diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
index 709d08d..a965275 100644
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -205,19 +205,19 @@ Runs the FastAPI app and Nginx; serves the built PWA static files.
   starting point, managed by a systemd unit:
 
 ```ini
-# /etc/systemd/system/chatapp.service
+# /etc/systemd/system/ds-chat.service
 [Unit]
 Description=Chat service app server
 After=network.target
 
 [Service]
-User=chatapp
-WorkingDirectory=/srv/chatapp
-EnvironmentFile=/etc/chatapp/env
-ExecStart=/srv/chatapp/venv/bin/gunicorn app.main:app \
+User=ds-chat
+WorkingDirectory=/srv/ds-chat
+EnvironmentFile=/etc/ds-chat/env
+ExecStart=/srv/ds-chat/venv/bin/gunicorn app.main:app \
   -k uvicorn.workers.UvicornWorker \
   --workers 4 \
-  --bind unix:/run/chatapp/chatapp.sock
+  --bind unix:/run/ds-chat/ds-chat.sock
 Restart=on-failure
 
 [Install]
@@ -233,16 +233,16 @@ server {
     listen 443 ssl;
     server_name chat.example.com;
 
-    root /srv/chatapp/frontend/dist;
+    root /srv/ds-chat/frontend/dist;
     try_files $uri /index.html;
 
     location /api/ {
-        proxy_pass http://unix:/run/chatapp/chatapp.sock;
+        proxy_pass http://unix:/run/ds-chat/ds-chat.sock;
         proxy_set_header Host $host;
     }
 
     location /ws/ {
-        proxy_pass http://unix:/run/chatapp/chatapp.sock;
+        proxy_pass http://unix:/run/ds-chat/ds-chat.sock;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
         proxy_set_header Connection "upgrade";
@@ -252,12 +252,12 @@ server {
 ```
 
 - Secrets (database URL pointing at the data server's private IP, Redis URL,
-  VAPID keys, session secret) live in `/etc/chatapp/env`, loaded via
+  VAPID keys, session secret) live in `/etc/ds-chat/env`, loaded via
   `EnvironmentFile=`, never committed to the repository.
 - Deploy process: `git pull`, install/update dependencies, `alembic upgrade
-  head`, build the frontend, `systemctl restart chatapp`, `nginx -s reload` if
+  head`, build the frontend, `systemctl restart ds-chat`, `nginx -s reload` if
   the Nginx config changed.
-- Logs: `journalctl -u chatapp`, rotated by systemd/journald defaults; add
+- Logs: `journalctl -u ds-chat`, rotated by systemd/journald defaults; add
   `logrotate` if the app also writes its own log files.
 
 ## 10. Security considerations
diff --git a/DEPLOYMENT.md b/DEPLOYMENT.md
index 3b37d5c..3a27d6e 100644
--- a/DEPLOYMENT.md
+++ b/DEPLOYMENT.md
@@ -1,4 +1,4 @@
-# Deploying KeepItTalking
+# Deploying DS Chat
 
 Two Debian 13 servers, no containers, matching [ARCHITECTURE.md §9](ARCHITECTURE.md#9-deployment-architecture--two-linux-servers-no-docker):
 
@@ -49,8 +49,8 @@ sudo apt install -y postgresql redis-server
 **PostgreSQL** — create the role and database:
 
 ```bash
-sudo -u postgres psql -c "CREATE ROLE chatapp WITH LOGIN PASSWORD '<DB_PASSWORD>';"
-sudo -u postgres psql -c "CREATE DATABASE chatapp OWNER chatapp;"
+sudo -u postgres psql -c "CREATE ROLE ds_chat WITH LOGIN PASSWORD '<DB_PASSWORD>';"
+sudo -u postgres psql -c "CREATE DATABASE ds_chat OWNER ds_chat;"
 ```
 
 Bind it to the private interface only (find the exact config path with
@@ -67,7 +67,7 @@ enough (a single `/32`) that it won't collide with Debian's default
 `127.0.0.1`/`::1`-only entries, so appending is fine:
 
 ```bash
-echo "host    chatapp    chatapp    <APP_SERVER_PRIVATE_IP>/32    scram-sha-256" \
+echo "host    ds_chat    ds_chat    <APP_SERVER_PRIVATE_IP>/32    scram-sha-256" \
   | sudo tee -a /etc/postgresql/17/main/pg_hba.conf
 sudo systemctl restart postgresql
 ```
@@ -95,35 +95,35 @@ sudo ufw enable
 install steps (copy it to `/usr/local/bin/`, cron entry). Off-box shipping
 is left as a placeholder in that script — see §8 below.
 
-## 3. App server: Python, Node.js, the `chatapp` user, and the app itself
+## 3. App server: Python, Node.js, the `ds-chat` user, and the app itself
 
 ```bash
 sudo apt update
 sudo apt install -y python3 python3-venv nodejs npm git
 ```
 
-### 3a. The `chatapp` system user and directory
+### 3a. The `ds-chat` system user and directory
 
 ```bash
-sudo useradd --system --shell /usr/sbin/nologin --home-dir /srv/chatapp --create-home chatapp
-sudo chown chatapp:chatapp /srv/chatapp
-sudo -u chatapp mkdir -p /srv/chatapp/uploads
+sudo useradd --system --shell /usr/sbin/nologin --home-dir /srv/ds-chat --create-home ds-chat
+sudo chown ds-chat:ds-chat /srv/ds-chat
+sudo -u ds-chat mkdir -p /srv/ds-chat/uploads
 ```
 
 ### 3b. Clone the repo (deploy key, not a personal token)
 
 ```bash
-sudo -u chatapp mkdir -p /srv/chatapp/.ssh
-sudo -u chatapp ssh-keygen -t ed25519 -f /srv/chatapp/.ssh/id_ed25519 -N ""
-sudo cat /srv/chatapp/.ssh/id_ed25519.pub
+sudo -u ds-chat mkdir -p /srv/ds-chat/.ssh
+sudo -u ds-chat ssh-keygen -t ed25519 -f /srv/ds-chat/.ssh/id_ed25519 -N ""
+sudo cat /srv/ds-chat/.ssh/id_ed25519.pub
 ```
 
