zjctl

zjctl

Use the shipped Rust zjctl CLI to inspect and control Zellij sessions, tabs, and panes safely from agents. Prefer zjctl over raw zellij action commands when the operation is supported.

Scope

Use this skill for:

• listing Zellij sessions
• listing, focusing, or opening tabs
• listing, reading, writing, focusing, or opening panes
• sending keys to panes

Do not use this skill to:

• invent unsupported CLI flags — check --help first
• bypass safety guards casually — --no-guard requires intentional use
• use raw zellij action when zjctl supports the operation
• assume another implementation exists — the Rust implementation in this repository is canonical

First checks, always

Before using zjctl in a fresh session:

1. Confirm the CLI is available and check its help:

   zjctl --help
   

2. If not on $PATH, install the canonical root crate from the zjctl repository:

   git clone https://github.com/mrmans0n/zjctl /tmp/zjctl && cargo install --path /tmp/zjctl
   

3. Do not assume old flags or commands still exist — verify against --help output.

If updating this skill, verify against source files:

• src/cli.rs — command and flag surface
• src/models.rs — JSON response structs
• src/commands/ — command behavior and dry-run mapping
• src/identity.rs — tab and pane identity resolution
• src/safety.rs — self-write guard behavior
• src/error.rs — error names, fields, and exit codes

Global flags

Flag	Default	Description
-f, --format <json|table|quiet>	json	Output format
-n, --dry-run	off	Show command without executing
-q, --quiet	off	Suppress non-error output
-s, --session <SESSION>	—	Target session (overrides ZELLIJ_SESSION_NAME)
--no-guard	off	Bypass self-write safety guard

Session resolution

Commands under tabs and panes require a session. Resolution order:

1. --session <name> flag
2. ZELLIJ_SESSION_NAME environment variable
3. Error: not_in_session, exit code 4

sessions list does not require a session.

Commands

Sessions

zjctl sessions list

Tabs

zjctl tabs list
zjctl tabs focus <index-or-name>
zjctl tabs open [--name NAME] [--layout LAYOUT] [-- COMMAND...]

Panes

zjctl panes list [--tab <index-or-name>]
zjctl panes read <pane> [--full] [--ansi]
zjctl panes write <pane> <text>
zjctl panes send-keys <pane> <keys...>
zjctl panes focus <pane>
zjctl panes open [--direction DIR] [--floating] [--name NAME] [--cwd CWD] [--tab-id ID] [-- COMMAND...]

Identity resolution

Tabs accept:

• Numeric 0-based index (e.g. 0, 2)
• Exact tab name from the session (e.g. "main")

Panes accept:

• Qualified ID: terminal_N or plugin_N
• Bare integer N — normalized to terminal_N
• Exact pane title (must be unambiguous among non-plugin panes)

Ambiguous or missing identifiers return invalid_target, exit code 1.

JSON contracts

Success responses

Sessions list:

{"sessions":[{"name":"main"}]}

Tabs list:

{"tabs":[{"index":0,"name":"main","active":true,"tab_id":0}]}

Panes list (note: command, cwd, title can be null):

{"panes":[{"id":"terminal_0","command":"zsh","cwd":"/repo","title":"main","focused":true,"floating":false,"tab_id":0,"tab_name":"main"}]}

Pane read:

{"pane_id":"terminal_7","content":"$ echo hello\nhello\n$"}

Successful mutation (write, send-keys, focus):

{"ok":true}

Tab open:

{"tab_id":1}

Pane open:

{"pane_id":"terminal_12"}

Dry run (any mutation):

{"dry_run":true,"command":["zellij","action","write-chars","--pane-id","terminal_7","hello"]}

Error responses

Errors are emitted as JSON on stderr:

{"error":"invalid_target","message":"Pane not found: foo","exit_code":1}

Known errors:

Error	Exit	Extra fields	When
unknown_command	1	—	Unrecognized command
missing_argument	1	—	Required argument missing
invalid_target	1	—	Tab/pane identifier not found or ambiguous
zellij_error	2	command	Zellij subprocess failed
self_write_blocked	3	target, self	Write/send-keys to own pane blocked
not_in_session	4	—	No session resolved
parse_error	5	—	Failed to parse zellij output

Safety guards

panes write and panes send-keys include self-write protection:

1. The target pane is resolved.
2. The resolved pane ID is compared against ZELLIJ_PANE_ID.
3. If they match, the command fails with self_write_blocked (exit 3).
4. The guard runs even during --dry-run — dry-run output is only emitted after the guard passes.
5. --no-guard bypasses the protection. Use only when the agent has verified the target is intentional or the user explicitly requests it.
6. If ZELLIJ_PANE_ID is not set, the guard is skipped (no self to protect).

Self-write block example:

{"error":"self_write_blocked","message":"Refusing to write to own pane (terminal_8). Use --no-guard to override.","exit_code":3,"target":"terminal_8","self":"terminal_8"}

Usage patterns

Find a pane by title, run a command, read output

# 1. Find the target pane
zjctl panes list | jq '.panes[] | select(.title == "build-runner")'
# → {"id":"terminal_5", ...}

# 2. Write a command to it
zjctl panes write terminal_5 "cargo test --quiet"

# 3. Send Enter to execute
zjctl panes send-keys terminal_5 Enter

# 4. Wait, then read output
sleep 3
zjctl panes read terminal_5
# → {"pane_id":"terminal_5","content":"...test results..."}

Focus a tab by name, then list its panes

# 1. List tabs to confirm the name exists
zjctl tabs list
# → {"tabs":[{"index":0,"name":"editor","active":true,...},{"index":1,"name":"tests",...}]}

# 2. Focus the target tab
zjctl tabs focus tests
# → {"ok":true}

# 3. List panes in that tab
zjctl panes list --tab tests
# → {"panes":[{"id":"terminal_3",...},{"id":"terminal_4",...}]}

Open a pane, capture its ID, run a command

# 1. Open a floating pane with a working directory
zjctl panes open --floating --name "scratch" --cwd /tmp
# → {"pane_id":"terminal_12"}

# 2. Write a command to the new pane using the returned ID
zjctl panes write terminal_12 "ls -la"
zjctl panes send-keys terminal_12 Enter

Dry-run before writing to a non-current pane

# 1. Preview what zjctl would execute
zjctl --dry-run panes write terminal_7 "rm -rf build/"
# → {"dry_run":true,"command":["zellij","action","write-chars","--pane-id","terminal_7","rm -rf build/"]}

# 2. If the preview looks correct, run for real
zjctl panes write terminal_7 "rm -rf build/"
# → {"ok":true}

Handle invalid_target by relisting

# 1. Attempt to read a pane that may have been closed
zjctl panes read terminal_99
# stderr: {"error":"invalid_target","message":"Pane not found: terminal_99","exit_code":1}

# 2. Relist panes to find the correct target — don't retry blindly
zjctl panes list
# → {"panes":[{"id":"terminal_0",...},{"id":"terminal_3",...}]}

# 3. Use the correct ID
zjctl panes read terminal_3

Guardrails

• Prefer zjctl over raw zellij action when zjctl supports the operation.
• Always verify --help output in a fresh session before using commands.
• If an operation is not supported by zjctl, say so plainly and consider raw zellij action only as a last resort.
• Treat --no-guard as a deliberate override, not a default workaround.
• The Rust implementation in this repository is canonical.
• When updating this skill, cross-check against the source files listed in "First checks, always".