Subspace

Review one Markdown file in your terminal.

Subspace includes a companion agent skill that launches its focused reader in Zellij, tmux, CMUX, Herdr, Ghostty, or Apple Terminal. It sends comments and suggested edits directly back to the invoking agent, attached to exact text.

Install and try it

brew install spacedock-dev/tap/subspace-beta

Linux, or macOS without Homebrew

Install the prebuilt binary directly. The installer resolves the latest release through the canonical latest-release URL http://spacedock.md/latest-release/subspace, verifies the release's checksum before anything is placed, and installs subspace-tui into ~/.local/bin:

curl -fsSL https://raw.githubusercontent.com/spacedock-dev/subspace/main/install.sh | sh

Add ~/.local/bin to your PATH if it is not already there.

sr path/to/file.md

Install the companion agent skill

In Claude Code, add the marketplace and install the plugin:

claude plugin marketplace add spacedock-dev/marketplace
claude plugin install subspace@subspace-beta

In Codex, add the marketplace and the plugin:

codex plugin marketplace add spacedock-dev/subspace-beta --json
codex plugin add subspace@subspace-beta --json

From an agent session with the companion skill installed, invoke:

/r path/to/file.md

In Codex, invoke:

$r path/to/file.md

Add --allow-question to let the reviewer ask your agent questions about the file while the review stays open, and read the answer in the same surface:

/r --allow-question path/to/file.md

$r --allow-question path/to/file.md

Agent integration

Ask your agent to open the review with the Subspace skill. This example uses tmux and lets the reviewer ask questions during the review:

$r --allow-question path/to/file.md tmux

Press Q to ask about the file. The agent keeps a poller active while the review is open. It answers from the same file that you can see in Subspace. You can continue the review while the agent prepares the answer.

When you finish, Subspace returns comments and suggested edits to the agent. Each item stays attached to the text that you selected.

Press ? from any non-editor review surface to see its current keyboard shortcuts.

Subspace renders Mermaid diagrams and tables natively in the terminal, not as plain fenced code.

License

The Subspace skills are released under Apache 2.0. The subspace-tui tool itself is not currently open source. The permissions and attributions for external code linked into the tool are published in THIRD_PARTY_NOTICES.txt.