python-sdk-reference.md

Droid SDK for Python

Install the package as droid-sdk and import it as droid_sdk.

Overview

The SDK runs a local droid subprocess and exposes two ways to run a turn:

Goal	API
Run one turn and return its result	await run(...)
Run turns in an existing session	session.stream(...)

Use Session when prompts need shared history or session operations such as interruption, compaction, or rewind. There is no session.run(); every session turn goes through stream().

Install and authenticate

pip install droid-sdk

Requirements:

• Python 3.10 or later
• droid on PATH
• an authenticated Droid CLI session or a Factory API key

The SDK uses the Droid CLI's local authentication by default. It reads FACTORY_API_KEY when present; pass api_key= only when the key comes from application configuration. The SDK never places keys in command arguments, logs, or exception messages.

Quick start

Run one turn

importasynciofromdroid_sdkimportrunasyncdefmain() ->None:
result=awaitrun("Summarize this repository.")
ifresult.success:
print(result.text)
else:
print(result.subtype)
asyncio.run(main())

run() starts a session, runs one turn, and closes everything it created. The saved session remains resumable. See Result types for every terminal outcome.

Continue a conversation

importasynciofrompathlibimportPathfromdroid_sdkimportSessionasyncdefrun_turn(session: Session, prompt: str) ->str:
asyncwithsession.stream(prompt) asstream:
asyncfor_instream:
passresult=stream.resultifnotresult.success:
raiseRuntimeError(result.subtype)
returnresult.textasyncdefmain() ->None:
asyncwithSession(cwd=Path.cwd()) assession:
print(awaitrun_turn(session, "What does this project do?"))
print(awaitrun_turn(session, "What should I test first?"))
asyncio.run(main())

The second turn includes context from the first. Exiting the session closes the subprocess and session-owned resources. See Default stream types for every yielded value.

Stream partial events

fromdroid_sdkimportSession, TextDeltaasyncwithSession() assession:
asyncwithsession.stream(
"Explain the failing test.",
include_partial_messages=True,
) asstream:
asyncforeventinstream:
ifisinstance(event, TextDelta):
print(event.text, end="", flush=True)
print()
ifnotstream.result.success:
print(f"Turn ended: {stream.result.subtype}")

The default stream yields complete messages. Set include_partial_messages=True to add deltas and operational events. Both modes yield the terminal result and cache it in stream.result. See Partial stream types for the complete event union.

Core contract

Sessions and turns

A Session owns conversation history, settings, a working directory, and one Droid connection. It accepts one active turn at a time.

A turn begins with session.stream(prompt) and ends when the stream yields a RunResult. Create separate sessions for parallel work.

Results and exceptions

A turn's outcome is a value, not an exception: RunSuccess, RunInterrupted, or RunFailure. Interrupted turns, execution failures, and structured-output failures do not raise. Failures in the machinery around a turn (setup, connection, process, protocol, timeout, and cancellation) raise exceptions.

Ownership

Object	Owner
Resources created by run()	run()
Session used with async with	The context manager
Manually opened Session	The caller
In-process MCP servers	The session

Typing

The package includes py.typed, and the public API type-checks under strict Pyright and mypy. Public unions narrow with isinstance(). High-level value models are immutable dataclasses.

Call	Static return type
run(..., output=None)	RunResult[None]
run(..., output=Model)	RunResult[Model]
run(..., output=JsonSchema(...))	RunResult[JsonObject]
session.stream(...)	RunStream[T, StreamMessage[T]]
Partial session.stream(...)	RunStream[T, StreamEvent[T]]
stream.result	RunResult[T]

Models

Model IDs are strings because availability depends on account and organization policy. Omit model to use the configured default, which lives in ~/.factory/settings.json under sessionDefaultSettings. An unknown model ID is rejected by the backend: the turn returns RunFailure(subtype="error_during_execution") with the rejection message in error.message.

Select a model

fromdroid_sdkimportReasoningEffort, runresult=awaitrun(
"Review this repository.",
model="model-id",
reasoning_effort=ReasoningEffort.HIGH,
)

Omit reasoning_effort to use the model default.

Change the model for later turns:

awaitsession.update_settings(
model="model-id",
reasoning_effort=ReasoningEffort.HIGH,
)

See Update settings for the full update_settings() contract.

Use the Factory Router

The model ID auto selects the Factory Router, which routes each task to the model with the best balance of quality, latency, and cost. Some product surfaces label it Auto Model; the model ID is auto everywhere.

fromdroid_sdkimportrunresult=awaitrun("Review this repository.", model="auto")

Pin a session to the router the same way:

asyncwithSession(model="auto") assession:
...

Move a live session onto the router:

awaitsession.update_settings(model="auto")

Omit reasoning_effort; the router chooses the effort along with the model and ignores a supplied value. session.settings.model reports auto; the underlying model can differ per response.

The model ID auto is unrelated to Mode.AUTO, the default interaction mode, and to Autonomy, the permission level.

See which model handled a response

Assistant messages in the wire create_message notification carry the underlying model in modelId; routerId is "auto" when the router made the choice. High-level messages omit these fields. Subscribe with on_notification():

fromcollections.abcimportMappingdefreport_routing(notification: Mapping[str, object]) ->None:
message=notification.get("message")
ifisinstance(message, Mapping) andmessage.get("role") =="assistant":
print(message.get("modelId"), message.get("routerId"))
unsubscribe=session.on_notification(report_routing, type="create_message")

Wire payloads use camelCase keys and evolve server-side; treat absent keys as normal.

Configure mode-specific models

fromdroid_sdkimportMode, ReasoningEffort, Session, SessionConfigconfig=SessionConfig(
mode=Mode.SPEC,
spec_model="model-id",
spec_reasoning_effort=ReasoningEffort.HIGH,
)
asyncwithSession(model="model-id", config=config) assession:
asyncwithsession.stream("Draft an implementation plan.") asstream:
asyncfor_instream:
pass

The primary model handles Auto turns. spec_model handles Spec turns. Switch modes on a live session with enter_spec() and leave_spec(); see Modes.

Model configuration contract

Field	Type	Used by
model	str | None	run(), Session, update_settings()
reasoning_effort	ReasoningEffort | None	Same
spec_model	str | None	SessionConfig, update_settings()
spec_reasoning_effort	ReasoningEffort | None	Same

None uses the configured default. Setting a Spec field to None through update_settings() clears it.

