Backend langchain #1526

Artuomka · 2026-01-22T16:23:07Z

No description provided.

…method

Copilot

Pull request overview

This pull request introduces a new AI core abstraction layer using LangChain for backend AI functionality. The changes refactor the existing AI implementation to support multiple AI providers (OpenAI and AWS Bedrock) through a unified interface.

Changes:

Adds LangChain integration with @langchain/core, @langchain/openai, and @langchain/aws packages
Introduces a new ai-core module with provider abstraction and service layer
Implements tool-based AI interactions with streaming support for database queries
Refactors existing AI functionality to use the new abstraction layer

Reviewed changes

Copilot reviewed 23 out of 25 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
backend/package.json	Adds langchain dependencies (@langchain/core, @langchain/openai, @langchain/aws, langchain)
backend/yarn.lock	Lock file updates for new dependencies including langchain ecosystem packages
backend/src/ai-core/ai-core.module.ts	New global module providing AI core services and providers
backend/src/ai-core/services/ai-core.service.ts	Unified service layer for AI operations supporting multiple providers
backend/src/ai-core/providers/langchain-openai.provider.ts	OpenAI provider implementation using LangChain
backend/src/ai-core/providers/langchain-bedrock.provider.ts	AWS Bedrock provider implementation using LangChain
backend/src/ai-core/interfaces/	TypeScript interfaces defining AI provider contracts
backend/src/ai-core/tools/	Database query tools, validators, and prompt builders
backend/src/ai-core/utils/message-builder.ts	Builder pattern for constructing AI message chains
backend/src/entities/ai/use-cases/request-info-from-table-with-ai-v5.use.case.ts	New use case implementing streaming AI responses with tool execution loop
backend/src/entities/ai/ai.service.ts	Updated to use new AICoreService instead of direct Bedrock provider
backend/src/entities/ai/ai.module.ts	Updated module configuration to use new V5 use case
backend/src/app.module.ts	Imports new AICoreModule
backend/src/helpers/app/get-requeired-env-variable.ts	Adds getOptionalEnvVariable helper function
backend/src/entities/table-settings/common-table-settings/use-cases/update-table-settings.use.case.ts	Formatting changes (spaces to tabs)
backend/src/entities/ai/user-ai-requests-v2.controller.ts	Formatting changes (quote style normalization)

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Copilot · 2026-01-22T16:27:59Z

backend/src/ai-core/providers/langchain-openai.provider.ts

+	private openaiClient: OpenAI;
+
+	constructor() {
+		const apiKey = getOptionalEnvVariable('OPENAI_API_KEY');


The OpenAI client is initialized with an optional API key that may be undefined. If the environment variable is not set, this could lead to runtime errors when the client is used. Consider validating that the API key exists when the provider is actually used, or document that OPENAI_API_KEY is optional if it's intended to support scenarios where OpenAI is not configured.

Suggested change

const apiKey = getOptionalEnvVariable('OPENAI_API_KEY');

const apiKey = getRequiredEnvVariable('OPENAI_API_KEY');

Copilot · 2026-01-22T16:27:59Z

backend/src/ai-core/providers/langchain-bedrock.provider.ts

+							} catch {
+								// Accumulate partial JSON - will be parsed when complete


Empty catch block silently ignores JSON parsing errors. While the error is handled by accumulating partial JSON, consider logging this for debugging purposes or adding a comment explaining why the error is intentionally ignored.

Suggested change

} catch {

// Accumulate partial JSON - will be parsed when complete

} catch (error) {

// Accumulate partial JSON - will be parsed when complete; log for debugging purposes

console.debug('Failed to parse toolCallChunk.args as JSON; continuing to accumulate partial data.', {

args: toolCallChunk.args,

error,

});

Copilot · 2026-01-22T16:28:00Z

backend/src/ai-core/providers/langchain-openai.provider.ts

+						} catch {
+							// Failed to parse args


Empty catch blocks at lines 227-229 and 351-353 silently ignore JSON parsing errors. Consider adding comments to explain why these errors are intentionally ignored or add debug logging.

Suggested change

} catch {

// Failed to parse args

} catch (error) {

// Intentionally ignore JSON parse errors for tool arguments:

// we fall back to an empty argument object to avoid failing the entire stream.

// Log at debug/warn level to aid troubleshooting without impacting runtime behavior.

// eslint-disable-next-line no-console

console.warn('Failed to parse tool call args; using empty arguments instead.', {

error,

toolName: toolCallData.name,

rawArgs: toolCallData.argsString,

});

Copilot · 2026-01-22T16:28:00Z

backend/src/ai-core/tools/query-validators.ts

+			JSON.parse(possibleJson);
+			return possibleJson;
+		} catch (_parseErr) {
+			console.error('Could not sanitize JSON, returning empty object');


The console.error call is using console directly instead of a proper logging framework. Consider using the NestJS Logger or the application's logging infrastructure for consistency.

Copilot · 2026-01-22T16:28:00Z

backend/src/entities/ai/use-cases/request-info-from-table-with-ai-v5.use.case.ts

+						result = JSON.stringify({ error: `Unknown tool: ${toolCall.name}` });
+				}
+			} catch (error) {
+				result = JSON.stringify({ error: error.message });


The error handler at line 256 is accessing error.message without checking if error is actually an Error object. This could cause a runtime error if a non-Error object is thrown. Consider using a type guard or optional chaining: error?.message || 'Unknown error'.

