Drift Detection
How Arnold finds the gap between what your docs say and what your code does.
What is documentation drift?
Documentation drift is the gap between what you said to build and what actually got built. It happens naturally:
- Someone changes a constant but doesn't update the docs
- A feature gets descoped but the docs still describe the full version
- A new developer implements something differently than documented
- An AI coding agent builds code from a conversation that's now gone
Over time, docs and code quietly diverge. Nobody notices until something breaks.
How Arnold detects drift
When you run /arnold:check, Arnold:
- Reads all docs - Every markdown file in your
docs/folder - Extracts claims - Specific, verifiable statements like "sessions expire after 24 hours" or "maximum 20 spots per class"
- Reads all code - Source files, configs, constants, function signatures
- Matches claims to code - Finds the code that corresponds to each claim
- Reports mismatches - With file references, line numbers, and specific values
The three categories
🔴 DRIFTED
Docs say one thing, code says another. These are the critical items - an explicit mismatch between intent and implementation.
🟢 ALIGNED
Docs and code agree. Arnold found evidence in the code that matches the documented behavior.
🟡 GAPS
Something is documented but has no code (or code exists without docs). Not a conflict - just an incompleteness.
Snapshots
After each /arnold:check, Arnold creates a snapshot. This makes subsequent checks faster - only changes since the snapshot need to be analyzed. Use /arnold:diff for a quick snapshot-based check between full checks.