diff --git a/README.md b/README.md
index b159508..82a08e3 100644
--- a/README.md
+++ b/README.md
@@ -61,6 +61,7 @@ syncgames doctor
 | [docs/protocol.md](docs/protocol.md) | Shared SSOT protocol (Python ↔ Android) |
 | [docs/nas-minio-cloudflare.md](docs/nas-minio-cloudflare.md) | MinIO + NGINX + Cloudflare |
 | [docs/add-game.md](docs/add-game.md) | Add / remove games |
+| [docs/seamless-save-paths.md](docs/seamless-save-paths.md) | Seamless Coop `.co2` locations (per-device) |
 | [docs/fallback-path1.md](docs/fallback-path1.md) | Syncthing fallback |
 | [docs/planning/](docs/planning/) | Planning archive |
 
diff --git a/agent/syncgames/watchers.py b/agent/syncgames/watchers.py
index 073a4b5..826e908 100644
--- a/agent/syncgames/watchers.py
+++ b/agent/syncgames/watchers.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import time
+from pathlib import Path
 from typing import Callable
 
 from syncgames.config import GameConfig
@@ -26,18 +27,21 @@ def is_game_running(game: GameConfig) -> bool:
             pname = _norm(proc.info["name"] or "")
             if names and pname in names:
                 return True
-            if names and any(pname == _norm(n) for n in names):
-                return True
             cmd = proc.info.get("cmdline") or []
-            joined = " ".join(cmd).lower()
-            if appid and (
-                f"appid={appid}" in joined
-                or f"steam_appid={appid}" in joined
-                or f"AppId={appid}" in joined
-            ):
-                return True
-            for n in game.process_names:
-                if n.lower() in joined:
+            # Match executable basenames only — never substring-search the full
+            # cmdline (e.g. `syncgames end eden-saves` must not look like Eden).
+            for part in cmd[:2]:
+                if not part:
+                    continue
+                if _norm(Path(part).name) in names:
+                    return True
+            if appid:
+                joined = " ".join(cmd).lower()
+                if (
+                    f"appid={appid}" in joined
+                    or f"steam_appid={appid}" in joined
+                    or f"appid={appid}" in joined
+                ):
                     return True
         except (psutil.Error, TypeError):
             continue
diff --git a/config/agent.toml.example b/config/agent.toml.example
index 29999e6..36bb3d7 100644
--- a/config/agent.toml.example
+++ b/config/agent.toml.example
@@ -1,6 +1,7 @@
 # Copy to ~/.config/syncgames/agent.toml or SyncGames/config/agent.toml
 
-device_id = "pc-desk"
+# Unique per machine (this desktop = Jorg, laptop = terra, …)
+device_id = "Jorg"
 store = "minio"  # or "filesystem" for Path 1 fallback
 
 # WAN HTTPS via Cloudflare → NGINX → MinIO (path-style)
diff --git a/config/devices.toml b/config/devices.toml
index f9779d8..1eb7ae6 100644
--- a/config/devices.toml
+++ b/config/devices.toml
@@ -1,12 +1,13 @@
 # Registry of known devices (documentation / optional tooling)
+# Each machine sets its own device_id in ~/.config/syncgames/agent.toml
 
 [[devices]]
-id = "pc-desk"
+id = "Jorg"
 os = "linux"
 role = "desktop"
 
 [[devices]]
-id = "laptop"
+id = "terra"
 os = "linux"
 role = "laptop"
 
