owners, one setter.** `SessionState.nameSource` is `placeholder` | `auto` | `manual`. The constructor infers a missing value from the name (`isGeneratedSessionName()` = `w<n>-<case>` / `s<n>-<case>`, or no name at all, is a placeholder; anything else was a person's), the create routes pass none, the boot restore passes the persisted one. The `name` setter is the manual path and the ONLY thing that produces `manual` after construction; `applyAutoName()` is the only thing that produces `auto`, and it does so whether or not the string changed, which is what makes "first prompt" mean the first. A prompt whose title is null (`/clear`, `! npm test`, blank) never reaches it, so the session stays eligible: the first REAL prompt names the tab.
 
-**The origin gate defaults to "system".** `write()` / `writeViaMux()` take `SessionWriteOptions.fromUser`; only the browser WS path and `POST /api/sessions/:id/input` set it. Every other caller (Ralph, respawn, cron, approvals, the orchestrator's `/compact`, auto-ops, the trust-dialog keys) is system by omission, so a new user-input path that forgets the flag fails toward a tab that keeps its placeholder, never toward a tab named after a Ralph prompt. `_lastSubmitAt` is still stamped for every write; only the tracker feed is gated. The shell gate is `getCli(mode)?.capabilities.startMode !== 'shell'`, a capability rather than an id check (the no-id-branching guard), and the send-key route feeds `trackUserInput()` by hand because its `tmux send-keys -H` line feed never passes through the session.
+**The origin gate defaults to "system".** `write()` / `writeViaMux()` take `SessionWriteOptions.fromUser`; only the browser WS path and `POST /api/sessions/:id/input` set it. Every other caller (Ralph, respawn, cron, approvals, the orchestrator's `/compact`, auto-ops, the trust-dialog keys) is system by omission, so a new user-input path that forgets the flag fails toward a tab that keeps its placeholder, never toward a tab named after a Ralph prompt. `_lastSubmitAt` is still stamped for every write; only the tracker feed is gated. The shell gate is `getCli(mode)?.capabilities.startMode !== 'shell'`, a capability rather than an id check (the no-id-branching guard), and the send-key route feeds `trackUserInput()` by hand because its `tmux send-keys -H` newline (a line feed unless the CLI declares another `capabilities.newline` chord) never passes through the session.
 
 **The tracker is a best-effort transcript with explicit per-key rules**, not a byte filter. Mirrored: printable text, backspace, Ctrl+W, Ctrl+U/Ctrl+C (composer emptied), `\n` and Alt+Enter (a newline IN the composer, joined with a space), bracketed paste (newlines inside it likewise). Ignored: cursor keys, Home/End/Delete, Shift+Tab, Tab, SGR mouse and focus reports, Alt chords, OSC/DCS, the rest of C0. Tainting: Up/Down (CSI and SS3), Ctrl+P/N/R, Ctrl+_, because the composer then holds a history line the tracker never saw and Enter must submit nothing rather than a fragment. A bare Esc is resolved at the END of the chunk it arrives in, since xterm hands each key's whole sequence to one write and the programmatic senders send Esc alone; a CSI split across chunks still resumes. The draft keeps its HEAD past 8192 code points (the title is the first sentence, so keeping the tail would title a long paste by its last line) and an escape sequence is abandoned past 64 bytes.
 
@@ -780,7 +780,7 @@ Further detail: with many sessions the horizontal strip stops being scannable, w
 
