From 23fe0d46ad0d81843e30c2346cc7285223e9a074 Mon Sep 17 00:00:00 2001
From: Jeff Musgrave <1578618+JeffMusgrave@users.noreply.github.com>
Date: Tue, 20 Oct 2026 03:32:19 -0400
Subject: [PATCH] Compile governed Cargo replacements through their consumers

Prepare 0.29.4. Real-Cargo regression checks preserve the consumer lock, reject replacement type errors, avoid dependency development targets, and keep the Rust/Go check execution aligned with its plan. The Rust module suite and new quality regression pass; broader verification is in progress.
---
 CHANGELOG.md                                  |  7 +++
 VERSION                                       |  2 +-
 docs/design/cargo-facts.md                    | 14 +++++-
 internal/quality/cargo_test.go                | 26 ++++++++++
 internal/rustfacts/compilation.go             |  4 +-
 .../rustfacts/compilation_patches_test.go     | 49 +++++++++++++++++++
 internal/rustfacts/discovery.go               |  5 ++
 7 files changed, 103 insertions(+), 4 deletions(-)
 create mode 100644 internal/rustfacts/compilation_patches_test.go

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 75c637c8..53eb918d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,13 @@
 
 ## Unreleased
 
+## 0.29.4 - 2026-10-20
+
+- Compile governed Cargo replacements through their actual consumer, including
+  when only replacement source is selected. Retain source discovery and checks
+  without requiring dependency-owned locks or compiling dependency development
+  targets. Keep mixed Rust/Go execution aligned with the gate's command plan.
+
 ## 0.29.3 - 2026-10-18
 
 - Resolve cyclic Rust glob exports and root `extern crate` aliases without
diff --git a/VERSION b/VERSION
index 5540b6e0..35b1b3d1 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.29.3
+0.29.4
diff --git a/docs/design/cargo-facts.md b/docs/design/cargo-facts.md
index 7e64dd03..90d4c7f3 100644
--- a/docs/design/cargo-facts.md
+++ b/docs/design/cargo-facts.md
@@ -290,8 +290,18 @@ invitation for the check to resolve dependencies.
 
 Checks select the manifest's ordinary Cargo packages, default features and all
 enabled targets, using the governed native host explicitly. They do not enable
-every feature or establish coverage of other target configurations. Compiler
-warnings, Clippy's default lint group and unused-code lints use `--force-warn` at
+every feature or establish coverage of other target configurations.
+
+Compiler selection maps explicitly governed replacement packages to their consumers,
+using the same ownership boundary as locked resolution. Discovery retains the
+replacement's own metadata for source analysis and also discovers its consumer.
+Selecting only replacement source still checks the consumer; selecting both
+does not compile it twice. Replacement development targets and their independent
+locks are not part of the consumer build. Source analysis remains selected for
+the replacement, while compiler evidence covers only dependencies active in the
+consumer's default feature and host configuration.
+
+Compiler warnings, Clippy's default lint group and unused-code lints use `--force-warn` at
 the invocation boundary. Source `allow`, `expect`, `deny` and `forbid` attributes
 cannot hide these diagnostics or turn policy lint collection into a compiler
 failure. Code Polishy treats the resulting typed findings as blocking errors,
diff --git a/internal/quality/cargo_test.go b/internal/quality/cargo_test.go
index 0a1feda5..6533e7e7 100644
--- a/internal/quality/cargo_test.go
+++ b/internal/quality/cargo_test.go
@@ -80,6 +80,32 @@ func TestCargoAndGoCheckPlanMatchesObservedCommandOrder(t *testing.T) {
 	}
 }
 
