ProductOperator experienceHost affordancesHost affordance bridge

Host Affordance Bridge

Explains why selected clipboard, link, and file actions require a typed host-owned bridge across capsule isolation.

Research state: Incomplete

Verification cutoff: 2026-08-12. Revalidate terminal, clipboard, and runtime integration capabilities after this date.

Research question

How can jackin❯ restore selected host-local terminal affordances for containerized agents without weakening the host-container trust boundary?

Headline findings

  • Image clipboard data often never enters the terminal byte stream, so Capsule cannot reconstruct it with input parsing alone.
  • The responsible fix is a host-owned attach client that captures host-only actions and sends typed, bounded requests through authenticated local channels.
  • Clipboard images and files must be validated, staged into container-readable storage, attributed to a session, and cleaned up predictably.
  • URL opening and container-file export use the same capability boundary but require independent allowlists, path policy, and visible operator feedback.
  • OSC 52, Kitty graphics, host-path paste, broad bind mounts, and agent-specific attachment APIs do not provide a complete or safe bridge.
  • The bridge remains an explicit optional capability layer. Unsupported actions fail visibly and do not gain generic host command access.

Method and evidence

The study combines jackin❯ runtime architecture, agent CLI behavior, Ghostty and terminal protocols, herdr’s host-client design, tmux clipboard behavior, remote-terminal products, and platform file/clipboard mechanisms. Sources remain beside the claims they support.

Limitations and open questions

  • Validate paste-trigger behavior across Ghostty, Terminal.app, iTerm2, SSH, tmux, and supported Linux display servers.
  • Select native clipboard libraries and fallbacks by measured capability and permission behavior.
  • Define multi-client attach ownership, staging lifetime, directory export, and destination policy.
  • Keep link-opening and file-export policy narrow enough to prevent arbitrary host execution or writes.

How to read

  1. Host affordance evidence
  2. Product contract and boundaries
  3. Architecture and security
  4. Alternatives and open questions

Custom Operator Tools (`[[tool]]`): Design Exploration

Designs manifest-defined operator tools with explicit inputs, host actions, timeouts, and safe presentation.

01 — Host affordance evidence

Compares clipboard, link, graphics, file-transfer, and remote-terminal mechanisms that inform the Host Affordance Bridge.

On this page

Research questionHeadline findingsMethod and evidenceLimitations and open questionsHow to readRelated work