# 025. A Claude process holds its task folder open

## Measured

2026-10-30, Claude Code 2.1.310 and 2.1.314, on Linux (Debian 13, x64).
Two live interactive sessions in tmux. `readlink` read each entry of
`/proc/<pid>/fd`.
Measured on: real machine.

## What was measured

1. A Claude process holds no transcript file open.
2. It holds one folder open:
   `/tmp/claude-<uid>/<project key>/<session id>/tasks`. The session ID in
   that path is the `sessionId` of `~/.claude/sessions/<pid>.json`
   (fact 023).
3. Its other descriptors are its tty (8 descriptors), sockets, and
   `anon_inode` entries (`eventpoll`, `eventfd`, `pidfd`).

## Mechanism

A reader that can read the open files of a process, but not the home
folder of its user, can still get the session ID from the task folder.

## Incident

None.

## Screens

None.

## Not measured

- Whether the folder changes after `/clear`.
- Sessions with no background task. Both sessions had run tasks.
- The path on macOS and Windows, where the temporary folder is different.

## 2026-10-30, 2.1.314: before the first task, and after /clear

Measured on: real machine. Scenario `scenarios/claude/dialog-states.sh`
(three runs) in a throwaway `HOME`, on the same Linux machine.

1. Before the first Bash tool call, the process held no folder below
   `/tmp/claude-<uid>/` open, and the `tasks` folder did not exist. The
   first Bash call made the folder and opened it. That call was a
   foreground `ls`, not a background task (fact 034).
2. After `/clear`, the process still held the `tasks` folder of the first
   session ID. A background task after `/clear` wrote its output there.
   So the session ID in the path is the first session ID of the process,
   not always the `sessionId` of the pid file. The Mechanism above is
   correct only for a process that has had one session (fact 034).