 Add that public key as a **read-only deploy key** on the Gitea repo
 (Settings → Deploy Keys), then:
 
 ```bash
-sudo -u chatapp ssh-keyscan git.darksingularity.org >> /srv/chatapp/.ssh/known_hosts
-sudo -u chatapp git clone git@git.darksingularity.org:DarkSingularity/KeepItTalking.git /srv/chatapp
+sudo -u ds-chat ssh-keyscan git.darksingularity.org >> /srv/ds-chat/.ssh/known_hosts
+sudo -u ds-chat git clone git@git.darksingularity.org:DarkSingularity/ds-chat.git /srv/ds-chat
 ```
 
 (If your Gitea's SSH is on a non-default port, adjust the clone URL and
@@ -132,16 +132,16 @@ sudo -u chatapp git clone git@git.darksingularity.org:DarkSingularity/KeepItTalk
 ### 3c. Backend: venv, env file, migrations, first admin
 
 ```bash
-sudo -u chatapp python3 -m venv /srv/chatapp/backend/.venv
-sudo -u chatapp /srv/chatapp/backend/.venv/bin/pip install -e /srv/chatapp/backend
+sudo -u ds-chat python3 -m venv /srv/ds-chat/backend/.venv
+sudo -u ds-chat /srv/ds-chat/backend/.venv/bin/pip install -e /srv/ds-chat/backend
 ```
 
 ```bash
-sudo mkdir -p /etc/chatapp
-sudo cp /srv/chatapp/deploy/chatapp.env.example /etc/chatapp/env
-sudo chown root:chatapp /etc/chatapp/env
-sudo chmod 0640 /etc/chatapp/env
-sudo -e /etc/chatapp/env   # fill in DATABASE_URL, REDIS_URL, SESSION_SECRET (see below)
+sudo mkdir -p /etc/ds-chat
+sudo cp /srv/ds-chat/deploy/ds-chat.env.example /etc/ds-chat/env
+sudo chown root:ds-chat /etc/ds-chat/env
+sudo chmod 0640 /etc/ds-chat/env
+sudo -e /etc/ds-chat/env   # fill in DATABASE_URL, REDIS_URL, SESSION_SECRET (see below)
 ```
 
 Generate `SESSION_SECRET`:
@@ -150,23 +150,23 @@ Generate `SESSION_SECRET`:
 python3 -c "import secrets; print(secrets.token_urlsafe(32))"
 ```
 
-Run migrations and create the first admin account (as `chatapp`, with the
+Run migrations and create the first admin account (as `ds-chat`, with the
 env file sourced so `DATABASE_URL` is set):
 
 ```bash
-sudo -u chatapp bash -c 'set -a; source /etc/chatapp/env; set +a; \
-  cd /srv/chatapp/backend && .venv/bin/alembic upgrade head'
+sudo -u ds-chat bash -c 'set -a; source /etc/ds-chat/env; set +a; \
+  cd /srv/ds-chat/backend && .venv/bin/alembic upgrade head'
 
-sudo -u chatapp bash -c 'set -a; source /etc/chatapp/env; set +a; \
-  cd /srv/chatapp/backend && .venv/bin/python -m app.cli create-user <ADMIN_USERNAME> <ADMIN_EMAIL> "<ADMIN_PASSWORD>" --admin'
+sudo -u ds-chat bash -c 'set -a; source /etc/ds-chat/env; set +a; \
+  cd /srv/ds-chat/backend && .venv/bin/python -m app.cli create-user <ADMIN_USERNAME> <ADMIN_EMAIL> "<ADMIN_PASSWORD>" --admin'
 ```
 
 Optional: push notifications. Skipped silently if `VAPID_PUBLIC_KEY`/
-`VAPID_PRIVATE_KEY` are left unset in `/etc/chatapp/env`. To enable:
+`VAPID_PRIVATE_KEY` are left unset in `/etc/ds-chat/env`. To enable:
 
 ```bash
-sudo -u chatapp /srv/chatapp/backend/.venv/bin/python -m app.cli generate-vapid-keys
-# paste the three printed lines into /etc/chatapp/env
+sudo -u ds-chat /srv/ds-chat/backend/.venv/bin/python -m app.cli generate-vapid-keys
+# paste the three printed lines into /etc/ds-chat/env
 ```
 
 Optional: outgoing email (admin-invited signups, room membership notifications).
@@ -182,16 +182,16 @@ admin sets it up.
 Manager forward the whole domain to one port with no custom path routing.
 
 ```bash
-sudo -u chatapp bash -c 'cd /srv/chatapp/frontend && npm ci && npm run build'
+sudo -u ds-chat bash -c 'cd /srv/ds-chat/frontend && npm ci && npm run build'
 ```
 
 ### 3e. systemd unit
 
 ```bash
-sudo cp /srv/chatapp/deploy/systemd/chatapp.service /etc/systemd/system/
+sudo cp /srv/ds-chat/deploy/systemd/ds-chat.service /etc/systemd/system/
 sudo systemctl daemon-reload
-sudo systemctl enable --now chatapp
-sudo systemctl status chatapp --no-pager
+sudo systemctl enable --now ds-chat
+sudo systemctl status ds-chat --no-pager
 ```
 
 Confirm it's actually up before continuing:
@@ -200,13 +200,13 @@ Confirm it's actually up before continuing:
 curl -s http://127.0.0.1:8000/api/health   # expect {"status":"ok"}
 ```
 
