microsoft · lszomoru · Jun 4, 2026 · Jun 4, 2026 · Jun 4, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -38,8 +38,11 @@ Spec version: `0.3.0`
 - Removed the `additions`, `deletions`, and `files` fields from
   `ChangesetSummary`. Aggregate counts now live on `SessionSummary.changes`;
   per-changeset views derive their own totals from `ChangesetState.files`.
-- Renamed the `ChangesetSummary` interface to `Changeset` (catalogue entry
-  on `SessionSummary.changesets`). The on-the-wire shape is unchanged.
+- Moved the `changesets` catalogue from `SessionSummary` to
+  `SessionState`. The `session/changesetsChanged` action now updates
+  `state.changesets` directly instead of `state.summary.changesets`.
+- Renamed the `ChangesetSummary` interface to `Changeset`. The
+  on-the-wire shape is unchanged.
 - Renamed the `UserMessage` type to `Message` and surfaced it consistently
   across turn state (`Turn.message`, `ActiveTurn.message`, `PendingMessage.message`)
   and the actions that carry it (`session/turnStarted`,

diff --git a/clients/go/CHANGELOG.md b/clients/go/CHANGELOG.md
@@ -25,7 +25,8 @@ tag whose matching `## [X.Y.Z]` heading is missing from this file.
 
 ### Changed
 
-- Renamed the `ChangesetSummary` type to `Changeset` (catalogue entry on `SessionSummary.changesets`). The on-the-wire shape is unchanged.
+- Renamed the `ChangesetSummary` type to `Changeset`. The on-the-wire shape is unchanged.
+- Moved the `changesets` catalogue from `SessionSummary` to `SessionState`. The `session/changesetsChanged` action now updates `state.changesets` directly instead of `state.summary.changesets`.
 
 ### Removed
 

diff --git a/clients/go/ahp/reducers.go b/clients/go/ahp/reducers.go
@@ -499,7 +499,11 @@ func ApplyActionToSession(state *ahptypes.SessionState, action ahptypes.StateAct
 		state.Summary.Activity = a.Activity
 		return ReduceOutcomeApplied
 	case *ahptypes.SessionChangesetsChangedAction:
-		state.Summary.Changesets = append([]ahptypes.Changeset(nil), a.Changesets...)
+		if a.Changesets == nil {
+			state.Changesets = nil
+		} else {
+			state.Changesets = append([]ahptypes.Changeset(nil), a.Changesets...)
+		}
 		return ReduceOutcomeApplied
 	case *ahptypes.SessionConfigChangedAction:
 		if state.Config == nil {

diff --git a/clients/go/ahptypes/actions.generated.go b/clients/go/ahptypes/actions.generated.go
@@ -443,8 +443,9 @@ type SessionActivityChangedAction struct {
 
 // The {@link Changeset | catalogue of changesets} the agent host
 // advertises for this session changed. Replaces
-// `state.summary.changesets` entirely (full-replacement semantics) — set
-// to `undefined` to clear the catalogue.
+// {@link SessionState.changesets | `state.changesets`} entirely
+// (full-replacement semantics) — set to `undefined` to clear the
+// catalogue.
 //
 // Producers dispatch this whenever entries are added or removed. The
 // fan-out happens through this action so observers see catalogue