 ### Split-pane sessions
 
-**Split-pane sessions** (`showSplitButton`, header button, default OFF, per-device like `showFileViewerButton` — not in `SettingsUpdateSchema`, `displayKeys` in settings-ui.js): shows two live sessions side-by-side in one Codeman window. Pane A is the untouched, existing singleton terminal (`this.terminal`/`this._ws` in terminal-ui.js); Pane B is a new, independent `SplitTerminalPane` (terminal-split.js) with its own xterm instance and its own `/ws/sessions/:id/terminal` WebSocket. ⚠️ **Pane B is deliberately plainer than Pane A** — no local-echo overlay, no CJK IME, no touch/mobile handlers, no keyboard accessory bar — since this is a desktop-only feature (a split view needs a wide viewport) and those features exist for mobile/touch input; `.btn-split` is hard-hidden below 1180px regardless of the setting by the `@media (max-width: 1179px)` rule in styles.css (mobile.css only carries a comment pointing at it: that file loads up to 1023px, so it cannot cover the 1024-1179px tablet range the feature also needs to stay off), and the per-device setting means turning it on at a desk can never sync it onto a phone in the first place. No persistence: closing the browser tab or reloading always returns to the normal single-pane view; there is no localStorage key for split state. ⚠️ Splitting a session against itself is disallowed (the picker excludes the active session), **as is splitting against a popped-out (detached) session** — `buildSplitPickerSessions()` excludes `detachedSessions` because a detached session's own window is already claiming its PTY size, and `MAX_WS_PER_SESSION` needs no change since Pane A/B are always two different sessions. ⚠️ Either pane's session ending (deleted locally or from another client) auto-collapses the split — Pane A's session ending promotes Pane B to the new single pane via `selectSession(id, { auto: true })` (an app-driven selection, so it must not spend the session's idle alert — see the Approvals Inbox note above), never by trying to hot-swap the lightweight `SplitTerminalPane` object into the primary singleton state. ⚠️ Pane B refits on every window/sidebar/tab-rail resize via the SAME trailing-edge `ResizeObserver` callback that resizes Pane A (`throttledResize` in terminal-ui.js) — it only ever measured Pane A's own container, so without an explicit `this._splitPane?.fit()` call there Pane B silently kept its stale PTY size through every resize that did not happen to be a divider drag. ⚠️ A dropped WebSocket leaves Pane B visibly dead (a message written into its own xterm buffer) rather than silently swallowing keystrokes with nothing on screen to explain why — there is no reconnect logic for v1, matching the "deliberately plainer than Pane A" design. Related but distinct: `detachSession()` already opens one session in a separate OS-level browser window (`isSoloWindow`) — that is prior art for "two sessions visible at once" but not for one window with a draggable in-page divider, which is what this feature adds. ⚠️ Pane B installs its own `attachCustomKeyEventHandler` gating the same app-level chords Pane A's own handler gates (command palette, Alt+1-9/[/] tab nav, Alt+B sidebar toggle, Ctrl+Z suspend, Shift/Ctrl+Enter newline, smart-copy Ctrl+C) — without it the document capture-phase handler's `preventDefault()` (which never stops xterm) let each chord ALSO write its raw byte/escape sequence into Pane B's live PTY on top of whatever the app action did to Pane A (COD-153). Ctrl+Z is swallowed unless Pane B's own session is `mode === 'shell'`, mirroring terminal-ui.js's reasoning: in a plain shell it is the user's own job-control tool, everywhere else it silently suspends an unattended agent loop. Shift/Ctrl+Enter POSTs to `/api/sessions/:id/send-key` (`{key:'S-Enter'|'C-Enter'}`, tmux `send-keys -H` for a real 0x0a) targeting THIS pane's own `sessionId` rather than the primary pane's `activeSessionId` — without it xterm's plain `\r` would submit an incomplete prompt instead of adding a line to it. Smart-copy Ctrl+C/Ctrl+Shift+C is re-implemented against `this.terminal` (Pane B's own) rather than reusing `app.copyTerminalSelection()`, which reads Pane A's terminal and would copy the wrong pane's selection; Ctrl+Shift+C never falls through even with nothing to copy, mirroring terminal-ui.js's own `ev.shiftKey` branch. ⚠️ **This is a UX-parity fix, not an interrupt-safety one** — verified live in a real browser: xterm's `evaluateKeyboardEvent` routes a shifted ctrl-letter into a branch that assigns `c.key` only for two special cases (`_`→US, `@`→NUL), so it emits no data for Ctrl+Shift+C at all regardless of any application gate; a synthetic keydown with the gate removed produces zero WS frames, proving no accidental interrupt reaches the PTY either way. What gating the whole copy block on `hasSelection()` (an earlier draft) actually cost: with no selection, a selection-less Ctrl+Shift+C fell straight to `return trLine truncated
