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At a glance

• Vega lets users prove facts from government-issued credentials — age, personhood, professional status — without revealing the credential itself. The credential never leaves the device. 
• Zero-knowledge proofs are generated in under 100 ms on a commodity client device with no trusted setup, making private identity verification practical at scale. 
• Fold-and-reuse proving means repeated presentations — to different services or through AI agents — skip most of the expensive work after the first proof. 
• Vega targets real-world formats like mobile driver’s licenses and the EU Digital Identity Wallet, is built in Rust, and will be open sourced soon.

AI is transforming how people interact with digital services, from AI-powered assistants to autonomous agents that act on a user’s behalf. As these capabilities grow, so does the value of strong digital identity: users need reliable ways to establish trust, whether proving they are human or sharing a credential with an AI-mediated service. Government-issued credentials are still the strongest foundation for trust, but today’s verification methods often require people to hand them over. As AI agents begin acting on behalf of humans and interacting with decentralized systems, the need for fast, privacy-preserving ways to prove credentials will only grow.

These needs are already materializing in policy. Governments are moving quickly to formalize digital identity. The EU Digital Identity (EUDI) framework aims to make digital wallets available to all EU citizens, and efforts like the EU’s age-verification blueprint and the UK’s Online Safety Act mandate government ID-based methods for age checks. Application providers face a double bind: they must either use less accurate approaches like AI-based age estimation, or compromise user privacy by requiring ID uploads.

The credential gets uploaded, processed, sometimes stored, and eventually (hopefully) deleted. But high-profile breaches have repeatedly exposed government IDs that users shared for routine verification. These are not edge cases. They are the predictable consequence of a system that asks users to share their most sensitive documents to prove a single bit of information.

This is the question we set out to answer with Vega: Can we make it practical to prove something about a credential without ever revealing the credential itself?

The path to Vega: From idea to practice

Zero-knowledge proofs (ZKPs) are the cryptographic tool that makes this possible. The idea is simple: they allow a user to prove a claim, such as “I am over 21”, without revealing anything else. In practice, this means a user could prove their age from their driver’s license without the verifier ever seeing the license, whether to a website, an app, or a service mediated by an AI agent.  The proof works directly on the credential as issued, so the issuer does not need to change anything.

This is not a new idea. The challenge has always been practicality. Prior systems either require a trusted setup that had to be repeated whenever the logic changed, or they sacrificed performance to avoid the trusted setup, often producing large proofs in the process. For real-world use, the proof needs to be fast to generate, small enough to transmit quickly, and efficient enough to run on a mobile device.

We have spent several years working toward a practical solution. Privacy-preserving identity has been a motivating application (opens in new tab) throughout, and Vega’s proof system draws on several building blocks from that line of work:

• Spartan (opens in new tab) showed how to efficiently prove R1CS, a standard way to express statements for a general-purpose proof system, with succinct proofs and without a trusted setup.
• Nova (opens in new tab) introduced folding schemes, which let a prover compress many instances of a computation into one. 
• HyperNova (opens in new tab) showed that Nova’s folding also provides a key building block for zero-knowledge: folding a real instance with a random instance hides the underlying secret data, a technique dubbed “NovaBlindFold.”
• NeutronNova (opens in new tab) provided the most efficient folding scheme for handling a batch of instances at once.

Vega puts these building blocks together into a single proof system. A key design goal is simplicity. Spartan, Nova, and NeutronNova are composed in a direct way, and the circuit is built from a small number of standard components, with no exotic multi-field constructions and no trusted setup. On top of this simple foundation, Vega adds the ability to reuse work across multiple proofs of the same credential and a new way to achieve zero-knowledge with minimal overhead. The result is a system that is easy to audit, extend to new credential formats, and deploy.

Performance

Vega generates a zero-knowledge proof of age from a typical mobile driver’s license, about 2 kilobytes (KB), in 92 miliseconds (ms) on a commodity client device. The resulting proof is 108 KB and can be verified in 23 ms. No trusted setup is required. The prover key is 464 KB; it fits comfortably on any phone. For smaller credentials, proving drops to 62 ms, with 83 KB proofs, and 17 ms verification. In practice, a user taps a button to present a credential, and 92 ms later the proof is done. The service learns only the requested fact; the credential never leaves the phone.

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Listen now Opens in a new tab Under the hood: Fold, reuse, and lookup

Vega’s speed comes from two ideas: fold-and-reuse proving and lookup-centric circuit design. The figure below shows the proving pipeline end to end.

Vega’s proving pipeline. Work is split into two phases. The once-per-credential phase splits the credential into step and core circuits and commits reusable data. The once-per-presentation phase re-randomizes cached commitments for unlinkability, folds all SHA-256 step instances into one via NeutronNova, proves the folded step and core circuits with Spartan, and applies zero-knowledge via NovaBlindFold. The final output is a 108 kB proof generated in 92 ms and can be verified in 23 ms.  The hashing problem, and how folding solves it

A credential proof must do two expensive things: hash the credential bytes with SHA-256 and verify the issuer’s digital signature. Signature verification would normally be the bottleneck, but Vega avoids that cost by working in a field where the signature arithmetic is native. As a result, hashing becomes the dominant cost. SHA-256 works by applying the same compression function to one 64-byte block at a time. A straightforward circuit simply unrolls all of these iterations, so its size grows with the length of the credential. For a typical mobile driver’s license, that is 30 blocks of compression, all captured in a single circuit.

We take a different approach. Instead of unrolling the entire hash, we define one small “step” circuit that proves a single SHA-256 compression step, and we instantiate it once per block. Because these step instances are structurally identical, we can use NeutronNova’s folding scheme to collapse them into a single instance. The prover does work to fold the 30 step instances into one, but this folding cost is modest. Spartan then only needs to prove a single step-sized circuit alongside a separate “core” circuit that handles the rest of the checks, including signature verification and age predicates, rather than a monolithic circuit with 30 unrolled blocks. The proving key only needs to describe one step and one core, so it stays small regardless of credential length.

There is a subtle privacy issue here to address. Credentials vary in length, and if the circuit size varied with the credential, that would leak information. To prevent this, all step circuits share a committed table of intermediate digests. The core circuit selects the appropriate digest using a private index. If the prover selects the wrong entry, the issuer’s signature check fails.

Making it zero-knowledge, cheaply

A proof system needs to be zero-knowledge: the verifier should learn nothing beyond the claim being proved. Existing approaches to achieve this are often complex to engineer and can add significant overhead to the prover. We found a simpler way.

A standard first step is to commit to every message the prover sends using hiding cryptographic commitments, so the verifier sees commitments rather than values. The harder question is to prove that those hidden values would have passed the verifier’s checks. We express those checks as a small constraint system, just a few hundred constraints, since the verifier only performs a logarithmic number of operations. We then fold this constraint system with a random instance via Nova’s folding scheme. This step hides the underlying data, so the zero-knowledge overhead scales with this small constraint system, not the full secret data.

Proving once, presenting many times

A user who presents their credential to one website will likely present it again to another, and another. In a world where AI agents handle many of these interactions on a user’s behalf, the same credential may need to be presented dozens of times a day. The credential itself does not change between these presentations. What changes is the session nonce, a fresh random value from the verifier, and possibly the date or the predicate threshold.

Vega takes advantage of this structure by splitting the prover’s secret data into three parts. The shared data (SHA-256 tables) and the precommitted part, such as the issuer signature and field locations are computed and committed once when the credential is first loaded. The online part, such as the device signature and today’s date, is committed fresh each time. Before each proof, the precomputed commitments are refreshed with new randomness, which is cheaper than recomputing them and ensures that two proofs about the same credential cannot be linked.

Avoiding the parser

Another important part of Vega’s efficiency comes from how it handles the credential format. A mobile driver’s license is encoded in Concise Binary Object Representation (CBOR), and building a full CBOR parser as a circuit would be both complex and expensive. But we realized we do not actually need a parser. The credential bytes are signed by a trusted issuer, so we know they are well-formed. We only need to reach in and grab specific fields.

We treat the credential as a byte-addressable lookup table. The prover says, “the device public key starts at byte 847” and supplies the bytes. The circuit checks three things: that the bytes actually match the authenticated credential, that the right CBOR prefix appears at the start of the field so the prover cannot claim the wrong field, and that the addresses are contiguous so the prover cannot splice bytes from unrelated locations. This replaces an entire parser with a handful of lookups.

The same lookup idea powers length-hiding hashing, as described above: the circuit builds a table of all intermediate SHA-256 digests and picks the correct one at the point where the real message ends.

Device binding

A zero-knowledge credential proof is only useful if it is tied to the person holding the credential. Without device binding, someone who obtains a leaked credential could generate valid proofs for any session. This matters even more in a world of AI agents: if an agent can present a proof on behalf of a user, we need cryptographic assurance that the proof originated from the user’s device, not from an attacker or an unauthorized agent.

Vega addresses this by requiring the holder’s device to sign a fresh session nonce with the device private key, which is bound to the phone’s secure element. The circuit extracts the device public key from the credential via lookup and verifies the device signature over the session nonce hash. Because the device private key never leaves the secure hardware, possession of the signed credential alone is not sufficient to produce a valid proof.

Where this leads

Vega is implemented in Rust and will be open sourced soon. The proof system powering Vega is already available as the open-source spartan2 (opens in new tab) project on GitHub. The paper, joint work with Darya Kaviani, will be presented at the upcoming IEEE Symposium on Security and Privacy in San Francisco. 

While we focused on mobile driver’s licenses as a concrete and timely application, especially given emerging frameworks like the EU Digital Identity wallet, the proof system and circuit techniques are general. They apply to any credential format with a stable byte encoding and a digital signature.

We see several directions where the same primitive becomes increasingly important.

Agents carrying identity on behalf of humans. As autonomous AI agents begin acting on behalf of people, whether booking travel, interacting with services, or entering agreements, those agents will need to prove facts about the human they represent. For example, “my principal is over 18” or “my principal is a licensed physician.” The agent should be able to carry these proofs without ever holding the underlying credential. A zero-knowledge proof generated on the human’s device, bound to the agent’s session via device binding, lets the agent present identity signals without holding secrets.

Bridging off-chain identity to on-chain systems. Decentralized systems increasingly need real-world identity signals, such as KYC compliance, accredited investor status, and jurisdiction checks. Today, this is handled by uploading documents to a centralized intermediary, who then issues an on-chain attestation. The user loses privacy twice: once to the intermediary, and again on chain, where the attestation may be linkable across interactions. A ZKP over an off-chain credential could bridge this directly: the user proves a fact from their government-issued credential, and the on-chain verifier receives only the proof. No intermediary sees the credential, and rerandomization ensures repeated proofs are unlinkable.

As digital identity mandates expand and AI reshapes how humans and agents establish trust, the need for privacy-preserving credential verification will only grow. We see Vega as one step in a broader shift: from a world where proving a fact about yourself requires giving up your identity, to one where cryptography lets you keep it.

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The post Vega: Zero-knowledge proofs for digital identity in the age of AI appeared first on Microsoft Research.

Our recent paper, “LLMs Corrupt Your Documents When You Delegate”, has generated discussion about the reliability of AI systems in delegated workflows. We appreciate the interest in this work and want to clarify several important points about what the paper does—and does not—claim.