diff --git a/clients/go/ahptypes/notifications.generated.go b/clients/go/ahptypes/notifications.generated.go
@@ -70,8 +70,7 @@ type SessionRemovedParams struct {
 //     {@link SessionSummary | `SessionSummary`} changes for a session the
 //     server has surfaced via `listSessions()` or `root/sessionAdded`.
 //     Servers MAY coalesce or debounce updates for noisy fields (for example,
-//     `modifiedAt` bumps while a turn is streaming, or rapidly changing
-//     `changesets`) at their discretion.
+//     `modifiedAt` bumps while a turn is streaming) at their discretion.
 //   - Clients that have no cached entry for `session` MAY ignore the
 //     notification; it is not a substitute for `root/sessionAdded`.
 type SessionSummaryChangedParams struct {
@@ -185,12 +184,6 @@ type PartialSessionSummary struct {
 	Agent *AgentSelection `json:"agent,omitempty"`
 	// The working directory URI for this session
 	WorkingDirectory *URI `json:"workingDirectory,omitempty"`
-	// Catalogue of changesets the server can produce for this session. Each
-	// entry advertises a subscribable view of file changes (uncommitted,
-	// session-wide, per-turn, etc.) and the URI template the client expands
-	// before subscribing. See {@link Changeset} for the full shape and
-	// {@link /guide/changesets | Changesets} for an overview of the model.
-	Changesets []Changeset `json:"changesets,omitempty"`
 	// Aggregate summary of file changes associated with this session. Servers
 	// may populate this to give clients a quick at-a-glance view of the
 	// session's footprint (e.g., for list rendering) without requiring the

diff --git a/clients/go/ahptypes/state.generated.go b/clients/go/ahptypes/state.generated.go
@@ -555,6 +555,12 @@ type SessionState struct {
 	// and the host propagates them into this list (typically with the
 	// container's `clientId` set and `children` populated).
 	Customizations []Customization `json:"customizations,omitempty"`
+	// Catalogue of changesets the server can produce for this session. Each
+	// entry advertises a subscribable view of file changes (uncommitted,
+	// session-wide, per-turn, etc.) and the URI template the client expands
+	// before subscribing. See {@link Changeset} for the full shape and
+	// {@link /guide/changesets | Changesets} for an overview of the model.
+	Changesets []Changeset `json:"changesets,omitempty"`
 	// Additional provider-specific metadata for this session.
 	//
 	// Clients MAY look for well-known keys here to provide enhanced UI.
@@ -609,12 +615,6 @@ type SessionSummary struct {
 	Agent *AgentSelection `json:"agent,omitempty"`
 	// The working directory URI for this session
 	WorkingDirectory *URI `json:"workingDirectory,omitempty"`
-	// Catalogue of changesets the server can produce for this session. Each
-	// entry advertises a subscribable view of file changes (uncommitted,
-	// session-wide, per-turn, etc.) and the URI template the client expands
-	// before subscribing. See {@link Changeset} for the full shape and
-	// {@link /guide/changesets | Changesets} for an overview of the model.
-	Changesets []Changeset `json:"changesets,omitempty"`
 	// Aggregate summary of file changes associated with this session. Servers
 	// may populate this to give clients a quick at-a-glance view of the
 	// session's footprint (e.g., for list rendering) without requiring the

diff --git a/clients/kotlin/CHANGELOG.md b/clients/kotlin/CHANGELOG.md
@@ -26,7 +26,8 @@ versions (`*-SNAPSHOT`) are explicitly rejected by the publish pipeline; bump
 
 ### Changed
 
-- Renamed the `ChangesetSummary` type to `Changeset` (catalogue entry on `SessionSummary.changesets`). The on-the-wire shape is unchanged.
+- Renamed the `ChangesetSummary` type to `Changeset`. The on-the-wire shape is unchanged.
+- Moved the `changesets` catalogue from `SessionSummary` to `SessionState`. The `session/changesetsChanged` action now updates `state.changesets` directly instead of `state.summary.changesets`.
 
 ### Removed
 

diff --git a/clients/kotlin/src/main/kotlin/com/microsoft/agenthostprotocol/Reducers.kt b/clients/kotlin/src/main/kotlin/com/microsoft/agenthostprotocol/Reducers.kt
@@ -924,9 +924,7 @@ public fun sessionReducer(state: SessionState, action: StateAction): SessionStat
     )
 
     is StateActionSessionChangesetsChanged -> state.copy(
-        // Clear the field entirely when no changesets are provided, matching
-        // TS `{ ...summaryWithoutChangesets }` semantics (omits the key).
-        summary = state.summary.copy(changesets = action.value.changesets),
+        changesets = action.value.changesets,
     )
 
