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benbrandt merged 2 commits into from
Jun 30, 2026
Merged

fix(unstable-v2): Make all session lifecycle requests consistent #1555

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1b5b820
fix(unstable-v2): make v2 config options non-null arrays
benbrandt Jun 30, 2026
0b609f2
fix(unstable-v2): make load session MCP servers optional
benbrandt Jun 30, 2026
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176 changes: 134 additions & 42 deletions agent-client-protocol-schema/src/v2/agent.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1167,11 +1167,11 @@ pub struct NewSessionResponse {
///
/// Used in all subsequent requests for this conversation.
pub session_id: SessionId,
/// Initial session configuration options if supported by the Agent.
#[serde_as(deserialize_as = "DefaultOnError<Option<VecSkipError<_, SkipListener>>>")]
/// Initial session configuration options.
#[serde_as(deserialize_as = "DefaultOnError<VecSkipError<_, SkipListener>>")]
#[schemars(extend("x-deserialize-default-on-error" = true, "x-deserialize-skip-invalid-items" = true))]
#[serde(default)]
pub config_options: Option<Vec<SessionConfigOption>>,
#[serde(default, skip_serializing_if = "Vec::is_empty")]
pub config_options: Vec<SessionConfigOption>,
/// The _meta property is reserved by ACP to allow clients and agents to attach additional
/// metadata to their interactions. Implementations MUST NOT make assumptions about values at
/// these keys.
Expand All @@ -1190,18 +1190,15 @@ impl NewSessionResponse {
pub fn new(session_id: impl Into<SessionId>) -> Self {
Self {
session_id: session_id.into(),
config_options: None,
config_options: Vec::new(),
meta: None,
}
}

/// Initial session configuration options if supported by the Agent.
/// Initial session configuration options.
#[must_use]
pub fn config_options(
mut self,
config_options: impl IntoOption<Vec<SessionConfigOption>>,
) -> Self {
self.config_options = config_options.into_option();
pub fn config_options(mut self, config_options: Vec<SessionConfigOption>) -> Self {
self.config_options = config_options;
self
}

Expand Down Expand Up @@ -1248,6 +1245,7 @@ pub struct LoadSessionRequest {
/// List of MCP servers to connect to for this session.
#[serde_as(deserialize_as = "DefaultOnError<VecSkipError<_, SkipListener>>")]
#[schemars(extend("x-deserialize-default-on-error" = true, "x-deserialize-skip-invalid-items" = true))]
#[serde(default, skip_serializing_if = "Vec::is_empty")]
pub mcp_servers: Vec<McpServer>,
/// The _meta property is reserved by ACP to allow clients and agents to attach additional
/// metadata to their interactions. Implementations MUST NOT make assumptions about values at
Expand Down Expand Up @@ -1308,11 +1306,11 @@ impl LoadSessionRequest {
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct LoadSessionResponse {
/// Initial session configuration options if supported by the Agent.
#[serde_as(deserialize_as = "DefaultOnError<Option<VecSkipError<_, SkipListener>>>")]
/// Initial session configuration options.
#[serde_as(deserialize_as = "DefaultOnError<VecSkipError<_, SkipListener>>")]
#[schemars(extend("x-deserialize-default-on-error" = true, "x-deserialize-skip-invalid-items" = true))]
#[serde(default)]
pub config_options: Option<Vec<SessionConfigOption>>,
#[serde(default, skip_serializing_if = "Vec::is_empty")]
pub config_options: Vec<SessionConfigOption>,
/// The _meta property is reserved by ACP to allow clients and agents to attach additional
/// metadata to their interactions. Implementations MUST NOT make assumptions about values at
/// these keys.
Expand All @@ -1332,13 +1330,10 @@ impl LoadSessionResponse {
Self::default()
}

/// Initial session configuration options if supported by the Agent.
/// Initial session configuration options.
#[must_use]
pub fn config_options(
mut self,
config_options: impl IntoOption<Vec<SessionConfigOption>>,
) -> Self {
self.config_options = config_options.into_option();
pub fn config_options(mut self, config_options: Vec<SessionConfigOption>) -> Self {
self.config_options = config_options;
self
}

