feat(automation): surface structured-region body steps in run observability (#1505) (#1580)

loop / parallel / try_catch ran their body, branch and handler regions against
a region-local step log that was discarded, so listRuns/getRun showed the
container as a single opaque step. runRegion() now RETURNS its body steps and the
container folds them into the parent run log via a new NodeExecutionResult.childSteps
field, appended right after the container's own step.

Each surfaced step is tagged with its immediate container via three new optional
fields on ExecutionStepLogSchema (and the engine's StepLogEntry):
- parentNodeId: enclosing loop/parallel/try_catch node
- iteration: zero-based loop iteration or parallel branch index
- regionKind: loop-body | parallel-branch | try | catch

Tagging fills only undefined fields, so nested regions keep each step's innermost
container. Failed try-attempt partial steps stay unsurfaced (preserves try_catch
retry semantics). Fully additive. +4 tests across loop/parallel/try_catch.

Resolves the ADR-0031 #1505 / TODO(#1479) follow-up.

Co-authored-by: Jack Zhuang <277994282+os-zhuang@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: 3 people

.changeset/region-step-logs.md

@@ -0,0 +1,25 @@
+---
+'@objectstack/spec': patch
+'@objectstack/service-automation': patch
+---
+
+feat(automation): surface structured-region body steps in run observability (#1505)
+
+`loop` / `parallel` / `try_catch` previously ran their body, branch, and handler
+regions against a region-local step log that was **discarded** — run logs
+(`listRuns` / `getRun`) showed the container as a single opaque step, hiding the
+per-iteration / per-branch steps that actually executed.
+
+`AutomationEngine.runRegion()` now **returns** its body steps, and the container
+node folds them into the parent run log via a new `NodeExecutionResult.childSteps`
+field. Each surfaced step is tagged with its **immediate** container via three new
+optional fields on `ExecutionStepLogSchema` (and the engine's `StepLogEntry`):
+
+- `parentNodeId` — the enclosing `loop` / `parallel` / `try_catch` node
+- `iteration` — zero-based loop iteration or parallel branch index
+- `regionKind` — `loop-body` | `parallel-branch` | `try` | `catch`
+
+Tagging fills only fields left undefined, so nested regions keep each step's
+innermost container. A failed try-region attempt's partial steps are still not
+surfaced (preserving `try_catch` retry semantics). Fully additive — existing run
+logs and consumers are unaffected.

docs/adr/0031-advanced-flow-node-executors-and-dag.md

@@ -1,6 +1,6 @@
 # ADR-0031: Structured control-flow for flows (loop / parallel / try-catch) — native + AI-authored, BPMN as interop
 
-**Status**: Accepted (2026-06-02) — implemented in #1482 (spec + loop), #1489 (parallel), #1499 (try/catch/retry), #1500 (BPMN mapping); docs #1497. Follow-ups: #1504 (BPMN XML plugin), #1505 (region step logs).
+**Status**: Accepted (2026-06-02) — implemented in #1482 (spec + loop), #1489 (parallel), #1499 (try/catch/retry), #1500 (BPMN mapping); docs #1497. Follow-ups: #1504 (BPMN XML plugin); ~~#1505 (region step logs)~~ **done** — `runRegion` now returns its body steps and the container folds them into the run log via `NodeExecutionResult.childSteps`, tagged with `parentNodeId` / `iteration` / `regionKind` (`ExecutionStepLogSchema`).
 **Deciders**: ObjectStack Protocol Architects
 **Builds on**: [ADR-0018](./0018-unified-node-action-registry.md) (open action registry — node types are an open vocabulary, executors are the source of truth), [ADR-0019](./0019-approval-as-flow-node.md) (durable-pause node via suspend/resume), [ADR-0010](./0010-nl-to-flow-authoring.md) + [ADR-0011](./0011-actions-as-ai-tools.md) (AI flow authoring — **the design center**)
 **Consumers**: `@objectstack/services/service-automation` (engine + builtin executors), `@objectstack/spec` (`automation/flow.zod.ts`, `automation/bpmn-interop.zod.ts`, `studio/flow-builder.zod.ts`), `../objectui` (flow designer)

packages/services/service-automation/src/builtin/loop-node.test.ts

@@ -92,6 +92,34 @@ describe('loop container executor (ADR-0031)', () => {
     ]);
   });
 
