[AI Datamapper] Fix crash when LLM returns no mappings

[VellummyilumVinoth]

Description

It resolves: wso2/product-ballerina-integrator#2031

Goals

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• Added reusable UI components to the ui-toolkit. Follow the intructions when adding the componenent.
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• Matches with the native VSCode look and feel.

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• Added Icons to the font-wso2-vscode. Follow the instructions.

User stories

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Documentation

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Summary by CodeRabbit

• Bug Fixes
  • Gracefully stop AI-driven mapping flows and show a clear user warning when no mappings are produced, preventing subsequent code generation or repair steps and avoiding downstream errors.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

The PR adds three defensive guards in the AI datamapper to detect empty LLM-generated mappings, emit a user-facing warning, stop DataMap processing, and return early to prevent further repair or generation steps.

Changes

Cohort / File(s)	Summary
AI Datamapper Empty Mapping Guards workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts	Added a NO_MAPPINGS_GENERATED_WARNING constant and three early-return guards in generateMappingCodeCore and generateInlineMappingCodeCore to emit the warning, stop DataMap, and return when the LLM returns no mappings.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

• Areas to check:
  • Correct placement of early returns so necessary cleanup/state transitions still occur.
  • Consistency and clarity of the warning content string.
  • No missing telemetry/logging for the new stop events.

Possibly related PRs

• [AI Datamapper] Fix mapping compilation error fields #904 — Modifies the same datamapper functions and handles empty or error-prone mapping flows; closely related to this early-stop approach.

Suggested reviewers

• hevayo
• gigara

Poem

🐇 I hopped to map, but found no thread,
So I whispered a warning and rested my head.
No timeout tumble, no frantic race—
A gentle stop, with a rabbit's grace. 🥕

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The PR description is largely incomplete. While it references the linked issue, critical sections like Goals, Approach, Release note, and test coverage contain only template placeholders without substantive content.	Complete the Goals, Approach, Release note, automation tests, and test environment sections with specific implementation details and testing information.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main change: fixing a crash when the LLM returns no mappings in AI Datamapper.
Linked Issues check	✅ Passed	The code changes directly address the linked issue by adding null/empty-mapping checks with user-facing warnings, preventing crashes and timeouts as required.
Out of Scope Changes check	✅ Passed	All changes are scoped to handling empty mappings in the datamapper service, which is directly aligned with the linked issue requirements.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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📜 Recent review details

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Review profile: CHILL

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📥 Commits

Reviewing files that changed from the base of the PR and between 3dfd8e1 and 2172e21.

📒 Files selected for processing (1)

• workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts (3 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts

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Actionable comments posted: 0

🧹 Nitpick comments (1)

workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts (1)

710-721: LGTM! Inline mapping path is now protected from the crash.

The guard correctly handles the empty mappings scenario for inline code generation, matching the pattern used in generateMappingCodeCore.

Consider extracting the warning message into a shared constant to eliminate duplication:

const NO_MAPPINGS_WARNING = `**No Relevant Mappings Generated**\n\n` +
    `The AI was unable to identify compatible field mappings between the input and output structures.\n\n` +
    `**Suggestions:**\n` +
    `- Check if input and output record structures are correct\n` +
    `- Try providing mapping hints or examples\n`;

Then use it at both lines 351 and 718:

-    const warningMessage = `**No Relevant Mappings Generated**\n\n` +
-        `The AI was unable to identify compatible field mappings between the input and output structures.\n\n` +
-        `**Suggestions:**\n` +
-        `- Check if input and output record structures are correct\n` +
-        `- Try providing mapping hints or examples\n`;
-
-    eventHandler({ type: "content_block", content: warningMessage });
+    eventHandler({ type: "content_block", content: NO_MAPPINGS_WARNING });

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between ba5b5a7 and 3dfd8e1.

