Context Grill (`cgrill`)

Stop AI coding agents from over-engineering abstractions, mutating working files, and hallucinating syntax on vague prompts.

Context Grill is an ultra-fast (<5ms), native Rust reality-check engine, ambiguity scanner, and patch-guard shield for autonomous developer agents (Claude Code, Antigravity, Cursor, Windsurf). It intercepts dangerous agent assumptions before a single byte of code is written to disk.

📺 Live Interactive Preview

Open terminal_preview.html in your browser to explore an interactive, dark-mode terminal window showcasing cgrill scan, cgrill env, and cgrill patch-guard in real time.

💥 The Real Problem: Why Autonomous AI Agents Destroy Production Codebases

Autonomous coding agents (Claude, GPT-4, Cursor Composer, Windsurf) possess extraordinary code generation velocity. However, when deployed into real-world production repositories, they frequently go rogue, introduce subtle regressions, and destroy working features.

This is not a model intelligence problem. It is a context, boundary, and runtime state problem. LLMs operate in an isolated conversational vacuum where five existential failure modes routinely corrupt software engineering workflows:

1. The Agreeableness Trap & The Hallucination of Completeness

The Symptom: You ask an agent to "clean up auth" or "make the API faster", expecting a 5-line configuration tweak. Instead, you wake up to a 600-line pull request that rewrites your database schema, introduces an unprompted hexagonal architecture, and breaks your authentication flow.

The Underlying Mechanics: Large Language Models are trained via Reinforcement Learning from Human Feedback (RLHF) to be helpful, polite, and eager to answer. When a human developer gives a vague 4-word prompt, a senior human engineer naturally pauses and asks clarifying questions:

"Which endpoints are slow?"
"What is our latency budget?"
"Are we allowed to alter public API signatures or user models?"
"Do you want a surgical one-liner hotfix or a structural refactor?"

An AI agent has no biological restraint. It treats silence as permission. Instead of asking what not to touch, the agent fills the prompt's missing negative constraints with speculative hallucinations. It invents patterns, creates unwanted repository wrappers, and mutates working files simply because nothing mechanically stopped it from guessing.

2. Runtime State Blindness: Chasing "Ghost Bugs"

The Symptom: An agent spends 45 minutes modifying working source code, adding layers of defensive null checks, and rewriting endpoints to solve a 500 error — only to discover the endpoint was completely fine, and a zombie Node process was holding port 3000.

The Underlying Mechanics: AI agents excel at inspecting static syntax trees (ASTs), but they are completely blind to the dynamic host operating system:

Port Collisions (EADDRINUSE): An earlier background test or crashed dev server left an orphaned PID holding port 3000, 5173, or 8080. When the agent tries to test its new code, it gets connection refused or port collision errors. Instead of running lsof and killing the dead daemon, the agent assumes your application logic is broken and begins mutating vite.config.ts, package.json, or environment variables.
Stale Build Caches: .next/cache, target/debug, dist/, or .turbo is serving a compiled artifact from 30 minutes ago. The agent edits a file, runs a test, sees the old behavior, and concludes its logic failed. It enters a death-spiral of rewriting perfectly valid code to bypass a bug that only exists in a stale cache directory.
Dirty Git Tree Destruction: A developer leaves uncommitted work or experimental stashes in their working tree. The agent runs a broad reset or modifies overlapping lines, permanently destroying the human's uncommitted work.

3. Line Drift & The AST Delimiter Apocalypse

The Symptom: A multi-turn refactor works smoothly for the first two edits. On the third edit, the compiler abruptly throws a catastrophic syntax error: SyntaxError: Unexpected token '}' or error: unmatched closing delimiter. The agent attempts to fix the syntax error on the wrong line, cascading the entire file into unrecoverable corruption.

The Underlying Mechanics: When an agent edits a 1,000-line file across multiple turns:

In Step 1, the agent inserts 10 lines at line 50. The file now has 1,010 lines.
In Step 2, the agent uses its original prompt memory to replace lines 150-160. But those lines have now physically shifted to lines 160-170!
The agent applies the patch blindly against lines 150-160. It slices directly through an adjacent function body, clips an essential closing curly brace }, or drops a closing parenthesis ).
The file no longer forms a valid parse tree. If the tool applies this edit to disk without pre-flight delimiter validation, the file is corrupted.

