Feature: add /history endpoint to retrieve past calculations

[ascerra]

Description

There's no way to see previously computed results. Add a /history endpoint that returns the last N calculations performed.

Proposed behavior

GET /history         → returns last 10 calculations
GET /history?limit=5 → returns last 5

Response format:

[
  {"operation": "add", "a": 2, "b": 3, "result": 5, "timestamp": "2026-06-01T12:00:00Z"},
  {"operation": "multiply", "a": 4, "b": 5, "result": 20, "timestamp": "2026-06-01T12:01:00Z"}
]

Acceptance criteria

• Store calculations in memory (no database needed)
• Default limit of 10, max 100
• Include timestamp for each entry

[enxebre]

/fs-triage

[fullsend-ai-triage]

Triage Summary

Category: Feature request · Severity: Low

This is a well-specified feature request for a GET /history endpoint that returns past calculation results stored in memory.

Problem

The API currently has no way to retrieve previously computed results.

Recommended Implementation

1. Add a module-level list to store calculation history entries.
2. In each calculation endpoint (add, multiply, divide, etc.), append a record containing the operation name, operands, result, and UTC timestamp.
3. Create a GET /history route accepting an optional ?limit query parameter (default 10, max 100) that returns the most recent entries as JSON.

Proposed Test Case

- GET /history on a fresh server returns []
- POST several calculations, then GET /history returns matching entries
- Each entry contains: operation, a, b, result, timestamp (ISO 8601)
- ?limit=5 returns at most 5 entries
- Default limit is 10; values above 100 are capped to 100
- Entries are ordered most-recent-first

The acceptance criteria in the issue are clear and complete. Ready for implementation.

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Labels: This is a new feature request for an API endpoint, matching the enhancement label.