+**Split-pane sessions** (`showSplitButton`, header button, default OFF, per-device like `showFileViewerButton` — not in `SettingsUpdateSchema`, `displayKeys` in settings-ui.js): shows two live sessions side-by-side in one Codeman window. Pane A is the untouched, existing singleton terminal (`this.terminal`/`this._ws` in terminal-ui.js); Pane B is a new, independent `SplitTerminalPane` (terminal-split.js) with its own xterm instance and its own `/ws/sessions/:id/terminal` WebSocket. ⚠️ **Pane B is deliberately plainer than Pane A** — no local-echo overlay, no CJK IME, no touch/mobile handlers, no keyboard accessory bar — since this is a desktop-only feature (a split view needs a wide viewport) and those features exist for mobile/touch input; `.btn-split` is hard-hidden below 1180px regardless of the setting by the `@media (max-width: 1179px)` rule in styles.css (mobile.css only carries a comment pointing at it: that file loads up to 1023px, so it cannot cover the 1024-1179px tablet range the feature also needs to stay off), and the per-device setting means turning it on at a desk can never sync it onto a phone in the first place. No persistence: closing the browser tab or reloading always returns to the normal single-pane view; there is no localStorage key for split state. ⚠️ Splitting a session against itself is disallowed (the picker excludes the active session), **as is splitting against a popped-out (detached) session** — `buildSplitPickerSessions()` excludes `detachedSessions` because a detached session's own window is already claiming its PTY size, and `MAX_WS_PER_SESSION` needs no change since Pane A/B are always two different sessions. ⚠️ Either pane's session ending (deleted locally or from another client) auto-collapses the split — Pane A's session ending promotes Pane B to the new single pane via `selectSession(id, { auto: true })` (an app-driven selection, so it must not spend the session's idle alert — see the Approvals Inbox note above), never by trying to hot-swap the lightweight `SplitTerminalPane` object into the primary singleton state. ⚠️ Pane B refits on every window/sidebar/tab-rail resize via the SAME trailing-edge `ResizeObserver` callback that resizes Pane A (`throttledResize` in terminal-ui.js) — it only ever measured Pane A's own container, so without an explicit `this._splitPane?.fit()` call there Pane B silently kept its stale PTY size through every resize that did not happen to be a divider drag. ⚠️ A dropped WebSocket leaves Pane B visibly dead (a message written into its own xterm buffer) rather than silently swallowing keystrokes with nothing on screen to explain why — there is no reconnect logic for v1, matching the "deliberately plainer than Pane A" design. Related but distinct: `detachSession()` already opens one session in a separate OS-level browser window (`isSoloWindow`) — that is prior art for "two sessions visible at once" but not for one window with a draggable in-page divider, which is what this feature adds. ⚠️ Pane B installs its own `attachCustomKeyEventHandler` gating the same app-level chords Pane A's own handler gates (command palette, Alt+1-9/[/] tab nav, Alt+B sidebar toggle, Ctrl+Z suspend, Shift/Ctrl+Enter newline, smart-copy Ctrl+C) — without it the document capture-phase handler's `preventDefault()` (which never stops xterm) let each chord ALSO write its raw byte/escape sequence into Pane B's live PTY on top of whatever the app action did to Pane A (COD-153). Ctrl+Z is swallowed unless Pane B's own session is `mode === 'shell'`, mirroring terminal-ui.js's reasoning: in a plain shell it is the user's own job-control tool, everywhere else it silently suspends an unattended agent loop. Shift/Ctrl+Enter POSTs to `/api/sessions/:id/send-key` (`{key:'S-Enter'|'C-Enter'}`, tmux `send-keys -H` for a real 0x0a, or the CLI's declared `capabilities.newline` chord) targeting THIS pane's own `sessionId` rather than the primary pane's `activeSessionId` — without it xterm's plain `\r` would submit an incomplete prompt instead of adding a line to it. Smart-copy Ctrl+C/Ctrl+Shift+C is re-implemented against `this.terminal` (Pane B's own) rather than reusing `app.copyTerminalSelection()`, which reads Pane A's terminal and would copy the wrong pane's selection; Ctrl+Shift+C never falls through even with nothing to copy, mirroring terminal-ui.js's own `ev.shiftKey` branch. ⚠️ **This is a UX-parity fix, not an interrupt-safety one** — verified live in a real browser: xterm's `evaluateKeyboardEvent` routes a shifted ctrl-letter into a branch that assigns `c.key` only for two special cases (`_`→US, `@`→NUL), so it emits no data for Ctrl+Shift+C at all regardless of any application gate; a synthetic keydown with the gate removed produces zero WS frames, proving no accidental interrupt reaches the PTY either way. What gating the whole copy block on `hasSelection()` (an earlier draft) actually cost: with no selection, a selLine truncated
 