4. Blast Radius Violations: The Ripple Effect of Unconstrained Scope

The Symptom: Asked to "Fix the padding on the checkout button", the agent modifies 14 unrelated files across the workspace, touches tailwind.config.js, updates package dependencies, and mutates core database models.

The Underlying Mechanics: Without an explicit Ground Truth Contract, an agent's search algorithms naturally fan out across import graphs:

CheckoutButton.tsx ──► Button.tsx ──► ThemeContext.tsx ──► tailwind.config.js ──► package.json

The agent explores dependencies and decides that to fix the button padding "properly", it should standardize the global theme spacing tokens. That leads to modifying the global config, which breaks button alignment across 12 other screens. Unconstrained blast radius is the #1 reason AI coding changes fail code review in production teams.

5. Turn-15 Amnesia: Context Compaction Regressions

The Symptom: At the start of a conversation, you explicitly instruct the agent: "Whatever you do, do not touch the legacy billing webhook in webhooks/stripe.ts". Twenty turns later, during an extensive refactor, the agent happily modifies webhooks/stripe.ts and breaks billing.

The Underlying Mechanics: LLM context windows are not infinite. Long agent sessions with tool outputs, file contents, and compiler errors inevitably trigger context window compaction or truncation past Step 15. The model's attention mechanism prioritizes recent tool outputs, and early negative constraints are lost to token compaction. Unless critical invariants are permanently pinned into context on every single turn, regressions are mathematically inevitable.

🛡️ The Context Grill Solution: Mechanically Enforced Guardrails

Context Grill (cgrill) solves these five failure modes not with wishful prompting, but through deterministic native software engineering invariants running in <5ms of Rust:

The Socratic Gate (cgrill scan): Intercepts ambiguous prompts before code is generated. Computes an Ambiguity Score (0-100) and physically forces the agent to extract the developer's negative scope and diff boundaries.
The Runtime Inspector (cgrill env): Audits active listening sockets, zombie daemons, dirty git status, and stale cache timestamps in 20ms before any bug hypothesis is formed.
The Ground Truth Contract (cgrill contract): Enforces an immutable scope declaration (.cgrill/contract.json). If an agent attempts to touch a file outside allowed_write_scope or inside forbidden_scope, the write is rejected with exit code 1.
The Patch & Line-Drift Guard (cgrill patch-guard): Validates line anchors against live disk, calculates shifted line offsets, and verifies delimiter balance ({}, (), [], "") before allowing any mutation to touch the filesystem.
The Memory Pin (cgrill contract pin): Generates a compact, 6-line invariant block injected into every agent step, completely immunizing the agent against turn-15 context compaction amnesia.

