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gc events is a CLI reflection of the supervisor event APIs. The API is the source of truth, but this page documents the CLI output contract explicitly so users can consume gc events without reverse-engineering it from the OpenAPI document.

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Source of Truth

These CLI formats are projections of the supervisor API and SSE contract:
  • City list API: GET /v0/city/{cityName}/events
  • City SSE API: GET /v0/city/{cityName}/events/stream
  • Supervisor list API: GET /v0/events
  • Supervisor SSE API: GET /v0/events/stream
The underlying DTOs come from the published OpenAPI document:
  • WireEvent
  • WireTaggedEvent
  • EventStreamEnvelope
  • TaggedEventStreamEnvelope
  • HeartbeatEvent
Download the canonical supervisor spec and the gc events JSONL line schema from Schemas, or read the broader event-bus notes in the Supervisor REST API.

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Output Modes

gc events has two output families:
  • List mode: gc events
  • Stream mode: gc events --watch and gc events --follow
There is one exception:
  • Cursor mode: gc events --seq

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List Mode

gc events writes JSON Lines to stdout.
  • Each line is exactly one JSON object.
  • There is no outer array or wrapper object.
  • If nothing matches, stdout is empty.

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City Scope

When a city is in scope, each output line is one WireEvent object from GET /v0/city/{cityName}/events. Example: 
{"actor":"human","message":"hello","seq":21,"subject":"mayor","ts":"2026-04-17T15:20:52.136314-07:00","type":"mail.sent"}

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Supervisor Scope

When no city is in scope and the supervisor API is being used, each output line is one WireTaggedEvent object from GET /v0/events. Example: 
{"actor":"human","city":"mc-city","message":"hello","seq":21,"subject":"mayor","ts":"2026-04-17T15:20:52.136314-07:00","type":"mail.sent"}
The supervisor form adds city because the merged event bus spans multiple cities.

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Stream Mode

gc events --watch and gc events --follow also write JSON Lines to stdout, but the line schema is different from list mode.
  • Each line is exactly one SSE event envelope serialized as JSON.
  • The CLI only emits matching event envelopes.
  • Heartbeat SSE frames are consumed internally and are not written to stdout.
  • If --watch times out without a match, stdout is empty and the command exits successfully.

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City Scope

Each line is one EventStreamEnvelope object, matching the API’s event: event SSE payload. Example: 
{"actor":"human","message":"hello","seq":21,"subject":"mayor","ts":"2026-04-17T15:20:52.136314-07:00","type":"mail.sent"}

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Supervisor Scope

Each line is one TaggedEventStreamEnvelope object, matching the API’s event: tagged_event SSE payload. Example: 
{"actor":"human","city":"mc-city","message":"hello","seq":21,"subject":"mayor","ts":"2026-04-17T15:20:52.136314-07:00","type":"mail.sent"}

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Cursor Mode

gc events --seq does not emit JSONL. It prints a single plain-text cursor to stdout.

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City Scope

The value is the current X-GC-Index head for that city’s event log. Example: 
21

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Supervisor Scope

The value is the composite supervisor cursor used by --after-cursor. Example: 
alpha:4,beta:9,mc-city:21

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Filtering and Shape

The following flags only filter which objects are emitted. They do not change the JSON shape:
  • --type
  • --since
  • --payload-match
  • --after
  • --after-cursor
The same rule applies to both list mode and stream mode.

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Machine-Readable Schema

The downloadable events.json schema validates one JSON object line from list, watch, or follow mode. It contains only framing metadata and $refs into openapi.json:
  • City list lines use WireEvent.
  • Supervisor list lines use WireTaggedEvent.
  • City stream lines use EventStreamEnvelope.
  • Supervisor stream lines use TaggedEventStreamEnvelope.
gc events --seq is not covered by the JSON Schema because it writes plain text, not JSON.

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Transport vs Semantic Type

For stream mode, keep these separate:
  • The SSE event: value is the transport envelope name: event, tagged_event, or heartbeat.
  • The JSON object’s type field is the semantic event type: bead.created, mail.sent, session.woke, and so on.
gc events outputs the JSON payloads and envelopes, not the raw SSE frame text.

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Errors

Successful event queries write only data to stdout. Operational failures are written to stderr as human-readable text and return a non-zero exit status. Examples include:
  • API discovery failure
  • invalid flag combinations such as --after with --after-cursor
  • stream setup failures returned by the API as Problem Details
  • malformed or undecodable stream payloads

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Stability Contract

The CLI does not define independent event DTOs. Its stability contract is:
  • the published supervisor OpenAPI schemas for WireEvent, WireTaggedEvent, EventStreamEnvelope, and TaggedEventStreamEnvelope
  • the explicit CLI framing rules on this page: JSONL for list and stream modes, plain text for --seq, empty stdout for no-match list queries, and heartbeat suppression in stream mode
Last modified on April 19, 2026