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Reference

Create an agent session

Starts a session of an agent, pinned to its current version unless `agent_version` names another.

Checked 2026-09-28

Starts a session of an agent, pinned to its current version unless agent_version names another. Requires a secret key until end-user ownership is implemented. The session starts idle; :send starts its first turn.

Not available yet. Sylphx Agents is declared in the registry but no backend serves it: every call answers 501 with the problem code UNIMPLEMENTED.

Path POST https://api.sylphx.com/v1/orgs/acme/projects/shop/envs/production/agent_sessions
Scope agents:sessions
Effect write — a successful call changes state.
Collection agent_sessions
Query agent_session_id, validate_only

#Request

Field	Type	What it is
`parent`	`string`	The parent to create in. Required.
`agent_session_id`	`string`	The session id, the final name segment; the server assigns one when empty.
`agent_session`	`AgentSession`	The session to create; only caller-writable fields are read. Required.
`validate_only`	`bool`	Validate and return the result without writing anything.

#AgentSession

Field	Type	What it is
`name`	`string`	`orgs/{org}/projects/{project}/envs/{env}/agent_sessions/{agent_session}`.
`meta`	`ResourceMeta`	Resource metadata.
`agent`	`string`	The Agent the session talks to. Required.
`agent_version`	`string`	The AgentVersion the session pinned; the Agent's current version when unset at create.
`title`	`string`	A short title; set by the caller or summarised by the runtime.
`environment`	`EnvironmentSpec`	The environment for this session; when omitted, use the pinned Agent version's default. An explicit value replaces that default.
`credentials`	`map<string, CredentialBinding>`	Session-scoped credential bindings, keyed by the tool or MCP credential name. Values are references or opaque handles, never secret values.
`profiles`	`ProfileMount[]`	Granted platform Profiles to mount when the session starts, each by resource name and mode. The runtime never puts profile values in events.

#ResourceMeta

Field	Type	What it is
`labels`	`map<string, string>`	Caller-writable, indexed labels (AIP-122 label rules).
`annotations`	`map<string, string>`	Caller-writable, unindexed annotations.
`display_name`	`string`	Caller-writable human-readable name.

#EnvironmentSpec

Field	Type	What it is
`shape`	`string`	A Sylphx Sandboxes shape; empty gives sessions no environment.
`idle_standby`	`duration`	Put the environment in standby after this long idle, 1m to 24h; default 10m.
`template`	`string`	The Sandboxes image: `template:<name>` or an artifact image by digest, passed unchanged to the lease's `image` field.
`repo`	`RepositorySpec`	The repository to prepare inside the fresh lease, if any.
`egress`	`LeaseNetwork`	The lease's outbound policy, using the Sandboxes network contract.
`budget`	`LeaseBudget`	The lease's CPU and cost ceiling, separate from model and tool spend.
`ttl`	`duration`	The lease's maximum wall time, passed to Sandboxes as `ttl`. The lease is released when the session ends even if this bound has not been reached.

#CredentialBinding

Field	Type	What it is
`secret`	`string`	A Kernel Secret of this environment, by name. One of the `source` group.
`connection`	`string`	A Kernel Connection (a third-party OAuth installation), by name. One of the `source` group.
`end_user_provider`	`string`	The end user's own grant in Sylphx Auth's agent token vault, by provider id; the session's end user must hold it. One of the `source` group.
`placement`	`string`	How the value is sent: `bearer` (default), `header:<Name>` or `query:<name>`.
`handle`	`string`	An opaque credential handle issued for this session, resolved only at egress. This is never a credential value. One of the `source` group.

#ProfileMount

Field	Type	What it is
`name`	`string`	`orgs/{org}/projects/{project}/envs/{env}/profiles/{profile}`. Required.
`mode`	`string`	`read_only` (default) or `write_back`. Only a write_back grant saves changes at session end while its lease still answers; empty is read_only.

#RepositorySpec

Field	Type	What it is
`uri`	`string`	The repository URI. Access uses the session's bound credential handles. Required.
`revision`	`string`	The commit or ref to check out; empty uses the repository's default branch.

#LeaseNetwork

Field	Type	What it is
`egress`	`EgressPolicy`	Default ALLOW. One of `allow`, `deny`, `allowlist`.
`allowed_domains`	`string[]`	Hosts reachable when `egress` is ALLOWLIST: exact names or one leading `.` wildcard label, for example `api.openai.com`, `.github.com`.
`allowed_cidrs`	`string[]`	Public CIDRs reachable when `egress` is ALLOWLIST.

#LeaseBudget

Field	Type	What it is
`max_cpu_seconds`	`int64`	End CPU_BUDGET after this many vCPU-seconds of guest CPU time.
`max_cost_micros`	`int64`	End COST_BUDGET once the shape's list price times wall seconds reaches this many millionths of a US dollar.