Expand Down Expand Up @@ -1459,11 +1454,11 @@ impl ForkSessionRequest {
pub struct ForkSessionResponse {
/// Unique identifier for the newly created forked session.
pub session_id: SessionId,
/// Initial session configuration options if supported by the Agent.
#[serde_as(deserialize_as = "DefaultOnError<Option<VecSkipError<_, SkipListener>>>")]
/// Initial session configuration options.
#[serde_as(deserialize_as = "DefaultOnError<VecSkipError<_, SkipListener>>")]
#[schemars(extend("x-deserialize-default-on-error" = true, "x-deserialize-skip-invalid-items" = true))]
#[serde(default)]
pub config_options: Option<Vec<SessionConfigOption>>,
#[serde(default, skip_serializing_if = "Vec::is_empty")]
pub config_options: Vec<SessionConfigOption>,
/// The _meta property is reserved by ACP to allow clients and agents to attach additional
/// metadata to their interactions. Implementations MUST NOT make assumptions about values at
/// these keys.
Expand All @@ -1483,18 +1478,15 @@ impl ForkSessionResponse {
pub fn new(session_id: impl Into<SessionId>) -> Self {
Self {
session_id: session_id.into(),
config_options: None,
config_options: Vec::new(),
meta: None,
}
}

/// Initial session configuration options if supported by the Agent.
/// Initial session configuration options.
#[must_use]
pub fn config_options(
mut self,
config_options: impl IntoOption<Vec<SessionConfigOption>>,
) -> Self {
self.config_options = config_options.into_option();
pub fn config_options(mut self, config_options: Vec<SessionConfigOption>) -> Self {
self.config_options = config_options;
self
}

Expand Down Expand Up @@ -1603,11 +1595,11 @@ impl ResumeSessionRequest {
#[serde(rename_all = "camelCase")]
#[non_exhaustive]
pub struct ResumeSessionResponse {
/// Initial session configuration options if supported by the Agent.
#[serde_as(deserialize_as = "DefaultOnError<Option<VecSkipError<_, SkipListener>>>")]
/// Initial session configuration options.
#[serde_as(deserialize_as = "DefaultOnError<VecSkipError<_, SkipListener>>")]
#[schemars(extend("x-deserialize-default-on-error" = true, "x-deserialize-skip-invalid-items" = true))]
#[serde(default)]
pub config_options: Option<Vec<SessionConfigOption>>,
#[serde(default, skip_serializing_if = "Vec::is_empty")]
pub config_options: Vec<SessionConfigOption>,
/// The _meta property is reserved by ACP to allow clients and agents to attach additional
/// metadata to their interactions. Implementations MUST NOT make assumptions about values at
/// these keys.
Expand All @@ -1627,13 +1619,10 @@ impl ResumeSessionResponse {
Self::default()
}

/// Initial session configuration options if supported by the Agent.
/// Initial session configuration options.
#[must_use]
pub fn config_options(
mut self,
config_options: impl IntoOption<Vec<SessionConfigOption>>,
) -> Self {
self.config_options = config_options.into_option();
pub fn config_options(mut self, config_options: Vec<SessionConfigOption>) -> Self {
self.config_options = config_options;
self
}

Expand Down Expand Up @@ -5886,6 +5875,82 @@ mod test_serialization {
);
}

fn test_config_option() -> SessionConfigOption {
SessionConfigOption::select(
"mode",
"Mode",
"ask",
vec![SessionConfigSelectOption::new("ask", "Ask")],
)
}

