fix: improve Code Index error messages with detailed diagnostics

- Enhanced validation-helpers.ts to preserve original error details
- Added specific error messages for common configuration issues
- Improved Gemini embedder error handling with provider-specific guidance
- Added new i18n translations for detailed error messages
- Updated tests to cover new error handling scenarios

Fixes #7743

src/i18n/locales/en/embeddings.json

@@ -39,7 +39,11 @@
 		"invalidModel": "Invalid model. Please check your model configuration.",
 		"invalidResponse": "Invalid response from embedder service. Please check your configuration.",
 		"apiKeyRequired": "API key is required for this embedder",
-		"baseUrlRequired": "Base URL is required for this embedder"
+		"baseUrlRequired": "Base URL is required for this embedder",
+		"hostNotFound": "Cannot resolve host: {{url}}. Please verify the URL is correct and accessible.",
+		"connectionRefused": "Connection refused to {{url}}. Please ensure the service is running and accessible.",
+		"connectionTimeout": "Connection timed out. Please check your network connection and try again.",
+		"geminiAuthDetails": "For Gemini, ensure you have a valid API key from Google AI Studio (makersuite.google.com/app/apikey)."
 	},
 	"serviceFactory": {
 		"openAiConfigMissing": "OpenAI configuration missing for embedder creation",

src/services/code-index/embedders/__tests__/gemini.spec.ts

@@ -162,12 +162,68 @@ describe("GeminiEmbedder", () => {
 			expect(result).toEqual({ valid: true })
 		})
 
-		it("should pass through validation errors from OpenAICompatibleEmbedder", async () => {
+		it("should enhance authentication error messages with Gemini-specific guidance", async () => {
 			// Arrange
 			embedder = new GeminiEmbedder("test-api-key")
 			mockValidateConfiguration.mockResolvedValue({
 				valid: false,
-				error: "embeddings:validation.authenticationFailed",
+				error: "Authentication failed (HTTP 401)",
+			})
+
+			// Act
+			const result = await embedder.validateConfiguration()
+
+			// Assert
+			expect(mockValidateConfiguration).toHaveBeenCalled()
+			expect(result.valid).toBe(false)
+			expect(result.error).toContain("Authentication failed (HTTP 401)")
+			expect(result.error).toContain("Google AI Studio")
+			expect(result.error).toContain("makersuite.google.com/app/apikey")
+		})
+
+		it("should enhance model error messages with supported models list", async () => {
+			// Arrange
+			embedder = new GeminiEmbedder("test-api-key", "invalid-model")
+			mockValidateConfiguration.mockResolvedValue({
+				valid: false,
+				error: "Model not found (HTTP 404)",
+			})
+
+			// Act
+			const result = await embedder.validateConfiguration()
+
+			// Assert
+			expect(result.valid).toBe(false)
+			expect(result.error).toContain("Model not found")
+			expect(result.error).toContain("text-embedding-004")
+			expect(result.error).toContain("gemini-embedding-001")
+			expect(result.error).toContain("dimension: 768")
+			expect(result.error).toContain("dimension: 2048")
+		})
+
+		it("should enhance connection error messages with API endpoint info", async () => {
+			// Arrange
+			embedder = new GeminiEmbedder("test-api-key")
+			mockValidateConfiguration.mockResolvedValue({
+				valid: false,
+				error: "connection refused",
+			})
+
+			// Act
+			const result = await embedder.validateConfiguration()
+
+			// Assert
+			expect(result.valid).toBe(false)
+			expect(result.error).toContain("connection refused")
+			expect(result.error).toContain("https://generativelanguage.googleapis.com/v1beta/openai/")
+		})
+
+		it("should pass through validation errors without enhancement for non-specific errors", async () => {
+			// Arrange
+			embedder = new GeminiEmbedder("test-api-key")
+			mockValidateConfiguration.mockResolvedValue({
+				valid: false,
+				error: "Some other error",
 			})
 
 			// Act
@@ -177,17 +233,38 @@ describe("GeminiEmbedder", () => {
 			expect(mockValidateConfiguration).toHaveBeenCalled()
 			expect(result).toEqual({
 				valid: false,
-				error: "embeddings:validation.authenticationFailed",
+				error: "Some other error",
 			})
 		})
 
-		it("should handle validation exceptions", async () => {
+		it("should handle validation exceptions with detailed error message", async () => {
 			// Arrange
-			embedder = new GeminiEmbedder("test-api-key")
-			mockValidateConfiguration.mockRejectedValue(new Error("Validation failed"))
+			embedder = new GeminiEmbedder("test-api-key", "test-model")
+			mockValidateConfiguration.mockRejectedValue(new Error("Network error"))
 
