Validate derived candidate tags before checks

docs/roadmap/implementation.md

@@ -280,7 +280,9 @@ consumption uses an owned cache.
 
 ## Stage 6: Reject invalid derived candidate tags before validation
 
-**Status:** pending.
+**Status:** complete. Git and candidate package tests and public invalid-tag
+and publication regressions pass offline; malformed derived tags stop before
+Go validation and callbacks while retaining candidate identity.
 
 **Files:** `internal/git/remote.go` and its current tag-helper callers/tests,
 `internal/candidate/check.go`, public candidate tests, and candidate guidance

internal/candidate/check.go

@@ -105,6 +105,9 @@ func Capture(ctx context.Context, request Request) (Candidate, error) {
 	if err := validateNote(note, request.Product, request.Version); err != nil {
 		return captured, fmt.Errorf("release note %q: %w", identity.NotePath, err)
 	}
+	if err := git.CheckTagRef(ctx, repositoryDir, identity.Tag); err != nil {
+		return captured, fmt.Errorf("validate local candidate tag: %w", err)
+	}
 	if exists, err := hasLocalTag(ctx, repositoryDir, identity.Tag); err != nil {
 		return captured, fmt.Errorf("inspect local tag %q: %w", identity.Tag, err)
 	} else if exists {

internal/git/prepare.go

@@ -9,7 +9,7 @@ import (
 // PrepareTaggedCheckout fetches one explicit tag ref, checks its peeled commit
 // against expectedCommit, and checks out that commit detached.
 func PrepareTaggedCheckout(ctx context.Context, repositoryDir, tag, remote, expectedCommit string) error {
-	if err := checkTagRef(ctx, repositoryDir, tag); err != nil {
+	if err := CheckTagRef(ctx, repositoryDir, tag); err != nil {
 		return err
 	}
 	if !validObjectID(expectedCommit) {
@@ -35,7 +35,7 @@ func PrepareTaggedCheckout(ctx context.Context, repositoryDir, tag, remote, expe
 // VerifyTaggedCheckout confirms that the existing local tag, HEAD, and clean
 // worktree all identify the expected commit. It does not fetch or check out.
 func VerifyTaggedCheckout(ctx context.Context, repositoryDir, tag, expectedCommit string) error {
-	if err := checkTagRef(ctx, repositoryDir, tag); err != nil {
+	if err := CheckTagRef(ctx, repositoryDir, tag); err != nil {
 		return err
 	}
 	if !validObjectID(expectedCommit) {

internal/git/remote.go

@@ -100,7 +100,7 @@ func (endpoint Endpoint) Recheck(ctx context.Context, repositoryDir string) erro
 // Query reads exact main and tag refs. A command failure is unreadable,
 // never evidence that a ref is absent.
 func (endpoint Endpoint) Query(ctx context.Context, repositoryDir, tag string) (Snapshot, error) {
-	if err := checkTagRef(ctx, repositoryDir, tag); err != nil {
+	if err := CheckTagRef(ctx, repositoryDir, tag); err != nil {
 		return Snapshot{}, err
 	}
 	mainRef := "refs/heads/main"
@@ -301,7 +301,8 @@ func finalizeRef(ref RemoteRef) RemoteRef {
 	return ref
 }
 
-func checkTagRef(ctx context.Context, repositoryDir, tag string) error {
+// CheckTagRef validates a complete tag name using Git ref rules.
+func CheckTagRef(ctx context.Context, repositoryDir, tag string) error {
 	if tag == "" {
 		return fmt.Errorf("invalid Git tag name %q", tag)
 	}

internal/git/source.go

@@ -151,7 +151,7 @@ func CaptureHead(ctx context.Context, repositoryDir string) (string, error) {
 // InspectTaggedSource reads the local HEAD, worktree state, and selected tag.
 // Both lightweight historical tags and annotated tags are supported.
 func InspectTaggedSource(ctx context.Context, repositoryDir, tag string) (TaggedSource, error) {
-	if err := checkTagRef(ctx, repositoryDir, tag); err != nil {
+	if err := CheckTagRef(ctx, repositoryDir, tag); err != nil {
 		return TaggedSource{}, err
 	}
 	var source TaggedSource

internal/git/source_test.go

@@ -35,8 +35,8 @@ func TestInspectTaggedSourceSupportsLightweightAndAnnotatedTags(t *testing.T) {
 func TestTagOperationsAcceptFullSlashContainingRefs(t *testing.T) {
 	fixture := newRemoteFixture(t)
 	tag := "integrations/check/v2.3.4"
-	if err := checkTagRef(context.Background(), fixture.work, tag); err != nil {
+	if err := CheckTagRef(context.Background(), fixture.work, tag); err != nil {
-		t.Fatalf("checkTagRef(%q): %v", tag, err)
+		t.Fatalf("CheckTagRef(%q): %v", tag, err)
 	}
 	object, err := CreateAnnotatedTag(context.Background(), fixture.work, tag, fixture.commit, []byte("release note\n"))
 	if err != nil {
@@ -57,8 +57,8 @@ func TestTagOperationsAcceptFullSlashContainingRefs(t *testing.T) {
 func TestTagReferenceValidationUsesGitRules(t *testing.T) {
 	fixture := newRemoteFixture(t)
 	for _, tag := range []string{"", "v1..2.3", "v1.2.3.lock", "v1.2.3/", "v1.2.3\\bad"} {
-		if err := checkTagRef(context.Background(), fixture.work, tag); err == nil {
+		if err := CheckTagRef(context.Background(), fixture.work, tag); err == nil {
-			t.Errorf("checkTagRef(%q) succeeded", tag)
+			t.Errorf("CheckTagRef(%q) succeeded", tag)
 		}
 	}
 }

