refactor(web): publish transient model request capacity (round 1)

packages/client/runtime/src/client/sessions/conversation.ts

@@ -12,6 +12,15 @@ import type { PendingInteraction } from './pending.ts'
 
 export type { TodoItem }
 
+/**
+ * Durable Host metrics with the latest capacity observed on this live mux
+ * connection overlaid for presentation.
+ */
+export interface ConversationMetrics extends SessionMetrics {
+  /** Latest dispatched-request capacity; absent until observed or after reset/clear. */
+  contextWindow?: number
+}
+
 /** Assistant content blocks sorted by what the UI cares about
  *  (text body / collapsible reasoning / tool-call card head / other fallback). */
 export type AssistantBlock =
@@ -247,9 +256,9 @@ export interface ConversationSnapshot {
    *  write (last write wins); empty = the log holds no plan. */
   todos: readonly TodoItem[]
   /**
-   * Host-owned cumulative usage and current-context projection. Independent
-   * of `nodes` pagination; null until a tail response or live metrics frame
-   * supplies a current value.
+   * Host-owned cumulative usage/current pressure with live mux-local capacity
+   * overlaid. Independent of `nodes` pagination; null until a tail response or
+   * live metrics frame supplies a current durable value.
    */
-  metrics: SessionMetrics | null
+  metrics: ConversationMetrics | null
 }

packages/client/runtime/src/client/sessions/session.ts

@@ -12,7 +12,7 @@ import type {
 import { transportError } from '@deepseek-ai/dsh-host-apiproxy/api'
 import type { ObservableSnapshot } from '../contract/store.ts'
 import type {
-  CodeSubCall, ComposerPhase, ConversationNode, ConversationSnapshot, OpenState,
+  CodeSubCall, ComposerPhase, ConversationMetrics, ConversationNode, ConversationSnapshot, OpenState,
   PromptError, QueuedMessage, RunningToolCall,
 } from './conversation.ts'
 import type { PendingInteraction } from './pending.ts'
@@ -102,8 +102,10 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
   /** Current whole-list todo/write projection: each tail history response replaces it (an omitted
    *  field is the authoritative empty list) and every live write overwrites it. */
   private todos: readonly TodoItem[] = []
-  /** Host-owned metrics projection; ordering resets on each subscribed baseline. */
-  private metrics: SessionMetrics | null = null
+  /** Host-owned metrics with current-connection request capacity overlaid. */
+  private metrics: ConversationMetrics | null = null
+  /** Latest capacity observed on this mux connection, independent of durable metrics arrival. */
+  private contextWindow: number | undefined
   /** `run_code` sub-dispatches by parent callId (window-derived, like openCalls). Appends
    *  copy-on-write the per-parent array so published snapshot references never mutate. */
   private codeDispatches = new Map<string, readonly CodeSubCall[]>()
@@ -367,6 +369,7 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
           this.queueRev++
           this.notifier.markDirty()
         }
+        this.contextWindow = undefined
         if (this.metrics !== null) {
           this.metrics = null
           this.notifier.markDirty()
@@ -377,6 +380,18 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
         this.installMetrics(frame.metrics)
         return
       }
+      case 'session/model-request': {
+        if (this.contextWindow === frame.contextWindow) return
+        this.contextWindow = frame.contextWindow
+        if (this.metrics !== null) {
+          const { contextWindow: _previous, ...durable } = this.metrics
+          this.metrics = frame.contextWindow === undefined
+            ? durable
+            : { ...durable, contextWindow: frame.contextWindow }
+          this.notifier.markDirty()
+        }
+        return
+      }
       case 'approval/requested': {
         const { type: _type, sessionId: _sid, ...payload } = frame
         this.mint(new PendingWait('approval', rpcId, this.sessionId, payload, m => this.api.respond(m)))
@@ -800,7 +815,9 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
         || metrics.projectionRevision < current.projectionRevision
       )
     ) return
-    this.metrics = metrics
+    this.metrics = this.contextWindow === undefined
+      ? metrics
+      : { ...metrics, contextWindow: this.contextWindow }
     this.notifier.markDirty()
   }