feat(tools): live dispatch lifecycle + native-contract parallel sub-calls in Code Mode

The bridge replaces its serialization queue with a pool that reuses the
native concurrency contract: submissions classify through
registry.executionMode (fail-closed isConcurrencySafe), start strictly in
submission order, overlap up to the validated maxParallelSubCalls config
(default 10; 1 restores serial), and exclusive calls drain the pool, run
alone, and bar later calls. Each started sub-call logs a
tool/code-dispatch-start event at pool entry; the existing
tool/code-dispatch settles the pair (started ⇔ settles exactly once;
abandoned queued calls log neither). SDK prompt guidance now states the
true Promise.all contract — re-recorded across every code/both-mode
snapshot (plus the stale cordis-dynamic-toolchain fixture gaining the
required description arg).

Client: CodeSubCall widens to RunningToolCall | ToolResultNode — starts
land the running shape (rows wear the native running ring), settles
replace in place preserving start order, callTime pairs to the start
time. Fixture emits start/settle pairs; jsdom pins the running sub-row;
runtime specs pin in-place settlement and out-of-order completion.

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

@@ -128,15 +128,19 @@ export type ConversationNode =
   | UnknownSurfaceNode
 
 /**
- * One `run_code` sub-dispatch materialized as a {@link ToolResultNode} so every
- * consumer (tool rows, details panel) renders it through the exact components
- * that render a native settled call. Never part of the surface `nodes` flow —
- * sub-calls live under their parent via {@link ConversationSnapshot.codeDispatches}.
- * `callId` is the deterministic sub-call id (`<parent>:code:<n>`); `call`
- * carries the sub-tool name and its JSON-stringified logged arguments;
- * `content`/`isError` are the sub-call's complete logged outcome.
+ * One `run_code` sub-dispatch materialized in the native call-block shapes so
+ * every consumer (tool rows, details panel) renders it through the exact
+ * components that render a native call: a started-but-unsettled sub-call is a
+ * {@link RunningToolCall} (rows derive the running state from the shape,
+ * exactly as for native calls) and its `tool/code-dispatch` settlement
+ * replaces it in place with the {@link ToolResultNode} form. Never part of
+ * the surface `nodes` flow — sub-calls live under their parent via
+ * {@link ConversationSnapshot.codeDispatches}. `callId` is the deterministic
+ * sub-call id (`<parent>:code:<n>`); the call side carries the sub-tool name
+ * and its JSON-stringified logged arguments; `content`/`isError` are the
+ * settled sub-call's complete logged outcome.
  */
-export type CodeSubCall = ToolResultNode
+export type CodeSubCall = RunningToolCall | ToolResultNode
 
 /** In-flight tool card material: tool/call seen, tool/result not yet. */
 export interface RunningToolCall {

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

@@ -616,14 +616,36 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
   /** Per-event side effects (right column of the §A.9 dispatch table):
    *  chunk accumulation / partial clear on finalize / openCalls add-remove. */
   private applyEventSideEffects(event: SessionEvent, view?: ToolEventView): void {
-    // `tool/code-dispatch` is declared by the host-side dsh-tools plugin whose
-    // types cannot enter the client program (its host Context merges collide
-    // with the client's), so this wire consumer narrows it structurally —
-    // the same posture as every other cross-wire event payload.
+    // The `tool/code-dispatch-start`/`tool/code-dispatch` pair is declared by
+    // the host-side dsh-tools plugin whose types cannot enter the client
+    // program (its host Context merges collide with the client's), so this
+    // wire consumer narrows them structurally — the same posture as every
+    // other cross-wire event payload.
+    if ((event.type as string) === 'tool/code-dispatch-start') {
+      // A started sub-dispatch enters the index as a RunningToolCall — the
+      // exact shape a native in-flight call renders from — under its parent
+      // run_code callId; it never joins the surface flow.
+      const data = event.data as unknown as {
+        parentCallId: string
+        subCallId: string
+        name: string
+        arguments: unknown
+      }
+      const running: CodeSubCall = {
+        callId: data.subCallId, name: data.name,
+        argsRaw: JSON.stringify(data.arguments),
+        turn: 0, step: 0, time: event.time, callView: null,
+      }
+      const siblings = this.codeDispatches.get(data.parentCallId) ?? []
+      this.codeDispatches.set(data.parentCallId, [...siblings, running])
+      this.dispatchesRev++
+      return
+    }
     if ((event.type as string) === 'tool/code-dispatch') {
-      // A sub-dispatch becomes a ToolResultNode so rows and the details
-      // panel reuse the native rendering path verbatim; it indexes under its
-      // parent run_code callId and never joins the surface flow.
+      // Settlement replaces the running entry in place (same array position,
+      // so parallel sub-calls keep their start order) with the
+      // ToolResultNode form; a settle with no observed start (history window
+      // cut mid-pair, or a pre-start-event log) appends directly.
       const data = event.data as unknown as {
         parentCallId: string
         subCallId: string
@@ -632,17 +654,22 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
         isError: boolean
         content: ContentBlock[]
       }
-      const parent = data.parentCallId
-      const siblings = this.codeDispatches.get(parent) ?? []
-      const sub: CodeSubCall = {
+      const siblings = this.codeDispatches.get(data.parentCallId) ?? []
+      const at = siblings.findIndex(sub => sub.callId === data.subCallId)
+      const started = at === -1 ? undefined : siblings[at]
+      const settled: CodeSubCall = {
         kind: 'tool-result', seq: event.seq, time: event.time,
         callId: data.subCallId,
         call: { name: data.name, argsRaw: JSON.stringify(data.arguments) },
-        callTime: event.time,
+        // Duration source: the paired start's time when observed.
+        callTime: started === undefined ? event.time : started.time,
         content: data.content, isError: data.isError,
         callView: null, resultView: null,
       }
-      this.codeDispatches.set(parent, [...siblings, sub])
+      this.codeDispatches.set(
+        data.parentCallId,
+        at === -1 ? [...siblings, settled] : siblings.map((sub, index) => (index === at ? settled : sub)),
+      )
       this.dispatchesRev++
       return
     }