From c0e823f6611b4fddaa2b724b356ae015cf1fca4c Mon Sep 17 00:00:00 2001
From: "prath.shenoy" <prath.shenoy@uber.com>
Date: Tue, 29 Sep 2026 22:16:56 +0000
Subject: [PATCH] feat(stovepipe): Persist terminal build ID

**What**:
- Record the build that completes each request with its terminal state.

**Why**:
- Preserve the winning build identity for downstream request processing.
---
 .../controller/buildsignal/buildsignal.go     | 23 ++++++++++---------
 .../buildsignal/buildsignal_test.go           |  6 ++++-
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/stovepipe/controller/buildsignal/buildsignal.go b/stovepipe/controller/buildsignal/buildsignal.go
index 2c56a04b8..fdca5a7a8 100644
--- a/stovepipe/controller/buildsignal/buildsignal.go
+++ b/stovepipe/controller/buildsignal/buildsignal.go
@@ -177,7 +177,7 @@ func (c *Controller) Process(ctx context.Context, delivery consumer.Delivery) er
 		if err := c.persistBuildFinishedLog(ctx, store, request, build.ID); err != nil {
 			return err
 		}
-		if err := c.finishRequest(ctx, store, &request, effective); err != nil {
+		if err := c.finishRequest(ctx, store, &request, build.ID, effective); err != nil {
 			return err
 		}
 		if err := c.persistOutcomeLog(ctx, store, request); err != nil {
@@ -222,9 +222,9 @@ func (c *Controller) persistBuildFinishedLog(ctx context.Context, store storage.
 }
 
 // finishRequest releases the queue's build slot and projects the build's
-// terminal status onto the request, leaving it terminal. It is a no-op when the
-// request already carries an outcome, so a redelivery neither double-releases
-// the slot nor rewrites the state.
+// terminal status and ID onto the request, leaving it terminal. It is a no-op
+// when the request already carries an outcome, so a redelivery neither
+// double-releases the slot nor rewrites the state.
 //
 // The slot is released *before* the terminal write, and a failed release aborts
 // the write, matching the DLQ reconciler (see stovepipe/controller/dlq/dlq.go).
@@ -234,7 +234,7 @@ func (c *Controller) persistBuildFinishedLog(ctx context.Context, store storage.
 // the request non-terminal, so redelivery re-runs both steps and decrements again
 // — transiently over-admitting by one until releaseBuildSlot's zero clamp
 // reconverges, which is the failure mode this pipeline prefers.
-func (c *Controller) finishRequest(ctx context.Context, store storage.Storage, request *entity.Request, status entity.BuildStatus) error {
+func (c *Controller) finishRequest(ctx context.Context, store storage.Storage, request *entity.Request, buildID string, status entity.BuildStatus) error {
 	if request.State.HasBuildOutcome() {
 		return nil
 	}
@@ -244,7 +244,7 @@ func (c *Controller) finishRequest(ctx context.Context, store storage.Storage, r
 		return err
 	}
 
-	if err := c.markOutcome(ctx, store, request, outcomeState(status)); err != nil {
+	if err := c.markOutcome(ctx, store, request, buildID, outcomeState(status)); err != nil {
 		metrics.NamedCounter(c.metricsScope, _opName, "storage_errors", 1, metrics.TagsFromContext(ctx)...)
 		return err
 	}
@@ -286,11 +286,11 @@ func outcomeState(status entity.BuildStatus) entity.RequestState {
 	}
 }
 
-// markOutcome CAS-transitions request from processing to state, retrying on version
-// conflicts. First writer wins: once any outcome is recorded a later caller leaves it
-// alone, so duplicate builds for one request (which build.md accepts) cannot flip the
-// verdict back and forth.
-func (c *Controller) markOutcome(ctx context.Context, store storage.Storage, request *entity.Request, state entity.RequestState) error {
+// markOutcome CAS-transitions request from processing to state, recording the
+// winning build ID and retrying on version conflicts. First writer wins: once
+// any outcome is recorded a later caller leaves it alone, so duplicate builds
+// for one request (which build.md accepts) cannot flip the verdict back and forth.
+func (c *Controller) markOutcome(ctx context.Context, store storage.Storage, request *entity.Request, buildID string, state entity.RequestState) error {
 	reqStore := store.GetRequestStore()
 
 	for {
@@ -300,6 +300,7 @@ func (c *Controller) markOutcome(ctx context.Context, store storage.Storage, req
 
 		updated := *request
 		updated.State = state
+		updated.TerminalBuildID = buildID
 		newVersion := request.Version + 1
 		if err := reqStore.Update(ctx, updated, request.Version, newVersion); err != nil {
 			if errors.Is(err, storage.ErrVersionMismatch) {
diff --git a/stovepipe/controller/buildsignal/buildsignal_test.go b/stovepipe/controller/buildsignal/buildsignal_test.go
index 0bfb76820..c52d56596 100644
--- a/stovepipe/controller/buildsignal/buildsignal_test.go
+++ b/stovepipe/controller/buildsignal/buildsignal_test.go
@@ -147,12 +147,16 @@ func buildSignalPayload(t *testing.T, id string) []byte {
 
 // requestWithState returns a Request past process's admit, in the given state.
 func requestWithState(state entity.RequestState) entity.Request {
-	return entity.Request{
+	request := entity.Request{
 		ID:      testID,
 		Queue:   testQueue,
 		State:   state,
 		Version: 1,
 	}
+	if state.HasBuildOutcome() {
+		request.TerminalBuildID = testBuildID
+	}
+	return request
 }
 
 // build returns a Build with the given status/version, tied to testID.