diff --git a/config/games/dark-souls-2-sotfs.toml b/config/games/dark-souls-2-sotfs.toml
index a6480e3..e51c386 100644
--- a/config/games/dark-souls-2-sotfs.toml
+++ b/config/games/dark-souls-2-sotfs.toml
@@ -2,6 +2,9 @@ id = "dark-souls-2-sotfs"
 name = "Dark Souls II Scholar of the First Sin (Seamless Coop)"
 platform = "steam"
 versions_to_keep = 5
+# Seamless Coop uses a separate extension (.co2). Non-Steam launches use a
+# random compatdata id — verify on each device:
+#   find ~/.steam/steam/steamapps/compatdata -iname '*.co2' | grep -i DarkSoulsII
 paths = [
   "~/.steam/steam/steamapps/compatdata/335300/pfx/drive_c/users/steamuser/Application Data/DarkSoulsII",
 ]
diff --git a/config/games/dark-souls-3.toml b/config/games/dark-souls-3.toml
index 36fc6a4..e2b8538 100644
--- a/config/games/dark-souls-3.toml
+++ b/config/games/dark-souls-3.toml
@@ -2,8 +2,12 @@ id = "dark-souls-3"
 name = "Dark Souls III (Seamless Coop)"
 platform = "steam"
 versions_to_keep = 5
+# Seamless Coop save extension = .co2. Non-Steam / me3 shortcut prefix — NOT
+# vanilla 374320. Find with:
+#   find ~/.steam/steam/steamapps/compatdata -name 'DS30000.co2'
+# Note: Roaming\DarkSoulsIII (not Application Data) under Proton for this install.
 paths = [
-  "~/.steam/steam/steamapps/compatdata/374320/pfx/drive_c/users/steamuser/Application Data/DarkSoulsIII",
+  "~/.steam/steam/steamapps/compatdata/2678480877/pfx/drive_c/users/steamuser/AppData/Roaming/DarkSoulsIII/0110000103f10730",
 ]
 steam_appid = 374320
 process_names = [
diff --git a/config/games/dark-souls-remastered.toml b/config/games/dark-souls-remastered.toml
index 126b492..b5e8279 100644
--- a/config/games/dark-souls-remastered.toml
+++ b/config/games/dark-souls-remastered.toml
@@ -2,7 +2,9 @@ id = "dark-souls-remastered"
 name = "Dark Souls Remastered (Seamless Coop)"
 platform = "steam"
 versions_to_keep = 5
-# Adjust USERNAME / Steam library path on each device after install.
+# Seamless Coop .co2 lives under a non-Steam compatdata prefix when launched via
+# me3 / shortcut. Find per device:
+#   find ~/.steam/steam/steamapps/compatdata -iname '*.co2' | grep -i 'DARK SOULS\|NBGI'
 paths = [
   "~/.steam/steam/steamapps/compatdata/570940/pfx/drive_c/users/steamuser/Documents/NBGI/DARK SOULS REMASTERED",
 ]
diff --git a/config/games/elden-ring-seamless.toml b/config/games/elden-ring-seamless.toml
index a1cc72a..bf9f6d3 100644
--- a/config/games/elden-ring-seamless.toml
+++ b/config/games/elden-ring-seamless.toml
@@ -2,11 +2,14 @@ id = "elden-ring-seamless"
 name = "Elden Ring (Seamless Coop)"
 platform = "steam"
 versions_to_keep = 5
-# Seamless Coop writes alongside vanilla saves under EldenRing/<SteamID>/
-# Point at the SeamlessCoop subdirectory once present, or the parent character folder.
+# Seamless Coop uses .co2 (not vanilla .sl2). Non-Steam / me3 launches create a
+# NEW compatdata id — NOT vanilla 1245620. Find with:
+#   find ~/.steam/steam/steamapps/compatdata -name 'ER0000.co2'
+# Sync the SteamID folder that contains ER0000.co2 (per-device path).
 paths = [
-  "~/.steam/steam/steamapps/compatdata/1245620/pfx/drive_c/users/steamuser/AppData/Roaming/EldenRing",
+  "~/.steam/steam/steamapps/compatdata/3917582188/pfx/drive_c/users/steamuser/AppData/Roaming/EldenRing/76561198026393392",
 ]
+# Vanilla appid kept for reference; watcher mainly uses process names.
 steam_appid = 1245620
 process_names = [
   "eldenring.exe",
diff --git a/docs/add-game.md b/docs/add-game.md
index 0c70f22..1a60a31 100644
--- a/docs/add-game.md
+++ b/docs/add-game.md
@@ -20,6 +20,18 @@ Effects:
 
 Multiple `--paths` allowed. Globs are expanded at session time.
 