 ### Gesture control: the setting
 

docs/cli-registry.md

@@ -120,7 +120,7 @@ sure its row is one the agent cannot write.
 
 ## The newline chord
 
-`capabilities.newline` (`'line-feed'` | `'esc-enter'`, absent = line feed) is the byte sequence the `send-key` route types into the pane for Shift+Enter. A line feed (`0x0a`, also Ctrl+Enter) is what Claude Code's Ink input reads as "insert a newline"; `esc-enter` (`ESC CR`, the Option/Alt+Enter chord) is for a composer that ignores a bare line feed, which Codex does in some terminals (#495). It is an enum rather than a byte string on purpose: config never carries bytes that get typed into a pane. Settings → Terminal & Input → **Key tester** prints what a browser reports for keydown/keypress/keyup, to see whether a device is sending what you think.
+`capabilities.newline` (`'line-feed'` | `'esc-enter'`, absent = line feed) is the byte sequence the `send-key` route types into the pane for Shift+Enter. A line feed (`0x0a`, also Ctrl+Enter) is what Claude Code's Ink input reads as "insert a newline"; `esc-enter` (`ESC CR`, the Option/Alt+Enter chord) is there for a composer that ignores a bare line feed. No stock CLI declares it today: the bytes are typed by tmux on the server, so the browser's OS cannot change what a CLI reads, and Codex 0.147.0 was checked to take a line feed (a Shift+Enter that submits is the keypress leak fixed in #520, not a byte problem). A user `clis.json` can set it for a CLI that needs it. It is an enum rather than a byte string on purpose: config never carries bytes that get typed into a pane. Settings → Terminal & Input → **Key tester** prints what a browser reports for keydown/keypress/keyup, to see whether a device is sending what you think.
 
 ## Arg-template safety
 

src/config/cli-registry/stock.ts

@@ -620,9 +620,6 @@ const CODEX: CliEntry = {
     // `dangerouslyBypassApprovals` on the wire), so it is the one that would have caught a
     // regression; `schema.ts` now rejects a name that is not a declared param.
     privilegedParams: [{ param: 'bypassApprovals', clampTo: false }],
-    // Codex's composer ignores a bare line feed in some terminals (Windows browsers, #495); the
-    // Esc+Enter chord is the one its own Option+Enter uses.
-    newline: 'esc-enter',
     // Verified by hand against a real llama.cpp server. Written to an isolated CODEX_HOME
     // so the user's real ~/.codex/config.toml is never touched.
     customModelInjection: {

src/web/public/app.js

@@ -1242,6 +1242,12 @@ class CodemanApp {
 
     // Use capture to handle before terminal
     document.addEventListener('keydown', (e) => {
+      // A field that exists to show what a key does (Settings → Key tester, `data-raw-keys`) must
+      // receive every chord untouched. Without this, probing Ctrl+W killed the active session,
+      // Ctrl+L cleared the terminal and Escape closed Settings: this listener runs in the capture
+      // phase, before the field's own handler. Must stay the first statement.
+      if (e.target?.closest?.('[data-raw-keys]')) return;
+
       // Don't intercept keys during CJK IME composition
       if (e.isComposing || e.keyCode === 229) return;
 

