Composer limits, attachments and thinking contract

Intent

A person writes long things. A prompt box that refuses a long paste, hides where a file went, or offers no way to ask for more reasoning is a box that gets in the way of the work.

Contract

Messages. One message may hold up to 200,000 characters. Past 8,000 the interface offers, and does not force, Save as document: the text is stored and the message names its path. Past the maximum the composer refuses before sending, names the limit, and keeps every character in the box. The server answers an over-large message with the limit named, never a schema envelope.

Attachments. Any file can be attached. It is written into the project’s connected repository worktree under docs/uploads/<generated>-<sanitised name> — exclusively, as a regular file, with the name unable to choose a path, and with the size capped before a byte is written. The message carries one line naming every stored path, so an agent reads them through its own contained read. Attachments are uncommitted: they appear in Workspace → Changes and nothing commits or pushes them. A project with no connected worktree is refused with that reason.

Thinking. A session’s thinking level (off, minimal, low, medium, high, xhigh, max, or the host default) is chosen in the composer, stored on that conversation, and reported back by the session view. It cannot be changed while the session is working.

Turns. One dispatch may make DASHBOARD_MAX_MODEL_TURNS model requests in a row (whole number 1–100, default 40, refused rather than clamped when out of range). The refusal names the bound and says that sending another message continues.

Not promised

Attachments are not scanned, converted or executed, and a model that holds neither file_read nor file_edit cannot open one: the message names a path it cannot reach. The interface says that the files were saved for an agent to read; it does not claim the model itself received their bytes.

Acceptance

ID	Evidence
AC-1	A name cannot choose a path, an empty or oversize body is refused before writing, and a project with no worktree is refused.
AC-2	A stored attachment is a regular file inside the worktree, with one generated name.
AC-3	A symlinked uploads directory is refused and nothing is written through it.
AC-4	The message names every stored path.
AC-5	The composer offers the document action past the threshold, refuses past the maximum, and keeps the text.
AC-6	The thinking level is chosen per session and reported back by the server view.