+### Seamless Coop (Souls / Elden Ring)
+
+Modded saves use **`.co2`**, not vanilla `.sl2`. Non-Steam / me3 launchers create a **new** Proton `compatdata/<id>` — not the vanilla Steam AppID folder.
+
+See **[seamless-save-paths.md](seamless-save-paths.md)** for discovery steps and known Jorg desktop paths (reference for satellites — always re-find on each device).
+
+```bash
+find ~/.steam/steam/steamapps/compatdata -name '*.co2'
+```
+
+Point `paths` at the directory that contains the `.co2` (per machine — the compatdata id can differ on `terra` vs `Jorg`). SteamID subfolders usually match across devices on the same Steam account.
+
 ### Platforms
 
 | Value | Meaning |
diff --git a/docs/seamless-save-paths.md b/docs/seamless-save-paths.md
new file mode 100644
index 0000000..396b22e
--- /dev/null
+++ b/docs/seamless-save-paths.md
@@ -0,0 +1,41 @@
+# Seamless Coop save locations
+
+Seamless Coop does **not** use the vanilla Steam save slot as the live character file. It uses a separate extension (usually **`.co2`**) so co-op progress cannot corrupt `.sl2`.
+
+When the game is launched via **me3**, a **non-Steam Steam shortcut**, or a copied Proton prefix, Steam creates a **new** `compatdata/<random_id>/` — **not** the vanilla AppID (`1245620`, `374320`, …).
+
+## Discover on any device
+
+```bash
+find ~/.steam/steam/steamapps/compatdata ~/.local/share/Steam/steamapps/compatdata \
+  -type f -name '*.co2' 2>/dev/null
+```
+
+Point SyncGames `paths` at the **directory that contains** the `.co2` (the SteamID / account subfolder). Do this **per device** — the numeric `compatdata` id often differs between `Jorg` and `terra` even for the same mod launch method. The SteamID folder name is usually stable on one Steam account.
+
+## Known locations (Jorg desktop — reference only)
+
+| Game id | Compatible discovery | Path used on Jorg |
+|---------|----------------------|-------------------|
+| `elden-ring-seamless` | `ER0000.co2` | `~/.steam/steam/steamapps/compatdata/3917582188/pfx/drive_c/users/steamuser/AppData/Roaming/EldenRing/76561198026393392` |
+| `dark-souls-3` | `DS30000.co2` | `~/.steam/steam/steamapps/compatdata/2678480877/pfx/drive_c/users/steamuser/AppData/Roaming/DarkSoulsIII/0110000103f10730` |
+| `dark-souls-2-sotfs` | *(no `.co2` on Jorg yet)* | Still template vanilla path — replace after first Seamless launch |
+| `dark-souls-remastered` | *(no `.co2` on Jorg yet)* | Still template vanilla path — replace after first Seamless launch |
+
+Older / alternate prefixes may hold conversion leftovers (e.g. `ER0000.cnv.co2` under `3182145933` on Jorg). Prefer the newest live `.co2`, not `.cnv.co2`, unless you intentionally migrate.
+
+## Satellite checklist (`terra`, …)
+
+1. Install AppImage; Setup → same MinIO keys; **`device_id = "terra"`** (or that machine’s id).
+2. Seed/add games; run the `find … '*.co2'` command above.
+3. Edit each game’s path to **this** machine’s directory (GUI Load → Save, or `syncgames edit`).
+4. **Start** → pulls SSOT into the local Seamless folder → play → **End**.
+
+Optional automation after paths are correct:
+
+```bash
+./systemd/install-user-units.sh
+# ensure syncgames is on PATH, e.g. symlink AppImage CLI or pip install -e
+systemctl --user enable --now syncgames-watch@elden-ring-seamless.service
+systemctl --user enable --now syncgames-watch@dark-souls-3.service
+```