Create sessions

Opens a live agent session in the caller's org — the row every surface (the CLI's outer agent, hanzo.bot, the console, chat) hangs its activity off.

POST /v1/agent/sessions

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Address	`https://api.hanzo.ai/v1/agent/sessions`
Method	`POST`
Operation	`post_agent_sessions`
Auth	`Authorization: Bearer $HANZO_API_KEY`

Opens a live agent session in the caller's org — the row every surface (the CLI's outer agent, hanzo.bot, the console, chat) hangs its activity off. A session with a parentSessionId becomes a subagent of that session and inherits its root, so one flow is one tree; without one it is itself a root. Registering with a terminal status records a session that has already finished.

Request

18 fields, body application/json (required).

Field	In	Type	Required	Description
`account`	body	string	—	Account is which subscription or API account under that provider served the run, up to 256 characters.
`actor`	body	string	—	Actor is the "org/sub" identity to record the session under, up to 256 characters.
`agent`	body	string	—	Agent is the label the surface opening this session calls itself by ("hanzo-dev").
`budget_micro_usd`	body	integer (int64)	—	BudgetMicroUSD caps what this session may spend, integer micro-USD.
`cwd`	body	string	—	Cwd is the directory the session starts in, up to 1024 characters.
`host`	body	string	—	Execution context — where this session runs (all optional).
`parentSessionId`	body	string	—	ParentSessionID makes this a subagent of that session: it inherits the parent's root, so one flow stays one tree.
`project`	body	string	—	The readable build (provenance.go): which product this session builds, and whether its story may be read by the world.
`provider`	body	string	—	Account tag — the linked AI account this session ran under (login manager).
`published`	body	boolean	—	Published opens this session's story to the public build route.
`repo`	body	string	—	Repo is the code being worked on, up to 512 characters.
`room`	body	string	—	Room is the collaborative room this run was started in (HIP-0523), so a space view can list the sessions of one room.
`status`	body	string	—	Status opens the session in one of running, paused, done or error.
`target`	body	string	—	Target names a run-target the org has registered.
`taskRunId`	body	string	—	TaskRunID is that workflow's particular run, same bound.
`taskWorkflowId`	body	string	—	TaskWorkflowID links this session to the hanzoai/tasks workflow that executes it, up to 256 characters.
`terminal`	body	string	—	Terminal is the URL this session's live terminal is published at, so the console can watch it.
`title`	body	string	—	Title is the human line a card shows, up to 512 characters.

Response

Status	Body	Meaning
`201`	agent.sessionView	created
`default`	problem-details	refused

201 body — 45 fields.

