Headless cli

Headless CLIs: codex, opencode, agy, kimi

Call the four local coding CLIs non-interactively from a Bash call (the claude -p equivalent). Follow the rules below — they stop a call from hanging or returning empty. Setup, config, and the why behind each rule live in the repo README (pointer at the bottom).

Models below are examples — substitute your configured default for each CLI. There is no fixed task→model mapping. Use whichever CLI/model you've set up; the rules and recipes are model-agnostic.

Pick one

	codex exec	opencode run	agy -p	kimi -p
Model	your ChatGPT-plan model @ your default effort	your default provider/model · -m provider/model to switch	your default Gemini model	your default Kimi model (effort is config-only)
Auth	ChatGPT sub — no env key	provider API key in env (auto-injected)	Google OAuth — no env key	Kimi sub OAuth — no env key
Concurrency	parallel OK	parallel: isolate data dir	parallel OK	parallel OK
Files	read + edit (sandbox)	read/grep/edit — absolute paths only	read/edit, native	read/edit, native — no permission flag needed
Structured out	--output-schema	--format json	none — ask in prompt	--output-format stream-json
Use	go-to peer for any problem, esp. multi-turn (resume)	good supplement; parallel fan-out	good supplement; easiest file read/write	good supplement; clean NDJSON + machine-readable session id

Invoke

# ask / explain (let them read files themselves)
codex exec "explain ./src and read ./config.toml" < /dev/null
opencode run "read /abs/path/README.md and list the headings"   # opencode: ABSOLUTE paths only
agy -p "read ./config.toml and summarize it" < /dev/null
kimi -p "read ./config.toml and summarize it"

# edit files
codex exec --sandbox workspace-write "fix the bug in ./app.py and save" < /dev/null
opencode run --dangerously-skip-permissions "add tests for utils.py"
agy --dangerously-skip-permissions -p "add tests for utils.py" < /dev/null
kimi -p "add tests for utils.py"        # kimi: -p ALREADY auto-approves; -y/--auto ERROR out with -p

# pick model / effort — no fixed task→model mapping: codex is a strong go-to peer for ANY problem
# (esp. multi-turn), the others are good supplements
codex exec -c model_reasoning_effort="high" "..." < /dev/null
opencode run -m provider/model "..."                     # opencode effort flags hang — don't use
agy --model "Gemini 3.5 Flash (Low|Medium|High)" -p "..." < /dev/null  # switch within Gemini only
kimi -m provider/model -p "..."          # effort is config-only ([thinking] effort), no CLI flag

# structured JSON output
codex exec --output-schema schema.json -o out.json "extract X as JSON" < /dev/null
opencode run --format json "..."
kimi --output-format stream-json "..."  # NDJSON: {"role":"assistant","content":…} + a session.resume_hint line
# agy: no JSON flag — say "respond with only JSON: {...}" and parse loosely

# continue a session — codex keeps full context + model/effort across rounds;
# codex prints `session id: <uuid>` on STDERR (capture `2> r1.log`, then `grep -oP 'session id: \K\S+' r1.log`);
# use `resume <id>` whenever another codex call might land in between (`--last` = most recent session globally, races)
codex exec resume --last "now add error handling" < /dev/null   # or: resume <id>
opencode run -c "now add tests"                                 # or: -s <id>
agy -c "now add tests" < /dev/null                             # or: --conversation <id>
kimi -S <session_id> -p "now add tests"    # -S, NOT the `-r` its own output tells you to use (-r HANGS headlessly)
# kimi session id: read it from the stream-json meta line —
#   sid=$(kimi --output-format stream-json -p "..." | jq -r 'select(.type=="session.resume_hint").session_id')
# multi-turn peer loop needs a stop condition: ask for "end with VERDICT: APPROVED or VERDICT: REVISE + reasons";
# loop `resume <id>` on REVISE, stop on APPROVED (cap ~5 rounds)