+  it('surfaces each iteration\'s body steps in the run log, tagged with parentNodeId + index (#1479)', async () => {
+    engine.registerFlow('loop_flow', loopFlow(
+      {
+        collection: '{items}',
+        iteratorVariable: 'item',
+        indexVariable: 'i',
+        body: { nodes: [{ id: 'b', type: 'collect', label: 'Body', config: { itemVar: 'item', idxVar: 'i' } }], edges: [] },
+      },
+      { items: ['a', 'b', 'c'] },
+    ));
+
+    await engine.execute('loop_flow');
+    const runs = await engine.listRuns('loop_flow');
+    const bodySteps = runs[0].steps.filter(s => s.nodeId === 'b');
+
+    // One body step per iteration, each tagged with the loop container + index.
+    expect(bodySteps).toHaveLength(3);
+    expect(bodySteps.map(s => s.iteration)).toEqual([0, 1, 2]);
+    expect(bodySteps.every(s => s.parentNodeId === 'loop')).toBe(true);
+    expect(bodySteps.every(s => s.regionKind === 'loop-body')).toBe(true);
+
+    // The container step and the after-loop step stay un-grouped (top level).
+    const loopStep = runs[0].steps.find(s => s.nodeId === 'loop');
+    const afterStep = runs[0].steps.find(s => s.nodeId === 'after');
+    expect(loopStep?.parentNodeId).toBeUndefined();
+    expect(afterStep?.parentNodeId).toBeUndefined();
+  });
+
   it('runs a multi-node body region in order each iteration', async () => {
     engine.registerFlow('loop_flow', loopFlow(
       {

packages/services/service-automation/src/builtin/loop-node.ts

@@ -4,7 +4,7 @@ import type { PluginContext } from '@objectstack/core';
 import { defineActionDescriptor, LOOP_MAX_ITERATIONS_CEILING } from '@objectstack/spec/automation';
 import type { FlowRegionParsed } from '@objectstack/spec/automation';
 import type { AutomationContext } from '@objectstack/spec/contracts';
-import type { AutomationEngine } from '../engine.js';
+import type { AutomationEngine, StepLogEntry } from '../engine.js';
 import { interpolate } from './template.js';
 
 /**
@@ -110,15 +110,22 @@ export function registerLoopNode(engine: AutomationEngine, ctx: PluginContext):
       }
 
       let iterations = 0;
+      const childSteps: StepLogEntry[] = [];
       for (let i = 0; i < collection.length; i++) {
         variables.set(iteratorVariable, collection[i]);
         if (indexVariable) variables.set(indexVariable, i);
         // Body runs in the shared scope; iterator var + mutations are visible.
-        await engine.runRegion(body, variables, context ?? ({} as AutomationContext));
+        // #1479: collect each iteration's body steps, tagged with the index.
+        const iterSteps = await engine.runRegion(body, variables, context ?? ({} as AutomationContext), {
+          parentNodeId: node.id,
+          iteration: i,
+          regionKind: 'loop-body',
+        });
+        childSteps.push(...iterSteps);
         iterations++;
       }
 
-      return { success: true, output: { iterations } };
+      return { success: true, output: { iterations }, childSteps };
     },
   });
 

packages/services/service-automation/src/builtin/parallel-node.test.ts

@@ -84,6 +84,25 @@ describe('parallel block executor (ADR-0031)', () => {
     expect(order.filter(o => o === 'after')).toHaveLength(1);
   });
 