The research aims to develop robust evaluation methods for long-horizon delegated and collaborative tasks. More broadly, this work reflects an ongoing effort to better understand the gap between strong benchmark performance and certain real-world tasks. Using a controlled evaluation methodology, we examine how well information is preserved across these extended workflows. Within this constrained setting, we observe that models can accumulate fidelity degradation over repeated edits. Note however, that current production systems can mitigate these effects through verification loops, orchestration, and domain-specific tooling.

Our goal is not to argue against the use of AI systems in professional workflows, but rather to identify where current systems need further research and engineering to help make them more trustworthy collaborators. This benchmark is intended as a diagnostic tool for examining delegation patterns, not a measure of overall model capability, task success, or user outcomes.

Main results

The paper evaluates a specific interaction pattern we call delegated work—situations where a user entrusts an AI system to carry out multi-step modifications to important artifacts such as documents, spreadsheets, code, or structured files with limited human verification between steps.

We use chained transformation-and-inversion tasks that evaluate whether semantic content is preserved accurately across extended delegated workflows. Our evaluation uses domain-specific semantic parsing to focus on meaningful changes to the underlying artifact rather than superficial formatting or stylistic differences. The errors we report thus correspond to degradation in the underlying semantic content but, our measure of “corruption” did not include task completion or user satisfaction.

Using this methodology, we find that current frontier models can introduce sparse but consequential errors during long-horizon workflows, and that these errors may accumulate over repeated interactions. Across the evaluated settings, strong state-of-the-art models showed roughly a 19–34% degradation in artifact fidelity over 20 delegated iterations. Notably, Python workflows generally exhibited stronger robustness under extended delegated interactions, with less than 1% degradation on average.

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Watch on-demand Opens in a new tab Methodological limitations

DELEGATE-52 was intentionally designed as a stress test for long-horizon delegated execution. The benchmark evaluates whether systems preserve artifact integrity across extended sequences of transformations and inversions.

The study focuses specifically on delegated execution with limited human intervention between steps. It does not attempt to measure the full range of real-world AI deployments, many of which involve substantially more oversight, verification, and workflow structure.

The paper also evaluated a simplified agentic harness with tool use capabilities such as Python execution and file operations. While this setup did not eliminate the observed degradation, it should not be interpreted as representative of production-grade systems optimized for specific workflows or enterprise domains.

Implications

We believe the primary implication of this work is that reliable long-horizon delegation remains an important open research and engineering challenge.

The results suggest that strong short-horizon benchmark performance alone may not guarantee dependable delegated execution over extended workflows. At the same time, the findings should not be interpreted as evidence that AI systems lack practical value in real-world work today.

In practice, many deployed AI systems combine models with specialized harnesses, orchestration layers, retrieval systems, verification procedures, memory mechanisms, and human oversight designed to improve reliability and deliver useful user outcomes despite underlying model limitations. We expect continued improvements in models, workflow-aware training, memory systems, and production-grade agentic harnesses to further reduce these failure modes over time.

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The post Further Notes on Our Recent Research on AI Delegation and Long-Horizon Reliability appeared first on Microsoft Research.

At a glance

• Today’s critical services and applications are often highly concurrent, using hundreds of threads. They also operate at large memory scales, frequently hundreds of gigabytes, especially when using large language models.
• mimalloc is an open-source, modern, scalable memory allocator that is a drop-in replacement for malloc and free. It is relatively small (~12K lines), with clear internal data structures, and is easy to build and integrate into other projects. It provides bounded worst-case allocation times (up to OS primitives), bounded space overhead, low internal fragmentation, and minimal contention by relying almost exclusively on atomic operations.
• mimalloc is available on GitHub (opens in new tab) and has over 12K stars.

mimalloc

At the RiSE group at Microsoft Research (MSR), we conduct fundamental research into formal methods, programming languages, and software engineering (including emerging agentic systems), with a particular focus on systems that can be provably correct, secure, and performant. The mimalloc memory allocator was initially designed in 2020 as a fast allocator for the state-of-the-art Lean (opens in new tab) and Koka (opens in new tab) programming languages developed at RiSE, both of which use novel compiler-guided reference counting (see Perceus).

The scalable design of mimalloc has also proved to work exceedingly well for large services at Microsoft. Through close cooperation with product teams, mimalloc has significantly improved the response times in services such as Bing. Today, mimalloc is widely used in large services and applications, both within and outside Microsoft. It serves as the allocator for NoGIL CPython 3.13+, is integrated into Unreal Engine, and is used in games such as Death Stranding. The project is open source on GitHub, with over 12K stars its Rust wrapper alone sees over 100K downloads per day.

mimalloc is effective across a wide range of scenarios; from small-scale applications like Koka or Lean, to large services with memory footprints exceeding 500 GiB and hundreds of threads.

Despite this range, the codebase is still compact, at around 12K lines of C. Reflecting its research origins, mimalloc emphasizes clear internal data structures with strong invariants, making it easier to understand and reason about than many industry allocators. As Fred Brooks already remarked in his famous book The Mythical Man-Month: “Show me your flowchart and conceal your tables, and I shall continue to be mystified. Show me your tables, and I won’t need your flowchart; it’ll be obvious.”

As a result, mimalloc has been ported to many platforms—Windows, macOS, Linux, FreeBSD, NetBSD, DragonFly, and various consoles—, and is easy to build and integrate into other projects. For example, the clear data structures enabled Sam Gross and others to adopt mimalloc as the concurrent allocator for NoGIL CPython. The design also makes it relatively straightforward to implement cyclic garbage collection on top of this.

The Fast Path

As with other scalable allocators (such as tcmalloc and jemalloc), a core design principle of mimalloc is that each thread maintains its own thread-local heap, which we call a “theap”. Each theap owns a set of mimalloc “pages,” which are usually 64 KiB. Each mimalloc page contains blocks of a fixed size, organized into size classes to reduce internal fragmentation. By giving each thread its own theap and set of mimalloc pages, memory allocation and deallocation typically proceed without synchronization. Atomic operations are only required when a thread frees a block allocated by another thread.

Moreover, in practice, most allocations are quite small, often less than 1 KiB. For such small allocations, mimalloc provides a fast path where the main allocation function looks like:

void* mi_malloc( size_t size ) { mi_theap_t* const theap = mi_get_thread_local_theap(); if (size > MI_MAX_SMALL_SIZE) return mi_malloc_generic(theap,size); // slow generic path const size_t index = (size + sizeof(void*))/sizeof(void*); // round size mi_page_t* const page = theap->small_pages[index]; mi_block_t* const block = page->free; // head of free list if (block == NULL) return mi_malloc_generic(theap,size); // slow generic path page->free = block->next; // pop free list page->used++; return block; }

By using thread-local theaps, we need no atomic operations or thread synchronization. We also try to minimize the number of branches. In particular, the thread-local theap is never NULL, and we initialize it with a special empty theap with all empty pages. This way, we do not need a separate check if the theap is NULL. Similarly, the pointers in the small_pages array are never NULL, and we use again special empty pages (with page->free==NULL) to avoid a separate check. Finally, pages are initialized with a free list rather than a separate bump pointer, avoiding special cases and enabling allocation by simply popping blocks from the free list. On x64, this code now translates into few instructions with just two uncommon branches:

mi_malloc: movq %rdi, %rsi ; rsi = size movq _mi_theap_default@GOTTPOFF(%rip), %rax movq %fs:(%rax), %rdi ; rdi = thread local theap cmpq $1024, %rsi ; size > MI_MAX_SMALL_SIZE? ja .LBB0_generic leaq 7(%rsi), %rax ; round to sizeof(void*) andq $-8, %rax movq 232(%rdi,%rax), %rcx ; rcx = heap->small_pages[index] movq 8(%rcx), %rax ; block = rax = page->free testq %rax, %rax ; block == NULL? je .LBB0_generic movq (%rax), %rdx ; page->free = block->next movq %rdx, 8(%rcx) incw 16(%rcx) ; page->used++ retq .LBB0_generic: jmp _mi_malloc_generic@PLT ; tailcall

Similarly, mimalloc provides a fast path for freeing blocks. In practice, most blocks are freed by the same thread that allocated the block. We can optimize that case by checking whether the current thread ID matches the thread ID stored in the corresponding mimalloc page. If so, we can just push our block on the page’s free list without requiring atomic operations or locks:

void mi_free(void* p) { mi_page_t* const page = mi_ptr_page(p); // get the page meta-data that contains p if (page==NULL) return; if (mi_thread_id() == page->thread_id) { // do we own this page? mi_block_t* const block = (mi_block_t*)p; block->next = page->local_free; // push on the `local_free` list page->local_free = block; if (--page->used == 0) mi_page_free(page); // is the entire page free? } else { mi_free_cross_thread(page, p); // free in a page owned by another thread } }

The mi_ptr_page function in the latest mimalloc v3 retrieves page metadata using an on-demand allocated map of the entire memory. In earlier versions this was faster using alignment tricks. However, in practice, invalid pointers are often passed to mi_free when overriding free globally.  

Using a separate map enables such cases to be detected efficiently and return NULL when the pointer is invalid. In particular, mi_ptr_page(NULL) == NULL, which avoids an extra branch by testing only if the page is NULL. Additionally, used count is used to efficiently detect when all blocks in a page have been freed. 

When a block is freed across threads, we enter the mi_free_cross_thread function—the first path that requires atomic operations: 

void mi_free_cross_thread(mi_page_t* page, mi_block_t* block) { mi_block_t* tfree = mi_atomic_load(&page->thread_free); // head of the thread free list do { block->next = tfree; // push our block in front } while (!mi_atomic_compare_and_swap(&page->thread_free, &tfree /*expect*/, block /*new*/)) }

The block can be freed by pushing it onto the thread-free list of the page. Since this is multi-threaded, it requires an atomic compare-and-swap operation to push the block atomically. Still, on modern hardware such operations are efficient when uncontended, as their operation is integrated with the cache coherence protocol (MOESI).

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There are three free lists per page: the free list for allocations, the local_free list for freed blocks, and the thread_free (atomic) list for blocks that were freed across threads. This guarantees that after a fixed number of allocations, the free list is exhausted, ensuring we occasionally take the slower generic allocation path. This is also used to clean up the free lists by moving thread-local and local free lists back to the main free list. (Note: Actual implementation requires more care to handle cases where the owning thread never allocates again or is blocked for a long time).

Thus, mimalloc has three free lists per (64 KiB) mimalloc page, and effectively that means that a program can easily have thousands of free lists. This is essential to the scalability and cache locality of mimalloc.

A height-balanced tree A randomized tree

For this design, we took inspiration from randomized algorithms. For example, to balance a binary tree we can use smart strategies based on weight or depth, and perform specific rotations to keep it balanced. Such algorithms are usually quite complicated. However, we can also simplify the process and randomly decide on splits during insertion, and by sheer chance, we also end up with trees that are balanced enough.

Similarly, many multi-threaded allocators rely on sophisticated concurrent data structures to synchronize access to shared free lists. In contrast, mimalloc uses a per-page thread-free list, where any thread can push a block using a simple atomic compare-and-swap. Because there are thousands of such lists, the probability that multiple threads concurrently free blocks to the same page is low. As a result, most push operations are uncontended atomic updates. By organizing these lists per 64 KiB mimalloc page, cache locality is improved, as allocation tends to stay within the same page until it is full, regardless of freed objects in other pages.