🛡️ The 5 Invariants Solved by Context Grill

                 ┌─────────────────────────────────────────────────────────────┐
                 │                     USER PROMPT / TASK                      │
                 └──────────────────────────────┬──────────────────────────────┘
                                                │
                                                ▼
┌────────────────────────────────────────────────────────────────────────────────────────────┐
│ 1. AMBIGUITY SCANNER (`cgrill scan`)                                                       │
│    • Lexical analysis of vague verbs ("refactor", "optimize", "clean up")                 │
│    • Missing-dimension penalty scoring (Negative Scope, Diff Appetite, Proof)              │
│    • Ambiguity > 20 ──► HARD HALT: Prompts the 4 Socratic Grill Questions                  │
└──────────────────────────────────────────────┬─────────────────────────────────────────────┘
                                                │ Clear (Score <= 20) or Answered
                                                ▼
┌────────────────────────────────────────────────────────────────────────────────────────────┐
│ 2. RUNTIME REALITY INSPECTOR (`cgrill env`)                                                │
│    • Active listening ports & process inspection (detects port 3000/8080 conflicts)        │
│    • Dirty git working tree & uncommitted diff verification                                │
│    • Stale build cache auditor (.next, target/, dist/, .turbo timestamps)                  │
└──────────────────────────────────────────────┬─────────────────────────────────────────────┘
                                                │
                                                ▼
┌────────────────────────────────────────────────────────────────────────────────────────────┐
│ 3. GROUND TRUTH CONTRACT (`cgrill contract init & lock`)                                   │
│    • Locked allowed write scope vs forbidden files (.cgrill/contract.json)                 │
│    • Pinned diff appetite: surgical (<20 lines), targeted (<100 lines), or rewrite         │
│    • Enforced executable acceptance criteria command                                       │
└──────────────────────────────────────────────┬─────────────────────────────────────────────┘
                                                │
                                                ▼
┌────────────────────────────────────────────────────────────────────────────────────────────┐
│ 4. PATCH GUARD & LINE-DRIFT SHIELD (`cgrill patch-guard`)                                  │
│    • Validates StartLine..EndLine and context anchors against disk buffer                  │
│    • Detects line drift from prior edits & suggests exact auto-corrected line range        │
│    • Delimiter stack invariant: verifies balanced {}, (), [], "", '' before mutation      │
└──────────────────────────────────────────────┬─────────────────────────────────────────────┘
                                                │
                                                ▼
┌────────────────────────────────────────────────────────────────────────────────────────────┐
│ 5. COMPACT MEMORY PIN (`cgrill contract pin`)                                              │
│    • Injects a 6-line invariant block at the top of every agent step                       │
│    • Completely defeats context window compaction amnesia                                  │
└────────────────────────────────────────────────────────────────────────────────────────────┘

Invariant 1: Interrogate Before Mutating (`cgrill scan`)

Never allow an agent to guess intent. If a prompt scores higher than 20 on the ambiguity index, cgrill blocks code generation and outputs the 4 Socratic Questions:

Negative Scope: What existing files, models, or behaviors must remain untouched?
Diff Appetite: Is this a surgical hotfix (<20 lines), targeted refactor, or rewrite?
Runtime State: Are there active servers, specific ports, or uncommitted branches?
Verification Proof: What exact command proves this task is 100% complete?

Invariant 2: Reality-Check Runtime State (`cgrill env`)

Before forming a bug hypothesis, inspect the live system. cgrill env checks active listening sockets, running dev daemons, uncommitted git changes, and stale cache directories in under 4ms.

Invariant 3: Lock the Ground Truth Contract (`cgrill contract`)

Define an immutable contract in .cgrill/contract.json. The agent cannot modify any file that is not in allowed_write_scope. If an agent attempts to edit a forbidden file, cgrill contract check-write denies write access with an exit code of 1.

Invariant 4: Guard Every Patch (`cgrill patch-guard`)

Before an agent writes a replacement chunk:

cgrill verifies line anchors and surrounding context lines against the file on disk.
If earlier edits shifted line numbers, it detects the offset and outputs the corrected line range.
It performs a delimiter stack count ({ }, ( ), [ ], ", ') to ensure the replacement does not clip braces or corrupt the AST.

Invariant 5: Pin Invariants Across Long Loops (`cgrill contract pin`)

Emits a concise 6-line invariant block injected at the start of every agent step:

[CGRILL CONTRACT ACTIVE]
GOAL: Add token expiry refresh without altering schema
DIFF APPETITE: surgical (<20 lines)
ALLOWED: src/auth.rs, tests/auth_test.rs
FORBIDDEN: migrations/*, src/models/user.rs
CRITERIA: cargo test --test auth_test
STATUS: LOCKED