#Response

Field	Type	What it is
`name`	`string`	`orgs/{org}/projects/{project}/envs/{env}/agent_sessions/{agent_session}`.
`uid`	`string`	`ases_<cell><ulid>`; never reused. Output only.
`meta`	`ResourceMeta`	Resource metadata.
`agent`	`string`	The Agent the session talks to. Required.
`agent_version`	`string`	The AgentVersion the session pinned; the Agent's current version when unset at create.
`end_user`	`string`	The Sylphx Auth end user the session belongs to, set from the caller's end-user session; empty for a session a secret key started. An end user reads and changes only their own sessions. Output only.
`title`	`string`	A short title; set by the caller or summarised by the runtime.
`state`	`SessionState`	The session's state. Output only. One of `idle`, `running`, `awaiting_approval`, `awaiting_client`, `failed`.
`turn_count`	`int64`	The number of turns started, from 0. Output only.
`last_event_sequence`	`int64`	The sequence of the newest event, from 0. Output only.
`create_time`	`timestamp`	When the session was created. Output only.
`update_time`	`timestamp`	When the last event was appended. Output only.
`usage`	`SessionUsage`	What the session has used so far. Output only.
`environment_lease`	`string`	The Sylphx Sandboxes lease attached to the session, while it has one. Output only.
`environment`	`EnvironmentSpec`	The environment for this session; when omitted, use the pinned Agent version's default. An explicit value replaces that default.
`credentials`	`map<string, CredentialBinding>`	Session-scoped credential bindings, keyed by the tool or MCP credential name. Values are references or opaque handles, never secret values.
`profiles`	`ProfileMount[]`	Granted platform Profiles to mount when the session starts, each by resource name and mode. The runtime never puts profile values in events.

#ResourceMeta

Field	Type	What it is
`generation`	`int64`	Increases by one on every change to `spec`. Output only.
`etag`	`string`	Strong ETag (AIP-154): changes on any change to spec, status, or metadata. Send it back as `If-Match` or `etag` to make Update and Delete conditional; a mismatch fails with ABORTED / 409 `ETAG_MISMATCH`. Output only.
`create_time`	`timestamp`	When the Resource was created. Output only.
`update_time`	`timestamp`	When the Resource last changed. Output only.
`delete_time`	`timestamp`	Set while the Resource is being deleted. Output only.
`labels`	`map<string, string>`	Caller-writable, indexed labels (AIP-122 label rules).
`annotations`	`map<string, string>`	Caller-writable, unindexed annotations.
`display_name`	`string`	Caller-writable human-readable name.
`creator`	`string`	The principal that created the Resource. Output only.

#SessionUsage

Field	Type	What it is
`active_turn_duration`	`duration`	Time turns were active. Output only.
`gateway_calls`	`int64`	Tool calls made through the gateway. Output only.
`spend_micros`	`int64`	Spend so far in micro-USD, models and tools together. Output only.

#EnvironmentSpec

Field	Type	What it is
`shape`	`string`	A Sylphx Sandboxes shape; empty gives sessions no environment.
`idle_standby`	`duration`	Put the environment in standby after this long idle, 1m to 24h; default 10m.
`template`	`string`	The Sandboxes image: `template:<name>` or an artifact image by digest, passed unchanged to the lease's `image` field.
`repo`	`RepositorySpec`	The repository to prepare inside the fresh lease, if any.
`egress`	`LeaseNetwork`	The lease's outbound policy, using the Sandboxes network contract.
`budget`	`LeaseBudget`	The lease's CPU and cost ceiling, separate from model and tool spend.
`ttl`	`duration`	The lease's maximum wall time, passed to Sandboxes as `ttl`. The lease is released when the session ends even if this bound has not been reached.

#CredentialBinding

Field	Type	What it is
`secret`	`string`	A Kernel Secret of this environment, by name. One of the `source` group.
`connection`	`string`	A Kernel Connection (a third-party OAuth installation), by name. One of the `source` group.
`end_user_provider`	`string`	The end user's own grant in Sylphx Auth's agent token vault, by provider id; the session's end user must hold it. One of the `source` group.
`placement`	`string`	How the value is sent: `bearer` (default), `header:<Name>` or `query:<name>`.
`handle`	`string`	An opaque credential handle issued for this session, resolved only at egress. This is never a credential value. One of the `source` group.

#ProfileMount

Field	Type	What it is
`name`	`string`	`orgs/{org}/projects/{project}/envs/{env}/profiles/{profile}`. Required.
`mode`	`string`	`read_only` (default) or `write_back`. Only a write_back grant saves changes at session end while its lease still answers; empty is read_only.

#RepositorySpec

Field	Type	What it is
`uri`	`string`	The repository URI. Access uses the session's bound credential handles. Required.
`revision`	`string`	The commit or ref to check out; empty uses the repository's default branch.

#LeaseNetwork

Field	Type	What it is
`egress`	`EgressPolicy`	Default ALLOW. One of `allow`, `deny`, `allowlist`.
`allowed_domains`	`string[]`	Hosts reachable when `egress` is ALLOWLIST: exact names or one leading `.` wildcard label, for example `api.openai.com`, `.github.com`.
`allowed_cidrs`	`string[]`	Public CIDRs reachable when `egress` is ALLOWLIST.
`blocked_cidrs`	`string[]`	The ranges blocked under every policy. Output only.

#LeaseBudget

Field	Type	What it is
`max_cpu_seconds`	`int64`	End CPU_BUDGET after this many vCPU-seconds of guest CPU time.
`max_cost_micros`	`int64`	End COST_BUDGET once the shape's list price times wall seconds reaches this many millionths of a US dollar.

#Errors

UNAUTHENTICATED — No valid key or token was presented.
PERMISSION_DENIED — The key lacks the method's permission.
UNKNOWN_FIELD — The request has a field the schema does not know.
INVALID_FIELD — A field failed validation.
RESOURCE_ALREADY_EXISTS — A Resource with this name exists.
IDEMPOTENCY_KEY_REUSED — An Idempotency-Key was reused with another body.
IDEMPOTENCY_IN_PROGRESS — The first call with this Idempotency-Key is still running.
PLAN_LIMIT_REACHED — The plan's limit is reached.
SPEND_LIMIT_REACHED — The org's spend limit is reached.

Every error arrives in the body Errors describes.

#Examples

curl -X POST "https://api.sylphx.com/v1/orgs/acme/projects/shop/envs/production/agent_sessions" \
  -H "Authorization: Bearer $SYLPHX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"agent":"…"}'

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