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.

Review starts in a pager-first Browse surface. Comment on the focused block with c, or use s to start an explicit Range Target for a replacement. In Range Target, y copies the range, c comments on it, and s suggests its replacement. Press ? on a non-input review surface for the complete map below.

Global

Surface	Control	Action
Review	q	done
Decision review	Tab	choose decision
Review	?	help
Review	Ctrl-O	leave open
Reader	Y	toggle side pane
Reader	Ctrl-Y	read Findings

Browse

Surface	Control	Action
Browse	j/k/↑/↓	move block
Browse	Space/f/PgDn/Ctrl-F	page forward
Browse	b/PgUp	page backward
Browse	g/Home · G/End	document bounds
Context	j/k/↑/↓	move
Context	PgUp/PgDn	page
Context	g/G	document bounds
Context	Home/End	line bounds
Browse	c	comment block
Browse	s	select range
Browse	→/Esc	focus Findings

Range

Surface	Control	Action
Range	↑/↓/←/→/hjkl	move target
Range	Space/PgUp/PgDn	page
Range	g/G	document bounds
Range	Home/End	line bounds
Range	y	copy range
Range	c	comment target
Range	s	replace range
Pending suggestion	Enter	continue suggestion
Range	Esc	clear target

Findings

Surface	Control	Action
Findings	j/k/n/p/↑/↓	focus row
Findings	x	include annotation
Findings	e	edit draft
Focused answer	Enter	open answer
Open answer	Space/PgUp/PgDn	page answer

Finish

Surface	Control	Action
Finish	type/Ctrl-E	overall input
Finish input	Tab	insert tab
Finish	Enter	send
Finish	Esc	back

Tools

Surface	Control	Action
Input	Enter	save
Input	Ctrl-J	newline
Input	Alt-Enter	distinct newline
Input	Esc	back
Browse/Range/Context	/ · n/N	find · next/previous
Reader	A	choose source
Artifact	[/]	previous/next
Artifact/Range	F	frontmatter
Folded frontmatter	Enter on …	expand/collapse
Mermaid	m	render/source
Reader	:/#	line/gutters
Question	Q/R/T	ask/refresh/auto-refresh
One file	D	toggle focus
Find/Context	Ctrl-C	cancel
Source picker	j/k	move
Source picker	Enter	open
Source picker	Esc	cancel

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.