+func TestCargoReplacementCheckKeepsGoCommandsInsideThePlan(t *testing.T) {
+	t.Parallel()
+	repo := cargoQualityRepository(t)
+	repo.Config.SupplyChain.DependencyOverridePolicies = []policy.DependencyOverridePolicy{{Ecosystem: "cargo", Path: "Cargo.toml", Field: "patch.crates-io"}}
+	writeQualityFile(t, repo.Root, "Cargo.toml", "[package]\nname='app'\nversion='1.0.0'\nedition='2024'\n[workspace]\nexclude=['vendor/library']\n[dependencies]\nlibrary='=1.0.0'\n[patch.crates-io]\nlibrary={path='vendor/library'}\n")
+	writeQualityFile(t, repo.Root, "Cargo.lock", "version=4\n[[package]]\nname='app'\nversion='1.0.0'\ndependencies=['library']\n[[package]]\nname='library'\nversion='1.0.0'\n")
+	writeQualityFile(t, repo.Root, "src/lib.rs", "pub fn app() {\n    library::call();\n}\n")
+	writeQualityFile(t, repo.Root, "vendor/library/Cargo.toml", "[package]\nname='library'\nversion='1.0.0'\nedition='2024'\n")
+	writeQualityFile(t, repo.Root, "vendor/library/src/lib.rs", "pub fn call() {}\n")
+	writeQualityFile(t, repo.Root, "go.mod", "module example.test/mixed\n\ngo 1.26.6\n")
+	writeQualityFile(t, repo.Root, "main.go", "package main\n\nfunc main() {}\n")
+	selection := repository.Selection{Files: []string{"main.go", "src/lib.rs", "vendor/library/src/lib.rs"}}
+	planned := CheckCommands(repo, selection, "check")
+	boundary := &cargoRecordingRunner{OSRunner: runner.OSRunner{}}
+	if findings := Check(t.Context(), repo, selection, boundary, "check"); len(findings) != 0 {
+		t.Fatalf("replacement prevented the mixed-language check: %+v", findings)
+	}
+	want := []string{}
+	for _, command := range planned {
+		want = append(want, command.Name)
+	}
+	if !reflect.DeepEqual(boundary.names, want) {
+		t.Fatalf("executed commands = %v, planned = %v", boundary.names, want)
+	}
+}
+
 func TestCargoNativeDeadCodePreservesPublicAPIAndChecksSelectedFeatures(t *testing.T) {
 	t.Parallel()
 	repo := cargoQualityRepository(t)
diff --git a/internal/rustfacts/compilation.go b/internal/rustfacts/compilation.go
index 1a3a43df..8d35f743 100644
--- a/internal/rustfacts/compilation.go
+++ b/internal/rustfacts/compilation.go
@@ -26,7 +26,9 @@ func PlanCompilation(repo repository.Repository, discovery DiscoveryPlan, allFil
 	if len(discovery.Commands) == 0 {
 		return plan
 	}
-	for _, manifest := range discovery.Manifests {
+	manifests, _, findings := cargoResolutionRoots(repo, discovery.Manifests)
+	plan.Findings = append(plan.Findings, findings...)
+	for _, manifest := range manifests {
 		files := compilationSources(repo, manifest, allFiles)
 		native, err := repo.NativeUnit(files, "lint", "typecheck", "dead-code")
 		if err != nil {
diff --git a/internal/rustfacts/compilation_patches_test.go b/internal/rustfacts/compilation_patches_test.go
new file mode 100644
index 00000000..b5608b05
--- /dev/null
+++ b/internal/rustfacts/compilation_patches_test.go
@@ -0,0 +1,49 @@
+package rustfacts
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"slices"
+	"testing"
+
+	"github.com/riteofstring/code-polishy/internal/policy"
+	"github.com/riteofstring/code-polishy/internal/runner"
+)
+
+func TestRustCompilationUsesReplacementConsumerAndPreservesDependencyTargets(t *testing.T) {
+	t.Parallel()
+	for _, selected := range []string{"Cargo.toml", "vendor/patch-source/src/lib.rs", "vendor/leaf/src/lib.rs"} {
+		t.Run(selected, func(t *testing.T) {
+			repo := cargoPatchRepository(t)
+			manifest := string(readRustFile(t, repo, "Cargo.toml"))
+			manifest = string(bytes.ReplaceAll([]byte(manifest), []byte("default=[]"), []byte("default=['desktop']")))
+			write(t, repo.Root, "Cargo.toml", manifest)
+			write(t, repo.Root, "src/lib.rs", "pub fn value() -> u32 { patch_source::value() }\n")
+			write(t, repo.Root, "vendor/patch-source/src/lib.rs", "pub fn value() -> u32 { patch_leaf::value() }\n")
+			write(t, repo.Root, "vendor/patch-source/build.rs", "fn main() {}\n")
+			write(t, repo.Root, "vendor/patch-source/tests/unconsumed.rs", "compile_error!(\"dependency development targets must not compile\");\n")
+			write(t, repo.Root, "vendor/leaf/src/lib.rs", "pub fn value() -> u32 { 42 }\n")
+			before := readRustFile(t, repo, "Cargo.lock")
+			plan, discovery := compilationDiscovery(t, repo, selected)
+			if findings := Compile(t.Context(), repo, plan, discovery, runner.OSRunner{}); len(findings) != 0 {
+				t.Fatalf("consumer compilation failed: %+v", findings)
+			}
+			if !bytes.Equal(before, readRustFile(t, repo, "Cargo.lock")) {
+				t.Fatal("compilation changed the consumer lock")
+			}
+			for _, path := range []string{"vendor/patch-source/Cargo.lock", "vendor/leaf/Cargo.lock"} {
+				if _, err := os.Stat(filepath.Join(repo.Root, filepath.FromSlash(path))); !os.IsNotExist(err) {
+					t.Fatalf("compilation created a replacement lock at %s: %v", path, err)
+				}
+			}
+			write(t, repo.Root, "vendor/leaf/src/lib.rs", "pub fn value() -> u32 { \"wrong\" }\n")
+			findings := Compile(t.Context(), repo, plan, discovery, runner.OSRunner{})
+			if !slices.ContainsFunc(findings, func(f policy.Finding) bool {
+				return f.Check == "quality.rustCompiler" && f.Subject == "E0308" && f.Path == "vendor/leaf/src/lib.rs"
+			}) {
+				t.Fatalf("consumer failed to check the replacement source: %+v", findings)
+			}
+		})
+	}
+}
diff --git a/internal/rustfacts/discovery.go b/internal/rustfacts/discovery.go
index 11997ec5..e2426dda 100644
--- a/internal/rustfacts/discovery.go
+++ b/internal/rustfacts/discovery.go
@@ -29,6 +29,11 @@ func PlanDiscovery(repo repository.Repository, selected, allFiles []string) Disc
 	if len(manifests) == 0 {
 		return plan
 	}
+	consumers, _, findings := cargoResolutionRoots(repo, manifests)
+	plan.Findings = append(plan.Findings, findings...)
+	manifests = append(manifests, consumers...)
+	slices.Sort(manifests)
+	manifests = slices.Compact(manifests)
 	if err := configurationProblem(repo); err != nil {
 		plan.Findings = append(plan.Findings, projectFinding(manifests[0], "configuration", err.Error()))
 		return plan