-			// Act & Assert
-			await expect(embedder.validateConfiguration()).rejects.toThrow("Validation failed")
+			// Act
+			const result = await embedder.validateConfiguration()
+
+			// Assert
+			expect(result.valid).toBe(false)
+			expect(result.error).toContain("Gemini embedder validation failed")
+			expect(result.error).toContain("Network error")
+			expect(result.error).toContain("test-model")
+		})
+
+		it("should handle non-Error exceptions gracefully", async () => {
+			// Arrange
+			embedder = new GeminiEmbedder("test-api-key", "test-model")
+			mockValidateConfiguration.mockRejectedValue("String error")
+
+			// Act
+			const result = await embedder.validateConfiguration()
+
+			// Assert
+			expect(result.valid).toBe(false)
+			expect(result.error).toContain("Gemini embedder validation failed")
+			expect(result.error).toContain("String error")
+			expect(result.error).toContain("test-model")
 		})
 	})
 })

src/services/code-index/embedders/gemini.ts

@@ -69,15 +69,39 @@ export class GeminiEmbedder implements IEmbedder {
 	async validateConfiguration(): Promise<{ valid: boolean; error?: string }> {
 		try {
 			// Delegate validation to the OpenAI-compatible embedder
-			// The error messages will be specific to Gemini since we're using Gemini's base URL
-			return await this.openAICompatibleEmbedder.validateConfiguration()
+			const result = await this.openAICompatibleEmbedder.validateConfiguration()
+
+			// If validation failed, enhance the error message with Gemini-specific guidance
+			if (!result.valid && result.error) {
+				// Check for common Gemini-specific issues
+				if (
+					result.error.includes("401") ||
+					result.error.includes("403") ||
+					result.error.includes("Authentication")
+				) {
+					result.error = `${result.error}. For Gemini, ensure you have a valid API key from Google AI Studio (makersuite.google.com/app/apikey) and that it's correctly configured.`
+				} else if (result.error.includes("404") || result.error.includes("model")) {
+					result.error = `${result.error}. Supported Gemini models: text-embedding-004 (dimension: 768), gemini-embedding-001 (dimension: 2048).`
+				} else if (result.error.includes("connection") || result.error.includes("host")) {
+					result.error = `${result.error}. Gemini API endpoint: ${GeminiEmbedder.GEMINI_BASE_URL}`
+				}
+			}
+
+			return result
 		} catch (error) {
 			TelemetryService.instance.captureEvent(TelemetryEventName.CODE_INDEX_ERROR, {
 				error: error instanceof Error ? error.message : String(error),
 				stack: error instanceof Error ? error.stack : undefined,
 				location: "GeminiEmbedder:validateConfiguration",
+				modelId: this.modelId,
 			})
-			throw error
+
+			// Provide a more informative error message
+			const errorMessage = error instanceof Error ? error.message : String(error)
+			return {
+				valid: false,
+				error: `Gemini embedder validation failed: ${errorMessage}. Please check your API key and model configuration (current model: ${this.modelId}).`,
+			}
 		}
 	}
 

src/services/code-index/service-factory.ts

@@ -93,19 +93,50 @@ export class CodeIndexServiceFactory {
 	 */
 	public async validateEmbedder(embedder: IEmbedder): Promise<{ valid: boolean; error?: string }> {
 		try {
-			return await embedder.validateConfiguration()
+			const result = await embedder.validateConfiguration()
+
+			// If validation failed but no specific error was provided, add context
+			if (!result.valid && !result.error) {
+				const config = this.configManager.getConfig()
+				result.error =
+					t("embeddings:validation.configurationError") +
+					` (Provider: ${config.embedderProvider}, Model: ${config.modelId || "default"})`
+			}
+
+			return result
 		} catch (error) {
-			// Capture telemetry for the error
+			// Capture telemetry for the error with additional context
+			const config = this.configManager.getConfig()
 			TelemetryService.instance.captureEvent(TelemetryEventName.CODE_INDEX_ERROR, {
 				error: error instanceof Error ? error.message : String(error),
 				stack: error instanceof Error ? error.stack : undefined,
 				location: "validateEmbedder",
+				provider: config.embedderProvider,
+				model: config.modelId,
 			})
 