# big / multi-line prompt: file → arg for codex/agy, → STDIN for opencode
{ echo "Critique this:"; echo; cat plan.md; } > /tmp/p.txt
codex exec "$(cat /tmp/p.txt)" -o /tmp/out.md < /dev/null
cat /tmp/p.txt | opencode run > /tmp/out.md                # NOT a giant "$(...)" arg

# parallel fan-out — codex/agy/kimi as-is; opencode needs a private data dir per proc
ocp(){ local d; d=$(mktemp -d); XDG_DATA_HOME="$d/s" XDG_STATE_HOME="$d/t" opencode run "$@"; rm -rf "$d"; }
codex exec "task A" < /dev/null > a.md &
ocp "task B" > b.md &
agy -p "task C" < /dev/null > c.md &
kimi -p "task D" > d.md &
wait
# many opencode calls, capped at 5:
printf '%s\n' "${prompts[@]}" | xargs -P 5 -I{} bash -c 'd=$(mktemp -d); XDG_DATA_HOME=$d XDG_STATE_HOME=$d opencode run "$1" > "out-$$.md"; rm -rf "$d"' _ {}

# codex built-in repo review
codex exec review < /dev/null

# generate an image — codex only (the others have no image models). State the aspect or you get a square.
codex exec --sandbox workspace-write \
  "Generate an image: <description>. 16:9 landscape. Save it into the current directory as ./cover.png, then print its path and dimensions." < /dev/null

Hard rules (break one = wasted / hung call)

codex

• Always append < /dev/null (else it waits on stdin).
• -o <file> to capture the answer (raw stdout is noisy). --skip-git-repo-check outside a git repo. --sandbox workspace-write to edit.
• Generated images land OUTSIDE your cwd. image_gen writes to ~/.codex/generated_images/<session-uuid>/exec-*.png; the run then reports success with no file where you expect one unless you both pass --sandbox workspace-write AND say "save it into the current directory as ./name.png". Recovery: ls -t ~/.codex/generated_images/*/*.png | head -1.
• Say the aspect ratio or you get a square (measured: unprompted → 1254×1254; "16:9 landscape" → native 1672×941). codex has a shell, so asking for an exact size makes it chain ImageMagick. Budget a couple of minutes and tens of thousands of tokens per image — background it.

opencode

• Parallel → private data dir per proc: XDG_DATA_HOME=$(mktemp -d) XDG_STATE_HOME=$(mktemp -d) opencode run … (else concurrent runs hit database is locked). Only for parallel one-shots — -c/-s continue must use the default dir.
• Big prompts via stdin (cat f | opencode run), never a large "$(cat f)" arg (it hangs).
• Reads: pin ABSOLUTE paths — "read this EXACT path, don't modify: /abs/…" (relative paths can get mangled by the model → exit 0, empty stdout). Files outside the repo root can't be read — paste inline. Reviewing code with intra-repo imports: don't let it read at all — paste the code inline + "do NOT read any files".
• Verify the output — exit code is useless (exits 0 even on a rejected read). cat prompt.txt | timeout 300 opencode run > out.txt 2> err.txt, then check out.txt non-empty; empty ⇒ retry once.
• Non-empty ≠ complete — check the document SHAPE too. Long structured outputs can arrive truncated: the model prints the review progressively across intermediate turns (lost) and stdout captures only the final tail. Prevent: append "deliver the COMPLETE <deliverable> as ONE single final message — your final message is the only thing captured" to the prompt. Detect: expected header/section missing (e.g. no ## Verdict) ⇒ rerun with that instruction.
• inotify_add_watch … No space left on device at startup is NON-FATAL — it's the inotify watch limit (fs.inotify.max_user_watches), not disk; only the file watcher dies, the run continues. Do NOT kill/retry on this error alone — an empty out-file mid-run + this error looks like a dead run but isn't: check the process is still alive (pgrep, growing stderr log) before declaring it dead. (Fix: raise fs.inotify.max_user_watches, persist in /etc/sysctl.conf.)
• Never -f/--file (eats the message), --variant, --thinking (can hang). Writing needs --dangerously-skip-permissions; large-model runs can be slow (minutes) — background them.