-### 3f. Let `chatapp` restart its own service (needed for `deploy/upgrade.sh`)
+### 3f. Let `ds-chat` restart its own service (needed for `deploy/upgrade.sh`)
 
 ```bash
-echo 'chatapp ALL=(root) NOPASSWD: /usr/bin/systemctl restart chatapp, /usr/bin/systemctl status chatapp' \
-  | sudo tee /etc/sudoers.d/chatapp
-sudo chmod 0440 /etc/sudoers.d/chatapp
-sudo visudo -cf /etc/sudoers.d/chatapp   # validates syntax before it's live
+echo 'ds-chat ALL=(root) NOPASSWD: /usr/bin/systemctl restart ds-chat, /usr/bin/systemctl status ds-chat' \
+  | sudo tee /etc/sudoers.d/ds-chat
+sudo chmod 0440 /etc/sudoers.d/ds-chat
+sudo visudo -cf /etc/sudoers.d/ds-chat   # validates syntax before it's live
 ```
 
 ### 3g. Firewall
@@ -222,7 +222,7 @@ sudo ufw enable
 
 If NPM reaches this box over the same private network the data server
 uses, bind gunicorn to that private IP instead of `0.0.0.0` in
-`deploy/systemd/chatapp.service` for defense in depth on top of the
+`deploy/systemd/ds-chat.service` for defense in depth on top of the
 firewall rule (edit `--bind`, then `daemon-reload` + `restart`).
 
 ## 4. Configuring Nginx Proxy Manager
@@ -251,17 +251,17 @@ This is config in NPM's own UI/database, not a file this repo ships:
 - Open `https://chat.example.com` in a browser, log in with the admin
   account from §3c, create a room, send a message, confirm it appears
   live (WebSocket working).
-- `sudo journalctl -u chatapp -f` on the app server while doing the above —
+- `sudo journalctl -u ds-chat -f` on the app server while doing the above —
   should show request logs, no tracebacks.
 
 ## 6. Upgrades
 
 ```bash
-sudo -u chatapp /srv/chatapp/deploy/upgrade.sh
+sudo -u ds-chat /srv/ds-chat/deploy/upgrade.sh
 ```
 
 Pulls latest `main`, reinstalls backend deps, runs `alembic upgrade head`,
-rebuilds the frontend, restarts `chatapp`, and curls `/api/health` to
+rebuilds the frontend, restarts `ds-chat`, and curls `/api/health` to
 confirm it came back up. Fails loudly (`set -euo pipefail`) and stops
 before restarting anything if an earlier step — most importantly a failed
 migration — errors out, so a bad deploy doesn't take down the previously
@@ -281,30 +281,30 @@ in practice, downgrades written and tested by hand if one is ever needed).
 ## 7. Backups
 
 `deploy/backup-postgres.sh` (installed in §2) runs nightly via cron,
-producing a gzipped `pg_dump` in `/var/backups/chatapp/` with 14-day local
+producing a gzipped `pg_dump` in `/var/backups/ds-chat/` with 14-day local
 rotation. Off-box shipping is a placeholder in that script (commented-out
 rsync/S3 examples) — decide where those need to go and fill it in.
 
 That script covers Postgres only. Uploaded chat images live on the **app**
-server's disk (`/srv/chatapp/uploads`, created in §3a) — a separate machine
+server's disk (`/srv/ds-chat/uploads`, created in §3a) — a separate machine
 from the data server this script runs on — and currently have no backup
 mechanism at all. Whatever off-box destination you pick above, include
-`/srv/chatapp/uploads` in it too (e.g. a second `rsync` line run from the
+`/srv/ds-chat/uploads` in it too (e.g. a second `rsync` line run from the
 app server).
 
 **Test a restore** (against a scratch database, never directly onto
-`chatapp`):
+`ds_chat`):
 
 ```bash
-sudo -u postgres createdb chatapp_restore_test
-gunzip -c /var/backups/chatapp/chatapp-<TIMESTAMP>.sql.gz | sudo -u postgres psql chatapp_restore_test
-sudo -u postgres dropdb chatapp_restore_test
+sudo -u postgres createdb ds_chat_restore_test
+gunzip -c /var/backups/ds-chat/ds-chat-<TIMESTAMP>.sql.gz | sudo -u postgres psql ds_chat_restore_test
+sudo -u postgres dropdb ds_chat_restore_test
 ```
 
 ## 8. Troubleshooting
 
-- **`chatapp` service won't start**: `sudo journalctl -u chatapp -n 50`.
-  Common causes: `/etc/chatapp/env` missing/malformed (gunicorn workers
+- **`ds-chat` service won't start**: `sudo journalctl -u ds-chat -n 50`.
+  Common causes: `/etc/ds-chat/env` missing/malformed (gunicorn workers
   crash-loop on `pydantic-settings` validation errors), or Postgres/Redis
   unreachable (check the data-server firewall rules in §2 actually match
   the app server's real private IP).
@@ -313,7 +313,7 @@ sudo -u postgres dropdb chatapp_restore_test
   (isolates "app is down" from "NPM can't reach it") — then check §3g's
   `ufw` rule matches NPM's actual source IP.
 - **Migration fails mid-`upgrade.sh`**: the script stops before restarting
-  `chatapp`, so the previous (still-migrated-to-its-old-schema) code keeps
+  `ds-chat`, so the previous (still-migrated-to-its-old-schema) code keeps
   running. Fix the migration, re-run the script.
 - **Chat works but disconnects after ~a minute of inactivity, then
   reconnects**: expected under the current design (§4's NPM timeout note) —
@@ -334,7 +334,7 @@ scope decisions" for the full detail on each):
   re-validated per delivery (DNS-rebinding gap).
 - Backup off-box shipping is a placeholder — decide a destination and fill
   in `deploy/backup-postgres.sh`.
-- Uploaded chat images (`/srv/chatapp/uploads` on the app server) have no
+- Uploaded chat images (`/srv/ds-chat/uploads` on the app server) have no
   backup coverage at all yet, on-box or off — see §7.
 - Uploaded-but-never-sent images (a user attaches a file, then never hits
   Send) leak an orphaned file on disk — no cleanup job for this yet. Not a
diff --git a/README.md b/README.md
index 1f5721b..d2d762d 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# KeepItTalking
+# DS Chat
 
