diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index b09f6ff..bb9e363 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -1,102 +1,128 @@
+```bash
 # Clone the repository
+git clone https://github.com/hyperpolymath/refugia.git
+cd refugia
 
-git clone <https://github.com/hyperpolymath/refugia.git> cd refugia
-
-# Using Nix (recommended for reproducibility)
-
-nix develop
+# Using Guix (recommended for reproducibility)
+guix shell
 
 # Or using toolbox/distrobox
-
-toolbox create refugia-dev toolbox enter refugia-dev \# Install
-dependencies manually
+toolbox create refugia-dev
+toolbox enter refugia-dev
+# Install dependencies manually
 
 # Verify setup
+just must-check    # Required repository invariants
+just trust-verify  # Repository trust checks
+```
+
+## Repository Structure
+
+```text
+refugia/
+├── src/ # Source code (Perimeter 1-2)
+├── lib/ # Library code (Perimeter 1-2)
+├── extensions/ # Extensions (Perimeter 2)
+├── plugins/ # Plugins (Perimeter 2)
+├── tools/ # Tooling (Perimeter 2)
+├── docs/ # Documentation (Perimeter 3)
+│   ├── architecture/ # ADRs, specs (Perimeter 2)
+│   └── proposals/ # RFCs (Perimeter 3)
+├── examples/ # Examples (Perimeter 3)
+├── spec/ # Spec tests (Perimeter 3)
+├── tests/ # Test suite (Perimeter 2-3)
+├── .well-known/ # Protocol files (Perimeter 1-3)
+├── .github/ # GitHub config (Perimeter 1)
+│   ├── CONTRIBUTING.md # This file
+│   ├── ISSUE_TEMPLATE/
+│   └── workflows/
+├── CHANGELOG.md
+├── CODE_OF_CONDUCT.md
+├── GOVERNANCE.md
+├── LICENSE
+├── MAINTAINERS.md
+├── README.adoc
+├── SECURITY.md
+├── flake.nix # Nix flake (Perimeter 1)
+└── Justfile # Task runner (Perimeter 1)
+```
 
-just check \# or: cargo check / mix compile / etc. just test \# Run test
-suite
-
+    ---
 
-    ### Repository Structure
+## How to Contribute
 
-refugia/ ├── src/ \# Source code (Perimeter 1-2) ├── lib/ \# Library
-code (Perimeter 1-2) ├── extensions/ \# Extensions (Perimeter 2) ├──
-plugins/ \# Plugins (Perimeter 2) ├── tools/ \# Tooling (Perimeter 2)
-├── docs/ \# Documentation (Perimeter 3) │ ├── architecture/ \# ADRs,
-specs (Perimeter 2) │ └── proposals/ \# RFCs (Perimeter 3) ├── examples/
-\# Examples (Perimeter 3) ├── spec/ \# Spec tests (Perimeter 3) ├──
-tests/ \# Test suite (Perimeter 2-3) ├── .well-known/ \# Protocol files
-(Perimeter 1-3) ├── .github/ \# GitHub config (Perimeter 1) │ ├──
-ISSUE_TEMPLATE/ │ └── workflows/ ├── CHANGELOG.md ├── CODE_OF_CONDUCT.md
-├── CONTRIBUTING.md \# This file ├── GOVERNANCE.md ├── LICENSE ├──
-MAINTAINERS.md ├── README.adoc ├── SECURITY.md ├── flake.nix \# Nix
-flake (Perimeter 1) └── Justfile \# Task runner (Perimeter 1)
+### Reporting Bugs
 
+**Before reporting**:
 
-    ---
+1. Search existing issues
+2. Check if it's already fixed in `main`
+3. Determine which perimeter the bug affects
 
-    ## How to Contribute
+**When reporting**:
 
-    ### Reporting Bugs
+Use the [bug report template](.github/ISSUE_TEMPLATE/bug_report.md) and include:
 
