Blog

Posts on new AI releases and longer series on how real systems work, explained from the ideas they build on.

Series · 18 of 18 parts published

How US Healthcare Works

The US healthcare system end to end: who pays, who provides, and how a visit turns into a claim and a payment.

27 October 202611 min read
Jeva and the Decision Model: How Picking From a List Became Its Own Architecture
Jeva is an open 4-billion-parameter model that returns a choice, a probability or a score instead of text. Here is the line of classifiers it grew out of, how its decision head works, and what its results do and don't show.
27 October 20267 min read
How US Healthcare Works, Part 10: Prior Authorization
How a prior authorization request moves from provider to payer and back, the decision timelines in federal rules, what the 2024 CMS rule changes in 2026 and 2027, the electronic standards, and where reform and AI fit.
27 October 20266 min read
How US Healthcare Works, Part 11: Care Management
How payers try to keep members healthy and out of hospital: risk stratification, case and disease management, transitions after discharge, quality measures like HEDIS and Star Ratings, and the evidence on whether it saves money.
27 October 20267 min read
How US Healthcare Works, Part 12: From Visit to Claim
How a provider turns care into a claim: registration, documentation, charge capture and the chargemaster, coding, claim scrubbing, clearinghouses, acknowledgements and rejections, with one office visit followed end to end.
27 October 20267 min read
How US Healthcare Works, Part 13: Claim Adjudication
What happens inside a payer's system between receiving a claim and paying it: the adjudication pipeline step by step, coding edits, pricing, denials and their reason codes, pends, payment timing and corrected claims.
27 October 20269 min read
How US Healthcare Works, Part 14: The Claim SOP, Step by Step
The checks a claim examiner works through on a pended claim, in order, from eligibility and provider status through duplicates, authorization, coding, coordination of benefits and pricing, to a documented decision, with four worked cases and the appeal paths that follow.
27 October 20266 min read
How US Healthcare Works, Part 15: Payment Integrity
How payers find and recover wrong payments before and after they're made: improper payment rates, prepayment and post-payment review, clinical and coding validation, COB and subrogation recovery, fraud, waste and abuse, and risk adjustment audits.
27 October 20267 min read
How US Healthcare Works, Part 16: How Providers Get Paid
The payment methods behind US healthcare: Medicare's physician fee schedule and RVUs, DRGs and APCs, commercial rates as a multiple of Medicare, capitation, value-based contracts and bundles, and how CMS pays Medicare Advantage plans.
27 October 20266 min read
How US Healthcare Works, Part 17: Pharmacy and PBMs
How the drug benefit runs on its own rails: pharmacy benefit managers, formularies and tiers, real-time pharmacy claims, list prices and rebates, specialty drugs, the medical-versus-pharmacy split, and Medicare Part D's recent changes.
27 October 20268 min read
How US Healthcare Works, Part 18: The Data and Rules Underneath, and Where AI Fits
The transactions, privacy rules and interoperability standards that every part of US healthcare runs on, the data problems that cause most failures, and where AI helps, where it's risky, and what rules now govern it.
27 October 20268 min read
How US Healthcare Works, Part 3: Premiums, Cost Sharing and How a Plan Pays
Premiums, deductibles, copays, coinsurance and the out-of-pocket maximum, worked through one family's year of claims, plus networks, surprise bills and HSAs.
27 October 20268 min read
How US Healthcare Works, Part 4: The Code Systems
ICD-10 diagnoses, CPT and HCPCS procedures, modifiers, DRGs, revenue codes, NDCs and the identifiers that turn a doctor's visit into data a payer can process.
27 October 20267 min read
How US Healthcare Works, Part 5: Coverage Policy
How a plan decides whether a service is covered at all: Medicare's national and local coverage determinations, Medicare Advantage rules, commercial medical policies, and the criteria vendors behind them.
27 October 20267 min read
How US Healthcare Works, Part 6: Eligibility and Enrollment
How members get into a payer's system, how a provider checks coverage before a visit, what goes wrong with retroactive changes, and how two plans decide which pays first.
27 October 20268 min read
How US Healthcare Works, Part 7: Network Management
How payers build provider networks: contracting and rates, credentialing and primary source verification, the provider data behind directories and claims, and the rules on network adequacy.
27 October 20266 min read
How US Healthcare Works, Part 8: Benefit Digitization
How a health plan's benefits, written in documents for people, become configuration a claim system can run: service categories, cost-share rules, limits and authorization flags, and where it goes wrong.
27 October 20266 min read
How US Healthcare Works, Part 9: Utilization Management
How payers review whether care is medically necessary before, during and after it happens: prospective, concurrent and retrospective review, inpatient versus observation, who makes the decision, and where review goes wrong.
25 October 20268 min read
Kimi K3.1 and the Road From Softmax Attention to Kimi Delta Attention
Kimi K3.1 Pro is a 2.8-trillion-parameter open model in which three of every four attention layers keep a fixed-size memory instead of a growing KV cache. Here is how attention got there, step by step.
25 October 20267 min read
Right Screen, Wrong Transition: Using a World Model to Catch Hijacked GUI Agents
A login screen is safe after tapping Sign in and suspicious after tapping View order. A new paper checks each step of a phone or browser agent by predicting the next screen in embedding space, and catches hijacks a screen-only monitor provably cannot.
23 October 20265 min read
Agent Skills, Explained: What They Are and How They Differ From MCP
Agent Skills became a vendor-neutral standard on 22 October 2026. Here is what a skill is, how agents load them without filling their context, and where they fit next to MCP.
23 October 20266 min read
Do AI Agents Need a Memory System? What Two New Papers Found
MemoryTax found that a strong model searching its raw history beat memory frameworks, and TurnCost found that an agent's bill grows with its turns, not with the size of tool output.
23 October 20267 min read
How US Healthcare Works, Part 1: Members, Patients, Providers and Payers
Who the players in US healthcare are, how many of each there are, and how money and information move between them when someone sees a doctor.
23 October 202610 min read
How US Healthcare Works, Part 2: Public and Private Coverage
Medicare and its four parts, Medicaid and CHIP, employer plans, the ACA marketplaces and the military and veterans' systems: who each one covers, who pays for it, and how it reaches providers.
22 October 20268 min read
From Image Classifiers to H-JEPA: Learning by Predicting What Matters
How vision models went from needing a label on every image to world models that plan by predicting in their own representation space, and what the new H-JEPA paper adds.