#[test]
fn test_session_response_config_options_default_empty_and_skip_serializing() {
assert_eq!(
serde_json::to_value(NewSessionResponse::new("sess")).unwrap(),
json!({ "sessionId": "sess" })
);
assert_eq!(
serde_json::to_value(LoadSessionResponse::new()).unwrap(),
json!({})
);
assert_eq!(
serde_json::to_value(ResumeSessionResponse::new()).unwrap(),
json!({})
);
#[cfg(feature = "unstable_session_fork")]
assert_eq!(
serde_json::to_value(ForkSessionResponse::new("fork")).unwrap(),
json!({ "sessionId": "fork" })
);

let json = serde_json::to_value(
NewSessionResponse::new("sess").config_options(vec![test_config_option()]),
)
.unwrap();
assert_eq!(json["configOptions"].as_array().unwrap().len(), 1);
}

#[test]
fn test_session_response_config_options_deserialize_missing_null_and_invalid() {
let missing: NewSessionResponse =
serde_json::from_value(json!({ "sessionId": "sess" })).unwrap();
assert!(missing.config_options.is_empty());

let null: NewSessionResponse = serde_json::from_value(json!({
"sessionId": "sess",
"configOptions": null
}))
.unwrap();
assert!(null.config_options.is_empty());

let wrong_shape: NewSessionResponse = serde_json::from_value(json!({
"sessionId": "sess",
"configOptions": "oops"
}))
.unwrap();
assert!(wrong_shape.config_options.is_empty());

let valid_option = serde_json::to_value(test_config_option()).unwrap();
let mixed: NewSessionResponse = serde_json::from_value(json!({
"sessionId": "sess",
"configOptions": ["oops", valid_option]
}))
.unwrap();
assert_eq!(mixed.config_options.len(), 1);

let load: LoadSessionResponse = serde_json::from_value(json!({})).unwrap();
assert!(load.config_options.is_empty());
let resume: ResumeSessionResponse = serde_json::from_value(json!({})).unwrap();
assert!(resume.config_options.is_empty());
#[cfg(feature = "unstable_session_fork")]
{
let fork: ForkSessionResponse =
serde_json::from_value(json!({ "sessionId": "fork" })).unwrap();
assert!(fork.config_options.is_empty());
}
}

#[test]
fn test_auth_method_agent_serialization() {
let method = AuthMethod::Agent(AuthMethodAgent::new("default-auth", "Default Auth"));
Expand Down Expand Up @@ -6054,6 +6119,33 @@ mod test_serialization {
],
})
);
assert_eq!(
serde_json::to_value(LoadSessionRequest::new("sess_abc123", "/home/user/project"))
.unwrap(),
json!({
"sessionId": "sess_abc123",
"cwd": "/home/user/project",
})
);
assert_eq!(
serde_json::from_value::<LoadSessionRequest>(json!({
"sessionId": "sess_abc123",
"cwd": "/home/user/project"
}))
.unwrap()
.mcp_servers,
Vec::<McpServer>::new()
);
assert_eq!(
serde_json::from_value::<LoadSessionRequest>(json!({
"sessionId": "sess_abc123",
"cwd": "/home/user/project",
"mcpServers": null
}))
.unwrap()
.mcp_servers,
Vec::<McpServer>::new()
);
assert_eq!(
serde_json::to_value(SessionInfo::new("sess_abc123", "/home/user/project")).unwrap(),
json!({
Expand Down
49 changes: 41 additions & 8 deletions agent-client-protocol-schema/src/v2/conversion.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -304,6 +304,13 @@ where
value.map(into_v2_vec_skip_errors)
}

fn option_vec_into_v2_default_skip_errors<T>(value: Option<Vec<T>>) -> Vec<T::Output>
where
T: IntoV2,
{
value.map(into_v2_vec_skip_errors).unwrap_or_default()
}

