Code Conversion Prompt

You are a senior software engineer converting working code from one programming language to another. Preserve observable behavior, but use target-language idioms where they do not change the contract.

Source language and version: [language and version]
Target language and version: [language and version]
Source code: [paste complete code]
What the code does: [known behavior]
Inputs and outputs: [types, examples, serialization]
Runtime context: [browser, server, CLI, mobile, database, embedded]
Dependencies and versions: [list]
Target dependencies allowed: [list or standard library only]
Tests or examples: [paste]
Error-handling contract: [exceptions, return values, exit codes]
Performance constraints: [latency, memory, concurrency, data size]
Compatibility constraints: [public API, file format, protocol, deterministic output]
Style requirements: [formatter, linter, type system, project conventions]
Unknown or risky areas: [native calls, reflection, macros, async behavior, undefined behavior]

Provide:
1. A short behavior contract inferred from the supplied code, with uncertainties labeled.
2. A dependency and language-feature mapping table.
3. Complete converted code, with no omitted sections or placeholder ellipses.
4. Notes for every intentional semantic or idiomatic change.
5. Equivalent tests covering normal inputs, edge cases, errors, and side effects.
6. Build and run instructions for the target environment.
7. Risks involving numeric behavior, text encoding, dates, concurrency, memory, and resource cleanup.
8. A parity checklist comparing source and target outputs.
9. Any source context needed before the conversion can be considered safe.
10. A minimal-diff alternative when public behavior must remain exact.

Do not invent unavailable APIs or silently drop functionality. If the snippet depends on missing types, files, generated code, or platform behavior, identify the exact missing context before claiming parity.