Lark Event

Lark Events

Prerequisite: Read ../lark-shared/SKILL.md first for authentication, --as user/bot switching, Permission denied handling, and safety rules.

Core commands

Command	Purpose
lark-cli event list [--json]	List all subscribable EventKeys
lark-cli event schema <EventKey> [--json]	Show an EventKey's params and output schema
lark-cli event consume <EventKey> [flags]	Blocking consume; events → stdout NDJSON
lark-cli event status [--json] [--fail-on-orphan]	Inspect the local bus daemon status
lark-cli event stop [--all] [--force]	Stop the bus daemon

Common flags

Flag	Description
--param key=value / -p	Business params (repeatable; comma-separated for multi-value). Unknown keys fail with valid names listed inline
--jq <expr>	jq expression to filter / transform each event; empty output skips the event
--max-events N	Exit after N events. Default 0 = unlimited
--timeout D	Exit after duration D (e.g. 30s, 2m). Default 0 = no timeout. Whichever of --max-events / --timeout fires first wins
--output-dir <dir>	Write each event as a file (relative paths only; prevents traversal)
--quiet	Suppress ready/exit markers and per-event stderr diagnostics, including drop warnings. This can hide event loss. AI should not use this — it removes readiness and integrity signals
--as user|bot|auto	Identity for the session (see lark-shared)

Examples

# Default: stream every event for the key (no filter, no projection)
lark-cli event consume im.message.receive_v1 --as bot

# List every EventKey of one domain (the authoritative, always-current catalog)
lark-cli event list --domain vc --json

# Grab one sample event to inspect payload shape
lark-cli event consume im.message.receive_v1 --max-events 1 --timeout 30s --as bot

# Run for 10 minutes then auto-exit
lark-cli event consume im.message.receive_v1 --timeout 10m --as bot

# Consume multiple EventKeys concurrently (one shape per process, no dispatcher)
lark-cli event consume im.message.receive_v1          --as bot > receive.ndjson &
lark-cli event consume im.message.reaction.created_v1 --as bot > reaction.ndjson &
wait

Call flow

1. lark-cli event list --json → pick a legal key. --domain <d> narrows to one domain; the domains are application, approval, board, card, im, minutes, task, vc. An unknown domain fails with the valid set listed in the hint.
2. lark-cli event schema <key> --json → read resolved_output_schema + jq_root_path to determine field paths
3. lark-cli event consume <key> [--jq '<expr>'] → consume

Subprocess contract

Ready marker

event consume's stderr emits a fixed line [event] ready event_key=<key>. Parent processes should block on stderr until this line appears, then start reading stdout. Do not fall back to sleep.

stdin EOF = graceful exit

event consume treats stdin close as a shutdown signal (wired for AI subprocess callers). Bounded runs are exempt: when --max-events or --timeout is set (> 0), stdin EOF is ignored and the run exits only via its own bound, timeout, or SIGTERM. For unbounded runs, < /dev/null / nohup / systemd's default StandardInput=null will cause an immediate graceful exit (stderr reason: signal). To keep an unbounded run alive:

• Feed stdin a source that never EOFs: < <(tail -f /dev/null)
• Or run bounded: --max-events N / --timeout D

Exit codes & reason

On exit, the last stderr line is [event] exited — received N event(s) in Xs (reason: ...).

exit code	reason	Trigger
0	reason: limit	--max-events reached
0	reason: timeout	--timeout reached
0	reason: signal	Ctrl+C / SIGTERM / stdin EOF (stdin EOF applies to unbounded runs only)
1	JSON error envelope on stderr	Lark API business failure during pre-consume setup (for example subscription create/delete)
2	JSON error envelope on stderr (no exited line)	Validation failure (unknown EventKey, bad --param / --jq, another bus already connected)
3	JSON error envelope on stderr	Auth failure (missing token, missing scopes)
4 / 5	JSON error envelope on stderr	Network / internal failure (bus startup, handshake, file I/O)

Startup and runtime failures emit a structured JSON envelope on stderr: {"ok":false,"error":{"type","subtype","param","message","hint",...}} (the envelope may also carry top-level identity / _notice siblings). Parse error.type / error.subtype to branch (e.g. missing_scope carries a missing_scopes list), error.param to find the offending flag, and error.hint for the recovery action — do not regex-match message text.

Orchestrators should treat reason: limit/timeout/signal (all exit 0) as "business completion" and non-zero as "failure".

