/icpg

name: icpg
description: Intent-Augmented Code Property Graph — tracks WHY code exists via ReasonNodes with formal contracts, 6-dimension drift detection, and 3 canonical pre-task queries for autonomous development
when-to-use: "Before any code change — query the reason graph for intent, constraints, and risk"
user-invocable: false
effort: high

iCPG Skill (Intent-Augmented Code Property Graph)

**Purpose:** Add a Reason Graph layer on top of code structure so every function, class, and module is traceable to the goal that created it, the agent or human that owns it, and whether it's still doing what it was supposed to do.

┌────────────────────────────────────────────────────────────────┐
│  iCPG = AST + CFG + PDG + RG (Reason Graph)                    │
│  ─────────────────────────────────────────────────────────────│
│  AST  = Abstract Syntax Tree (structure)      ← existing       │
│  CFG  = Control Flow Graph (execution paths)  ← existing       │
│  PDG  = Program Dependency Graph              ← existing       │
│  RG   = Reason Graph (WHY layer)              ← THIS SKILL     │
│                                                                │
│  The RG stores ReasonNodes (goals/tasks), links them to code   │
│  symbols via typed edges, enforces contracts (DbC), and        │
│  detects when code drifts from its original purpose.           │
│                                                                │
│  Storage: .icpg/reason.db (SQLite, per-project, gitignored)   │
│  CLI: icpg init | create | record | query | drift | bootstrap │
└────────────────────────────────────────────────────────────────┘

---

Core Principle

**Intent first, code second.** Before writing or modifying code, query the reason graph to understand WHY existing code was written, WHAT constraints it must preserve, and WHETHER your change duplicates prior work.

---

The 3 Canonical Pre-Task Queries

**Every agent MUST run these before writing code:**

| # | Query | Command | What It Answers | |---|-------|---------|-----------------| | 1 | **search_prior_work** | `icpg query prior "<goal>"` | Has this been attempted before? Prevents duplication. | | 2 | **get_constraints** | `icpg query constraints <file>` | What invariants apply to files I'll touch? Prevents breakage. | | 3 | **get_risk_profile** | `icpg query risk <symbol>` | Is this symbol fragile? Drift history, ownership changes. |

---

ReasonNode — The Core Primitive

Each ReasonNode captures a stated purpose with a formal contract:

id              UUID
goal            Natural language: what is this trying to achieve
decision_type   business_goal | arch_decision | task | workaround | constraint | patch
scope           Files/modules expected to be touched
owner           Human or agent accountable
status          proposed | executing | fulfilled | drifted | abandoned
source          manual | commit | inferred | agent-session

FORMAL CONTRACT (Design by Contract):
  preconditions    What must be true before this intent executes
  postconditions   What must be true when fulfilled
  invariants       What must remain true throughout and after

**Drift = predicate failure.** A symbol has drifted when its current behavior no longer satisfies the postconditions of the ReasonNode that created it, or when an invariant is violated.

---

Six Edge Types

CREATES      Reason  → Symbol   (this intent created this function)
MODIFIES     Reason  → Symbol   (this intent changed this function)
REQUIRES     Reason  → Reason   (B depends on A being done first)
DUPLICATES   Reason  → Reason   (these two goals overlap)
VALIDATED_BY Reason  → Test     (this test proves the intent was satisfied)
DRIFTS_FROM  Symbol  → Reason   (this symbol no longer does what it was made for)

---

6-Dimension Drift Model

| Dimension | What It Means | Detection | |-----------|--------------|-----------| | **Spec drift** | Symbol checksum changed without a MODIFIES edge | Compare stored vs current checksum | | **Decision drift** | Postconditions no longer hold | Evaluate predicates against codebase | | **Ownership drift** | >3 different owners without coherent oversight | Count unique owners on edges | | **Test drift** | VALIDATED_BY tests missing or failing | Check test file existence + run | | **Usage drift** | Symbol used outside original scope | Grep for imports beyond scope | | **Dependency drift** | Downstream REQUIRES reasons have drifted | Traverse REQUIRES edges |

Run `icpg drift check` to scan all dimensions. Each produces a 0-1 severity score.

---

CLI Reference

Setup

icpg init                          # Create .icpg/ and database
icpg bootstrap --days 90           # Infer ReasonNodes from git history
icpg bootstrap --days 90 --no-llm  # Without LLM (commit-message only)

Create & Record

icpg create "Add JWT auth" --scope src/auth/ --owner feature-auth --type task
icpg record --reason <id> --base main         # Record symbols from git diff
icpg record --reason <id> --edge-type MODIFIES # Record as modifications

Query (the 3 canonical queries)

icpg query prior "user authentication"     # 1. Duplicate detection
icpg query constraints src/auth/service.ts  # 2. Invariants for file
icpg query risk validateToken              # 3. Symbol risk profile
icpg query context src/auth/service.ts     # All intents for a file
icpg query blast <reason-id>               # Full blast radius

Drift

icpg drift check          # Full scan across all dimensions
icpg drift resolve <id>   # Mark drift event resolved

Status

icpg status               # Stats: reasons, symbols, edges, drift

---

Storage

Per-project, gitignored, zero infrastructure:

.icpg/
  reason.db       SQLite database (4 tables: reasons, symbols, edges, drift_events)
  .gitignore      Contains: *
  chroma/         ChromaDB vectors (if chromadb installed)
  tfidf_cache.json  TF-IDF fallback cach