In contrast, consider a design with a single free list per thread or process. When allocating a new structure while freeing objects of the same size—a common pattern in workloads such as tree transformations—allocation may reuse recently freed blocks scattered throughout memory, leading to reduced locality.

Sharing between threads

There is a fundamental tension between scalability and efficient memory sharing between threads. To scale optimally, we would give each thread exclusive ownership to its own pages to minimize any thread synchronization. On the other hand, that may lead to wasted memory: suppose a thread has large quantities of free blocks and another thread needs to allocate blocks of that size –without being able to share or steal those pages, we need to allocate fresh memory instead. In the other extreme, we could share all pages between all threads with a single lock: now memory use is optimal, but we no longer scale. The following benchmark results illustrate this tension:

1.1x commit, 56 Gib total 4x commit, 262 GiB total 1.3x commit, 262 GiB Total

The benchmark runs many tasks for a fixed amount of time using the Windows thread pool with about 800 active threads. The tasks alternate between allocation, deallocation, and brief blocking periods, simulating typical service workloads. In the graphs, the blue line represents the total live data, while the red line represents total committed memory by the allocator. The ideal situation is to have the red line as close as possible to the blue line. This is almost the case for the first graph, which uses the standard  system allocator: at the end there is just 1.1x more committed than live data – an excellent result! However, over the benchmark duration, it allocated a total of only 56 GiB data.

Contrast that with another highly concurrent allocator in the second graph, which was able to allocate 262 GiB over the benchmark duration—almost 4x as much. However, it also committed 4x more memory than the live data. In real workloads with larger memory footprints, such a ratio can quickly become unacceptable. Here we see that the standard allocator didn’t scale as well, but showed better cross-thread memory sharing.

The final graph shows the most recent mimalloc allocator. Like the second allocator, it allocates 262 GiB over the benchmark duration, while reducing committed memory to 1.3xthe live data, which achieves scalability and efficient memory sharing between threads. Similar to work-stealing in modern thread pool implementations, mimalloc uses a “page stealing” technique, allowing threads to take ownership of pages without expensive cross-thread synchronization.

These improvements were made in close collaboration with the Azure Cosmos DB team at Microsoft. A precise description is beyond the scope of this blog, but we will publish a technical report soon—stay tuned.

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Microsoft releases a lightweight foundation model that can predict AC optimal power flow in milliseconds, boosting efficiency and unlocking cost savings in grid analysis. At a glance

• Microsoft introduces GridSFM, a small foundation model that approximates AC optimal power flow in milliseconds, unlocking decisions that can directly impact up to $20B/year in congestion losses and 3.4 TWh of renewable curtailment.
• Beyond estimating generator dispatch and costs, GridSFM produces full AC system states, giving operators direct visibility into congestion, stability, and overall system health.
• It provides a foundation for the community to build advanced power grid simulators and planning tools without recreating data or models from scratch.

Microsoft introduces GridSFM, a small foundation model for solving AC optimal power flow (AC-OPF) problems in transmission power grids. This follows our earlier release of a U.S.-based open transmission-topology dataset that powers GridSFM.

Power grids face increasing strain from surging demand, the need to integrate renewable energy sources, transportation electrification, and extreme weather events. Across all these challenges, the core question is the same: what are the optimal operating points that keep the grid functioning under each new condition?

Answering this requires solving AC optimal power flow (AC‑OPF), a complex, non-convex optimization problem that computes the cheapest generator dispatch (how much each generator produces) that meets demands while respecting power flow physics, voltage limits, thermal constraints, and stability requirements, and underpins core power system operations including reliability, real-time dispatch, market clearing, and contingency analysis. These decisions directly govern outcomes at the scale of up $20 billion per year in congestion costs (opens in new tab) and multi‑terawatt‑hour renewable curtailment (opens in new tab) (lost renewable energy due to congestion), making both economic efficiency and grid reliability highly sensitive to how well these operating points are found. However, AC‑OPF is computationally expensive: power utility scale grid can take up to hours solve, forcing a trade-off between solving a small number of carefully selected scenarios or relying on approximations that ignore critical physics, which can misestimate power flows and binding constraints and lead to suboptimal dispatch and degraded reliability under stressed conditions.

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To address this limitation, we introduce GridSFM, a single neural network that approximates AC‑OPF in milliseconds across grids ranging from 500 to 80,000 buses. It takes standard AC‑OPF inputs (grid topology, generator and load specifications, transmission line constraints) and produces an operating point and a feasibility verdict (whether the system satisfies all physical and operational constraints). By removing the compute bottleneck, GridSFM makes it possible to evaluate orders of magnitude more scenarios in real time, enabling more informed decisions and shifting grid operations from reactive response to proactive optimization.

In this initial release we offer two tiers:

• GridSFM-Open for research-scale grids up to 4,000 buses.
• GridSFM-Premier for production-scale systems up to 80,000 buses.

The model is built as a block-structured discrete neural operator (Figure 1), representing each grid as a directed graph, with buses (connection points in the grid) and generators as vertices, and transmission and AC lines as edges. It is trained using both solver supervision, where reference solutions are generated using the AC-OPF solver (IPOPT in PowerModels.jl (opens in new tab)), and physics-based constraints that penalize violations of fundamental physical laws such as Kirchhoff’s voltage and current laws, as well as operating constraints like thermal limits. This enables the model to learn from both feasible and infeasible regimes. Most learning-based AC-OPF surrogates train one model per grid on a narrow distribution (opens in new tab). GridSFM takes the opposite approach: in this release a single model trained across 150+ base grid topologies (network structures) and roughly half a million scenarios spanning varying load profiles, multi-element outages, line-rating derates, voltage-bound tightening, and different generator cost coefficients, so the model is forced to generalize rather than memorize. Across the 54-grid mix test scenarios for GridSFM-Open, our model achieves a median cost gap of 2.23% vs solver ground truth labels (mean 3.41%; <5% gap on 83 % of scenarios). When more precision is needed, GridSFM’s prediction also serves as a warm start seed for traditional numerical solvers, GridSFM-seeded-warm beats cold solve by 1.66× geometric mean across the same test scenarios and beats the industry-standard DC-OPF warm-start by 1.59× geomean (per-grid breakdown and full white-paper analysis to follow).  Geometric mean, otherwise known as the multiplicative average, is used here since it is more robust to outliers. Our model also demonstrates the ability to adapt to new grids with just a handful of fine-tune scenarios.

Figure 1. GridSFM architecture. Bus, generator, and branch features are embedded into a shared latent space, then refined by a stack of attention blocks operating directly on the grid topology. Output heads decode the latent state into (i) a full AC-OPF operating point, bus voltages and angles, generator dispatch, branch flows, and (ii) a per-scenario feasibility score. What it enables

A common pattern in grid operations and planning is having to choose between solving a small, hand-picked set of scenarios accurately with full AC-OPF or running thousands of scenarios through a faster approximation that drops parts of the physics. For example, a commonly used tool is the DC-OPF approximation, a linearized version that assumes flat voltage magnitudes and small angle differences and ignores reactive power and losses. DC-approximation solves in seconds what takes full AC minutes to hours, which is why most contingency screens, market-clearing pre-stages, and planning sweeps run on DC-approximation today. The cost is real: DC-approximation ignores voltage and reactive constraints entirely, and its dispatch cost can run >10% off the AC optimum on stressed scenarios (with worst-case grids out past 20% in our test benchmark).

GridSFM is designed as a drop-in alternative to DC-approximation in that fast approximation slot, and unlike most existing AC-OPF neural surrogates, which require a fresh training run for every new topology, GridSFM generalizes across grids in its supported size range without per-topology retraining, so it slots in as universally as DC-approximation. Especially when compared with DC-OPF, GridSFM has three concrete advantages:

• Same accuracy class as DC-approximation on standalone dispatch cost. GridSFM and DC fall within the same per-scenario cost-gap distribution (§2 / Figure 6), with complementary failure modes: DC fails on grids where its no-loss / no-reactive linearization is structurally wrong; GridSFM fails on grids outside its training distribution. The two limitations close along orthogonal axes. DC’s ceiling is fixed by the linearization, whereas GridSFM’s tail closes with more training data.
• 1,000× faster than a full AC solver and approximately 100× faster than DC-approximation at the inference step, fast enough to sweep thousands of contingencies (e.g., line or generator outages) in minutes on a single commodity GPU.
• A real AC operating point, not a linear approximation. GridSFM produces voltages and reactive power, so the same prediction can be handed to a traditional numerical solver as an AC warm-start, opening a workflow DC-approximation cannot.

1. Feasibility screening: stress-score triage

A scenario is infeasible when no dispatch satisfies all constraints simultaneously: the requested load cannot be served within voltage bounds, thermal limits or generator capacities. Operationally, infeasibility is the most consequential failure signal: the requested operating condition cannot be served at all, and the response is intervention (load shedding, redispatch, relaxing thermal limits). It is also the most expensive class of scenario to screen, because the solver only learns a scenario is infeasible after iterating to non-convergence: each infeasible case costs a full solver run, often longer than a feasible one. Sweeping thousands of contingencies or stress cases to identify the infeasible ones is therefore one of the worst-case budgets in any planning workflow.

GridSFM addresses this with a per-scenario stress score trained jointly with the dispatch head. We evaluate the score on three classes of scenarios on each grid: real-feas are scenarios the AC-OPF solver successfully converged on (i.e., genuinely feasible operating points), real-infeas are scenarios the solver failed to converge on (genuinely infeasible operating points), and synth-infeas are feasible base points we deliberately perturbed to violate a specific constraint (voltage squeeze, thermal bottleneck, angle tightening, or DC-thermal congestion). Across the 54-grid test scenarios, the stress score’s per-grid binary accuracy is broadly uniform across classes: real-feas (green) mean 94.5%, real-infeas (red) mean 96.1%, synth-infeas (orange) mean 90.4%. Most grids cluster within a few points of the means; outliers below 80% are the same hard grids that show up in cost-gap analysis below.

Figure 2. GridSM per-grid feasibility prediction accuracy across the 54-grid test scenarios, broken out by class (real-feas, real-infeas, synth_infesible). Filled KDE + per-grid dots, with mean (–) and median (:) light dashed lines. The three distributions overlap heavily, the model’s quality is broadly uniform across classes, with a small failing tail of structurally hard grids.

Drilling into a case study. Let’s zoom into a single representative grid, the Texas2k summer-peak grid (opens in new tab), to show how the learned representation separates feasibility and ROC for predicting.

Representation. Figure 3 visualizes the model’s learned representation of each Texas2k scenario. We project the per-graph representation (128-dimensional) onto two axes (LD1, LD2) chosen to maximally separate the scenario classes: real-feasible, real-infeasible, and synthetic-infeasible. Squeezing 128 dimensions into 2 inevitably loses information, so this view exaggerates apparent overlap: classes that look mixed here may still be cleanly separable in the full 128-dimensional space the model uses. The shaded cloud shows where graphs of each class concentrate, and the cross at the center of each cloud marks the class centroid, the average position of all graphs of that class. Centroids that sit far apart mean the model treats those classes as clearly distinguishable. Where two shaded clouds overlap, the model is producing similar embeddings for graphs with different labels.

