CS146S Fall 2026: How to Watch and Follow Along Free

You can follow Stanford CS146S Fall 2026 for free starting Tuesday, September 22, but you can’t watch it: as of September 11, 2026, there are no official lecture recordings, and the “CS146S video” playlist Google keeps surfacing is a third-party recap of last year’s syllabus. That distinction matters more this year than last, because the Fall 2026 syllabus is a different course. Six of ten weeks are new topics, the grading now puts 30% on open-source contributions, and Tuesday/Thursday replaces Monday/Friday.

This page is the operational answer to the questions people keep landing here with: where the videos are (and aren’t), the exact Fall 2026 calendar, what’s free versus enrollment-only, what changed since Fall 2025, and a week-by-week plan that pairs each new theme with a tool you can run tonight. I’m deliberately not re-explaining the ten-week syllabus or the guest lineup here; that lives in my CS146S overview. And the lecture-by-lecture notes for the Fall 2025 material are in the CS146S study guide. This post is the layer on top for people who want to run the quarter in real time.

One receipt up front, because the calendar is the whole point. The official site’s Calendar tab is client-rendered and currently links to #, so I pulled the Fall 2026 schedule straight out of the site’s JavaScript bundle on September 11. Every date and speaker below comes from that data, not from a secondhand post.

What “CS146S Video” Actually Gets You

There is no official CS146S lecture video, and there never was. A student who worked through the Fall 2025 course wrote it plainly in his notes repo: “As of writing there are no video recordings of the lectures that are publicly available.” Nothing on the Fall 2026 site changes that. Course materials and submissions go through Stanford Canvas; Ed Discussion links go “to enrolled students.”

So what is the playlist that ranks for the query? It’s CS146S The Modern Software Development on a channel called AI With Ryan: nine videos, 14 to 16 minutes each, 29,044 views as of this week, last updated February 16, 2026. They’re AI-narrated summaries of the Fall 2025 slide decks. The Week 1 description even opens by calling CS146S a course on “scalable systems, real-world algorithms, and high-performance engineering,” which it is not. They’re fine as a commute-length preview of the 2025 topics. They are not lectures, and they cover a syllabus that Fall 2026 has largely replaced.

Here’s the honest inventory of everything you can actually press play on:

The practical consequence: “how can I watch it” has the same answer as “how can I follow along.” You read the deck, do the reading, run the exercise, and you do it on the week the class does, so the guest-talk chatter on X and the speakers’ own posts land while the topic is fresh. That’s the plan in the second half of this post.

The CS146S Fall 2026 Calendar

Fall 2026 runs ten weeks, Tuesday and Thursday, from September 22 to December 3, in room 420-041. Tuesdays are Eric’s lectures; Thursdays are mostly guests. Stanford’s 2026-27 academic calendar puts instruction start on September 22, the study-list deadline on October 9, Thanksgiving recess November 23-27, last day of classes December 4, and exams December 7-11. The course skips the Thanksgiving week entirely, which is why Week 10 lands on December 1.

Two logistics notes for people outside California. Lecture times aren’t published on the public site, only the days. And Pacific time flips from PDT (UTC-7) to PST (UTC-8) on November 1, 2026, so a Thursday afternoon guest talk is Friday early morning in Beijing, Singapore, or Tokyo either way, and one hour later after the switch. If you’re following from Europe, Thursday afternoon Pacific is late Thursday evening for you. Since you can’t attend anyway, what this actually affects is when the post-talk material shows up: speakers’ slides and threads tend to land within 24 hours, so a Friday-morning check on the syllabus tab and on X is the habit that pays off.

%%{init: {"theme":"dark","themeVariables":{"fontSize":"13px","fontFamily":"ui-sans-serif,system-ui","lineColor":"#60a5fa"}}}%%
gantt
    title CS146S Fall 2026 at a glance
    dateFormat YYYY-MM-DD
    axisFormat %b %d
    section Foundations
    W1 Agent internals           :w1, 2026-09-22, 5d
    W2 Context, specs, MCP       :w2, 2026-09-29, 5d
    section Setup
    W3 Skills and CLI            :w3, 2026-10-06, 5d
    W4 CLAUDE.md, hooks, subagents :w4, 2026-10-13, 5d
    W5 Agent-ready repos         :w5, 2026-10-20, 5d
    section Quality
    W6 Agentic code review       :w6, 2026-10-27, 5d
    W7 Security                  :w7, 2026-11-03, 5d
    section Scale
    W8 Background agents         :w8, 2026-11-10, 5d
    W9 AI-native team            :w9, 2026-11-17, 5d
    Thanksgiving recess          :crit, 2026-11-23, 5d
    W10 Software factory         :w10, 2026-12-01, 5d

