feat(config): auto-truncate commit messages over 200 chars

The --commit-message flag passes its value directly into the API request URL
as a query parameter with no length limit. AI-generated commit messages and
the common CI pattern of concatenating $BUILDKITE_BUILD_NUMBER + $BUILDKITE_MESSAGE
can easily exceed URL length limits, producing HTTP 413 errors.

The 413 originates from an infrastructure-layer URL length limit (nginx/Cloudflare),
not application-level validation -- confirmed via inspection of the Socket API route
handler, which has no constraint on commit_message (unlike committers, which enforces
<= 200 chars and returns a clean 400).

200 chars chosen as a conservative defensive ceiling given URL encoding can 2-3x
raw character count. No customer should ever want a 2000-character commit message
in their scan metadata.

A backend-side validation (returning 400 instead of 413) is filed as a follow-on
for the depscan API team.

Motivated by customer incidents (Plaid).

Signed-off-by: lelia <2418071+lelia@users.noreply.github.com>

Author: lelia

socketsecurity/config.py

@@ -177,6 +177,19 @@ def from_args(cls, args_list: Optional[List[str]] = None) -> 'CliConfig':
         if commit_message and commit_message.startswith('"') and commit_message.endswith('"'):
             commit_message = commit_message[1:-1]
 
+        # Truncate to avoid 413s from oversized URL query parameters.
+        # The API has no application-layer length validation on commit_message;
+        # the 413 originates from an infrastructure-layer URL length limit
+        # (nginx/Cloudflare). 200 chars chosen as a conservative ceiling given
+        # URL encoding can 2-3x raw character count.
+        MAX_COMMIT_MESSAGE_LENGTH = 200
+        if commit_message and len(commit_message) > MAX_COMMIT_MESSAGE_LENGTH:
+            logging.debug(
+                f"commit_message truncated from {len(commit_message)} to "
+                f"{MAX_COMMIT_MESSAGE_LENGTH} characters to avoid API request size limits"
+            )
+            commit_message = commit_message[:MAX_COMMIT_MESSAGE_LENGTH]
+
         config_args = {
             'api_token': api_token,
             'repo': args.repo,