     is StateActionSessionConfigChanged -> {

diff --git a/...tlin/src/main/kotlin/com/microsoft/agenthostprotocol/generated/Notifications.generated.kt b/...tlin/src/main/kotlin/com/microsoft/agenthostprotocol/generated/Notifications.generated.kt
@@ -192,14 +192,6 @@ data class PartialSessionSummary(
      * The working directory URI for this session
      */
     val workingDirectory: String? = null,
-    /**
-     * Catalogue of changesets the server can produce for this session. Each
-     * entry advertises a subscribable view of file changes (uncommitted,
-     * session-wide, per-turn, etc.) and the URI template the client expands
-     * before subscribing. See {@link Changeset} for the full shape and
-     * {@link /guide/changesets | Changesets} for an overview of the model.
-     */
-    val changesets: List<Changeset>? = null,
     /**
      * Aggregate summary of file changes associated with this session. Servers
      * may populate this to give clients a quick at-a-glance view of the

diff --git a/clients/kotlin/src/main/kotlin/com/microsoft/agenthostprotocol/generated/State.generated.kt b/clients/kotlin/src/main/kotlin/com/microsoft/agenthostprotocol/generated/State.generated.kt
@@ -899,6 +899,14 @@ data class SessionState(
      * container's `clientId` set and `children` populated).
      */
     val customizations: List<Customization>? = null,
+    /**
+     * Catalogue of changesets the server can produce for this session. Each
+     * entry advertises a subscribable view of file changes (uncommitted,
+     * session-wide, per-turn, etc.) and the URI template the client expands
+     * before subscribing. See {@link Changeset} for the full shape and
+     * {@link /guide/changesets | Changesets} for an overview of the model.
+     */
+    val changesets: List<Changeset>? = null,
     /**
      * Additional provider-specific metadata for this session.
      * 
@@ -984,14 +992,6 @@ data class SessionSummary(
      * The working directory URI for this session
      */
     val workingDirectory: String? = null,
-    /**
-     * Catalogue of changesets the server can produce for this session. Each
-     * entry advertises a subscribable view of file changes (uncommitted,
-     * session-wide, per-turn, etc.) and the URI template the client expands
-     * before subscribing. See {@link Changeset} for the full shape and
-     * {@link /guide/changesets | Changesets} for an overview of the model.
-     */
-    val changesets: List<Changeset>? = null,
     /**
      * Aggregate summary of file changes associated with this session. Servers
      * may populate this to give clients a quick at-a-glance view of the

diff --git a/clients/rust/CHANGELOG.md b/clients/rust/CHANGELOG.md
@@ -26,7 +26,8 @@ matching `## [X.Y.Z]` heading is missing from this file.
 
 ### Changed
 
-- Renamed the `ChangesetSummary` type to `Changeset` (catalogue entry on `SessionSummary.changesets`). The on-the-wire shape is unchanged.
+- Renamed the `ChangesetSummary` type to `Changeset`. The on-the-wire shape is unchanged.
+- Moved the `changesets` catalogue from `SessionSummary` to `SessionState`. The `session/changesetsChanged` action now updates `state.changesets` directly instead of `state.summary.changesets`.
 
 ### Removed
 

diff --git a/clients/rust/crates/ahp-types/src/actions.rs b/clients/rust/crates/ahp-types/src/actions.rs
@@ -577,8 +577,9 @@ pub struct SessionActivityChangedAction {
 
