diff --git a/.env.example b/.env.example
index 5164854..9eeaf42 100644
--- a/.env.example
+++ b/.env.example
@@ -162,7 +162,9 @@ PIPELINE_VERBATIM_MAX_CHARS=200000
 # reach the bot's own files or another server's.
 WORKSPACE_ENABLED=true
 # Base directory the per-server workspaces live under. Blank puts it at
-# .workspace/ beside the bot; set an absolute path to mount a volume there.
+# .workspace/ beside the bot. The Docker image sets this to /data/workspace,
+# so a volume mounted at /data (a Railway volume, or `docker run -v`) keeps
+# the workspace across redeploys. Set any absolute path to override.
 WORKSPACE_ROOT=
 # Caps: the largest single file, the whole workspace, and the file count.
 WORKSPACE_MAX_FILE_KB=64
diff --git a/Dockerfile b/Dockerfile
index 8684fea..97ab2f8 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -42,4 +42,13 @@ ENV PLUGIN_HTTP_ENABLED=true \
     PLUGIN_HTTP_MAX_REDIRECTS=3 \
     PLUGIN_HTTP_ALLOW_PRIVATE=false
 
+# Persistent storage. The agent file workspace lives under /data so it
+# survives a redeploy: attach a Railway volume (or `docker run -v`) with the
+# mount path /data and everything the files.* and shell.run tools write
+# persists. With nothing mounted, /data is an ordinary directory and the
+# workspace is ephemeral, exactly as before. An --env-file at run time still
+# overrides WORKSPACE_ROOT.
+RUN mkdir -p /data/workspace
+ENV WORKSPACE_ROOT=/data/workspace
+
 CMD ["python", "main.py"]
diff --git a/README.md b/README.md
index 69e0e18..f9c043a 100644
--- a/README.md
+++ b/README.md
@@ -102,10 +102,16 @@ boot -- it is idempotent.
 
 ```sh
 docker build -t archimedes .
-docker run --env-file .env archimedes
+docker run --env-file .env -v archimedes-data:/data archimedes
 ```
 
-A `railway.toml` is included for one-click Railway deploys.
+The agent file workspace lives under `/data` (`WORKSPACE_ROOT` is set to
+`/data/workspace` in the image), so mounting a volume there keeps it across
+restarts; without `-v` the workspace is ephemeral.
+
+A `railway.toml` is included for one-click Railway deploys. On Railway,
+attach a volume to the service with the mount path `/data` to get the same
+persistence.
 
 ## Configuration
 
diff --git a/cogs/chat.py b/cogs/chat.py
index ea2691a..f6d46d6 100644
--- a/cogs/chat.py
+++ b/cogs/chat.py
@@ -416,7 +416,7 @@ async def _stream_turn(
 
         async def _approver(name: str, args: dict) -> bool:
             return await self._collect_tool_approval(
-                channel_id, user_id, name, args)
+                placeholder.channel, user_id, name, args)
 
         tool_ctx.approver = _approver
         renderer = StreamRenderer(placeholder)
@@ -454,18 +454,19 @@ async def _approver(name: str, args: dict) -> bool:
         return final_text or None
 
     async def _collect_tool_approval(
-        self, channel_id: int, user_id: int, name: str, args: dict,
+        self, channel, user_id: int, name: str, args: dict,
     ) -> bool:
         """Post an Approve / Reject prompt for one gated tool call.
 
-        Returns the human decision. A send failure or an unanswered prompt
-        counts as a refusal -- a gated tool is never run without an explicit
-        yes. The prompt message is edited in place with the outcome, so the
-        channel keeps a record of who cleared what.
+        ``channel`` is the channel the turn is replying in -- a guild channel,
+        a thread or a DM alike -- taken straight from the placeholder message,
+        so the prompt always lands where the user is looking and never depends
+        on a channel-cache lookup that misses for DMs. Returns the human
+        decision; a send failure or an unanswered prompt counts as a refusal,
+        so a gated tool is never run without an explicit yes. The prompt is
+        edited in place with the outcome, so the channel keeps a record of who
+        cleared what.
         """
-        channel = self.bot.get_channel(channel_id)
-        if channel is None:
-            return False
         timeout = float(max(5, Config.AGENT_APPROVAL_TIMEOUT_S))
         decision: asyncio.Future[bool] = (
             asyncio.get_running_loop().create_future()
diff --git a/railway.toml b/railway.toml
index 8c54924..cdc9bc1 100644
--- a/railway.toml
+++ b/railway.toml
@@ -1,3 +1,9 @@
+# Persistent storage: attach a volume to this service in the Railway
+# dashboard with the mount path /data. The agent file workspace then lives on
+# it -- WORKSPACE_ROOT is set to /data/workspace in the Dockerfile -- and
+# survives every redeploy. Railway volumes are attached in the dashboard, not
+# declared in this file.
+
 [build]
 builder = "DOCKERFILE"
 dockerfilePath = "Dockerfile"