 A web-based team chat service (Mattermost-style, no threaded conversations),
 invite-only. See [ARCHITECTURE.md](ARCHITECTURE.md) for the full system design
@@ -25,8 +25,8 @@ prioritized.
 
 ```bash
 # 1. Postgres (see backend/README.md for details)
-docker run -d --name chatapp-postgres \
-  -e POSTGRES_USER=chatapp -e POSTGRES_PASSWORD=chatapp -e POSTGRES_DB=chatapp \
+docker run -d --name ds-chat-postgres \
+  -e POSTGRES_USER=ds_chat -e POSTGRES_PASSWORD=ds_chat -e POSTGRES_DB=ds_chat \
   -p 5432:5432 postgres:16-alpine
 
 # 2. Backend
diff --git a/backend/.env.example b/backend/.env.example
index 81ebd38..1809c40 100644
--- a/backend/.env.example
+++ b/backend/.env.example
@@ -1,4 +1,4 @@
-DATABASE_URL=postgresql+asyncpg://chatapp:chatapp@localhost:5432/chatapp
+DATABASE_URL=postgresql+asyncpg://ds_chat:ds_chat@localhost:5432/ds_chat
 SESSION_SECRET=change-me-to-a-long-random-string
 SESSION_HTTPS_ONLY=false
 REDIS_URL=redis://localhost:6379/0
diff --git a/backend/README.md b/backend/README.md
index 6b6dc61..062e661 100644
--- a/backend/README.md
+++ b/backend/README.md
@@ -1,4 +1,4 @@
-# KeepItTalking backend (Phase 1 + 2 + 4 + 5 + 6 + 7 + 8, image uploads, file attachments, admin-configurable upload size limits, emoji & reactions, user profiles, site invites & email, password reset)
+# DS Chat backend (Phase 1 + 2 + 4 + 5 + 6 + 7 + 8, image uploads, file attachments, admin-configurable upload size limits, emoji & reactions, user profiles, site invites & email, password reset)
 
 FastAPI + SQLAlchemy 2.0 (async) + PostgreSQL + Redis. Implements auth, room
 CRUD (open and private), room roles (owner/admin/member) and direct
@@ -24,15 +24,15 @@ Accounts are created by an operator on the app server — see step 4 below.
 Any local Postgres 14+ works. The quickest option is a container:
 
 ```bash
-docker run -d --name chatapp-postgres \
-  -e POSTGRES_USER=chatapp -e POSTGRES_PASSWORD=chatapp -e POSTGRES_DB=chatapp \
+docker run -d --name ds-chat-postgres \
+  -e POSTGRES_USER=ds_chat -e POSTGRES_PASSWORD=ds_chat -e POSTGRES_DB=ds_chat \
   -p 5432:5432 postgres:16-alpine
 ```
 
 Then create the test database (used by the test suite, kept separate from dev data):
 
 ```bash
-docker exec chatapp-postgres psql -U chatapp -d chatapp -c "CREATE DATABASE chatapp_test;"
+docker exec ds-chat-postgres psql -U ds_chat -d ds_chat -c "CREATE DATABASE ds_chat_test;"
 ```
 
 (Docker here is purely a local-dev convenience for standing up Postgres quickly —
@@ -44,7 +44,7 @@ Used for cross-instance WebSocket fan-out and presence (see the section
 below). Required — there's no in-memory fallback.
 
 ```bash
-docker run -d --name chatapp-redis -p 6379:6379 redis:7-alpine
+docker run -d --name ds-chat-redis -p 6379:6379 redis:7-alpine
 ```
 
 ### 3. Python environment
@@ -99,13 +99,13 @@ connected to the other, purely via Redis.
 
 ### 8. Run tests
 
-Tests run against a real Postgres database (`chatapp_test` by default — native
+Tests run against a real Postgres database (`ds_chat_test` by default — native
 `ENUM`/`UUID` types aren't faithfully reproduced by SQLite) and a real Redis
 (db 15 by default, kept separate from dev use of db 0), with each test
 wrapped in a transaction that's rolled back afterward:
 
