feat(web): project plan mode through host API

packages/host/apiproxy/src/api/index.ts

@@ -19,7 +19,7 @@ export interface ApiProxy {
 }
 
 // ---- Domain interfaces and payload entities ----
-export type { HistoryEntry, SessionsApi, SessionSummary } from './sessions.ts'
+export type { HistoryEntry, PlanModeState, SessionsApi, SessionSummary } from './sessions.ts'
 export type { HostApi } from './host.ts'
 export type { EventsApi, MuxFrame, HostFrame, ToolCallView, ToolEventView, ToolResultView } from './events.ts'
 export type { ApprovalResponsePayload } from './approvals.ts'

packages/host/apiproxy/src/api/rpc-map.ts

@@ -15,6 +15,8 @@ export interface RpcMethodMap {
   'session.history': SessionsApi['history']
   'session.prompt': SessionsApi['prompt']
   'session.cancel': SessionsApi['cancel']
+  'session.planMode': SessionsApi['planMode']
+  'session.setPlanMode': SessionsApi['setPlanMode']
   'host.describe': HostApi['describe']
 }
 

packages/host/apiproxy/src/api/sessions.schema.ts

@@ -9,7 +9,7 @@ import { z } from 'zod'
 import type { SessionEvent, SessionId } from '@deepseek-ai/dsh-session/types'
 import type { RequestPayload, ResponseValue } from './rpc-map.ts'
 import type { Wire } from './rpc.schema.ts'
-import type { HistoryEntry, SessionSummary } from './sessions.ts'
+import type { HistoryEntry, PlanModeState, SessionSummary } from './sessions.ts'
 import type { ToolEventView } from './events.ts'
 
 /** SessionId: one brand cast after shape validation (the only cast point in this domain). */
@@ -108,3 +108,28 @@ export const sessionCancelRequestSchema = z.object({
 export const sessionCancelValueSchema = z.object({
   accepted: z.literal(true),
 }) satisfies z.ZodType<Wire<ResponseValue<'session.cancel'>>>
+
+/** Plan state shared by the read and selection responses. */
+export const planModeStateSchema = z.object({
+  active: z.boolean(),
+  pending: z.boolean().optional(),
+}) satisfies z.ZodType<Wire<PlanModeState>>
+
+/** session.planMode request payload. */
+export const sessionPlanModeRequestSchema = z.object({
+  sessionId: sessionIdSchema,
+}) satisfies z.ZodType<Wire<RequestPayload<'session.planMode'>>>
+
+/** session.planMode response value; null means the optional service is absent. */
+export const sessionPlanModeValueSchema =
+  planModeStateSchema.nullable() satisfies z.ZodType<Wire<ResponseValue<'session.planMode'>>>
+
+/** session.setPlanMode request payload. */
+export const sessionSetPlanModeRequestSchema = z.object({
+  sessionId: sessionIdSchema,
+  active: z.boolean(),
+}) satisfies z.ZodType<Wire<RequestPayload<'session.setPlanMode'>>>
+
+/** session.setPlanMode response value; null means the optional service is absent. */
+export const sessionSetPlanModeValueSchema =
+  planModeStateSchema.nullable() satisfies z.ZodType<Wire<ResponseValue<'session.setPlanMode'>>>

packages/host/apiproxy/src/api/sessions.ts

@@ -44,6 +44,16 @@ export interface SessionSummary {
   cwd?: string
 }
 
+/**
+ * Plan collaboration state exposed to clients. `active` is the logged state
+ * shaping the current request; `pending`, when present, is the user's
+ * next-boundary selection.
+ */
+export interface PlanModeState {
+  active: boolean
+  pending?: boolean
+}
+
 /** Session-domain unary methods (the map keys session.* of RpcMethodMap). */
 export interface SessionsApi {
   /** Lists persisted sessions (updatedAt descending). v1 returns everything; cursor is a reserved seat, unimplemented. */
@@ -70,4 +80,18 @@ export interface SessionsApi {
 
   /** Stops: clears both FIFOs + aborts the current step (1:1 with agent.cancel). */
   cancel(request: RpcRequest<{ sessionId: SessionId }>): Promise<RpcResponse<{ accepted: true }>>
+
+  /**
+   * Reads plan collaboration state. `null` means the host did not compose the
+   * optional plan-mode service; it is distinct from inactive state.
+   */
+  planMode(request: RpcRequest<{ sessionId: SessionId }>): Promise<RpcResponse<PlanModeState | null>>
+
+  /**
+   * Selects plan collaboration state for the next model-request boundary.
+   * The returned state exposes the still-committed value and pending target;
+   * `null` means plan mode is unavailable on this host.
+   */
+  setPlanMode(request: RpcRequest<{ sessionId: SessionId; active: boolean }>):
+  Promise<RpcResponse<PlanModeState | null>>
 }