Sessions

Use a session when turns share history.

Open a session

Session is lazy. It creates the subprocess and session on entry:

asyncwithSession(
cwd=Path.cwd(),
model="auto",
) assession:
asyncwithsession.stream("Review the project.") asstream:
asyncformessageinstream:
handle(message)

model="auto" selects the Factory Router.

Configure behavior and attach handlers with SessionConfig and InteractionHandlers:

fromdroid_sdkimport (
Autonomy,
InteractionHandlers,
PermissionRequest,
PermissionResponse,
SessionConfig,
ToolConfirmationOutcome,
)
defapprove(request: PermissionRequest) ->PermissionResponse:
returnrequest.respond(ToolConfirmationOutcome.PROCEED_ONCE)
config=SessionConfig(
autonomy=Autonomy.LOW,
disabled_tools={"Execute"}, # any iterable of tool IDs works heredisable_builtin_skills=True,
)
asyncwithSession(
config=config,
interactions=InteractionHandlers(on_permission=approve),
) assession:
...

Handlers are plain callables that inspect the request and choose an offered outcome; see Permissions and user input for the full contract.

SessionConfig also accepts mode-specific models, MCP servers, tags, source attribution, machine_id, automatic permission rejection, and native-tool overrides. It does not expose a system-prompt API.

Resume a saved session

asyncwithSession.resume(
session_id,
interactions=InteractionHandlers(on_question=answer),
disabled_tools={"Execute"},
) assession:
asyncwithsession.stream("Continue the previous task.") asstream:
asyncfor_instream:
pass

Get a session ID from session.id, result.session_id, or list_sessions().

Resume restores conversation history, working directory, title, and settings; runtime concerns such as handlers and MCP servers must be attached again (see the table below). It does not accept a new working directory or model.

What persists

Restored	Attach again
Conversation history	Interaction handlers
Working directory	Session-scoped MCP servers
Title	Observability sinks
Session settings

Open and close manually

session=Session()
awaitsession.open()
try:
asyncwithsession.stream("Review the project.") asstream:
asyncfor_instream:
passfinally:
awaitsession.close()

open() and close() are idempotent, but a closed session cannot be reopened. Calling an active method before open() raises SessionNotOpenError.

Concurrent open() calls share one startup attempt. If one waiter is cancelled, startup continues for the others. Cancelling the final waiter cancels startup and completes resource cleanup before the session becomes retryable. close() racing startup waits for startup cleanup and leaves the session closed.

Read session state

print(session.id)
print(session.cwd)
print(session.settings.model)
print(session.settings.mode)

These properties are read-only. settings is an immutable snapshot, replaced when Droid reports a settings change.

Update settings

awaitsession.update_settings(
model="model-id",
reasoning_effort=ReasoningEffort.HIGH,
autonomy=Autonomy.MEDIUM,
disabled_tools={"Execute"},
)

Only supplied fields change. Set nullable Spec-model fields to None to clear them.

update_settings() accepts:

Field	Type
model	str | None
reasoning_effort	ReasoningEffort | None
mode	Mode | None
autonomy	Autonomy | None
spec_model	str | None
spec_reasoning_effort	ReasoningEffort | None
tags	Sequence[SessionTag] | None
compaction_token_limit	int | None
compaction_threshold_check_enabled	bool | None
additional_tools	Iterable[str] | None
enabled_tools	Iterable[str] | None
disabled_tools	Iterable[str] | None
restrict_tools	Iterable[str] | None

It returns UpdateSettingsResult. The result currently has no fields.

Rename a session

awaitsession.rename("Authentication review")

rename(title: str) returns None.

Subscribe to raw notifications

unsubscribe=session.on_notification(handle_notification, type="custom_type")
try:
...
finally:
unsubscribe()

High-level streams ignore unknown notifications. on_notification() exposes them without creating a second client.

List saved sessions

fromdroid_sdkimportlist_sessionsforsavedinawaitlist_sessions(limit=10):
print(saved.id, saved.title, saved.modified_at)

Pass all_workspaces=True to list sessions across working directories.

list_sessions() reads local files without starting Droid. Results are newest first. Timestamps are timezone-aware.

Session construction contract

Session(...) accepts:

Argument	Type
cwd	str | Path | None
model	str | None
reasoning_effort	ReasoningEffort | None
config	SessionConfig | None
interactions	InteractionHandlers | None
runtime	Runtime | None
api_key	str | None

SessionConfig fields:

Field	Type
mode	Mode | None
autonomy	Autonomy | None
spec_model	str | None
spec_reasoning_effort	ReasoningEffort | None
mcp_servers	Sequence[McpServerConfig]
machine_id	str | None
tags	Sequence[SessionTag]
session_source	SessionSource | None
auto_reject_permission_requests	bool | None
disable_builtin_skills	bool | None
additional_tools	Iterable[str] | None
enabled_tools	Iterable[str] | None
disabled_tools	Iterable[str] | None
restrict_tools	Iterable[str] | None

Session.resume(session_id, ...) accepts only values that can be reattached:

Argument	Type
session_id	str
interactions	InteractionHandlers | None
mcp_servers	Sequence[McpServerConfig]
runtime	Runtime | None
api_key	str | None
disabled_tools	Iterable[str] | None
auto_reject_permission_requests	bool | None
disable_builtin_skills	bool | None
session_source	SessionSource | None

Session state schemas

Type	Fields
SessionSettings	model, reasoning_effort, mode, autonomy, spec_model, spec_reasoning_effort, tags, sandbox, additional_tools, enabled_tools, disabled_tools, restrict_tools
SessionSettingsUpdate	model, reasoning_effort, mode, autonomy, spec_model, spec_reasoning_effort, tags, additional_tools, enabled_tools, disabled_tools, restrict_tools, compaction_threshold_check_enabled
SandboxSettings	enabled: bool, mode: str | None = None
SessionTag	name, metadata
SavedSession	id, title, owner, message_count, modified_at, created_at, cwd, is_favorite

Every SessionSettingsUpdate field defaults to None. Its field types match the update_settings() table above.

list_sessions() returns list[SavedSession]. Its filters are cwd, all_workspaces, and limit.

on_notification(callback, type=None) passes Mapping[str, object] to the callback and returns an unsubscribe function.

