pijul

Patch-based version control with mathematically sound commutative patch theory.

Trit: -1 (MINUS) - Validator role for patch verification and merge correctness

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Overview

Pijul is a distributed VCS where patches are first-class citizens that commute when independent. This maps directly to:

• GF(3) skill derivation chains: patches as morphisms between skill states
• Pushouts = merges: categorical semantics for conflict resolution
• Sparsity preservation: changes stored as morphisms, not materialized states

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Installation via flox-mcp

# Using flox CLI
flox install pijul

# Via MCP (flox_install tool)
{"name": "flox_install", "arguments": {"package": "pijul"}}

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Core Commands

Repository Operations

# Initialize
pijul init

# Clone (partial clone supported!)
pijul clone https://nest.pijul.com/user/repo
pijul clone --partial https://nest.pijul.com/user/repo  # sparse clone

# Record changes (creates patch)
pijul record -m "Add feature"

# Push/Pull
pijul push
pijul pull

Patch Operations

# List patches (changes)
pijul log

# Show patch contents
pijul diff

# Apply specific patch
pijul apply <hash>

# Unapply (revert) patch
pijul unrecord <hash>

# Fork (branch)
pijul fork <name>

# Switch channel (branch)
pijul channel switch <name>

Sparse Operations

# Partial clone - only fetch needed patches
pijul clone --partial <url>

# Fetch specific patches
pijul pull --from-channel <channel>

# Lazy evaluation - patches fetched on demand
pijul reset --lazy

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Categorical Patch Theory

Patches as Morphisms

State_A --patch_1--> State_B --patch_2--> State_C
                                    
If patch_1 ⊥ patch_2 (independent):
  patch_1 ; patch_2 = patch_2 ; patch_1

Pushout for Merges

     State_A
      /   \
   p_1     p_2
    /       \
State_B    State_C
    \       /
     p_2'  p_1'
      \   /
     State_D (pushout)

When patches are independent, their pushout is unique and well-defined.

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GF(3) Integration

Sparse Mode (Default)

trit == -1 or +1: Store as morphism (patch)
  - No materialization
  - Lazy evaluation
  - Minimal storage

Projection Mode (ERGODIC Gate)

trit == 0: Force materialization
  - Coordination point
  - Full state snapshot
  - Archive checkpoint

Projection Triggers

1. --materialize

   flag explicit

2. trit == 0

   (ERGODIC coordination)
3. Explicit archive command
4. Conflict resolution requiring full state

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Skill Versioning Pattern

Record Skill Change

cd .agents/skills/my-skill
pijul record -m "Add GF(3) frontmatter"

Sync with Upstream

# Sparse pull - only new patches
pijul pull --partial

# Check for conflicts
pijul log --pending

Fork for Experimentation

pijul fork experiment
pijul channel switch experiment
# ... make changes ...
pijul record -m "Experimental patch"

# Merge back if successful
pijul channel switch main
pijul pull --from-channel experiment

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Integration with flox

Install via flox Environment

# manifest.toml
[install]
pijul.pkg-path = "pijul"

Activate and Use

flox activate
pijul --version

MCP Tool Call

{
  "name": "flox_install",
  "arguments": {"package": "pijul"}
}

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References

• Pijul Manual
• Nest (Pijul Forge)
• Mimram/Di Giusto: Categorical Patch Theory
• Delta-State CRDTs / Merkle Search Trees
• flox-mcp skill
• structured-decomp skill

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Triadic Composition

pijul (-1)  + flox-mcp (0)  + skill-creator (+1) = 0 ✓
Validator     Coordinator     Generator

Pijul validates patch correctness, flox-mcp coordinates environment, skill-creator generates new skills.

SDF Interleaving

This skill connects to Software Design for Flexibility (Hanson & Sussman, 2021):

Primary Chapter: 10. Adventure Game Example

Concepts: autonomous agent, game, synthesis

GF(3) Balanced Triad

pijul (+) + SDF.Ch10 (+) + [balancer] (+) = 0

Skill Trit: 1 (PLUS - generation)

Secondary Chapters

• Ch5: Evaluation
• Ch4: Pattern Matching

Connection Pattern

Adventure games synthesize techniques. This skill integrates multiple patterns.