src/web/public/index.html

@@ -1822,7 +1822,7 @@
                   </div>
                 </div>
               </div>
-            
+
               <div class="set-group">
                 <div class="set-group-head"><h4>Key tester</h4><span class="set-scope">device</span></div>
                 <div class="set-group-body">
@@ -1831,7 +1831,7 @@
                       <span class="set-row-label">Key tester</span>
                       <span class="set-row-desc">Click the box and press keys to see what this browser reports (key, code, modifiers) for keydown, keypress and keyup. Useful when a shortcut such as Shift+Enter behaves differently on one device. Nothing is sent to a session.</span>
                     </div>
-                    <input type="text" id="keyTesterInput" class="set-select" readonly autocomplete="off" spellcheck="false"
+                    <input type="text" id="keyTesterInput" class="set-input" data-raw-keys readonly autocomplete="off" spellcheck="false"
                       placeholder="Click here, then press keys"
                       onkeydown="app.keyTesterEvent(event)" onkeypress="app.keyTesterEvent(event)" onkeyup="app.keyTesterEvent(event)">
                   </div>

src/web/routes/session-routes.ts

@@ -2093,8 +2093,9 @@ export function registerSessionRoutes(
 
   // ========== Send Named Key (tmux send-keys -H) ==========
   // Sends raw hex bytes to tmux pane for keys like Shift+Enter / Ctrl+Enter.
-  // Uses send-keys -H (hex) to inject 0x0a (line feed) which Claude Code's
+  // Uses send-keys -H (hex) to inject a newline chord: 0x0a (line feed) by default, or the CLI's
-  // Ink input recognizes as "insert newline" vs 0x0d (carriage return = submit).
+  // own `capabilities.newline`. Claude Code's Ink input recognizes 0x0a as "insert newline" vs
+  // 0x0d (carriage return = submit).
 
   app.post('/api/sessions/:id/send-key', async (req) => {
     const { id } = req.params as { id: string };

test/cli-newline-capability.test.ts

@@ -10,11 +10,11 @@ import type { CliEntry } from '../src/config/cli-registry/types.js';
 const claude = () => structuredClone(STOCK_CLIS.find((e) => (e.id as string) === 'claude')!) as CliEntry;
 
 describe('capabilities.newline', () => {
-  it('only codex declares a non-default chord today', () => {
+  it('no stock CLI declares a chord: every one keeps the line feed', () => {
-    const declared = Object.fromEntries(
+    // codex 0.147.0 takes a line feed (checked against a real tmux pane), so there is no CLI that
-      STOCK_CLIS.filter((e) => e.capabilities.newline).map((e) => [e.id as string, e.capabilities.newline])
+    // needs esc-enter yet. The capability exists for a user clis.json override and the next CLI.
-    );
+    const declared = STOCK_CLIS.filter((e) => e.capabilities.newline).map((e) => e.id as string);
-    expect(declared).toEqual({ codex: 'esc-enter' });
+    expect(declared).toEqual([]);
   });
 
   it.each(['line-feed', 'esc-enter'])('schema accepts %s', (value) => {

test/key-tester.browser.test.ts

@@ -3,7 +3,7 @@ import { describe, it, expect, beforeAll, afterAll } from 'vitest';
 import { chromium, type Browser, type Page } from 'playwright';
 import { WebServer } from '../src/web/server.js';
 
-const PORT = 3197;
+const PORT = 3194;
 
