Thinking at Scale
Implications for Software Design, Engineering, and Architecture
Thinking at Massive Scale: Implications for Software Design, Engineering, and Architecture
aleatoric research
aleatoric, llc
February 2026
Abstract
Software engineering's foundational principles—Brooks' Law, Conway's Law, Team Topologies, DRY, and Amdahl's Law—encode assumptions about human cognition, communication cost, and labor economics that become invalid when the implementing workforce shifts from small teams of expensive engineers to swarms of 1,000 or more AI coding agents. We argue that this shift constitutes not an acceleration of existing practice but a phase change in the nature of software production. With implementation cost approaching zero, the bottleneck migrates from code generation to specification, verification, and coordination. We formalize this migration through a delivery latency decomposition () and introduce three concepts that characterize the new regime: the Spec Throughput Ceiling (STC), the maximum rate at which an organization can produce unambiguous, machine-checkable task specifications; the Evidence-Carrying Patch (ECP), a change unit bundled with structured correctness proof; and the Agent-Parallel Fraction (APF), the proportion of a backlog executable independently under frozen contracts, which governs achievable speedup via Amdahl's Law. We propose Protocol-Imprinted Architecture (PIA) as an evolution of Conway's Law: in agent-scale development, software topology mirrors orchestration protocol topology rather than organizational communication structure. Cross-domain precedents from VLSI/EDA, genomics, MapReduce, and biological morphogenesis demonstrate that massive parallelism is achievable but demands heavy investment in specification, decomposition, verification, and aggregation infrastructure—a finding consistent across every domain that has confronted the transition from artisanal to industrial-scale production. Architecture must optimize for low dependency diameter, high contract strength, and merge commutativity rather than human comprehension. However, new constraints emerge: context window limits replace cognitive load, coordination tax scales with agent count, and correlated model failure introduces systemic risk. We conclude that the future of software engineering lies not in prompting better code but in designing systems that verify trust at scale—shifting the discipline from implementation to specification, verification, and governance.
1. Introduction: The Phase Change
1.1 From Scarcity to Abundance
For fifty years, software engineering has functioned as a rationing system. Every methodology from Waterfall to Agile to DevOps represents a strategy for prioritizing limited developer hours against effectively infinite business requirements (Brooks, 1975; Beck et al., 2001; Skelton and Pais, 2019). The Waterfall model rationed by phase: specify completely, then implement once. Agile rationed by iteration: deliver the highest-value increment each sprint. DevOps rationed by feedback: deploy continuously and let production telemetry guide the next allocation of scarce engineering attention. In each paradigm, the binding constraint was the same: software is built by humans, and humans are expensive, cognitively limited, and slow relative to the demand for software.
We are witnessing the dissolution of that constraint. The arrival of multi-agent orchestration systems capable of coordinating 1,000 or more AI coding agents working in parallel on a single codebase represents not an incremental improvement in developer tooling but a qualitative shift in the mode of software production (Cursor, 2026; Anthropic, 2025; He et al., 2025). Anthropic's multi-agent research system reported a 90% reduction in research task completion time compared to sequential execution, with token usage explaining approximately 80% of performance variance—evidence that scaling agent count yields returns fundamentally different from scaling human headcount (Anthropic, 2025). Cursor's "self-driving codebases" experiment reported over 1,000 commits per hour from a swarm of concurrent agents building a functional web browser from scratch (Cursor, 2026). These are vendor-reported results from 2025–2026 engineering blog posts (non-archival), not peer-reviewed studies; they should be understood as existence proofs that agent-scale orchestration is technically feasible, pending independent replication.
The shift from scarcity to abundance has a precise analogue in economic history. When a commodity transitions from scarce to abundant—electricity replacing gas lighting, containerized shipping replacing break-bulk cargo—the downstream effects are not merely quantitative. They are structural. The industries that consumed the newly abundant resource reorganize around different bottlenecks, different optimization targets, and different institutional arrangements (Jevons, 1865). Software engineering stands at exactly such a transition point.
1.2 A Phase Change, Not a Speedup
The distinction between acceleration and phase change is critical. Acceleration means doing the same thing faster. A phase change means the system reorganizes around a different set of constraints. We argue for the latter.
In the human-scarcity regime, the dominant cost in delivering software was implementation: translating a known requirement into working code. Architecture, process, and tooling were designed to maximize the productivity of this expensive step. Code review existed because human code is error-prone. DRY existed because human maintenance is costly. Microservices existed because human teams need autonomy (Hunt and Thomas, 1999; Lewis and Fowler, 2014). Every practice was an adaptation to the same underlying scarcity.
In the agent-abundance regime, implementation approaches commodity pricing. Anthropic reports that multi-agent systems consume approximately 15x more tokens than single-agent interactions, but the marginal cost per resolved issue continues to fall as models improve and inference costs decline (Anthropic, 2025). The 2025 DORA Report confirms that AI adoption correlates with increased deployment frequency but notes that stability degrades in organizations lacking robust platform engineering (Google Cloud, 2025). This finding—that speed without institutional adaptation produces fragility—is the empirical signature of a phase change, not a speedup.
The benchmark evidence supports this reading. SWE-bench, the standard evaluation for coding agents, saw resolution rates rise from under 2% to above 60% on the Verified subset between 2024 and late 2025 (Jimenez et al., 2024; OpenAI, 2025). Yet when SWE-EVO extended the benchmark to multi-issue long-horizon software evolution—requiring agents to interpret release notes and modify an average of 21 files per task—resolution rates dropped to 21%, compared to 65% on single-issue fixes (SWE-EVO, 2025). The bottleneck is not generation capacity but the ability to maintain coherent intent across extended sequences of changes: a specification and coordination problem, not an implementation problem.