 ```bash
-DATABASE_URL=postgresql+asyncpg://chatapp:chatapp@localhost:5432/chatapp_test .venv/bin/pytest
+DATABASE_URL=postgresql+asyncpg://ds_chat:ds_chat@localhost:5432/ds_chat_test .venv/bin/pytest
 ```
 
 ## Layout
@@ -247,7 +247,7 @@ call sites rather than duplicated).
 **Outgoing webhooks / event subscriptions** (`POST
 /api/rooms/{id}/event-subscriptions`, room-admin managed; room-scoped or
 global via `room_id=null`): fires an HMAC-SHA256-signed POST
-(`X-KeepItTalking-Signature: sha256=...`) on `message.created`/
+(`X-DS-Chat-Signature: sha256=...`) on `message.created`/
 `message.updated`, delivered via a backgrounded `asyncio.create_task`
 (`app/services/webhook_delivery.py`) — safe to background here, unlike the
 Phase 4 push lesson, since there's no DB session involved, just the
diff --git a/backend/alembic.ini b/backend/alembic.ini
index 7152cdd..d180567 100644
--- a/backend/alembic.ini
+++ b/backend/alembic.ini
@@ -86,7 +86,7 @@ path_separator = os
 # database URL.  This is consumed by the user-maintained env.py script only.
 # other means of configuring database URLs may be customized within the env.py
 # file.
-sqlalchemy.url = postgresql+asyncpg://chatapp:chatapp@localhost:5432/chatapp
+sqlalchemy.url = postgresql+asyncpg://chatapp:chatapp@localhost:5432/ds_chat
 
 
 [post_write_hooks]
diff --git a/backend/app/main.py b/backend/app/main.py
index 31f81e0..31522a9 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -18,8 +18,8 @@ from app.ws.connection_manager import ConnectionManager
 from app.ws.presence import Presence
 
 # backend/app/main.py -> backend/ -> repo root -- matches both the local
-# monorepo layout and the production layout (/srv/chatapp/backend,
-# /srv/chatapp/frontend/dist), which is the same relative shape.
+# monorepo layout and the production layout (/srv/ds-chat/backend,
+# /srv/ds-chat/frontend/dist), which is the same relative shape.
 FRONTEND_DIST = pathlib.Path(__file__).resolve().parent.parent.parent / "frontend" / "dist"
 
 
@@ -55,7 +55,7 @@ async def lifespan(app: FastAPI) -> AsyncIterator[None]:
 
 
 def create_app() -> FastAPI:
-    app = FastAPI(title="KeepItTalking", lifespan=lifespan)
+    app = FastAPI(title="DS Chat", lifespan=lifespan)
 
     app.add_middleware(
         SessionMiddleware,
diff --git a/backend/app/services/email_service.py b/backend/app/services/email_service.py
index d5963c8..ab77f42 100644
--- a/backend/app/services/email_service.py
+++ b/backend/app/services/email_service.py
@@ -58,6 +58,6 @@ async def send_test_email(db: AsyncSession, to_address: str) -> None:
     await _deliver(
         cfg,
         to_address,
-        "KeepItTalking test email",
-        "This is a test email from KeepItTalking to confirm your SMTP settings are working.",
+        "DS Chat test email",
+        "This is a test email from DS Chat to confirm your SMTP settings are working.",
     )
diff --git a/backend/app/services/password_service.py b/backend/app/services/password_service.py
index e976464..91608bd 100644
--- a/backend/app/services/password_service.py
+++ b/backend/app/services/password_service.py
@@ -44,7 +44,7 @@ async def request_password_reset(db: AsyncSession, email: str, base_url: str) ->
     await send_email(
         db,
         email,
-        "Reset your KeepItTalking password",
+        "Reset your DS Chat password",
         f"Someone requested a password reset for this account.\n\n"
         f"Reset it here:\n{reset_link}\n\n"
         f"This link expires in 15 minutes. If you didn't request this, "
diff --git a/backend/app/services/room_service.py b/backend/app/services/room_service.py
index 3719abb..5436b3f 100644
--- a/backend/app/services/room_service.py
+++ b/backend/app/services/room_service.py
@@ -140,7 +140,7 @@ async def add_member(
         db,
         target.email,
         f"You've been added to #{room.name}",
-        f"You've been added to the #{room.name} room on KeepItTalking.\n\n"
+        f"You've been added to the #{room.name} room on DS Chat.\n\n"
         f"Open the app: {base_url.rstrip('/')}",
     )
 
diff --git a/backend/app/services/site_invite_service.py b/backend/app/services/site_invite_service.py
index 03964ca..9b0262f 100644
--- a/backend/app/services/site_invite_service.py
+++ b/backend/app/services/site_invite_service.py
@@ -43,8 +43,8 @@ async def create_site_invite(
     await send_email(
         db,
         email,
-        "You're invited to join KeepItTalking",
-        f"You've been invited to join KeepItTalking by {actor.username}.\n\n"
+        "You're invited to join DS Chat",
+        f"You've been invited to join DS Chat by {actor.username}.\n\n"
         f"Set up your account here:\n{signup_link}\n\n"
         f"This link expires in 7 days.",
     )
diff --git a/backend/app/services/webhook_delivery.py b/backend/app/services/webhook_delivery.py
index 925e4d3..99acdc4 100644
--- a/backend/app/services/webhook_delivery.py
+++ b/backend/app/services/webhook_delivery.py
@@ -32,7 +32,7 @@ async def deliver_event(subscription: EventSubscription, event_type: str, payloa
                 content=body,
                 headers={
                     "Content-Type": "application/json",
-                    "X-KeepItTalking-Signature": f"sha256={signature}",
+                    "X-DS-Chat-Signature": f"sha256={signature}",
                 },
