LangSmith blueprint · Banking
Customer feedback to regression tests
Thumbs-down answers are routed to reviewers, corrected, and kept as tests for every later release.
- Steps
- 7
- Subjective questions
- 32
- Objective questions
- 32
The problem and the outcome
Problem: Bad bot answers are found only when customers complain at a branch.
Outcome: Every bad answer becomes a test case, so the same mistake does not come back.
Architecture
How it works, step by step
- A customer asks the bank's assistant about a card charge or a loan.
- A thumbs up or down, with an optional comment, is sent to LangSmith as feedback on that exact run.
- An automation rule picks up runs with negative feedback.
- They land in an annotation queue, where support leads read the trace and write the correct answer.
- Corrected examples are added to a dataset.
- An online evaluator also scores a sample of live traffic for accuracy and policy, feeding the same rule.
- Before each release the dataset runs as a regression test, so a fixed mistake stays fixed.
Tech stack
- LangSmith feedback API
- Automation rules
- Annotation queues
- Datasets
- Online evaluators
- Pre-release regression experiments
Key design decisions
- Feedback is attached to the exact run ID, so reviewers see the full trace behind a thumbs-down.
- Rules send negative feedback and low evaluator scores to an annotation queue automatically.
- Corrected answers become dataset examples and run before every release.
Common mistakes
- Collecting feedback that is never reviewed.
- Feedback not linked to the run, so the cause cannot be found.
- Storing customers' personal details in datasets without masking.
What to measure
- Thumbs-down rate over time
- Time from feedback to correction
- Dataset size and coverage
- Regressions caught before release
Most-asked interview questions
Subjective questions 32
1Design a loop that turns customer feedback into regression tests.Asked almost every time
Capture explicit feedback (thumbs, comments) and implicit signals (retries, escalations) linked to run IDs. Automation rules send negative or flagged runs to an annotation queue where reviewers write corrected answers. Corrected examples join a regression dataset with tags. Every prompt, model or code change runs against it in CI, and releases are blocked when previously fixed cases fail again.
2What implicit feedback signals are useful?Asked almost every time
Users rephrasing the same question, regenerating answers, copying an answer (a positive signal), abandoning the session, escalating to a human, editing generated content heavily, or following up with 'that's wrong'.
3How do you prioritise which feedback to act on?Asked almost every time
Group feedback by topic or failure type, weigh by frequency, user impact and business value, and fix the clusters that affect the most users or the most important flows first.
4How do you turn user feedback into improvements?Very often asked
Log feedback against the run ID, route negative or low-scored runs to an annotation queue, have experts write the correct answer and label the failure type, add the corrected examples to a dataset, fix the prompt, retrieval or tools, and run the dataset as a regression test before every release.
5What are online evaluators?Very often asked
Evaluators that run automatically on a sample of live production traces, scoring things like correctness, safety or policy compliance without waiting for user feedback. They catch problems most users never report.
6How do you write corrected reference answers?Very often asked
Have domain experts write what the ideal answer should contain (key facts, required caveats, format), not necessarily exact wording, so evaluators can judge new answers against the criteria.
7How do you avoid the regression dataset growing stale?Very often asked
Review examples periodically, retire ones whose source facts changed, update references when policies change, and keep tags with dates and sources.
8How do online evaluators complement user feedback?Very often asked
Most users never give feedback; online evaluators score a sample of all traffic for quality signals like relevance and faithfulness, catching problems users do not report.
9How do you design the feedback UI?Very often asked
Make it one click (thumbs up or down) with an optional reason list and comment, ask at the right moment, and never interrupt the user's task.
10How do you link feedback to the right run?Very often asked
Return the run or trace ID with each response, send it back with the feedback, and store it with create_feedback, so reviewers see the exact inputs, retrieved context and outputs.
11How do you verify that a fix actually worked?Very often asked
Add the failing case to the regression dataset, run the experiment before and after the fix, confirm the case passes and that other cases did not regress, then watch production feedback on that topic.
12What should reviewers record in the annotation queue?Very often asked
Whether the answer was correct, the failure category (retrieval, reasoning, tone, outdated data), the corrected answer or criteria, and whether it should join the regression set.
13How does the online-to-offline feedback loop work in LangSmith?Very often asked
Online evaluators and user feedback flag poor production runs. You add those failing traces to a dataset, create targeted evaluators, validate the fix with an offline experiment on that dataset, then redeploy, so every real failure becomes a regression test.
Sourced from Docs by LangChain (MCP)
14How do single-run annotation queues help build datasets?Very often asked
Reviewers go through one run at a time against rubric items, which suits triaging issues and building datasets from production traces. Annotated runs can be exported directly to datasets, and single-run queues also support assertions, free-form acceptance criteria an offline evaluator can grade future runs against.
Sourced from Docs by LangChain (MCP)
15Why is user feedback alone not enough?Often asked
Few users give it, and those who do are not representative; some bad answers look convincing, so nobody complains. Combine feedback with online evaluators and regular reviews of sampled traces.
16How do you handle feedback that is wrong or malicious?Often asked
Treat feedback as a signal, not truth: reviewers verify before changing datasets, and abusive or spam feedback is filtered.
17How do you measure the loop's effectiveness?Often asked
Track negative feedback rate over time, time from feedback to fix, regression dataset size and pass rate, and repeat occurrences of fixed issues.
18How do you protect privacy in feedback data?Often asked
Mask personal data in traces and examples, get consent where required, restrict access to reviewers and apply retention limits.
19How do automation rules reduce manual work?Often asked
They filter traces by feedback score, evaluator results or metadata and automatically add them to queues or datasets, so reviewers only see relevant runs.