Never kill -9

Avoid kill -9 on consume processes for EventKeys whose PreConsume registers a server-side subscription and unsubscribes on exit (minutes, vc, board keys): kill -9 skips the OAPI unsubscribe and leaks the server-side subscription (symptoms: "subscription already exists" on restart, duplicate event delivery). Keys whose subscription is a durable relation with no cleanup (task, approval keys) do not leak this way, but SIGTERM or closing stdin remains the right shutdown for every key.

One consume, one EventKey (multi-key = multi-shell)

The command takes exactly one positional argument; k1,k2 and wildcards are unsupported. Listening to N keys means N subprocesses — this is intentional:

• One shape per process stdout; no dispatcher logic required in the AI
• Fault isolation (one key failing doesn't affect others)
• Independent --as / --jq / --max-events / --timeout per key

All N consumers share a single bus daemon (UDS local IPC), so the overhead is small

Writing jq via schema

event schema <key> --json is the source of truth for writing --jq. Four things to look at:

(1) Where fields start — see jq_root_path

• Value "." → fields are at the top level, write .chat_id
• Value ".event" → fields are inside a V2 envelope, write .event.chat_id

(2) Field list and types — see resolved_output_schema.properties.<name>

Each field carries type / description, and some also have format. Snippet (from event schema im.message.receive_v1 --json):

{
  "chat_id":     {"type":"string", "format":"chat_id",      "description":"Chat ID, prefixed with oc_"},
  "sender_id":   {"type":"string", "format":"open_id",      "description":"Sender open_id, prefixed with ou_"},
  "create_time": {"type":"string", "format":"timestamp_ms", "description":"Send time as ms-epoch string"}
}

(3) Field semantics — see the format tag

Lark-defined semantic tags (not JSON Schema's standard format). Common values: open_id / chat_id / message_id / timestamp_ms / email. Purpose: distinguish "same string type, different meanings" fields so you can reverse-lookup via API or convert formats.

(4) Decoded state — read the field's description

event consume runs Process hooks that may pre-decode some payload fields (flattening V2 envelopes, rendering .content to plain text, etc.) — behavior differs from raw OAPI. Always read the field's description before writing jq, especially for generic field names like content / data / body / payload.

Why it matters: blindly applying fromjson to an already-decoded text field makes jq error on every event and silently drop it — the consumer looks alive but emits nothing, with only a single WARN line buried on stderr. (This is the general behavior: any jq runtime error skips the event with a one-line WARN; the loop does not abort.)

Don't shortcut the schema: when projecting event schema --json with jq, do not strip .description from properties — that's the field that tells you whether a field is already decoded. Dump the full property objects, not just keys.

---

Aside: --param's valid parameters also live in the schema — the params section lists name / type / required / enum / default / description; section missing = this key accepts no --param.

Topic index

Topic	Reference	Coverage
Application	references/lark-event-application.md	Catalog of Application EventKeys, including application.bot.menu_v6 for custom bot menu push events + flattened event_key / operator fields + jq recipe
Approval	references/lark-event-approval.md	Catalog of 2 Approval EventKeys (approval.instance.status_changed_v4, approval.task.status_changed_v4) + optional/multi subscription_type pre-registration + user-auth subscription lifecycle + flat output field reference
IM	references/lark-event-im.md	Catalog of 12 IM EventKeys + shape notes (flat vs V2 envelope) + im.message.receive_v1 field gotchas (sender_id is open_id only; .content is plain text except for interactive cards) + common jq recipes (filter by chat_type / message_type / sender); for card.action.trigger see also ../lark-im/references/lark-im-card-action-reply.md
Task	references/lark-event-task.md	Catalog of 1 Task EventKey (task.task.update_user_access_v2) + Native V2 envelope shape + task commit types + user/bot subscription notes
VC	references/lark-event-vc.md	Catalog of 7 VC EventKeys (meeting lifecycle participant_meeting_started/joined/ended_v1, vc.note.generated_v1, recording recording_started/transcript_generated/ended_v1) + field reference + source type semantics; the live list is always lark-cli event list --domain vc --json
Minutes	references/lark-event-minutes.md	Catalog of 1 Minutes EventKey (minutes.minute.generated_v1) + field reference + source type semantics (meeting only)
Whiteboard	references/lark-event-whiteboard.md	Catalog of 1 Board EventKey (board.whiteboard.updated_v1) + per-whiteboard subscription model (requires -p whiteboard_id=<token>) + payload field reference (whiteboard_id / operator_ids triple-id)