Fathom

Product Management: Building Products With a Model Inside Them

The product function from first principles, and what changes once there is a model in the product.

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  • 6 levels
  • 34 topics
  • 82 lessons
  • ~37h 25m

Contents

  1. Foundations

    The whole product function, with no model in it.

    40 lessons · ~19h 20m

    1. The Product FunctionBefore any technique, the job itself. Six lessons on what product management actually is, why its authority is informal, how the work divides between product, engineering and design, and … 6 lessons · ~3h 5m
      1. ·Overview
      2. 01What a Product Manager DoesFoundations30 min
      3. 02The Product LoopFoundations30 min
      4. 03The ArtifactsFoundations30 min
      5. 04Influence Without AuthorityFoundations30 min
      6. 05How Product, Engineering and Design Split the WorkFoundations30 min
      7. 06What Good Looks LikeFoundations35 min
    2. Starting in ProductThe entry path. What the week actually contains, how people really get into the job, what to produce in the first three months, and which habits compound rather than merely look busy. … 2 lessons · ~50 min
      1. ·Overview
      2. 01The Job on a TuesdayFoundations25 min
      3. 02How People Actually Get InFoundations25 min
    3. Customers and UsersThe people the product is for, and the fact that they are usually more than one person with different interests. Separating the buyer from the user from the blocker is the thing almost … 2 lessons · ~1h
      1. ·Overview
      2. 01The Buyer, the User and the BlockerFoundations30 min
      3. 02Research That Changes DecisionsFoundations30 min
    4. Discovery and Problem FramingFinding something worth building, and killing the rest cheaply. The half of the job that happens before anybody writes code, and the half most teams compress into a week because it produces … 2 lessons · ~1h
      1. ·Overview
      2. 01Finding a Problem Worth SolvingFoundations30 min
      3. 02Interviews That Are Not UselessFoundations30 min
    5. Definition and DeliveryTurning a decision into something shipped. The mechanics of scope, sequence, the documents that change what gets built, and the week in which everything changes and you have to decide what … 2 lessons · ~1h
      1. ·Overview
      2. 01Writing a PRD That Gets BuiltFoundations30 min
      3. 02Scoping and the First VersionFoundations30 min
    6. Roadmapping and PrioritisationOrdering work when there is more of it than capacity, committing enough to be trusted without lying about dates, and refusing things in public without damaging the relationship. The part of … 6 lessons · ~2h 55m
      1. ·Overview
      2. 01Prioritisation That Survives ContactFoundations30 min
      3. 02Scoring Without Fooling YourselfFoundations30 min
      4. 03The Roadmap ProblemFoundations30 min
      5. 04Now, Next, Later or DatesFoundations25 min
      6. 05Capacity AllocationFoundations30 min
      7. 06Dependencies and the Critical PathFoundations30 min
    7. Product StrategyThe part of the job that decides which problems are worth having. Strategy is a choice about where to compete and how to win there, written down so other people can act on it, and it is … 2 lessons · ~55 min
      1. ·Overview
      2. 01Strategy, Vision and RoadmapFoundations25 min
      3. 02Where to Play and How to WinFoundations30 min
    8. Pricing and PackagingThe highest leverage product decision, and the one most often owned by nobody. What you charge for matters more than how much, tiers are a product design problem rather than a spreadsheet, … 2 lessons · ~1h
      1. ·Overview
      2. 01What Pricing Actually IsFoundations25 min
      3. 02The Value MetricFoundations35 min
    9. Design and User ExperienceEnough design craft to hold your side of the conversation: what designers actually do, how to give feedback that improves the work rather than redirecting it, and the handful of techniques … 2 lessons · ~50 min
      1. ·Overview
      2. 01What Designers Actually DoFoundations25 min
      3. 02Running a Design CritiqueFoundations25 min
    10. Technical FoundationsEnough of a systems mental model to know which requests are cheap, which are expensive, and why, without pretending to be an engineer. Deliberately stops at the point where understanding … 2 lessons · ~1h
      1. ·Overview
      2. 01How a Request Actually TravelsFoundations30 min
      3. 02APIs for Product ManagersFoundations30 min
    11. The Cross Functional LoopThe machine around the product team. Who you depend on and what each of them needs from you, the cadence that keeps it running, where work dies between functions, and how disagreements get … 6 lessons · ~2h 50m
      1. ·Overview
      2. 01Who You Actually Depend OnFoundations25 min
      3. 02The Operating CadenceFoundations25 min
      4. 03The Handoffs That BreakFoundations30 min
      5. 04Working With SalesFoundations30 min
      6. 05Working With SupportFoundations30 min
      7. 06Working With DataFoundations30 min
    12. How to Read a MetricRead this before any specific number. It prevents most of the errors the rest of the measurement topics would otherwise walk into: the wrong denominator, the mix shift, the average that … 6 lessons · ~2h 55m
      1. ·Overview
      2. 01What a Metric Is ForFoundations25 min
      3. 02The Denominator ProblemFoundations30 min
      4. 03Rates, Ratios and AveragesFoundations30 min
      5. 04Windows, Cohorts and SnapshotsFoundations30 min
      6. 05Simpson's Paradox and Mix ShiftFoundations30 min
      7. 06Leading, Lagging and VanityFoundations30 min
  2. Basic