What’s New in Fall 2026 vs Fall 2025

Fall 2025 was a lifecycle tour; Fall 2026 is an operator’s manual. The 2025 syllabus walked the SDLC (prompting, agents, IDE, terminal, testing, review, app building, ops, future). The 2026 syllabus assumes you already live inside a coding agent and asks how you configure, constrain, review, parallelize, and scale it. Here’s the diff, item by item:

The 30% for open-source contributions is the line to stare at. Fall 2025 was “build a thing”; Fall 2026 is “get a PR merged into a real project with an agent.” The site lists fifteen open-source partners (OpenHands, marimo, CrewAI, Semgrep, Milvus, Unsloth, cmux, pi.dev, Arize Phoenix, Browserbase, CopilotKit, HeyGen, Vercel, Warp, Anyscale), and it’s a safe bet that’s the contribution pool. Read it as the instructor saying out loud that agent-built code that never leaves your laptop isn’t the skill being taught anymore.

Two things haven’t caught up yet, and you should know before you start. The assignments repo sits at 3,950 stars and 949 forks, but its last push was November 10, 2025; it still has week1 through week8 for the 2025 syllabus and nothing for 2026. And the Fall 2026 syllabus entries currently have topics and speakers but no readings, no slides, and no assignment links. I’d expect those to appear week by week, the way they did in 2025. Until then, the 2025 repo is the only runnable material, and about half of it maps cleanly onto the new weeks (the table further down says which half).

Free vs Enrollment-Only

“Is CS146S free?” has a two-part answer: the materials are, the course isn’t. The Stanford bulletin lists it as 3-4 units, Letter or Credit/No Credit, with a September 27 application deadline for students who lack the formal prerequisites (CS111 and CS161 equivalents). The course FAQ says auditing is open “to Stanford students and staff.” I searched for an SCPD or Stanford Online listing and found none, so as of today there’s no route for a working engineer to enroll remotely.

If you want live instruction from Eric without a Stanford ID, the only option is his paid Maven course, AI Software Development: From First Prompt to Production Code: four weeks, 3-4 hours a week, eight live sessions. Its module list mirrors the Fall 2026 themes almost line for line (“Build and Integrate an MCP Server or Agent Skill,” “Implementing the RePPIT Dev Loop”), which tells you the new Stanford syllabus and the public course were designed together.

Two caveats I can’t resolve from outside: the most recent cohort I can see in the page data ran June 22 to July 17, 2026, with no fall cohort listed yet, and the price isn’t shown publicly without going through checkout. Treat it as the “I need feedback and a deadline” option, not the default.

The Follow-Along Plan: Each New Theme, Paired With a Tool

Every one of the five headline themes on the Fall 2026 site (MCP, agent skills, spec-driven development, loop engineering, the software factory) already has a runnable 2026 stack, and most of them have a deep-dive on this blog. That’s the pairing that makes following along without a classroom actually work: the lecture gives you the why and the vocabulary; the tool gives you the reps.

%%{init: {"theme":"dark","themeVariables":{"fontSize":"13px","fontFamily":"ui-sans-serif,system-ui","lineColor":"#60a5fa"}}}%%
flowchart LR
    subgraph THEMES["Fall 2026 themes"]
        direction TB
        T1["MCP + tool design
Wk 2"]
        T2["Agent skills + CLI
Wk 3"]
        T3["Spec-driven dev
RePPIT, Wk 2"]
        T4["Loop engineering
hooks, subagents, review
Wk 4 + 6"]
        T5["Software factory
background agents, gateways
Wk 8-10"]
    end
    subgraph TOOLS["Run it on"]
        direction TB
        K1["Claude Code + MCP SDK
2025 week2/3 assignment"]
        K2["SKILL.md in Claude Code
Codex CLI skills"]
        K3["OpenSpec + Superpowers
in Claude Code / Cursor"]
        K4["hooks.json, subagents
Semgrep, second-agent critic"]
        K5["Claude Code cloud tasks
LiteLLM gateway, GitHub Actions"]
    end
    subgraph READ["Deep-dive on this blog"]
        direction TB
        R1["Context engineering 2026"]
        R2["MCP vs Skills"]
        R3["OpenSpec vs Superpowers"]
        R4["Loop engineering"]
        R5["Study guide + overview"]
    end
    T1 ==> K1 --> R1
    T2 ==> K2 --> R2
    T3 ==> K3 --> R3
    T4 ==> K4 --> R4
    T5 ==> K5 --> R5
    classDef theme fill:#1e3a8a,stroke:#60a5fa,color:#dbeafe,stroke-width:2px
    classDef tool fill:#065f46,stroke:#34d399,color:#d1fae5,stroke-width:2px
    classDef read fill:#581c87,stroke:#c084fc,color:#ede9fe,stroke-width:2px
    class T1,T2,T3,T4,T5 theme
    class K1,K2,K3,K4,K5 tool
    class R1,R2,R3,R4,R5 read

The week-by-week version below is the thing to screenshot. “2025 material” is what’s runnable today from the public repo and slides; “Do this” is the one exercise I’d spend the week’s hours on; “Read” is the post on this blog that goes deeper than the deck will.

