Transport: replace tmux keystroke delivery with harness-native input

[woltspace-jerpint]

Problem

Message delivery to running sessions is tmux keystroke emulation: set-buffer + paste-buffer + separate Enter. Every harness has its own TUI paste quirks, and we're accumulating timing hacks to compensate:

• Claude: Enter inside a paste = literal newline → separate Enter keystroke (Fix telegram paste not submitting — separate Enter from paste #326)
• Codex: Enter arriving <~0.5s after a paste gets folded into it → paste_settle: 0.5 property (Add codex harness (stacked on #356) #357)
• Pasting while codex is mid-response interrupts/queues oddly (observed live, unfixed)

paste_settle works but it's a race dressed as a config value — flagged by jerpint at review as something to fix properly.

Direction

Per-harness programmatic input where it exists, keystrokes only as fallback:

• opencode: opencode serve HTTP API — real message injection
• claude/codex: no injection API today (Feature: Send messages to running agents without stopping them anthropics/claude-code#21419/#27441 open). ACP (Agent Client Protocol) adapters exist for both via Zed; opencode speaks ACP natively
• Long-term: ACP as the delivery layer makes woltspace the ACP client — big change (woltspace renders the conversation), overlaps the session-interior redesign

The harness table already supports this shape: deliver() becomes a per-harness strategy (api | acp | tmux-paste) instead of tmux-paste with per-harness timing knobs.

Non-goals for now

The tmux-attach model for humans stays — this is about how the bot delivers messages, not how humans interact.

🤖 Generated with Claude Code