Suggested change

result = JSON.stringify({ error: error.message });

const errorMessage =

error instanceof Error

? error.message

: typeof error === 'string'

? error

: 'Unknown error';

result = JSON.stringify({ error: errorMessage });

Copilot · 2026-01-22T16:28:01Z

backend/src/entities/ai/use-cases/request-info-from-table-with-ai-v5.use.case.ts

+			}
+			response.end();
+		} catch (error) {
+			await slackPostMessage(error?.message);


The error handler at line 112 is accessing error?.message which is good, but if error is null/undefined, it will pass undefined to slackPostMessage, potentially causing issues. Consider providing a fallback: error?.message || 'Unknown error occurred'.

Suggested change

await slackPostMessage(error?.message);

await slackPostMessage(error?.message || 'Unknown error occurred');

Copilot · 2026-01-22T16:28:01Z

backend/src/entities/ai/use-cases/request-info-from-table-with-ai-v5.use.case.ts

+				currentMessages = toolMessageBuilder.build();
+
+				depth++;
+			} catch (loopError) {


The catch block at line 181-183 simply rethrows the error without adding any context or cleanup. Consider adding logging or additional context about where the error occurred in the tool loop, or removing the try-catch if no specific handling is needed.

Suggested change

} catch (loopError) {

} catch (loopError) {

Sentry.captureException(loopError);

Copilot · 2026-01-22T16:28:01Z

backend/src/ai-core/providers/langchain-openai.provider.ts

+	AIToolResult,
+	AIToolCall,
+} from '../interfaces/ai-provider.interface.js';
+import { getOptionalEnvVariable, getRequiredEnvVariable } from '../../helpers/app/get-requeired-env-variable.js';


Typo in filename: "get-requeired-env-variable.ts" should be "get-required-env-variable.ts". The word "required" is misspelled.

Suggested change

import { getOptionalEnvVariable, getRequiredEnvVariable } from '../../helpers/app/get-requeired-env-variable.js';

import { getOptionalEnvVariable, getRequiredEnvVariable } from '../../helpers/app/get-required-env-variable.js';

Copilot · 2026-01-22T16:28:02Z

backend/src/ai-core/providers/langchain-openai.provider.ts

+				throw streamError;
+			}
+
+			for (const [index, toolCallData] of currentToolCalls.entries()) {


Unused variable index.

Suggested change

for (const [index, toolCallData] of currentToolCalls.entries()) {

for (const toolCallData of currentToolCalls.values()) {

Artuomka added 8 commits January 19, 2026 15:01

added langchain

655f6e4

Refactor environment variable handling to include optional retrieval …

9807b6c

…method

Update default model ID in LangchainBedrockProvider

ac3b142

Merge branch 'main' into backend_langchain

6d67632

Merge branch 'main' into backend_langchain

1131cf7

Add new parameters to table settings update and controller methods

af71412

Merge branch 'main' into backend_langchain

7985662

Merge branch 'main' into backend_langchain

f95bcfe

Copilot AI review requested due to automatic review settings January 22, 2026 16:23

Copilot started reviewing on behalf of Artuomka January 22, 2026 16:23 View session

Copilot AI reviewed Jan 22, 2026

View reviewed changes

Artuomka enabled auto-merge January 23, 2026 06:19

Merge branch 'main' into backend_langchain

3cb2753

Artuomka merged commit a14f1b6 into main Jan 23, 2026
19 checks passed

Artuomka deleted the backend_langchain branch January 23, 2026 06:41

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	const apiKey = getOptionalEnvVariable('OPENAI_API_KEY');
	const apiKey = getRequiredEnvVariable('OPENAI_API_KEY');

		} catch {
		// Accumulate partial JSON - will be parsed when complete

-						} catch {
-							// Failed to parse args
+						} catch (error) {
+							// Intentionally ignore JSON parse errors for tool arguments:
+							// we fall back to an empty argument object to avoid failing the entire stream.
+							// Log at debug/warn level to aid troubleshooting without impacting runtime behavior.
+							// eslint-disable-next-line no-console
+							console.warn('Failed to parse tool call args; using empty arguments instead.', {
+								error,
+								toolName: toolCallData.name,
+								rawArgs: toolCallData.argsString,
+							});

-				result = JSON.stringify({ error: error.message });
+				const errorMessage =
+					error instanceof Error
+						? error.message
+						: typeof error === 'string'
+						? error
+						: 'Unknown error';
+				result = JSON.stringify({ error: errorMessage });

	await slackPostMessage(error?.message);
	await slackPostMessage(error?.message \|\| 'Unknown error occurred');

	} catch (loopError) {
	} catch (loopError) {
	Sentry.captureException(loopError);

	import { getOptionalEnvVariable, getRequiredEnvVariable } from '../../helpers/app/get-requeired-env-variable.js';
	import { getOptionalEnvVariable, getRequiredEnvVariable } from '../../helpers/app/get-required-env-variable.js';

	for (const [index, toolCallData] of currentToolCalls.entries()) {
	for (const toolCallData of currentToolCalls.values()) {

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