diff --git a/CLAUDE.md b/CLAUDE.md
index f46ed65..8f0e71f 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -108,6 +108,8 @@ Pass 2 builds `ok_disk_names` — the set of disk names that already match the s
 
 **`selection.json`** — GUI selection state file, tracked in git. Persists which mods/groups are selected between GUI sessions. Written by the GUI; safe to delete (GUI recreates it on next save).
 
+**`run_tool` subprocess streaming:** Tool scripts are launched via `subprocess.Popen` (not `subprocess.run`) with `stdout=PIPE, stderr=STDOUT`, read line-by-line via `iter(proc.stdout.readline, "")`, and posted to the log queue immediately. Python's own output buffering is disabled with the `-u` flag and `PYTHONUNBUFFERED=1` in the environment — without these, output would batch inside the pipe and only appear when the script exits.
+
 ## Python Version Compatibility
 
 Minimum is Python **3.9**. All files that use `X | Y` union type annotations **must** have `from __future__ import annotations` as the first import. Without it, the `|` syntax raises `TypeError` at runtime on Python < 3.10. Every module in `arma_modlist_tools/` already has it; any new CLI script you add must include it too.