20How should the regression dataset be organised?Often asked
Tag examples by product area, failure category, source (feedback, audit, synthetic) and date, so experiments can be broken down by slice.
21Why not retrain the model on raw feedback?Often asked
Raw feedback is noisy, biased and sometimes wrong; curated corrections and evaluations improve systems more safely, and most fixes come from prompts, retrieval or tools rather than training.
22How do you close the loop with users?Often asked
When a reported issue is fixed, optionally tell affected users, show release notes, and thank users for feedback to encourage more.
23How often should the regression suite run?Often asked
On every change in CI for important flows and nightly for the full suite, with results tracked over time.
24How do you stop several reviewers duplicating effort on the same feedback?Often asked
Configure reservations on the annotation queue so an item is held for one reviewer for a set time, and set how many reviewers each run needs when you want independent second opinions.
Sourced from Docs by LangChain (MCP)
25What does running an online evaluator do to trace retention?Often asked
When an online evaluator runs on any run in a trace, LangSmith upgrades the trace to extended data retention. This affects trace pricing but keeps the traces that met your evaluation criteria available for investigation.
Sourced from Docs by LangChain (MCP)
26How do you use feedback to find which part of an agent is failing?Often asked
Link feedback to the run tree, then look at intermediate steps for negatively rated runs: retrieval results, tool calls and their outputs, and the final generation. Grouping failures by the step where they went wrong points to the component to fix.
27How do you balance fixing individual complaints with systemic improvements?Often asked
Cluster feedback into themes, fix urgent individual harms immediately, but prioritise work by the size and severity of each cluster, so the team improves the issues that affect most users rather than the loudest complaint.
28What is the difference between thumbs feedback and ratings?Sometimes asked
Thumbs are quick and get more responses; ratings and comments give more detail but fewer responses. Many products use thumbs with an optional reason.
29How do you report feedback trends to stakeholders?Sometimes asked
Dashboards of feedback rates by area, top failure categories, fixes shipped and their impact on negative feedback.
30How do you handle feedback on features that changed?Sometimes asked
Tag feedback with the app and prompt version, so old feedback is interpreted in context and not used to judge the new version unfairly.
31Who owns the feedback loop?Sometimes asked
A named team or person responsible for triage cadence, dataset quality and release gates, so feedback does not pile up unread.
32How do you report back to users that their feedback led to a fix?Sometimes asked
Record which feedback items each fix addressed, show a short in-product note or changelog entry when relevant, and for enterprise customers mention the improvement in account reviews.
Objective questions 32
1Which signal is implicit negative feedback?Asked almost every time
Why: Retries suggest dissatisfaction.
2Where do corrected examples end up?Asked almost every time
Why: Run them before releases.
3How should feedback be prioritised?Asked almost every time
Why: Fix the biggest clusters first.
4What should feedback be linked to?Very often asked
Why: The run ID connects the feedback to the full trace.
5Reference answers written by experts should capture…Very often asked
Why: Evaluators judge against criteria.
6Why use online evaluators as well as feedback?Very often asked
Why: They score sampled traffic.
7How should feedback be collected in the UI?Very often asked
Why: Low friction gets more responses.
8What confirms a fix worked?Very often asked
Why: Check no other regressions.
9What should reviewers record?Very often asked
Why: Categories guide fixes.
10How are stale regression examples handled?Very often asked
Why: Keep dates and sources.
11In the LangSmith loop, failing production traces are…Very often asked
Why: Real failures become regression tests.
Sourced from Docs by LangChain (MCP)
12Assertions in single-run queues are…Very often asked
Why: An offline evaluator can grade later runs against them.
Sourced from Docs by LangChain (MCP)
13Where do reviewers correct flagged answers in LangSmith?Often asked
Why: Annotation queues hold runs for people to review and label.
14Why run the corrected dataset before each release?Often asked
Why: It acts as a regression test for known failures.
15Feedback should be treated as…Often asked
Why: Some feedback is wrong.
16Which metric shows the loop is working?Often asked
Why: Fixed issues should stay fixed.
17Personal data in feedback traces should be…Often asked
Why: Privacy rules apply to feedback.
18Automation rules can…Often asked
Why: Reviewers see relevant runs.
19Regression examples should be tagged by…Often asked
Why: Enables slice analysis.
20Why not retrain directly on raw feedback?Often asked
Why: Curate and verify feedback first.
21How often should the full regression suite run?Often asked
Why: Track results over time.
22Feedback must carry which versions?Often asked
Why: Interpret it in context.
23Reservations on a queue prevent…Often asked
Why: Each item is held for one reviewer.
Sourced from Docs by LangChain (MCP)
24An online evaluator running on a trace causes…Often asked
Why: This affects trace pricing.
Sourced from Docs by LangChain (MCP)
25Annotated runs can be exported to…Often asked
Why: They become future evaluation examples.
Sourced from Docs by LangChain (MCP)
26Feedback is best prioritised by…Often asked
Why: Fixes should help the most users.
27Thumbs feedback is popular because…Sometimes asked
Why: Add optional reasons.
28Closing the loop with users means…Sometimes asked
Why: Encourages more feedback.
29Who should own the feedback loop?Sometimes asked
Why: Otherwise feedback piles up.
30Copying an answer is usually…Sometimes asked
Why: Users kept the answer.
31Stakeholder dashboards should show…Sometimes asked
Why: Show impact over time.
32To find the failing step of an agent, inspect…Sometimes asked
Why: Failures often start in retrieval or tool calls.
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