refactor(backend): extract Gemini model fallback into reusable utility (DRY)#439
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Introduce utils/geminiHelper.js with two exported functions:
- generateWithFallback(apiKey, parts, options, retries, initialDelay)
Tries candidate models in order (env GEMINI_MODEL first, then the
hardcoded fallback list) and supports exponential-backoff retries for
transient errors (429 / 503 / timeout / network).
- generateChatWithFallback(apiKey, prompt, history, options)
Same model-fallback strategy but initialises a Gemini chat session
(startChat + sendMessage) for the conversational AI endpoint.
The duplicated ~15-line fallback loops that appeared in 6 locations
across 5 files are removed and replaced with single calls to the helper:
controllers/aiController.js — 3 loops → 3 helper calls
controllers/resumeController.js — 1 loop → 1 helper call
routes/aiRoutes.js — 1 loop → 1 helper call (chat)
routes/AptitudeQuestions.js — 1 loop + local isRetryableError
+ generateWithRetry → 1 helper call
Benefits:
* Single source of truth for model list and fallback order
* Retry logic (previously only in AptitudeQuestions) is now available
to all callers via the retries parameter
* ~90 lines of boilerplate removed
* Fallback helper is independently unit-testable
Closes #<issue-number>
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Hello @KaranUnique, I have completed my assigned work so please review the changes and merge the PR under ECSoC. |
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Summary
The Gemini model fallback loop was duplicated across 6 locations in 5 files.
This PR extracts it into a single reusable utility at
utils/geminiHelper.js.Changes
New:
utils/geminiHelper.jsgenerateWithFallback(apiKey, parts, options?, retries?, initialDelay?)— triescandidate models in order (env var first), with optional exponential-backoff
retries for transient errors (429, 503, timeout, network)
generateChatWithFallback(apiKey, prompt, history?, options?)— same fallbackstrategy for chat-session endpoints using
startChat+sendMessageUpdated files
controllers/aiController.jscontrollers/resumeController.jsroutes/aiRoutes.jsroutes/AptitudeQuestions.jsBenefits
Testing
All existing behaviour is preserved. No API surface changed.
Closes #435