Field	In	Type	Always	Description
`account`	body	string	—	Account is which subscription or API account under that provider served it.
`actor`	body	string	—	Actor is WHO this session belongs to, as "org/sub" — the same identity a run is billed under.
`agent`	body	string	—	Agent is the label the surface running this session calls itself by ("hanzo-dev"), up to 128 characters.
`base`	body	string	—	Base is the branch the run started from.
`branch`	body	string	—	Branch is the branch the run pushes its work to, and the only one it may write.
`children`	body	integer (int64)	—	Children is the DIRECT fan-out — how many sessions name this one as parent — and not the size of the subtree.
`createdAt`	body	string	—	CreatedAt is when the row was written, same format.
`cwd`	body	string	—	Cwd is the directory the session is working in NOW, not the one it started in: a linked shell moves around, and a card showing where `hanzo link` was run answers "which work is this" with something that was true once.
`endedAt`	body	string	—	EndedAt is when it reached done or error, same format.
`environment`	body	string	—	Environment is where the run executes: "sandbox" for a Hanzo sandbox, or the id of the org's machine it was routed to (the same id Target carries).
`events`	body	integer (int64)	—	Events is how many turns the session's log holds, counted at read time.
`host`	body	string	—	Execution context (mission-control): the machine/repo/cwd a card shows and the run-target a session is dispatched to.
`id`	body	string	—	ID is the session's handle, minted here as "sess_" + 32 hex characters.
`kind`	body	string	—	Kind is what sort of run this session is the view of — "coding" for a coding run.
`lastEvent`	body	agent.lastEventView	—
`lastEvent.actor`	body	string	—	Actor is who produced the turn, defaulted to the calling principal when the writer named nobody.
`lastEvent.at`	body	string	—	At is when the turn was recorded, RFC 3339 in UTC to the second.
`lastEvent.kind`	body	string	—	Kind is what the turn was, from the log's closed six: message, tool-call, spawn, log, status, control.
`lastEvent.preview`	body	string	—	Preview is the first 240 bytes of the event's payload, cut without regard for the JSON inside it — it is a string to SHOW, never a value to parse.
`lastEvent.seq`	body	integer (int64)	—	Seq is that event's position in the session's log — monotonic from 1, per session.
`mode`	body	string	—	Mode is what the run may do to its repository: "build" edits, commits and pushes its branch; "plan" reads and answers with a plan, writing nothing.
`org`	body	string	—	Org is the caller's OWN tenant, echoed so a client can build the public build URL (/builds/:org/:project) without a second call or a guess.
`parentSessionId`	body	string	—	ParentSessionID is the session that spawned this one, making this a subagent of it.
`pr`	body	string	—	PR is the address of the pull request the run proposed.
`progress`	body	agent.sessionProgress	—
`progress.activity`	body	string	—	Activity is the one line saying what the run is doing right now ("running the reaper's tests"), up to 120 characters, in the model's words.
`progress.at`	body	string	—	At is when this was determined, RFC 3339 in UTC to the second.
`progress.estimated`	body	boolean	—	Estimated says a MODEL produced this, from the run's transcript, and it may be wrong.
`progress.pct`	body	integer (int64)	—	Pct is how much of the run is done, 0 to 100.
`progress.phase`	body	string	—	Phase is what shape the run is in: running, blocked, done, error, or unknown when nothing has estimated it yet.
`project`	body	string	—	The readable build: the product this session built and whether its story is public (provenance.go).
`provider`	body	string	—	Provider is the linked AI account's provider (claude \| codex \| hanzo \| …) that served this run.
`published`	body	boolean	—	Published is the author's decision to let anyone read this session's story at the public build route.
`repo`	body	string	—	Repo is the code the session is working on, as the surface reported it.
`room`	body	string	—	Room is the collaborative room this run was started in (HIP-0523), empty when it came from anywhere else — a CLI, a schedule, an API call.
`rootSessionId`	body	string	—	RootSessionID is the top of this session's tree, inherited from the parent and shared by every node in one flow.
`sandbox`	body	string	—	Sandbox is the id of the sandbox the run works in ("m_" and 24 hex), the handle its terminal and its screen are opened with (/v1/sandbox/{id}/terminal, /screen).
`startedAt`	body	string	—	StartedAt is when the session opened, RFC 3339 in UTC to the second.
`status`	body	string	—	Status is one of exactly four: running, paused, done, error.
`target`	body	string	—	Target is the registered run-target this session is dispatched to — a machine the org claimed, resolved same-org when it was set, so it can never point at another tenant's computer.
`taskRunId`	body	string	—	TaskRunID is that workflow's particular run.
`taskWorkflowId`	body	string	—	TaskWorkflowID is the hanzoai/tasks durable workflow that actually EXECUTES this session — this registry is the view, control and stream layer over it.
`terminal`	body	string	—	Terminal is where this session can be WATCHED — the URL the machine published for its live terminal.
`title`	body	string	—	Title is the human line a card shows ("ship the landing page"), up to 512 characters.
`updatedAt`	body	string	—	UpdatedAt is the session's last-activity clock, same format.

Failure carries the platform error shape — see Errors.

Examples

CLI

SDK

HTTP

MCP

hanzo agent sessions create

.ts

.py

.go

.rs

.java

import { Configuration, AgentApi } from 'hanzoai';

const api = new AgentApi(new Configuration({ accessToken: process.env.HANZO_API_KEY }));
const { data } = await api.postAgentSessions({ account: "<account>", actor: "<actor>" });

from hanzoai.cloud import ApiClient, Configuration
from hanzoai.cloud.api import AgentApi

client = ApiClient(Configuration(access_token=os.environ["HANZO_API_KEY"]))
result = AgentApi(client).post_agent_sessions(account="<account>", actor="<actor>")

cfg := hanzoai.NewConfiguration()
cfg.AddDefaultHeader("Authorization", "Bearer "+os.Getenv("HANZO_API_KEY"))
client := hanzoai.NewAPIClient(cfg)

resp, _, err := client.AgentAPI.PostAgentSessions(context.Background()).Execute()
if err != nil {
	return err
}

use hanzo_client::apis::{configuration::Configuration, agent_api};

let mut cfg = Configuration::new();
cfg.bearer_access_token = std::env::var("HANZO_API_KEY").ok();

let result = agent_api::post_agent_sessions(&cfg, Default::default()).await?;

import ai.hanzo.cloud.ApiClient;
import ai.hanzo.cloud.api.AgentApi;

ApiClient client = new ApiClient();
client.setBearerToken(System.getenv("HANZO_API_KEY"));

var result = new AgentApi(client).postAgentSessions();

curl -X POST https://api.hanzo.ai/v1/agent/sessions \
  -H "Authorization: Bearer $HANZO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
       "account": "<account>",
       "actor": "<actor>"
     }'

MCP reaches agent through the agent tool, which names its 38 operations with its own verbs — this one among them, under a name only MCP declares. describe explains any of them:

curl -X POST https://api.hanzo.ai/v1/mcp \
  -H "Content-Type: application/json" \
  -d '{
       "jsonrpc": "2.0",
       "id": 1,
       "method": "tools/call",
       "params": {
         "name": "describe",
         "arguments": {
           "op": "list_agents"
         }
       }
     }'

Agent API · All Hanzo APIs · Interactive reference

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