diff --git a/CLAUDE.md b/CLAUDE.md
index 2153ef2..1b0550a 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -151,7 +151,7 @@ collapse and the existing grouping stands.
 
 `.env.example` follows its compose file's order. The names differ — one
 `PASSWORD` can feed several container variables, and `SERVICE_HOSTNAME` feeds
-`hostname:` — so each entry sits where the first compose entry that reads it sits.
+`hostname:` and `HOST` — so each entry sits where the first compose entry that reads it sits.
 Reordering a compose file means reordering the `.env.example` with it.
 
 ## Deployment target
diff --git a/code-server-lsio/.env.example b/code-server-lsio/.env.example
index 338184d..6738d00 100644
--- a/code-server-lsio/.env.example
+++ b/code-server-lsio/.env.example
@@ -2,7 +2,7 @@
 #
 #   cp .env.example .env
 
-# Container hostname.
+# Container hostname, also passed in as HOST -- the name zsh's prompt shows.
 SERVICE_HOSTNAME=code-server-lsio
 
 # Web UI login password. Required.
diff --git a/code-server-lsio/README.md b/code-server-lsio/README.md
index 8ed0930..564bad9 100644
--- a/code-server-lsio/README.md
+++ b/code-server-lsio/README.md
@@ -32,7 +32,7 @@ separate rootless daemon.
 
 | Variable | Purpose |
 | --- | --- |
-| `SERVICE_HOSTNAME` | Container hostname. |
+| `SERVICE_HOSTNAME` | Container hostname, and the name the shell prompt shows. |
 | `PASSWORD` | Web UI login, also the in-container sudo password. Required. |
 | `GIT_NAME` / `GIT_EMAIL` | Git author and committer identity |
 | `PWA_APPNAME` | Optional. Name of the installed web app; defaults to `code-server`. |
@@ -43,6 +43,14 @@ The compose file refuses to start when `PASSWORD` is unset or blank. The image
 itself would start anyway and serve code-server with no authentication, on a
 container that holds the Docker socket.
 
+`SERVICE_HOSTNAME` is used twice: as the container's `hostname:` and as the
+`HOST` variable inside it. Coolify injects `HOST=0.0.0.0` into every compose
+app, and zsh seeds `$HOST` and the `%m`/`%M` prompt escapes from that variable
+rather than calling `gethostname()` — so the prompt reads `0`, the first
+dot-separated field of `0.0.0.0`. code-server itself never reads `HOST` — it
+binds `[::]:8443` — so overriding it only affects the prompt. bash is
+unaffected; its `\h` uses the real hostname.
+
 `PUID`/`PGID` are pinned to `1000` in `compose.yml`; the `Dockerfile` depends
 on that (see [Storage](#storage)).
 
diff --git a/code-server-lsio/compose.yml b/code-server-lsio/compose.yml
index 401d15d..d6a9279 100644
--- a/code-server-lsio/compose.yml
+++ b/code-server-lsio/compose.yml
@@ -17,6 +17,7 @@ services:
       - GIT_AUTHOR_EMAIL=${GIT_EMAIL}
       - GIT_COMMITTER_NAME=${GIT_NAME}
       - GIT_COMMITTER_EMAIL=${GIT_EMAIL}
+      - HOST=${SERVICE_HOSTNAME}
       # - PWA_APPNAME=${PWA_APPNAME:-code-server}
     volumes:
       - 'code-server-config:/config'
diff --git a/code-server/.env.example b/code-server/.env.example
index 2740a59..5139180 100644
--- a/code-server/.env.example
+++ b/code-server/.env.example
@@ -2,7 +2,7 @@
 #
 #   cp .env.example .env
 
-# Container hostname.
+# Container hostname, also passed in as HOST -- the name zsh's prompt shows.
 SERVICE_HOSTNAME=code-server
 
 # Web UI login password. Required.
diff --git a/code-server/README.md b/code-server/README.md
index f7c1ebd..651a262 100644
--- a/code-server/README.md
+++ b/code-server/README.md
@@ -149,7 +149,7 @@ sdk install java
 | --- | --- |
 | `PASSWORD` | Web UI login. Required. |
 | `GIT_NAME` / `GIT_EMAIL` | Git author and committer identity |
-| `SERVICE_HOSTNAME` | Container hostname |
+| `SERVICE_HOSTNAME` | Container hostname, and the name the shell prompt shows (also passed as `HOST`) |
 | `CODE_SERVER_APP_NAME` | Optional. Name in the title bar and welcome page; defaults to `code-server`. |
 
 Generate a password with `openssl rand -base64 24`.
@@ -161,6 +161,13 @@ can only read from inside the container.
 The `coder` user has passwordless `sudo`, as the image sets it up. Anyone who
 can log in to the editor is root in the container.
 