We formalize the delivery latency of a software change as:
where is the time to produce an unambiguous specification, is the delay imposed by dependency resolution and coordination, is the time to establish correctness, is the merge and deployment latency, and is the raw implementation time (assuming sequential, non-overlapping stages; in practice, stages may overlap, in which case approximates the critical-path latency). In the human regime, dominates: weeks of engineering effort dwarf the hours spent on specification and verification. In the agent regime, compresses toward minutes or seconds, and the remaining terms—, , —become the binding constraints. This is the Spec Throughput Ceiling (STC) in action: the rate of correct software production is bounded not by coding speed but by the rate at which organizations can produce machine-checkable specifications (see Section 4 for a full treatment).
Figure 1. The delivery latency stack. In the human regime (left), constitutes the majority of total delivery latency, with specification, dependency resolution, verification, and integration as comparatively minor overheads. In the agent regime (right), compresses to near zero, revealing and as the dominant terms. The total latency may decrease, but the composition of that latency changes fundamentally, demanding different optimization strategies.
1.3 The Methodology Timeline
The progression of software engineering methodologies traces a consistent pattern: each era identified a different bottleneck and organized practice around relieving it. Table 1 summarizes this progression.
Table 1. Methodology timeline and bottleneck shifts.
| Era | Methodology | Primary Bottleneck | Optimization Strategy |
|---|---|---|---|
| 1960s–1970s | Waterfall | Requirements ambiguity | Specify completely before implementing |
| 1980s–1990s | Structured methods, CASE | Complexity management | Abstraction, modular decomposition |
| 2000s | Agile, XP | Feedback latency | Short iterations, continuous integration |
| 2010s | DevOps, SRE | Deployment friction | Automation, infrastructure as code |
| 2020s | AI-assisted (Copilot era) | Implementation throughput | Code generation, autocomplete |
| 2025+ | Agent-scale orchestration | Specification + Verification | Parallel execution, formal contracts, evidence-carrying patches |
Each row represents a genuine advance, but each also assumes a particular scarcity regime. The agent-scale row is qualitatively different: for the first time, the bottleneck is not a shortage of implementation capacity but a shortage of trustworthy specification and verification capacity. The implication is that a research agenda emphasizing only speed and productivity will read as hype; one emphasizing institutional redesign for verification, accountability, and governance under agent abundance will be both novel and durable.
1.4 The Central Framing: Code Abundance Versus Trust Scarcity
The appropriate framing for this transition is not "faster development" but code abundance versus trust scarcity. When 1,000 agents can generate 1,000 candidate implementations of a specification in parallel, the scarce resource is not code but confidence that the code is correct, secure, and aligned with intent.
This framing draws on evidence from multiple sources. The Stack Overflow 2025 Developer Survey reports that while 84% of developers use AI tools, only 29–33% trust the accuracy of AI outputs, with 66% of respondents identifying "almost right, but not quite" as the dominant frustration (Stack Overflow, 2025). The METR randomized controlled trial found that experienced open-source developers were 19% slower when using AI tools, despite self-reporting a 20% speedup—a systematic overestimation of productivity that underscores the gap between generation quantity and verification quality (Becker et al., 2025). The study recruited 16 experienced developers from large open-source repositories averaging 22,000 or more stars and randomized 246 real issues, making it the most rigorous productivity measurement available. Tihanyi et al. (2025) found that at least 62% of AI-generated code changes contained security vulnerabilities, with vulnerability patterns correlated across samples. The GitHub Octoverse 2025 report records 986 million commits processed in a single year, a 25% year-over-year increase driven substantially by AI-assisted workflows (GitHub, 2025). Taken together, these findings describe a system producing code at unprecedented volume while the mechanisms for establishing trust in that code lag behind.
This paper argues that meeting this challenge requires not better models but institutional redesign: new architecture patterns that optimize for parallel verifiability (Section 3), new process models centered on specification compilation and evidence production (Section 4), recognition that historical precedents in VLSI, genomics, and distributed computing have already confronted and partially solved the parallel verification problem (Section 5), honest accounting of the new constraints that replace old ones (Section 6), a vision for agent-native software engineering (Section 7), and rigorous attention to catastrophic failure modes including correlated model failure, Goodhart's Law applied to automated metrics, and specification ambiguity amplification (Section 8).
1.5 Contributions
This paper makes the following contributions:
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We excavate the human-centric assumptions embedded in software engineering's foundational principles and demonstrate that each encodes constraints that dissolve or transform at agent scale (Section 2).
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We introduce the concept of Protocol-Imprinted Architecture (PIA): in agent-scale development, software topology mirrors orchestration protocol topology rather than organizational communication structure, transforming Conway's Law from an organizational observation to a coordination design principle (Section 2, with implications developed in Section 7).
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We formalize the delivery latency decomposition (Equation 1) and demonstrate that the optimization target shifts from to as agent count increases (Section 1).
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We introduce twelve novel concepts comprising six formal metrics—Spec Throughput Ceiling (STC), Coupling Tax Curve (CTC), Agent-Parallel Fraction (APF), Divergence Budget, Coordination Surface Area (CSA), and Verification Throughput (VT)—and six theoretical frameworks—Protocol-Imprinted Architecture (PIA), Evidence-Carrying Patch (ECP), Specification Elasticity, Intent Drift, Code Stigmergy, and the Shannon Limit of Software—that together provide a measurement and design framework for agent-scale development (consolidated in Table 11, Section 9).
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We synthesize cross-domain precedents from VLSI/EDA, genomics, MapReduce, biology, and military doctrine to establish that massive parallelism produces convergent design solutions across domains (Section 5).
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We present a balanced risk taxonomy encompassing ten catastrophic failure modes, historical automation warnings (4GL, CASE, MDE), and a game-theoretic analysis of multi-agent resource contention (Section 8).
2. Foundations: What We Built for Humans
2.1 Thesis
The discipline of software engineering rests upon a foundation of laws, heuristics, and organizational principles formulated in response to a single immutable constraint: software is built by humans. This section excavates the human-centric assumptions embedded in these principles and examines what happens to each when the implementing workforce shifts from small teams of expensive, cognitively limited humans to large swarms of cheap, stateless agents. We demonstrate that, in every case we have examined, each foundational principle encodes assumptions about human cognition, cost, or social dynamics. These principles were correct responses to the constraints of their era, but they are laws of human-scale software development, not laws of software development per se.