-			// If validation throws an exception, preserve the original error message
+			// Provide detailed error message with context
+			let errorMessage = error instanceof Error ? error.message : String(error)
+
+			// Add provider-specific guidance
+			if (config.embedderProvider === "gemini") {
+				if (errorMessage.includes("401") || errorMessage.includes("403") || errorMessage.includes("API key")) {
+					errorMessage +=
+						". Please ensure your Gemini API key is valid and correctly configured in the settings."
+				}
+			} else if (config.embedderProvider === "openai") {
+				if (errorMessage.includes("401") || errorMessage.includes("403")) {
+					errorMessage += ". Please check your OpenAI API key in the settings."
+				}
+			} else if (config.embedderProvider === "ollama") {
+				if (errorMessage.includes("connection") || errorMessage.includes("ECONNREFUSED")) {
+					errorMessage += ". Please ensure Ollama is running locally and accessible."
+				}
+			}
+
 			return {
 				valid: false,
-				error: error instanceof Error ? error.message : "embeddings:validation.configurationError",
+				error: errorMessage,
 			}
 		}
 	}

src/services/code-index/shared/validation-helpers.ts

@@ -167,34 +167,88 @@ export function handleValidationError(
 	// Check for status-based errors first
 	const statusError = getErrorMessageForStatus(statusCode, embedderType)
 	if (statusError) {
-		return { valid: false, error: statusError }
+		// Include additional context for authentication errors
+		if (statusCode === 401 || statusCode === 403) {
+			const details = embedderType === "gemini" ? t("embeddings:validation.geminiAuthDetails") : ""
+			return { valid: false, error: details ? `${statusError} ${details}` : statusError }
+		}
+		// Include status code in error for better debugging
+		return { valid: false, error: `${statusError} (HTTP ${statusCode})` }
 	}
 
-	// Check for connection errors
+	// Check for connection errors with more specific messages
 	if (errorMessage) {
-		if (
-			errorMessage.includes("ENOTFOUND") ||
-			errorMessage.includes("ECONNREFUSED") ||
-			errorMessage.includes("ETIMEDOUT") ||
-			errorMessage === "AbortError" ||
-			errorMessage.includes("HTTP 0:") ||
-			errorMessage === "No response"
-		) {
+		if (errorMessage.includes("ENOTFOUND")) {
+			const url = extractUrlFromError(errorMessage)
+			return {
+				valid: false,
+				error: t("embeddings:validation.hostNotFound", { url: url || "configured endpoint" }),
+			}
+		}
+
+		if (errorMessage.includes("ECONNREFUSED")) {
+			const url = extractUrlFromError(errorMessage)
+			return {
+				valid: false,
+				error: t("embeddings:validation.connectionRefused", { url: url || "configured endpoint" }),
+			}
+		}
+
+		if (errorMessage.includes("ETIMEDOUT")) {
+			return {
+				valid: false,
+				error: t("embeddings:validation.connectionTimeout"),
+			}
+		}
+
+		if (errorMessage === "AbortError" || errorMessage.includes("HTTP 0:") || errorMessage === "No response") {
 			return { valid: false, error: t("embeddings:validation.connectionFailed") }
 		}
 
 		if (errorMessage.includes("Failed to parse response JSON")) {
 			return { valid: false, error: t("embeddings:validation.invalidResponse") }
 		}
+
+		// Check for API key related errors
+		if (errorMessage.includes("API key") || errorMessage.includes("api key") || errorMessage.includes("api-key")) {
+			return { valid: false, error: t("embeddings:validation.invalidApiKey") }
+		}
+
+		// Check for model-related errors
+		if (
+			errorMessage.includes("model") &&
+			(errorMessage.includes("not found") || errorMessage.includes("does not exist"))
+		) {
+			return { valid: false, error: t("embeddings:validation.modelNotAvailable") }
+		}
 	}
 
 	// For generic errors, preserve the original error message if it's not a standard one
 	if (errorMessage && errorMessage !== "Unknown error") {
-		return { valid: false, error: errorMessage }
+		// Provide more context with the error
+		return {
+			valid: false,
+			error: `${t("embeddings:validation.configurationError")}: ${errorMessage}`,
+		}
 	}
 
-	// Fallback to generic error
-	return { valid: false, error: t("embeddings:validation.configurationError") }
+	// Fallback to generic error with embedder type for context
+	return {
+		valid: false,
+		error: `${t("embeddings:validation.configurationError")} (${embedderType})`,
+	}
+}
+
+/**
+ * Extracts URL from error message if present
+ */
+function extractUrlFromError(errorMessage: string): string | undefined {
+	// Try to extract URL from common error patterns
+	const urlMatch = errorMessage.match(/(?:https?:\/\/[^\s]+)|(?:getaddrinfo\s+\w+\s+([^\s]+))/i)
+	if (urlMatch) {
+		return urlMatch[1] || urlMatch[0]
+	}
+	return undefined
 }
 
 /**