SessionSource requires platform: SessionPlatform; every other attribution field is optional and defaults to None. Required combinations are validated when converted to the wire protocol.

Streaming and results

Use top-level run() when only the result matters. Session turns always use stream().

session.stream() accepts:

Argument	Type
prompt	str
images	Sequence[Image]
files	Sequence[Document]
output	type[BaseModel] | JsonSchema | None
timeout	float | None
include_partial_messages	bool

Complete messages by default

fromdroid_sdkimportAssistantMessageasyncwithsession.stream("Run the tests.") asstream:
asyncformessageinstream:
ifisinstance(message, AssistantMessage):
print(message.text)

Default stream types

StreamMessage[T] = (
UserMessage|AssistantMessage|ToolCall|ToolResult|HookExecution|ErrorEvent|RunResult[T]
)

session.stream(prompt) yields:

Type	Fields
UserMessage	Conversation-message fields
AssistantMessage	Conversation-message fields
ToolCall	name, tool_use_id, input
ToolResult	tool_use_id, tool_name, content, is_error
HookExecution	hook_id, event_name, matcher, tool_call_id, command, timeout, status, exit_code, stdout, stderr, suppress_output
ErrorEvent	message, error_type, timestamp
RunResult[T]	Terminal result described below

Values appear in delivery order. RunResult[T] is always last.

Include partial events

fromdroid_sdkimportRunResult, TextDeltaasyncwithsession.stream(
"Explain the failing test.",
include_partial_messages=True,
) asstream:
asyncforeventinstream:
ifisinstance(event, TextDelta):
print(event.text, end="", flush=True)
elifisinstance(event, RunResult) andnotevent.success:
print(f"\nTurn ended: {event.subtype}")

Partial stream types

StreamEvent[T] = (
StreamMessage[T]
|TextDelta|TextComplete|ThinkingDelta|ThinkingComplete|ToolCallDelta|ToolProgress|TokenUsageUpdate|WorkingStateChanged|PermissionResolved|SettingsUpdated|SessionTitleUpdated|SessionWorkingDirectoryChanged|McpStatusChanged|McpAuthRequired|McpAuthCompleted
)

With include_partial_messages=True, the stream yields every StreamMessage[T] plus:

Type	Fields
TextDelta	message_id, block_index, text
TextComplete	message_id, block_index
ThinkingDelta	message_id, block_index, text
ThinkingComplete	message_id, block_index, duration
ToolCallDelta	tool_use
ToolProgress	tool_use_id, tool_name, content, update
TokenUsageUpdate	Token-usage fields
WorkingStateChanged	state
PermissionResolved	request_id, tool_use_ids, selected_option
SettingsUpdated	settings
SessionTitleUpdated	title
SessionWorkingDirectoryChanged	cwd
McpStatusChanged	servers, summary
McpAuthRequired	server_name, auth_url, message, state
McpAuthCompleted	server_name, outcome, message

ToolProgress.update is a ToolProgressUpdate:

Type	Fields
ToolProgressUpdate	type, tool_name, status, details, text, error, timestamp, parameters, value_snippet, terminal_id, full_output, subagent_session_id

ToolProgressUpdate.type is "tool_call", "tool_result", "error", "status", or "message".

Unknown high-level events are ignored. Use session.on_notification() when the application needs raw notifications.

Message model

fromdroid_sdkimportAssistantMessage, ConversationMessage, UserMessagecompleted: list[ConversationMessage] = []
asyncwithsession.stream("Explain the failing test.") asstream:
asyncforeventinstream:
ifisinstance(event, (UserMessage, AssistantMessage)):
completed.append(event)
save(event)

ConversationMessage defines the fields shared by user and assistant messages:

Field	Type	Meaning
id	str	Stable message ID
content	tuple[ContentBlock, ...]	Ordered canonical content
text	str	Visible text blocks joined in order
parent_id	str | None	Parent message, when present
created_at	datetime	Timezone-aware creation time
updated_at	datetime	Timezone-aware update time

ContentBlock is a typed union for text, thinking, tool use, tool result, redacted thinking, images, and documents. Narrow blocks with isinstance().

ContentBlock= (
TextBlock|ThinkingBlock|RedactedThinkingBlock|ToolUseBlock|ToolResultBlock|ImageBlock|DocumentBlock
)

Type	Fields
TextBlock	id, text
ThinkingBlock	id, thinking, signature, signature_provider, duration
RedactedThinkingBlock	id, data
ToolUseBlock	id, name, input, thought_signature
ToolResultBlock	id, tool_use_id, content, is_error
ImageBlock	id, source, generated
DocumentBlock	id, source

Message is StreamMessage[T] without RunResult[T]. Partial events are not messages.

TextDelta.message_id and block_index identify the assistant content block that eventually appears in AssistantMessage.content. ToolCall.tool_use_id matches the corresponding ToolUseBlock.id.

A complete message can repeat text already delivered through TextDelta. Use deltas for live rendering and complete messages for persistence. Do not concatenate both.

stream.result.messages is the ordered tuple of complete Message values emitted before the result. It excludes the result and partial events.

Read the result

The terminal RunResult is yielded by the iterator and cached on the stream:

fromdroid_sdkimportRunResultasyncwithsession.stream("Run the tests.") asstream:
asyncformessageinstream:
ifisinstance(message, RunResult):
print(message.subtype)
result=stream.resultifresult.success:
print(result.text)

Reading stream.result before completion raises StreamIncompleteError.

Result types

RunResult[T] is a union of three terminal states:

RunResult[T] =RunSuccess[T] |RunInterrupted[T] |RunFailure[T]

Type	Subtype	success	interrupted
RunSuccess[T]	success	True	False
RunInterrupted[T]	interrupted	False	True
RunFailure[T]	error_during_execution	False	False
RunFailure[T]	error_structured_output	False	False

Field	Type	Meaning
subtype	str	Terminal state
text	str	Final assistant text; reconstructed from deltas if no complete message arrived
messages	tuple[Message, ...]	Complete messages from the turn
usage	Usage | None	Per-turn token and credit usage
duration	timedelta	Wall-clock duration
turn_count	int	SDK turn count, currently 1
session_id	str	Session that ran the turn
output	T | None	Locally adapted structured output
structured_output	FrozenJsonObject | None	Immutable raw structured output
output_validation_error	ValidationError | None	Pydantic failure
structured_output_error	StructuredOutputError | None	Droid failure
error	ErrorEvent | None	Terminal execution error

All result variants retain partial output. RunFailure also exposes error and the server's structured_output_error when available. A successful turn may have no structured output.