    What a model is, and what it changes.

    5 lessons · ~2h 45m

    1. What a Model ChangesA model is not a feature you add. It is a component with five properties no other component in your stack has, and almost every strange thing about building AI products is a consequence of … 3 lessons · ~1h 45m
      1. ·Overview
      2. 01The Five FactsBasic35 min
      3. 02Deterministic and Probabilistic ProductsBasic35 min
      4. 04AI Product ShapesBasic35 min
    2. Model PrimitivesThe AI base: tokens, context, latency, cost, structured output and the choice between models. Enough to reason about a feature before designing it, and to tell which constraint will bind … 2 lessons · ~1h
      1. ·Overview
      2. 01Tokens and the Context WindowBasic30 min
      3. 02Cost Per RequestBasic30 min
    3. Discovery for AI ProductsFinding out whether a model can do the thing, cheaply, before committing a quarter to it. The discovery questions change when the component is probabilistic: the demand question is the same, … 0 lessons
      1. ·Overview
  3. Intermediate

    Build with a model in the product.

    0 lessons

    1. Specs for Non Deterministic SystemsHow to specify something whose output is different every time. The pixel spec and the acceptance criterion both stop working, and what replaces them is a behaviour contract, a rubric, and a … 0 lessons
      1. ·Overview
    2. Context and KnowledgeGetting the right information in front of the model at the right time, and making the answer checkable afterwards. Most quality problems that look like model problems are context problems, … 0 lessons
      1. ·Overview
    3. Agents and AutonomyProducts that take actions rather than produce answers. The design question is not how clever the loop is, it is how much it is allowed to do before a person looks, and what happens when it … 0 lessons
      1. ·Overview
    4. AI Product UXDesigning for a product that is sometimes wrong, often slow, and never quite the same twice. The interface carries more weight here than in deterministic software, because it is what … 0 lessons
      1. ·Overview
  4. Advanced

    Ship it safely, and survive the next release.

    0 lessons

    1. Evaluation and QualityThe topic the rest of this course rests on. An evaluation is to an AI product what a test suite is to ordinary software: the thing that lets you change a prompt, a model or a retrieval … 0 lessons
      1. ·Overview
    2. Trust, Safety and GuardrailsWhat happens when the product meets people who want it to misbehave, and when the content it processes contains instructions. Most of this is product work rather than security work, because … 0 lessons
      1. ·Overview
    3. AI Pricing and PackagingPricing a feature whose cost scales with use, when every pricing instinct in software was formed in a world where the marginal customer was free. The value metric question from Foundations … 0 lessons
      1. ·Overview
    4. Model Lifecycle and DriftYour product depends on something you do not control and that changes without asking. A model upgrade is a breaking change delivered by a third party, and the discipline for surviving it is … 0 lessons
      1. ·Overview
  5. Expert

    Measure it, cost it, and build the real thing.