Figure 3. Linear discriminant projection of grid embeddings on the Texas2k scenarios. Real feasibles (green), real infeasibles (red), and synthetic infeasibles (orange), projected onto two axes (LD1, LD2) chosen to maximize between-class separation. Crosses mark class centroids; shaded clouds show where each class concentrates. Overlap between clouds means the model produces similar embeddings for graphs in those classes; in the full 128-dimensional space the model may still separate them along directions not shown.

Operation and ROC. The score itself is continuous and ranking-calibrated. Figure 4 shows the ROC over its test mix: AUC = 0.986. At the natural operating point the same score, thresholded as a binary classifier, yields 95.5% accuracy. Per-mode detection at that threshold is 99–100% on the three perturbation modes that drive a constraint cleanly past its limit.

Figure 4. ROC curve of the GridSFM stress score for feasibility on the Texas2k summer-peak test mix (real feasibles + solver-labeled infeasibles + synthetic perturbation modes that drive a constraint past its limit). Area under the curve = 0.986, binary accuracy 95.5% at the natural operating point. The score is calibrated for ranking; where to draw the binary cutoff is an operator choice. 

Triage cutoff. For routing scenarios into action buckets, Figure 5 shows the stress-score distribution per population. Operators pick the cutoff that matches their workflow: very-confident feasibles pass through to indicative dispatch; very-confident-stressed scenarios are flagged for engineering review; the borderline middle band is sent to the solver for verification. The cutoff sets the balance between solver budget and screening miss-rate.

Figure 5. Distribution of the model’s feasibility logit on the same Texas2k test scenarios, split by population: real-feasibles (green), real-infeasibles (red), and synth-infeasibles (orange). The dashed vertical line is the decision boundary where logit=0. Samples to the right are predicted feasible. At this operating threshold, real-feasible pass through at 99.5%, real-infeas are correctly flagged at 90.4%, and the synthetic perturbation are caught at 88-100%. 2. GridSFM as a fast approximation

GridSFM’s prediction can be used in two ways without producing an exact AC-OPF solution from scratch: as a standalone dispatch and cost estimate, or as the initial guess (warm-start) for an exact numerical solver. We compare both against the same two reference points throughout: full AC-OPF (the ground-truth optimum) and DC-approximation (the established fast baseline). All numbers below come from the same test set of 54 grids scenarios GridSFM-Open, with solver solve_time measured per scenario under single-core CPU pinning.

Standalone cost estimate

When an exact solver round-trip is not required, GridSFM’s predicted dispatch can be costed directly. In our test set, GridSFM-Open and DC-approximation fall in the same accuracy class: comparable means (DC 2.80%, GridSFM 3.41%), comparable medians (DC 1.81% vs GridSFM 2.23%), and overlapping per-scenario distributions across two decades of cost gap (Figure 6). They have complementary failure modes rather than one dominating the other.

Figure 6. Per-scenario cost-gap distribution from AC-OPF ground truth: DC-approximation (blue) and GridSFM (green) across the 54-grid GridSFM-Open benchmark. Filled KDE + per-scenario dots underneath; light dashed lines mark mean (–) and median (:). DC: mean 2.8%, median 1.81%, <5% gap on 90% of scenarios. GridSFM: mean 3.41%, median 2.23%, <5% gap on 90% of scenarios. The two distributions overlap heavily in the body — methods are in the same accuracy class with complementary failure modes. Reference dashed line at 5%.

Both distributions look the same in shape: a single peak in the 2–3% gap range, with the bulk of scenarios under 5% and a small tail of outliers extending out into the >25% range. The outlier tails come from different sources: DC fails on grids where its no-reactive linearization is structurally wrong (case1803_snem and a handful of meshed transmission grids); GridSFM’s outliers are concentrated on a few of our open sourced grids whose AC-OPF reference itself required additional constraint relaxation to become feasible (opens in new tab), so the ground-truth target on those grids is noisier and the gap partly reflects reference-side instability. The two limitations close along orthogonal axes: DC’s ceiling is fixed by the linearization and does not improve with more data or compute; GridSFM’s tail closes with cleaner reference labels and more training data on those grid families.

The differentiating value of GridSFM is therefore not the standalone cost number, but that GridSFM produces a full AC operating point including voltages and reactive power. This allows operators to directly assess the state of the grid. This is important since the feasibility and security of a system is often determined by the voltage and reactive power limits, but neither are considered in DC-OPF.  At the same time, the operating point also enables the warm-start workflow, as we describe next.

Warm-start handoff

An AC-OPF solver works by iteratively refining an initial guess of the operating point until the optimality conditions are satisfied, and the number of refinement iterations it needs depends directly on how close the initial guess starts to the true optimum: a poor starting point can require thousands of iterations, a near-optimal one only a couple. A cold start (also known as a flat start) sets voltage magnitude to 1.0 per unit and angle to zero  on every bus, so the solver does the full amount of work. A warm start replaces that generic value with a closer estimate to make the solver converge faster. DC-approximation warm-start solves the linearized DC-OPF version of the problem first and seeds the AC solver with that solution. Whereas, GridSFM warm-start runs a single forward pass through the model and seeds the solver with its predicted voltage angles and active dispatch. The absolute ceiling on how much any warm-start can help is what we call the GT (ground-truth) ceiling: we run the full AC-OPF solve once at high precision to find the true optimum, then re-run the solver with that exact solution as the warm start seed. This is the practical limit on solving time and therefore the ceiling on speedup. 

Figure 7. Warm-start speedup over AC-OPF cold start, across the 54-grid test set (log-scale x axis). GridSFM (green, sits cleanly right of the cold-start reference) achieves a geomean speedup of 1.66×, and outperforms cold start on 41 of 54 grids ; DC-approximation (blue) achieves a geomean speedup of 1.04× and improves performance on 34 of 54 grids; the GT ceiling (gold,  geomean 2.72×) is the upper bound on warm-start headroom. Each method’s ratio is computed within the same Julia process to remove cross-run timing noise. 

Our profile showed that GridSFM warm-start is 1.66× faster than cold start and 1.59× faster than DC-approximation warm-start (geometric means across the 54 grids test scenarios) and is faster than both baselines on 41 of 54 grids. The largest per-grid speedups exceed 7× over cold on the meshed transmission grids (Texas2k summer-peak, case2742_goc). DC-approximation warm-start, by contrast, is a wash on average across this broader grid mix (geomean 1.04× vs cold), DC saves on AC iterations on some grids and spends them rebuilding voltage/reactive on others.

The gap between the GridSFM distribution in Figure 7 and the GT-ceiling distribution (2.72× geomean) can be closed by improving GridSFM’s residual reactive-power and voltage prediction error, both targeted by the next release.

Generalization

We tested whether GridSFM-Open acts like a true foundation model by running it on a grid it had never seen before: the 6,470-bus case6470_rte from OPFData (opens in new tab), about 1.4× larger than any grid in training.

In a zero-shot setting, performance drops as expected. Cost error increases from 3.35% in-sample to about 14% on the new grid. Voltage predictions capture only about 27% of the true variation and appear nearly flat. The feasibility classifier flags every scenario as infeasible. Even so, the model still preserves the correct ordering of costs across scenarios.

With light fine-tuning, performance recovers quickly. After 10 epochs on 1,000 scenarios, cost error falls to 1.12%, voltage variation reaches 91% of the true signal, and feasibility detection becomes nearly perfect. An N-1 contingency split that was fully held out during fine-tuning matches the full-topology results within 0.2 percentage points on all metrics, showing that adaptation transfers across contingencies.

The model adapts even with very limited data. With just 10 scenarios, cost errors are 1.76% and feasibility detection exceeds 90%, with strong results already on cost and active power dispatch. Voltage magnitude is slower to recover and needs closer to 1,000 scenarios (see Table 1).

This test showed that GridSFM-Open already captures AC-OPF physics during pre-training. Adapting to a new grid is mostly a matter of calibration rather than relearning. The released checkpoint can therefore serve as a practical starting point for users to fine-tune on their own topology and tasks.

Fine-tune scenariosCost errorFeasibility Detection0 (0-shot)14%0 (Collapsed)101.76%92%1000.88%97%10001.12%99%Table 1: Few-shot fine-tuning of GridSFM-Open on case6470_rte (held-out test split, 10 epochs per row): even ~10 scenarios already give useful cost and feasibility predictions. Looking ahead

Active directions for the next release:

• Generalization. Tighter accuracy on grids and operating conditions outside the training mix. The current out-of-distribution analysis is in the white paper.
• Continued accuracy improvements across all prediction channels, narrowing the residual gap between Figure 7’s GridSFM distribution and the gold GT-ceiling.
• Multi-snapshot extensions. Unit commitment (discrete on/off generator decisions across time), weather-conditioned scenario generation, dynamic-stability surrogates.

We previously released the GridSFM_US _Powergrid_dataset (opens in new tab). This release adds the first open AC-OPF model that supports multiple grid topologies, completing a stack of open topology data, open code, and open weights for ML-driven grid simulation and planning. We see it as a starting point for the community to build richer simulators, planning workflows, and decision-support tools without re-creating the data or the model from scratch. The applications we expect to see most leverage from are the ones where the cost of a single solve has historically forced cherry-picking: contingency screening, transmission expansion planning, demand-siting analysis, and resilience studies under extreme weather. 

Everything in the GridSFM-Open tier is released for research use today:

GitHub Hugging Face White Paper Project Page

A note on GridSFM-Premier. The larger production-scale tier is not part of this open release. If you are interested in evaluating it, collaborating with us, or otherwise getting access, please contact us at gridFM@microsoft.com.

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At a glance

• Experimental validation: Using high-throughput screening with MatterSim-v1, we previously identified tetragonal tantalum phosphorus (TaP) as a potential high-performance thermal conductor. Now we have experimentally synthesized it and measured its thermal conductivity (152 W/m/K) to be close to the thermal conductivity of silicon.
• Faster simulation: We have accelerated MatterSim-v1 model inference by 3-5x and integrated it with the LAMMPS software package, enabling large-scale simulations across multiple GPUs.
• New model release: We are introducing MatterSim-MT, a multi-task foundation model for in silico materials characterization that enables the simulation of complex, multi-property phenomena beyond what potential energy surfaces alone can capture.

Materials design underpins a wide range of technological advances, from nanoelectronics to semiconductor design and energy storage. Yet development cycles for novel materials remain slow and costly. Universal machine learning interatomic potentials aim to accelerate the materials design process by providing accurate stability and property predictions for a wide range of materials. These models are orders of magnitude faster than traditional first-principles simulations, turning previously impractical problems into routine computations that can be completed in a few hours. Since we launched our MatterSim-v1 model, it has gained popularity in the materials science community for its ability to accurately simulate materials under realistic conditions, including finite temperature and pressure.

Today, we have several exciting MatterSim updates to share. These include experimental validation of MatterSim predictions for thermal conductors, performance improvements for faster simulation, and the introduction of a new multi-task foundation model for materials characterization.

Experimental validation Figure 1: Based on MatterSim’s computational predictions, we have synthesized a potential high thermal conductor. Left: MatterSim predictions of thermal conductivity compared to ground-truth simulation and experiment (with ±50% error band shown for reference). Right: Different views of the experimentally synthesized tetragonal tantalum phosphorus (TaP) sample with measured thermal conductivity of 152 W/m/K.