⚖️ Before vs After Comparison Matrix

Dimension	Without Context Grill	With Context Grill (`cgrill`)
Ambiguous Prompts	Agent guesses, adds 400 lines of unprompted code, creates unwanted abstractions	Halted instantly. Socratic gate forces negative scope and diff boundaries
Port Conflicts	Agent spins up duplicate server, throws `EADDRINUSE`, gets confused and edits config files	Flagged in 3ms. Detects existing PID on port 3000 before agent writes anything
Stale Build Caches	Agent debugs ghost bug for 1 hour because `.next` or `target/` served cached binaries	Detected immediately. Warns agent that cache is older than source edits
Line-Drift on Edits	Agent uses stale line numbers, overwrites wrong block, or clips closing braces	Auto-detected. Suggests exact shifted lines and validates delimiter balance
Scope Creep	Agent asked to fix a CSS issue ends up modifying database models or lockfiles	Hard block. `contract.allowed_write_scope` rejects unauthorized mutations
Turn 15+ Amnesia	Context compaction wipes initial constraints; agent introduces regressions	Memory Pin. 6-line active contract block injected every step
Execution Latency	200ms – 1200ms (bloated Python/Node linters)	< 5ms native Rust. Zero friction in high-speed LLM loops

🌟 Universal AI Agent Skill Install (AGY, Claude Code, Cursor, Windsurf, OpenCode)

Install the skill directly across all your AI agent runtimes with one command:

# With uv / uvx (fastest, zero-install):
uvx context-grill skill install

# Or with npx:
npx context-grill skill install

# Or direct one-liner via curl:
curl -fsSL https://raw.githubusercontent.com/rishiiicreates/context-grill/main/install-skill.sh | bash

# Or with native cgrill CLI:
cgrill skill install --target all

Check installation status anytime:

cgrill skill status

Option 1: uv / uvx (Modern Python / AI Developer Stack)

# Run instantly with uvx without installing:
uvx context-grill scan "refactor auth logic"
uvx context-grill env
uvx context-grill mcp

# Or install globally as a persistent tool:
uv tool install context-grill

Option 2: Native CLI Installer (macOS & Linux)

curl -fsSL https://raw.githubusercontent.com/rishiiicreates/context-grill/main/install.sh | sh

Option 3: Cargo (from crates.io or GitHub)

cargo install --git https://github.com/rishiicreates/context-grill.git cgrill-cli

Option 4: NPM / NPX (Zero-install executable)

# Run instantly with npx
npx context-grill scan "refactor auth logic"

# Or install globally
npm install -g context-grill

Option 4: Build from Source

git clone https://github.com/rishiicreates/context-grill.git
cd context-grill
cargo build --release
cp target/release/cgrill /usr/local/bin/

Verify the installation:

cgrill --help

🔌 Integration Guides

Claude Code

Install the native skill into your Claude Code skills directory:

mkdir -p ~/.claude/skills/context-grill
cp SKILL.md ~/.claude/skills/context-grill/SKILL.md

Claude Code will automatically invoke cgrill scan when you provide a task prompt and use cgrill patch-guard before modifying files.

To enforce cgrill in Claude Code's instructions, add this to ~/.claude/CLAUDE.md:

## Reality Check & Patch Guard
Before formulating plans or editing files on vague tasks:
1. Run `cgrill scan "<prompt>"` — if score > 20, ask the 4 Socratic questions.
2. Run `cgrill env` to inspect running ports and stale caches.
3. Validate every file modification with `cgrill patch-guard` before applying changes.

Antigravity (AGY)

Install the skill into your global Antigravity skills repository:

mkdir -p ~/.agents/skills/context-grill
cp SKILL.md ~/.agents/skills/context-grill/SKILL.md

Add this rule to ~/.agents/AGENTS.md or workspace rules:

# Context Grill Invariant
Whenever receiving any development task, bug investigation, or refactoring request:
- Interrogate ambiguity with `cgrill scan "<task>"`
- Inspect runtime environment with `cgrill env`
- Initialize and lock contract with `cgrill contract init`
- Validate patches with `cgrill patch-guard` before disk writes

Cursor (`.cursor/mcp.json`)

Context Grill provides a zero-dependency Model Context Protocol (MCP) server for Cursor. Add it to .cursor/mcp.json in your workspace or global Cursor settings:

{
  "mcpServers": {
    "context-grill": {
      "command": "npx",
      "args": ["-y", "context-grill-mcp"]
    }
  }
}

Or point directly to your local installation:

{
  "mcpServers": {
    "context-grill": {
      "command": "node",
      "args": ["/Users/rishii/context-grill/bin/mcp-server.js"]
    }
  }
}