+`SERVICE_HOSTNAME` is used twice: as the container's `hostname:` and as the
+`HOST` variable inside it. Coolify injects `HOST=0.0.0.0` into every compose
+app, and zsh seeds `$HOST` and the `%m`/`%M` prompt escapes from that variable
+rather than calling `gethostname()`, so a zsh prompt reads `0`. code-server
+itself never reads `HOST`; it binds through `--bind-addr`. bash is unaffected;
+its `\h` uses the real hostname.
+
 ## Docker access
 
 The host's Docker socket is bind-mounted at `/var/run/docker.sock`. The image
diff --git a/code-server/compose.yml b/code-server/compose.yml
index 962d6a7..83ee647 100644
--- a/code-server/compose.yml
+++ b/code-server/compose.yml
@@ -12,6 +12,7 @@ services:
       - GIT_AUTHOR_EMAIL=${GIT_EMAIL}
       - GIT_COMMITTER_NAME=${GIT_NAME}
       - GIT_COMMITTER_EMAIL=${GIT_EMAIL}
+      - HOST=${SERVICE_HOSTNAME}
       # - CODE_SERVER_APP_NAME=${CODE_SERVER_APP_NAME:-code-server}
     volumes:
       - 'code-server-home:/home/coder'
diff --git a/paseo/.env.example b/paseo/.env.example
index 08209d5..dec5552 100644
--- a/paseo/.env.example
+++ b/paseo/.env.example
@@ -2,7 +2,8 @@
 #
 #   cp .env.example .env
 
-# Container hostname, shown as the host label in the web UI.
+# Container hostname, shown as the host label in the web UI. Also passed in as
+# HOST -- the name zsh's prompt shows.
 SERVICE_HOSTNAME=paseo
 
 # Password for the daemon API and web UI. Also the paseo user's login password,
diff --git a/paseo/README.md b/paseo/README.md
index 079099b..87f38da 100644
--- a/paseo/README.md
+++ b/paseo/README.md
@@ -35,7 +35,7 @@ your own machine.
 | `PASEO_HOSTNAMES` | Domains allowed to reach the daemon, comma-separated. Your domain must be listed. |
 | `PASEO_TRUSTED_PROXIES` | Set to `uniquelocal`, or the UI loads but never connects. |
 | `AGENTS` | Agent CLIs to install on start if missing, space- or comma-separated. Empty installs none. See [Agents](#agents). |
-| `SERVICE_HOSTNAME` | Container hostname, shown as the host label in the UI. Without it the label is a random container ID. |
+| `SERVICE_HOSTNAME` | Container hostname, shown as the host label in the UI and in the shell prompt. Without it the label is a random container ID. |
 | `GIT_NAME` / `GIT_EMAIL` | Git author and committer identity for agents and terminals. |
 
 `PASEO_TRUSTED_PROXIES` matches the proxy's *source IP*, so hostnames are
@@ -46,8 +46,14 @@ the browser blocks that as mixed content. `uniquelocal` covers the private
 ranges Docker uses. An exact CIDR works too, but Coolify assigns a fresh subnet
 per project.
 
-`SERVICE_HOSTNAME` sets the container's `hostname:`, which is where the daemon
-takes its host label from.
+`SERVICE_HOSTNAME` is used twice: as the container's `hostname:`, which is
+where the daemon takes its host label from, and as the `HOST` variable inside
+it. Coolify injects `HOST=0.0.0.0` into every compose app, and zsh seeds `$HOST`
+and the `%m`/`%M` prompt escapes from that variable rather than calling
+`gethostname()` — so the prompt would read `0`, the first dot-separated field
+of `0.0.0.0`. Paseo itself never reads `HOST` — it binds `PASEO_LISTEN` — so
+overriding it only affects the prompt. bash is unaffected; its `\h` uses the
+real hostname.
 
 `SHELL=/bin/zsh` and `TZ=Asia/Ho_Chi_Minh` are written into `compose.yml`
 directly rather than read from `.env`, which is why neither is in the table.
diff --git a/paseo/compose.yml b/paseo/compose.yml
index e432a8c..84543e7 100644
--- a/paseo/compose.yml
+++ b/paseo/compose.yml
@@ -14,6 +14,7 @@ services:
       - GIT_AUTHOR_EMAIL=${GIT_EMAIL}
       - GIT_COMMITTER_NAME=${GIT_NAME}
       - GIT_COMMITTER_EMAIL=${GIT_EMAIL}
+      - HOST=${SERVICE_HOSTNAME}
     volumes:
       - 'paseo-home:/home/paseo'
       - 'paseo-workspace:/workspace'