fix: review round 2 -- redis guards, remove dead param, extract GitHub headers

1. indexing.py: added redis_client None guard before creating
   AnonymousIndexingJob in both start_anonymous_indexing and
   get_indexing_status. Returns 503 if Redis is down instead of
   crashing with AttributeError.
2. validation.py: removed unused 'req: Request' param from
   validate_github_repo and removed unused Request import.
3. validation.py: extracted _github_headers() helper to replace
   duplicate header construction in fetch_repo_metadata and
   count_code_files.

Skipped (duplicates): create_session error handling (3rd time),
list_repos sync (3rd time), validator dedup (refactor risk in
split PR), limit_result typing, session ordering, private method
naming, redundant get_session_data call.

289 tests pass.

Author: DevanshuNEU

backend/routes/playground/indexing.py

@@ -152,6 +152,8 @@ async def start_anonymous_indexing(
 
     # Create job and start background indexing
     response_time_ms = int((time.time() - start_time) * 1000)
+    if not redis_client:
+        raise HTTPException(status_code=503, detail="Indexing service unavailable (Redis down)")
     job_manager = AnonymousIndexingJob(redis_client)
     job_id = job_manager.generate_job_id()
 
@@ -199,6 +201,8 @@ async def get_indexing_status(job_id: str, req: Request) -> dict:
             "error": "invalid_job_id", "message": "Invalid job ID format"
         })
 
+    if not redis_client:
+        raise HTTPException(status_code=503, detail="Indexing service unavailable (Redis down)")
     job_manager = AnonymousIndexingJob(redis_client)
     job = job_manager.get_job(job_id)
 

backend/routes/playground/validation.py

@@ -3,7 +3,7 @@
 import time
 from typing import Optional
 import httpx
-from fastapi import APIRouter, HTTPException, Request
+from fastapi import APIRouter, HTTPException
 from pydantic import BaseModel, field_validator
 
 from dependencies import cache
@@ -42,18 +42,22 @@ def parse_github_url(url: str) -> tuple[Optional[str], Optional[str], Optional[s
     return match.group("owner"), match.group("repo"), None
 
 
-async def fetch_repo_metadata(owner: str, repo: str) -> dict:
-    """Fetch repository metadata from GitHub API."""
-    url = f"{GITHUB_API_BASE}/repos/{owner}/{repo}"
+def _github_headers() -> dict:
+    """Build GitHub API request headers with optional auth token."""
     headers = {"Accept": "application/vnd.github.v3+json", "User-Agent": "OpenCodeIntel/1.0"}
-
     github_token = os.getenv("GITHUB_TOKEN")
     if github_token:
         headers["Authorization"] = f"token {github_token}"
+    return headers
+
+
+async def fetch_repo_metadata(owner: str, repo: str) -> dict:
+    """Fetch repository metadata from GitHub API."""
+    url = f"{GITHUB_API_BASE}/repos/{owner}/{repo}"
 
     async with httpx.AsyncClient(timeout=GITHUB_API_TIMEOUT) as client:
         try:
-            response = await client.get(url, headers=headers)
+            response = await client.get(url, headers=_github_headers())
             if response.status_code == 404:
                 return {"error": "not_found", "message": "Repository not found"}
             if response.status_code == 403:
@@ -73,15 +77,10 @@ async def count_code_files(
 ) -> tuple[int, Optional[str]]:
     """Count code files using GitHub tree API. Returns (file_count, error)."""
     url = f"{GITHUB_API_BASE}/repos/{owner}/{repo}/git/trees/{default_branch}?recursive=1"
-    headers = {"Accept": "application/vnd.github.v3+json", "User-Agent": "OpenCodeIntel/1.0"}
-
-    github_token = os.getenv("GITHUB_TOKEN")
-    if github_token:
-        headers["Authorization"] = f"token {github_token}"
 
     async with httpx.AsyncClient(timeout=GITHUB_API_TIMEOUT) as client:
         try:
-            response = await client.get(url, headers=headers)
+            response = await client.get(url, headers=_github_headers())
             if response.status_code == 404:
                 return 0, "Could not fetch repository tree"
             if response.status_code == 403:
@@ -115,7 +114,7 @@ async def count_code_files(
 
 
 @router.post("/validate-repo")
-async def validate_github_repo(request: ValidateRepoRequest, req: Request) -> dict:
+async def validate_github_repo(request: ValidateRepoRequest) -> dict:
     """Validate a GitHub repository URL for anonymous indexing."""
     start_time = time.time()