agy

• Stdin hang fixed in agy 1.1.1 (-p no longer reads stdin when the prompt is given as a flag; pre-1.1.1 hung forever on a non-closing pipe from an agent harness). Recipes keep < /dev/null anyway — zero cost, required on <1.1.1.
• Gemini only by convention: switch only within Gemini models (… (Low|Medium|High), Gemini 3.1 Pro (Low|High)) unless you deliberately want otherwise. Set your own configured default.
• Reads/writes natively; --dangerously-skip-permissions to write. No JSON flag. --print-timeout needs a unit (10m). Kill stuck procs with pkill -9 -x agy (never -f agy).

kimi

• -p is already fully autonomous — it reads and writes files with no permission flag. Do NOT add -y/--auto: both are a hard error: Cannot combine --prompt with … and the run does nothing.
• Resume with -S <id>, never -r <id>. Every headless run ends with To resume this session: kimi -r …, but -r drops into the interactive TUI and hangs forever on a non-closing pipe. -S <id> -p "…" resumes correctly (context verified across rounds).
• No stdin hang (< /dev/null not needed, harmless). Parallel-safe — no shared-DB lock. Effort lives in ~/.kimi-code/config.toml ([thinking] effort), there is no CLI flag.
• Login dies with a bare fetch failed: on an IPv4-only host — its JS runtime honours DNS order verbatim and won't fall back from IPv6. Fix host-wide: echo 'precedence ::ffff:0:0/96 100' | sudo tee -a /etc/gai.conf (verify with getent ahosts <host>, not getent hosts).

Flags

codex (codex exec --help): -m <model> · -c model_reasoning_effort="low|medium|high|xhigh" · -s/--sandbox read-only|workspace-write|danger-full-access · -o <file> · --output-schema <file> · --json · -C/--cd <dir> · --add-dir <dir> · -p/--profile <name> · --skip-git-repo-check · exec resume --last|<id> · exec review · --dangerously-bypass-approvals-and-sandbox (only if sandbox breaks).

opencode (opencode run --help): -m provider/model · --format json · --dangerously-skip-permissions · -c/--continue · -s/--session <id> · redirect stdout > file (no -o). Avoid --variant, --thinking, -f. Note -p = --password, not print.

kimi (kimi --help): -p/--prompt <text> (headless) · -m/--model <alias> · --output-format text|stream-json · -S/--session <id> · -c/--continue · --add-dir <dir> · --plan · --skills-dir <dir> · subcommands login, upgrade, doctor, provider list. Avoid -y/--auto (incompatible with -p) and -r (hangs).

agy (agy --help): -p/--print (headless) · --model "Gemini 3.5 Flash (High)" (Gemini only) · --dangerously-skip-permissions · -c/--continue · --conversation <id> · --add-dir <dir> · --sandbox (opt-in; OFF by default) · --print-timeout 10m (unit required). No JSON flag.

Runtime notes

• Keys: provider API keys (e.g. DEEPSEEK_API_KEY) must be visible to the non-interactive call. Agent harnesses don't source ~/.bashrc/~/.profile, so inject the key via your harness's env mechanism (for Claude Code: the settings.json env block) — then no per-call export is needed. Fallback if a call auth-fails: export DEEPSEEK_API_KEY="$(grep -oP 'DEEPSEEK_API_KEY="?\K[^" ]+' ~/.bashrc | tail -1)".
• Orchestrating: wait for CLIs IN-TURN — launch, then poll in the SAME turn (until [ -s out.md ]; do sleep 20; done, bounded), verify → retry-once → synthesize before ending. Don't go idle expecting a wake-on-completion.
• Setup, config, login, sandbox fix, and the why behind these rules → the repo README (README.md).