             )
     except httpx.HTTPError:
diff --git a/backend/app/storage.py b/backend/app/storage.py
index c0d176e..e85d217 100644
--- a/backend/app/storage.py
+++ b/backend/app/storage.py
@@ -6,7 +6,7 @@ from PIL import Image, UnidentifiedImageError
 
 # backend/app/storage.py -> backend/ -> repo root -- same
 # resolve-relative-to-file convention FRONTEND_DIST uses in app/main.py, so
-# this lands in the right place in both local dev and the /srv/chatapp
+# this lands in the right place in both local dev and the /srv/ds-chat
 # production layout with zero new config.
 UPLOADS_DIR = pathlib.Path(__file__).resolve().parent.parent.parent / "uploads"
 
diff --git a/backend/pyproject.toml b/backend/pyproject.toml
index d3b2be0..47c1019 100644
--- a/backend/pyproject.toml
+++ b/backend/pyproject.toml
@@ -1,7 +1,7 @@
 [project]
-name = "chatapp"
+name = "ds-chat"
 version = "0.1.0"
-description = "KeepItTalking chat service backend"
+description = "DS Chat backend service"
 requires-python = ">=3.11"
 dependencies = [
     "fastapi>=0.115",
@@ -25,7 +25,7 @@ dependencies = [
 ]
 
 [project.scripts]
-chatapp-create-user = "app.cli:main"
+ds-chat-create-user = "app.cli:main"
 
 [project.optional-dependencies]
 dev = [
diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
index a8a146b..54ab6f5 100644
--- a/backend/tests/conftest.py
+++ b/backend/tests/conftest.py
@@ -3,7 +3,7 @@ import os
 from pathlib import Path
 
 os.environ.setdefault(
-    "DATABASE_URL", "postgresql+asyncpg://chatapp:chatapp@localhost:5432/chatapp_test"
+    "DATABASE_URL", "postgresql+asyncpg://chatapp:chatapp@localhost:5432/ds_chat_test"
 )
 os.environ.setdefault("SESSION_SECRET", "test-secret")
 os.environ.setdefault("SESSION_HTTPS_ONLY", "false")
diff --git a/backend/tests/test_push.py b/backend/tests/test_push.py
index 8b7c79f..1c48ec7 100644
--- a/backend/tests/test_push.py
+++ b/backend/tests/test_push.py
@@ -31,7 +31,7 @@ async def test_subscribe_creates_row(client, db_session):
     resp = await client.post("/api/push/subscribe", json=payload)
     assert resp.status_code == 204
 
-    # The chatapp_test database is shared across the whole suite and the
+    # The ds_chat_test database is shared across the whole suite and the
     # ws_client-based tests below intentionally don't roll back (see
     # conftest.ws_client), so a unique endpoint keeps this test independent
     # of leftover rows from those instead of asserting on the total count.
diff --git a/backend/tests/test_webhooks.py b/backend/tests/test_webhooks.py
index 466eb8c..a487c96 100644
--- a/backend/tests/test_webhooks.py
+++ b/backend/tests/test_webhooks.py
@@ -158,7 +158,7 @@ async def test_outgoing_webhook_delivers_signed_payload(client, db_session, monk
     assert len(posts) == 1
     body = posts[0]["content"]
     expected_signature = hmac.new(secret.encode(), body, hashlib.sha256).hexdigest()
-    assert posts[0]["headers"]["X-KeepItTalking-Signature"] == f"sha256={expected_signature}"
+    assert posts[0]["headers"]["X-DS-Chat-Signature"] == f"sha256={expected_signature}"
     payload = json.loads(body)
     assert payload["event"] == "message.created"
     assert payload["data"]["content"] == "ping"
diff --git a/deploy/backup-postgres.sh b/deploy/backup-postgres.sh
index a4d6e09..4a794d0 100755
--- a/deploy/backup-postgres.sh
+++ b/deploy/backup-postgres.sh
@@ -1,27 +1,27 @@
 #!/usr/bin/env bash
-# Nightly Postgres backup for the KeepItTalking data server.
+# Nightly Postgres backup for the DS Chat data server.
 #
 # Install (as root, on the data server):
-#   sudo cp deploy/backup-postgres.sh /usr/local/bin/chatapp-backup-postgres.sh
-#   sudo chmod 0700 /usr/local/bin/chatapp-backup-postgres.sh
+#   sudo cp deploy/backup-postgres.sh /usr/local/bin/ds-chat-backup-postgres.sh
+#   sudo chmod 0700 /usr/local/bin/ds-chat-backup-postgres.sh
 #   sudo crontab -e
 #     # add:
-#     0 3 * * * /usr/local/bin/chatapp-backup-postgres.sh
+#     0 3 * * * /usr/local/bin/ds-chat-backup-postgres.sh
 #
 # See ../DEPLOYMENT.md for the full data-server setup this fits into.
 #
 # Covers Postgres only. Uploaded chat images live on the app server's disk
-# (/srv/chatapp/uploads, see app/storage.py), not here -- see DEPLOYMENT.md
+# (/srv/ds-chat/uploads, see app/storage.py), not here -- see DEPLOYMENT.md
 # §7 for that gap.
 
 set -euo pipefail
 
-DB_NAME="chatapp"
-DB_USER="chatapp"
-BACKUP_DIR="/var/backups/chatapp"
+DB_NAME="ds_chat"
+DB_USER="ds_chat"
+BACKUP_DIR="/var/backups/ds-chat"
 RETENTION_DAYS=14
 TIMESTAMP="$(date +%F-%H%M%S)"
-DEST="${BACKUP_DIR}/chatapp-${TIMESTAMP}.sql.gz"
+DEST="${BACKUP_DIR}/ds-chat-${TIMESTAMP}.sql.gz"
 
 mkdir -p "$BACKUP_DIR"
 
@@ -35,7 +35,7 @@ echo "Backed up ${DB_NAME} to ${DEST}"
 
 # Local rotation -- keep RETENTION_DAYS days on this box regardless of
 # whether off-box shipping (below) is configured yet.
-find "$BACKUP_DIR" -name 'chatapp-*.sql.gz' -mtime "+${RETENTION_DAYS}" -delete
+find "$BACKUP_DIR" -name 'ds-chat-*.sql.gz' -mtime "+${RETENTION_DAYS}" -delete
 
 # --- Off-box shipping -------------------------------------------------
 # Not configured yet -- destination wasn't decided as of this script being
@@ -44,9 +44,9 @@ find "$BACKUP_DIR" -name 'chatapp-*.sql.gz' -mtime "+${RETENTION_DAYS}" -delete