2.2 Brooks' Law: A Law of Human Communication
In 1975, Frederick P. Brooks Jr. observed that "adding manpower to a late software project makes it later" (Brooks, 1975, p. 25). Brooks identified three compounding costs: ramp-up time for new team members, communication overhead growing as pairwise channels, and task indivisibility along the critical path. For a team of 10, the formula yields 45 communication channels; for 50, it yields 1,225; for 1,000—the scale at which agentic systems now operate—it yields 499,500. At human communication bandwidth, this is catastrophically unworkable.
Brooks' Law shaped the entire trajectory of software engineering practice. Small teams ("two-pizza teams"), modular architecture, Scrum ceremonies, documentation practices, and code review processes are all strategies for managing the problem (DeMarco and Lister, 1987).
The formula assumes that communication channels are expensive because human communication is slow, lossy, ambiguous, and asynchronous. Each property changes fundamentally with AI agents. Ramp-up time approaches zero: an agent parses an AST, reads documentation, and indexes symbols in seconds rather than weeks. Communication overhead restructures: agents coordinate through shared state—what biologists call stigmergy—rather than pairwise channels (Dorigo et al., 2000). The communication complexity drops from to : each of agents reads from and writes to a shared environment. Task indivisibility remains, but the serial portion compresses: an agent produces a contract, writes it to shared state, and implementing agents begin work within milliseconds rather than after a multi-day RFC process.
The implication is that Brooks' Law is primarily a law of high-latency, lossy communication rather than a law of software development per se. It is a law of human software development. In a world of agents, adding agents to a project can genuinely accelerate it, provided the work is decomposable and the coordination mechanism is stigmergic rather than pairwise.
2.3 Conway's Law Becomes Protocol-Imprinted Architecture
Conway (1968) proposed that "any organization that designs a system will produce a design whose structure is a copy of the organization's communication structure." This observation has been validated empirically: MacCormack, Rusnak, and Baldwin (2012) found strong correlations between organizational structure and software modularity across multiple products, and Colfer and Baldwin (2016) confirmed the "mirroring hypothesis" while cataloging boundary conditions.
Conway's Law presupposes that an organization's communication structure is constrained—that silos, bottlenecks, and asymmetries exist. When the "organization" is 1,000 AI agents coordinated through a shared state backend, the communication structure becomes uniform: every agent has identical access to every piece of shared state. There are no organizational silos, no information asymmetries, no "that's another team's code" gatekeeping. Conway's Law, applied literally, predicts either a monolith (no communication boundaries yield no architectural boundaries) or something new.
We propose that what emerges is Protocol-Imprinted Architecture (PIA): in agent-scale development, software topology mirrors the orchestration protocol topology rather than the organizational communication structure. The "communication structure" of an agent swarm is shaped by the coordination protocol: what is in the task queue, what is in the specification, what shared context is available, and what verification gates are imposed. If the task decomposition assigns Agent Group A to the payment module and Agent Group B to the notification module, those boundaries manifest in the software. Conway's Law transforms from "software mirrors org charts" to "software mirrors orchestration protocol graphs."
This transformation is not merely terminological. It has a practical consequence: architecting the agent protocol graph becomes architecting the software. The design of the coordination protocol—task decomposition grammar, tool permission model, verification policy, merge strategy—directly determines the resulting software architecture (see Section 3 for architectural implications and Section 7 for the full development of PIA in agent-native engineering).
2.4 Team Topologies and the Dissolution of Cognitive Load
Skelton and Pais (2019) organized their influential framework around a single foundational principle: cognitive load. Drawing on Miller's (1956) finding that human working memory holds approximately items and Sweller's (1988) cognitive load theory, they argued that teams have a fixed "cognitive budget" and that organizational design should minimize extraneous load while carefully budgeting intrinsic and germane load.
The cognitive load framework drove architectural decisions throughout the 2020s. Platform teams existed to absorb infrastructure complexity so that stream-aligned teams could focus on business logic. Complicated-subsystem teams existed because specialist knowledge (video codecs, ML inference pipelines, cryptographic libraries) would overwhelm a generalist team's cognitive budget. API boundaries were cognitive boundaries: a well-designed API reduces the load required to use the service behind it.
AI agents do not have a cognitive budget of items. A modern LLM processes 128,000 to 2,000,000 tokens of context—equivalent to an entire medium-sized codebase. Platform teams become unnecessary: an agent reads Kubernetes documentation, writes deployment manifests, and debugs rollouts within a single context window. Complicated-subsystem teams dissolve: an agent can be instantiated with specialist knowledge of both the video codec and the broader system. Enabling teams transform from multi-week coaching engagements to context injections.
However, a new constraint emerges that is analogous but not identical: context window limits. While vastly exceeding human working memory, context windows are still finite, and effective utilization degrades before the window is exhausted—the "lost in the middle" phenomenon (Liu et al., 2024). At sufficient scale (codebases of tens of millions of lines), context windows become binding. The field may require a "Context Window Topologies" framework—one that decomposes systems into context-window-sized modules rather than cognitive-load-sized teams (see Section 6 for a full treatment of new constraints replacing old ones).
2.5 The "Expensive Engineer" Assumption
The single most powerful force shaping software architecture for the past fifty years has been the cost of the human engineer. With median total compensation for US software engineers ranging from approximately $120,000 to $450,000 or more at senior levels (Bureau of Labor Statistics, 2025; levels.fyi, 2025), and fully-loaded costs adding 30–50%, a team of ten senior engineers at a major technology company represents a $5–7 million annual expenditure. This expense drove every major architectural pattern:
Microservices (Lewis and Fowler, 2014) reduced coordination costs by drawing service boundaries along team boundaries. The distributed systems tax—network calls, eventual consistency, service mesh complexity—was accepted because it was cheaper than the coordination cost of large teams working on a monolith. When agents coordinate through shared state rather than meetings, the coordination-avoidance benefit evaporates but the architectural tax remains.