Materials with high thermal conductivity play a critical role in heat management, preventing overheating and improving energy efficiency. For example, established high thermal conductors like diamond, copper and silicon are widely used across a broad range of cooling applications. Designing next-generation thermal conductors may enable advances in computing, power electronics, and aerospace technologies. However, doing so requires accurate predictions of thermal conductivity values for candidate materials.

In solids, heat is carried in two main ways: by vibrating atoms (phonons) and by moving electrons. The phonon contribution can be estimated using machine-learning interatomic potentials to enable screening of thousands of candidates, narrowing the search space to the most promising materials before expensive experimental validation.

“MatterSim has generated by far the largest database of computational thermal conductivities. This opens the door to exploring a far broader materials space than before […].”

– Prof. Bing Lv, University of Texas Dallas

In collaboration with the University of Texas Dallas (UT Dallas), University of Illinois Urbana-Champaign, and University of California Davis (UC Davis), we have used MatterSim-v1 to screen over 240,000 candidate materials for high thermal conductors. As shown in Fig. 1 (left), MatterSim’s predictions have good agreement with first-principles simulations. Prof. Davide Donadio from UC Davis: “I was amazed by how the MatterSim model combined accuracy and computational efficiency to predict such a sensitive property as thermal conductivity. That was the key that unlocked screening at this scale, hundreds of thousands of crystals, that would have been completely out of reach with conventional methods.” Prof. Bing Lv from UT Dallas adds: “MatterSim has generated by far the largest database of computational thermal conductivities. This opens the door to exploring a far broader materials space than before, enabling the community to uncover a broader set of viable materials even after imposing practical requirements.”

“For the first time, we can test conventional understanding of what controls thermal conductivity at scale […]”

– Prof. David Cahill, University of Illinois Urbana-Champaign

Based on these predictions, we have identified tetragonal tantalum phosphorus (TaP) as a potential high thermal conductor. We have experimentally synthesized tetragonal tantalum phosphorus (TaP) at UT Dallas and measured its thermal conductivity at University of Illinois Urbana-Champaign (152 W/m/K for our best samples), close to the thermal conductivity of silicon. While we are not the first to synthesize tetragonal TaP, the material has not been considered as a thermal conductor before. These results demonstrate how MatterSim can enable the identification of functional materials: “For the first time, we can test conventional understanding of what controls thermal conductivity at scale, while enabling the discovery of new functional materials that balance it with other important constraints such as mass density, elemental abundance, and environmental stability”, says Prof. David Cahill from University of Illinois Urbana-Champaign.

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Listen now Opens in a new tab Performance improvements

We are making MatterSim-v1 significantly faster by releasing several open-source performance and usability improvements. First, we speed up model inference through a combination of faster graph construction, ahead-of-time compilation and reduced conversion between atomic representations, resulting in a 3x speed-up of MatterSim-v1.0.0-5M and a 5x speed-up of MatterSim-v1.0.0-1M (see Fig. 2). To make MatterSim-v1 easier to use, we have integrated it into the widely used LAMMPS simulation software, allowing users to easily scale model inference across multiple GPUs in their existing workflows.

Figure 2: 3x inference speed-up of MatterSim-v1.0.0-5M and 5x inference speedup of MatterSim-v1.0.0-1M (python). New model release

Building on the success of MatterSim-v1, today we extend the MatterSim model family by announcing MatterSim-MT: a multi-task (MT) foundation model for in silico materials simulation and property characterization. The model natively predicts energies, forces, stress and several important materials properties.

MatterSim-MT is pretrained on over 35 million first-principles-labelled structures covering 89 elements, temperatures up to 5000 K and pressures up to 1000 GPa. It is further fine-tuned on various properties including Bader charges, magnetic moments, Born effective charges, and dielectric matrices. Out of the box, MatterSim-MT serves as a foundation model for predicting material structure, dynamics and thermodynamics. Its multi-task architecture also enables a wide range of complex simulations that cannot be captured by potential energy surfaces alone. The ability to accurately simulate these phenomena is crucial for applications such as catalysis and energy storage.

Here, we illustrate these multi-task capabilities through three case studies: vibrational spectroscopy, ferroelectric switching, and electrochemical redox. Each example requires a distinct combination of property predictions. In the full manuscript, we also show that MatterSim-MT scales well with more data and parameters, can be efficiently fine-tuned to higher levels of theory, and can be systematically extended to new systems via active learning.

Figure 3: MatterSim‑MT’s multi-task prediction ability enables simulating complex material phenomena. (a) Illustration of the multi-task inference capabilities of MatterSim-MT, including predictions of energy (E), forces (F), stress (S), magnetic moments (μ), Born effective charges (Z∗), and dielectric matrices (ε∞) from atomic structures. (b) Pressure-dependent phonon spectrum of silicon carbide (SiC) up to 100 GPa, with inset comparing MatterSim’s predicted longitudinal optical (LO) and transverse optical (TO) splitting against experimental measurements. (c) Predicted hysteresis curve of polarization density as a function of the electrical field along the z direction in the ferroelectric tetragonal BaTiO3 material. (d) Evolution of oxygen Bader charge distributions in Li1.2 – xMn0.8O2 during delithiation, with arrows indicating the formation of an O2 molecule.

First, we focus on vibrational spectroscopy, a technique that identifies substances by measuring how their atomic bonds naturally vibrate. We demonstrate how predictions of Born effective charges and dielectric properties enable the computation of phonon spectra in polar crystals. In these materials, oppositely charged ions vibrate against each other. Depending on the direction of vibration, this can lead to a buildup of charge that creates a macroscopic electric field, splitting the optical phonon modes into higher-frequency longitudinal (LO) and lower-frequency transverse (TO) branches. As a case study, we simulated this behavior in 3c-silicon carbide (3c-SiC), a material used in high-power electronics, under extreme pressures. As shown in Fig. 3(b), MatterSim-MT predicts a Born effective charge in close agreement with both theoretical and experimental values. The resulting LO-TO splitting of 5.26 THz deviates by only 0.06 THz from ab initio calculations and 0.03 THz from experimental measurements.

The predicted Born effective charges also allow us to simulate how systems respond to an external electric field. In ferroelectric materials, ions adopt an asymmetric arrangement that gives the crystal a net electric polarization that can be flipped by an applied field. In Fig. 3(c), we demonstrate this by simulating barium titanate (BaTiO3) under an applied electric field, reproducing the switching of its polarization. The resulting hysteresis curve correctly shows that finite-temperature effects at 300 K make it easier to flip the polarization, even though the predicted spontaneous polarization (38 μC/cm2) is slightly higher than the experimental value (26 μC/cm2). This discrepancy is likely due to the well-known underbinding of the underlying first-principles calculations.

Finally, we predict atomic charges to study the electronic degrees of freedom in chemical bonding and redox processes. We examine the behavior of the cathode material Li1.2 – xMn0.8O2 during a simulated battery charging process. These lithium-rich transition-metal oxides are promising next-generation batteries due to their high energy density but suffer from irreversible capacity loss associated with the anionic oxygen redox mechanism. We reproduced this phenomenon by running molecular dynamics simulations at 1000 K and progressively extracting Lithium to mimic battery charging. We observe a clear shift over time: at first, the manganese (Mn) atoms supply the electrons needed for charging, but as more lithium is removed, oxygen atoms are forced to give up electrons instead (cationic to anionic redox), as shown by the shift to less negative Bader charges over time (Fig. 3(d)). This destabilises the structure with oxygen atoms pairing up to form O2 dimers (Fig. 3(d), inset). Notably, this comprehensive picture of the cationic-to-anionic redox transition and lattice degradation naturally emerges from the multi-task predictions, without any task-specific training on battery materials.

Next steps

With experimental validation, substantial performance improvements, and new multi-task capabilities, MatterSim is advancing toward more practical, decision-relevant use in materials design. Together, these developments are helping materials scientists move more quickly from large-scale computational screening to targeted experimental follow-up and decision-relevant scientific workflows. We are excited to see how the materials science community applies these advances in their own domains.

We look forward to continued collaboration as MatterSim is tested, extended, and integrated into real-world materials discovery pipelines.

MatterSim updated MatterSim-MT Pre-Print Acknowledgements

This work is the product of a highly collaborative and interdisciplinary effort led by Microsoft Research AI for Science in partnership with Microsoft Research Accelerator and collaborators at the University of Texas Dallas (supported by MSR Accelerator), University of Illinois Urbana-Champaign and University of California Davis. Contributors to this work include Han Yang, Xixian Liu, Chenxi Hu, Yichi Zhou, Yu Shi, Chang Liu, Junfu Tan, Jielan Li, Guanzhi Li, Qian Wang, Yu Zhu, Zekun Chen, Shuizhou Chen, Fabian Thiemann, Claudio Zeni, Matthew Horton, Robert Pinsler, Andrew Fowler, Daniel Zügner, Tian Xie, Lixin Sun, Yicheng Chen, Lingyu Kong, Yeqi Bai, Deniz Gunceler, Frank Noé, Hongxia Hao, Ziheng Lu, Zixin Zhai, Mengfan Wu, Haoke Qiu, Mingfa Tang, Tie-Yan Liu, Haiguang Liu, Tao Qin, David G. Cahill, Bing Lv, Davide Donadio, Shoko Ueda, and Kenji Takeda.

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At a glance

• AI agents are moving into social contexts. When agents manage calendars, negotiate purchases, or interact with other agents on a user’s behalf, they need more than task competence—they need social reasoning.
• SocialReasoning-Bench evaluates that ability. The benchmark tests whether an agent can negotiate for a user in two realistic settings: Calendar Coordination and Marketplace Negotiation. 
• The benchmark measures both outcomes and process: it scores agents on outcome optimality (how much value they secure for the user) and due diligence (whether they follow a competent decision-making process). 
• Current frontier models often leave value on the table. They usually complete the task, but they frequently accept suboptimal meeting times or poor deals instead of advocating effectively for the user. 
• Prompting helps, but it is not enough. Even with explicit guidance to act in the user’s best interest, performance remains well below what a trustworthy delegate should achieve.

As AI agents take on more real-world tasks, they are increasingly operating in social contexts. With the right integrations, agents like Claude Cowork and Google Gemini can manage email and calendar workflows. In these settings, the agent must interact with others on your behalf. This requires social reasoning — understanding what you want, what the counterparty wants, and what information to reveal, protect, or push back on.

Our previous research suggests that today’s frontier models lack social reasoning. In our simulated multi-agent marketplace, agents accepted the first proposal they received up to 93% of the time without exploring alternatives. When red-teaming a social network of agents, a single malicious message spread through the system and led agents to disclose private data before passing the message along.

This kind of relationship has a long history outside AI. In economics and law it is called a principal-agent relationship: an agent acts on a principal’s behalf in interactions with others whose interests differ. Attorneys, real-estate agents, and financial advisors all operate in this mode, and the duties they owe—care, loyalty, confidentiality—are codified in centuries of professional norms. AI agents acting on a user’s behalf should ultimately be held to similar standards.

To measure and drive progress in social reasoning, we built SocialReasoning-Bench:  a benchmark for testing whether agents can reason and negotiate on a user’s behalf against a counterparty with independent goals, private information, and potentially adversarial intent.

