diff --git a/modules/mesh-build-go/cmd/mesh-build-go/fetch.go b/modules/mesh-build-go/cmd/mesh-build-go/fetch.go
index f612dbb5..e9d2f57f 100644
--- a/modules/mesh-build-go/cmd/mesh-build-go/fetch.go
+++ b/modules/mesh-build-go/cmd/mesh-build-go/fetch.go
@@ -42,11 +42,13 @@ type FetchResult struct {
 	// head onto it, the paths the merge changes, and the tree of each module directory (a directory holding a
 	// module.json) in the merge. A head that does not merge cleanly is an answer: Merge is empty, Conflicts names the
 	// files, and the workspace is left at the trunk commit.
-	Base      string                          `json:"base,omitempty"`
-	Merge     string                          `json:"merge,omitempty"`
-	Conflicts []string                        `json:"conflicts,omitempty"`
-	Changed   []string                        `json:"changed,omitempty"`
-	Trees     map[string]buildstep.ModuleTree `json:"trees,omitempty"`
+	Base      string   `json:"base,omitempty"`
+	Merge     string   `json:"merge,omitempty"`
+	Conflicts []string `json:"conflicts,omitempty"`
+	Changed   []string `json:"changed,omitempty"`
+	// Programs are the changed files that are compiled programs (issue 1577); a merge answers it, a pointer to an empty list when there are none, absent for a fetch that made no merge.
+	Programs *[]buildstep.Program            `json:"programs,omitempty"`
+	Trees    map[string]buildstep.ModuleTree `json:"trees,omitempty"`
 	// Beside are the sibling repositories placed as plain directories under the workspace's beside directory, which
 	// build_go_test hands to the tests as MESH_CHECK_BESIDE (ADR 0484 clause 4).
 	Beside []Sibling `json:"beside,omitempty"`
diff --git a/modules/mesh-build-go/cmd/mesh-build-go/preview.go b/modules/mesh-build-go/cmd/mesh-build-go/preview.go
index 067dcfff..1636678e 100644
--- a/modules/mesh-build-go/cmd/mesh-build-go/preview.go
+++ b/modules/mesh-build-go/cmd/mesh-build-go/preview.go
@@ -41,6 +41,9 @@ func (m *Module) merge(ctx context.Context, res *FetchResult, tree, remote, base
 	}
 	res.Base = mr.Base
 	res.Conflicts, res.Merge, res.Changed = mr.Conflicts, mr.Merge, mr.Changed
+	if mr.Merge != "" {
+		res.Programs = &mr.Programs
+	}
 	if res.Merge == "" {
 		return nil
 	}
diff --git a/modules/mesh-build-go/cmd/mesh-build-go/preview_test.go b/modules/mesh-build-go/cmd/mesh-build-go/preview_test.go
index 55877c84..6df51b81 100644
--- a/modules/mesh-build-go/cmd/mesh-build-go/preview_test.go
+++ b/modules/mesh-build-go/cmd/mesh-build-go/preview_test.go
@@ -77,7 +77,7 @@ func TestFetchWithABaseMergesAndAnswersThePreview(t *testing.T) {
 		t.Fatal(err)
 	}
 	if res.Base != baseSHA || res.Merge != mergeSHA || res.Commit != commitSHA || len(res.Conflicts) != 0 ||
-		strings.Join(res.Changed, ",") != "a.go,modules/m/main.go" {
+		strings.Join(res.Changed, ",") != "a.go,modules/m/main.go" || res.Programs == nil || len(*res.Programs) != 0 { // 1577: a merge says it found no program
 		t.Errorf("result = %s", st.Result)
 	}
 	mt, ok := res.Trees["modules/m"]
diff --git a/modules/mesh-build-go/go.mod b/modules/mesh-build-go/go.mod
index 868b22d2..60c998fe 100644
--- a/modules/mesh-build-go/go.mod
+++ b/modules/mesh-build-go/go.mod
@@ -3,7 +3,7 @@ module meshbuildgo
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026142629-ff81bdf8cc8f
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026175935-22bc4dc8ef4f
 	github.com/distribution/distribution/v3 v3.1.2
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
diff --git a/modules/mesh-build-go/go.sum b/modules/mesh-build-go/go.sum
index c86aa01f..eaa82453 100644
--- a/modules/mesh-build-go/go.sum
+++ b/modules/mesh-build-go/go.sum
@@ -1,5 +1,7 @@