    7 lessons · ~3h 40m

    1. Funnel, Retention and ExperimentsThe three measurement skills a product manager uses weekly: reading where people fall out, reading whether they come back, and knowing when a test result is real. Every formula here is … 0 lessons
      1. ·Overview
    2. Revenue and EfficiencyThe numbers a board asks about. Six lessons on what it costs to acquire a customer, how long that takes to repay, what the customer is worth, where the margin goes, and which efficiency … 1 lessons · ~45 min
      1. ·Overview
      2. 01CAC Payback, and LTVExpert45 min
    3. Business Fundamentals for ProductThe vocabulary a review assumes you already have. How the company makes money, what the finance team means by the words they use, why the cash position decides what you are allowed to … 6 lessons · ~2h 55m
      1. ·Overview
      2. 01How Your Company Makes MoneyExpert25 min
      3. 02Reading a Profit and LossExpert30 min
      4. 03Gross Margin and Cost of RevenueExpert30 min
      5. 04Unit Economics in PracticeExpert30 min
      6. 05Burn, Runway and What They PermitExpert30 min
      7. 06Capital EfficiencyExpert30 min
    4. AI Quality MetricsThe measurements that did not exist five years ago, and that most AI products still do not take. What a pass rate means, how to measure whether an answer is supported by its sources, why … 0 lessons
      1. ·Overview
    5. AI Cost and MarginWhat happens to software economics when serving a customer costs money. Where inference belongs in the accounts, which levers actually reduce it, and why your most engaged customers become … 0 lessons
      1. ·Overview
    6. Agent and Task MetricsMeasuring something that takes many steps on its own. Per step accuracy is what you can observe and whole task success is what users experience, and the gap between those two is … 0 lessons
      1. ·Overview
    7. Benchmarks and Their LimitsWhere quoted numbers come from, why most of them do not apply to you, and how to build the only benchmark that actually governs a decision, which is your own measurement of your own work … 0 lessons
      1. ·Overview
    8. Data Moats and Feedback LoopsWhether anything you build with somebody else's model is defensible, and what would make it so. The honest answer for most products is that the moat is not the model and not the data, which … 0 lessons
      1. ·Overview
    9. AI Product Org and ProcessHow the team is shaped once there is a model in the product, which rituals actually work, and what changes about the job at each level. Includes the single most underrated operating habit in … 0 lessons
      1. ·Overview
    10. Worked AI ProductsSix complete builds, each run end to end in the same order: situation, numbers, options, decision, how it is measured, and what would falsify it. These assume everything earlier in the … 0 lessons
      1. ·Overview
  6. Sectors

    The same job, bent by the market it runs in.

    7 lessons · ~4h 25m

    1. Product by SectorThe same job, bent by the market it runs in. Seven sectors, each a full product treatment rather than a list of industry facts: who actually buys, what the cycle does to the loop, what the … 7 lessons · ~4h 25m
      1. ·Overview
      2. 01Enterprise B2B SaaSSectors40 min
      3. 02FintechSectors40 min
      4. 03Ecommerce and D2CSectors35 min
      5. 04MarketplacesSectors40 min
      6. 05Devtools and InfrastructureSectors35 min
      7. 06Healthtech and Regulated CareSectors40 min
      8. 07Vertical SaaSSectors35 min

Build

Reference

About

Learn the product function as a mechanism rather than a vocabulary, then learn what changes once the product contains something slow, expensive, probabilistic and occasionally wrong: how to specify behaviour you cannot pin down, how to know it works, what to charge for it, what it costs to run, and how all of that bends by sector.

Most product writing teaches artifacts. You learn what a PRD is, what RICE stands for, what a roadmap should look like, and you are left holding templates with no theory of when each one is the wrong tool. Most AI product writing is worse: it teaches vocabulary for a field that changes every quarter. This course inverts both. Every lesson starts with the mechanism, shows the arithmetic where arithmetic decides the answer, and only then names the artifact or the tool.

Metrics live here too. Every number this course refers to is defined inside it, in its own topics, with the formula, the denominator people get wrong and a program that computes it. There is no separate metrics course to cross reference, because in practice the measurement and the decision are the same conversation.

It assumes you have worked near software and can read a table of numbers. It does not assume you have shipped anything, run a research study, owned a price, written a prompt, or managed a person.