DRY (Hunt and Thomas, 1999) eliminated duplication because human maintenance is expensive. Finding and updating five instances of a duplicated business rule costs hours of engineer time and risks defects when one instance is missed. For agents, duplication is nearly free to maintain: an agent greps the entire codebase, updates all instances consistently, and verifies the result in seconds. The economic justification weakens while the coupling cost of aggressive deduplication persists (see Section 3 for the full DRY paradox analysis).
Abstraction layers (ORMs, service layers, dependency injection) reduced cognitive load at the cost of indirection, debugging difficulty, and performance overhead. These costs were acceptable because the cognitive load reduction was worth it for humans. For agents that can hold an entire codebase in context and trace execution paths without confusion, many abstractions become pure overhead.
Module boundaries followed Conway's Law: they mirrored team boundaries. With agents, module boundaries can follow domain boundaries directly, achieving the aspiration of Domain-Driven Design (Evans, 2003) without the compromise imposed by organizational politics.
The inversion is summarized in Table 2.
2.6 Amdahl's Law Applied to Software Development
Amdahl (1967) described the theoretical maximum speedup from parallelizing a computation:
where is the speedup with parallel workers, is the parallelizable fraction of total work, and is the serial fraction. The law reveals that if even 5% of work is serial, the maximum speedup with infinite workers is capped at 20x. If 10% is serial, the cap is 10x.
Applied to traditional software development, a rough decomposition of effort yields approximately 25% serial work: requirements gathering (10–15%, mostly serial), architectural design (5–10%, partially parallel), integration (5–10%, mostly serial at boundaries), and deployment (2–5%, serial). If 25% of software development effort is serial, Amdahl's Law predicts a maximum theoretical speedup of 4x from parallelization alone—regardless of how many engineers are added. This aligns with empirical experience: doubling a team from 5 to 10 rarely doubles output (Brooks, 1975; Sackman et al., 1968).
Agents do not merely add parallelism to the parallelizable portion; they compress the serial portion itself. Requirements analysis parallelizes: multiple agents simultaneously research feasibility, analyze similar systems, identify edge cases, and draft acceptance criteria. Architectural design accelerates: agents prototype multiple approaches in parallel and synthesize in minutes rather than days. Integration becomes near-instantaneous when agents produce code conforming to shared specifications and test suites. Code review is replaced by parallel automated verification: static analysis, type checking, mutation testing, and semantic analysis run concurrently.
If the serial fraction drops from 25% to 5%, the theoretical maximum speedup jumps from 4x to 20x. If it drops to 2%, the ceiling reaches 50x. This is the regime in which 1,000-agent orchestration systems become theoretically justified.
Figure 2. Amdahl's Law curves for varying parallelizable fractions. The plot shows theoretical speedup as a function of agent count for four parallelizable fraction values (where is the serial fraction): (traditional human development, serial fraction 25%, max 4x), (optimistic human development, serial fraction 10%, max 10x), (agent-compressed serial fraction 5%, max 20x), and (highly optimized agent orchestration, serial fraction 2%, max 50x). The curves demonstrate that compressing the serial fraction —not merely increasing parallelism—is the key to unlocking agent-scale speedup. Beyond approximately 100 agents, further scaling yields diminishing returns unless the serial fraction is simultaneously reduced.
Gustafson (1988) offered a complementary perspective. Where Amdahl assumed a fixed problem size, Gustafson assumed a fixed time budget and asked how much more work could be done:
where is the serial fraction. With 1,000 agents, organizations do not simply build the same feature 1,000 times faster—they build a system with 1,000 times more tests, more edge-case handling, more documentation, and more feature variants. Gustafson's framing suggests that agent abundance will expand the definition of "complete" software rather than merely accelerate the delivery of today's definition.
2.7 The Foundation Inversion
Table 2 synthesizes the preceding analysis. In every case we have examined, the foundational principles of software engineering encode human constraints that dissolve or transform at agent scale.
Table 2. The foundation inversion: human principles and their agent-era reality.
| # | Foundational Principle | Human Assumption | Agent-Era Reality |
|---|---|---|---|
| 1 | Brooks' Law | Communication overhead is and expensive | Stigmergic coordination is via shared state |
| 2 | Conway's Law | Software mirrors organizational structure | Software mirrors orchestration protocol topology (PIA) |
| 3 | Team Topologies | Cognitive load ( items) must be managed | Context windows (128K–2M tokens) vastly exceed human memory; new "context window topologies" constraint emerges |
| 4 | DRY principle | Duplication is expensive to maintain | Maintenance is cheap; coupling-induced serialization is the greater cost |
| 5 | Microservices | Small teams need small, autonomous services | Team coordination overhead is substantially reduced; the distributed-systems tax becomes unnecessary overhead |
| 6 | Abstraction layers | Cognitive load reduction justifies indirection cost | No cognitive load constraint; indirection is pure overhead |
| 7 | Module boundaries | Boundaries follow team boundaries (Conway) | Boundaries follow domain boundaries directly (DDD aspiration realized) |
| 8 | Code ownership | Accountability plus territorial social dynamics | No ego, no territory; accountability via immutable audit trails |
| 9 | 10x engineer / bus factor | Talent variance is massive; knowledge concentrates | Performance variance is reduced compared to human teams, though model-specific biases and prompt sensitivity introduce new variance dimensions; knowledge resides in shared state |
| 10 | Amdahl's Law | Serial fraction is approximately 25% (max 4x speedup) | Serial fraction compressible to approximately 5% (max 20x speedup) |
This table does not argue that these principles were wrong. They were correct responses to the constraints of their era. But they are not laws of physics—they are laws of human-scale software development. As the implementing workforce changes from humans to agents, the entire foundation must be re-examined.
