fix(agents): fold non-Latin scripts + close echo-verify test holes

Echo fold kept only ASCII a-z/0-9, so a prompt in Cyrillic/CJK/Arabic/etc.
folded to nothing, hit the unmatchable branch, and fired echo on any render
— a blind submit onto a swallow screen for non-English users, the same
#7466 failure. Fold on the Unicode letter/number classes instead; box
borders and punctuation still drop, so Latin folding is unchanged.

Also strengthen two vacuous FIX-2 guards proven by a revert experiment:
the snapshot-exclusion assertion matched only the first callback arg (the
watcher receives a second meta arg, so not.toHaveBeenCalledWith never
matched), and the echo watch's includeSnapshot:false wiring was unasserted.
Both now fail when the fix is reverted.

Co-authored-by: Orca <help@stably.ai>

src/renderer/src/lib/prompt-echo-wait.test.ts

@@ -107,6 +107,15 @@ describe('watchForPromptEcho', () => {
       )
       const watch = watchForPromptEcho('remote-pty', PROMPT, 10_000, {})
       await flushMicrotasks()
+      // The echo watch must opt out of the pre-paste buffer snapshot (#7466),
+      // or a swallow screen already on the terminal could falsely verify.
+      expect(mocks.subscribeToRuntimeTerminalData).toHaveBeenCalledWith(
+        expect.anything(),
+        'remote-pty',
+        expect.any(String),
+        expect.any(Function),
+        { includeSnapshot: false }
+      )
       remoteObserver?.(ECHO)
       await expect(watch.result).resolves.toBe(true)
       expect(remoteUnsubscribe).toHaveBeenCalledTimes(1)

src/renderer/src/runtime/runtime-terminal-stream.test.ts

@@ -189,8 +189,10 @@ describe('remote runtime terminal data subscriptions', () => {
     // Live output rendered after the subscription still reaches the watcher.
     deliverOutput(streamId, 'live')
 
-    expect(watcher).not.toHaveBeenCalledWith('PRE-PASTE SCREEN')
-    expect(watcher).toHaveBeenCalledWith('live')
+    // onSnapshot passes a second meta arg, so match on the first arg only —
+    // a bare not.toHaveBeenCalledWith(...) would vacuously pass either way.
+    expect(watcher.mock.calls.map((call) => call[0])).not.toContain('PRE-PASTE SCREEN')
+    expect(watcher.mock.calls.map((call) => call[0])).toContain('live')
   })
 
   it('keeps the shared terminal multiplexer until the last watcher closes', async () => {

src/shared/prompt-echo-scanner.test.ts

@@ -103,4 +103,13 @@ describe('createPromptEchoScanner', () => {
     const scanner = createPromptEchoScanner('fix ci')
     expect(scanner.observe('\x1b[11;3Hfix\x1b[11;7Hci')).toBe(true)
   })
+
+  it('verifies a non-Latin-script prompt instead of failing open on any render', () => {
+    // #7466: Cyrillic folds to letters (not away), so it matches on its render
+    // and correctly withholds the submit on a swallow screen.
+    const swallowed = createPromptEchoScanner('Разреши конфликты слияния')
+    expect(swallowed.observe(CODEX_TRUST_SWALLOW_REDRAW)).toBe(false)
+    const rendered = createPromptEchoScanner('Разреши конфликты слияния')
+    expect(rendered.observe('\x1b[11;3HРазреши\x1b[11;15Hконфликты\x1b[11;25Hслияния')).toBe(true)
+  })
 })

src/shared/prompt-echo-scanner.ts

@@ -7,9 +7,12 @@
 /**
  * Fold terminal output down to comparable text:
  *   - strip OSC (title/hyperlink) and CSI/charset escape sequences
- *   - drop every non-alphanumeric character (TUIs repaint with cursor moves
- *     instead of literal spaces, wrap lines at pane width, and draw box
- *     borders through the text, so only the letters/digits survive intact)
+ *   - drop every non-letter/non-number character (TUIs repaint with cursor
+ *     moves instead of literal spaces, wrap lines at pane width, and draw box
+ *     borders through the text, so only the letters/digits survive intact).
+ *     Uses the Unicode letter/number classes rather than ASCII so non-Latin
+ *     prompts (Cyrillic, CJK, Arabic, ...) still fold to matchable content
+ *     instead of vanishing to nothing.
  *   - lowercase for case-stable matching
  */
 export function foldTerminalTextForEchoMatch(raw: string): string {
@@ -23,16 +26,7 @@ export function foldTerminalTextForEchoMatch(raw: string): string {
     .replace(/\x1b[()#][0-9A-Za-z]/g, '')
     .replace(/\x1b[@-_]/g, '')
   /* oxlint-enable no-control-regex */
-  let folded = ''
-  for (const ch of withoutEscapes.toLowerCase()) {
-    const code = ch.codePointAt(0) ?? 0
-    const isDigit = code >= 48 && code <= 57
-    const isLower = code >= 97 && code <= 122
-    if (isDigit || isLower) {
-      folded += ch
-    }
-  }
-  return folded
+  return withoutEscapes.toLowerCase().replace(/[^\p{L}\p{N}]/gu, '')
 }
 
 // Why: large pastes never render verbatim — codex collapses to