+  it('surfaces each branch\'s steps in the run log, tagged with parentNodeId + branch index (#1479)', async () => {
+    engine.registerFlow('par_flow', parallelFlow([
+      { name: 'A', nodes: [{ id: 'a', type: 'setvar', label: 'A', config: { key: 'a', value: 1 } }], edges: [] },
+      { name: 'B', nodes: [{ id: 'b', type: 'setvar', label: 'B', config: { key: 'b', value: 2 } }], edges: [] },
+    ]));
+
+    await engine.execute('par_flow');
+    const runs = await engine.listRuns('par_flow');
+
+    const stepA = runs[0].steps.find(s => s.nodeId === 'a');
+    const stepB = runs[0].steps.find(s => s.nodeId === 'b');
+    expect(stepA?.parentNodeId).toBe('par');
+    expect(stepA?.iteration).toBe(0);
+    expect(stepA?.regionKind).toBe('parallel-branch');
+    expect(stepB?.parentNodeId).toBe('par');
+    expect(stepB?.iteration).toBe(1);
+    expect(stepB?.regionKind).toBe('parallel-branch');
+  });
+
   it('joins only after the slowest branch completes', async () => {
     // Branch "slow" awaits several microtasks; "fast" resolves immediately.
     // The join ('after') must still be last.

packages/services/service-automation/src/builtin/parallel-node.ts

@@ -4,7 +4,7 @@ import type { PluginContext } from '@objectstack/core';
 import { defineActionDescriptor } from '@objectstack/spec/automation';
 import type { FlowRegionParsed } from '@objectstack/spec/automation';
 import type { AutomationContext } from '@objectstack/spec/contracts';
-import type { AutomationEngine } from '../engine.js';
+import type { AutomationEngine, StepLogEntry } from '../engine.js';
 
 /** One branch of a parallel block — a region plus an optional label. */
 interface ParallelBranch extends FlowRegionParsed {
@@ -75,17 +75,25 @@ export function registerParallelNode(engine: AutomationEngine, ctx: PluginContex
         };
       }
 
+      let branchSteps: StepLogEntry[][];
       try {
         // Implicit join: continue once when ALL branches have completed.
-        await Promise.all(
-          branches.map(branch => engine.runRegion(branch, variables, context ?? ({} as AutomationContext))),
+        // #1479: each branch returns its body steps, tagged with the branch index.
+        branchSteps = await Promise.all(
+          branches.map((branch, i) =>
+            engine.runRegion(branch, variables, context ?? ({} as AutomationContext), {
+              parentNodeId: node.id,
+              iteration: i,
+              regionKind: 'parallel-branch',
+            }),
+          ),
         );
       } catch (err) {
         const message = err instanceof Error ? err.message : String(err);
         return { success: false, error: `parallel '${node.id}': branch failed — ${message}` };
       }
 
-      return { success: true, output: { branches: branches.length } };
+      return { success: true, output: { branches: branches.length }, childSteps: branchSteps.flat() };
     },
   });
 

packages/services/service-automation/src/builtin/try-catch-node.test.ts

@@ -98,6 +98,31 @@ describe('try/catch/retry executor (ADR-0031)', () => {
     expect(ran[ran.length - 1]).toBe('after'); // downstream continued after catch
   });
 
+  it('surfaces the try region steps tagged regionKind=try (#1479)', async () => {
+    engine.registerFlow('tc_flow', tcFlow({
+      try: { nodes: [{ id: 't', type: 'ok', label: 'T', config: { tag: 'try' } }], edges: [] },
+    }));
+
+    await engine.execute('tc_flow');
+    const runs = await engine.listRuns('tc_flow');
+    const tryStep = runs[0].steps.find(s => s.nodeId === 't');
+    expect(tryStep?.parentNodeId).toBe('tc');
+    expect(tryStep?.regionKind).toBe('try');
+  });
+
+  it('surfaces the catch region steps tagged regionKind=catch when the try fails (#1479)', async () => {
+    engine.registerFlow('tc_flow', tcFlow({
+      try: { nodes: [{ id: 't', type: 'boom', label: 'T' }], edges: [] },
+      catch: { nodes: [{ id: 'c', type: 'handler', label: 'C' }], edges: [] },
+    }));
+
+    await engine.execute('tc_flow');
+    const runs = await engine.listRuns('tc_flow');
+    const catchStep = runs[0].steps.find(s => s.nodeId === 'c');
+    expect(catchStep?.parentNodeId).toBe('tc');
+    expect(catchStep?.regionKind).toBe('catch');
+  });
+
   it('retries the try region with backoff and succeeds without running catch', async () => {
     engine.registerFlow('tc_flow', tcFlow({
       try: { nodes: [{ id: 't', type: 'flaky', label: 'T', config: { failTimes: 2 } }], edges: [] },