The following sections explore what a software engineering discipline built for agent-scale development requires: new architectural patterns optimized for parallel throughput rather than human comprehension (Section 3), new process models centered on specification and verification rather than implementation (Section 4), cross-domain precedents demonstrating that these challenges have been confronted before (Section 5), and an honest accounting of the new constraints that replace the old (Section 6).
3. Architecture for Agent-Scale Development
The previous section established that software engineering's foundational assumptions encode human constraints. This section addresses the central technical question: how must software architecture change when the optimization target shifts from human comprehension to parallel throughput? We argue that agent-scale development requires a fundamental reorientation of architectural principles, introduce formal metrics for measuring parallelizability, and show that several classical heuristics—most notably DRY—become counterproductive at scale.
3.1 The DRY Paradox: When Coupling Is Worse Than Duplication
The DRY (Don't Repeat Yourself) principle, formalized by Hunt and Thomas (1999), states that "every piece of knowledge must have a single, unambiguous, authoritative representation within a system." DRY exists because of a specific economic calculation: when a human must maintain duplicated code, the cost of finding and updating every copy exceeds the cost of the indirection introduced by abstraction. The justification rests on two human-specific failure modes: developers forget which copies exist, and they miss copies during updates.
With AI agents, these failure modes change character. An agent instructed to update all implementations of a given algorithm can search the entire codebase in seconds, identify every copy, and update them in parallel. The "forgotten copy" failure mode that is the primary economic justification for DRY essentially disappears. Meanwhile, the cost of DRY's alternative—abstraction and coupling—increases dramatically.
Formal analysis. Let denote the number of active agents, the parallelizable fraction of total work, and the serial fraction. The Amdahl-style upper bound (Amdahl, 1967) gives:
As , . DRY reduces local code volume but increases because shared abstractions create high-fan-in dependency chokepoints. Every shared abstraction is a dependency edge in the module graph; every dependency edge constrains parallelism.
Consider a utility function formatCurrency() used by fifty modules. Under DRY, all fifty depend on a shared utility module. If that function needs modification, all fifty dependent modules are potentially affected, creating a serialization point. Under the alternative—each module containing its own implementation—there are no dependency edges. Fifty agents can each update their local copy simultaneously. The total work is fifty times larger, but the wall-clock time is the same as updating one copy.
We formalize this comparison as:
where is the time to modify the shared component, captures coordination overhead, captures queueing delay when agents contend for the shared resource, is the cost of integration testing across all dependents, and is the marginal per-copy duplication overhead. The term represents the per-agent verification cost: each of the agents runs its own local verification in parallel, so the total compute cost is , but the wall-clock contribution is only because all verifications execute simultaneously. This model compares delivery latency (wall-clock time to completion), not total compute cost; it assumes verification infrastructure scales linearly with agent count.
A sufficient condition for duplication to dominate is:
This is conservative: the exact crossover depends on the correlation structure between and across agents, because in general, with equality only when the same agent maximizes both terms. The sufficient condition is satisfied more frequently as grows, because and scale with contention while and remain constant per agent in wall-clock terms.
The "Spec-DRY, Code-WET" principle. Rather than abandoning DRY entirely, we propose a nuanced restatement: maintain one canonical specification, but allow many local implementations. Specifications must remain deduplicated because ambiguity propagates multiplicatively (Section 4.1). Implementations can be duplicated when the coupling cost of deduplication exceeds the maintenance cost of copies.
Table 4. Where DRY is non-negotiable vs. where WET is superior.
| Domain | Regime | Rationale |
|---|---|---|
| Security-critical invariants (auth, crypto) | DRY non-negotiable | Correctness paramount; divergent copies introduce audit-defeating variance |
| Compliance and regulatory logic | DRY non-negotiable | Legal liability demands single auditable source |
| Financial calculation kernels | DRY non-negotiable | Rounding and precision errors compound across copies |
| Adapter and edge layers | WET preferred | Low complexity; coupling cost exceeds duplication cost |
| Bounded context glue code | WET preferred | Feature-local; rarely changes after initial implementation |
| Feature-local workflow logic | WET preferred | Scope-bounded; agents regenerate rather than maintain |
| Infrastructure boilerplate | WET preferred | Template-driven; trivially regenerated from specification |
The analogy to database design is precise. Relational normalization eliminates data duplication at the cost of requiring joins. Denormalization introduces duplication but eliminates joins, improving read performance. The choice depends on the read/write ratio. Similarly, code deduplication eliminates implementation duplication at the cost of introducing coupling. The decision depends on the parallelism/maintenance ratio—and at agent scale, that ratio shifts decisively toward parallelism.
Figure 3. vs. cost comparison.
A plot showing two curves: increasing with due to coordination and queue costs that scale with contention, and remaining approximately flat because per-copy duplication overhead does not grow with agent count. The curves cross at a critical agent count (approximately 15–30 for typical codebases), beyond which WET dominates. Shaded regions indicate domains where DRY remains non-negotiable regardless of .
Evidence from the agentic systems literature supports this analysis. AFlow (2024) and Flow (2025) explicitly optimize agent workflow modularity and dependency complexity. Agentless (Xia et al., 2024), which eschews complex agent scaffolding in favor of simpler decomposition, outperformed more elaborate agent frameworks on SWE-bench—suggesting that over-orchestration overhead, which DRY-induced coupling amplifies, is a real and measurable cost.
3.2 Dependency Graphs as the Critical Bottleneck
If the DRY paradox reveals the hidden cost of coupling, dependency graph analysis reveals the structural constraint that coupling imposes. The maximum parallelism achievable for any task is determined by the critical path of its dependency graph—the longest chain of sequentially-dependent operations. This chain sets a hard floor on completion time regardless of agent count.
Build systems understood this decades ago. Bazel and Buck construct fine-grained dependency DAGs and execute leaf nodes in parallel, propagating completion notifications upward. The critical path determines minimum build time regardless of worker count. The same analysis applies to implementation tasks: if module A depends on module B depends on module C, these three modules must be implemented sequentially even with a thousand available agents.
