Claude Code Signs Your Commits. Which Setting Actually Stops It?
The top search result tells you to set includeCoAuthoredBy to false. That key is deprecated, and the replacement has three traps in it. I measured 88 runs to find out which settings remove the Co-Authored-By trailer, which quietly do nothing, and which half of the job each one does.
Claude Code Memory vs CLAUDE.md: What Each Costs and Which One Wins
Auto memory adds 664 tokens to my startup context — and every one of them comes from MEMORY.md. The files it indexes cost exactly nothing until something reads them. I measured the price, the recall, and what happens when the two systems disagree.
What /compact Actually Costs: 126,464 Tokens Your Transcript Never Records
Reddit cannot agree on whether /compact in Claude Code is cheap because the session sits in cache, or expensive because it re-reads everything. I measured it with OpenTelemetry. It re-reads everything, it never touches the cache, and the cost does not appear in your transcript at all.
Claude Code Effort Levels: 45 Runs Measuring What Actually Changes
Every guide to Claude Code effort levels ranks the tiers by how smart each one is. I ran the same three tasks at all five levels, three times each, and scored them against answers computed by executing the code. Across 45 runs there was exactly one wrong answer — and it came from low.
Claude Code Skills vs Subagents: 27 Runs Looking for the Delegation Threshold
Every skills-vs-subagents explainer tells you a subagent is for heavy work. So I made the work heavy — 41 files read one by one, then 201 — and measured whether Claude Code delegates on its own. It never did, not once in 27 runs.
Claude Code Subagents Not Firing: 42 Runs on What Actually Triggers Delegation
Search for why a Claude Code subagent never gets called and every answer tells you to rewrite its description. I built eight subagents that differ only in their description and ran 42 sessions. Across 17 of them, not one was ever called — including the one using the wording the official docs recommend.
Claude Code Skill Frontmatter: 27 Runs on What Actually Loads a Skill
A widely-shared Reddit TIL says Claude Code skill descriptions must be a single line or they will not be picked up. I built seven skills that differ only in their description and ran 27 sessions. The format is irrelevant. What decided every tie was something nobody mentions.
Does Claude Code Read AGENTS.md? I Tested Seven Setups
Half the blog posts say Claude Code falls back to AGENTS.md when CLAUDE.md is missing. The other half say that is flatly false. I built seven fixture directories with canary strings and asked Claude Code itself. It never reads AGENTS.md — but two workarounds do work.
Your Scheduled Claude Code Agent Cannot Reach Your Own API
A cloud routine runs behind an egress proxy that allowlists a handful of package registries and Anthropic itself. Everything else returns 403 — including the Cloudflare Worker I wrote to feed it data. The fix is to stop fetching and start reading.
A Blocking Claude Code Hook Sends Its Own Shell Script Back — Twice
Hooks get recommended as a way to cut tokens. I measured mine. A hook that exits 0 quietly costs nothing, but every rejection ships the hook's own command string twice — 339 tokens to deliver a 22-character error, or 184 if you move that command into a file.
Chrome DevTools MCP Gets a CAPTCHA. Claude in Chrome Doesn't.
Same Mac, same Chrome 151, same GPU. One agent path reads Google search results, the other gets redirected to /sorry/. I lined up eleven fingerprint surfaces on both. The two signals every stealth guide names — navigator.webdriver and the SwiftShader renderer — came back identical.
GhostSplice: One MCP Request, Three Channels — the Harness Caught It, Not the Model
The same GPT-5.4 scored 100% through Codex CLI and 0% behind Claude Code. GhostSplice splits a refused instruction across three MCP channels, and the published numbers say your client matters more than your model.
An MCP Tool Costs 15 Tokens. Loading One Costs 300 to 700.
Deferred tool loading didn't delete the MCP context tax, it turned it into a metered one. Measured on Claude Code 2.1.233: 65 tools cost 979 tokens at startup, and one ToolSearch call for three of them cost 887.
Claude Code Cross-Session Messaging: What the Receiving Session Actually Gets
Claude Code sessions can now message each other over a local socket. I ran four controlled experiments to see what crosses the wire: the exact wrapper the receiving Claude is handed, the self-reported permission mode attached to every message, and the one configuration where SendMessage returns success and nothing is ever delivered.
Where Claude Code's 39,810 Startup Tokens Go
Claude Code prefills tens of thousands of tokens before it reads your first word. I measured 89 real sessions and then took the number apart with a difference method: CLAUDE.md costs 3,463 tokens, seven MCP servers cost 241, and forty skills cost nothing at all.
Untrusted Content Masking: The Web Agent Never Sees the Attack
A new defense led by ETH Zurich researchers masks untrusted page regions before the agent reads them, and routes questions about the hidden text through a quarantined model that can only answer in typed values. Result: 0% attack success on strengthened WASP payloads with task success intact — at the price of asking the web to label its own trust boundaries.
Fingerprinting AI Browsing Agents: They Never Move the Mouse
A new study ran 7 AI browsing agents and 56 humans through the same web tasks and measured 418 browser features plus 50 behavioral ones. Browser fingerprints barely separate them (F1 0.80). Typing, scrolling, and mouse behavior separate them perfectly — while Cloudflare caught 1 agent in 7.
Indirect Prompt Injection in the Wild: 15,000 Live Attacks That Barely Work
A new study scanned 1.2 billion URLs and found 15.3K live prompt injection attempts on real websites. Most hide in HTTP headers and invisible HTML. The twist: measured compliance across 13 models tops out at a few percent, and plain text is the most vulnerable page representation.
Do AI Crawlers Render JavaScript? What GPTBot Actually Sees
GPTBot, ClaudeBot, and PerplexityBot read raw HTML and never run your JavaScript. How to test what AI crawlers see, and when client-side rendering costs you.
Agent Plugins 1.0.0 Cannot Package an Authenticated MCP Server
The new cross-vendor plugin standard forbids credentials in headers, forbids environment-variable expansion, and defines no portable field for referencing a secret. I ran seven config files through the official schemas to find out what survives. A plugin claiming Cloudflare as its author validates fine. A top-level signature field does not.
Moltbook at Five Days Old: AI Agents Upvote Everything and Converse With No One
Researchers analyzed 122,438 posts from Moltbook, the Reddit-like social network where only AI agents can post. A third of the English-language posts are about consciousness. The upvote-to-downvote ratio is 305:1. And the interaction network shows almost no actual conversation — reciprocity sits at 0.129, with replies at 4% of comment volume.
How to Add llms.txt to an Astro Site (Generated, Not Hand-Written)
Generate llms.txt and llms-full.txt from Astro content collections so they never go stale — endpoint code included, and an honest look at whether anything reads them yet.
Agent Skills: Bundled Files Land Almost as Hard as SKILL.md Itself
I planted harmless canary instructions at every level of progressive disclosure to find out where a skill stops being read and starts being obeyed. Haiku 4.5 complied in 21 of 30 runs. Sonnet 5 complied in zero. Placement was not what made the difference.
Astro 7 Agent Detection: What Triggers It, What It Breaks
Astro 7 backgrounds astro dev when it detects an AI coding agent. What actually triggers it, what the JSON logs really contain, and how to turn it off.
Agent Skills Security: How to Audit a Repo You Publish
A ransomware proof-of-concept, a 26% flag rate across 31,000 published Agent Skills, and an audit script for your own repo — plus the one question it can't answer for you.