to-ctx

Take what this session has settled — a decision, a research result, a design, an investigation log — and turn it into a durable context file in the right place, so no future session has to rediscover it.

Language: context files are written in the project's documentation language (check neighboring files), which is not necessarily the conversation's language. Chat replies mirror the user.

Steps

Locate the context system: find the project's durable layer and its placement rules — a map file (e.g. contexts/CONTEXT_MAP.md), a docs/ADR convention, or directory READMEs. If the project has its own context-management skill, defer to its rules and use this skill only as the entry point. If no context system exists, propose ONE location to the user before creating anything.
Select what is durable: keep decisions and their reasons, verified facts with sources, discovered constraints, and open questions. Drop process noise — exploration dead ends, tool logs, interim misunderstandings. If part of the content is already persisted (an issue, PR, or another context doc), reference it; never duplicate it.
Match the house style: read one or two neighboring context files first, then mirror their structure, headings, naming and dating conventions.
Place and write the file per the rules; run the map file's placement check before writing, not after.
Report: the chat gets a one-line summary, the file path, and where it sits in the map. If the map file itself must register the new doc, update it in the same change.

Rules

One fact, one home: never create a second source of truth for something already documented — update or reference the existing doc instead.
The repo's own placement rules always win over this skill's defaults.
Do not commit or push; filing the doc is the deliverable, version control stays with the user's workflow.