 #
 # rsync (to a second host reachable by the data server, e.g. over the same
 # private network / a WireGuard tunnel used for anything else):
-#   rsync -a "$DEST" backup-user@backup-host:/path/to/chatapp-backups/
+#   rsync -a "$DEST" backup-user@backup-host:/path/to/ds-chat-backups/
 #
 # S3-compatible object storage (needs `aws configure` or rclone set up
 # separately first):
-#   aws s3 cp "$DEST" s3://your-bucket/chatapp-backups/
-#   # or: rclone copy "$DEST" remote:chatapp-backups/
+#   aws s3 cp "$DEST" s3://your-bucket/ds-chat-backups/
+#   # or: rclone copy "$DEST" remote:ds-chat-backups/
diff --git a/deploy/chatapp.env.example b/deploy/ds-chat.env.example
similarity index 76%
rename from deploy/chatapp.env.example
rename to deploy/ds-chat.env.example
index 01952c8..ac90a1c 100644
--- a/deploy/chatapp.env.example
+++ b/deploy/ds-chat.env.example
@@ -1,15 +1,15 @@
-# /etc/chatapp/env  (production)
+# /etc/ds-chat/env  (production)
 #
 # This file is loaded by systemd's EnvironmentFile= (see
-# deploy/systemd/chatapp.service) directly into the app process's
+# deploy/systemd/ds-chat.service) directly into the app process's
 # environment -- it is NOT a dotenv file Python reads from a working
 # directory, and it must never be committed to the repository.
 #
 # Install:
-#   sudo mkdir -p /etc/chatapp
-#   sudo cp deploy/chatapp.env.example /etc/chatapp/env
-#   sudo chown root:chatapp /etc/chatapp/env
-#   sudo chmod 0640 /etc/chatapp/env
+#   sudo mkdir -p /etc/ds-chat
+#   sudo cp deploy/ds-chat.env.example /etc/ds-chat/env
+#   sudo chown root:ds-chat /etc/ds-chat/env
+#   sudo chmod 0640 /etc/ds-chat/env
 #   # then edit in the real values below
 #
 # See ../DEPLOYMENT.md for how each value is generated.
@@ -17,7 +17,7 @@
 # Points at the data server's PRIVATE address -- never the public one.
 # The role/password here are whatever you created on the data server in
 # DEPLOYMENT.md step 2.
-DATABASE_URL=postgresql+asyncpg://chatapp:REPLACE_ME@<DATA_SERVER_PRIVATE_IP>:5432/chatapp
+DATABASE_URL=postgresql+asyncpg://ds_chat:REPLACE_ME@<DATA_SERVER_PRIVATE_IP>:5432/ds_chat
 
 # Generate with: python3 -c "import secrets; print(secrets.token_urlsafe(32))"
 SESSION_SECRET=REPLACE_ME
diff --git a/deploy/systemd/chatapp.service b/deploy/systemd/ds-chat.service
similarity index 81%
rename from deploy/systemd/chatapp.service
rename to deploy/systemd/ds-chat.service
index 6ff30b4..d627c93 100644
--- a/deploy/systemd/chatapp.service
+++ b/deploy/systemd/ds-chat.service
@@ -1,8 +1,8 @@
-# /etc/systemd/system/chatapp.service
+# /etc/systemd/system/ds-chat.service
 #
-# Install: sudo cp deploy/systemd/chatapp.service /etc/systemd/system/
+# Install: sudo cp deploy/systemd/ds-chat.service /etc/systemd/system/
 #          sudo systemctl daemon-reload
-#          sudo systemctl enable --now chatapp
+#          sudo systemctl enable --now ds-chat
 #
 # See ../../DEPLOYMENT.md for the full app-server setup this fits into.
 # TLS termination and public-facing reverse proxying are handled by an
@@ -10,17 +10,17 @@
 # unit just needs to be reachable on the TCP port below.
 
 [Unit]
-Description=KeepItTalking chat service app server
+Description=DS Chat app server
 After=network.target
 
 [Service]
 # No Type= override -- defaults to "simple", which is correct here since
 # gunicorn runs in the foreground (no --daemon flag below) and doesn't send
 # systemd's sd_notify readiness protocol.
-User=chatapp
-Group=chatapp
-WorkingDirectory=/srv/chatapp/backend
-EnvironmentFile=/etc/chatapp/env
+User=ds-chat
+Group=ds-chat
+WorkingDirectory=/srv/ds-chat/backend
+EnvironmentFile=/etc/ds-chat/env
 Environment=PYTHONUNBUFFERED=1
 
 # 0.0.0.0 because Nginx Proxy Manager runs on a separate host -- the actual
@@ -28,7 +28,7 @@ Environment=PYTHONUNBUFFERED=1
 # port to NPM's IP specifically, not the bind address. If NPM reaches this
 # box over a private network interface, bind to that private IP instead
 # for defense in depth (belt-and-suspenders on top of the firewall rule).
-ExecStart=/srv/chatapp/backend/.venv/bin/gunicorn app.main:app \
+ExecStart=/srv/ds-chat/backend/.venv/bin/gunicorn app.main:app \
   -k uvicorn.workers.UvicornWorker \
   --workers 4 \
   --bind 0.0.0.0:8000 \
diff --git a/deploy/upgrade.sh b/deploy/upgrade.sh
index 682e6f7..ff6b9b5 100755
--- a/deploy/upgrade.sh
+++ b/deploy/upgrade.sh
@@ -1,20 +1,20 @@
 #!/usr/bin/env bash
-# Day-2 deploy/upgrade script for the KeepItTalking app server. Run by hand
-# over SSH as the `chatapp` user (or via sudo -u chatapp):
+# Day-2 deploy/upgrade script for the DS Chat app server. Run by hand
+# over SSH as the `ds-chat` user (or via sudo -u ds-chat):
 #
-#   sudo -u chatapp /srv/chatapp/deploy/upgrade.sh
+#   sudo -u ds-chat /srv/ds-chat/deploy/upgrade.sh
 #
 # Fails loudly and stops before touching the running service if any step
 # fails -- the previous deploy keeps running rather than being torn down
 # mid-upgrade. See ../DEPLOYMENT.md for what each step assumes is already
-# in place (venv, /etc/chatapp/env, the systemd unit, Node.js).
+# in place (venv, /etc/ds-chat/env, the systemd unit, Node.js).
 
 set -euo pipefail
 
-REPO_DIR="/srv/chatapp"
+REPO_DIR="/srv/ds-chat"
 BACKEND_DIR="${REPO_DIR}/backend"
 FRONTEND_DIR="${REPO_DIR}/frontend"
-ENV_FILE="/etc/chatapp/env"
+ENV_FILE="/etc/ds-chat/env"
 
 echo "==> Pulling latest code"
 cd "$REPO_DIR"
