fix(terminal): drop native ARGV0 for bun-pty via env -u

bun-pty merges the OS environ into PTY children, so deleting ARGV0 from the
JS env object alone left the AppImage path in the shell. Wrap Linux PTY
spawns with env -u ARGV0, clear native ARGV0 under Bun via libc unsetenv,
and always clear process.env even when no login-shell snapshot exists.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/web/server/lib/terminal/DOCUMENTATION.md

@@ -24,7 +24,7 @@ HTTP remains the authenticated command plane for create, resize, appearance upda
 - Concurrent creates for one ID are single-flight only when working directory and shell preference match. Existing IDs cannot be reused for another working directory.
 - Dimensions are bounded to 1-1000 columns and 1-500 rows; input is capped at 64 KiB.
 - PTY children explicitly clear `NODE_CHANNEL_FD`; daemon IPC descriptors are host-private and invalid after PTY descriptor cleanup.
-- PTY children also strip AppImage `ARGV0` (and other host-private shell vars such as `ELECTRON_RUN_AS_NODE`, `BASH_ENV`, `ENV`, `BASH_XTRACEFD`). An exported `ARGV0` makes zsh rewrite argv[0] for every external command, which breaks Python venv detection and other argv[0]/$0 consumers while leaving `/proc/self/exe` correct.
+- PTY children also strip AppImage `ARGV0` (and other host-private shell vars such as `ELECTRON_RUN_AS_NODE`, `BASH_ENV`, `ENV`, `BASH_XTRACEFD`). An exported `ARGV0` makes zsh rewrite argv[0] for every external command, which breaks Python venv detection and other argv[0]/$0 consumers while leaving `/proc/self/exe` correct. On Linux, PTY spawn is wrapped with `env -u ARGV0` because `bun-pty` merges the native OS environ and would otherwise reintroduce `ARGV0` after a JS-only delete.
 - `GET /api/terminal/shells` reports shell IDs available on the active server using the same augmented PATH provided to spawned PTYs, plus whether each executable has a supported login-mode argument. `auto` preserves environment/platform fallback order; an explicit unavailable shell fails creation instead of silently running a different shell. Login mode is opt-in and uses only built-in arguments for known shells. Preference changes affect new sessions and explicit restarts, not running PTYs.
 - PTY data and exit callbacks enter one FIFO queue. Stale callbacks from replaced processes are ignored.
 - Scrollback is retained on the server and capped at 512 KiB with UTF-8-safe trimming. Device-status, device-attribute, cursor-position reply, and color-query exchanges are removed from replay history with incomplete control sequences carried across PTY chunks; live output remains byte-for-byte unchanged.

packages/web/server/lib/terminal/runtime.js

@@ -10,7 +10,7 @@ import {
 import { sanitizeTerminalHistoryChunk } from './history.js';
 import { consumeTerminalThemeQueries, terminalThemeModeReport } from './theme-response.js';
 import { createTerminalShellResolver, getTerminalShellLoginArgs, normalizeTerminalShell } from './shells.js';
-import { stripAppImageArgv0Leak } from '../inherited-env.js';
+import { stripAppImageArgv0Leak, resolveLinuxPtyLaunch } from '../inherited-env.js';
 
 const MAX_SESSIONS = 20;
 const MAX_HISTORY_BYTES = 512 * 1024;
@@ -68,9 +68,11 @@ export function createTerminalRuntime({
         env.NODE_CHANNEL_FD = '';
         delete env.BASH_XTRACEFD; delete env.BASH_ENV; delete env.ENV; delete env.ELECTRON_RUN_AS_NODE;
         // AppImage exports ARGV0; zsh would otherwise rewrite argv[0] for every command (#2588).
+        // bun-pty also merges the native OS environ, so wrap with `env -u ARGV0` on Linux.
         stripAppImageArgv0Leak(env);
+        const launch = resolveLinuxPtyLaunch(executable, args);
         const options = { name: 'xterm-256color', cwd, cols, rows, env, ...(process.platform === 'win32' ? { useConpty: true } : {}) };
-        return { process: provider.spawn(executable, args, options), backend: provider.backend, shell: resolvedShell.id, loginShell };
+        return { process: provider.spawn(launch.executable, launch.args, options), backend: provider.backend, shell: resolvedShell.id, loginShell };
       } catch (error) { lastError = error; }
     }
     throw lastError ?? new Error('No executable shell found');