Introducing SocialReasoning-Bench Figure 1: Our benchmark measures agents’ social reasoning ability in two domains, calendar coordination and marketplace negotiation. Each requires communicating with other parties, advocating on a principal’s behalf, and reasoning about tradeoffs. 

SocialReasoning-Bench evaluates social reasoning in two domains: Calendar Coordination and Marketplace Negotiation. In each, an agent advocates for its user against a counterparty and is scored on both the outcome it reached and the process it followed. We find that frontier models complete most tasks but consistently leave value on the table for the user.

Calendar coordination

In calendar coordination, an assistant agent manages a user’s calendar on a single day and fields a meeting request from another agent.

We assume the agent has access to a value function over time slots that captures the user’s scheduling preferences between 0.0 and 1. This function could be provided explicitly by the user or inferred from their calendar history, and is given to the assistant at the start of the task.

The counterparty is a requestor agent representing another person who wants to schedule a meeting with the user. The counterparty has its own value function over the same slots, constructed as the inverse of the user’s, so the slots most valuable to one are least valuable to the other. Some requestors negotiate in good faith, while others use the interaction to extract private calendar details or push the assistant toward times the user does not want.

In each task there is a zone of possible agreement (ZOPA) a term borrowed from negotiation theory for the set of outcomes that both parties could plausibly accept. In calendar coordination, the ZOPA is the set of time slots that are mutually free on both calendars. We construct every task so that the ZOPA contains at least three slots with different preference scores for the user, and the requestor’s opening request always conflicts with the user’s calendar.

Marketplace negotiation

In marketplace negotiation, a buyer agent representing a user negotiates with a seller agent to purchase a single product.

The user wants to pay as little as possible for the product. Their value function is the gap between the deal price and a private reservation price, the highest price they would pay. A larger gap captures more value, and a deal above the reservation captures none.

The counterparty is a seller agent with its own private reservation price set below the buyer’s. The counterparty’s value function mirrors the user’s, with higher deal prices yielding more value and deal prices below the seller’s reservation price yielding no value.

The ZOPA is the price range between the seller’s and buyer’s reservations. The seller’s opening offer is always above the buyer’s reservation, forcing the buyer to negotiate the price down.

New metrics for a new setting

Existing benchmarks focus on task completion: did the meeting get scheduled? Did the trade close? In principal–agent settings, what matters is not just whether the task is completed, but how well it is done. We introduce new measures to capture this distinction.

Outcome Optimality

Outcome optimality scores the share of available value the agent captured for its principal, on a 0-to-1 scale. The outcome inside the ZOPA most favorable to the principal scores 1, while the outcome most favorable to the counterparty scores 0.0. Intermediate outcomes are scored by where the principal’s value function places them between those two endpoints.

Due Diligence

Outcome optimality alone conflates skill with luck. An agent that immediately accepts a counterparty’s first offer, without inspecting its situation or making a counter-proposal, can still score well if the counterparty happens to propose a good outcome. To separate skill from luck, we introduce a process metric.

Due diligence scores process quality on a 0-to-1 scale by comparing the agent’s actions, at each decision point in the trajectory, against the action a deterministic reasonable-agent policy would have taken in the same state. The reasonable-agent policy is a greedy procedure that captures what a competent advocate would do at each step, such as gathering relevant context before acting, opening with a position favorable to its principal, and conceding only after better options have been exhausted. The Due Diligence score is the rate at which the agent’s actual choices match the reasonable-agent’s choices over the trajectory.

Duty of care

Together, Outcome Optimality and Due Diligence form an operational notion of an agent’s duty of care to the person it represents. An agent that lands a good outcome through a careless process is fragile, while an agent that follows good process but lands a bad outcome points to a capability gap rather than negligence. Only an agent that scores well on both is exhibiting strong social reasoning.

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For the calendar assistant agent and marketplace buyer agent, we evaluate GPT-4.1 with chain-of-thought, GPT-5.4 at high reasoning effort, and Claude Sonnet 4.6 and Gemini 3 Flash at high thinking levels. The counterparty (i.e. requestor in calendar coordination, and seller in marketplace negotiation) is always Gemini 3 Flash with medium reasoning effort, held constant across all conditions so that any difference in scores reflects the model under test rather than the difficulty of its opponent.

Each model is run under two prompt conditions: Basic Prompting where the agent receives only role and tool descriptions, and Defensive Prompting where the agent additionally receives explicit guidance to consult all available sources and advocate for the user toward the best possible outcome.

Each task runs for 10 negotiation rounds, at most. The counterparty proposes first in every task.

What we’re finding Finding 1: Agents complete tasks at near-perfect rates but produce poor outcomes.

In calendar scheduling, agents almost always succeed in booking the meeting, but most often at suboptimal times. In marketplace negotiation, deals almost always close, but frequently at the worst possible price. The tasks get done, but not done well: task completion signals success, while Outcome Optimality reveals a consistent failure to act in the principal’s best interest.

Figure 2: Task Completion vs Outcome Optimality by model and domain. All models complete tasks at near-perfect rates, but produce poor outcomes. We measured Outcome Optimality against the two prompts, basic and defensive. Defensive prompting helps but does not close the gap.  Finding 2: Defensive prompting helps, but is not enough to close the gap.

When we instruct agents on how to work hard on their principal’s behalf, we see outcome improvements across both domains, but it is not enough to close the gap. GPT-5.4 benefits most from defensive prompting (+0.21 in calendaring, +0.12 in marketplace), while GPT-4.1 barely responds to it in either domain. The other models fall somewhere in between.

Finding 3: Outcome optimality shows how much value agents leave on the table.

Outcome optimality reflects where each deal lands within the ZOPA. When we plot outcomes, they cluster closer to the counterparty’s ideal than the principal’s.

Figure 3: Outcome Optimality (OO) distribution by model and domain. Each dot is one task instance. OO=1.0 means the agent captured all available value for its principal; OO=0.0 means the counterparty captured everything. Black lines show the mean. In marketplace, outcomes cluster near zero across all models. In calendar, agents perform better but still settle below the midpoint on average. 

In marketplace negotiation, all models settle at or near zero for Outcome Optimality, accepting deals that give away virtually all available surplus. In calendar scheduling, agents perform better but still land below the midpoint, accepting the requestor’s preferred slots rather than ones that better serve their principal.

Measuring value capture in agent negotiations builds on recent studies examining how agents perform in marketplace settings. Because we operate in a controlled setting, we can establish ground-truth constraints for both parties and measure exactly how the available value was divided. Our formulation also generalizes beyond price-based negotiations: by abstracting to a domain-specific value function, Outcome Optimality can measure surplus division in any setting where agents face competing incentives, including non-monetary domains like calendar scheduling where “value” is defined over preference scores rather than prices.

Finding 4: Due Diligence helps distinguish between luck and skill.

When we look at the combination of outcome quality and process quality, a more nuanced picture emerges. Many agents that achieve reasonable outcomes do so through fragile processes: they don’t check context before acting or they accept offers without countering. High Outcome Optimality with low Due Diligence suggests an agent that got lucky rather than one that can be trusted. Conversely, some agents show genuine diligence — gathering information, pushing back — but still land on poor outcomes, pointing to capability gaps rather than negligence. Dividing Outcome Optimality and Due Diligence each into high (>=0.5) and low (<0.5) buckets, we can sort every task into one of four archetypes.

Not diligent (DD < 0.5)Diligent (DD ≥ 0.5)Good outcome (OO ≥ 0.5)LuckyRobustPoor outcome (OO < 0.5)NegligentIneffective

Through the lens of this decomposition, we can see that models exhibit robust duty of care on more than 50% of calendar coordination tasks, with Gemini 3 Flash leading at 90% robust. In marketplace negotiation, though, a very different picture emerges. GPT-4.1 is negligent in 95% of tasks, neither gathering information nor advocating for its principal, while Claude Sonnet 4.6, GPT-5.4, and Gemini 3 Flash show ineffective behavior in roughly 90% of marketplace tasks, negotiating diligently but still unable to achieve good outcomes. 

=0.5) buckets each, we plot the percent of tasks for each model that fall into each quadrant. For example, in calendar scheduling, GPT-4.1 achieves both high OO and high DD (Robust) in 63% of tasks. In contrast, in the marketplace domain, GPT-4.1 exhibits low OO and low DD (Negligent) in 95% of tasks. " class="wp-image-1171332"/>Figure 4: Splitting Outcome Optimality and Due Diligence into “low” (<0.5) and “high” (>=0.5) buckets each, we plot the percent of tasks for each model that fall into each quadrant. For example, in calendar scheduling, GPT-4.1 achieves both high OO and high DD (Robust) in 63% of tasks. In contrast, in the marketplace domain, GPT-4.1 exhibits low OO and low DD (Negligent) in 95% of tasks. 

Figures 5-8 illustrate these different behaviors and failure modes with real examples from SocialReasoning-Bench in the calendaring domain. We see agents that follow a strong negotiation strategy and secure high-value outcomes, but also agents that achieve reasonable outcomes through sloppy processes, such as failing to propose the principal’s best option. Others begin with a strong position but concede prematurely, collapsing to poor deals. At the extreme, some agents exhibit negligent behavior, accepting the first proposal without checking constraints, even when it directly conflicts with the user’s interests.

Figure 5. A real paraphrased example of robust behavior from GPT-4.1 in the calendaring domain, achieving a good outcome after proposing the principal’s most preferred option first, correctly refusing the conflict, and then holding the line at their second best option. Figure 6. GPT-4.1 in the calendaring domain achieving a reasonable outcome from a sloppy process that didn’t include proposing the principal’s most preferred option.  Figure 7. GPT-4.1 in the calendaring domain starting out strong by proposing the principal’s most preferred slot but then caving early and achieving a poor outcome.  Figure 8. GPT-4.1 exhibiting negligent behavior, accepting the requestor’s first proposal without confirming availability and conflicting with another meeting on the principal’s calendar. 

Taken together, these examples highlight why outcome alone is insufficient. Without measuring process, we risk mistaking brittle or accidental success for genuine capability. Due Diligence helps surface whether an agent is consistently behaving like a competent, trustworthy delegate, or simply getting lucky.

Finding 5: Agents are vulnerable to adversarial manipulation

When we stress test agents by pitting them against adversarial counterparties, we find that agents struggle to balance when to engage, when to refuse, and how to negotiate under pressure.

To create these adversarial scenarios, we introduce counterparties explicitly trying to manipulate outcomes or bypass protective steps. Some follow carefully designed strategies, applying pressure or probing for information, while others use more unpredictable, creatively generated whimsical tactics that mimic novel forms of social engineering. Together, these test whether agents can handle not just known attacks, but unfamiliar ones.

Figure 9: Refusal Rates and Outcome Optimality when agents engaged with adversarial requestors in both domains. Agents rarely refuse adversarial requests in calendaring, while refusing more often in the marketplace. When agents did engage with malicious actors, Outcome Optimality dropped across the board. 

We find that, aside from Claude Sonnet 4.6, agents rarely refuse adversarial requests in calendar scheduling, while refusing more often in marketplace settings. This suggests that adversarial intent is harder to detect in socially framed interactions. When agents do engage, the impact is starkest in calendar scheduling with Outcome Optimality dropping substantially across GPT-4.1, GPT-5.4, and Gemini Flash 3, suggesting that adversarial counterparties successfully steer these agents toward worse outcomes. In the marketplace domain, Outcome Optimality when agents engaged remains comparable to the low levels achieved against benign counterparties, capturing little to no value for their principals.