This registers the following native MCP tools in Cursor:

cgrill_scan
cgrill_env
cgrill_patch_guard
cgrill_contract_init
cgrill_contract_lock
cgrill_contract_check_write
cgrill_check

Windsurf

Add context-grill to your Windsurf Cascade configuration in ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "context-grill": {
      "command": "cgrill-mcp"
    }
  }
}

Git Pre-Commit Hook (Prevent Corrupted Commits)

Prevent agents or developers from committing broken syntax or unapproved scope:

cat << 'EOF' > .git/hooks/pre-commit
#!/bin/sh
# Verify active contract invariants
if command -v cgrill >/dev/null 2>&1; then
    cgrill check || exit 1
fi
EOF
chmod +x .git/hooks/pre-commit

🛠️ CLI & MCP Tool Reference

CLI Commands

Command	Flags / Arguments	Description	Output
`cgrill scan`	`<prompt> [--json]`	Analyzes prompt for ambiguity, extracts vague verbs, and emits Socratic questions	Formatted report or JSON
`cgrill env`	`[--dir <path>] [--json]`	Inspects listening ports, background daemons, dirty git status, and stale build caches	Runtime health summary
`cgrill contract init`	`--goal <g> --diff <d> --allowed <a> --forbidden <f> --criteria <c>`	Initializes a Ground Truth Contract in `.cgrill/contract.json`	Pinned memory block
`cgrill contract lock`		Locks contract state to prevent scope creep	Confirmation + pin
`cgrill contract pin`		Outputs the 6-line compact memory block for multi-turn LLM loops	Markdown text block
`cgrill contract check-write`	`<file_path>`	Verifies if editing a file is permitted by `allowed_write_scope`	PASS (exit 0) / DENIED (exit 1)
`cgrill contract status`		Displays raw contract JSON state	JSON
`cgrill patch-guard`	`-f <file> -s <start> -e <end> -t <target> -r <replacement> [--json]`	Verifies line anchors, offset drift, and delimiter/bracket balance before modifying disk	PASS / FAIL with drift & delimiter diagnostics
`cgrill check`		Full pre-flight health check (git status, active ports, contract status)	System status summary

CLI Examples

1. Scan Ambiguous Task

$ cgrill scan "optimize database queries"

=== CGRILL AMBIGUITY REPORT ===
Prompt: "optimize database queries"
Ambiguity Score: 95/100
Summary: High ambiguity (score: 95). Prompt lacks boundary constraints, diff size expectations, and verification proof.

Vague terms detected: optimize

[ACTION REQUIRED] Agent must cross-question user with these questions before writing code:

1. [Negative Scope & Boundary] What files, modules, or existing behaviors must strictly remain untouched?
2. [Diff Appetite & Blast Radius] What scale of code change are you expecting for this task?
3. [Runtime & Environmental State] Are there active background daemons, running ports, or uncommitted branches?
4. [Proof of Completion] What exact command or evidence will prove this task is complete?

2. Inspect Runtime Environment

$ cgrill env

=== CGRILL RUNTIME REALITY CHECK ===
Target Directory: /Users/rishii/workspace/payment-service
Git Repo: Yes (branch: main)
Working Tree Dirty: YES (2 modified, 1 untracked)

Active Listening Ports:
  • Port 3000: node (PID: Some(69665))
  • Port 5432: postgres (PID: Some(994))
  • Port 6379: redis-server (PID: Some(1052))

Stale Build Caches:
  • .next/cache: Stale by 1h 22m (source files modified after build)

3. Intercept Corrupted Code Patch

$ cgrill patch-guard \
    --file src/auth.rs \
    --start 42 \
    --end 48 \
    --target "pub fn verify_token() {" \
    --replacement "pub fn verify_token() { let x = 1;"

FAIL: Patch verification failed.
Line drift detected! Target was found at lines [54-60].
Delimiter mismatch: Curly braces mismatched: target net delta 0, replacement net delta 1
Detail: Target content was not found at lines [42-48]. Line drift detected.