RunResult does not define truthiness. Check success or subtype.

Token and context usage

ifresult.usage:
print(result.usage.input_tokens)
print(result.usage.output_tokens)
print(result.usage.cache_read_tokens)
print(result.usage.cache_creation_tokens)
print(result.usage.thinking_tokens)
print(result.usage.factory_credits)

TokenUsageUpdate contains cumulative committed session usage. Context occupancy is separate:

context=awaitsession.context()
print(context.used, context.remaining, context.limit, context.accuracy)

ContextUsage.updated_at records when Droid measured the value.

Type	Fields
Usage	input_tokens, output_tokens, cache_creation_tokens, cache_read_tokens, thinking_tokens, factory_credits
ContextUsage	used, remaining, limit, accuracy, updated_at

Failures and exceptions

asyncwithsession.stream("Run the tests.") asstream:
asyncfor_instream:
passresult=stream.resultifresult.subtype=="interrupted":
print("The turn was interrupted.")
elifresult.subtypein ("error_during_execution", "error_structured_output"):
print(result.error.messageifresult.errorelseresult.subtype)

Setup, connection, process, protocol, and timeout failures raise DroidError subclasses. Python programming errors use normal built-in exceptions. asyncio.CancelledError is never wrapped.

Concurrency

A session may have one active stream. Starting another raises SessionBusyError.

Different sessions may run concurrently.

Timeout

asyncwithsession.stream("Perform a long review.", timeout=60) asstream:
asyncforeventinstream:
handle(event)

On expiry, the SDK interrupts the turn and raises RunTimeoutError.

Interrupt a turn

Another task may stop active work:

awaitsession.interrupt()

The active stream yields an interrupted result if its consumer remains attached. The session stays open.

Cancellation and early exit

Cancelling the task running a turn sends a best-effort interrupt, releases the subscription, then re-raises asyncio.CancelledError.

Use the stream context manager when iteration may stop early:

asyncwithsession.stream("Inspect every test.") asstream:
asyncforeventinstream:
ifshould_stop(event):
break

Context exit interrupts unfinished work. A bare async iterator cannot guarantee immediate cleanup on break. await stream.aclose() explicitly interrupts and detaches an unfinished stream; it is idempotent.

Inputs and outputs

Images and files

Attach images and files to a turn with the images and files options:

fromdroid_sdkimportDocument, Image, runresult=awaitrun(
"Compare these files.",
images=[
Image.from_path("screenshot.png"),
Image.from_bytes(image_bytes, media_type="image/png"),
],
files=[
Document.from_path("report.pdf"),
Document.from_text(source, name="auth.py"),
],
)

The constructors read local data and encode it for the turn. Supported image types are PNG, JPEG, GIF, and WebP; image URLs are unsupported. Invalid local input raises InvalidAttachmentError before the turn starts. Attachments are limited to MAX_ATTACHMENT_BYTES (5 MiB), and PDFs to MAX_PDF_ATTACHMENT_BYTES (3 MiB).

Input schemas

Type	Fields
Image	source: Base64ImageSource
Base64ImageSource	data, media_type
Document	source: TextDocumentSource | PdfDocumentSource
TextDocumentSource	data, name, mime
PdfDocumentSource	data, parsed_data, name, path

Constructor	Returns
Image.from_path(path)	Image
Image.from_bytes(data, media_type=...)	Image
Document.from_path(path)	Document
Document.from_text(text, name=..., mime=...)	Document
Document.from_bytes(data, name=...)	Document

images accepts Sequence[Image]. files accepts Sequence[Document]. Wire payloads use canonical mediaType fields. The optional mime hint on text documents is forwarded with the document.

Return a Pydantic model

fromtypingimportLiteralfrompydanticimportBaseModelfromdroid_sdkimportRunSuccess, runclassFinding(BaseModel):
severity: Literal["low", "medium", "high"]
message: strclassReview(BaseModel):
summary: strfindings: list[Finding]
result=awaitrun(
"Review the authentication code.",
output=Review,
)
ifisinstance(result, RunSuccess) andresult.outputisnotNone:
print(result.output.summary) # success guarantees output when requestedelifresult.output_validation_errorisnotNone:
print(result.output_validation_error)

output accepts a BaseModel subclass, not an arbitrary class. Unsupported types raise TypeError before the turn starts. With output=Review, the return type is RunResult[Review].

When structured output arrives, the SDK validates it against the model. If output was requested, RunSuccess guarantees result.output is set. Missing or invalid output turns the result into RunFailure with subtype error_structured_output; the failure keeps the text, messages, usage, raw structured_output, and output_validation_error for inspection.

Use raw JSON Schema

fromdroid_sdkimportJsonObject, JsonSchema, RunResult, runschema=JsonSchema(
{
"type": "object",
"properties": {"summary": {"type": "string"}},
"required": ["summary"],
}
)
result: RunResult[JsonObject] =awaitrun(
"Summarize the repository.",
output=schema,
)
ifresult.outputisnotNone:
print(result.output["summary"])

JsonSchema accepts an object-shaped schema. Droid reports unsupported or invalid schemas through the normal result subtype.

Output contract

output argument	Return type
Omitted or None	RunResult[None]
type[BaseModel]	RunResult[Model]
JsonSchema	RunResult[JsonObject]

JsonSchema.schema is FrozenJsonObject. Schema mappings must contain only JSON-compatible values; the SDK validates this and freezes them recursively. Raw schema output remains JsonObject.

JsonValue=bool|int|float|str|list["JsonValue"] |dict[str, "JsonValue"] |NoneJsonObject=dict[str, JsonValue]
FrozenJsonValue= (
bool|int|float|str|tuple["FrozenJsonValue", ...]
|Mapping[str, "FrozenJsonValue"]
|None
)
FrozenJsonObject=Mapping[str, FrozenJsonValue]

Both local and Droid-side output failures produce RunFailure with subtype error_structured_output. To tell them apart, check structured_output_error.code: local failures use local_validation_failed (with the Pydantic error in output_validation_error) or local_output_missing; Droid-side failures use Droid's own codes.

