# MurphySig — Provenance for AI-Assisted Work > Drop this into your `CLAUDE.md` / `AGENTS.md` (or import it) so AI collaborators > sign their work. MurphySig is a human-readable provenance convention — no tooling > required. Full spec: https://murphysig.dev/spec When you create or significantly modify a file, add a MurphySig block. ## The signature A comment block at the top of the file (after any shebang or package declaration), in the file's own comment syntax: ``` # Signed: + , # Format: MurphySig v0.4 (https://murphysig.dev/spec) # Context: # Confidence: <0.0-1.0 or honest text> - # Open: ``` Use your **precise** model identifier — `claude-opus-4-8`, not "Claude"; `gpt-5.4`, not "GPT". Models change every ~90 days; the version is the point. Example: ```python # Signed: Kev Murphy + claude-opus-4-8, 2026-06-24 # Format: MurphySig v0.4 (https://murphysig.dev/spec) # Context: In-memory pagination helper, written during a service migration. # Confidence: 0.5 - standard pattern, not validated on edge cases. # Open: Does page > total_pages behave correctly, or silently return empty? ``` ## What actually carries the value The point isn't the format — it's the **act of writing down what you know and what you're unsure about**. The `Context:`, `Confidence:`, and `Open:` fields capture the tacit knowledge that lives in your head and never reaches the code. Empirically, that transferred knowledge is what helps the next reader (human or AI); the structure is a completeness scaffold, not magic. So fill those fields like they matter — because they are the thing that matters. (See https://murphysig.dev/benchmark.) ## When modifying a signed file 1. **Read the existing signature first** — understand intent and confidence before changing anything. 2. **Add a `Reviews:` entry** for incremental changes (don't replace the original `Signed:` block): ``` # Reviews: # - , : . Confidence now . ``` 3. **Replace the signature** (with a `Prior:` reference) only if you rewrote >50% of the file. ## Rules - **Never fabricate provenance.** If a file has no signature and you modify it, sign only your own contribution with `Prior: Unknown`. Do not invent authors, dates, or collaborator models you weren't part of. (Empirically: with this rule in-context, AI fabrication of provenance drops to ~0.) - **Be honest about confidence.** "Sketchy — first time with this library" beats a made-up `0.7`. - **Credit the human too.** If a person directed the work, they're a co-author.