docs: prepare session file before first container start

Add touch telegram_session.session to setup instructions and clarify
that the session file must exist (even empty) before starting the container.

LICENSE

@@ -0,0 +1,201 @@
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README.md

@@ -33,11 +33,14 @@ The example `docker-compose.yml` uses the pre-built image from [Docker Hub](http
 
 ```bash
 mkdir -p data channels logs
+touch telegram_session.session
 cp config.example.json config.json
 # edit config.json with your Telegram values
 ```
 
-> On Linux, if the container runs as a non-root user, make sure the current user has read+write access to these folders (the example compose runs as `root`).
+> **Important:** The `telegram_session.session` file must exist (even empty) before the container starts. If the container can't find the session file, it will fail to start. Create an empty file as shown above.
+
+On Linux, if the container runs as a non-root user, make sure the current user has read+write access to these folders (the example compose runs as `root`).
 
 Then start the stack:
 
@@ -46,6 +49,25 @@ docker compose up -d
 docker compose logs -f telegram-backup
 ```
 
+> **First-time login:** After the initial `docker compose up -d`, the container will start but won't be logged in yet. You need to authenticate interactively first:
+>
+> ```bash
+> # Stop the detached container
+> docker compose down
+>
+> # Run interactively — you'll be prompted for phone number + verification code
+> # (and password if you have 2FA enabled)
+> docker compose up
+>
+> # After successful login, press Ctrl+C to stop
+> docker compose down
+>
+> # Now start detached — session is saved
+> docker compose up -d
+> ```
+>
+> The session file is written to `./telegram_session.session` on the host, so subsequent starts won't ask for verification again (unless it expires or you delete the file).
+
 This is the `docker-compose.yml`:
 
 ```yaml
@@ -58,7 +80,7 @@ services:
     restart: unless-stopped
     user: root
     volumes:
-      - ./config.json:/app/config.json:ro
+      - ./config.json:/app/config.json
       - ./telegram_session.session:/app/telegram_session.session
       - ./data:/app/data
       - ./channels:/app/channels
@@ -81,12 +103,13 @@ Set `status_port` to `8080` in `config.json` to use the health check and expose
 
 ```bash
 mkdir -p data channels logs
+touch telegram_session.session
 cp config.example.json config.json
 
 docker run -d \
   --name telegram-backup \
   --restart unless-stopped \
-  -v $(pwd)/config.json:/app/config.json:ro \
+  -v $(pwd)/config.json:/app/config.json \
   -v $(pwd)/telegram_session.session:/app/telegram_session.session \
   -v $(pwd)/data:/app/data \
   -v $(pwd)/channels:/app/channels \
@@ -96,8 +119,34 @@ docker run -d \
   hoelee/telegram-backup-downloader:latest
 ```
 
+> **Important:** The `telegram_session.session` file must exist (even empty) before the container starts. Create an empty file as shown above.
+
 Follow logs with `docker logs -f telegram-backup`.
 
+> **First-time login:** After the initial `docker run -d`, the container will start but won't be logged in yet. You need to authenticate interactively first:
+>
+> ```bash
+> # Stop and remove the detached container
+> docker stop telegram-backup && docker rm telegram-backup
+>
+> # Run interactively — you'll be prompted for phone number + verification code
+> # (and password if you have 2FA enabled)
+> docker run -it --rm \
+>   -v $(pwd)/config.json:/app/config.json \
+>   -v $(pwd)/telegram_session.session:/app/telegram_session.session \
+>   -v $(pwd)/data:/app/data \
+>   -v $(pwd)/channels:/app/channels \
+>   -v $(pwd)/logs:/app/logs \
+>   -p 8080:8080 \
+>   -e TZ=Asia/Kuala_Lumpur \
+>   hoelee/telegram-backup-downloader:latest
+>
+> # After successful login, press Ctrl+C to exit
+> # Now run detached — session is saved to ./telegram_session.session
+> ```
+>
+> The session file is written to `./telegram_session.session` on the host, so subsequent starts won't ask for verification again (unless it expires or you delete the file).
+
 ### Option C: Build from source
 
 ```bash
@@ -131,6 +180,8 @@ docker compose logs -f telegram-backup
 | `channel_last_message_id_overrides` | No | `{}` | One-time per-channel sync cursor overrides. With `updateonce: true`, sets the channel's SQLite `last_message_id` to the specified value, then automatically changes `updateonce` to `false` in `config.json`. Use numeric Telegram peer IDs that are included in `channels`. |
 | `manual_downloads` | No | `{}` | Message IDs to prioritize, keyed by channel ID. Useful to force-retry specific messages. Example: `{"-1001":[42,43,44]}`. Change is detected by config watcher — no restart needed. |
 
+`config.json` must be mounted read-write. The program writes back to it directly — for example, when `channel_last_message_id_overrides` runs with `updateonce: true`, the downloader updates the database and then flips `updateonce` to `false` in the same file. A read-only mount (`:ro`) would break this and any other live config update.
+
 `config.json` is watched every 10 seconds. Changes to channels, overrides, cursor overrides, and manual downloads are applied without restarting. Do not set `status_port`, `db_path`, worker count, or API credentials expecting a live process to rebind/recreate those resources; restart after changing them.
 
 ### One-Time Sync Cursor Override

config.example.json

@@ -19,7 +19,7 @@
   "db_path": "/app/data/telegram_state.db",
   "channel_overrides": {
     "-1001231231231":{"turnon":false},
-    "-1003213213213":{"turnon":true}
+    "-1003213213213":{"turnon":false}
   },
   "channel_last_message_id_overrides": {
     "-1001231231231": {
@@ -27,7 +27,7 @@
       "last_message_id": 123123
     },
     "-1003213213213": {
-      "updateonce": true,
+      "updateonce": false,
       "last_message_id": 321321
     }
   },

docker-compose.yml

@@ -7,7 +7,8 @@ services:
     restart: unless-stopped
     user: root
     volumes:
-      - ./config.json:/app/config.json:ro
+      # config.json must be read-write — the program writes back to it (e.g. flips updateonce to false)
+      - ./config.json:/app/config.json
       - ./telegram_session.session:/app/telegram_session.session
       - ./channels:/app/channels
       - ./logs:/app/logs