fix: improve install and add error messages for pre-release drivers

cmd/dbc/add.go

@@ -149,7 +149,14 @@ func (m addModel) Init() tea.Cmd {
 				}
 			} else {
 				if !m.Pre && !drv.HasNonPrerelease() {
-					err := fmt.Errorf("driver `%s` not found in driver registry index", spec.Name)
+					var err error
+					if len(drv.PkgInfo) > 0 {
+						// Has packages, but they're all prereleases
+						err = fmt.Errorf("driver `%s` not found in driver registry index (but prerelease versions filtered out); try: dbc add --pre %s", spec.Name, spec.Name)
+					} else {
+						// No packages. Very unlikely edge case.
+						err = fmt.Errorf("driver `%s` not found in driver registry index", spec.Name)
+					}
 					// If we have registry errors, enhance the error message
 					if registryErrors != nil {
 						return fmt.Errorf("%w\n\nNote: Some driver registries were unavailable:\n%s", err, registryErrors.Error())

cmd/dbc/add_test.go

@@ -274,7 +274,7 @@ func (suite *SubcommandTestSuite) TestAddWithoutPreOnlyPrereleaseDriver() {
 		baseModel{getDriverRegistry: getTestDriverRegistry, downloadPkg: downloadTestPkg})
 
 	out := suite.runCmdErr(m)
-	suite.Contains(out, "driver `test-driver-only-pre` not found in driver registry index")
+	suite.Contains(out, "driver `test-driver-only-pre` not found in driver registry index (but prerelease versions filtered out); try: dbc add --pre test-driver-only-pre")
 }
 
 func (suite *SubcommandTestSuite) TestAddWithPreAndConstraint() {

cmd/dbc/install_test.go

@@ -346,6 +346,8 @@ func (suite *SubcommandTestSuite) TestInstallWithoutPreOnlyPrereleaseDriver() {
 	out := suite.runCmdErr(m)
 
 	suite.Contains(out, "driver `test-driver-only-pre` not found")
+	suite.Contains(out, "but prerelease versions filtered out")
+	suite.Contains(out, "try: dbc install --pre test-driver-only-pre")
 	suite.driverIsNotInstalled("test-driver-only-pre")
 }
 

drivers.go

@@ -461,12 +461,19 @@ func (d Driver) Versions(platformTuple string) semver.Collection {
 
 func (d Driver) GetPackage(version *semver.Version, platformTuple string, allowPrerelease bool) (PkgInfo, error) {
 	pkglist := d.PkgInfo
+
+	// Filter out pre-releases and record whether any pre-releases were filtered
+	// out so we can produce a more helpful error message
 	if !allowPrerelease && (version == nil || version.Prerelease() != "") {
+		hadPackages := len(d.PkgInfo) > 0
 		pkglist = slices.Collect(filter(slices.Values(d.PkgInfo), func(p pkginfo) bool {
 			return p.Version.Prerelease() == ""
 		}))
 		if len(pkglist) == 0 {
-			return PkgInfo{}, fmt.Errorf("driver `%s` not found (but prerelease versions filtered out)", d.Path)
+			if hadPackages {
+				return PkgInfo{}, fmt.Errorf("driver `%s` not found (but prerelease versions filtered out); try: dbc install --pre %s", d.Path, d.Path)
+			}
+			return PkgInfo{}, fmt.Errorf("driver `%s` not found", d.Path)
 		}
 	}