@@ -28,7 +28,7 @@ echo "==> Running database migrations"
 # alembic reads DATABASE_URL from the environment (backend/alembic/env.py),
 # so the env file has to actually be sourced into this shell first -- it's
 # not read automatically just because systemd's EnvironmentFile= points at
-# it (that only applies to the chatapp.service process, not this script).
+# it (that only applies to the ds-chat.service process, not this script).
 set -a
 # shellcheck disable=SC1090
 source "$ENV_FILE"
@@ -40,20 +40,20 @@ cd "$FRONTEND_DIR"
 npm ci --silent
 npm run build --silent
 
-echo "==> Restarting chatapp"
+echo "==> Restarting ds-chat"
 # Active WebSocket connections drop here and reconnect automatically within
 # a few seconds (frontend/src/ws/useChatSocket.ts's exponential-backoff
 # reconnect) -- expected, not a bug, and not worth a blue-green setup for.
-sudo systemctl restart chatapp
+sudo systemctl restart ds-chat
 
 echo "==> Verifying"
 sleep 2
 if curl -sf http://127.0.0.1:8000/api/health >/dev/null; then
   echo "Health check OK"
 else
-  echo "Health check FAILED -- check: sudo journalctl -u chatapp -n 50" >&2
+  echo "Health check FAILED -- check: sudo journalctl -u ds-chat -n 50" >&2
   exit 1
 fi
-sudo systemctl status chatapp --no-pager -l | head -10
+sudo systemctl status ds-chat --no-pager -l | head -10
 
-echo "==> Done. journalctl -u chatapp -f to watch logs."
+echo "==> Done. journalctl -u ds-chat -f to watch logs."
diff --git a/frontend/README.md b/frontend/README.md
index 705d4d5..390e1ee 100644
--- a/frontend/README.md
+++ b/frontend/README.md
@@ -1,4 +1,4 @@
-# KeepItTalking frontend (Phase 1)
+# DS Chat frontend (Phase 1)
 
 React + Vite PWA. Login, room list, and chat views wired to the backend's
 REST API and `/ws/chat` WebSocket endpoint. See [`../README.md`](../README.md)
diff --git a/frontend/index.html b/frontend/index.html
index 716e607..e5e5e38 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -4,7 +4,7 @@
     <meta charset="UTF-8" />
     <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <title>KeepItTalking</title>
+    <title>DS Chat</title>
   </head>
   <body>
     <div id="root"></div>
diff --git a/frontend/src/components/TopBar.tsx b/frontend/src/components/TopBar.tsx
index 68e7b66..f88650d 100644
--- a/frontend/src/components/TopBar.tsx
+++ b/frontend/src/components/TopBar.tsx
@@ -46,7 +46,7 @@ export function TopBar() {
     <header className="top-bar">
       <div className="top-bar-brand">
         <img src={logo} alt="" className="top-bar-logo" />
-        <span className="top-bar-title">KeepItTalking</span>
+        <span className="top-bar-title">DS Chat</span>
       </div>
 
       <div className="top-bar-user">
diff --git a/frontend/src/pages/ForgotPasswordPage.tsx b/frontend/src/pages/ForgotPasswordPage.tsx
index b069de0..3372a0d 100644
--- a/frontend/src/pages/ForgotPasswordPage.tsx
+++ b/frontend/src/pages/ForgotPasswordPage.tsx
@@ -32,7 +32,7 @@ export function ForgotPasswordPage() {
       <div className="login-card">
         <div className="login-brand">
           <img src={logo} alt="" />
-          <span>KeepItTalking</span>
+          <span>DS Chat</span>
         </div>
 
         {sent ? (
diff --git a/frontend/src/pages/LoginPage.tsx b/frontend/src/pages/LoginPage.tsx
index 8f69d87..1a6719e 100644
--- a/frontend/src/pages/LoginPage.tsx
+++ b/frontend/src/pages/LoginPage.tsx
@@ -34,7 +34,7 @@ export function LoginPage() {
       <div className="login-card">
         <div className="login-brand">
           <img src={logo} alt="" />
-          <span>KeepItTalking</span>
+          <span>DS Chat</span>
         </div>
         <p className="login-copy">This is an invite-only site. Ask an admin for an account.</p>
         <form className="login-form" onSubmit={handleSubmit}>
diff --git a/frontend/src/pages/ResetPasswordPage.tsx b/frontend/src/pages/ResetPasswordPage.tsx
index 492e13b..9c56043 100644
--- a/frontend/src/pages/ResetPasswordPage.tsx
+++ b/frontend/src/pages/ResetPasswordPage.tsx
@@ -59,7 +59,7 @@ export function ResetPasswordPage() {
       <div className="login-card">
         <div className="login-brand">
           <img src={logo} alt="" />
-          <span>KeepItTalking</span>
+          <span>DS Chat</span>
         </div>
 
         {checking && <p className="login-copy">Checking your reset link…</p>}
diff --git a/frontend/src/pages/SignupPage.tsx b/frontend/src/pages/SignupPage.tsx
index 4b2dfc9..c517682 100644
--- a/frontend/src/pages/SignupPage.tsx
+++ b/frontend/src/pages/SignupPage.tsx
@@ -57,7 +57,7 @@ export function SignupPage() {
       <div className="login-card">
         <div className="login-brand">
           <img src={logo} alt="" />
-          <span>KeepItTalking</span>
+          <span>DS Chat</span>
         </div>
 
         {checking && <p className="login-copy">Checking your invite…</p>}
diff --git a/frontend/vite.config.ts b/frontend/vite.config.ts
index a225d5f..22c2037 100644
--- a/frontend/vite.config.ts
+++ b/frontend/vite.config.ts
@@ -23,8 +23,8 @@ export default defineConfig({
       },
       registerType: 'autoUpdate',
       manifest: {
-        name: 'KeepItTalking',
-        short_name: 'Talking',
+        name: 'DS Chat',
+        short_name: 'DS Chat',
         start_url: '/',
         display: 'standalone',
         background_color: '#07080f', // --ds-void