45 lines
1.7 KiB
Markdown
45 lines
1.7 KiB
Markdown
---
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epic: 3
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story: 3.3
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title: "Historical Rates"
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status: draft
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---
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## Epic 3 — Currency & Cryptocurrency
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**Goal:** Real-time and historical currency conversion with 180+ fiat and 50+ crypto.
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### Story 3.3: Historical Rates
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As a CalcPad user,
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I want to convert currencies using historical exchange rates on specific dates,
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So that I can calculate what an amount was worth at a particular point in time.
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**Acceptance Criteria:**
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**Given** the expression `$100 in EUR on 2024-01-15`
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**When** the engine evaluates it
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**Then** it fetches (or uses cached) the EUR/USD rate from January 15, 2024
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**And** the result reflects the historical conversion
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**Given** historical rates for a specific date have been fetched before
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**When** the same date is queried again
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**Then** the cached historical rates are used without a network call
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**Given** a historical rate result
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**When** the result is displayed
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**Then** the metadata clearly indicates "historical rate from [date]"
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**And** it is visually distinct from live rate results
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**Given** the expression `$100 in EUR on 1900-01-01` (a date before available data)
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**When** the engine evaluates it
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**Then** it returns a `CalcResult::Error` indicating historical rates are not available for that date
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**Given** the device is offline and no cached historical rate exists for the requested date
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**When** a historical conversion is requested
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**Then** the engine returns a `CalcResult::Error` indicating the historical rate is not available offline
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**Given** the expression `€500 in GBP on March 5, 2023`
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**When** the engine evaluates it
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**Then** it correctly parses the natural-language date format
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**And** fetches the historical rate for 2023-03-05
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