pmarreck

MFIC — Mechanically-Falsifiable Independent Control

A discipline for tests and runtime checks that can't be fooled by the same mistake that produced the code.

How to trust code or data when a fallible author (an LLM or a human) could quietly corrupt it. TDD's red phase proves a test can fire — that is the F alone; MFIC adds the other three axes. Framing: internal control over a production process that now includes a powerful, fallible, confident actor — the COSO / Sarbanes-Oxley internal-control model, with an LLM (or a hurried human) as the new untrusted party.

Definition: an independent check at a handoff boundary that derives what it verifies from the contract or the data itself — never from the producer's account of it — turns each handoff into a refutation that bites, and holds the authority to reject, halt, or steer the flow.

Litmus: if the same agent wrote both the check and the thing checked, could it pass with wrong work? Yes → gameable, not MFIC. No → MFIC.

pmarreck

Jujutsu (jj) Quick Reference (For Users and Agents)

For Git Users: The Mental-Model Shifts

The command-translation table below is necessary but not sufficient. A few git assumptions don't carry over — internalize these and the rest of jj stops looking weird.

1. No staging area. Your working copy IS a commit (the @ commit). Every jj command auto-snapshots it. There's no add step and no index. When done, jj commit -m finalizes it and opens a fresh empty one. To split changes (the git add -p workflow), commit everything and then jj split.

2. Commits have two IDs: change_id (stable) and commit_id (mutates). In git, rewriting (rebase, amend) creates brand-new SHAs and the originals fall into reflog. In jj, the change_id is a stable identity that persists through rewrites — only the commit_id (the Git SHA equivalent) changes. Bookmarks and references survive rebases/squashes by tracking the change_id. jj evolog shows every prior commit_id of one change_id.

pmarreck

name	dispatch
description	Use when dispatching one or more background subagents to do a substantial task, especially when fanning out parallel work. Injects a standard discipline preamble so agents keep externalized progress state (survives turn-budget cutoffs), use correct harness wait patterns, avoid stomping on peer agents, and always write a final report — even if incomplete.

Dispatch

Wraps subagent dispatch with a standard discipline preamble. The goal is that any agent you fan out, whether one or five, behaves predictably: it keeps state externalized, fails honestly, and leaves a trail even if cut off.

pmarreck

# Zig API Reference for 2025 (0.14.0 - 0.15.x)

Purpose: Quick reference for LLMs and developers writing fresh Zig code in 2025. Focus on "how to do things correctly now" rather than migration from old APIs.

Current Version: Zig 0.15.x (as of late 2025)

Sources:

• Zig 0.15.1 Release Notes
• Zig 0.14.0 Release Notes

pmarreck

Jujutsu (jj) Quick Reference

Basic Operations

Commits

# Update the description of the current change and create a new empty change on top
jj commit -m "Commit message"

# Edit the description of the current commit

pmarreck

Agent Briefing

Bit about me: <redacted personal info that is easily googleable anyway lol>

Your role: Functional, TDD-first, curiosity-prodding developer who balances correctness, performance, and clarity. Act as a precise pair programmer; when tradeoffs arise, list brief pros/cons and pause for direction.

Important: Refer to me as "Peter" in conversation, not "the user".

Curiosity cue: after each reasoning step, ask yourself: “What am I missing? What are the alternative designs? What could break, or be broken into? How might this be simpler or more concise?”

Work Rhythm

pmarreck

diff --git a/erts/emulator/beam/copy.c b/erts/emulator/beam/copy.c
index e09a2ab51c6..6487f830794 100644
--- a/erts/emulator/beam/copy.c
+++ b/erts/emulator/beam/copy.c
@@ -1589,9 +1589,8 @@ Uint copy_shared_perform_x(Eterm obj, Uint size, erts_shcopy_t *info,
                 switch (MAP_HEADER_TYPE(hdr)) {
                     case MAP_HEADER_TAG_FLATMAP_HEAD : {
                         flatmap_t *mp = (flatmap_t *) ptr;
-                        Uint n = flatmap_get_size(mp);
-                        ASSERT(n <= MAP_SMALL_MAP_LIMIT);

pmarreck

# I got tired of this pattern: mkdir -p path/to/dir && cd path/to/dir
# So now mkdir will take a -c or --cd argument to do it all at once.

mkdir-custom () {
  local do_cd=false;
  local mkdir_args=();
  local target_dir="";
  function show_help ()
  {
    cat <<-'EOF'

pmarreck

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Asteroids Game</title>
    <style>
        * {
            margin: 0;

pmarreck

local ffi = require("ffi")
local bit = require("bit")
ffi.cdef([[  struct winsize {
    unsigned short ws_row;
    unsigned short ws_col;
    unsigned short ws_xpixel;
    unsigned short ws_ypixel;
  };

  int ioctl(int fd, unsigned long request, ...);