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Document-Code Mode

Use this mode to retro-document an existing codebase. The agent scans your files and generates C4 diagrams from what it finds — no design dialogue required.

When it activates​

  • You paste or reference a code snippet
  • You say "here's my codebase" or provide a repo path
  • "Retro-document this codebase"

How to trigger it​

Option 1: Paste relevant files

Act as the C4 Designer. Please retro-document this system and generate
a Level 2 Container Diagram.

[paste contents of package.json, docker-compose.yml, index.js, etc.]

Option 2: Point to a directory (agents that can read the filesystem)

Act as the C4 Designer. Scan the src/ directory and generate
a Level 2 Container Diagram.

What the agent scans​

The agent looks for these signals:

FileWhat it reveals
package.json, pom.xml, requirements.txtTechnology stack, key dependencies
docker-compose.yml, DockerfileContainer boundaries, environment vars
*.env.example, config/*.ymlExternal services (DBs, queues, APIs)
Route files, controller filesAPI surface area
Import/require statementsInter-module dependencies

Expected output​

The agent produces a Markdown file with:

  1. Level 1 Context diagram — system + actors + external systems inferred from config
  2. Level 2 Container diagram — services, databases, queues identified from code
  3. Assumptions section — anything guessed, not found explicitly in the code
  4. Key relationships table — source, destination, inferred protocol

Complex Input: Monorepo​

For large monorepos, prompt the agent to focus:

Act as the C4 Designer in Document-Code mode. Focus only on the
services/payments/ directory. Ignore the frontend/ directory.
Generate a Level 3 Component Diagram for the payments service.

Limitations & exceptions​

caution

The agent cannot execute code. It infers architecture from static analysis only.

If a service dynamically discovers other services (e.g., via Kubernetes service mesh or a service registry), the agent cannot infer these connections. You must tell it explicitly.

note

If the codebase is very large (50+ files), the agent will ask you to focus on specific files rather than scanning everything at once.