diff --git a/.claude/memory/decisions.md b/.claude/memory/decisions.md
index 4ae3c22..9c621cd 100644
--- a/.claude/memory/decisions.md
+++ b/.claude/memory/decisions.md
@@ -33,3 +33,10 @@ Implemented install.sh `setup_remote_desktop` + `ensure_rdp_credentials`. Connec
 Alts rejected: (a) force Xorg GDM + xrdp — sacrifices Wayland desktop, fragile; (b) VNC (wayvnc) —
 RDP preferred (mstsc native on Win client, TLS); (c) g-r-d user "Desktop Sharing" mode — shares
 existing local session, wanted independent headless login. See LRN-004, BLK-004. Status: done.
+
+## BDR-006 — Disk-usage login warning deployed system-wide to /etc/profile.d
+2026-06-24. New `etc/profile.d/disk-usage-warning.sh` (POSIX sh, bold-red warn when / or /home ≥85%)
+deployed via `sudo install -D -m 0644` to `/etc/profile.d/` from `install_disk_warning()`, gated in
+the apt-get Linux block (see LRN-005). Alt rejected: per-user append to `~/.bashrc` — wanted the warn
+for EVERY login account on the box, not just the installing user, so system-wide profile.d won. Known
+limit: login-shell scope only (non-login terminals miss it). Status: done.
diff --git a/.claude/memory/journal.md b/.claude/memory/journal.md
index 1f9ce6e..b9b5cc7 100644
--- a/.claude/memory/journal.md
+++ b/.claude/memory/journal.md
@@ -26,3 +26,9 @@ xrdp abandoned (Wayland-only GNOME kills Xorg session). Replaced install_xrdp 
 empty (BLK-004); 2-layer auth gate→GDM PAM (LRN-004). Added ensure_rdp_credentials (prompt, TTY-guard,
 idempotent). Connection CONFIRMED live. install.sh committed 0bd936b (bash -n + shellcheck CLEAN);
 push blocked here (HTTPS remote, no creds in env) → user pushes. TPM GKeyFile-fallback warn harmless.
+
+## 2026-06-24 — disk-usage login warning
+Added etc/profile.d/disk-usage-warning.sh (POSIX sh, warns bold red when / or /home ≥85%).
+install_disk_warning() in install.sh: sudo install -D -m 0644 → /etc/profile.d, gated in apt block
+(Linux-only: df --output=pcent GNU-only + /etc/profile.d Debian convention). shellcheck + sh -n CLEAN,
+both code paths runtime-verified. README + CLAUDE.md synced. Not committed (master, user to confirm).
diff --git a/.claude/memory/learnings.md b/.claude/memory/learnings.md
index dba1fcd..b7820c0 100644
--- a/.claude/memory/learnings.md
+++ b/.claude/memory/learnings.md
@@ -29,3 +29,10 @@ enable+start `gnome-remote-desktop.service`. Auth = 2 layers: shared gate creds
 Listening socket + TLS + enable NOT enough alone. TPM warn `Init TPM credentials failed ... using
 GKeyFile as fallback` = harmless on TPM-less host (creds → keyfile). Connect: client → ip:3389,
 accept self-signed cert, gate creds, then GDM user. Supersedes LRN-003 for Wayland GNOME.
+
+## LRN-005 — df --output=pcent is GNU-only → keep /etc/profile.d disk scripts Linux-gated
+2026-06-24. `df --output=pcent` (and `/etc/profile.d` itself) are GNU coreutils / Debian conventions,
+absent on macOS BSD df. Any install step deploying such a snippet system-wide must sit inside the
+`command -v apt-get` (Linux) block, never the OS-agnostic path. Deploy idempotently with
+`sudo install -D -m 0644 src /etc/profile.d/x.sh` (-D makes the dir, overwrite = re-runnable). Caveat:
+`/etc/profile.d/*.sh` runs for LOGIN shells only — non-login terminals need `/etc/bash.bashrc` instead.