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026142629-ff81bdf8cc8f h1:GYLCvz2x+JNUOTbXzyh2QwzX0sTzvRlXR7lGocWjk3A=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026142629-ff81bdf8cc8f/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026175935-22bc4dc8ef4f h1:LwefZSIEVjhdhgx22kgL+eJFfD9VVGJblYNPUCh1yZQ=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026175935-22bc4dc8ef4f/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/alicebob/miniredis/v2 v2.35.0 h1:QwLphYqCEAo1eu1TqPRN2jgVMPBweeQcR21jeqDCONI=
 github.com/alicebob/miniredis/v2 v2.35.0/go.mod h1:TcL7YfarKPGDAthEtl5NBeHZfeUQj6OXMm/+iu5cLMM=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
diff --git a/modules/mesh-build-image/cmd/mesh-build-image/fetch.go b/modules/mesh-build-image/cmd/mesh-build-image/fetch.go
index e07bbfda..b139be23 100644
--- a/modules/mesh-build-image/cmd/mesh-build-image/fetch.go
+++ b/modules/mesh-build-image/cmd/mesh-build-image/fetch.go
@@ -31,13 +31,15 @@ const ForgeAlias = "mesh-forge"
 // files in conflict, the paths the merge changes and the tree of each module directory). A head that does not
 // merge cleanly is an answer: Merge is empty, Conflicts names the files, and the workspace is left at the trunk.
 type FetchResult struct {
-	Workspace string                          `json:"workspace"`
-	Commit    string                          `json:"commit"`
-	Base      string                          `json:"base,omitempty"`
-	Merge     string                          `json:"merge,omitempty"`
-	Conflicts []string                        `json:"conflicts,omitempty"`
-	Changed   []string                        `json:"changed,omitempty"`
-	Trees     map[string]buildstep.ModuleTree `json:"trees,omitempty"`
+	Workspace string   `json:"workspace"`
+	Commit    string   `json:"commit"`
+	Base      string   `json:"base,omitempty"`
+	Merge     string   `json:"merge,omitempty"`
+	Conflicts []string `json:"conflicts,omitempty"`
+	Changed   []string `json:"changed,omitempty"`
+	// Programs are the changed files that are compiled programs (issue 1577); a merge answers it, a pointer to an empty list when there are none, absent for a fetch that made no merge.
+	Programs *[]buildstep.Program            `json:"programs,omitempty"`
+	Trees    map[string]buildstep.ModuleTree `json:"trees,omitempty"`
 }
 
 func (m *Module) fetchTool() StepTool {
@@ -127,6 +129,9 @@ func (m *Module) merge(ctx context.Context, res *FetchResult, tree, remote, base
 	}
 	res.Base = mr.Base
 	res.Conflicts, res.Merge, res.Changed = mr.Conflicts, mr.Merge, mr.Changed
+	if mr.Merge != "" {
+		res.Programs = &mr.Programs
+	}
 	if res.Merge == "" {
 		return nil
 	}
diff --git a/modules/mesh-build-image/go.mod b/modules/mesh-build-image/go.mod
index 52658707..c384556e 100644
--- a/modules/mesh-build-image/go.mod
+++ b/modules/mesh-build-image/go.mod
@@ -3,7 +3,7 @@ module meshbuildimage
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026142629-ff81bdf8cc8f
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026175935-22bc4dc8ef4f
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 )
diff --git a/modules/mesh-build-image/go.sum b/modules/mesh-build-image/go.sum
index ba65afa3..8efd6402 100644
--- a/modules/mesh-build-image/go.sum
+++ b/modules/mesh-build-image/go.sum
@@ -1,5 +1,7 @@
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026142629-ff81bdf8cc8f h1:GYLCvz2x+JNUOTbXzyh2QwzX0sTzvRlXR7lGocWjk3A=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026142629-ff81bdf8cc8f/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026175935-22bc4dc8ef4f h1:LwefZSIEVjhdhgx22kgL+eJFfD9VVGJblYNPUCh1yZQ=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026175935-22bc4dc8ef4f/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=
diff --git a/modules/mesh-build-node/cmd/mesh-build-node/fetch.go b/modules/mesh-build-node/cmd/mesh-build-node/fetch.go
index 5f712e16..31307a46 100644
--- a/modules/mesh-build-node/cmd/mesh-build-node/fetch.go
+++ b/modules/mesh-build-node/cmd/mesh-build-node/fetch.go
@@ -51,11 +51,13 @@ type FetchResult struct {
 	// commit, the merge commit of the head onto it, the paths the merge changes and the tree of each module directory.