packages/web/server/lib/terminal/runtime.test.js

@@ -156,6 +156,10 @@ describe('terminal runtime', () => {
       expect(harness.processes[0].options.env.NODE_CHANNEL_FD).toBe('');
       expect(harness.processes[0].options.env).not.toHaveProperty('ARGV0');
       expect(harness.processes[0].options.env).not.toHaveProperty('ELECTRON_RUN_AS_NODE');
+      if (process.platform === 'linux') {
+        expect(harness.processes[0].shell).toMatch(/\/env$/);
+        expect(harness.processes[0].args.slice(0, 3)).toEqual(['-u', 'ARGV0', expect.any(String)]);
+      }
       harness.processes[0].emitData('\u001b[?2031h\u001b]10;?\u0007\u001b]11;?\u0007');
       expect(harness.processes[0].writes).toEqual(['\u001b]10;rgb:1b1b/1b1b/1b1b\u001b\\', '\u001b]11;rgb:fafa/f8f8/f0f0\u001b\\']);
 
@@ -184,6 +188,11 @@ describe('terminal runtime', () => {
       await harness.routes.post.get('/api/terminal/create')({ body: { sessionId: 'term-argv0', cwd: '/repo', cols: 80, rows: 24 } }, response);
       expect(response.statusCode).toBe(200);
       expect(harness.processes[0].options.env).not.toHaveProperty('ARGV0');
+      if (process.platform === 'linux') {
+        expect(harness.processes[0].shell).toMatch(/\/env$/);
+        expect(harness.processes[0].args[0]).toBe('-u');
+        expect(harness.processes[0].args[1]).toBe('ARGV0');
+      }
     } finally {
       if (previousArgv0 === undefined) delete process.env.ARGV0;
       else process.env.ARGV0 = previousArgv0;
@@ -216,14 +225,24 @@ describe('terminal runtime', () => {
       const created = createResponse();
       await harness.routes.post.get('/api/terminal/create')({ body: { sessionId: 'term-shell', cwd: '/repo', shell: 'zsh', loginShell: true } }, created);
       expect(created.statusCode).toBe(200);
-      expect(harness.processes[0].shell).toBe('/bin/zsh');
-      expect(harness.processes[0].args).toEqual(['-l']);
+      if (process.platform === 'linux') {
+        expect(harness.processes[0].shell).toMatch(/\/env$/);
+        expect(harness.processes[0].args).toEqual(['-u', 'ARGV0', '/bin/zsh', '-l']);
+      } else {
+        expect(harness.processes[0].shell).toBe('/bin/zsh');
+        expect(harness.processes[0].args).toEqual(['-l']);
+      }
 
       const restarted = createResponse();
       await harness.routes.post.get('/api/terminal/:sessionId/restart')({ params: { sessionId: 'term-shell' }, body: { shell: 'bash', loginShell: true } }, restarted);
       expect(restarted.statusCode).toBe(200);
-      expect(harness.processes[1].shell).toBe('/bin/bash');
-      expect(harness.processes[1].args).toEqual(['-l']);
+      if (process.platform === 'linux') {
+        expect(harness.processes[1].shell).toMatch(/\/env$/);
+        expect(harness.processes[1].args).toEqual(['-u', 'ARGV0', '/bin/bash', '-l']);
+      } else {
+        expect(harness.processes[1].shell).toBe('/bin/bash');
+        expect(harness.processes[1].args).toEqual(['-l']);
+      }
     } finally { await harness.runtime.shutdown(); }
   });