 /// The {@link Changeset | catalogue of changesets} the agent host
 /// advertises for this session changed. Replaces
-/// `state.summary.changesets` entirely (full-replacement semantics) — set
-/// to `undefined` to clear the catalogue.
+/// {@link SessionState.changesets | `state.changesets`} entirely
+/// (full-replacement semantics) — set to `undefined` to clear the
+/// catalogue.
 ///
 /// Producers dispatch this whenever entries are added or removed. The
 /// fan-out happens through this action so observers see catalogue

diff --git a/clients/rust/crates/ahp-types/src/notifications.rs b/clients/rust/crates/ahp-types/src/notifications.rs
@@ -79,8 +79,7 @@ pub struct SessionRemovedParams {
 ///   {@link SessionSummary | `SessionSummary`} changes for a session the
 ///   server has surfaced via `listSessions()` or `root/sessionAdded`.
 ///   Servers MAY coalesce or debounce updates for noisy fields (for example,
-///   `modifiedAt` bumps while a turn is streaming, or rapidly changing
-///   `changesets`) at their discretion.
+///   `modifiedAt` bumps while a turn is streaming) at their discretion.
 /// - Clients that have no cached entry for `session` MAY ignore the
 ///   notification; it is not a substitute for `root/sessionAdded`.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
@@ -218,13 +217,6 @@ pub struct PartialSessionSummary {
     /// The working directory URI for this session
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub working_directory: Option<Uri>,
-    /// Catalogue of changesets the server can produce for this session. Each
-    /// entry advertises a subscribable view of file changes (uncommitted,
-    /// session-wide, per-turn, etc.) and the URI template the client expands
-    /// before subscribing. See {@link Changeset} for the full shape and
-    /// {@link /guide/changesets | Changesets} for an overview of the model.
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub changesets: Option<Vec<Changeset>>,
     /// Aggregate summary of file changes associated with this session. Servers
     /// may populate this to give clients a quick at-a-glance view of the
     /// session's footprint (e.g., for list rendering) without requiring the

diff --git a/clients/rust/crates/ahp-types/src/state.rs b/clients/rust/crates/ahp-types/src/state.rs
@@ -716,6 +716,13 @@ pub struct SessionState {
     /// container's `clientId` set and `children` populated).
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub customizations: Option<Vec<Customization>>,
+    /// Catalogue of changesets the server can produce for this session. Each
+    /// entry advertises a subscribable view of file changes (uncommitted,
+    /// session-wide, per-turn, etc.) and the URI template the client expands
+    /// before subscribing. See {@link Changeset} for the full shape and
+    /// {@link /guide/changesets | Changesets} for an overview of the model.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub changesets: Option<Vec<Changeset>>,
     /// Additional provider-specific metadata for this session.
     ///
     /// Clients MAY look for well-known keys here to provide enhanced UI.
@@ -782,13 +789,6 @@ pub struct SessionSummary {
     /// The working directory URI for this session
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub working_directory: Option<Uri>,
-    /// Catalogue of changesets the server can produce for this session. Each
-    /// entry advertises a subscribable view of file changes (uncommitted,
-    /// session-wide, per-turn, etc.) and the URI template the client expands
-    /// before subscribing. See {@link Changeset} for the full shape and
-    /// {@link /guide/changesets | Changesets} for an overview of the model.
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub changesets: Option<Vec<Changeset>>,
     /// Aggregate summary of file changes associated with this session. Servers
     /// may populate this to give clients a quick at-a-glance view of the
     /// session's footprint (e.g., for list rendering) without requiring the

diff --git a/clients/rust/crates/ahp/src/hosts/runtime.rs b/clients/rust/crates/ahp/src/hosts/runtime.rs
@@ -720,9 +720,6 @@ fn apply_summary_changes(
     if let Some(v) = &changes.working_directory {
         existing.working_directory = Some(v.clone());
     }
-    if let Some(v) = &changes.changesets {
-        existing.changesets = Some(v.clone());
-    }
 }
 