 	// A head that does not merge cleanly is an answer: Merge is empty, Conflicts names the files, and the workspace is
 	// left at the trunk commit with nothing installed.
-	Base      string                          `json:"base,omitempty"`
-	Merge     string                          `json:"merge,omitempty"`
-	Conflicts []string                        `json:"conflicts,omitempty"`
-	Changed   []string                        `json:"changed,omitempty"`
-	Trees     map[string]buildstep.ModuleTree `json:"trees,omitempty"`
+	Base      string   `json:"base,omitempty"`
+	Merge     string   `json:"merge,omitempty"`
+	Conflicts []string `json:"conflicts,omitempty"`
+	Changed   []string `json:"changed,omitempty"`
+	// Programs are the changed files that are compiled programs (issue 1577); a merge answers it, a pointer to an empty list when there are none, absent for a fetch that made no merge.
+	Programs *[]buildstep.Program            `json:"programs,omitempty"`
+	Trees    map[string]buildstep.ModuleTree `json:"trees,omitempty"`
 	// Group is the group's package the fetch packed and served to the TypeScript members (the call's `package`):
 	// "<name>@<version> <integrity>".
 	Group string `json:"group,omitempty"`
diff --git a/modules/mesh-build-node/cmd/mesh-build-node/preview.go b/modules/mesh-build-node/cmd/mesh-build-node/preview.go
index 6d641b9b..48011ed7 100644
--- a/modules/mesh-build-node/cmd/mesh-build-node/preview.go
+++ b/modules/mesh-build-node/cmd/mesh-build-node/preview.go
@@ -27,6 +27,9 @@ func (m *Module) merge(ctx context.Context, run forgekey.Runner, res *FetchResul
 	}
 	res.Base = mr.Base
 	res.Conflicts, res.Merge, res.Changed = mr.Conflicts, mr.Merge, mr.Changed
+	if mr.Merge != "" {
+		res.Programs = &mr.Programs
+	}
 	if res.Merge == "" {
 		return nil
 	}
diff --git a/modules/mesh-build-node/go.mod b/modules/mesh-build-node/go.mod
index e79f663b..f0e1bfe5 100644
--- a/modules/mesh-build-node/go.mod
+++ b/modules/mesh-build-node/go.mod
@@ -3,7 +3,7 @@ module meshbuildnode
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026142629-ff81bdf8cc8f
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026175935-22bc4dc8ef4f
 	github.com/distribution/distribution/v3 v3.1.2
 	github.com/nats-io/nats.go v1.54.0
 )
diff --git a/modules/mesh-build-node/go.sum b/modules/mesh-build-node/go.sum
index 28122ac9..b6238d01 100644
--- a/modules/mesh-build-node/go.sum
+++ b/modules/mesh-build-node/go.sum
@@ -1,5 +1,7 @@
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026142629-ff81bdf8cc8f h1:GYLCvz2x+JNUOTbXzyh2QwzX0sTzvRlXR7lGocWjk3A=
 git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026142629-ff81bdf8cc8f/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026175935-22bc4dc8ef4f h1:LwefZSIEVjhdhgx22kgL+eJFfD9VVGJblYNPUCh1yZQ=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261026175935-22bc4dc8ef4f/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/alicebob/miniredis/v2 v2.35.0 h1:QwLphYqCEAo1eu1TqPRN2jgVMPBweeQcR21jeqDCONI=
 github.com/alicebob/miniredis/v2 v2.35.0/go.mod h1:TcL7YfarKPGDAthEtl5NBeHZfeUQj6OXMm/+iu5cLMM=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=