Critical path reduction. Several techniques reduce critical path length:
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Contract extraction. Replacing implementation dependencies with contract dependencies breaks sequential chains. If A depends on B's interface (not B's implementation), both A and B can proceed in parallel against the shared contract. This transforms a dependency graph edge from a sequential constraint into a parallel opportunity.
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Dependency inversion. Both A and B depend on an abstraction (interface) rather than A depending on B directly. The interface is defined first—a trivial task—and then both implementations proceed in parallel. This applies the Dependency Inversion Principle (Martin, 2003) but motivated by parallelism rather than flexibility.
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Graph widening. Restructuring a deep chain (A B C D, depth 4) into a wide, shallow graph (interface first, then B, C, D in parallel; depth 2) shrinks the critical path from four to two.
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Stub generation. An agent generates a stub implementation matching the type signature, enabling dependent modules to proceed against the stub. The real implementation replaces the stub later.
Dependency width. We introduce dependency width as a new metric: the width of the widest antichain in the dependency DAG. An antichain is a set of nodes with no dependency relationships between them—they can all be executed in parallel. A system with high coupling but high dependency width (many modules depending on a shared core but not on each other) is more parallelizable than a system with low coupling but low dependency width (modules arranged in a long chain). This challenges the traditional assumption that low coupling always produces better architecture. For parallelism, the arrangement of coupling matters more than its quantity.
Figure 4. Dependency graph transformation.
Left: A deep-and-narrow dependency graph with critical path length 7 and maximum dependency width 3. Right: The same system after graph widening via contract extraction, with critical path length 3 and maximum dependency width 12. Shaded nodes represent contract/interface definitions that must complete before parallel implementation begins. The transformation increases useful parallelism by approximately 4x.
3.3 Architecture Patterns That Enable Massive Parallelism
We identify six architecture patterns that exhibit high parallelizability scores, drawing on both the parallelism-enabling patterns literature (Parnas, 1972; Stonebraker, 1986) and empirical evidence from production multi-agent systems.
Wide-and-shallow over deep-and-narrow. The single most impactful decision is preferring breadth over depth in the module dependency graph. A system with one hundred independent modules that each depend only on a thin shared core can have all one hundred modified simultaneously. A system with the same complexity organized as twenty deeply-nested layers can only be modified one layer at a time. This principle extends to API design: wide APIs with many independent endpoints are more parallelizable than GraphQL resolvers chaining through shared data loaders.
Event-sourced architectures. Event sourcing—storing state as an append-only sequence of immutable events rather than as mutable current state—creates a natural substrate for massive parallelism. Agents can work on independent events without coordination; appends do not conflict because they are commutative. Reconstruction of current state from the event log is a pure function. Event sourcing also enables checkpoint-and-replay for fault recovery.
Cell-based architecture. Cell-based architecture partitions a system into independent cells, each containing a complete vertical slice of functionality. If a system comprises fifty cells, a change to authentication logic can be implemented by fifty agents simultaneously, each modifying one cell. The specification is written once; the implementation is replicated across cells. This is data parallelism in its purest form applied to software construction. The pattern also provides natural blast-radius containment: if an agent introduces a bug in one cell, only that cell's users are affected.
Plugin architectures. When the core is small and stable, plugin boundaries become natural parallelization seams. A plugin architecture with two hundred plugins can have all two hundred developed simultaneously, provided the plugin interface contract is well-defined. The upfront cost of designing a good plugin API is repaid many times over in implementation parallelism. The plugin pattern exhibits an important coupling profile: plugins have high efferent coupling () toward the core but zero coupling toward other plugins (Parnas, 1972).
Specification-driven development. Cursor's engineering blog on self-driving codebases (2026; non-archival) identified specifications as the single most important leverage point at scale, a finding consistent with the monorepo literature's emphasis on tooling-enforced consistency (Potvin and Levenberg, 2016). When an ambiguous specification is distributed to one hundred agents, it produces one hundred different interpretations, each requiring reconciliation. Specification-driven development inverts the traditional relationship: the specification is the architecture. Given a sufficiently precise specification, the implementation becomes a deterministic mapping—and deterministic mappings are trivially parallelizable.
Contract-first design. Defining interfaces before implementations is a prerequisite for massive parallelism. If the interface between modules A and B is defined as a TypeScript interface or OpenAPI specification before either is implemented, both implementations proceed in parallel with zero coordination. The deeper insight is that contract-first design transforms a dependency graph edge from a sequential constraint into a parallel opportunity. Every edge that can be replaced with a contract edge is an edge that no longer constrains the critical path.
3.4 New Architecture Metrics
Traditional architecture metrics—cyclomatic complexity, afferent/efferent coupling, instability, abstractness—measure qualities relevant to human comprehension (Martin, 2003). Agent-scale architectures require metrics that measure parallelizability directly.
Table 3. New architecture metrics for agent-scale development.
| Metric | Formula | Target Range | Measures |
|---|---|---|---|
| Parallelizability Score (P-score) | for agent-scale | Maximum useful agent count | |
| Conflict Probability | per commit cycle | Contention risk (birthday-paradox model) | |
| Independence Ratio | – | Upper bound of coordination-free parallelism | |
| Critical Path Length (CPL) | Longest chain in dependency DAG | regardless of module count | Irreducible sequential core |
Parallelizability Score (P-score). The P-score of a task decomposition is the ratio of total work to critical-path work. A P-score of 1.0 means the work is entirely sequential; a P-score of 100 means the work can be divided among 100 agents with no idle time. The P-score depends on both system architecture and decomposition quality.