packages/services/service-automation/src/builtin/try-catch-node.ts

@@ -104,8 +104,12 @@ export function registerTryCatchNode(engine: AutomationEngine, ctx: PluginContex
           if (delay > 0) await new Promise(r => setTimeout(r, delay));
         }
         try {
-          await engine.runRegion(tryRegion, variables, ctxOrEmpty);
-          return { success: true, output: { attempts: attempt + 1, caught: false } };
+          // #1479: surface the successful try region's steps.
+          const trySteps = await engine.runRegion(tryRegion, variables, ctxOrEmpty, {
+            parentNodeId: node.id,
+            regionKind: 'try',
+          });
+          return { success: true, output: { attempts: attempt + 1, caught: false }, childSteps: trySteps };
         } catch (err) {
           lastError = err instanceof Error ? err.message : String(err);
         }
@@ -115,8 +119,16 @@ export function registerTryCatchNode(engine: AutomationEngine, ctx: PluginContex
       if (catchRegion != null) {
         variables.set(errorVariable, { nodeId: node.id, message: lastError });
         try {
-          await engine.runRegion(catchRegion, variables, ctxOrEmpty);
-          return { success: true, output: { attempts: maxRetries + 1, caught: true, error: lastError } };
+          // #1479: surface the catch handler region's steps.
+          const catchSteps = await engine.runRegion(catchRegion, variables, ctxOrEmpty, {
+            parentNodeId: node.id,
+            regionKind: 'catch',
+          });
+          return {
+            success: true,
+            output: { attempts: maxRetries + 1, caught: true, error: lastError },
+            childSteps: catchSteps,
+          };
         } catch (catchErr) {
           const catchMsg = catchErr instanceof Error ? catchErr.message : String(catchErr);
           return { success: false, error: `try_catch '${node.id}': catch region failed — ${catchMsg}` };

packages/services/service-automation/src/engine.ts

@@ -76,6 +76,14 @@ export interface NodeExecutionResult {
      * the form and `resume()` with the values.
      */
     screen?: ScreenSpec;
+    /**
+     * #1479: step logs produced inside the node's structured region(s). A
+     * container node (`loop` / `parallel` / `try_catch`) collects the
+     * {@link AutomationEngine.runRegion} return value(s) here; {@link AutomationEngine.executeNode}
+     * appends them to the parent run log right after the container's own step,
+     * so per-iteration / per-branch body steps surface in run observability.
+     */
+    childSteps?: StepLogEntry[];
 }
 
 // ─── Trigger Interface (Plugin Extension Point) ─────────────────────
@@ -202,6 +210,18 @@ export interface StepLogEntry {
     completedAt?: string;
     durationMs?: number;
     error?: { code: string; message: string; stack?: string };
+    /**
+     * #1479: structured-region grouping. When a step ran inside a `loop` /
+     * `parallel` / `try_catch` body region, these tag it with its **immediate**
+     * container so run observability can distinguish per-iteration / per-branch
+     * body steps from top-level ones. Set by {@link AutomationEngine.runRegion}
+     * (innermost wins — never overwritten as steps bubble through nested regions).
+     */
+    parentNodeId?: string;
+    /** Zero-based loop iteration or parallel branch index of the enclosing region. */
+    iteration?: number;
+    /** Which region kind the step ran in: `loop-body` | `parallel-branch` | `try` | `catch`. */
+    regionKind?: string;
 }
 
 /**
@@ -1471,6 +1491,12 @@ export class AutomationEngine implements IAutomationService {
                 durationMs: Date.now() - stepStart,
             });
 