internal/git/tag.go

@@ -11,7 +11,7 @@ import (
 // CreateAnnotatedTag records the captured note as an unsigned annotated tag
 // on the captured commit and returns the tag object's ID.
 func CreateAnnotatedTag(ctx context.Context, repositoryDir, tag, commit string, note []byte) (string, error) {
-	if err := checkTagRef(ctx, repositoryDir, tag); err != nil {
+	if err := CheckTagRef(ctx, repositoryDir, tag); err != nil {
 		return "", err
 	}
 	if !validObjectID(commit) {
@@ -71,7 +71,7 @@ func CreateAnnotatedTag(ctx context.Context, repositoryDir, tag, commit string,
 // InspectLocalTag confirms the selected tag still points to the exact
 // annotated tag object captured before publication.
 func InspectLocalTag(ctx context.Context, repositoryDir, tag, expectedObject string) error {
-	if err := checkTagRef(ctx, repositoryDir, tag); err != nil {
+	if err := CheckTagRef(ctx, repositoryDir, tag); err != nil {
 		return err
 	}
 	if !validObjectID(expectedObject) {
@@ -99,7 +99,7 @@ func InspectLocalTag(ctx context.Context, repositoryDir, tag, expectedObject str
 // one exact authoritative version tag and its peeled commit. Failed
 // verification or reads are unreadable and never interpreted as absence.
 func (endpoint Endpoint) QueryTag(ctx context.Context, repositoryDir, tag string) (RemoteRef, error) {
-	if err := checkTagRef(ctx, repositoryDir, tag); err != nil {
+	if err := CheckTagRef(ctx, repositoryDir, tag); err != nil {
 		return RemoteRef{}, err
 	}
 	if err := endpoint.verifyScopedURLs(ctx, repositoryDir); err != nil {
@@ -129,7 +129,7 @@ func (endpoint Endpoint) QueryTag(ctx context.Context, repositoryDir, tag string
 
 // PushTag publishes only the captured tag object to its exact tag ref.
 func (endpoint Endpoint) PushTag(ctx context.Context, repositoryDir, tag, tagObject string) error {
-	if err := checkTagRef(ctx, repositoryDir, tag); err != nil {
+	if err := CheckTagRef(ctx, repositoryDir, tag); err != nil {
 		return err
 	}
 	if !validObjectID(tagObject) {

publish_test.go

@@ -18,6 +18,40 @@ import (
 
 const releaseNote = "# Sample App v1.2.3\n\nA source release.\n\nUpgrade notes stay intact.\n"
 
+func TestCheckRejectsInvalidDerivedTagBeforeValidation(t *testing.T) {
+	for _, module := range []string{"module space", "module.lock"} {
+		t.Run(module, func(t *testing.T) {
+			repo := newPublishFixture(t)
+			writeFile(t, repo.work, module+"/go.mod", "module example.com/nested\n\ngo 1.25.0\n")
+			writeFile(t, repo.work, module+"/docs/releases/v1.2.3.md", releaseNote)
+			gitRun(t, repo.work, "add", module)
+			gitRun(t, repo.work, "commit", "-m", "add module")
+			bin := t.TempDir()
+			marker := filepath.Join(t.TempDir(), "go-ran")
+			if err := os.WriteFile(filepath.Join(bin, "go"), []byte("#!/bin/sh\nprintf ran > \"$CANDIDATE_GO_MARKER\"\nexit 1\n"), 0o755); err != nil {
+				t.Fatal(err)
+			}
+			t.Setenv("PATH", bin+string(os.PathListSeparator)+os.Getenv("PATH"))
+			t.Setenv("CANDIDATE_GO_MARKER", marker)
+			called := false
+			got, err := releasekit.Check(context.Background(), releasekit.ReleaseRequest{
+				RepositoryDir: repo.work, ModuleDir: module, Product: "Sample App", Version: "v1.2.3",
+				AdditionalChecks: func(context.Context, releasekit.Candidate) error { called = true; return nil },
+				Build:            &releasekit.BuildSpec{MainPackage: ".", BinaryName: "fixture", Targets: []releasekit.Target{{OS: "linux", Arch: "amd64"}}},
+			})
+			if err == nil || errors.Is(err, releasekit.ErrInvalidVersion) || !strings.Contains(err.Error(), "invalid Git tag name") || got.Tag != module+"/v1.2.3" || got.ModulePath != "example.com/nested" {
+				t.Fatalf("candidate = %#v, error = %v", got, err)
+			}
+			if called {
+				t.Fatal("additional checks ran")
+			}
+			if _, err := os.Stat(marker); !os.IsNotExist(err) {
+				t.Fatalf("Go validation or build ran: %v", err)
+			}
+		})
+	}
+}
+
 func TestCandidateOperationsDiscoverGoOnlyWhenLaterWorkNeedsIt(t *testing.T) {
 	gitPath := mustLookPath(t, "git")
 	gitOnly := t.TempDir()