Conflict Probability. Given agents working simultaneously on a codebase with files, each modifying files chosen uniformly at random, the probability that at least two agents modify the same file follows birthday-paradox statistics. The derivation proceeds as follows: let denote the total number of file-touches across all agents. Treating each touch as an independent draw from files, the probability that no two touches land on the same file is . Applying the standard logarithmic approximation for small :
where the final step uses for large . Therefore:
Assumptions: file selections are uniformly random and independent across agents; intra-agent file selections do not repeat. We emphasize that Equation (8) represents a lower bound on conflict probability. Real codebases exhibit Zipfian (power-law) file access patterns—configuration files, shared types, route definitions, and test fixtures are modified far more frequently than leaf modules. Under Zipfian access with exponent , effective shrinks to a small fraction of the nominal file count, and conflict probability at approaches certainty even for large codebases. A conflict rate significantly above the birthday-paradox baseline indicates architectural problems (hot files, inadequate decomposition); a rate below the baseline indicates effective file-ownership partitioning. Note that Equation (8) models file-level collision probability, which is a necessary but not sufficient condition for semantic merge conflict. Two agents modifying the same file may edit disjoint functions (no semantic conflict), while two agents modifying different files may break a shared API contract (semantic conflict despite no file collision). The actual merge-conflict rate is therefore architecture-dependent.
[Table 3a: Sensitivity Analysis—Conflict Probability ]
| , | 0.36 | 0.71 | 0.99 |
| , | 0.09 | 0.22 | 0.63 |
| , | 0.04 | 0.12 | 0.39 |
| , | 1.00 | 1.00 | 1.00 |
| , | 1.00 | 1.00 | 1.00 |
| , | 0.99 | 1.00 | 1.00 |
| , | 1.00 | 1.00 | 1.00 |
| , | 1.00 | 1.00 | 1.00 |
| , | 1.00 | 1.00 | 1.00 |
Values computed as , rounded to two decimal places. At , conflict is virtually certain for any realistic and , confirming that conflict resolution is the normal operating mode at agent scale, not an edge case.
Independence Ratio. The fraction of modules with zero cross-module dependencies. A system with independence ratio 0.80 means 80% of modules can be modified without considering any other module, directly predicting the upper bound of coordination-free parallelism. Human-designed systems typically exhibit independence ratios of 0.10–0.30; agent-scale architectures should target 0.60–0.80.
Critical Path Length (CPL). The longest dependency chain sets the theoretical minimum number of sequential steps for any system-wide change: . Reducing CPL by one level increases maximum useful parallelism by a factor proportional to the graph width at that level.
We now formally define four novel concepts that emerge from this analysis.
Definition 1 (Coupling Tax Curve). The Coupling Tax Curve is a function mapping dependency density (edges per node in the module dependency graph) to the fraction of theoretical parallel speedup lost to coordination overhead. For a given architecture with dependency density and agents, the realized speedup is:
CTC captures the insight that coupling creates serialization pressure beyond what Amdahl's Law alone predicts, because contention for shared resources introduces queueing delays and coordination overhead that compound with both density and agent count. The functional form of CTC requires empirical calibration from multi-project data; we conjecture a sigmoidal shape: where is the inflection point and controls steepness. As a hypothetical illustration: a codebase with (average 2 dependency edges per module) might exhibit , meaning 30% of Amdahl speedup is lost to coordination; at , CTC might rise to . Precise calibration from production multi-agent systems is an important direction for future work.
Definition 2 (Agent-Parallel Fraction). The Agent-Parallel Fraction is the proportion of a backlog that is executable independently under frozen contracts:
where denotes the set of interface contracts that have been committed to the canonical specification repository and are not subject to concurrent modification during the current execution window. Operationally, a contract is "frozen" when its interface definition (e.g., TypeScript interface, OpenAPI schema, or protobuf definition) has been merged to the canonical branch and no pending task modifies it.
APF predicts achievable acceleration from agent count growth. An APF of 0.90 means that 90% of backlog items can be executed in parallel given stable contracts; the remaining 10% require sequential resolution of contract changes.
Definition 3 (Divergence Budget). The Divergence Budget is a formal allocation for independent deviation in module before reconciliation is required. It is defined as the maximum number of concurrent, unreconciled changes permitted before the expected merge conflict rate exceeds a threshold :
The divergence budget is measured over a fixed commit-cycle window , using the birthday-paradox estimator of Equation 8 with the assumption that is monotonically non-decreasing in . This monotonicity ensures that DB is well-defined as the largest satisfying the threshold. The divergence budget operationalizes the tradeoff between parallelism (allow more concurrent changes) and coherence (require frequent reconciliation).
Definition 4 (Coordination Surface Area). The Coordination Surface Area of a task decomposition is the number of edges in the task dependency graph:
Lower CSA implies less inter-task coordination overhead. A decomposition that produces 100 tasks with CSA = 5 (five dependency edges) is dramatically more parallelizable than one with 100 tasks and CSA = 200, even if the total work volume is identical. CSA should be minimized subject to correctness constraints.
4. Process Transformation
Having established the architectural requirements for agent-scale development, we now examine how the software development lifecycle must transform when implementation is no longer the rate-limiting step. The central claim is that the bottleneck shifts from code production to specification quality, verification throughput, and merge coherence—a shift that demands new processes, new metrics, and new roles.
4.1 The Specification Bottleneck
The OpenAI SWE-bench Verified project provides direct evidence for the specification bottleneck: 93 experienced developers were needed to re-annotate 1,699 benchmark samples because underspecification and test quality issues distorted evaluation (OpenAI, 2025). The problem was not model capability but specification quality—the precision with which tasks were defined determined whether solutions could be evaluated correctly.
The amplification problem. When one developer misunderstands a requirement, one feature goes wrong. When a thousand agents misunderstand a specification, a thousand features go wrong simultaneously, and the reconciliation cost is catastrophic. Cursor's research on self-driving codebases (2026) confirmed this empirically: vague specifications produce exponentially amplified misinterpretation as they propagate across hundreds of worker agents.
This amplification effect motivates the concept of a specification compilation pipeline—a systematic process for converting human intent into machine-executable precision:
- Intent capture. Human articulates strategic intent in natural language.
