Terminal PTY Selection

Provenance — Migrated 2026-10-06 from docs/implementation/terminal-pty-selection.md @ zuohaisu/viva@871a00a · 迁移自主仓库该文件；正文相对链接已改为 Wiki 链接，原始状态/日期/作者行保留，原文以 Git 历史为准。

V05 Terminal / PTY Reuse Selection

Status: Delivered with V05 (issue #14) · 2026-09-28 · Lane E

Issue #14's 2026-09-28 supplement requires a recorded reuse check against the Orca fixed-source audit before choosing a PTY approach. This document is that record.

Checked capabilities

• Orca TerminalHost / PTY slice (docs/research/orca-reuse-audit-2026-09-28.md): the audit found no plain-Node orcad build entry without Electron, and the TerminalHost slice is not published as an independent library — extracting it means carrying Orca's runner/cache/WSL coupling. Reuse would also import Orca's detach/disconnect-then-keep-running semantics, which Viva must not keep (owned terminals stop with the Viva host).
• portable-pty 0.9.0 (wezterm's pty layer, maintained, MIT): owns the pty/session discipline (setsid + controlling terminal on Unix), giving each session a real process group without hand-rolled tty ioctls.
• vt100 0.16.2 (MIT): parses raw output into a bounded grid + ring scrollback; byte-exact ANSI fidelity is preserved separately in the disk log, so nothing fakes the transcript.

Decision

Use portable-pty (session/process-group discipline) + vt100 (grid emulation). Viva's own terminal::session owns lifecycle: SIGTERM → timeout → SIGKILL to the process group with reap confirmation, bounded memory, and byte-level redacted disk logs. No Orca code, binary, CLI, or private metadata is used; no Orca.app dependency exists.

Licenses (transitive set of the new dependencies)

Crate	Version	License
portable-pty	0.9.0	MIT
vt100	0.16.2	MIT
ratatui	0.30.2	MIT
crossterm	0.29.0	MIT
libc	0.2.189	MIT OR Apache-2.0

Pending (not claimed here)

• Intel Mac acceptance stays with V12; this lane validated on macOS arm64 and Linux CI runs the same suite.
• Real Pi composition (V09) and 16-Agent soak (V12) are separate gates.