-    **Before reporting**:
-    1. Search existing issues
-    2. Check if it's already fixed in `main`
-    3. Determine which perimeter the bug affects
+- Clear, descriptive title
+- Environment details (OS, versions, toolchain)
+- Steps to reproduce
+- Expected vs actual behaviour
+- Logs, screenshots, or minimal reproduction
 
-    **When reporting**:
+### Suggesting Features
 
-    Use the [bug report template](.github/ISSUE_TEMPLATE/bug_report.md) and include:
+**Before suggesting**:
 
-    - Clear, descriptive title
-    - Environment details (OS, versions, toolchain)
-    - Steps to reproduce
-    - Expected vs actual behaviour
-    - Logs, screenshots, or minimal reproduction
+1. Check the [roadmap](ROADMAP.md) if available
+2. Search existing issues and discussions
+3. Consider which perimeter the feature belongs to
 
-    ### Suggesting Features
+**When suggesting**:
 
-    **Before suggesting**:
-    1. Check the [roadmap](ROADMAP.md) if available
-    2. Search existing issues and discussions
-    3. Consider which perimeter the feature belongs to
+Use the [feature request template](.github/ISSUE_TEMPLATE/feature_request.md) and include:
 
-    **When suggesting**:
+- Problem statement (what pain point does this solve?)
+- Proposed solution
+- Alternatives considered
+- Which perimeter this affects
 
-    Use the [feature request template](.github/ISSUE_TEMPLATE/feature_request.md) and include:
+### Your First Contribution
 
-    - Problem statement (what pain point does this solve?)
-    - Proposed solution
-    - Alternatives considered
-    - Which perimeter this affects
+Look for issues labelled:
 
-    ### Your First Contribution
+- [`good first issue`](https://github.com/hyperpolymath/refugia/labels/good%20first%20issue) — Simple Perimeter 3 tasks
+- [`help wanted`](https://github.com/hyperpolymath/refugia/labels/help%20wanted) — Community help needed
+- [`documentation`](https://github.com/hyperpolymath/refugia/labels/documentation) — Docs improvements
+- [`perimeter-3`](https://github.com/hyperpolymath/refugia/labels/perimeter-3) — Community sandbox scope
 
-    Look for issues labelled:
+---
 
-    - [`good first issue`](https://github.com/hyperpolymath/refugia/labels/good%20first%20issue) — Simple Perimeter 3 tasks
-    - [`help wanted`](https://github.com/hyperpolymath/refugia/labels/help%20wanted) — Community help needed
-    - [`documentation`](https://github.com/hyperpolymath/refugia/labels/documentation) — Docs improvements
-    - [`perimeter-3`](https://github.com/hyperpolymath/refugia/labels/perimeter-3) — Community sandbox scope
+## Development Workflow
 
-    ---
+### Branch Naming
 
-    ## Development Workflow
+```text
+docs/short-description       # Documentation (P3)
+test/what-added              # Test additions (P3)
+feat/short-description       # New features (P2)
+fix/issue-number-description # Bug fixes (P2)
+refactor/what-changed        # Code improvements (P2)
+security/what-fixed          # Security fixes (P1-2)
+```
 
-    ### Branch Naming
 
-docs/short-description \# Documentation (P3) test/what-added \# Test
-additions (P3) feat/short-description \# New features (P2)
-fix/issue-number-description \# Bug fixes (P2) refactor/what-changed \#
-Code improvements (P2) security/what-fixed \# Security fixes (P1-2)
+### Commit Messages
 
+We follow [Conventional Commits](https://www.conventionalcommits.org/):
 
-    ### Commit Messages
+```text
+type(scope): description
 
-    We follow [Conventional Commits](https://www.conventionalcommits.org/):
+Body: what changed and why.
 
-():
+Footer: issue reference, e.g. Closes #123
 
-\[optional body\]
+[optional body]
 
-\[optional footer\]
+[optional footer]
+```