Notice where the 2025 material runs out: Weeks 3, 5, 8, 9, and 10 have no public assignment yet. That’s not a reason to wait. Those are exactly the weeks where the 2026 tooling is furthest ahead of any syllabus, and the exercises above are what practitioners were already doing this summer. If the course posts an official assignment for one of those weeks, do that one instead and treat mine as the warm-up.

Two things not to do. Don’t spend Week 1 re-reading the 2025 prompting deck; Fall 2026 skips prompting basics for a reason, and if you need them, the study guide’s two-week core is faster. And don’t stack the Maven cohort on top of this plan; the two overlap enough that you’d be paying for the same reps with a deadline attached.

One thing worth doing: pair CS146S with the agent courses running in parallel this fall, because they cover what CS146S deliberately skips (training and evaluating the agent itself). Stanford CS329Z: Engineering AI Agents (Diyi Yang, Sep 23 to Dec 2) has a public syllabus, though its recordings are Canvas-only. CMU’s 11-768: AI Agents (Graham Neubig and Daniel Fried) is the one that actually posts lecture video: four Fall 2026 lectures were on YouTube as of September 11, with more landing as the term runs. And Stanford CS329A: Self-Improving AI Agents has all nine lectures from its last run on Stanford Online’s YouTube channel. If you only have bandwidth for one companion, CMU’s is the closest thing to the “watchable” course people keep searching for.

What You Lose by Not Enrolling

You lose the two things a syllabus can’t ship: feedback on your final project, and being in the room for the guest Q&A. Everything else is recoverable with discipline. Here’s the honest accounting:

• Final project feedback (50% of the grade). A TA reading your project and telling you where the agent workflow was fake is the single most valuable thing enrolled students get. Substitute: post the project publicly and ask for review in the repo of the tool you used. It’s worse, but it’s not nothing.
• Guest Q&A. Eight practitioners, including the people who run Cursor’s developer relations, Anthropic’s Claude Code, Factory, Cognition, Semgrep, Cloudflare’s agent work, and Replit. You get their slides if they post them and whatever they tweet. You don’t get to ask Boris Cherny why hooks are designed the way they are.
• The 30% open-source scaffold. Enrolled students will have partner repos, presumably some mentoring, and a grade riding on a merged PR. You have the same fifteen partner repos on the public site. Pick one by Week 4, ship something by the Thanksgiving recess, and you’ve reproduced the deliverable, minus the grade.
• Cohort pressure. The FAQ budgets 10-12 hours a week. Nobody following along on their own sustains that for ten weeks; 5-6 hours is what I’ve seen people actually keep up, which is why the table above scopes each week to one exercise.

What you don’t lose is the content. Every deck the class sees will, based on the 2025 pattern, be a Google Slides link on the syllabus tab within days. The readings are public URLs. The tools are the same ones you’d install anyway. If you follow the calendar, do the exercises, and land one PR, you’ll finish the quarter with more evidence of skill than most enrolled students had in December 2025, when the deliverable was still a solo project.

Where This Page Stops

This post is the calendar and the plan. It intentionally doesn’t re-explain what each lecture teaches or grade the 2025 lectures; that’s the job of the overview and the study guide. I’ll update the calendar table if the course posts times, slides, or a Fall 2026 assignments branch, and I’ll note it at the top when I do.

Three facts I couldn’t verify and want on the record: the lecture time of day (not on the public site), the Maven course price and whether a fall cohort exists, and whether the 30% open-source contributions are restricted to the listed partner projects. If you’re enrolled and know any of these, the comments are open.

Related Reading

• Stanford CS146S: The Modern Software Developer, 2026 Guide: the full ten-week breakdown and guest lineup
• CS146S Study Guide 2026: Lecture-by-Lecture Notes and Workbook: verdicts and exercises for the Fall 2025 material
• Loop Engineering: Building the Cage Your AI Agent Runs In: the discipline behind Weeks 4, 6, and 8
• MCP vs Skills: Why CLI + Skill Wins the Agent Toolchain: the Week 3 argument, with token numbers
• OpenSpec vs Superpowers: My Spec-Driven Workflow: spec-driven development in practice for Week 2
• Context Engineering for Coding Agents 2026: what to put in CLAUDE.md and what to leave out