Qualify auto-generated sub-orchestration IDs across continue_as_new generations

docs/replay-engine-test-spec.md

@@ -253,7 +253,8 @@ Tests for deterministic child instance ID.
 
 | Test | Baseline | Handler | Expected |
 |------|----------|---------|----------|
-| `auto_instance_id` | `[Started]` | `schedule_sub_orchestration("Child", input)` | Instance = `sub::{event_id}` |
+| `auto_instance_id` | `[Started]` | `schedule_sub_orchestration("Child", input)` | Instance = `sub::{event_id}` (execution 1) |
+| `auto_instance_id_includes_execution_id_for_later_generations` | `[Started(execution=2)]` | `schedule_sub_orchestration("Child", input)` | Instance = `sub::2.{event_id}` |
 | `explicit_instance_preserved` | `[Started]` | `schedule_sub_orchestration_with_instance("my-id", ...)` | Instance = "my-id" |
 | `replay_uses_history_instance` | `[Started, SubOrchScheduled{instance:"sub::2"}]` | Same schedule | Binds to same instance |
 

docs/sub-orchestrations.md

@@ -57,8 +57,8 @@ There are two modes for child instance ID assignment:
 
 **Auto-generated (default):**
 - Use `schedule_sub_orchestration()` - no instance ID parameter
-- Runtime generates `instance = "sub::{event_id}"` and prefixes with parent: `"{parent_instance}::sub::{id}"`
-- This guarantees the same child id on replays and prevents collisions across parents
+- Runtime generates `instance = "sub::{event_id}"` for execution 1, and `instance = "sub::{execution_id}.{event_id}"` for later continue-as-new executions; then prefixes with parent.
+- This guarantees the same child id on replays and prevents collisions across parents and continue-as-new generations.
 
 **Explicit:**
 - Use `schedule_sub_orchestration_with_id("Child", "my-instance-id", input)`
@@ -162,4 +162,3 @@ let root = |ctx: OrchestrationContext, input: String| async move {
 - Provider-backed durable completion routing (enqueue `SubOrchCompleted/Failed` items), leasing, DLQ.
 - Visualization: render sub-orchestration edges in Mermaid diagrams under each parent.
 
-

src/lib.rs

@@ -862,7 +862,9 @@ pub const INITIAL_EVENT_ID: u64 = 1;
 pub const SUB_ORCH_AUTO_PREFIX: &str = "sub::";
 
 /// Prefix for placeholder instance IDs before event ID assignment.
-/// These are replaced with `sub::{event_id}` during action processing.
+/// These are replaced during action processing:
+/// - execution 1: `sub::{event_id}`
+/// - execution N>1: `sub::{execution_id}.{event_id}`
 pub(crate) const SUB_ORCH_PENDING_PREFIX: &str = "sub::pending_";
 
 /// Determine if a sub-orchestration instance ID is auto-generated (needs parent prefix).

src/runtime/replay_engine.rs

@@ -1082,7 +1082,7 @@ impl ReplayEngine {
 
             ctx.bind_token(token, event_id);
 
-            let updated_action = update_action_event_id(action, event_id);
+            let updated_action = update_action_event_id(action, event_id, self.execution_id);
 
             if let crate::Action::StartSubOrchestration { instance, .. } = &updated_action {
                 ctx.bind_sub_orchestration_instance(token, instance.clone());
@@ -1750,7 +1750,7 @@ fn action_to_event(action: &Action, instance: &str, execution_id: u64, event_id:
 /// Update an action's scheduling_event_id to the correct event_id.
 /// Also generates the actual sub-orchestration instance ID from the event_id
 /// (unless an explicit instance ID was provided, indicated by not starting with SUB_ORCH_PENDING_PREFIX).
-fn update_action_event_id(action: Action, event_id: u64) -> Action {
+fn update_action_event_id(action: Action, event_id: u64, execution_id: u64) -> Action {
     match action {
         Action::CallActivity {
             name,
@@ -1793,7 +1793,11 @@ fn update_action_event_id(action: Action, event_id: u64) -> Action {
             // If instance starts with the pending prefix, it's a placeholder that needs to be replaced.
             // Otherwise, it's an explicit instance ID provided by the user.
             let final_instance = if instance.starts_with(crate::SUB_ORCH_PENDING_PREFIX) {
-                format!("{}{event_id}", crate::SUB_ORCH_AUTO_PREFIX)
+                if execution_id == crate::INITIAL_EXECUTION_ID {
+                    format!("{}{event_id}", crate::SUB_ORCH_AUTO_PREFIX)
+                } else {
+                    format!("{}{execution_id}.{event_id}", crate::SUB_ORCH_AUTO_PREFIX)
+                }
             } else {
                 instance
             };

tests/replay_engine/sub_orchestration.rs

@@ -8,6 +8,7 @@
 use super::helpers::*;
 use async_trait::async_trait;
 use duroxide::{OrchestrationContext, OrchestrationHandler};
+use duroxide::runtime::replay_engine::ReplayEngine;
 use std::sync::Arc;
 
 /// Auto-generated instance ID should be sub::{event_id}.
@@ -43,6 +44,30 @@ fn auto_instance_id() {
     }
 }
 
+/// Auto-generated instance ID includes execution_id after continue-as-new generations.
+#[test]
+fn auto_instance_id_includes_execution_id_for_later_generations() {
+    let mut started = started_event(1); // OrchestrationStarted
+    started.execution_id = 2;
+    let history = vec![started];
+    let mut engine = ReplayEngine::new(TEST_INSTANCE.to_string(), 2, history);
+    let result = execute(&mut engine, SubOrchHandler::new("Child", "child-input"));
+
+    assert_continue(&result);
+
+    assert_eq!(engine.pending_actions().len(), 1);
+    match &engine.pending_actions()[0] {
+        duroxide::Action::StartSubOrchestration {
+            instance,
+            scheduling_event_id,
+            ..
+        } => {
+            assert_eq!(instance, &format!("sub::2.{scheduling_event_id}"));
+        }
+        _ => panic!("Expected StartSubOrchestration action"),
+    }
+}
+
 /// Replay uses history's instance ID.
 ///
 /// Orchestration code: