TUI paints empty frames on macOS ARM64 (Apple Silicon): server boots fully but renderer never draws UI — 1.16.2, 1.17.0, 1.18.21

Environment

• OS: macOS 26.x (Darwin 25.6.0), Apple M5 Max (ARM64)
• Terminals tested: WezTerm (current), Herdr multiplexer panes, raw PTY with synthetic query responses
• Versions tested: 1.16.2, 1.17.0, 1.18.21 (official install script)
• Reproduces with: --pure, no plugins, no project config, no global config, autoupdate: false

Summary

On this machine no version of the OpenCode TUI ever renders UI. Two failure stages, both observed:

1. Config-dependent boot stall: with the default config present, the process hangs after loading config files — log ends at the last loading path=... line, no error. Moving all configs/plugins aside lets boot complete.
2. Renderer paints nothing regardless: even when the backend boots fully (init → created session → event connected in logs) and the terminal answers every capability query, the screen shows only blank rows.

opencode run "..." also produces no output on stdin/stdout, same machine.

Evidence

Log progression with clean config (v1.17.0, WezTerm, real terminal):

init
created id=ses_fd27ff7a2ffelh8mjND5h6TyHQ slug=misty-sailor version=1.17.0 ... directory=/Users/davidandrews/PycharmProjects/lex
event connected

→ Window remained blank. User confirmed no TUI ever visible.

Raw PTY capture (no responder): process emits exactly the capability query block and then goes silent for minutes:

\x1b[>0q \x1bP+q4d73 \x1b[?1016$p \x1b[?2027$p \x1b[?2031$p \x1b[?1004$p \x1b[?2004$p \x1b[?2026$p \x1b]10;? \x1b]11;? \x1b]99;i=opentui-notifications:p=?; \x1b]1337;Capabilities \x1b]66;w=1;

284 bytes total (1.18.21), 274 bytes (1.16.2). Matches #32361 byte-for-byte.

Raw PTY capture (all queries answered: XTVERSION, XTGETTCAP, DECRQM ;2$y, OSC 10/11 color replies, DSR [6n): handshake completes, process then emits ~6.5 KB of cursor-positioning + full-width space rows — it actively paints empty frames and continues painting empty frames for 45+ s. Zero UI glyphs (OpenCode, Ask anything, BUILD never appear in the byte stream).

sample of hung process: ~100% of main-thread samples in kevent64 (event loop waiting, not spinning). JavaScriptCore worker threads present.

Ruled out:

• Project/global config content (repro with all configs moved away)
• Plugins (--pure, plugin dirs emptied — including a third-party integration shim in ~/.config/opencode/plugins/)
• MCP servers (project config with 9 MCP servers removed)
• Terminal emulator (3 different environments incl. raw PTY where we answer everything ourselves)
• Autoupdate (OPENCODE_DISABLE_AUTOUPDATE=1, "autoupdate": false)
• Stale state (~/.cache/opencode, ~/.local/share/opencode, ~/.opencode cleared)
• Version regression window from #32361 — pinned 1.16.2/1.17.0, still fails here

Notable observation

The one render path that DID paint visible UI on this machine is opencode --mini (banner + input prompt rendered once in a multiplexer pane), though keyboard input did not attach there either.

Related

• #32361 (blank hang since v1.17.0, Ubuntu + macOS ARM64 reports)
• #41284 (blank freeze at startup, macOS Apple Silicon)
• #35494 (Debian blank freeze)
• #37803 ("render loop silently stalls")
• #24475 (tmux hang, waitForThemeMode blocking)

Happy to run any instrumented build, capture more traces, or test patches.