 describe('Key tester in a real browser', () => {
   let server: WebServer;
@@ -43,6 +43,49 @@ describe('Key tester in a real browser', () => {
     const text = await log();
     expect(text).toMatch(/keydown\s+key="Enter" code=Enter mods=ctrl/);
     expect(text).toMatch(/keyup/);
+    // Chromium emits no keypress for a Ctrl chord, which is why only Shift+Enter ever leaked a \r.
+    expect(text).not.toMatch(/keypress/);
+  });
+
+  it('lets no app shortcut fire for keys pressed in the field (Ctrl+W, Ctrl+L, Escape, Alt+1, Ctrl+K)', async () => {
+    // The shortcut dispatcher is a capture-phase document listener, so without a guard it ran before
+    // the field's own handler: Ctrl+W killed the active session, Ctrl+L cleared the terminal and
+    // Escape closed Settings, while this row says nothing is sent to a session.
+    await page.evaluate(() => {
+      const app = (window as any).app;
+      const calls: string[] = [];
+      (window as any).__calls = calls;
+      for (const name of ['killActiveSession', 'clearTerminal', 'openCommandPalette', 'closeAllPanels']) {
+        app[name] = (...args: unknown[]) => void calls.push(name + args.length);
+      }
+    });
+    await page.focus('#keyTesterInput');
+    // [chord, what the tester must report for it]; checked one at a time because the log keeps 14 lines.
+    const chords: [string, RegExp][] = [
+      ['Control+W', /key="w" code=KeyW mods=ctrl/i],
+      ['Control+L', /key="l" code=KeyL mods=ctrl/i],
+      ['Escape', /key="Escape" code=Escape/],
+      ['Alt+1', /code=Digit1 mods=alt/],
+      ['Control+K', /key="k" code=KeyK mods=ctrl/i],
+    ];
+    for (const [chord, seen] of chords) {
+      await page.evaluate(() => (document.getElementById('keyTesterLog')!.textContent = ''));
+      await page.keyboard.press(chord);
+      expect(await log(), chord).toMatch(seen);
+      expect(await page.evaluate(() => (window as any).__calls), chord).toEqual([]);
+    }
+    expect(await page.evaluate(() => document.getElementById('appSettingsModal')!.classList.contains('active'))).toBe(
+      true
+    );
+  });
+
+  it('still lets the shortcut fire anywhere else (the guard is scoped to data-raw-keys)', async () => {
+    await page.evaluate(() => {
+      (window as any).__calls.length = 0;
+      (document.activeElement as HTMLElement | null)?.blur();
+    });
+    await page.keyboard.press('Escape');
+    expect(await page.evaluate(() => (window as any).__calls)).toContain('closeAllPanels0');
   });
 
   it('keeps only the last 14 lines and never types into the field', async () => {

test/routes/session-routes.test.ts

@@ -17,7 +17,9 @@ import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
 import Fastify, { type FastifyInstance } from 'fastify';
 import fastifyCookie from '@fastify/cookie';
 import fastifyMultipart from '@fastify/multipart';
-import { join } from 'node:path';
+import { dirname, join } from 'node:path';
+import { mkdirSync, rmSync, writeFileSync } from 'node:fs';
+import { registryFilePath, reloadCliRegistry } from '../../src/config/cli-registry/registry.js';
 import { mkdtemp, rm, mkdir, writeFile } from 'node:fs/promises';
 import { tmpdir } from 'node:os';
 import { createMockRouteContext, type MockRouteContext } from '../mocks/index.js';
@@ -193,8 +195,34 @@ describe('session-routes', () => {
         expect(await sentHex('opencode', 'S-Enter')).toEqual(['0a']);
       });
 
-      it('sends Esc+Enter for Shift+Enter to a CLI that declares esc-enter', async () => {
+      it('sends a line feed to Codex too: no stock CLI declares a chord', async () => {
-        expect(await sentHex('codex', 'S-Enter')).toEqual(['1b', '0d']);
+        expect(await sentHex('codex', 'S-Enter')).toEqual(['0a']);
+      });
+
+      describe('a CLI that declares esc-enter (here via a user clis.json override of codex)', () => {
+        beforeEach(() => {
+          const file = registryFilePath();
+          mkdirSync(dirname(file), { recursive: true });
+          writeFileSync(
+            file,
+            JSON.stringify({ schemaVersion: 1, clis: { codex: { capabilities: { newline: 'esc-enter' } } } }),
+            { mode: 0o600 }
+          );
+          reloadCliRegistry();
+        });
+        afterEach(() => {
+          rmSync(registryFilePath(), { force: true });
+          reloadCliRegistry();
+        });
+
+        it('sends Esc+Enter for Shift+Enter, and only to that CLI', async () => {
+          expect(await sentHex('codex', 'S-Enter')).toEqual(['1b', '0d']);
+          expect(await sentHex('claude', 'S-Enter')).toEqual(['0a']);
+        });
+
+        it('still sends a line feed for Ctrl+Enter', async () => {
+          expect(await sentHex('codex', 'C-Enter')).toEqual(['0a']);
+        });
       });
 
       it('always sends a line feed for Ctrl+Enter', async () => {