Phase 3: PTY support + mix e2b.terminal interactive terminal - #1

Summary

Adds pseudo-terminal (PTY) support to E2bEx, reaching feature parity with the JS/Python SDKs' pty namespace. This is Phase 3 of the Commands parity roadmap (Phases 1 & 2 — streaming + background execution — already landed).

• E2bEx.Pty — create/3 (launches an interactive /bin/bash -i -l on a PTY of :cols×:rows), connect/4 (reconnect by pid), and by-pid send_input/5 / resize/5 / kill/4.
• E2bEx.Pty.Handle — pid/1, send_input/2, resize/2, kill/1, wait/1, disconnect/1. Distinct struct exposing only PTY-valid ops; backed by the same Commands.HandleServer.
• Message-first model: output is the merged {ref, {:pty, bytes}} channel (not stdout/stderr), ending with a terminal {:exit, %CommandResult{}} / {:error, %Error{}}. wait/1 returns an exit-code-only %CommandResult{} (PTY output is not buffered).

Internals

• Commands.Fold gains an emit-only pty data-event branch (decodes data.pty, emits {:pty, _}, accumulates nothing).
• Envd.Rpc gains send_pty_input/3 (the pty input channel) and resize/3 (the Update RPC).
• Commands.HandleServer is reused unchanged — PTY just hands it a different request map.

Notable decisions

• No Pty.list — neither SDK has one; listing stays on Commands.
• create/3 raises ArgumentError on missing :cols/:rows (a programmer error, like Client.new without :api_key).
• PTY is background-only (no blocking run analog, matching the SDKs).
• The two previously-flagged refactors (shared receive_timeout constant; collapsing streaming-request construction into Rpc) are intentionally deferred to keep this diff PTY-only.

Spec: docs/superpowers/specs/2026-06-11-e2b-pty-design.md · Plan: docs/superpowers/plans/2026-06-11-e2b-pty.md

Test Plan

• mix test — 142 tests, 0 failures
• mix compile --warnings-as-errors — clean
• Wire shapes (Start pty.size, Update resize, SendInput input.pty, data.pty decode) verified against the envd proto and JS SDK
• Coverage: Fold pty branch + invalid base64; Rpc send_pty_input/resize (+ non-2xx error); Pty.create/connect streaming; by-pid controls; Handle.wait (drain, crash) / disconnect; pre-start context error

🤖 Generated with Claude Code

Added: mix e2b.terminal (interactive terminal)

This PR now also includes a raw interactive terminal built on the PTY layer above (merged from feat/pty-terminal):

• mix e2b.terminal SANDBOX_ID (or --template <tmpl> to create/attach/kill-on-exit) — opens a real terminal into a sandbox PTY from a normal shell: arrow keys, tab-completion, vim/htop, Ctrl-C all work.
• E2bEx.Pty.Terminal.run/2 — the reusable session orchestrator (output loop + linked stdin reader + size-poll + crash handling), over injectable IO hooks so it's fully unit-tested (Bypass-backed, no real tty).
• E2bEx.Pty.InputBatcher — coalesces stdin bytes (and multi-byte escape sequences) into one send_input per ~10ms window.

Ports the E2B CLI's terminal.ts, accommodating two BEAM constraints: raw mode via stty </dev/tty (no setRawMode), and resize via polling (OTP can't trap SIGWINCH). All stty/tty side effects are quarantined in the Mix task; the orchestration logic is pure and tested.

Note: the raw-terminal path itself (stty//dev/tty) is the one piece not automatically tested — it's manual-smoke-only (mix e2b.terminal --template base).

Test Plan (terminal)

• mix test — 153 tests, 0 failures
• mix compile --warnings-as-errors clean; mix help e2b.terminal lists the task
• Manual: mix e2b.terminal --template base opens a working shell; window resize propagates; exit restores the local terminal