📒 Files selected for processing (1)

• workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts (2 hunks)

🧰 Additional context used

🧠 Learnings (5)

📚 Learning: 2025-11-26T06:37:07.886Z

Learnt from: KCSAbeywickrama
Repo: wso2/vscode-extensions PR: 653
File: workspaces/bi/bi-extension/src/test/e2e-playwright-tests/data-mapper/dm-data/array-inner/inline/map3.bal.txt:6-8
Timestamp: 2025-11-26T06:37:07.886Z
Learning: In workspaces/bi/bi-extension/src/test/e2e-playwright-tests/data-mapper/dm-data/ directories, BAL test data files (such as those in array-inner/inline/, array-root/inline/, basic/inline/, and their reusable counterparts) may intentionally contain type errors and other violations. These are comparison files used to test data mapper functionality and error handling, so such errors should not be flagged as issues.

Applied to files:

• workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts

📚 Learning: 2025-11-26T06:35:19.217Z

Learnt from: KCSAbeywickrama
Repo: wso2/vscode-extensions PR: 653
File: workspaces/bi/bi-extension/src/test/e2e-playwright-tests/data-mapper/DataMapperUtils.ts:173-178
Timestamp: 2025-11-26T06:35:19.217Z
Learning: In workspaces/bi/bi-extension/src/test/e2e-playwright-tests/data-mapper/DataMapperUtils.ts, the commented-out debugging block in the verifyFileContent function (lines 172-177 containing console.log, page.pause, and updateDataFileSync) is intentionally kept as a developer utility for updating test data files when needed. It should not be removed.

Applied to files:

• workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts

📚 Learning: 2025-11-26T06:34:09.752Z

Learnt from: KCSAbeywickrama
Repo: wso2/vscode-extensions PR: 653
File: workspaces/bi/bi-extension/src/test/e2e-playwright-tests/data-mapper/DataMapperUtils.ts:128-134
Timestamp: 2025-11-26T06:34:09.752Z
Learning: In workspaces/bi/bi-extension/src/test/e2e-playwright-tests/data-mapper/DataMapperUtils.ts, the goPrevViewBreadcrumb() method is only called when in a focused view, ensuring breadcrumbs are always present. No guard for empty breadcrumbs is needed.

Applied to files:

• workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts

📚 Learning: 2025-11-26T07:49:56.428Z

Learnt from: KCSAbeywickrama
Repo: wso2/vscode-extensions PR: 653
File: workspaces/bi/bi-extension/src/test/e2e-playwright-tests/data-mapper/DataMapperUtils.ts:136-141
Timestamp: 2025-11-26T07:49:56.428Z
Learning: In workspaces/bi/bi-extension/src/test/e2e-playwright-tests/data-mapper/DataMapperUtils.ts, the goPrevViewBackButton() method is only called when in a focused view, ensuring breadcrumbs are always present. No guard for empty breadcrumbs is needed.

Applied to files:

• workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts

📚 Learning: 2025-11-26T06:33:22.950Z

Learnt from: KCSAbeywickrama
Repo: wso2/vscode-extensions PR: 653
File: workspaces/bi/bi-extension/src/test/e2e-playwright-tests/data-mapper/DataMapperUtils.ts:86-112
Timestamp: 2025-11-26T06:33:22.950Z
Learning: In workspaces/bi/bi-extension/src/test/e2e-playwright-tests/data-mapper/DataMapperUtils.ts, empty catch blocks around progress ring waitForSelector calls (state: 'attached' and 'detached') are intentional. The progress ring duration depends on machine performance and may appear very briefly, causing the wait to miss the event. The try-catch allows the test to proceed gracefully regardless of timing.

Applied to files:

• workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts

🔇 Additional comments (1)

workspaces/ballerina/ballerina-extension/src/features/ai/service/datamapper/datamapper.ts (1)

343-354: LGTM! Crash prevention guard is correctly implemented.

The early-return guard successfully prevents the operation timeout crash by handling empty mapping results gracefully before attempting to update source code. The warning message is user-friendly and provides actionable suggestions.

One minor note: verify that the temporary directory created at line 323 is cleaned up appropriately when this early return path is taken. Confirm this is handled by a cleanup mechanism elsewhere (such as a try/finally block or resource cleanup handler) to avoid potential resource leaks.