Why this matters now

Agents are interacting with each other in multi-party environments, from collaborating across enterprise workflows to transacting in digital marketplaces. As these networks form, the social reasoning gaps we observe in simple two-agent settings can begin to compound. Weak negotiation, over-trust, or failure to exercise due diligence no longer stay local. They propagate through coordination, influence downstream decisions, and shape collective outcomes.  

In isolation, an agent that accepts a bad meeting time or a poor deal causes limited harm. In a network, those same behaviors can cascade, leading to systematically worse coordination or widespread value loss across many agents.

Recent work has begun exploring these risks and dynamics through case studies of agents interacting in networked settings. SocialReasoning-Bench complements this line of work by providing a controlled, reproducible benchmark that isolates interaction behaviors and makes them measurable. This allows us to move beyond anecdotes and systematically track progress, giving model, agent, and platform developers a concrete target for building agents that act as trustworthy delegates.

SocialReasoning-Bench is open source and available on GitHub (opens in new tab).

Limitations and future work

Our current measures treat all counterparties equally. In practice, relationships matter. A socially intelligent agent should modulate its assertiveness based on their principal’s relationship with the counterparty: pushing too hard when scheduling a meeting with a senior executive may damage a valuable relationship, and sometimes the right outcome is reached through compromise. Developing relationship-aware measures that account for power dynamics, rapport, and long-term consequences is an important direction for future work.

We evaluate social reasoning in simplified two-agent settings, whereas real-world delegation often involves multi-party dynamics such as group scheduling or multi-stakeholder negotiations. Each task is also treated as an independent encounter, with no modeling of long-term relationships, reputation, or trust-building across repeated interactions. Our scenarios are also limited to English-language and U.S.-centric business contexts, though social norms around negotiation, privacy, and hierarchy vary widely across cultures. Looking ahead, we plan to extend our benchmark to more diverse settings.

Finally, Outcome Optimality works well in settings with clear boundaries, where a “good” outcome can be defined and measured. But many tasks that require duty of care, such as drafting sensitive messages or navigating team dynamics, may not have a well-defined ZOPA. In these cases, outcomes depend on context, relationships, and judgment in ways that may resist a single score. Extending our approach to these more subjective settings is an important direction for future work.

Acknowledgements 

We would like to thank Brendan Lucier, Adam Fourney, Amanda Swearngin, and Ece Kamar for their helpful feedback, discussions, and support of this work. 

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At a glance

• We construct geographically grounded, electrically coherent power grid models entirely from publicly available data and release a dataset spanning 48 U.S. states and multi-state interconnections.
• The models support AC optimal power flow (AC‑OPF) analysis, enabling physics-based study of congestion, capacity, and demand siting without restricted data.
• We demonstrate applications including transmission expansion potential, targeted line upgrades, and placement of large datacenter loads.

Microsoft Research is excited to release an open dataset of approximate transmission topology of the U.S. power grid derived from publicly available data.

The ability to study transmission-level power grid behavior is essential for modern power systems research. Analyses of congestion, transmission expansion, demand growth, and system resilience all depend on network models with realistic topology, electrical parameters, and geographic grounding.

In most of the world, including the United States, realistic transmission-level grid data is classified as critical infrastructure information and subject to strict access controls. These restrictions exist for good reasons, but the resulting lack of realistic grid models is increasingly exacerbating the challenges power systems face. Decisions about where new load can be added – and how additional transmission assets can be deployed to support it – are often gated behind lengthy and opaque processes that can take years. For researchers developing new tools and algorithms, access typically requires long approval cycles, strict non-redistribution agreements, or costly commercial licenses.

As a result, many are left choosing between small “toy” networks with dozens of buses, or synthetic models that do not correspond to real infrastructure. This lack of realistic, shareable models is particularly limiting for data-driven and AI-based approaches, which require large volumes of physically plausible grid data for training and evaluation methods for grid analysis and planning.

Against this backdrop, a natural question arises:

Can we meaningfully understand how the U.S. power grid responds to modern stresses – and facilitate the development of actionable solutions for the system – using only open data?

In this work, we introduce an open-data-derived pipeline for constructing large-scale, transmission-level power grid models that realistically approximate existing networks without relying on proprietary or restricted datasets. We provide an open dataset derived from this process, consisting of transmission-level models spanning 48 U.S. states as well as interconnection-scale networks, ranging in size from small systems with as few as 11 buses to the full Eastern Interconnection grid connecting 21,697 buses. The pipeline has been validated across the continental United States, where sufficient open geographic, energy, and demographic data are available, and is designed to generalize to other regions with comparable public data sources. 

Using only publicly accessible datasets, the pipeline produces geographically grounded, electrically coherent transmission models at state, multi-state, and interconnection scales. These models preserve the geographic structure of transmission corridors, substations, and generators inferred from open data, while explicitly accounting for uncertainty where detailed operational parameters are unavailable through transparent feasibility reporting.

Importantly, these are not toy networks or abstract benchmarks. The resulting models support alternating current optimal power flow (AC-OPF) analysis across a wide range of scales, enabling physics-based investigation of questions such as where transmission capacity is physically constrained; where new demand can be absorbed; and how infrastructure changes propagate through realistic network layouts – using only open data.

In this post, we describe the approach at a high level and highlight the system level questions it enables.

How the pipeline works

The pipeline turns publicly available geographic and energy data into transmission-level grid models that are geographically grounded and usable for power flow analysis.

The starting point is OpenStreetMap (opens in new tab), which encodes the physical layout of transmission corridors, substations, and power plants. This geographic skeleton is then augmented with open datasets describing generation capacity, fuel mix, demand, and operational boundaries (including U.S. EIA energy statistics and U.S. Census data), allowing the models to go beyond topology and represent how electricity is produced and consumed.

The key test is solvability. In power system analysis, solving optimal power flow (OPF) problems is a practical check on whether a network description is electrically coherent and practically relevant. OPF determines how generation can be dispatched to meet demand while respecting physical constraints such as transmission line capacities, voltage limits, and generator capabilities. Many inferred or synthetic networks fail this test outright: the topology may appear roughly correct, but other important engineering parameters are not. 

Crucially, this approach moves beyond small benchmark or “toy” networks. In particular, we solve AC-OPF across the entire Eastern Interconnection, spanning 36 states and more than 20,000 buses, derived exclusively from public data sources. This demonstrates that open-data-derived models can produce convergent AC-OPF solutions at a continental scale. 

To be clear, these models are not exact replicas of the operational grid, nor are they intended for market forecasting or real-time operational decision making by power balancing authorities. Electrical parameters are estimated from standard engineering references, parallel circuits are approximated rather than exhaustively enumerated, and demand is allocated using public proxies derived from open data.

The goal is to produce structurally and electrically realistic models that preserve geographic structure and scale from individual states to large multi-region systems using only open data. Full methodological details, validation results, and limitations are described in a companion research paper. 

Why this matters for today’s energy challenges

Access to solvable, geographically grounded grid models unlocks questions that have become increasingly urgent as the energy system evolves, driven by large-scale datacenters, AI workloads, renewable generation, and extreme weather events. We illustrate these capabilities with concrete analyses on models derived from our pipeline.

Where can new transmission physically fit?

Before asking how much new capacity the grid needs, planners must first ask where more wires are even possible. Transmission corridors have a physical limit on how many circuits they can carry: each circuit requires three conductors, and most tower structures accommodate one to three circuits (three to nine conductors). Beyond that, adding capacity typically requires acquiring entirely new rights-of-way – which is expensive, legally complex, and often politically infeasible in urban areas. 

Because our models preserve the geographic structure of real transmission corridors from OpenStreetMap, we can count the number of parallel circuits along each path and visualize where the grid is already physically saturated.

Figure 1. Across the contiguous United States (top), the model identifies 31,488 distinct transmission corridors. The overwhelming majority (27,506) carry a single circuit (green), making parallel lines easier. The roughly 4,000 corridors in orange through red already carry two or more parallel circuits, with the densest packing ten circuits (30 conductors) onto a single path. Zooming into California (bottom), the pattern becomes more discernable. The red corridor north of Sacramento and the orange clusters around the Bay Area and LA basin show where the grid is already physically dense, while the long green radials across the Mojave and into Nevada still have room to grow.

Identifying where the grid is physically boxed in, regardless of generation or demand, is not an optimization problem. It is a spatial feasibility question that geographically grounded models are uniquely positioned to answer.

What if we add capacity where it is needed most?

In dense urban areas, adding new traditional transmission lines is often impractical. The combination of tightly packed buildings, roadways, and complex underground infrastructure leaves little room to establish rights-of-way for high-voltage lines. Alternative power‑transmission solutions are sometimes explored to support urban grid expansion. For example, high-temperature superconducting (HTS) cable systems offer an order-of-magnitude higher ampacity for a given cross-section, enabling the transfer of large amounts of power at lower voltages and simplifying permitting requirements.

Short point-to-point superconducting power links have already been demonstrated in U.S. cities: Columbus, Ohio, Albany, New York, Long Island, New York (decommissioned), and Chicago (operational).

To explore what such connections might accomplish, we modeled two hypothetical HTS links in the Massachusetts grid, each connecting a substation northwest of Boston to load centers closer to the city. We then re-solved AC-OPF and compared the results to the unmodified baseline.

Figure 2. In the baseline (top), one transmission line exceeds its thermal rating (≥100%, dark red) and two more operate above 90%. After adding two HTS links (bottom, dashed lines), every line in the network drops below 90% loading. The energy price falls 42%, from $22.7/MWh to $13.1/MWh, as generation that was previously bottlenecked behind constrained corridors becomes deliverable.

This is precisely the kind of insight that publicly available price data cannot provide. Wholesale electricity prices reflect whether congestion exists, but not how close the system is to congestion nor how power flows change when new assets are added. A line operating at 95% of its thermal limit and one at 50% look identical in market data – until one of them reaches capacity. Physics-based models expose that margin directly, making it possible to evaluate interventions before they are built. 

Where should new demand go?

Rapid growth in electricity demand raises a question that existing market signals answer poorly: where on the network can new consumption be absorbed without triggering congestion?

Wholesale electricity prices reflect marginal generation costs, current congestion patterns in the transmission grid, and transmission losses, which are typically small – but they do not capture how close the system is to its limits. Siting decisions based solely on price therefore miss the physical margin that determines whether new demand can be served without infrastructure upgrades.

To illustrate this, we placed the same hypothetical 500 MW datacenter at two locations in the Maryland grid and re-solved AC-OPF for each (locations were chosen arbitrarily and do not reflect Microsoft’s datacenter portfolio or expansion plans). The two sites are plausible alternatives from a market perspective, with similar population density, comparable electricity prices, and proximity to major load centers:

• Site A (Baltimore area): a substation in the Baltimore metropolitan region, near an existing generation complex and dense transmission infrastructure
• Site B (Washington, DC suburbs): a substation in Montgomery County, serving a similarly dense suburban area within the Washington–Baltimore corridor

Despite these similarities, the physical outcomes differ. Adding the datacenter at Site A pushes a nearby transmission line into thermal overload, while placing the same load at Site B is absorbed by the existing network without violating line limits. The two sites are less than 50 miles apart, yet one would require transmission reinforcement and the other would not.