- Formalization. LLM-assisted compilation into structured specifications with measurable acceptance criteria.
- Adversarial QA. One set of agents drafts the specification; another set attempts to find ambiguities and contradictions.
- Verified specification. The specification is validated for completeness and machine-checkability.
- Parallel implementation. Agent fleet executes against the verified specification.
- Verification. Automated verification pipeline confirms conformance.
Definition 5 (Spec Throughput Ceiling). The Spec Throughput Ceiling is the maximum rate at which an organization can produce unambiguous, machine-checkable task specifications:
The STC is the true delivery limit in agent-scale development. No matter how many agents are available, delivery throughput cannot exceed the capacity of the tightest pipeline stage.
4.2 Verification as the New Core Discipline
Traditional code review assumes a ratio of roughly one reviewer per one to five pull requests. At agent scale, 1,000 simultaneous agents may each produce independent pull requests within minutes. Even with dedicated reviewers working full-time, the mathematics are prohibitive. The solution is not faster review but automated verification with human oversight reserved for genuinely novel decisions.
Definition 6 (Verification Throughput). Verification Throughput is the rate at which correctness can be established for submitted changes:
When , verification becomes a bottleneck and unverified changes accumulate. Sustainable agent-scale development requires continuously.
4.3 Version Control at 1,000 Agents
Git was designed for human-speed collaboration. At agent scale, every assumption breaks. The conflict probability (Equation 8) approaches certainty.
Optimistic merging as default. Experience from production agent orchestration systems and Cursor's engineering reports (2026; non-archival) suggests that pessimistic file-level locking creates precisely the contention it is meant to prevent. The alternative is optimistic execution with periodic reconciliation.
Definition 7 (Intent Drift). Intent Drift is the cumulative deviation between the original specification intent and the implemented result after generations of agent changes:
where is a semantic distance function. Intent drift accumulates across agent generations even when each individual change is locally correct, because small deviations compound.
5. Cross-Domain Precedents
The challenge of coordinating massive parallelism against a complex artifact is not unique to software engineering. Other domains—semiconductor design, genomics, distributed computing, biology, and military command—have confronted structurally identical problems and arrived at convergent solutions.
VLSI/EDA: The history of Electronic Design Automation (EDA) is the single most instructive analogy. The industry discovered that the route to scaling was not designing more but composing more from pre-verified building blocks (IP reuse) and that verification becomes the dominant cost (50–70% of effort).
Genomics: The Human Genome Project demonstrated that both hierarchical and flat decomposition strategies work, but aggregation algorithms (assembly) are critical infrastructure.
MapReduce: Demonstrated that fault tolerance must be a first-class design concern and that the "reduce" phase is where hard engineering lives.
Biology: Morphogenesis and stigmergy demonstrate parallel construction from specification and indirect coordination. We propose the term Code Stigmergy for the software engineering analogue: indirect coordination among agents via traces left in the shared codebase environment.
Military Command: Auftragstaktik (mission-type tactics) specifies intent rather than method, mapping directly to specification-driven agent orchestration.
6. New Constraints Replacing Old Ones
Agent-scale development does not eliminate constraints; it substitutes one set for another.
Context Windows as Cognitive Load: Context windows (128K–1M tokens) replace human working memory (7 items). This drives a new unit of decomposition: the context-window-sized module.
Hallucination and Correlated Failure: Agents exhibit "hallucination" and "naming drift." More dangerously, homogeneous fleets exhibit correlated failure modes, creating monoculture vulnerabilities.
The Coordination Tax: Coordination cost scales with agent count. Amdahl's Law applies to coordination overhead.
Cost Economics: Agents shift labor from fixed cost (salary) to variable cost (tokens), creating a model routing problem.
Knowledge Cutoff: Agents lack institutional memory, requiring explicit context engineering for every invocation.
The Shannon Limit of Software: We propose a structural analogy to channel capacity:
where is code production rate and is verification capacity. When , the system enters entropy collapse.
7. Agent-Native Software Engineering
We propose a new discipline based on:
- Specification Is the Product: Code is a derived build artifact; specification is the source of truth.
- Architecture Patterns: The Thousand-Agent Monolith (hierarchical), The Swarm Pattern (emergent), and The Factory Pattern (pipeline).
- New Roles: Specification Engineers, Verification Engineers, Architecture Engineers, Orchestration Engineers.
- Formal Methods Renaissance: Agent abundance inverts the economics of formal verification.
- Evidence-Carrying Patch (ECP): A code change bundled with structured evidence of correctness (proofs, tests, provenance).
8. Risks and Failure Modes
We identify ten catastrophic failure modes, including Spec Ambiguity Amplification, Correlated Model Failure, Verification Theater, and Goodhart's Law Degradation. The Epistemology Problem (software correctness becomes statistical rather than deductive) and Strategic Deskilling (humans lose the ability to debug the system) are critical long-term risks.
9. Research Agenda
We propose a research agenda focused on Metrics for a New Discipline (STC, CTC, APF, ECP, PIA), Unsolved Questions (The Halting Problem of Agency, Semantic Drift, ACI design), and Institutional Redesign.
10. Conclusion
Software engineering is undergoing a phase change from human-limited scarcity to agent-enabled abundance. The bottleneck shifts from implementation to specification, verification, and coordination. Success requires not just better agents, but a fundamental redesign of architecture, process, and institutions to manage trust scarcity in an age of code abundance.
References
(Selected references)
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- Anthropic. (2025). Building effective agents.
- Becker, et al. (2025). Engineering with Large Language Models: A Randomized Controlled Trial.
- Brooks, F. P. (1975). The Mythical Man-Month.
- Conway, M. E. (1968). How do committees invent?
- Cursor. (2026). Self-driving codebases.
- Google Cloud. (2025). 2025 State of DevOps Report.
- Hunt, A., & Thomas, D. (1999). The Pragmatic Programmer.
- OpenAI. (2025). SWE-bench Verified.