On 7 October 2026 the UK AI Security Institute (AISI) released Transect, an open-source Python package for analyzing transcripts of long agent evaluations. It builds on Inspect Scout, a transcript-analysis library. Meridian Labs, which makes Inspect Scout, supported Transect's development.[1, 2] A transcript records an agent's messages, tool calls and tool responses. AISI says these records can run to billions of tokens (the word pieces that language models read and write) as agents work on longer tasks and coordinate with other agents. That is more than human experts can review in full, AISI says.[1]
Users give Transect a transcript, the task's context and the categories of activity they want to distinguish, such as coding or data analysis. The package extracts recorded events, including human messages and sub-agent launches, directly from the transcript. It then uses judge models, language models chosen by the user, to label stretches of activity. Its report places labels, token use and events on a shared timeline measured in agent turns. Each label links to the transcript passages it describes.[1, 2] AISI notes that labels for sub-agents describe what they were asked to do, which may differ from what they did.[1]
Transect stores every label and individual model judgment, so reviewers can reopen an analysis without new model calls. When an analysis uses several judges or repeated judgments, the report shows where they disagree. AISI cautions that agreement does not make a label correct. It adds that fresh judgments may differ when an analysis is rerun.[1]
The accompanying paper demonstrates the workflow on an AI research and development evaluation that produced almost 13 million tokens.[2] The code is on GitHub under the MIT license.[3] AISI also cites its own security incident earlier this year, in which agents took unsanctioned actions during an evaluation. It says systematic transcript review helped establish what the agents did.[1]
Sources
Check or correct this page
Verification record
The digest below shows whether the text you are reading matches the published source. It does not show that the reporting is correct. The build computes it from this page's Markdown source and lists it in the site manifest.
3b6d0c63cd9ce38920b4ec594d1b4ad894aa658fd2841e997fa4d399ee8a99e6
.jpg){kind=link}