MiniGit Specification
Version: 1.0
Command name: minigit
External libraries: NOT allowed
Standard library: Allowed
Persistent storage: Local filesystem only

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1. Overview
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MiniGit is a minimal version control system.

The executable must be called:

    minigit

All repository data must be stored in:

    .minigit/

All commands operate relative to current directory.

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Supported commands:

    minigit init
    minigit add <file>
    minigit commit -m "<message>"
    minigit log

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2. Repository Structure
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After init:

    .minigit/
        objects/
        commits/
        index
        HEAD

HEAD:
    latest commit hash or empty.

index:
    staged filenames (one per line).

objects/:
    blob storage.

commits/:
    commit files.

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3. Custom Hash Algorithm (MANDATORY)
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You MUST implement the following custom hash function.

Name: MiniHash

Input: raw bytes of file
Output: 16-character lowercase hexadecimal string

Algorithm:

1. Initialize:
    h = 1469598103934665603  (64-bit unsigned integer)

2. For each byte b:
    h = h XOR b
    h = (h * 1099511628211) mod 2^64

3. After processing all bytes:
    return lower 64 bits of h
    formatted as 16-character zero-padded lowercase hex

This is NOT SHA.
No crypto libraries allowed.

The exact algorithm must match this definition.

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4. Command Specifications
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4.1 init
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Create .minigit structure.

If already exists:
    print "Repository already initialized"
Exit 0.

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4.2 add <file>
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If file missing:
    print "File not found"
    exit 1

Compute MiniHash on file content.

Store blob at:
    .minigit/objects/<hash>

Append filename to index if not already present.

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4.3 commit -m "<message>"
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If index empty:
    print "Nothing to commit"
    exit 1

Commit format (exact text):

parent: <parent_hash or NONE>
timestamp: <unix_epoch_integer>
message: <message>
files:
<filename> <blobhash>
<filename> <blobhash>

Rules:
- filenames sorted lexicographically
- parent = HEAD or NONE
- commit hash = MiniHash of full commit content
- write commit file:
      .minigit/commits/<commit_hash>
- update HEAD
- clear index

Print:
    Committed <commit_hash>

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4.4 log
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If no commits:
    print "No commits"

Else traverse parents:

commit <hash>
Date: <timestamp>
Message: <message>

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5. Determinism Rules
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- Sort filenames
- No extra spaces
- No debug output
- Exact string matching required

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END
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