Permissions and user input

Autonomy

Autonomy controls which actions require approval in Auto mode:

Level	Behavior
Autonomy.OFF	Ask before every action
Autonomy.LOW	Allow edits and read-only commands
Autonomy.MEDIUM	Allow reversible commands
Autonomy.HIGH	Allow commands without approval

Configure it through SessionConfig:

config=SessionConfig(autonomy=Autonomy.LOW)

Autonomy does not select Auto or Spec mode. Mode controls that.

Handle permission requests

fromdroid_sdkimport (
InteractionHandlers,
PermissionRequest,
PermissionResponse,
Session,
ToolConfirmationOutcome,
)
fromdroid_sdk.permissionsimportCreateFiledefapprove(request: PermissionRequest) ->PermissionResponse:
ifrequest.actionsandall(
isinstance(action, CreateFile) foractioninrequest.actions
):
returnrequest.respond(ToolConfirmationOutcome.PROCEED_ONCE)
returnrequest.respond(ToolConfirmationOutcome.CANCEL)
session=Session(
interactions=InteractionHandlers(on_permission=approve),
)

Droid decides which outcomes are on offer. respond() accepts only an outcome listed in request.options, plus optional comment or edited_spec_content.

An absent handler, an invalid response, or a handler exception cancels the request. Handler failures appear as ErrorEvent values; they do not raise through the active stream.

Answer questions from Droid

fromdroid_sdkimportQuestionRequest, QuestionResponsedefanswer(request: QuestionRequest) ->QuestionResponse:
answers= [
question.answer(question.options[0] ifquestion.optionselse"none")
forquestioninrequest.questions
]
returnrequest.submit(answers)

Cancel the questionnaire:

returnrequest.cancel()

Answers are always strings on the wire. Without a handler, or when a handler fails or returns an invalid shape, the questionnaire is cancelled and the stream receives an ErrorEvent.

question.answer(value) answers one value. question.answer_multiple(values) joins multi-select values with ", " to produce the wire-compatible string.

Handlers run inside the active turn. Use async handlers for I/O, and do not start another turn on the same session from a handler.

Interaction contracts

PermissionHandler=Callable[
[PermissionRequest],
PermissionResponse|Awaitable[PermissionResponse],
]
QuestionHandler=Callable[
[QuestionRequest],
QuestionResponse|Awaitable[QuestionResponse],
]

Type	Fields
InteractionHandlers	on_permission, on_question
PermissionRequest	actions, options, associated_session_ids, plan
PermissionOption	label, value
Plan	text, title
PermissionResponse	selected_option, comment, edited_spec_content
QuestionRequest	tool_call_id, questions
Question	index, topic, question, options, multi_select
QuestionAnswer	index, question, answer
QuestionResponse	cancelled, answers

PermissionAction is a discriminated union:

PermissionAction= (
EditAction|ExecuteAction|CreateFile|AskUserAction|ExitSpecModeAction|ApplyPatchAction|McpToolAction|SandboxViolationAction|DroidShieldViolationAction
)

Every action includes its tool_use, confirmation type, and typed details:

Type	Detail fields
EditAction	file_path, file_name, old_content, new_content
ExecuteAction	full_command, command, extracted_commands, impact_level, risk_level_reason
CreateFile	file_path, file_name, content
AskUserAction	questionnaire, questions, parse_error
ExitSpecModeAction	plan, title
ApplyPatchAction	file_path, file_name, patch_content, old_content, new_content, files
ApplyPatchFile	file_path, file_name, operation, move_to, old_content, new_content
McpToolAction	tool_name, server_name, actual_tool_name, impact_level
SandboxViolationAction	violating_tool_name, target, operation, violation_type, reason, violation_reason, is_org_deny
DroidShieldViolationAction	command, reason

AskUserParseError(message: str, line: int | None = None) records malformed questionnaire details. ApplyPatchFile requires file_path, file_name, and operation ("create", "update", or "delete"); move_to, old_content, and new_content default to None.

ToolConfirmationOutcome defines:

Outcome	Meaning
PROCEED_ONCE	Approve this request
PROCEED_ALWAYS	Persist the offered rule
PROCEED_ALWAYS_EXACT_PATH	Persist the exact file path
PROCEED_AUTO_RUN	Continue with automatic approvals
PROCEED_AUTO_RUN_LOW	Continue at low autonomy
PROCEED_AUTO_RUN_MEDIUM	Continue at medium autonomy
PROCEED_AUTO_RUN_HIGH	Continue at high autonomy
PROCEED_NEW_SESSION	Continue in a new session
PROCEED_NEW_SESSION_LOW	New session at low autonomy
PROCEED_NEW_SESSION_MEDIUM	New session at medium autonomy
PROCEED_NEW_SESSION_HIGH	New session at high autonomy
PROCEED_EDIT	Submit edited plan content
PROCEED_ALWAYS_TOOLS	Persist approval for MCP tools
PROCEED_ALWAYS_SERVER	Persist approval for an MCP server
CANCEL	Reject the request

Only outcomes present in PermissionRequest.options are valid.

Control native tools

config=SessionConfig(
additional_tools={"CustomTool"},
enabled_tools={"Read"},
disabled_tools={"Execute", "Edit"},
restrict_tools={"Read", "Grep"},
)

Each of the four sets has a distinct role:

• additional_tools adds IDs to the catalog.
• enabled_tools enables otherwise available tools.
• disabled_tools removes tools.
• restrict_tools is a restrictive allowlist and never elevates permission.

fortoolinawaitsession.list_tools(model="model-id", mode=Mode.AUTO):
print(tool.id, tool.allowed)

update_settings() accepts the same override fields for later turns. The four override parameters accept any iterable of tool IDs, such as a set, list, or tuple. Passing a bare string raises TypeError.

list_tools() returns list[ToolInfo].