 // ─── Random helpers (no external dep on `rand`) ─────────────────────────────

diff --git a/clients/rust/crates/ahp/src/reducers.rs b/clients/rust/crates/ahp/src/reducers.rs
@@ -619,7 +619,7 @@ pub fn apply_action_to_session(state: &mut SessionState, action: &StateAction) -
             ReduceOutcome::Applied
         }
         StateAction::SessionChangesetsChanged(a) => {
-            state.summary.changesets = a.changesets.clone();
+            state.changesets = a.changesets.clone();
             ReduceOutcome::Applied
         }
         StateAction::SessionConfigChanged(a) => {
@@ -1219,7 +1219,6 @@ mod tests {
                 model: None,
                 agent: None,
                 working_directory: None,
-                changesets: None,
                 changes: None,
             },
             lifecycle: SessionLifecycle::Creating,
@@ -1233,6 +1232,7 @@ mod tests {
             input_requests: None,
             config: None,
             customizations: None,
+            changesets: None,
             meta: None,
         }
     }

diff --git a/clients/rust/crates/ahp/tests/hosts.rs b/clients/rust/crates/ahp/tests/hosts.rs
@@ -1032,7 +1032,6 @@ fn make_summary(uri: &str, title: &str, modified_at: i64) -> ahp_types::state::S
         model: None,
         agent: None,
         working_directory: None,
-        changesets: None,
         changes: None,
     }
 }

diff --git a/clients/rust/crates/ahp/tests/multi_host_state_mirror.rs b/clients/rust/crates/ahp/tests/multi_host_state_mirror.rs
@@ -56,7 +56,6 @@ fn session_state(title: &str, resource: &str) -> SessionState {
             model: None,
             agent: None,
             working_directory: None,
-            changesets: None,
             changes: None,
         },
         lifecycle: SessionLifecycle::Ready,
@@ -70,6 +69,7 @@ fn session_state(title: &str, resource: &str) -> SessionState {
         input_requests: None,
         config: None,
         customizations: None,
+        changesets: None,
         meta: None,
     }
 }
@@ -364,7 +364,6 @@ fn non_action_event_is_ignored() {
                 model: None,
                 agent: None,
                 working_directory: None,
-                changesets: None,
                 changes: None,
             },
         }),

diff --git a/clients/swift/AHPApp/AHPApp/Store/AppStore.swift b/clients/swift/AHPApp/AHPApp/Store/AppStore.swift
@@ -1283,7 +1283,6 @@ final class AppStore {
         if let v = changes.project { summary.project = v }
         if let v = changes.model { summary.model = v }
         if let v = changes.workingDirectory { summary.workingDirectory = v }
-        if let v = changes.changesets { summary.changesets = v }
         sessionSummariesCache[uri] = summary
     }
 

diff --git a/...swift/AgentHostProtocol/Sources/AgentHostProtocol/Generated/Notifications.generated.swift b/...swift/AgentHostProtocol/Sources/AgentHostProtocol/Generated/Notifications.generated.swift
@@ -164,12 +164,6 @@ public struct PartialSessionSummary: Codable, Sendable {
     public var agent: AgentSelection?
     /// The working directory URI for this session
     public var workingDirectory: String?
-    /// Catalogue of changesets the server can produce for this session. Each
-    /// entry advertises a subscribable view of file changes (uncommitted,
-    /// session-wide, per-turn, etc.) and the URI template the client expands
-    /// before subscribing. See {@link Changeset} for the full shape and
-    /// {@link /guide/changesets | Changesets} for an overview of the model.
-    public var changesets: [Changeset]?
     /// Aggregate summary of file changes associated with this session. Servers
     /// may populate this to give clients a quick at-a-glance view of the
     /// session's footprint (e.g., for list rendering) without requiring the
@@ -188,7 +182,6 @@ public struct PartialSessionSummary: Codable, Sendable {
         model: ModelSelection? = nil,
         agent: AgentSelection? = nil,
         workingDirectory: String? = nil,
-        changesets: [Changeset]? = nil,
         changes: ChangesSummary? = nil
     ) {
         self.resource = resource
@@ -202,7 +195,6 @@ public struct PartialSessionSummary: Codable, Sendable {
         self.model = model
         self.agent = agent
         self.workingDirectory = workingDirectory
-        self.changesets = changesets
         self.changes = changes
     }
 }