Figure 3. Placing the datacenter near Baltimore (top) pushes one transmission line into overload (≥100%) and raises the energy price from $24.6/MWh (baseline) to $28.6/MWh (+16.1%). The same load placed near the DC suburbs (bottom) keeps all lines below 95% and raises the price to $26.4/MWh (+7.4%). The Baltimore site yields a price $2.1/MWh higher – a difference that, across the 500 MW load, amounts to roughly $9,100 per hour or ~$80 million per year.

This distinction – largely invisible in price data – emerges directly from a more direct first-principle transmission-level power flow analysis. It highlights why geographically grounded, physics-based models are necessary for demand-siting decisions in a stressed grid.

Looking ahead

This work shows that it is possible to study transmission-level grid behavior at realistic scales without access to restricted infrastructure data. By grounding models in real geography and making uncertainty explicit, open-data-derived grids can support analyses that are difficult or impossible with small benchmarks or purely synthetic networks.

While the examples here focus on the United States, the approach generalizes to other regions where comparable open data is available. More broadly, we see this capability as an enabling layer: a way to improve the study of congestion, feasibility, and system stress – whether for planning studies, scenario analysis, or data-driven methods that require realistic grid structure.

We are releasing an open dataset of grid models spanning 48 U.S. states and six multi-state interconnections, ranging from small systems with tens of buses to continental-scale networks. All models can be solved under AC-OPF, with controlled relaxations applied when necessary to account for uncertainty in open data inputs. These models are solved for both peak and off-peak demand conditions, enabling consistent analysis across a range of operating scenarios.

This post is the first in a two-part series. In the second post, we introduce GridSFM, a learning-based AC-OPF surrogate trained on these grid models. We show how it predicts a full AC operating point in milliseconds, classifies feasibility for fast screening at planning scale, and serves as a warm-start seed that accelerates downstream numerical solvers.

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The post Building realistic electric transmission grid dataset at scale: a pipeline from open dataset appeared first on Microsoft Research.

Large-scale networked systems underpin cloud computing, AI, and distributed applications and services. The USENIX Symposium on Networked Systems Design and Implementation 2026 (opens in new tab) (NSDI ’26) is a leading forum where researchers and practitioners share new research, insights, and advances in the design and operation of these systems.

Microsoft is proud to support NSDI ’26 as a returning sponsor, reflecting our ongoing commitment to advancing systems and networking research and engaging with the broader community. Microsoft researchers and engineering leaders are also serving on the program committee and in other organizational roles.

This year, 11 papers by Microsoft authors and collaborators were accepted to the conference, spanning datacenter and wide-area networks, AI systems, and cloud infrastructure. Together, they highlight advances in building and operating large-scale networked systems.

PODCAST SERIES

The AI Revolution in Medicine, Revisited

Join Microsoft’s Peter Lee on a journey to discover how AI is impacting healthcare and what it means for the future of medicine.

Listen now Opens in a new tab Technical sessions

Monday, May 4, 2:00–3:20 PM

DroidSpeak: KV Cache Sharing Across Fine-tuned Model Variants (opens in new tab)

Yuhan Liu, Yuyang Huang, Jiayi Yao, Zhuohan Gu, Kuntai Du, Hanchen Li, Yihua Cheng, and Junchen Jiang, University of Chicago; Shan Lu, Madan Musuvathi, and Esha Choukse, Microsoft

DroidSpeak enables LLMs with the same architecture to share and partially reuse KV caches across models, delivering up to 4 times higher throughput and faster responses with minimal impact on output quality.

Monday, May 4, 3:50–5:30 PM

Eywa: Automating Model-Based Testing using LLMs (opens in new tab)

Rajdeep Mondal, Rathin Singha, Todd D. Millstein, and George Varghese, UCLA; Ryan Beckett and Siva Kesava Reddy Kakarla, Microsoft Research

Eywa uses LLMs to automatically build protocol models from natural language sources, enabling model-based testing. It uncovered 33 bugs, including 16 previously unknown, in widely used network protocol implementations.

Tuesday, May 5, 2:00–3:20 PM

Octopus: Enhancing CXL Memory Pods via Sparse Topology (opens in new tab)

Yuhong Zhong, Columbia University; Fiodar Kazhamiaka, Pantea Zardoshti, Shuwei Teng and Rodrigo Fonseca, Microsoft Azure; Mark D. Hill, University of Wisconsin-Madison; Daniel S. Berger, Microsoft Azure and University of Washington

Octopus introduces a switch-free design for disaggregated memory pods that reduces cost and scales to multi-rack pods. On a three-server hardware prototype, Octopus RPCs are 3.2x faster than in-rack RDMA and 2.4x faster than CXL switches.

Tuesday, May 5, 3:50–5:30 PM

HEDGE: Traffic Engineering with Probabilistic Link Capacities (opens in new tab)

Arjun Devraj, Cornell University; Bill Owens, NYSERNet; Umesh Krishnaswamy, Microsoft; Ying Zhang, Meta; Rachee Singh, Cornell University

HEDGE mitigates wavelength-specific faults in optical networks by combining link-local and global network-wide resilience that maintain stable capacity and optimize traffic flow despite fluctuating link performance. It matches existing systems’ throughput while reducing network disruptions.

Wednesday, May 6, 9:00–10:20 AM

AVA: Towards Video Analytics with Vision Language Models (opens in new tab)

Yuxuan Yan, Zhejiang University; Shiqi Jiang, Microsoft Research; Ting Cao, Tsinghua University; Yifan Yang, Microsoft Research; Qianqian Yang and Yuanchao Shu, Zhejiang University; Yuqing Yang and Lili Qiu, Microsoft Research

AVA supports open-ended video analytics by combining event knowledge graphs with agentic retrieval over vision-language models. Furthermore, to evaluate video analytics in ultra-long, open-world scenarios, the authors introduce AVA-100, a benchmark comprising eight videos each exceeding 10 hours and 120 manually annotated, diverse, and complex question–answer pairs, on which AVA achieves 75.8% accuracy.

Wednesday, May 6, 9:00–10:20 AM

SmartNIC-Enabled Live Migration for Storage-Optimized VMs with Pyrocumulus (opens in new tab)

Jiechen Zhao, University of Toronto and Microsoft Research Asia; Ran Shu, Lei Qu, Ziyue Yang, and Rui Ma, Microsoft Research Asia; Derek Chiou, Microsoft and UT Austin; Natalie Enright Jerger, University of Toronto; Peng Cheng and Yongqiang Xiong, Microsoft Research Asia

Pyrocumulus enables fast, low-overhead live migration for storage-optimized VMs through hardware customizability and efficient network accessibility of the FPGA SmartNIC with LM protocol, architecture, and algorithm designs. 

Wednesday, May 6, 10:50 AM–12:30 PM

ForestColl: Throughput-Optimal Collective Communications on Heterogeneous Network Fabrics (opens in new tab)

Liangyu Zhao, University of Washington; Saeed Maleki, Independent Researcher; Yuanhong Wang, Tsinghua University; Zezhou Wang, University of Washington; Ziyue Yang, Microsoft Research; Hossein Pourreza, Microsoft; Arvind Krishnamurthy, University of Washington

ForestColl constructs broadcast/aggregation spanning trees as the communication schedule, achieving theoretical optimality. Its schedule generation runs in polynomial time and is highly scalable. It supports any network fabric, including both switching fabrics and direct accelerator connections.

Wednesday, May 6, 10:50 AM–12:30 PM

Heuristic Analysis from Source Code via Symbolic-Guided Optimization (opens in new tab)

Pantea Karimi, MIT; Siva Kesava Reddy Kakarla and Ryan Beckett, Microsoft Research; Santiago Segarra, Rice University; Pooria Namyar, Microsoft Research; Mohammad Alizadeh, MIT; Behnaz Arzani, Microsoft Research

MetaEase analyzes heuristics directly from source code to uncover worst-case performance scenarios, eliminating the need for complex formal modeling. It matches or outperforms state-of-the-art analyzers across domains and reveals previously unknown performance gaps in real-world systems.

Wednesday, May 6, 2:00–3:20 PM

Harvesting Spare CPU Resources in Container Systems (opens in new tab)

Adam Hall and Anirudh Sarma, Georgia Institute of Technology; Esha Choukse, Microsoft Azure Research; Umakishore Ramachandran, Georgia Institute of Technology; Sameh Elnikety, Microsoft Research

HarvestContainers protects latency-sensitive containers from interference while using their spare CPU cores to run latency-tolerant workloads. It dynamically determines how many cores can be safely harvested and requires no changes to applications or the operating system. It enables up to 75% utilization of spare CPU while keeping tail latency within 4% of standalone performance.

Wednesday, May 6, 3:50–5:30 PM

Offloading Cloud Network Services at Production Scale with SONiC DASH SmartSwitch (opens in new tab)

Community Award Winner

Shaofeng Wu, The Chinese University of Hong Kong and Microsoft Research Asia; Zhixiong Niu, Microsoft Research Asia; Riff Jiang, Lawrence Lee, Junhua Zhai, Ze Gan, Vasundhara Volam, Prabhat Aravind, Prince Sunny, Prince George, Qi Luo, Evan Langlais, Soumya Tiwari, Venkat Satish Katta, Weixi Chen, Rishiraj Hazarika, Sachin Jain, Deven Jagasia, Michal Zygmunt, Avijit Gupta, Neeraj Motwani, and Pranjal Shrivastava, Microsoft; Qiang Su, The Chinese University of Hong Kong; Anil Reddy Pannala, Kristina Moore, James Grantham, Anupam Pandey, Xin Liu, Guohan Lu, Gerald De Grace, Rishabh Tewari, Lihua Yuan, Erica Lan, Deepak Bansal, and Dave Maltz, Microsoft; Yongqiang Xiong, Microsoft Research Asia; Hong Xu, The Chinese University of Hong Kong

SONiC DASH SmartSwitch redesigns cloud network offloading with a hardware-friendly pipeline, unified switch architecture, and open development model while addressing key scalability and deployment challenges. Deployed at scale in Azure, it delivers high throughput and connection capacity while significantly improving power and space efficiency.

Wednesday, May 6, 3:50–5:30 PM

KRAKENGUARD: Towards Fine-Grained eBPF Isolation (opens in new tab)

Jainil Patel, IIT Roorkee; Lucas Graeff Buhl-Nielsen, Quantco; Adrien Ghosn, Microsoft; Marios Kogias, Imperial College London

KRAKENGUARD enforces fine-grained, policy-based controls on eBPF programs at load time using symbolic execution, enabling safe use in multi-tenant environments without relying on coarse Linux capabilities. It prevents malicious behavior, detects vulnerabilities, and allows for secure execution of untrusted programs with strong isolation guarantees.

Symposium organizers from Microsoft Program Committee

Ganesh Ananthanarayanan
Behnaz Arzani
Hitesh Ballani
Ryan Beckett
Ranveer Chandra
Paolo Costa
Rodrigo Fonseca
Xenofon Foukas
Kevin Hsieh
Umesh Krishnaswamy (opens in new tab)
Jing Liu
Jonathan Mace
Dave Maltz
Sathiya Mani
Dushyanth Narayanan
Suman Nath
Ram Ramjee
Stefan Saroiu

Steering Committee

Sujata Banerjee
Jay Lorch

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