The course is long on purpose. Product management touches strategy, engineering, design, data, pricing, abuse, economics and the organisation itself, and a short course on it can only be a glossary.

What the job looks like now#

flowchart LR
  M[":i-users: <b>Market</b><br/><small>problems, alternatives, triggers</small>"] --> D[":i-search: <b>Discovery</b><br/><small>what is true</small>"]
  D --> S{":i-compass: <b>Decide</b><br/><small>and refuse</small>"}
  S --> SP[":i-file-text: <b>Behaviour contract</b><br/><small>must, must never, should</small>"]
  SP --> B[":i-wrench: <b>Build</b><br/><small>prompt, context, tools</small>"]
  B --> E{":i-list-checks: <b>Evaluate</b><br/><small>against a bar set beforehand</small>"}
  E -->|"passes"| L[":i-rocket: <b>Ship</b><br/><small>canary, then all</small>"]
  E -->|"fails"| B
  L --> ME[":i-gauge: <b>Measure</b><br/><small>quality, cost, trust</small>"]
  ME --> V[(":i-coins: <b>Value captured</b><br/><small>retention, revenue, margin</small>")]
  ME -->|"every failure becomes a case"| E
  ME -->|"what we got wrong"| D
  B -.->|"no eval set"| X[":i-triangle-alert: <b>Shipping on vibes</b>"]
  class M neutral
  class D,B compute
  class S,SP,E,L queue
  class ME io
  class V memory
  class X warn

Two loops, not one. The outer loop is the product loop that has always existed. The inner loop, build to evaluate and back, is the one a model adds, and the dotted branch is what happens when a team never builds the eval set: it still ships, it just stops being able to tell whether it is getting better.

How this course works#

Every lesson follows the same shape.

  1. The idea in one minute. The argument, in a few sentences.
  2. A picture. The mechanism. Press Expand on any diagram to open it full size.
  3. How it really works. The precise version, with names and numbers.
  4. Run the numbers. Where arithmetic decides, a small Go program using only the standard library, so you can put your own inputs in.
  5. The AI layer. What a model changes about this specific piece of work, what it costs, and how it fails.
  6. Sector lens. The same mechanism in enterprise software, fintech, ecommerce, marketplaces, devtools, healthtech and vertical software.
  7. Remember this, Try it, Check yourself.

Two rules hold throughout. A metric is defined in exactly one lesson and linked everywhere else. Market shape is defined once, in Product by Sector, and every other sector mention states only the delta.

Where to start#

Four pages sit alongside the lessons, under Reference in the sidebar.

PageUse it when
RoadmapStart here. One path in order through everything that is written, in nine stages, with what to do before moving on from each
WorkflowsYou have to actually do something: run discovery, build an eval set, price a feature, investigate a number that moved. Nine procedures, each with its steps and what it produces
ReferencesA lesson raised a question this course stopped short of answering. Every link verified live rather than quoted from memory
GlossaryA term appeared and you want the definition this course uses, plus which topic treats it properly

If you read nothing else first, read the Roadmap. It lists only lessons that exist, so you can follow it top to bottom without hitting a topic that has not been written yet.