Type	Fields
ToolInfo	id, display_name, description, category, default_allowed, allowed
ListToolsOptions	model, mode, autonomy, spec_model, additional_tools, enabled_tools, disabled_tools, restrict_tools, skip_permissions_unsafe

Tools and extensions

Extension	Use it for
Skills	Reusable instructions and supporting files
In-process MCP tools	Python functions exposed to Droid
External MCP servers	Tools from another process or service
Hooks	Commands run at Droid lifecycle points

Skills

skills=awaitsession.list_skills()
forskillinskills.skills:
print(skill.name, skill.enabled)

skills.project_available reports whether a project skill scope is available; it is None when Droid does not report it.

Enable or disable a skill:

awaitsession.enable_skill("review", scope="project")
awaitsession.disable_skill("legacy", scope="user")

Skills may come from project, personal, built-in, or automation settings.

Skill schemas

Type	Fields
SkillsResult	skills, project_available
SkillInfo	name, description, location, file_path, enabled, user_invocable, version, content, resources, disabled_by
SkillResource	name, path, type
SkillMutationResult	success

scope is "user" or "project". SkillResource.type is "reference" or "asset". SkillInfo.location is "project", "personal", "builtin", or "automation".

In-process MCP tools

In-process servers require the mcp extra (pip install "droid-sdk[mcp]"). Use @tool to expose an annotated Python function:

fromdroid_sdk.mcpimportcreate_sdk_mcp_server, tool@tool("lookup_owner", "Return the owner of a repository file.")asyncdeflookup_owner(path: str) ->str:
returnf"Owner for {path}: platform-team"server=create_sdk_mcp_server(
name="review-tools",
tools=[lookup_owner],
version="1.0.0",
)
config=SessionConfig(mcp_servers=[server])

The decorator derives JSON Schema from type annotations. Invalid input is returned to Droid as a tool error and is not passed to the function.

Tool functions may be synchronous or asynchronous. They may return text or a typed ToolResponse.

The SDK starts an authenticated loopback server and closes it with the session. Attach in-process servers again when resuming.

In-process MCP schemas

Type	Fields
DroidTool	name, description, input_schema, handler, output_schema
SdkMcpServer	name, version, tools
ToolResponse	content, is_error, structured_content

tool(name, description) is a decorator; tool(name, description, function) is the equivalent direct call. A return annotation that describes an object is validated at call time, returned as structured content, and advertised through the MCP outputSchema field.

create_sdk_mcp_server(name, tools, version="1.0.0") returns SdkMcpServer. SdkMcpServer.config is the active HttpMcpServerConfig or None; await server.start() returns that config, and await server.close() stops the server. Sessions normally own these calls.

External MCP servers

External server configs do not need the mcp extra:

fromdroid_sdkimportHttpMcpServerConfig, StdioMcpServerConfigconfig=SessionConfig(
mcp_servers=[
HttpMcpServerConfig(name="docs", url="https://example.com/mcp"),
StdioMcpServerConfig(
name="search",
command="python",
args=["-m", "search_server"],
),
],
)

HTTP, SSE, and stdio transports are supported. HTTP and SSE configurations support headers and OAuth settings.

Inspect connected servers and tools:

servers=awaitsession.list_mcp_servers()
tools=awaitsession.list_mcp_tools()
print(servers.summary)
forserverinservers.servers:
print(server.name, server.status)

Session methods can add, remove, enable, disable, and authenticate external servers. Configuration mutations affect the user's Droid settings. Servers passed through SessionConfig are session-scoped.

Session MCP method	Signature
list_mcp_servers	() -> McpServersResult
list_mcp_tools	() -> list[McpToolInfo]
add_mcp_server	(config) -> McpMutationResult
remove_mcp_server	(name: str) -> McpMutationResult
enable_mcp_server / disable_mcp_server	(name: str) -> McpMutationResult
enable_mcp_tool / disable_mcp_tool	(server_name: str, tool_name: str) -> McpMutationResult
authenticate_mcp_server	(name: str) -> McpMutationResult
cancel_mcp_auth / clear_mcp_auth	(name: str) -> McpMutationResult
submit_mcp_auth_code	(name: str, *, code: str, state: str) -> McpMutationResult
submit_mcp_auth_error	(name: str, *, error: str, state: str, error_description: str | None = None) -> McpMutationResult

External MCP schemas

McpServerConfig= (
StdioMcpServerConfig|HttpMcpServerConfig|SseMcpServerConfig|SdkMcpServer
)

Type	Fields
StdioMcpServerConfig	name, command, args, env
HttpMcpServerConfig	name, url, headers, oauth
SseMcpServerConfig	name, url, headers, oauth
HttpHeader	name, value
McpOAuthOptions	scopes, resource, authorization_server_issuer, client_metadata_url, client_id, client_secret, callback_port, token_endpoint_auth_method
McpServersResult	servers, summary
McpServerStatusInfo	name, status, source, is_managed, error, tool_count, server_type, has_auth_tokens, requires_auth, pending_auth_url, pending_auth_message, pending_auth_state
McpStatusSummary	total, connected, connecting, failed, disabled, config_error
McpConfigError	path, message
McpToolInfo	server_name, name, description, is_enabled, is_read_only, input_schema
McpToolInputSchema	type, properties, required
McpMutationResult	success

oauth accepts McpOAuthOptions or False.

Remove, enable, and disable mutate user-scoped MCP configuration only. These methods do not accept a project-scope argument.

Hooks

There is no Python API for defining hooks; configure them in .factory/hooks.json. Hook execution appears as HookExecution values in the run stream. HookExecution.status is "started", "completed", or "error".

Session lifecycle

Fork, compact, and rewind create successor sessions. The successor is an opened Session that takes over the existing Droid connection; fork() returns it directly, while compact() and rewind() return it on their outcome objects.

Fork

Fork copies the conversation into a new session and continues there.

fork=awaitsession.fork(
title="Alternative approach",
tags=[SessionTag(name="experiment")],
)
asyncwithfork:
asyncwithfork.stream("Try the other strategy.") asstream:
asyncfor_instream:
pass

Compact

Compaction summarizes older conversation history to free context-window space.

outcome=awaitsession.compact(instructions="Keep decisions and unresolved failures.")
asyncwithoutcome.sessionascompacted:
print(outcome.removed_count)

Rewind

Rewind returns the conversation to an earlier message and can restore or delete files changed since.

info=awaitsession.rewind_info(message_id)
outcome=awaitsession.rewind(
message_id,
restore=info.available_files,
delete=info.created_files,
title="Before the failed change",
)
asyncwithoutcome.sessionasrewound:
print(outcome.restored_count, outcome.deleted_count)
print(outcome.failed_restore_count, outcome.failed_delete_count)

info.evicted_files explains files that cannot be restored.