impl<T> IntoV2 for Vec<T>
where
T: IntoV2,
Expand Down Expand Up @@ -3233,7 +3240,7 @@ impl IntoV1 for super::NewSessionResponse {
Ok(crate::v1::NewSessionResponse {
session_id: session_id.into_v1()?,
modes: None,
config_options: option_vec_into_v1_skip_errors(config_options),
config_options: Some(into_v1_vec_skip_errors(config_options)),
meta: meta.into_v1()?,
})
}
Expand All @@ -3251,7 +3258,7 @@ impl IntoV2 for crate::v1::NewSessionResponse {
} = self;
Ok(super::NewSessionResponse {
session_id: session_id.into_v2()?,
config_options: option_vec_into_v2_skip_errors(config_options),
config_options: option_vec_into_v2_default_skip_errors(config_options),
meta: meta.into_v2()?,
})
}
Expand Down Expand Up @@ -3309,7 +3316,7 @@ impl IntoV1 for super::LoadSessionResponse {
} = self;
Ok(crate::v1::LoadSessionResponse {
modes: None,
config_options: option_vec_into_v1_skip_errors(config_options),
config_options: Some(into_v1_vec_skip_errors(config_options)),
meta: meta.into_v1()?,
})
}
Expand All @@ -3325,7 +3332,7 @@ impl IntoV2 for crate::v1::LoadSessionResponse {
meta,
} = self;
Ok(super::LoadSessionResponse {
config_options: option_vec_into_v2_skip_errors(config_options),
config_options: option_vec_into_v2_default_skip_errors(config_options),
meta: meta.into_v2()?,
})
}
Expand Down Expand Up @@ -3388,7 +3395,7 @@ impl IntoV1 for super::ForkSessionResponse {
Ok(crate::v1::ForkSessionResponse {
session_id: session_id.into_v1()?,
modes: None,
config_options: option_vec_into_v1_skip_errors(config_options),
config_options: Some(into_v1_vec_skip_errors(config_options)),
meta: meta.into_v1()?,
})
}
Expand All @@ -3407,7 +3414,7 @@ impl IntoV2 for crate::v1::ForkSessionResponse {
} = self;
Ok(super::ForkSessionResponse {
session_id: session_id.into_v2()?,
config_options: option_vec_into_v2_skip_errors(config_options),
config_options: option_vec_into_v2_default_skip_errors(config_options),
meta: meta.into_v2()?,
})
}
Expand Down Expand Up @@ -3465,7 +3472,7 @@ impl IntoV1 for super::ResumeSessionResponse {
} = self;
Ok(crate::v1::ResumeSessionResponse {
modes: None,
config_options: option_vec_into_v1_skip_errors(config_options),
config_options: Some(into_v1_vec_skip_errors(config_options)),
meta: meta.into_v1()?,
})
}
Expand All @@ -3481,7 +3488,7 @@ impl IntoV2 for crate::v1::ResumeSessionResponse {
meta,
} = self;
Ok(super::ResumeSessionResponse {
config_options: option_vec_into_v2_skip_errors(config_options),
config_options: option_vec_into_v2_default_skip_errors(config_options),
meta: meta.into_v2()?,
})
}
Expand Down Expand Up @@ -9999,12 +10006,38 @@ mod tests {
assert!(back_to_v1.modes.is_none());
}

#[test]
fn v1_session_response_missing_config_options_becomes_empty_v2_vec() {
let new_response: v2::NewSessionResponse =
v1_to_v2(v1::NewSessionResponse::new("sess")).unwrap();
assert!(new_response.config_options.is_empty());

let load_response: v2::LoadSessionResponse =
v1_to_v2(v1::LoadSessionResponse::new()).unwrap();
assert!(load_response.config_options.is_empty());

let resume_response: v2::ResumeSessionResponse =
v1_to_v2(v1::ResumeSessionResponse::new()).unwrap();
assert!(resume_response.config_options.is_empty());

#[cfg(feature = "unstable_session_fork")]
{
let fork_response: v2::ForkSessionResponse =
v1_to_v2(v1::ForkSessionResponse::new("fork")).unwrap();
assert!(fork_response.config_options.is_empty());
}
}

#[test]
fn v2_session_response_converts_to_v1_without_mode_state() {
let response: v1::NewSessionResponse =
v2_to_v1(v2::NewSessionResponse::new("sess")).unwrap();

assert!(response.modes.is_none());
assert!(matches!(
response.config_options,
Some(config_options) if config_options.is_empty()
));
}

#[test]
Expand Down
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