The topics#

flowchart LR
  A["The job,<br/>and what a model changes"] --> B["Discovery, specs<br/>and primitives"]
  B --> C["Context, agents<br/>and the interface"]
  C --> D["Evaluation,<br/>pricing and cost"]
  D --> E["Sector, lifecycle,<br/>org, worked calls"]
  class A neutral
  class B compute
  class C io
  class D queue
  class E memory
TopicYou will be able toLevel
the Product Function ✅Say what the job is, where the loop breaks, and how the work is actually judgedFoundations
Starting In ProductKnow what the week contains, how people get in, and what to produce in the first ninety daysFoundations
Customers and UsersSeparate buyer from user from blocker, and turn thousands of signals into a short listFoundations
Discovery and Problem FramingTell a real problem from a loud one, size it, and kill ideas before they cost anythingFoundations
Definition and DeliveryWrite a PRD that gets built, scope a first version, and get it launchedFoundations
Roadmapping and Prioritisation ✅Order the work, commit enough to be trusted, say no in public, and replan without whiplashFoundations
Product StrategyWrite a one page strategy that names the bets and the refusals, and tell a real moat from a storyFoundations
Pricing and PackagingChoose a value metric, build tiers, discover willingness to pay, and change a price safelyFoundations
Design and User ExperienceRun a critique, test with five users, and name the information architecture problemFoundations
Technical FoundationsRead a system well enough to know which requests are cheap, which are expensive, and whyFoundations
the Cross Functional Loop ✅Run the cadence, instrument the handoffs, and resolve escalations without burning relationshipsFoundations
How to Read a Metric ✅Spot a bad denominator, a mix shift and a vanity metric before acting on oneFoundations
What a Model ChangesName the five facts, pick the product shape you are building, and argue for not using a modelBasic
Model PrimitivesReason about tokens, latency, cost and structured output well enough to make the callBasic
Discovery for AI ProductsTell a demo from a product, decompose work into tasks, and size by error toleranceBasic
Specs for Non Deterministic SystemsWrite a behaviour contract and a rubric instead of a pixel specIntermediate
Context and KnowledgeDecide what goes in the window, ground an answer, and make it checkableIntermediate
Agents and AutonomyPlace a product on the autonomy spectrum and contain what it can get wrongIntermediate
AI Product UXSpend a trust budget, show uncertainty, and design for the wrong answerIntermediate
Evaluation and QualityBuild the dataset, grade it, gate a release on it, and read production tracesAdvanced
Trust Safety and GuardrailsPredict the abuse, build the guardrail stack, and run the incidentAdvanced
AI Pricing and PackagingPrice a feature whose cost scales with use, through credits, usage or outcomesAdvanced
Model Lifecycle and DriftSurvive a model upgrade, pin versions, and detect drift before users doAdvanced
Funnel Retention and ExperimentsBuild a cohort table, read whether the curve flattens, and know when a test is lyingExpert
Revenue and EfficiencyCompute payback, lifetime value and retention of revenue honestlyExpert
Business Fundamentals for Product ✅Read a profit and loss, know what burn allows you to propose, and answer what the board asksExpert
AI Quality MetricsMeasure groundedness, task success, acceptance, intervention and trustExpert
AI Cost and MarginPut inference in cost of revenue and find where the margin breaksExpert
Agent and Task MetricsMeasure steps, tool errors, autonomy and reliability as a compound numberExpert
Benchmarks and Their LimitsFind a real benchmark, adjust it for stage, and build your own baselineExpert
Data Moats and Feedback LoopsTest honestly whether your data is a moat, and build the flywheelExpert
AI Product Org and ProcessShape the team, run the review, and triage traces as a weekly habitExpert
Worked AI ProductsProduce and defend a complete build, with the numbers and the falsification testExpert
Product By Sector ✅Work in enterprise, fintech, ecommerce, marketplaces, devtools, healthtech or vertical softwareSectors

How the six levels are meant to be read#

Foundations is the entire product function with no model in it: the job, how to get into it, users, discovery, delivery, roadmapping, strategy, pricing, design and systems literacy, the functions around you, and how to read a number. Twelve topics, all of which would be true if generative models had never shipped, which is why they go first and why they stay true longest.

Basic is what a model is and what it changes: the five facts, the product shapes, the primitives, and how discovery works when the component is probabilistic.

Intermediate is building with one: specifying behaviour you cannot pin down, context and retrieval, agents and autonomy, and the interface that makes an imperfect answer usable.

Advanced is shipping it safely and keeping it working: evaluation, guardrails, pricing a feature whose cost scales with use, and surviving the next model release.

Expert is measurement, money and construction. Every number the job is judged on is defined here, next to the business vocabulary a review assumes you have and the topics that build real things end to end, because a number you cannot compute is a number you do not have.

Sectors comes last on purpose. The same job bent by the market it runs in only makes sense once the job itself is familiar.

What you need#

Go 1.22 or newer if you want to run the programs, and a terminal. Every program runs offline with no account, no key and no network.

A promise about names and numbers#

Tool names, benchmark figures and regulatory dates in this course were checked on 12 October 2026, and each lesson lists where its dated facts live. Benchmarks rot within a year and model capabilities rot faster. Mechanisms do not, and every lesson separates the two so you know which half to recheck.

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