fix(ios): native host terminal server and PTY reconnect

[bajrangCoder]

Why

On iOS the terminal was unstable: it broke after backgrounding, started slowly and sometimes failed to connect. The Android design had been ported as is. On Android, AXS runs natively under proot. On iOS it ran inside the Linux emulator, so every keystroke went through emulated sockets, epoll, tokio threads and an emulated PTY. The emulator's socket restart hooks were also never called. iOS reclaims listening sockets of suspended apps, so AXS kept running while its port was dead, and isAxsRunning still returned true.

What changed

Each platform has its own native implementation behind the same API. JS and plugin APIs (Terminal, Executor, and the AXS HTTP/WebSocket protocol on 127.0.0.1:8767) are unchanged.

Android:  xterm.js ──▶ AXS (native in proot) ──▶ bash                          (unchanged)
iOS:      xterm.js ──▶ TerminalServer (Swift) ──▶ guest /dev/pts ──▶ bash (only bash is emulated)

iOS terminal

• Bridge/AlpineTerminal.c: a tty driver registered through the emulator's pty_open_fake (the approach iSH uses). Guest output goes straight to Swift. Input, resize and hangup go straight to the guest tty. Bash still gets job control, termios and SIGWINCH.
• TerminalServer / TerminalSession (Swift): implement the AXS routes (/terminals, /resize, /terminate, /status, /execute-command, WebSocket).
  • Output is batched like AXS (8 ms / 8 KB).
  • The last 256 KB of output is replayed when a client reattaches.
  • A program writing faster than the client reads is paused instead of growing memory.
• LocalWebSocket: a minimal RFC 6455 server layer on top of the existing LocalHTTPServer / LocalHTTPConnection (new upgrade()).
• The emulator's socket restart hooks (sockrestart) now run on suspend/resume, and the terminal listener restarts when the app returns to the foreground.
• init-alpine.sh --prepare runs once per boot; each terminal then starts bash --rcfile /initrc -i directly. The axs binary stays in the guest for users and plugins.

Shared / Android

• init-alpine.sh:
  • one apk info -e call instead of four on every start;
  • new --prepare flag;
  • the bash DEBUG-trap binary check (two subshells per command) now only runs where /sdcard or /storage exists.
• terminal.js: on an unexpected socket drop, the terminal reattaches to the same PTY with backoff (0 / 0.5 / 1.5 / 3 s) instead of closing the tab. The tab only closes when the session is really gone.
  • Behaviour change: a socket error after connecting no longer shows the error alert immediately; the close handler decides whether to retry.

Other fixes

• LocalHTTPServer: loopback listeners on a fixed port failed with EINVAL, because the port was passed both to on: and inside requiredLocalEndpoint. This also broke EmbeddedProxyServer.
• spawnStream (language servers):
  • output goes straight from the pipe to the socket on its own queue, instead of through AlpineRuntime.queue;
  • stopped stream servers are removed instead of piling up.

Testing

On the iOS simulator (iPhone 17 Pro), all four Alpine suites pass when run together:

• AlpineTerminalTests, extended to check:
  • resize reaches the PTY (stty size → 40 100);
  • output is replayed after reattaching;
  • the exit frame is sent;
  • terminate works.
• AlpineInteractionTests, extended to drop a live tab's socket and check that it reattaches to the same shell (the exported variable is still set).
• AlpineLspTests and AlpinePackageTests.
• PreviewServerTests also pass.

Not yet verified:

• Physical iPhone: memory limits, backgrounding, performance.

🤖 Generated with Claude Code