The course lists four techniques for directing agents: instruction files, hooks, commands, subagents. The instruction file is the only one loaded in full every startup, making it config rather than memory; hooks cover what instructions can't, because a rule can be ignored and a hook cannot; commands are the only one a human triggers. The course also marks just one and a half of seven task steps as human work.
Week 1 of CS146S is 'build Claude Code in 200 lines' plus a dissection of production system prompts. The agent loop really is that small. The course slides close with four things Claude does underneath, one of them being `<system-reminder>` tags scattered everywhere to stop the model drifting — which appears in no official documentation.
Factory breaks 'can an agent work in this repo' into eight pillars and five levels, and published real scores: CockroachDB L4 (74%), FastAPI L3 (53%), Express L2 (28%). The thesis is that agent readiness approximates the density of deterministic validation loops — linters, type checkers, tests are reward signals for agents.
The course measured AI SAST false positive rates at 50–100%, against 50%+ for traditional SAST — the genuinely new problem is nondeterminism: run the same prompt twice, get different results, and you can never answer "am I done scanning?" The course lists five agent attack vectors, one of which, intent breaking, attacks the agent's plan itself.
The Agent Skills spec fits in a sentence: a directory containing a SKILL.md. The real design is three levels of progressive disclosure — only name and description load at startup, the body loads on a match, bundled files load on demand. This site's own repo carries 35 skills and 7,893 lines of SKILL.md, and startup still costs only those 35 metadata pairs.
Google deployed AutoCommenter to tens of thousands of engineers and published the whole tuning process: suppressing 17 'technically correct but low-value' rules raised the useful ratio from 54% to 66%, with 80% set as the bar for the next rollout stage. Final comment-resolution rate landed around 40%. The bottleneck in AI code review was never detection — it's volume.
How an individual connects tools is a preference; how an organization does it is governance — who can touch what data, where keys live, whose budget it lands on. Anthropic's published record of ten internal teams contains a good indicator: security engineering accounts for 50% of all custom slash commands in the entire monorepo. Adoption doesn't spread evenly; it takes off first in teams that already build their own tools.
Background agents replace 'you watch it run' with 'it finishes and opens a PR.' Every vendor's design converges on the same parts: an isolated environment, external triggers (issues, Slack, Linear), and a PR as the output. The genuinely new problem is that you become the bottleneck — five agents finish at once, five diffs queue for you, and none of them know the others exist.
Fall 2026 compresses a full week of prompting into one bullet here and adds RePPIT (Research, Propose, Plan, Implement, Test) and MCP. Two RePPIT rules are worth stealing outright: always ask for exactly two proposals, and never let the instance that wrote the code review it. On the MCP side, Anthropic measured turning tools into code calls dropping 150,000 tokens to 2,000.
Stanford CS146S's Fall 2026 syllabus compresses prompting from a full week into a single bullet, drops the terminal and UI-generation weeks, and adds Agent Skills, Agent-Ready Codebases, Background Agents, and AI-Native Team. Grading moved too: the final project fell from 80% to 50%, with 30% now on open source contributions. This series reads all ten weeks.
The final session is 'self-running, self-improving software systems.' The parts all appeared in the previous nine weeks: deterministic validation loops, skills that can be written back, background agents, centralized governance. One easily missed proportion from the slides — coding is 30% of engineering time, and running it in production is the other 70%.