Lifecycle contracts

Method	Arguments	Returns
fork()	title, tags	Opened Session
compact()	instructions	CompactOutcome
rewind_info()	message_id	RewindInfo
rewind()	message_id, restore, delete, title	RewindOutcome

Type	Fields
CompactOutcome	session, removed_count
RewindInfo	available_files, created_files, evicted_files
RewindFileSnapshot	file_path, content_hash, size
RewindFileCreation	file_path
RewindEvictedFile	file_path, reason
RewindOutcome	session, restored_count, deleted_count, failed_restore_count, failed_delete_count

Successor ownership

After a successful replacement:

• the returned successor owns the connection and runtime resources
• the source session becomes retired
• id, cwd, and settings remain readable on the source
• active methods on the source raise SessionReplacedError
• closing the source is a no-op

Replacing a session with an active turn raises SessionBusyError.

Only one replacement may run at a time. open() and another replacement raise SessionBusyError while replacement is active. close() racing a replacement waits; on success it closes the successor, and on rollback it closes the source.

Cancelling a replacement before handoff restores the source to open state. If cancellation arrives after a successor is created, the SDK reloads the source with its attached policies and retires the detached successor. If source restoration fails, the SDK closes the connection rather than leaving an ambiguous owner.

Modes

Spec mode

Spec mode lets Droid inspect a codebase and propose a plan without changing files.

Enter Spec mode

awaitsession.enter_spec(
model="model-id",
reasoning_effort=ReasoningEffort.HIGH,
)

Start directly in Spec mode with SessionConfig(mode=Mode.SPEC).

Leave without approving

awaitsession.leave_spec()

This changes the mode only. It does not approve the plan or start implementation.

Approve a plan

Plan approval arrives through the permission handler:

defapprove(request: PermissionRequest) ->PermissionResponse:
ifrequest.plan:
print(request.plan.text)
returnrequest.respond(ToolConfirmationOutcome.PROCEED_ONCE)
returnrequest.respond(ToolConfirmationOutcome.CANCEL)

Return any offered PROCEED_NEW_SESSION* outcome to hand implementation to a new session. Return PROCEED_EDIT with edited_spec_content to revise the plan. CANCEL ends the turn with an interrupted result.

Mode contract

API	Arguments	Returns
SessionConfig(mode=...)	Mode.AUTO or Mode.SPEC	SessionConfig
enter_spec()	model, reasoning_effort	UpdateSettingsResult
leave_spec()	None	UpdateSettingsResult

Entering or leaving Spec mode only changes settings. Plan approval is an ExitSpecModeAction permission request, and only an offered ToolConfirmationOutcome is valid.

Operations

Observability

fromdroid_sdkimportRuntime, runfromdroid_sdk.observabilityimportLogEvent, ObservabilityclassPrintLogger:
deflog(self, event: LogEvent) ->None:
print(event.level, event.name, event.message)
runtime=Runtime(observability=Observability(logger=PrintLogger()))
result=awaitrun("Check repository status.", runtime=runtime)

Logger, metric, and trace-context sinks are synchronous and best-effort. Sink failures never fail a Droid operation.

Events exclude prompts, messages, thinking, tool inputs and results, file contents, raw process output, stack traces, and credentials.

Observability schemas

Type	Fields or methods
Observability	logger, metrics, tracing
Logger	log(event: LogEvent) -> None
LogEvent	level, name, message, attributes, error
SerializedError	name, message, code
MetricSink	record(event: MetricEvent) -> None
MetricEvent	name, kind, value, unit, attributes
TraceContextProvider	inject(carrier: TraceContext) -> None
TraceContext	traceparent, tracestate

attributes is Mapping[str, str | int | float | bool | None]. Log levels are "debug", "info", "warn", and "error". Metric kinds are "counter" and "histogram". TraceContext is deliberately mutable so tracing providers can inject values into it.

Custom runtime

Runtime holds process configuration:

runtime=Runtime(
executable=Path("/opt/factory/bin/droid"),
args=["--flag"],
env={"EXAMPLE": "value"},
)

Environment entries extend the current process environment when the SDK starts Droid.

Runtime schema

Field	Type
executable	str | Path | None
args	Sequence[str]
env	Mapping[str, str]
observability	Observability | None

API index

Root constants and supporting types

Export	Contract
__version__	Installed package version as str
MAX_ATTACHMENT_BYTES	General attachment limit, 5 * 1024 * 1024
MAX_PDF_ATTACHMENT_BYTES	PDF limit, 3 * 1024 * 1024
ImageMediaType	Supported image MIME literal union
JsonValue, JsonObject	Mutable JSON input/output aliases
FrozenJsonValue, FrozenJsonObject	Recursively immutable JSON aliases
ApplyPatchFile	Per-file patch details documented above
AskUserParseError	message, line
SandboxSettings	enabled, mode
SessionSettingsUpdate	Partial settings notification documented above

Top-level functions

API	Returns	Purpose
run(prompt, **options)	RunResult[T]	Run one turn
list_sessions(**filters)	list[SavedSession]	List saved sessions

run() argument	Type
prompt	str
cwd	str | Path | None
model	str | None
reasoning_effort	ReasoningEffort | None
images	Sequence[Image]
files	Sequence[Document]
output	type[BaseModel] | JsonSchema | None
timeout	float | None
config	SessionConfig | None
interactions	InteractionHandlers | None
runtime	Runtime | None
api_key	str | None

Session

Member	Returns
Session(...)	Lazy Session
Session.resume(id, ...)	Lazy Session
open()	None
close()	None
id	str
cwd	Path | None
settings	SessionSettings
stream()	RunStream[T, E]
interrupt()	None
update_settings()	UpdateSettingsResult
rename()	None
on_notification()	Callable[[], None]
list_tools()	list[ToolInfo]
list_skills()	SkillsResult
enable_skill() / disable_skill()	SkillMutationResult
list_mcp_servers()	McpServersResult
list_mcp_tools()	list[McpToolInfo]
MCP mutation methods	McpMutationResult
context()	ContextUsage
fork()	Opened Session
compact()	CompactOutcome
rewind_info()	RewindInfo
rewind()	RewindOutcome
enter_spec() / leave_spec()	UpdateSettingsResult