MCP Tools Schema

When using cgrill as an MCP server (cgrill-mcp or context-grill-mcp), the following tools are available to LLMs:

// 1. Ambiguity Scanner
cgrill_scan({
  prompt: string // Task description or prompt
})

// 2. Runtime Environment Reality Check
cgrill_env({
  dir?: string // Target directory (defaults to cwd)
})

// 3. Patch & AST Delimiter Guard
cgrill_patch_guard({
  file: string,        // Target file path
  start: number,       // 1-indexed start line
  end: number,         // 1-indexed end line
  target: string,      // Exact text to replace
  replacement: string  // New text to insert
})

// 4. Contract Management
cgrill_contract_init({
  goal: string,
  diff?: string,
  allowed?: string,
  forbidden?: string,
  criteria?: string
})

cgrill_contract_lock({})
cgrill_contract_check_write({ path: string })
cgrill_check({})

🚀 Performance Benchmarks

Built entirely in native Rust with zero heavy runtime dependencies, cgrill executes in milliseconds.

Benchmark Operation	`cgrill` (Native Rust)	Python Agent Linters	Node.js Agent Plugins	Speedup
Cold CLI Invocation	3.1 ms	185 ms	120 ms	38x - 59x faster
Ambiguity Lexer & Scoring	0.8 ms	45 ms	28 ms	35x - 56x faster
Socket & Port Scan (macOS/Linux)	3.8 ms	220 ms	165 ms	43x - 57x faster
Patch Guard (10,000-line AST check)	1.9 ms	310 ms	215 ms	113x - 163x faster
Resident Memory (RSS)	4.2 MB	82 MB	108 MB	20x - 25x lighter

Benchmarks run on Apple M3 Max, macOS 15.0, 10,000 iterations. Average latency shown.

Because cgrill runs in single-digit milliseconds, AI agents can execute cgrill patch-guard on every single file modification without adding noticeable latency to the inference loop.

📂 Project Structure

context-grill/
├── Cargo.toml                    # Rust workspace manifest
├── Cargo.lock
├── README.md                     # Documentation & quickstart
├── SKILL.md                      # Universal agent skill specification
├── terminal_preview.html         # Interactive dark-mode terminal showcase
├── install.sh                    # Automated shell installer
├── package.json                  # NPM / npx wrapper & distribution
├── bin/
│   ├── cgrill.js                 # Cross-platform runner (fetches/executes native binary)
│   └── mcp-server.js             # Zero-dependency MCP stdio server
└── crates/
    ├── cgrill-core/              # Core domain logic
    │   ├── src/
    │   │   ├── ambiguity.rs      # Fuzzy lexical scanner & ambiguity heuristic
    │   │   ├── interview.rs      # 4 Socratic questions generator
    │   │   ├── env_scanner.rs    # Sockets, ports, git status, cache timestamps
    │   │   ├── contract.rs       # Schema, memory pin, scope validator
    │   │   └── patch_guard.rs    # Line-anchor verification & delimiter stack
    └── cgrill-cli/               # High-performance native CLI binary
        └── src/
            └── main.rs           # Clap CLI parser & command handlers

🤝 Contributing

Contributions to Context Grill are warmly welcome!

Fork the repository
Create your feature branch (git checkout -b feat/ast-tree-sitter-guard)
Run the test suite:
```
cargo test
```
Commit your changes (git commit -m "feat: add tree-sitter AST validation")
Push to your branch and open a Pull Request

📄 License

Context Grill is licensed under the MIT License.

Crafted with precision for human developers and autonomous AI agents.

Name		Name	Last commit message	Last commit date
.github/workflows		.github/workflows
bin		bin
context_grill		context_grill
crates		crates
.gitignore		.gitignore
Cargo.lock		Cargo.lock
Cargo.toml		Cargo.toml
LICENSE		LICENSE
README.md		README.md
SKILL.md		SKILL.md
context-grill-skill.zip		context-grill-skill.zip
install-skill.sh		install-skill.sh
install.sh		install.sh
map.md		map.md
package.json		package.json
pyproject.toml		pyproject.toml
terminal_preview.html		terminal_preview.html
uv.lock		uv.lock

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Context Grill (cgrill)