feat(client): render user skill invocations as dedicated transcript cards

A user/message carrying the skill-invocation source materializes as its
own conversation node (name/args lifted off the source metadata, never
re-parsed from the body) and renders as a right-aligned bubble: the /name
chip plus the user's trailing text, with the injected <skill_content>
collapsed behind a disclosure. A record with an unreadable name degrades
to the injected-context row.

packages/client/runtime/src/client/index.ts

@@ -49,7 +49,7 @@ export type {
   AssistantBlock, AssistantMessageNode, AssistantProvenanceView, AssistantRequestConfig,
   AssistantTiming, CodeSubCall, CommandNode, CompactionSummaryNode, ComposerPhase,
   ContextMessageNode, ConversationNode, ConversationSnapshot, ModelRetryNode, QueuedMessage,
-  RunningToolCall,
+  RunningToolCall, SkillInvocationNode,
   SteeringMessageNode, TodoItem, ToolResultNode, TurnErrorNode, UnknownSurfaceNode, UserMessageNode,
 } from './sessions/conversation.ts'
 export type {

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

@@ -129,6 +129,25 @@ export interface ContextMessageNode {
   form: KnownContextForm | null
 }
 
+/**
+ * A user-explicit skill invocation: the host injected the rendered skill as a
+ * user message carrying the `skill-invocation` source, so the card presents
+ * `/name args` from source metadata and collapses the injected body.
+ */
+export interface SkillInvocationNode {
+  kind: 'skill-invocation'
+  seq: number
+  /** Unix epoch ms from the source session event. */
+  time: number
+  /** Invoked skill name read off the message source. */
+  name: string
+  /** Trailing user text read off the message source, when recorded. */
+  args?: string
+  /** Full injected model-facing content (collapsed by default in the UI). */
+  content: readonly ContentBlock[]
+  source: unknown
+}
+
 /** Durable notice that a closed failed step is waiting for a model-request retry. */
 export type ModelRetryNode = LlmRetryEventData & {
   kind: 'model-retry'
@@ -245,6 +264,7 @@ export type ConversationNode =
   | AssistantMessageNode
   | SteeringMessageNode
   | ContextMessageNode
+  | SkillInvocationNode
   | ModelRetryNode
   | TurnErrorNode
   | ToolResultNode

packages/client/runtime/src/client/sessions/transcript-adapter.ts

@@ -57,7 +57,20 @@ function materializeNode(
   stepTimings: ReadonlyMap<string, AssistantStepMetadata>,
 ): ConversationNode {
   switch (event.type) {
-    case 'user/message':
+    case 'user/message': {
+      // A user-explicit skill invocation carries its name (and optional args)
+      // on the source; the dedicated node lets the card render `/name args`
+      // from metadata instead of re-parsing the injected body. A record whose
+      // name is unreadable degrades to injected context below.
+      const source = event.data.source as { kind?: unknown; name?: unknown; args?: unknown }
+      if (source.kind === 'skill-invocation' && typeof source.name === 'string') {
+        return {
+          kind: 'skill-invocation', seq: event.seq, time: event.time,
+          name: source.name,
+          ...typeof source.args === 'string' ? { args: source.args } : {},
+          content: event.data.content, source: event.data.source,
+        }
+      }
       // Injected context (plugin/goal source) folds to a context node, not a
       // user message; only a direct human prompt is a user node. A compaction
       // checkpoint never reaches here (isCompactCheckpoint routes it away).
@@ -80,6 +93,7 @@ function materializeNode(
         kind: 'user', seq: event.seq, time: event.time,
         content: event.data.content, source: event.data.source,
       }
+    }
     case 'assistant/message':
       return {
         kind: 'assistant', seq: event.seq, time: event.time,