fix(llm-detector): Add better platform parsing (#104475)

some platforms aren't accepted as event platform so we were seeing
`other` for `python-flask` projects for example. now, we will pass along
the best match rather than `other`
fixes
https://linear.app/getsentry/issue/ID-1130/some-issues-still-have-other-as-platform

Author: roggenkemper

.github/CODEOWNERS

@@ -578,7 +578,7 @@ pnpm-lock.yaml                                           @getsentry/owners-js-de
 /src/sentry/tasks/merge.py                                  @getsentry/issue-detection-backend
 /src/sentry/tasks/unmerge.py                                @getsentry/issue-detection-backend
 /src/sentry/tasks/weekly_escalating_forecast.py             @getsentry/issue-detection-backend
-/src/sentry/tasks/llm_issue_detection.py                    @getsentry/issue-detection-backend
+/src/sentry/tasks/llm_issue_detection/                      @getsentry/issue-detection-backend
 /static/app/components/events/contexts/                     @getsentry/issue-workflow
 /static/app/components/events/eventTags/                    @getsentry/issue-workflow
 /static/app/components/events/highlights/                   @getsentry/issue-workflow

src/sentry/tasks/llm_issue_detection/detection.py

@@ -10,6 +10,7 @@
 from pydantic import BaseModel
 
 from sentry import features, options
+from sentry.constants import VALID_PLATFORMS
 from sentry.issues.grouptype import LLMDetectedExperimentalGroupType
 from sentry.issues.issue_occurrence import IssueEvidence, IssueOccurrence
 from sentry.issues.producer import PayloadType, produce_occurrence_to_kafka
@@ -72,6 +73,30 @@ def __init__(
         self.error_message = error_message
 
 
+def get_base_platform(platform: str | None) -> str | None:
+    """
+    Extract the base platform from a platform identifier.
+
+    Examples:
+        python-flask -> python
+        python-django -> python
+        javascript-react -> javascript
+        python -> python
+    """
+    if not platform:
+        return None
+
+    if platform in VALID_PLATFORMS:
+        return platform
+
+    base_platform = platform.split("-")[0]
+
+    if base_platform in VALID_PLATFORMS:
+        return base_platform
+
+    return None
+
+
 def create_issue_occurrence_from_detection(
     detected_issue: DetectedIssue,
     trace: EvidenceTraceData,
@@ -119,10 +144,12 @@ def create_issue_occurrence_from_detection(
         level="warning",
     )
 
+    platform = get_base_platform(project.platform) or "other"
+
     event_data = {
         "event_id": event_id,
         "project_id": project_id,
-        "platform": project.platform or "other",
+        "platform": platform,
         "received": detection_time.isoformat(),
         "timestamp": detection_time.isoformat(),
         "transaction": transaction_name,