Case studyIllustrative write-up · no real client
Answers from private documents, with sources shown
An experiment in retrieval-based question answering where every answer can be checked.
- Client
- None: illustrative
- Industry
- Internal experiment
- Screens from
- Paperlane (concept)


01Challenge
The problem, as it was found
Useful answers existed in a set of private documents, but finding them meant searching files by hand, and a plain chatbot could not be trusted to stay faithful to them.
- Answers were buried across many documents
- A general-purpose assistant could state things the documents did not say
- Users needed to see where an answer came from
- The document set changed over time
Context
This was a prototype to understand what retrieval over private documents does well and where it fails, before recommending it to anyone.
The working rule was that an answer without a visible source was treated as a failure, however fluent it sounded.
02System
How it was put together
L1 · Ask and verify
Interface
- Question box
- Answer
- Source panel
L2 · Find, then answer
Retrieval
- Passage search
- Ranking
- Source tracking
L3 · Constrained generation
Model
- AI / LLM integration
- Prompt rules
L4 · Keeps the index current
Ingestion
- Splitting
- Embeddings
- Re-indexing
Path through the system
- 1Question asked
- 2Passages retrieved
- 3Answer drafted from passages
- 4Sources shown
- 5Answer reviewed
03What was built
The parts, in the order they shipped
- 01
Ingestion
Documents are split into passages and indexed, and re-indexed when they change.
- 02
Retrieval
A question finds the most relevant passages before any text is generated.
- 03
Answer with sources
The assistant answers from the retrieved passages and shows which ones it used.
- 04
Review view
A way to compare answers with their sources and note where they fell short.


04Decisions
The choices that shaped it
Decision 1
No source, no answer
Why
An answer that cannot be traced is not useful in a setting where accuracy matters.
Trade-off
The assistant declines more often than a general chatbot.
Decision 2
Evaluate on real questions
Why
Quality can only be judged against the questions people actually ask.
Trade-off
It meant collecting examples first, before tuning anything.
Decision 3
Keep a person in the loop
Why
Retrieval narrows the risk but does not remove it.
Trade-off
Slower than a fully automated flow, and more trustworthy.
05Technology
What it was built with
- Backend
- Node.jsExpress.jsREST APIs
- Database
- PostgreSQL
- Cloud and DevOps
- Docker
- AI and automation
- AI / LLM IntegrationsRAG
06Outcome
Showed where retrieval-based answering is reliable, and where it still needs a person to check.
- Every answer links back to the passages behind it
- Questions outside the documents are declined rather than guessed
- The experiment informed how we scope retrieval projects
Demo case study. Outcomes are qualitative. No metrics, savings, revenue or user figures are claimed.
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