RunStream

Member	Returns
Async iteration	StreamMessage[T] or StreamEvent[T] values
result	Cached RunResult[T]
aclose()	None

Main enums

Enum	Values
Mode	AUTO, SPEC
Autonomy	OFF, LOW, MEDIUM, HIGH
ReasoningEffort	See supported values below
ToolCategory	READ, EDIT, EXECUTE, OTHER
ToolConfirmationType	EDIT, EXECUTE, CREATE, ASK_USER, EXIT_SPEC_MODE, APPLY_PATCH, MCP_TOOL, SANDBOX_VIOLATION, DROID_SHIELD_VIOLATION
ToolConfirmationOutcome	Permission outcomes offered by Droid
WorkingState	IDLE, THINKING, STREAMING_ASSISTANT_MESSAGE, WAITING_FOR_TOOL_CONFIRMATION, EXECUTING_TOOL, COMPACTING_CONVERSATION
ContextAccuracy	EXACT, ESTIMATED
McpServerType	STDIO, HTTP, SSE
McpServerStatus	CONNECTING, CONNECTED, DISCONNECTED, FAILED, DISABLED
McpAuthOutcome	SUCCESS, CANCELLED, FAILED
OAuthTokenEndpointAuthMethod	NONE, CLIENT_SECRET_BASIC, CLIENT_SECRET_POST
SessionPlatform	SLACK, WEB, API, SESSIONS_API, JIRA, LINEAR, MICROSOFT_TEAMS, READINESS_REMEDIATION, READINESS_EVALUATION, AUTOMATION, WIKI_GENERATION, WIKI_CI_SETUP, TUI, DESKTOP, ACP, UNKNOWN
SandboxOperation	READ, WRITE, NETWORK, TOOL
SandboxViolationType	FILESYSTEM_READ, FILESYSTEM_WRITE, NETWORK, TOOL
SandboxViolationReason	DENY_LIST, NOT_ALLOWED
ErrorType	CONNECTION_ERROR, PROTOCOL_ERROR, SESSION_ERROR, TIMEOUT_ERROR, DROID_CLIENT_ERROR, PROCESS_EXIT_ERROR, ERROR

ReasoningEffort defines NONE, DYNAMIC, OFF, MINIMAL, LOW, MEDIUM, HIGH, EXTRA_HIGH, and MAX. Model and tool IDs are plain strings, not enums.

On the wire, these enums use the following values:

ToolCategory: read, edit, execute, other
ToolConfirmationType: edit, exec, create, ask_user, exit_spec_mode,
apply_patch, mcp_tool, sandbox_violation, droid_shield_violation
OAuthTokenEndpointAuthMethod: none, client_secret_basic, client_secret_post
SandboxOperation: read, write, network, tool
SandboxViolationType: filesystem-read, filesystem-write, network, tool
SandboxViolationReason: deny-list, not-allowed
SessionPlatform: slack, web, api, sessions_api, jira, linear,
microsoft-teams, readiness-remediation, readiness-evaluation, automation,
wiki-generation, wiki-ci-setup, tui, desktop, acp, unknown

Exceptions

All SDK-defined exceptions derive from DroidError. Python built-ins and asyncio.CancelledError do not.

Exception	Meaning
RunTimeoutError	The turn exceeded its deadline
StreamIncompleteError	A stream result was read before completion
InvalidAttachmentError	A local attachment was invalid
SessionNotOpenError	An operation required an opened session
SessionBusyError	The session already had an active turn or replacement in progress
SessionClosedError	The session was closed
SessionReplacedError	A successor retired the source session
SessionReplacementError	Successor load or source restore failed
SessionNotFoundError	A saved session ID was not found
InvalidWorkingDirectoryError	A working directory is unavailable
DroidConnectionError	The local connection failed
DroidProcessError	The Droid process exited unexpectedly
DroidProtocolError	Protocol negotiation or validation failed

Exception constructor metadata is public:

Exception	Additional constructor fields
RunTimeoutError(message, ...)	request_id, method, timeout_duration
SessionReplacedError(session_id, replacement_session_id)	both session IDs
SessionReplacementError(session_id, replacement_session_id, ...)	both IDs, rollback_error, rollback_failed
SessionNotFoundError(session_id)	session_id
InvalidWorkingDirectoryError(cwd, message=None)	cwd
DroidConnectionError(message, ...)	cwd, exec_path
DroidProcessError(message, ...)	exit_code, signal
DroidProtocolError(message, ...)	code, data

Runnable examples

Run commands from the repository root:

Example	Command	Expected result
Attachments	uv run python examples/attachments.py	Live image, text, and PDF turn
Factory Router	uv run python examples/factory_router.py	Live routed turns with per-response model IDs
Interaction helpers	uv run python examples/interaction_helpers.py	Offline typed responses
Interactions	uv run python examples/interactions.py	Live permission/question turn
Interactive session	uv run python examples/interactive_session.py	Two live turns sharing history
Saved sessions	uv run python examples/list_saved_sessions.py	Local saved-session count
Observability	uv run python examples/observability.py	Offline isolated sink counts
One-shot run	uv run python examples/one_shot.py	Live one-turn result
Resume	uv run python examples/resume_session.py --session-id ID	Live resumed turn
SDK MCP	uv run python examples/sdk_mcp.py	Live in-process MCP result
Session operations	uv run python examples/session_operations.py	Live settings, discovery, fork, and compact
Stream events	uv run python examples/stream_events.py	Live tour of every stream event type
Structured output	uv run python examples/structured_output_model.py	Live validated model output

Live examples require an authenticated local Droid CLI or FACTORY_API_KEY; every model call uses a finite timeout.

Known limitations

• The SDK runs local Droid subprocess sessions only.
• The API is asyncio-only.
• Hooks are configured through Droid files, not Python callbacks.
• Image URLs are not supported by the local runtime.
• One session can run one turn at a time.