diff --git a/CLAUDE.md b/CLAUDE.md
index c8506a4..41df39b 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -22,6 +22,7 @@ vim/autoload/         pathogen loader (committed)
 vim/colors/           molokai colorscheme (committed)
 bash/bashrc-{linux,osx}          OS-detected bashrc
 bin/{dt,dtach-router,claude-provider}   CLI scripts deployed to ~/.local/bin
+etc/profile.d/disk-usage-warning.sh     login-time low-disk warning → /etc/profile.d (Linux only)
 .claude/{tasks,memory,audits}/   Claude working state
 ```
 
diff --git a/README.md b/README.md
index d3970b9..951424a 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,7 @@ curl -fsSL https://git.bchanot.fr/bchanot/config/raw/branch/master/remote-instal
 | `bin/dt`             | dtach session manager for claude-in-dtach sessions.            |
 | `bin/dtach-router`   | SSH-login dashboard to resume dtach sessions (sourced from bashrc). |
 | `bin/claude-provider`| Switch Claude Code between Anthropic and OpenRouter.           |
+| `etc/profile.d/disk-usage-warning.sh` | Login-time warning (bold red) when `/` or `/home` cross 85% usage. Deployed to `/etc/profile.d/` on Linux. |
 
 ## Install
 
@@ -57,6 +58,7 @@ What it does:
 6. Picks the bashrc by OS: macOS → `bashrc-osx` (falls back to `bashrc-linux` if missing), everything else → `bashrc-linux`. Copies it to `~/.bashrc`.
 7. Installs Python CLIs via `pipx` (`PyMuPDF` → `pymupdf`, `Markdown` → `markdown_py`) — skipped if `pipx` is absent.
 8. Copies the `bin/` scripts (`dt`, `dtach-router`, `claude-provider`) into `~/.local/bin`.
+9. On Linux, installs `etc/profile.d/disk-usage-warning.sh` to `/etc/profile.d/` (needs `sudo`) so each login warns when `/` or `/home` cross 85% usage.
 
 ### Packages installed (apt)
 
diff --git a/etc/profile.d/disk-usage-warning.sh b/etc/profile.d/disk-usage-warning.sh
new file mode 100644
index 0000000..fc00efa
--- /dev/null
+++ b/etc/profile.d/disk-usage-warning.sh
@@ -0,0 +1,19 @@
+#!/bin/sh
+# disk-usage-warning.sh — login-time low-disk warning.
+# Deployed to /etc/profile.d/ by install.sh, so every login shell sources it.
+# Warns in bold red when / or /home crosses THRESHOLD% usage.
+THRESHOLD=85
+
+check_disk() {
+    mount_point="$1"
+    usage=$(df "$mount_point" --output=pcent 2>/dev/null | tail -1 | tr -dc '0-9')
+    [ -z "$usage" ] && return
+    if [ "$usage" -ge "$THRESHOLD" ]; then
+        printf '\033[1;31m'   # rouge gras
+        printf '⚠  WARNING: %s à %s%% (seuil %s%%)\n' "$mount_point" "$usage" "$THRESHOLD"
+        printf '\033[0m'
+    fi
+}
+
+check_disk /home
+check_disk /
diff --git a/install.sh b/install.sh
index ca444d8..eade4c8 100755
--- a/install.sh
+++ b/install.sh
@@ -102,6 +102,17 @@ setup_remote_desktop() {
 	sudo systemctl restart gnome-remote-desktop.service
 }
 
+# Disk-usage login warning: a profile.d snippet that warns (bold red) at login when
+# / or /home cross the usage threshold. Deployed system-wide so every login shell
+# sources it. /etc/profile.d is a Debian/Ubuntu convention and df --output=pcent is
+# GNU-only, so this is Linux-only (called from the apt-get block). Idempotent: install
+# overwrites in place and -D creates the dir if missing.
+install_disk_warning() {
+	echo "Installing disk-usage login warning to /etc/profile.d"
+	sudo install -D -m 0644 "$SCRIPT_DIR/etc/profile.d/disk-usage-warning.sh" \
+		/etc/profile.d/disk-usage-warning.sh
+}
+
 # System packages: Debian/Ubuntu only. Skipped where apt-get is absent (e.g. macOS).
 if command -v apt-get >/dev/null 2>&1; then
 	sudo apt-get update
@@ -127,6 +138,9 @@ if command -v apt-get >/dev/null 2>&1; then
 
 	# Remote desktop (gnome-remote-desktop — see the function header for why not xrdp).
 	setup_remote_desktop
+
+	# Low-disk login warning (system-wide profile.d snippet).
+	install_disk_warning
 else
 	echo "apt-get not found — skipping system packages (install vim/git manually)."
 fi