Fix OOM crash during dashcam upload: stream multipart body instead of buffering in memory

First real-hardware test of dashcam retrieval kept crashing the whole
yaris-obd service (repeated SIGKILL/OOM on the Pi 3's ~900MB RAM) a few
minutes into every run, aborting in-flight file copies. Root cause:
_upload_dashcam_files() used requests.post(files={"file": f}), which
builds the entire multipart/form-data body in memory before sending -
fine for small payloads, but this dashcam's real clips average ~320MB
each (up to a couple hundred more with overhead), so every dashcam
upload attempt alone could push the process well past 300-600MB, and
the Pi's OOM killer stepped in immediately.

Reproduced in isolation: uploading a 300MB file the old way spiked the
client process from 28MB to 628MB RSS; switching to requests-toolbelt's
MultipartEncoder (which streams the file in chunks as the request body
is sent, instead of materializing it up front) kept it flat at ~29MB
for the same upload, with an identical byte-for-byte result on the
receiving end. No server-side changes needed - the wire format is
unchanged, still ordinary multipart/form-data.

Added requests-toolbelt to requirements.txt.

Co-authored-by: Copilot <[email protected]>

modules/app_upload.py

@@ -31,6 +31,7 @@ from threading import Thread
 
 import requests
 from dotenv import load_dotenv
+from requests_toolbelt import MultipartEncoder
 
 from modules import app_sql, app_dash, app_cellular
 
@@ -175,12 +176,26 @@ def _upload_dashcam_files():
         if app_sql.dashcam_file_marked_uploaded(rel_path, sha256):
             continue
 
+        # Stream the multipart body via MultipartEncoder instead of requests'
+        # plain files=/data= kwargs. requests builds a non-streamed files=
+        # upload by reading the *entire* file into memory up front to
+        # assemble the multipart body - fine for small files, but real
+        # dashcam clips run 300+MB each, and on a ~1GB-RAM Pi 3 that alone is
+        # enough to trigger the OOM killer (confirmed against real hardware:
+        # RSS spiked in lockstep with dashcam file size). MultipartEncoder
+        # reads the file in small chunks as the request is sent instead.
         with open(abs_path, "rb") as f:
+            encoder = MultipartEncoder(
+                fields={
+                    "relative_path": rel_path,
+                    "sha256": sha256,
+                    "file": (os.path.basename(abs_path), f, "application/octet-stream"),
+                }
+            )
             resp = requests.post(
                 f"{SERVER_URL}/api/v1/dashcam/upload",
-                data={"relative_path": rel_path, "sha256": sha256},
-                files={"file": f},
-                headers=_headers(),
+                data=encoder,
+                headers={**_headers(), "Content-Type": encoder.content_type},
                 timeout=300,
             )
         resp.raise_for_status()

requirements.txt

@@ -6,3 +6,4 @@ python-dotenv
 pyserial
 obd
 requests
+requests-toolbelt