+            // #1479: fold a structured-region container's body/branch/handler
+            // steps into the run log, right after the container's own step.
+            if (result.childSteps?.length) {
+                steps.push(...result.childSteps);
+            }
+
             // Write back output variables
             if (result.output) {
                 for (const [key, value] of Object.entries(result.output)) {
@@ -1564,8 +1590,13 @@ export class AutomationEngine implements IAutomationService {
      * nodes/edges, so the main DAG traversal (`traverseNext`) is never aware of
      * scope markers — keeping the shared traversal untouched.
      *
-     * Body step logs are kept in a region-local array (not yet merged into the
-     * parent run log); surfacing per-iteration steps is a follow-up.
+     * #1479: the executed body steps are **returned** (tagged with `grouping`)
+     * so the calling container node can fold them into the parent run log via
+     * `NodeExecutionResult.childSteps`. Tagging only fills fields left undefined,
+     * so when regions nest, each step keeps its **innermost** container's
+     * `parentNodeId` / `iteration` / `regionKind`. On failure the region throws
+     * as before (preserving `try_catch` retry semantics); a failed attempt's
+     * partial steps are not surfaced.
      *
      * Durable pause (`suspend`) inside a region is not supported in this
      * iteration — it is converted into a clear error (mirrors the `subflow`
@@ -1575,16 +1606,15 @@ export class AutomationEngine implements IAutomationService {
         region: FlowRegionParsed,
         variables: Map<string, unknown>,
         context: AutomationContext,
-    ): Promise<void> {
+        grouping?: { parentNodeId: string; iteration?: number; regionKind?: string },
+    ): Promise<StepLogEntry[]> {
         const entryId = findRegionEntry(region);
         const entry = region.nodes.find(n => n.id === entryId);
         if (!entry) {
             throw new Error(`region entry node '${entryId}' not found`);
         }
         // A synthetic flow view — executeNode/traverseNext only read `nodes`/`edges`.
         const subFlow = { nodes: region.nodes, edges: region.edges ?? [] } as unknown as FlowParsed;
-        // TODO(#1479): merge region step logs into the parent run log so
-        // per-iteration body steps surface in run observability.
         const regionSteps: StepLogEntry[] = [];
         try {
             await this.executeNode(entry, subFlow, variables, context, regionSteps);
@@ -1596,6 +1626,19 @@ export class AutomationEngine implements IAutomationService {
             }
             throw err;
         }
+        // Tag this region's steps with their immediate container. Innermost wins:
+        // a step that already carries a `parentNodeId` (set by a nested region)
+        // is left untouched.
+        if (grouping) {
+            for (const step of regionSteps) {
+                if (step.parentNodeId === undefined) {
+                    step.parentNodeId = grouping.parentNodeId;
+                    if (grouping.iteration !== undefined) step.iteration = grouping.iteration;
+                    if (grouping.regionKind !== undefined) step.regionKind = grouping.regionKind;
+                }
+            }
+        }
+        return regionSteps;
     }
 
     /**

packages/spec/src/automation/execution.zod.ts

@@ -58,6 +58,13 @@ export const ExecutionStepLogSchema = lazySchema(() => z.object({
     stack: z.string().optional().describe('Stack trace'),
   }).optional().describe('Error details if step failed'),
   retryAttempt: z.number().int().min(0).optional().describe('Retry attempt number (0 = first try)'),
+  // #1479: structured-region grouping. Tag a step that ran inside a
+  // `loop` / `parallel` / `try_catch` body region with its immediate container,
+  // so run observability can nest per-iteration / per-branch body steps under
+  // the container instead of showing it as a single opaque step.
+  parentNodeId: z.string().optional().describe('Enclosing structured-region container node ID (loop/parallel/try_catch)'),
+  iteration: z.number().int().min(0).optional().describe('Zero-based loop iteration or parallel branch index of the enclosing region'),
+  regionKind: z.string().optional().describe('Region kind the step ran in: loop-body | parallel-branch | try | catch'),
 }));
 export type ExecutionStepLog = z.infer<typeof ExecutionStepLogSchema>;